CA1298700C - Protective box for electronic circuits hardened with respect to x-rays - Google Patents
Protective box for electronic circuits hardened with respect to x-raysInfo
- Publication number
- CA1298700C CA1298700C CA000534534A CA534534A CA1298700C CA 1298700 C CA1298700 C CA 1298700C CA 000534534 A CA000534534 A CA 000534534A CA 534534 A CA534534 A CA 534534A CA 1298700 C CA1298700 C CA 1298700C
- Authority
- CA
- Canada
- Prior art keywords
- protective box
- mechanical structure
- metal
- box according
- ray protection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F1/00—Shielding characterised by the composition of the materials
- G21F1/02—Selection of uniform shielding materials
- G21F1/10—Organic substances; Dispersions in organic carriers
- G21F1/103—Dispersions in organic carriers
- G21F1/106—Dispersions in organic carriers metallic dispersions
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/552—Protection against radiation, e.g. light or electromagnetic waves
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Abstract
ABSTRACT OF THE DISCLOSURE
Protective box for electronic circuits hardened with respect to X-rays.
The protective box comprises a base and a cover fixed to the base, formed from a rigid mechanical structure constituted by a composite material formed by a fibre-reinforced resin, an X-ray protection material partly covering the outer surface of the mechanical structure, said X-ray protection material being formed by a resin matrix containing a powder of a metal with an atomic number at least equal to 47 and with a melting point at least equal to 630°C, a material formed from an element with a low atomic number forming the outer surface of the cover and optionally a good electricity conducting material covering the inner surface of the mechanical structure.
Application to electronic circuits on-board aircraft.
Protective box for electronic circuits hardened with respect to X-rays.
The protective box comprises a base and a cover fixed to the base, formed from a rigid mechanical structure constituted by a composite material formed by a fibre-reinforced resin, an X-ray protection material partly covering the outer surface of the mechanical structure, said X-ray protection material being formed by a resin matrix containing a powder of a metal with an atomic number at least equal to 47 and with a melting point at least equal to 630°C, a material formed from an element with a low atomic number forming the outer surface of the cover and optionally a good electricity conducting material covering the inner surface of the mechanical structure.
Application to electronic circuits on-board aircraft.
Description
~ lZ~87()0 PROTECTIVE BOX FOR ELECTRONIC CIRCUITS HARDENED WITH
RESPECT TO X-RAYS
BACKGROUND OF THE INVENTION
The present invention relates to a protective box for electronic circuits hardened with respect to X-rays. It more especially applies to protecting high performance electronic circuits used in the aeronautical and space fields against X-rays.
High-performance electronic circ~its, both from the processing speed and the capacity standpoints, are very sensitive to the effects of X-rays. These effects can even lead to the destruction of the active components of the electronic circuits involving latch up phenomena.
Apart from the X-radiation dose or quantity received, a particularly important parameter isthat of the time during which said quantity is supplied. The dose associated with its application time is called the dose rate. The behaviour or resistance of the active components of the electronic circuits with respect to said parameters (dose, dose rate) and the energy spectrum of said radiation is essentially linked with the production technology thereof. In most cases, it is necessary to reduce the dose levels and rates in order to permit the electronic circuits to retain their functional integrity.
One of the most widely used methods for reducing doses and dose rates received by electronic circuits consists of SP 3005.69 LC
- lzss7ao enclosing them in an envelope made from a pure metal with a high atomic number. The metal and thickness of the metal sheet are chosen and adapted as a function of the energy of the X-radiation in question and the desired filtering rate.
This metal sheet effectively protects against high X-ray doses and dose rates. As a function of the circuits and/or technology of the electronic components, the need for protection can be felt as from 1 to 10 Krad and 105 to 107 rad.s.
Generally, the metal sheet covers a metal structure, particularly of light alloy, enclosing the electronic circuits, said structure providing the necessary mechanical strength and protection. The metal sheet is mechanically fixed over the entire outer surface of the metal structure.
Unortunately the realization of the most interesting metals for this type of protection is difficult and costly. Moreover, the requirements with respect to said protection materials and the guarantee that they will not deteriorate under various ionizing, mechanical and climatic surrounding conditions means that the weight breakdown of the electronic circuits is highly increased, compared with circuits which are not protected against X-rays.
In most cases, the metal sheet for protecting against X-rays cannot be engaged directly over the entire outer surfaces of the metal structure of the encapsulating box due to the SP 3005.69 LC
lZ98700 often complex profile thereof. This profile complexity is often imposed by heat dissipation constraints.
Therefore the volume defined by the metal protection sheet is greater than the volume of the mechanical structure to be protected. This leads to an increase in the weight and overall dimensions of the mechanical structure, which is further increased by the mechanical devices required for maintaining the metal sheet in place on the mechanical structure (spacers, angle brackets, screws, bolts, etc.).
In addition, these maintenance devices must be made from the same metal as the metal protection sheet, so as not to create "holes" in the protection against X-rays.
Furthermore, as the mechanical structure is made from a metal or alloy, this further increases the total weight of the box for encapsulating the electronic circuits.
It is clear that these disadvantages as regards the overall dimensions and weight of encapsulating boxes are particularly prejudicial with respect to the use of electronic circuits on-board aircraft.
Another method consists of directly depositing the X-ray protection metal on the mechanical structure to be protected either by impregnating the latter in a liquid bath, or by electrolysis. However, these deposition processes are not possible for all the metals usable for providing protection SP 3005.69 LC
.. ..... ... .. . . . . . . .
- ~Z9~700 against X-rays. Moreover, in this case it is al~o necessary to examine the corrosion compatibilities of the metals present.
In addition, the thicknesseg which can be deposited for the metals lending themselves to this procedure are limited, otherwise the deposit adhesion quality may be prejudiced.
Moreover, the obtaining of a homogeneous deposit makes it necessary to proceed in successive stages with further machining bet~een the deposits so that, in certain cases, the dimensions of the encapsulating box are respected in the final stage. Thus, these deposition methods are limited and lead to a high cost of the X-ray protection encapsulating boxes.
Another approach consists of envisaging a specific protection for each on-board electronic component, ~-hich constitutes a different and more advance solution compared with those referred to hereinbefore This specif~c protection described in FR-A-2 547 113, published on December 7,1984, consists of using several stacked layers of different materials having different atomic number~ (Z).
Materials with a high atomic number are dielectric ceramics, such as barium or neodymium titanate, titanium oxide or a complex lead-based ceramic. Materials having a low atomic number are carbon, aluminium, silicon, alumina and silica.
sP 3005 . 69 LC
1298';'~0 As n function of the applications and number Or componentQ
involved, the number of individual protections can be more disadvantageous from the weight standpoint than an overall protection of all the electronic components. Moreover, the technology for producing the different materials forming the piles or stacks is based on processes used for the production of capacitors and in particular fritting processes. In particular, the process described does not make it possible to obtain an X-ray protection material with a complex shape.
