WO2013056818A1

WO2013056818A1 - Contacting of an antenna

Info

Publication number: WO2013056818A1
Application number: PCT/EP2012/004324
Authority: WO
Inventors: Michael Baldischweiler; Carsten Bohn
Original assignee: Giesecke & Devrient Gmbh
Priority date: 2011-10-18
Filing date: 2012-10-16
Publication date: 2013-04-25
Also published as: DE102011116259A1; EP2769602A1

Abstract

In order to create a cohesive metallic connection between a connection face (8) of an antenna (3) arranged on a card-like substrate (2) and a contact face (5) of an electronic module (4), a multi-layer contact film (10) is arranged in a manner adjoining the connection face (8) of the antenna (3). The multi-layer contact film (10) is a contact film which is produced at least from a plurality of layers that are less than a micron thick, adjoin one another and are composed of materials that react exothermically with one another, in particular what is known as a "nanofilm". Following the arrangement of the multi-layer contact film (10), the exothermic reaction in the multi-layer contact film (10) is initiated by "igniting" the multi-layer contact film, thereby creating the cohesive metallic connection.

Description

C o n t a c t i o n c e a n e s e n e s

The present invention relates to an electronic component group comprising a card-shaped substrate with an antenna arranged thereon and an electronic component, wherein a cohesive metallic connection is formed between a connection surface of the antenna and a contact surface of the electronic component, and a method for producing such a cohesive metallic connection , In addition, the present invention relates to a correspondingly adapted card-shaped substrate and a correspondingly adapted electronic component.

It is known to electrically connect connecting surfaces of an antenna arranged on a chip card substrate, for example an antenna printed on the substrate, with contact surfaces of a corresponding electronic component by soldering or by means of silver conductive paste. However, it can be difficult to ensure that the pad of the antenna does not oxidize before contacting. As a result, there may not be any permanent, stable electrical contact. In addition, such contact surfaces can be connected via vias, which pass through recesses of the smart card substrate. For this purpose, after printing the antenna from the opposite side of the substrate, a recess extending up to the antenna through the substrate is produced. In order to contact the antenna through this recess, subsequently printed conductors made of silver conductive paste are then printed on the side opposite the antenna in such a way that the recess is filled up with the silver conductive paste. However, residues of the substrate material or else other substances used to produce the recess frequently remain on the substrate the recess has exposed connection surfaces of the antenna. This can also lead to the result that no reliable electrical contact. These disadvantages are not completely eliminated even when forming a solder joint.

The object of the present invention is therefore to ensure a reliable electrical contact when contacting an antenna by simple means. This object is achieved by an electronic component group, a production method for such an electronic component group, a card-shaped substrate with an antenna arranged thereon, a suitably designed electronic module and a method for connecting the electrical connection surface of an antenna arranged on a card-shaped substrate to an electrical contact surface of an antenna Electronic components solved via a cohesive metallic connection according to the features of the independent claims. In dependent claims advantageous embodiments and developments of the invention are given. According to the present invention, at least one multilayer contact foil is arranged adjacent to the connection surface of the antenna for producing the material-locking metallic connection between the electrical connection surface of an antenna arranged on a card-shaped substrate and an electrical contact surface of an electronic component, eg a microchip or other semiconductor component. This film is then ignited to form the cohesive metallic compound. This multilayer contact foil is a layer of mutually adjacent layers of mutually exothermically reacting materials of less than one micrometer thickness. put contact foil. The layers are particularly preferably less than 500 nm or <200 nm or <100 nm or <50 nm or even <30 nm thick. Such contact sheets are available from Clinton, New York, US based Indium Corporation under the name "Nanofoil®".

The contact sheets are ignited by local heating to, for example, more than 250 ° C, whereby the materials of the adjacent layers begin to exothermically react with each other. As a result, the contact foil heats to a very high temperature (e.g.

1500 ° C), which is sufficient to weld the connection surface of the antenna with the multilayer contact foil and / or - in the presence of a solder - to solder. According to a preferred embodiment, tinned multi-layer contact films are therefore used. The material-coherent metallic connection accordingly comprises at least one such ignited multi-layer contact foil adjoining the connection surface of the antenna.