Within the framework of protecting persons working in the presence of X-rays, the materials mainly comprise a charge ~uch as lead, dispersed in an organic binder. Such protection materials are in particular described in FR-A-2 482 761, published on November 20, 1981 and Us-A-3 622 432 of H.K. Porter Company.
These lead-based materials can only be used as X-ray protection materials for radiation with a low flow rate a~sociated with relatively long dose distribution times.
( Another known electronic circuit encapsulating box is described in FR-A-2 490 917,` published on M~ch 26,1982. This box is made from a moulded plastic material, such as an epoxy resin, in which the electronic circuits are embedded.
This box is extremely thin and does not make it possible to effectively mechanically protect the electronic circuits.
SP 3005.69 LC
~4 lZ987~0 Moreover, there is no X-ray protection.
The present invention relates to a box for protecting electronic circuits hardened with respect to X-rays and making it possible to obviate the various disadvantages referred to hereinbefore. Compared with the use of a heavy metal sheet covering a metal structure, this protective box in particular leads to an important weight and overall dimension gain, whilst effectively protecting against radiation with a high dose rate and in particular exceeding those referred to hereinbefore.
MOreover, this protective box causes no major manufacturin~
problem and can be manufactured in a much shorter time than th~t necessary for manufacturing prior art encapsulating boxes.
Moreover, compared with FR-A-2 547 113, published on December 7, 15 1984, the invention makes it possible to bring about a development of the X-ray protection levels without any detrimental affect on the definition of the electronic circuits contained in the box.
SUMMARY OF THE INVENTION
The present invention specifically relates to a protective box for electronic circuits hardened with respect to X-rays, wherein it comprises at least one element formed from a rigid mechanical structure made from a composite material, constituted by a fibre-reinforced resin, and an X-ray SP 3005.69 LC
lZ98700 protection material at least partly covering the mechanical structure and which is formed from a resin matrix containing, in the form of a regularlydispersed powder, at least one metal and/or at least one inorganic compound of a metal, the powder only melting at a temperature at least equal to 630C and the metal having a high atomic number at least equal to 47.
In particular, the powder can be constituted by a metal and an inorganic compound of said same metal or another metal. This metal and this inorganic compound has a melting temperature equal to or above 630C.
The term element of the box is understood to mean any part used in the formation of the box, such as the cover or the base on which the cover is fixed, as well as part of the cover or base (case of a cover or base in several parts).
The X-ray protection must be associated with all the vi~ible faces of the box, bearing in mind the random directlon of X-rays.
The use of materials with high melting points makes it possible to avoid undesirable effects due to heat shocks caused within the material during X-radiation, such as the surface melting of the powder grains which can lead to the destruction of the protective material. Moreover, the use of a metal with a high atomic number equal to or greater than 47 permits an effective X-ray filtering.
SP 3005.69 LC
lZ9~71:?0 For an equal material quantity, the use of powder regularly distributed in a resin matrix leads to an efficiency loss compared with pure sheet metal, all other conditions being the same. As this efficiency loss is essentially a function of the grain size of the powder and the powder quantity in the organic binder, preference is given to a powder having a grain size between 0.5 and 25 ~m and e.g. between 1.6 and 10 ~um.
In the same way the powder quantity in the binder can range between 25 and 50% by volume of the finished X-ray protection material. The doping quantity of the organic binder in this range is a function of the sought X-ray protection efficiency.
This also applies with respect to the thickness of the X-ray protection material.
The resin used for forming the matrix of protective material can be a thermoplastic or thermosetting resin, whose heat expansion coefficient is compatible with that of the composite material forming the mechanical structure and whose polymerization catalyst is compatible with the resin of said composite material.
As a resin entering into the composition of the X-ray protection material, examples are polyamides, polyethers, polyesters, phenoplastics, polyolefines, epoxydes, polyimides, silicones, furans, etc.
The metal powder embedded in the organic matrix of the SP 3005.69 LC
129137~)0 _ 9 _ X-ray protection material can be a silver, antimony, barium, rare earth, tantalum, tungsten, rhenium, iridium, platinum, gold, uranium or hafnium powder or a powder formed from a mixture of these metals. Preference is given to the use of silver, tantalum, tungsten or uranium.
When the powder is formed by an inorganic component, the latter can be an oxide, a nitride or a carbide of a heavy metal, such as those referred to hereinbefore. In particular, the inorganic compound is an oxide, nitride or carbide of silver, tantalum, tungsten or uranium when said compound effectively exists.
In order to optimize the protection against X-rays over a very broad energy spectrum, it is possible to use one or more metals and/or one or more inorganic compounds of a metal.
The rigid mechanical structure is constituted by a material able to withstand the mechanical stresses which the final protective box is exposed. It can be formed from a thermoplastic or thermosetting resin reinforced by fibres.
However, in order to ensure an excellent mechanical strength, preference is given to the use of thermosetting resins, such as epoxy, phenolic, polyester, polyimide and furan resins.
The reinforcing fibres can he short or long and can be made from an organic or inorganic material, such as glass, carbon, boron, kevlar or metal.
SP 3005.69 LC
. . .
izg~700 _ 10 --This composite materinl (resin + fibres) has a den~ity between 1.2 and 1.8 instead Or 2.8 for aluminium. The weight gain of a rigid structure according to the invention i~
consequently significant.
The mechanical structure has a shape and size corresponding to the needs for fixing and housing the electronic circuits to be located there. It is obtained by moulding by injection, by compression or by a hybrid method called "compression-transfeF mouldin~". de~cribed in French patent application 0 2591525 published on March 23,1988.
On the thus obtained rigid structure is effected a potting of the X-ray protection material either by injection, or by compression. In order to ensure a good adhesion of the X-ray protection material to the mechanical structure, the latter can be pre~iously heated and/or can be subject to a surface preparation.
In order to obtain a good distribution of the powder in the organic binder forming the X-ray protection material for bringing about homogeneity of the opacity, prior to potting premixing takes place of the powder and binder. Thi~
premixing is performed either by mixing the po~-der with melted grains of resin and then forming mixture granules by extrusion, or by simply mixing the powders, or by mixing the powder in an organic liquid binder. This premix is then introduced in the mould to be polymerized on the - mechanical structure.
~, SP 3005.69 LC
lZg87~0 The production of the X-ray protection material by potting makes it possible to ensure a continuous, homogeneous adhesion of the material on the rigid mechanical structure.
This makes it possible to reduce the overall dimensions of the encapsulating box compared with the prior art solutions.
In order to improve the attachment of the X-ray protection material to the rigid mechanical structure, the latter can have slots formed during the moulding of the structure.
These slots are filled with X-ray protection material during the potting thereof, thus ensuring a sought supplementary attachment effect.
In order to prevent the emission of electrons by the walls or elements of the protection box during X-ray irradiation and in particular by the metal powder, the box element can be covered with a material formed from at least one element having a low atomic number, at the most equal to 6, at least partly constituting the outer or inner surface of said box element.
This material has a thickness exceeding the mean free travel of the electrons emitted by the walls of the box protected against X-rays during X-ray irradiation. It always forms the final layer with respect to the surrounding atmosphere.
The element with a low atomic number can be carbon, boron or beryllium.
SP ~005.69 LC
lZ987~0 The material for preventing the emissivity effects of the protective box walls iB generally known under the name anti-SGEMP material (System Generaling ElectroMagnetic Pulse). It can be in the form of a paint containing particles of the element with an atomic number at the most equal to 6 and is e.g. of Astral type Pyrofle~ 7D 713.
Advantageously, the considered element of the protective box is e~uipped with a material which is a good electricity conductor which serves to filter the electromagnetic waves other than the X-rays, whereby said material covers the outer surface of the assembly formed by the mechanical structure and the X-ray protection material and/or the inner surface of said mechanical structure. This good electricity conducting material constitutes a Faraday cage protecting the electronic circuits located in the protective box and will hereinafter be called a faradization material. The faradization material can be nickel, silver, pure aluminium, copper and beryllium. Beryllium has the advantage of being able to serve both as an anti-SGEMP material and as a Faraday cage, due to its low atomic number and its good electrical conductivity.
BRIEF DESCRIPTION OF THE DRAWTNGS
The invention is described in greater detail hereinafter relative to non-limitative embodiments and the attached drawings, wherein show:
Fig. 1 Diagrammatically in longitudinal section a first embodiment Or the protection means according to ~' SP 3005.69 LC
lZ98~ 0 the invention.
Fig. 2 Diagrammatically and in longitudinal section a second embodiment of the protection means according to the invention.
Fig. 3 Diagrammatically and in longitudinal section a third embodiment of the protection means according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
With a view to simplifying the description, the latter refers to a protective box formed from a monoblock cover fixed to base and formed by a single part, in which the element liable to be irradiated by X-rays is the box. The possible directions of the X-ray flux are represented by arrows F in figs. 1 to 3. As stated hereinbefore, the invention clearly has a much wider application.
Fig. 1 diagrammatically shows in longitudinal section a box for protecting electronic circuits having a base 2, on which is fixed a cover 4, e.g. using screws 6. This box receives electronic circuits 8. In particular, these circuits can be fixed by any known means to bosses 10 provided for this purpose on the inner face of the box cover 4. In very diagrammatic manner as it does not form part of the object of the invention, the electronic circuits 8 are connected to electrical circuits outside the box by conductive tracks indicated at 12 and which e.g. pass through the box space 2.
SP 3005.69 LC
129137(~0 The qpecific ~hape of the box, aq well as the fixing and connection of the electronic circuits located in the X-ray protection box are linked with the type of components uced.
These components can be encapsulated in boxes T0 5, T0 66, etc.
According to the invention, cover 4 has a rigid structure 14 ensuring the mechanical protection of the electronic circuits.
Structure 14 is formed from a thermosetting plastics material, such as bakelite, polyimide resin or silicones, reinforced by organic or non-organic fibres. Structure 14 is e.g.
made from KINEL 5504 marketed by Rhône Poulenc, said material being a polyimide resin reinforced by long glass fibres arranged in a random manner. This rigid structure 14 is formed by moulding, either by injection, or by compression, said procedures being well known to the Expert. It can have a thickness of 2 mm.
The protection against X-rays of the electronic circuits 8 located in the box is ensured with the aid of a layer material 16 in contact with the inner surface of the rigid structure 14 or, as ~hown in the drawing, in contact with the outer surface of the rigid structure.
The X-ray protection material 16 covers all the outer surface of structure 14 liable to be irradiated by X-rays.
In the case shown in fig. 1, the material layer 16 covers the entire outer surface of structure 14, namely upper face SP 3005.69 LC
lZ9~
15 and side faces 17 of sAid structure.
In order to ensure a good adhesion of the protective material 16 to rigid structure 14, the latter can have slots 18 formed during the moulding of the rigid structure 1~. These slots 18 are filled with X-ray protection material during the potting of the latter.
The X-ray protection material 16 is e.g. formed from a tungsten powder representing 30% by volume of the finished product and which is regularly dispersed in a PAll resin produced by ATOCHFM. This resin is a thermoplastic polyamide resin. The tungsten powder has an average grain size of 4 ~m, a dispersion of 2.5 and a purity of 99.9%.
This protective material can be obtained by melting granules of PAll resin, to which the tungsten powder is added. The premix obtained is introduced into a Werner~ ZSK30 extruder-granulator, in order to obtain mixture granules which can then be introduced into a mould already containing the ( rigid structure 14 to be covered by the X-ray protection material. The introduction of the mixture granules into the mould takes place by injection. The potting of the X-ray protection material is assured on rigid structure 14 heated in order to facilitate the adhesion of the X-ray material. The protective material obtained can have a thickness of 1.5 mm.
.7 ,~
~, SP 3005.69 LC
lZ98~7C~0 - 16 _ The moulding and potting respectively of rigid structure 14 and X-ray protection material 16 make it possible to directly obtain protective box covers with the requisite dimensions and accuracies without further machining being required. Moreover, these moulding procedures are particularly advantageous from the financial and manufacturing time standpoints, because the runs of box covers to be produced make it possible to reduce the costs of specific tools for each box model.
The X-ray protection material can also be constituted by a powder containing 6% by volume of tungsten and 240~ by volume of uranium dioxide (U02) embedded in P~ll resin.
This material can have a thickness of 2 mm, in order to ensure effective filtering.
In the same way, the PAll polyamide resin can be replaced by a polyether block amide resin, such as that marketed under the trade name DINYL by Rhône-Poulenc. The resin of protective material 16 can also be bakelite or silicone.
To avoid raising the electromagnetic level due to electron emission by the outer walls of the protective box during X-ray irradiation and in particular by the metal contained in the X-ray protection material 16, an anti-SGEMP material 20 forming the outer surface of cover 4 can be provided.
In the case shown in fig. 1, material 20 covers the entire X-ray protection material 16. It is made from beryllium so SP 3005.69 LC
lZ98700 that, apart from the anti-SGEMP function, itprovides the necessary protection of electronic circuits 8 against electromagnetic waves.
The closing of the Faraday cage is obtained for the case described here by the presence of base 2 made or covered by a good electricity conducting metal, such as nickel, silver, aluminium, beryllium or copper. Material 20 must have a thickness exceeding the free mean travel of the electrons emitted by the walls of the cover and also constitutes a covering for the final layer. In particular, in the case of an X-ray protection material covering the inner surface of the mechanical structure, the anti-SGEMP material advantage-ously constitutes the internal surface of the cover. It is possible to envisage the simultaneous use of an anti-SGEMP
layer constituting the inner surface of the box and an anti-SGEMP layer constituting the outer surface of the box.
Fig. 2 shows a second embodiment of the protective means according to the invention, in which the material used for preventing the emissivity effects of the walls of the case exposed to X-rays and in particular material 16 is made from a poor electricity conductor, such as carbon or boron.
Under these conditions, the protection of integrated circuits 8 against electromagnetic waves is not assured.