It has been found that a cohesive metallic connection produced by means of such a multilayer contact foil ensures reliable electrical contact with the connection surface of the antenna, even if the connection surface is oxidized.

In addition, it has been found that by means of the multilayer contact foil, a reliable electrical contact with the connection surface of the antenna can also be produced if the connection surface is contaminated with residues of the substrate material or other substances used in creating a recess over the connection surface and / or possibly oxidized , Accordingly, in a preferred embodiment, the antenna is disposed on a first side of the substrate, and from a second side opposite the first side, a recess extending up to the antenna is created through the substrate. The multi-layer contact foil is then arranged within this recess and the cohesive metallic compound is formed in the recess as a via through the substrate.

As already mentioned above, it is important for the invention that the multilayer contact foil adjoin the connection surface of the antenna. Otherwise, no reliable contact is made with this pad. However, the multilayer contact film does not have to be adjacent to the contact surface of the electronic component. Rather, a reliable electrically conductive connection can be generated between the multilayer contact film and the contact surface of the electronic component using conventional methods. Accordingly, the cohesive metallic connection according to a preferred embodiment between the multi-layer contact foil and the contact surface of the electronic component comprises a further metallic material, preferably silver conductive paste.

In particular, in the above-described preferred embodiment in which the antenna is disposed on a first side of the substrate and a recess for via is provided in the substrate, after disposing the multi-layer contact foil in the recess, the further metallic material may be provided on the first Side opposite side of the substrate so applied, in particular imprinted, that it fills the recess. Nevertheless, according to an alternative embodiment, the multilayer contact foil can of course also adjoin the contact surface of the electronic component. In this case, the entire cohesive metallic connection between the connection surface of the antenna and the contact surface of the electronic component is formed by the multilayer contact foil. This can be useful, in particular, if the electronic component and the antenna are arranged on the same side of the substrate. In principle, however, a via can also be created only by means of the multilayer contact foil, for example in the case of a correspondingly thin substrate.

As previously explained, the multilayer contact foil must be ignited to form the integral metallic compound, i. it must be heated sufficiently fast to a sufficiently high ignition temperature (e.g., 250 ° C). This can be achieved by light radiation, e.g. by means of a laser. Likewise, in principle, ignition by means of a hot firing pin is possible. However, in many embodiments, the multilayer contact film is not accessible from the outside in such a way that it could be ignited by means of a laser or a firing pin.

According to a preferred embodiment, the ignition takes place in such cases, for example by introduction into an electromagnetic field. In this case, the multilayer contact foil exposed to the electromagnetic waves and possibly adjacent electrically conductive materials such as an antenna (or antennas) act and heat up due to induced electrical currents.

Preferably, the multi-layer contact film is formed coil-shaped, wherein the resonance frequency can be determined by suitable measures. The coil-shaped multi-layer contact foil can be such be configured such that one or more areas in relation to the conductor cross-section of the remaining coil areas have a significantly reduced conductor cross-section. Preferably, the significantly reduced interconnect cross section is less than 50% of the interconnect cross section of the remaining coil regions, more preferably less than 10%. When a current threshold is exceeded, the heat development in the regions with a significantly reduced conductor cross-section is so high that the multilayer contact foil ignites in these regions. The arrangement of the region or areas with reduced conductor cross-section may vary depending on the embodiment. The arrangement leads in the manner of a fuse to the fact that in the aforementioned areas, the multilayer contact film forms a cohesive metallic connection to the pad of the arranged on the substrate antenna. The electromagnetic field is preferably evaluated with regard to the electrical conductivity of the metallically cohesive connection produced by the multilayer contact foil. Because the ignition of the multilayer contact foil and the resulting formation of the cohesive metallic connection change the resistance of the multilayer contact foil, the contact resistance to the connection surface of the antenna arranged on the substrate and the contact resistance to the further metallic material or the contact surface of the electronic component. These changes in resistance may cause a detectable change in the modulation of the applied electromagnetic field. Based on this modulation, accordingly, the quality of the metallurgically bonded connection can be evaluated.

The ignition of the multilayer contact foil, however, can not only be achieved by generating electrical currents in the multilayer contact foil by means of Magnetic radiation but also by differently generated electrical currents. In embodiments in which the multilayer contact foil is arranged in a through-contacting recess in the substrate, the electric current is preferably applied by means of a first sliding contact on the first side of the substrate on which the antenna is located and a second sliding contact on the first side opposite the second side of the substrate.

Also in this case, the electric current conducted by the multilayer contact foil can be controlled by the

Multilayer contact film produced cohesive metallic compound are evaluated, namely simultaneously with or following the welding and / or soldering. As stated above, the ignition of the multilayer contact film causes a change in the resistance of the multi-layer contact foil and the transition states to the contact surface of the antenna and to the further metallic material or the contact surface of the electronic component. Accordingly, on the basis of the electrical conductivity of the material-conclusive metallic compound their quality can be evaluated.

The multilayer contact film can first be arranged on a connection surface of the antenna prior to production of the cohesive metallic connection or - if the entire cohesive metallic connection to be produced is to be provided by the multilayer contact foil - on the contact surface of the electronic component. Accordingly, the present invention also relates to corresponding semi-finished products. In particular, the present invention therefore relates to a substrate having an antenna arranged thereon with at least one connection surface on which the multilayer contact foil is arranged. It is according to a preferred Ausführungsf orm the antenna disposed on one side of the substrate and the multi-layer contact foil in a recess of the substrate as part of a through hole to be produced through the substrate. Likewise, the present invention relates to an electronic component with at least one contact surface for contacting an antenna, on which at least one multilayer contact foil is arranged.

Further features and advantages of the invention will become apparent from the following description of exemplary embodiments according to the invention and further alternative embodiments in conjunction with the drawings, which show schematically:

FIG. 5 shows a card-shaped substrate with an antenna arranged thereon and a microchip connected to the antenna according to a first embodiment,

FIG. 2 shows a card-shaped substrate with an antenna arranged thereon and a microchip connected to the antenna according to a second embodiment,

Figure 3: the card-shaped substrate with arranged thereon antenna

Figure 1 with arranged on the contact surfaces of the antenna

Multilayer contact films and

FIG. 4 shows the microchip from FIG. 2 with multilayer contact films arranged on the contact surfaces.

1 shows an electronic component group 1 comprising a card-shaped substrate 2 with an antenna 3 printed on the underside of the substrate 2 and a microchip 4 arranged on the upper side of the substrate 2. The card-shaped substrate 2 may be, for example, a chip card substrate, a film or a chip card substrate film, for example a Card inlay, act. In the present case, the antenna 3 is shown schematically with only a single turn, but usually such printed antennas 3 have several turns. The substrate 2 is shown cut at the front edge in the perspective view to show the through-connection of the antenna 3 through the substrate 2.

The electronic component group 1 comprises other components, not shown. The electronic component group 1 may in particular be an RFID system, such as e.g. an RFID-ID card (Radio Frequency Identification card), an RFID SD card (Secure Digital card with RFID module), an RFID SD card (micro Secure Digital card with RFID card) Module), an RFID USB stick (USB stick with RFID module), an RFID key fobs (key fob with RFID module), an RFID security token (device for identifying and authenticating users with a RFID module), another device with an RFID module or even another device with an antenna or a component of one of the above-mentioned devices.

For through-contacting the antenna 3, recesses 7 are provided in the substrate 1, which extend from the upper side of the substrate 1 to the antenna 3 printed on the underside of the substrate 2. The corresponding freed from the substrate material surfaces 8 of the antenna 3 serve as pads 8 of the antenna 3. Instead of a printed antenna 3, a wound antenna can be used, the winding wire is connected, for example, to corresponding arranged on the underside of the substrate 2 pads. Likewise, an antenna 3 generated by an etching process on the underside of the substrate 2 can also be used. Likewise, the antenna can by any further, from the State of the art known to those skilled in the process are produced, for example by laser.

In the representation according to FIG. 1, the recesses 7 are arranged in the region of the section through the substrate 2, and it is therefore not apparent that the recesses 7 do not adjoin an outer edge of the substrate 2. The recesses 7 may e.g. be generated by a laser, by milling or by etching. It may happen that residues of the substrate material or even residues of a substance used in the production of the recesses 7, such as. an etchant, remain on the pads 8. In addition, the pads 8 oxidize in contact with air.