In order to assure this protection, the inner surface of the rigid structure 14 is completely covered with a good SP 3005.69 LC
electricity conducting layer 22. In particular layer 22 is made from a metal, such as nickel or silver. Layer 22 has a thickness of approximately 0.1 mm. The other parts of the protective box and in particular cover 4 are unchanged compared with fig. 1.
Fig. 3 shows a third embodiment of the protective box according to the invention. This embodiment differs from that of fig. 2 only in that the layer serving as the Faraday cage is positioned between the anti-SGEMP material layer 20a and the X-ray protection material layer 16. Layer 24 has a thickness of 0.1 mm and is`in particular made from silver or nickel.
As in the case of fig. 1, the Faraday cage is closed by the presence of base 2 made from a metal or covered with-a metal which is a good electricity conductor.
In order to simplify the manufacture of the protective boxaccording to the invention and ensure a good insulation of the electronic circuits 8 against electromagnetic waves, it is possible to provide a faradization layer 22-24 covering both the inner face of mechanical structure 14 (fig. 2) and the outer surface of the X-ray protection material 16 (fig. 3). This can be carried out by simply immersing the mechanical structure 14 coated with protective material 16 in a bath containing the metals to be deposited to serve as a Faraday cage (chemical deposition).
SP 3005.69 LC
It should be noted that the metal faradization layer cannot be applied to a silicone surface due to the poor adhesion of such a metal to such a resin.
The description given hereinbefore has obviously been given in a non-limitative, illustrative manner and modifications are possible without passing beyond the scope of the invention. In particular, the X-ray protection material 16 may only cover the upper face l5 of the mechanical structure or only the side faces 17 thereof. In this case, the anti-SGEMP material 20 or 20a forming the outer surface of the box cover 4, covers all the X-ray material and that part of the rigid structure 14 not covered by X-ray protection material 16. Moreover, when the anti-SGEMP material is a poor electricity conductor, a faradization layer can be inserted between the anti-SGEMP layer 20a and those parts of the outer surface of structure 14 not covered by the X-ray protection material 16.
The protective means according to the invention can be used wherever electronic circuits have to be protected against X-rays. This protection makes it possible to withstand severe surrounding climatic and mechanical conditions. In particular, the invention applies when minimum weight conditions are required. Thus, the protective box according to the invention makes it possible, in the case of an equivalent filtering efficiency to that of a solid material sheet covering a metal mechanical structure, permits gains SP 3005.69 LC
. . .
~Z987QO
as regards weight and overall dimensions, as well as a reduction in manufacturing costs. Thus, the protective box according to the invention can be advantageously used for producing very high performance electronic means on-board aircraft.
SP 3005.69 LC
RESPECT TO X-RAYS
BACKGROUND OF THE INVENTION
The present invention relates to a protective box for electronic circuits hardened with respect to X-rays. It more especially applies to protecting high performance electronic circuits used in the aeronautical and space fields against X-rays.
High-performance electronic circ~its, both from the processing speed and the capacity standpoints, are very sensitive to the effects of X-rays. These effects can even lead to the destruction of the active components of the electronic circuits involving latch up phenomena.
Apart from the X-radiation dose or quantity received, a particularly important parameter isthat of the time during which said quantity is supplied. The dose associated with its application time is called the dose rate. The behaviour or resistance of the active components of the electronic circuits with respect to said parameters (dose, dose rate) and the energy spectrum of said radiation is essentially linked with the production technology thereof. In most cases, it is necessary to reduce the dose levels and rates in order to permit the electronic circuits to retain their functional integrity.
One of the most widely used methods for reducing doses and dose rates received by electronic circuits consists of SP 3005.69 LC
- lzss7ao enclosing them in an envelope made from a pure metal with a high atomic number. The metal and thickness of the metal sheet are chosen and adapted as a function of the energy of the X-radiation in question and the desired filtering rate.
This metal sheet effectively protects against high X-ray doses and dose rates. As a function of the circuits and/or technology of the electronic components, the need for protection can be felt as from 1 to 10 Krad and 105 to 107 rad.s.
Generally, the metal sheet covers a metal structure, particularly of light alloy, enclosing the electronic circuits, said structure providing the necessary mechanical strength and protection. The metal sheet is mechanically fixed over the entire outer surface of the metal structure.
Unortunately the realization of the most interesting metals for this type of protection is difficult and costly. Moreover, the requirements with respect to said protection materials and the guarantee that they will not deteriorate under various ionizing, mechanical and climatic surrounding conditions means that the weight breakdown of the electronic circuits is highly increased, compared with circuits which are not protected against X-rays.
In most cases, the metal sheet for protecting against X-rays cannot be engaged directly over the entire outer surfaces of the metal structure of the encapsulating box due to the SP 3005.69 LC
lZ98700 often complex profile thereof. This profile complexity is often imposed by heat dissipation constraints.
Therefore the volume defined by the metal protection sheet is greater than the volume of the mechanical structure to be protected. This leads to an increase in the weight and overall dimensions of the mechanical structure, which is further increased by the mechanical devices required for maintaining the metal sheet in place on the mechanical structure (spacers, angle brackets, screws, bolts, etc.).
In addition, these maintenance devices must be made from the same metal as the metal protection sheet, so as not to create "holes" in the protection against X-rays.
Furthermore, as the mechanical structure is made from a metal or alloy, this further increases the total weight of the box for encapsulating the electronic circuits.
It is clear that these disadvantages as regards the overall dimensions and weight of encapsulating boxes are particularly prejudicial with respect to the use of electronic circuits on-board aircraft.
Another method consists of directly depositing the X-ray protection metal on the mechanical structure to be protected either by impregnating the latter in a liquid bath, or by electrolysis. However, these deposition processes are not possible for all the metals usable for providing protection SP 3005.69 LC
.. ..... ... .. . . . . . . .
- ~Z9~700 against X-rays. Moreover, in this case it is al~o necessary to examine the corrosion compatibilities of the metals present.
In addition, the thicknesseg which can be deposited for the metals lending themselves to this procedure are limited, otherwise the deposit adhesion quality may be prejudiced.
Moreover, the obtaining of a homogeneous deposit makes it necessary to proceed in successive stages with further machining bet~een the deposits so that, in certain cases, the dimensions of the encapsulating box are respected in the final stage. Thus, these deposition methods are limited and lead to a high cost of the X-ray protection encapsulating boxes.
Another approach consists of envisaging a specific protection for each on-board electronic component, ~-hich constitutes a different and more advance solution compared with those referred to hereinbefore This specif~c protection described in FR-A-2 547 113, published on December 7,1984, consists of using several stacked layers of different materials having different atomic number~ (Z).
Materials with a high atomic number are dielectric ceramics, such as barium or neodymium titanate, titanium oxide or a complex lead-based ceramic. Materials having a low atomic number are carbon, aluminium, silicon, alumina and silica.
sP 3005 . 69 LC
1298';'~0 As n function of the applications and number Or componentQ
involved, the number of individual protections can be more disadvantageous from the weight standpoint than an overall protection of all the electronic components. Moreover, the technology for producing the different materials forming the piles or stacks is based on processes used for the production of capacitors and in particular fritting processes. In particular, the process described does not make it possible to obtain an X-ray protection material with a complex shape.