Nevertheless, in order to reliably electrically contact the possibly contaminated or oxidized connection surfaces 8 of the antenna 3, a multi-layer contact foil 10 is arranged adjacent to the connection surfaces 8 and ignited in a later method step. Arranging takes place by means of a placement machine, wherein a plurality of multilayer contact films 10 can be provided on rolls. As mentioned above, multilayer contact films 10 comprise several less than one micron thick contiguous layers of exothermally reactive materials and are known by the name of "nanofoil". They can be used to create soldered or welded joints and are characterized by the fact that in them a strong exothermic reaction can be triggered. This is also referred to as igniting the multi-layer contact film 10. Due to the highly exothermic reaction, the multi-layer contact film 10 is heated suddenly to a relatively high temperature (eg 1500 ° C), which is sufficient to weld metal surfaces together or - in the presence of a solder - to solder. Accordingly, the multilayer contact film 10 may have a solder layer on one or both sides in addition to the exothermically reacting layers. The ignition of the film can, for example, by rapid heating (at least one point) over a minimum temperature of eg 200 ° C or 250 ° C take place. Known multilayer contact films 10 consist of alternating thin layers of metals or semimetals, eg alternating layers of aluminum and nickel, of aluminum and titanium or of titanium and amorphous silicon. Typical layer thicknesses are, for example, 50 nm per layer pair, and the total thickness of such a multilayer contact film can be, for example, 60 to 150 micrometers. The nickel and aluminum layers form a nickel-aluminum compound after ignition.

Due to the high temperatures achieved for a short time, a reliable electrical contact with the connection surfaces 8 is created due to the welding, even if they are oxidized or contaminated to a certain extent.

The multilayer contact films 10 in the present exemplary embodiment do not adjoin corresponding contact surfaces 5 of the microchip 4. Rather, in addition to the top of the substrate 2 made of conductive silver conductor tracks 6 are applied, in particular imprinted. These interconnects 6 extend as far as the recesses 7, so that when the silver conductive paste is applied to the upper side of the substrate, the recesses 7 above the multilayer contact films 10 have been filled with the silver conductive paste.

On the interconnects 6, the microchip 4 is applied, for example, soldered, that between the contact surfaces 5 of the chip 4 and the interconnects 6, a metallurgical cohesive connection is formed. After application of the chip 4, the two multi-layer contact films 10 were ignited in the recesses 7. In this case, the multilayer contact films 10 form a reliable electrical contact both to the respective connection surface 8 and to the respective conductor track 6. The ignition took place in the present case, by means of ignition contacts 20 and a power source 21, an electrical direct or alternating current through the multilayer contact film 10 is passed. The ignition contacts 20 may in particular also be sliding contacts, and the current source 21 may be, for example, a battery.

To ignite a multi-layer contact foil 10, even small voltages of less than one volt normally suffice. Because corresponding, preferably solder-coated, multilayer contact films 10 typically have only a very low volume resistivity of e.g. 0.2 ohms, even at such low voltages, large currents flow and the generated heat triggers the ignition of the multilayer contact foil 10 after a very short time (for example, less than one millisecond).

On the basis of the current flow through the ignition contacts 20 through the multi-layer contact foil 10 can also be controlled whether the multi-layer contact foil 10 was ignited. In this case, e.g. already be evaluated during the ignition of the current flow. The ignition of the multilayer contact foil 10 and in particular the subsequent welding and / or

Soldering the multilayer contact foil 10 to the pad 8 normally causes a well detectable change in this current flow. E- benso may possibly even after the ignition on the basis of a current flow through the ignition contacts 20 through the multi-layer contact film 10 therethrough f estgestellt whether the multilayer contact film 10 was ignited and the pads 8 were soldered or welded to the multilayer contact film 10. The ignition and welding or soldering of the multilayer contact film 10 with the pads 8 usually causes a permanent measurable on the basis of the current flow resistance change.