Within the framework of protecting persons working in the presence of X-rays, the materials mainly comprise a charge ~uch as lead, dispersed in an organic binder. Such protection materials are in particular described in FR-A-2 482 761, published on November 20, 1981 and Us-A-3 622 432 of H.K. Porter Company.
These lead-based materials can only be used as X-ray protection materials for radiation with a low flow rate a~sociated with relatively long dose distribution times.
( Another known electronic circuit encapsulating box is described in FR-A-2 490 917,` published on M~ch 26,1982. This box is made from a moulded plastic material, such as an epoxy resin, in which the electronic circuits are embedded.
This box is extremely thin and does not make it possible to effectively mechanically protect the electronic circuits.
SP 3005.69 LC
~4 lZ987~0 Moreover, there is no X-ray protection.
The present invention relates to a box for protecting electronic circuits hardened with respect to X-rays and making it possible to obviate the various disadvantages referred to hereinbefore. Compared with the use of a heavy metal sheet covering a metal structure, this protective box in particular leads to an important weight and overall dimension gain, whilst effectively protecting against radiation with a high dose rate and in particular exceeding those referred to hereinbefore.
MOreover, this protective box causes no major manufacturin~
problem and can be manufactured in a much shorter time than th~t necessary for manufacturing prior art encapsulating boxes.
Moreover, compared with FR-A-2 547 113, published on December 7, 15 1984, the invention makes it possible to bring about a development of the X-ray protection levels without any detrimental affect on the definition of the electronic circuits contained in the box.
SUMMARY OF THE INVENTION
The present invention specifically relates to a protective box for electronic circuits hardened with respect to X-rays, wherein it comprises at least one element formed from a rigid mechanical structure made from a composite material, constituted by a fibre-reinforced resin, and an X-ray SP 3005.69 LC
lZ98700 protection material at least partly covering the mechanical structure and which is formed from a resin matrix containing, in the form of a regularlydispersed powder, at least one metal and/or at least one inorganic compound of a metal, the powder only melting at a temperature at least equal to 630C and the metal having a high atomic number at least equal to 47.
In particular, the powder can be constituted by a metal and an inorganic compound of said same metal or another metal. This metal and this inorganic compound has a melting temperature equal to or above 630C.
The term element of the box is understood to mean any part used in the formation of the box, such as the cover or the base on which the cover is fixed, as well as part of the cover or base (case of a cover or base in several parts).
The X-ray protection must be associated with all the vi~ible faces of the box, bearing in mind the random directlon of X-rays.
The use of materials with high melting points makes it possible to avoid undesirable effects due to heat shocks caused within the material during X-radiation, such as the surface melting of the powder grains which can lead to the destruction of the protective material. Moreover, the use of a metal with a high atomic number equal to or greater than 47 permits an effective X-ray filtering.
SP 3005.69 LC
lZ9~71:?0 For an equal material quantity, the use of powder regularly distributed in a resin matrix leads to an efficiency loss compared with pure sheet metal, all other conditions being the same. As this efficiency loss is essentially a function of the grain size of the powder and the powder quantity in the organic binder, preference is given to a powder having a grain size between 0.5 and 25 ~m and e.g. between 1.6 and 10 ~um.
In the same way the powder quantity in the binder can range between 25 and 50% by volume of the finished X-ray protection material. The doping quantity of the organic binder in this range is a function of the sought X-ray protection efficiency.
This also applies with respect to the thickness of the X-ray protection material.
The resin used for forming the matrix of protective material can be a thermoplastic or thermosetting resin, whose heat expansion coefficient is compatible with that of the composite material forming the mechanical structure and whose polymerization catalyst is compatible with the resin of said composite material.
As a resin entering into the composition of the X-ray protection material, examples are polyamides, polyethers, polyesters, phenoplastics, polyolefines, epoxydes, polyimides, silicones, furans, etc.
The metal powder embedded in the organic matrix of the SP 3005.69 LC
129137~)0 _ 9 _ X-ray protection material can be a silver, antimony, barium, rare earth, tantalum, tungsten, rhenium, iridium, platinum, gold, uranium or hafnium powder or a powder formed from a mixture of these metals. Preference is given to the use of silver, tantalum, tungsten or uranium.
When the powder is formed by an inorganic component, the latter can be an oxide, a nitride or a carbide of a heavy metal, such as those referred to hereinbefore. In particular, the inorganic compound is an oxide, nitride or carbide of silver, tantalum, tungsten or uranium when said compound effectively exists.
In order to optimize the protection against X-rays over a very broad energy spectrum, it is possible to use one or more metals and/or one or more inorganic compounds of a metal.
The rigid mechanical structure is constituted by a material able to withstand the mechanical stresses which the final protective box is exposed. It can be formed from a thermoplastic or thermosetting resin reinforced by fibres.
However, in order to ensure an excellent mechanical strength, preference is given to the use of thermosetting resins, such as epoxy, phenolic, polyester, polyimide and furan resins.
The reinforcing fibres can he short or long and can be made from an organic or inorganic material, such as glass, carbon, boron, kevlar or metal.
SP 3005.69 LC
. . .
izg~700 _ 10 --This composite materinl (resin + fibres) has a den~ity between 1.2 and 1.8 instead Or 2.8 for aluminium. The weight gain of a rigid structure according to the invention i~
consequently significant.
The mechanical structure has a shape and size corresponding to the needs for fixing and housing the electronic circuits to be located there. It is obtained by moulding by injection, by compression or by a hybrid method called "compression-transfeF mouldin~". de~cribed in French patent application 0 2591525 published on March 23,1988.
On the thus obtained rigid structure is effected a potting of the X-ray protection material either by injection, or by compression. In order to ensure a good adhesion of the X-ray protection material to the mechanical structure, the latter can be pre~iously heated and/or can be subject to a surface preparation.
In order to obtain a good distribution of the powder in the organic binder forming the X-ray protection material for bringing about homogeneity of the opacity, prior to potting premixing takes place of the powder and binder. Thi~
premixing is performed either by mixing the po~-der with melted grains of resin and then forming mixture granules by extrusion, or by simply mixing the powders, or by mixing the powder in an organic liquid binder. This premix is then introduced in the mould to be polymerized on the - mechanical structure.
~, SP 3005.69 LC
lZg87~0 The production of the X-ray protection material by potting makes it possible to ensure a continuous, homogeneous adhesion of the material on the rigid mechanical structure.
This makes it possible to reduce the overall dimensions of the encapsulating box compared with the prior art solutions.
In order to improve the attachment of the X-ray protection material to the rigid mechanical structure, the latter can have slots formed during the moulding of the structure.
These slots are filled with X-ray protection material during the potting thereof, thus ensuring a sought supplementary attachment effect.
In order to prevent the emission of electrons by the walls or elements of the protection box during X-ray irradiation and in particular by the metal powder, the box element can be covered with a material formed from at least one element having a low atomic number, at the most equal to 6, at least partly constituting the outer or inner surface of said box element.
This material has a thickness exceeding the mean free travel of the electrons emitted by the walls of the box protected against X-rays during X-ray irradiation. It always forms the final layer with respect to the surrounding atmosphere.
The element with a low atomic number can be carbon, boron or beryllium.
SP ~005.69 LC
lZ987~0 The material for preventing the emissivity effects of the protective box walls iB generally known under the name anti-SGEMP material (System Generaling ElectroMagnetic Pulse). It can be in the form of a paint containing particles of the element with an atomic number at the most equal to 6 and is e.g. of Astral type Pyrofle~ 7D 713.
Advantageously, the considered element of the protective box is e~uipped with a material which is a good electricity conductor which serves to filter the electromagnetic waves other than the X-rays, whereby said material covers the outer surface of the assembly formed by the mechanical structure and the X-ray protection material and/or the inner surface of said mechanical structure. This good electricity conducting material constitutes a Faraday cage protecting the electronic circuits located in the protective box and will hereinafter be called a faradization material. The faradization material can be nickel, silver, pure aluminium, copper and beryllium. Beryllium has the advantage of being able to serve both as an anti-SGEMP material and as a Faraday cage, due to its low atomic number and its good electrical conductivity.
BRIEF DESCRIPTION OF THE DRAWTNGS
The invention is described in greater detail hereinafter relative to non-limitative embodiments and the attached drawings, wherein show:
Fig. 1 Diagrammatically in longitudinal section a first embodiment Or the protection means according to ~' SP 3005.69 LC
lZ98~ 0 the invention.
Fig. 2 Diagrammatically and in longitudinal section a second embodiment of the protection means according to the invention.
Fig. 3 Diagrammatically and in longitudinal section a third embodiment of the protection means according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
With a view to simplifying the description, the latter refers to a protective box formed from a monoblock cover fixed to base and formed by a single part, in which the element liable to be irradiated by X-rays is the box. The possible directions of the X-ray flux are represented by arrows F in figs. 1 to 3. As stated hereinbefore, the invention clearly has a much wider application.
Fig. 1 diagrammatically shows in longitudinal section a box for protecting electronic circuits having a base 2, on which is fixed a cover 4, e.g. using screws 6. This box receives electronic circuits 8. In particular, these circuits can be fixed by any known means to bosses 10 provided for this purpose on the inner face of the box cover 4. In very diagrammatic manner as it does not form part of the object of the invention, the electronic circuits 8 are connected to electrical circuits outside the box by conductive tracks indicated at 12 and which e.g. pass through the box space 2.
SP 3005.69 LC
129137(~0 The qpecific ~hape of the box, aq well as the fixing and connection of the electronic circuits located in the X-ray protection box are linked with the type of components uced.
These components can be encapsulated in boxes T0 5, T0 66, etc.
According to the invention, cover 4 has a rigid structure 14 ensuring the mechanical protection of the electronic circuits.
Structure 14 is formed from a thermosetting plastics material, such as bakelite, polyimide resin or silicones, reinforced by organic or non-organic fibres. Structure 14 is e.g.
made from KINEL 5504 marketed by Rhône Poulenc, said material being a polyimide resin reinforced by long glass fibres arranged in a random manner. This rigid structure 14 is formed by moulding, either by injection, or by compression, said procedures being well known to the Expert. It can have a thickness of 2 mm.
The protection against X-rays of the electronic circuits 8 located in the box is ensured with the aid of a layer material 16 in contact with the inner surface of the rigid structure 14 or, as ~hown in the drawing, in contact with the outer surface of the rigid structure.
The X-ray protection material 16 covers all the outer surface of structure 14 liable to be irradiated by X-rays.
In the case shown in fig. 1, the material layer 16 covers the entire outer surface of structure 14, namely upper face SP 3005.69 LC
lZ9~
15 and side faces 17 of sAid structure.
In order to ensure a good adhesion of the protective material 16 to rigid structure 14, the latter can have slots 18 formed during the moulding of the rigid structure 1~. These slots 18 are filled with X-ray protection material during the potting of the latter.
The X-ray protection material 16 is e.g. formed from a tungsten powder representing 30% by volume of the finished product and which is regularly dispersed in a PAll resin produced by ATOCHFM. This resin is a thermoplastic polyamide resin. The tungsten powder has an average grain size of 4 ~m, a dispersion of 2.5 and a purity of 99.9%.
This protective material can be obtained by melting granules of PAll resin, to which the tungsten powder is added. The premix obtained is introduced into a Werner~ ZSK30 extruder-granulator, in order to obtain mixture granules which can then be introduced into a mould already containing the ( rigid structure 14 to be covered by the X-ray protection material. The introduction of the mixture granules into the mould takes place by injection. The potting of the X-ray protection material is assured on rigid structure 14 heated in order to facilitate the adhesion of the X-ray material. The protective material obtained can have a thickness of 1.5 mm.
.7 ,~
~, SP 3005.69 LC
lZ98~7C~0 - 16 _ The moulding and potting respectively of rigid structure 14 and X-ray protection material 16 make it possible to directly obtain protective box covers with the requisite dimensions and accuracies without further machining being required. Moreover, these moulding procedures are particularly advantageous from the financial and manufacturing time standpoints, because the runs of box covers to be produced make it possible to reduce the costs of specific tools for each box model.
The X-ray protection material can also be constituted by a powder containing 6% by volume of tungsten and 240~ by volume of uranium dioxide (U02) embedded in P~ll resin.
This material can have a thickness of 2 mm, in order to ensure effective filtering.
In the same way, the PAll polyamide resin can be replaced by a polyether block amide resin, such as that marketed under the trade name DINYL by Rhône-Poulenc. The resin of protective material 16 can also be bakelite or silicone.
To avoid raising the electromagnetic level due to electron emission by the outer walls of the protective box during X-ray irradiation and in particular by the metal contained in the X-ray protection material 16, an anti-SGEMP material 20 forming the outer surface of cover 4 can be provided.
In the case shown in fig. 1, material 20 covers the entire X-ray protection material 16. It is made from beryllium so SP 3005.69 LC
lZ98700 that, apart from the anti-SGEMP function, itprovides the necessary protection of electronic circuits 8 against electromagnetic waves.
The closing of the Faraday cage is obtained for the case described here by the presence of base 2 made or covered by a good electricity conducting metal, such as nickel, silver, aluminium, beryllium or copper. Material 20 must have a thickness exceeding the free mean travel of the electrons emitted by the walls of the cover and also constitutes a covering for the final layer. In particular, in the case of an X-ray protection material covering the inner surface of the mechanical structure, the anti-SGEMP material advantage-ously constitutes the internal surface of the cover. It is possible to envisage the simultaneous use of an anti-SGEMP
layer constituting the inner surface of the box and an anti-SGEMP layer constituting the outer surface of the box.
Fig. 2 shows a second embodiment of the protective means according to the invention, in which the material used for preventing the emissivity effects of the walls of the case exposed to X-rays and in particular material 16 is made from a poor electricity conductor, such as carbon or boron.
Under these conditions, the protection of integrated circuits 8 against electromagnetic waves is not assured.
In order to assure this protection, the inner surface of the rigid structure 14 is completely covered with a good SP 3005.69 LC
electricity conducting layer 22. In particular layer 22 is made from a metal, such as nickel or silver. Layer 22 has a thickness of approximately 0.1 mm. The other parts of the protective box and in particular cover 4 are unchanged compared with fig. 1.
Fig. 3 shows a third embodiment of the protective box according to the invention. This embodiment differs from that of fig. 2 only in that the layer serving as the Faraday cage is positioned between the anti-SGEMP material layer 20a and the X-ray protection material layer 16. Layer 24 has a thickness of 0.1 mm and is`in particular made from silver or nickel.
As in the case of fig. 1, the Faraday cage is closed by the presence of base 2 made from a metal or covered with-a metal which is a good electricity conductor.
In order to simplify the manufacture of the protective boxaccording to the invention and ensure a good insulation of the electronic circuits 8 against electromagnetic waves, it is possible to provide a faradization layer 22-24 covering both the inner face of mechanical structure 14 (fig. 2) and the outer surface of the X-ray protection material 16 (fig. 3). This can be carried out by simply immersing the mechanical structure 14 coated with protective material 16 in a bath containing the metals to be deposited to serve as a Faraday cage (chemical deposition).
SP 3005.69 LC
It should be noted that the metal faradization layer cannot be applied to a silicone surface due to the poor adhesion of such a metal to such a resin.
The description given hereinbefore has obviously been given in a non-limitative, illustrative manner and modifications are possible without passing beyond the scope of the invention. In particular, the X-ray protection material 16 may only cover the upper face l5 of the mechanical structure or only the side faces 17 thereof. In this case, the anti-SGEMP material 20 or 20a forming the outer surface of the box cover 4, covers all the X-ray material and that part of the rigid structure 14 not covered by X-ray protection material 16. Moreover, when the anti-SGEMP material is a poor electricity conductor, a faradization layer can be inserted between the anti-SGEMP layer 20a and those parts of the outer surface of structure 14 not covered by the X-ray protection material 16.
The protective means according to the invention can be used wherever electronic circuits have to be protected against X-rays. This protection makes it possible to withstand severe surrounding climatic and mechanical conditions. In particular, the invention applies when minimum weight conditions are required. Thus, the protective box according to the invention makes it possible, in the case of an equivalent filtering efficiency to that of a solid material sheet covering a metal mechanical structure, permits gains SP 3005.69 LC
. . .
~Z987QO
as regards weight and overall dimensions, as well as a reduction in manufacturing costs. Thus, the protective box according to the invention can be advantageously used for producing very high performance electronic means on-board aircraft.
SP 3005.69 LC
Claims (11)
1. A protective box for electronic circuits hardened with respect to x-rays, said protective box comprising a molded rigid mechanical structure of composite material constituted by a fiber-reinforced resin;
an x-ray protection material covering at least parts of said mechanical structure capable of being irradiated by x-rays, said x-ray protection material being potted on said mechanical structure and composed of a resin matrix containing a regularly dispersed powder consisting of at least one metal and/or at least one inorganic compound of a metal, said powder having a melting temperature at least equal to 630°C, said metal and/or metal of the inorganic compound having a high atomic number at least equal to 47; and an anti-SGEMP material which at least partly covers the outer and/or inner surface of the mechanical structure.
an x-ray protection material covering at least parts of said mechanical structure capable of being irradiated by x-rays, said x-ray protection material being potted on said mechanical structure and composed of a resin matrix containing a regularly dispersed powder consisting of at least one metal and/or at least one inorganic compound of a metal, said powder having a melting temperature at least equal to 630°C, said metal and/or metal of the inorganic compound having a high atomic number at least equal to 47; and an anti-SGEMP material which at least partly covers the outer and/or inner surface of the mechanical structure.
2. A protective box according to claim 1, wherein the powder represents 25 to 50% by volume of the x-ray protection material.
3. A protective box according to claim 1, wherein the high atomic number metal is selected from the group consisting of silver, tantalum, tungsten and uranium.
4. A protective box according to claim 1, wherein the anti-SGEMP material includes at least one chemical element with a low atomic number at the most equal to 6.
5. A protective box according to claim 4, wherein the low atomic number element is selected from a group consisting of carbon, boron and beryllium.
6. A protective box according to claim 1, including an electrically conducive material covering the outer surface of the assembly composed of the mechanical structure ant the x-ray protection material.
7. A protective box according to claim 1, including a material which is electrically conducive covering the inner surface of the mechanical structure.
8. A protective box according to claim 7, wherein the electricity conducting material is selected from the group consisting of nickel,silver, aluminium, beryllium and copper.
9. A protective box according to claim 1, wherein the mechanical structure is provided on its surface covered with the x-ray protection material with slots for improving the adhesion of said material to the mechanical structure.
10. A protective box according to claim 1, wherein the composite material constituting the mechanical structure is formed from a thermosetting resin.
11. A protective box according to claim 1, wherein said anti-SGEMP material has a thickness exceeding the free mean path of electrons emitted during an x-ray irradiation of said box.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8605442A FR2597652B1 (en) | 1986-04-16 | 1986-04-16 | ELECTRONIC CIRCUIT PROTECTION BOX, HARDENED AGAINST X-RAYS |
| FR8605442 | 1986-04-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1298700C true CA1298700C (en) | 1992-04-14 |
Family
ID=9334293
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000534534A Expired - Fee Related CA1298700C (en) | 1986-04-16 | 1987-04-13 | Protective box for electronic circuits hardened with respect to x-rays |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4833334A (en) |
| EP (1) | EP0242295B1 (en) |
| JP (1) | JPS62255893A (en) |
| CA (1) | CA1298700C (en) |
| DE (1) | DE3768543D1 (en) |
| ES (1) | ES2020572B3 (en) |
| FR (1) | FR2597652B1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4115043A1 (en) * | 1991-05-08 | 1997-07-17 | Gen Electric | High density interconnect structure for packaging microwave and other overlay sensitive chips |
| GB2279803B (en) * | 1990-04-05 | 1995-05-24 | Gen Electric | A high density interconnect structure including a chamber |
| US5236101A (en) * | 1990-10-18 | 1993-08-17 | Dugmore Peter B | Radiation proof tamper-indicating container |
| US5324952A (en) * | 1992-07-10 | 1994-06-28 | Ball Corporation | Radiation shielding for spacecraft components |
| US5880403A (en) | 1994-04-01 | 1999-03-09 | Space Electronics, Inc. | Radiation shielding of three dimensional multi-chip modules |
| US5825042A (en) * | 1993-06-18 | 1998-10-20 | Space Electronics, Inc. | Radiation shielding of plastic integrated circuits |
| US6613978B2 (en) * | 1993-06-18 | 2003-09-02 | Maxwell Technologies, Inc. | Radiation shielding of three dimensional multi-chip modules |
| US5635754A (en) * | 1994-04-01 | 1997-06-03 | Space Electronics, Inc. | Radiation shielding of integrated circuits and multi-chip modules in ceramic and metal packages |
| US6720493B1 (en) | 1994-04-01 | 2004-04-13 | Space Electronics, Inc. | Radiation shielding of integrated circuits and multi-chip modules in ceramic and metal packages |
| US6261508B1 (en) | 1994-04-01 | 2001-07-17 | Maxwell Electronic Components Group, Inc. | Method for making a shielding composition |
| US6455864B1 (en) | 1994-04-01 | 2002-09-24 | Maxwell Electronic Components Group, Inc. | Methods and compositions for ionizing radiation shielding |
| US5986276A (en) * | 1994-06-23 | 1999-11-16 | Labriola, Ii; Donald P. | Apparatus and method for eliminating X-ray hazards from electrical power distribution fields |
| JP3492425B2 (en) * | 1994-08-26 | 2004-02-03 | 大日本印刷株式会社 | X-ray shielding laminate |
| DE19600770C2 (en) * | 1996-01-11 | 1997-11-13 | Ibm | Security film with EMC protection |
| BR9710080A (en) | 1996-06-28 | 2000-01-11 | Texas Research Inst Austin | Composition of high density matter. |
| WO1998059345A1 (en) * | 1997-06-23 | 1998-12-30 | Stefan Marek | Ecological antigeopathic screen |
| EP1105357A2 (en) * | 1998-08-21 | 2001-06-13 | Siemens Aktiengesellschaft | Radiation protective concrete and radiation protective casing |
| US6594156B1 (en) * | 2000-04-24 | 2003-07-15 | Minimed Inc. | Device and method for circuit protection during radiation sterilization |
| JP2001208891A (en) * | 2000-01-24 | 2001-08-03 | Space Syst Loral Inc | Laminated lightweight radiation shielding material |
| US6368899B1 (en) * | 2000-03-08 | 2002-04-09 | Maxwell Electronic Components Group, Inc. | Electronic device packaging |
| WO2002044277A1 (en) * | 2000-12-01 | 2002-06-06 | Kanebo, Limited | Molded resin for radiation shielding |
| US6605818B1 (en) | 2002-03-28 | 2003-08-12 | The Boeing Company | Method for protecting against ionizing radiation using a sprayed protective coating, and a protected structure |
| US7382043B2 (en) * | 2002-09-25 | 2008-06-03 | Maxwell Technologies, Inc. | Method and apparatus for shielding an integrated circuit from radiation |
| US7163752B2 (en) * | 2002-12-19 | 2007-01-16 | The Boeing Company | Shielded system with a housing having a high atomic number metal coating applied by thermal spray technique |
| US7191516B2 (en) * | 2003-07-16 | 2007-03-20 | Maxwell Technologies, Inc. | Method for shielding integrated circuit devices |
| US8492762B2 (en) * | 2006-06-27 | 2013-07-23 | General Electric Company | Electrical interface for a sensor array |
| US8720724B1 (en) | 2008-07-18 | 2014-05-13 | The United States Of America As Represented By The Secretary Of The Navy | Protective cover assembly for electronics |
| CN102479563A (en) * | 2011-06-30 | 2012-05-30 | 上海西门子医疗器械有限公司 | Anti-radiation material and CT (computed tomography) chassis |
| JP6205268B2 (en) * | 2011-09-14 | 2017-09-27 | グンゼ株式会社 | Radiation protection fabric |
| CN102529239B (en) * | 2011-11-21 | 2014-12-10 | 南京航空航天大学 | Laminated neutron radiation shielding composite material and preparation method thereof |
| CN112509720B (en) * | 2020-11-26 | 2021-10-01 | 哈尔滨工业大学 | Cyanate ester radical anti-irradiation reinforced conformal coating and preparation method thereof |
| WO2022208869A1 (en) * | 2021-04-02 | 2022-10-06 | 三菱電機株式会社 | Power semiconductor device |
| CN113552402B (en) * | 2021-07-09 | 2022-12-23 | 清华大学 | Device for measuring coupling current |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1844512A (en) * | 1929-10-11 | 1932-02-09 | Westinghouse Electric & Mfg Co | Laminated material |
| NL187314B (en) * | 1953-05-15 | Toyama Chemical Co Ltd | ANTIBACTERIAL PREPARATION, AS WELL AS A SUBSTITUTED IN SITE 1 7- (3-AMINOPYRROLIDINO) -6-FLUOR-4-OXO-1,4-DIHYDRO-1,8-NAPHTYRIDINE-3-CARBONIC ACID DERIVATE. | |
| US2928948A (en) * | 1955-05-23 | 1960-03-15 | Herman I Silversher | Laminar ray resistant materials |
| US3622432A (en) * | 1967-02-01 | 1971-11-23 | Porter Co Inc H K | Flexible ionizing radiation shield barriers |
| GB2007480A (en) * | 1977-10-20 | 1979-05-16 | Lintoff Eng Ltd | Radiation shielding |
| FR2547113B1 (en) * | 1983-06-03 | 1986-11-07 | Inf Milit Spatiale Aeronaut | ELECTRONIC COMPONENT ENCAPSULATION BOX, RADIATION HARDENED |
| JPS60134448A (en) * | 1983-12-23 | 1985-07-17 | Nippon Telegr & Teleph Corp <Ntt> | Package for semiconductor device |
| JPS60186040A (en) * | 1984-03-05 | 1985-09-21 | Toshiba Corp | Electronic part |
| FR2584863B1 (en) * | 1985-07-12 | 1988-10-21 | Inf Milit Spatiale Aeronaut | ELECTRONIC COMPONENT HARDENED WITH RESPECT TO RADIATION |
-
1986
- 1986-04-16 FR FR8605442A patent/FR2597652B1/en not_active Expired
-
1987
- 1987-04-08 US US07/035,981 patent/US4833334A/en not_active Expired - Fee Related
- 1987-04-13 CA CA000534534A patent/CA1298700C/en not_active Expired - Fee Related
- 1987-04-14 ES ES87400850T patent/ES2020572B3/en not_active Expired - Lifetime
- 1987-04-14 DE DE8787400850T patent/DE3768543D1/en not_active Expired - Fee Related
- 1987-04-14 EP EP87400850A patent/EP0242295B1/en not_active Expired - Lifetime
- 1987-04-15 JP JP62092958A patent/JPS62255893A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62255893A (en) | 1987-11-07 |
| DE3768543D1 (en) | 1991-04-18 |
| EP0242295A1 (en) | 1987-10-21 |
| FR2597652A1 (en) | 1987-10-23 |
| FR2597652B1 (en) | 1988-07-29 |
| US4833334A (en) | 1989-05-23 |
| EP0242295B1 (en) | 1991-03-13 |
| ES2020572B3 (en) | 1991-08-16 |
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