Alternatively, the multilayer contact film 10 can also be ignited by the action of an electromagnetic field. By targeted irradiation with electromagnetic radiation electric currents are induced in the Mehrschichtkontaktfo- lie 10 and possibly in adjoining metallic components that heat the multi-layer contact film 10 and ignite. In this case, at the same time a modulation of the acting electromagnetic field with respect to the electrical conductivity of the generated by the multi-layer contact foil 10 metallurgically cohesive connection can be evaluated to verify in this way, in turn, the success of the welding or soldering.

Another alternative is to irradiate the multilayer contact film using electromagnetic waves, such as e.g. a laser, microwaves UV radiation, etc. The introduced radiation leads to ignition and subsequent welding or soldering.

In principle, the ignition could also be effected by means of a hot firing needle or by a force, e.g. by impact on the area of the substrate 2 in which the multilayer contact film 10 is arranged.

FIG. 2 shows a modification of the electronic component group 1. In this case, the antenna 3 and the microchip 4 connected to the antenna 3 are arranged on the same side of the substrate 2. plated through ments are not planned. The contact surfaces 5 of the microchip 4 are connected via ignited multilayer contact films 10 directly to the pads 8 of the antenna 3. The cohesive metallic compounds are accordingly formed only by the multilayer contact films 10. The ignition can be carried out in analogy to the embodiment shown in Figure 1 by passing an electric current through the respective multi-layer contact foil 10 by means of two ignition contacts. In the exemplary embodiment of FIG. 2, the two ignition contacts can, for example, contact a region of the connection surface 8 of the antenna 3 not covered by the contact film 10 and a foot 9 of the chip 4 electrically connected to the contact surface 5 of the chip 4. Likewise, in analogy to the embodiment of Figure 1 ignition by the action of an electromagnetic field is possible. Furthermore, the multilayer contact foil 10, which is more easily accessible in the exemplary embodiment of FIG. 2, can also be ignited by the action of heat, for example by means of a hot ignition needle, by means of a laser or by the action of force.

In a method for producing the cohesive metallic compound, therefore, the substrate 2 together with the antenna 3 and the microchip 4 are initially provided. Subsequently, if necessary, a recess 7 is created for a via. In addition, it is also possible to apply a corresponding solder or solder, in particular to or in the region of the connection surface 8 of the antenna 3, to the multilayer contact film 10 or to or in the region of the contact surface 5 of the chip 4. Subsequently, the multilayer contact film 10 is adjacent arranged on the pad 8 of the antenna 3. Thereafter, if necessary, conductor tracks 6 are applied. Then the chip 4 is arranged on the substrate 2 and then the multilayer contact foil 10 is ignited. det. After or during the ignition process, the quality of the coherent metallic connection can be checked.

Alternatively, for example, in the embodiment in which conductor tracks 6 are applied to the upper side of the substrate 2, the chip 4 may also be connected to the conductor tracks only after the multi-layer contact foil 10 has been fired.

The present invention also relates to corresponding semi-finished products, i. in particular the substrate 2 shown in FIG. 3 and belonging to the embodiment in FIG. 1 with antenna 3 arranged thereon and recesses 7 over the connection surfaces 8, wherein a multilayer contact film 10 is already arranged in each of the recesses 7. Likewise, the present invention also relates to the microchip 4 shown in Figure 4, belonging to the embodiment in Figure 2 with contact surfaces 5 for contacting an antenna, on each of which a multi-layer contact film 10 is arranged.

Claims

P a te n t a n s p r e c e s 1. Electronic component group (1) comprising:

a card-shaped substrate (2) with an antenna (3) arranged thereon with at least one electrical connection surface (8) and

an electronic component (4) having at least one electrical contact surface (5), wherein a cohesive metallic connection is formed between the connection surface (8) of the antenna (3) and the contact surface (5) of the electronic component (4),

characterized in that the cohesive metallic connection comprises at least one ignited multi-layer contact foil (10) which adjoins the connection surface (8) of the antenna (3) and which is at least of several microns thicker than one another adjacent to one another

Layers of mutually exothermically reacting materials is produced.

Second electronic component group (1) according to claim 1, characterized in that the antenna (3) on a first side of the substrate (2) and the E- lektronikbaustein (4) on a first side opposite the second side of the substrate (2) are, wherein the cohesive metallic compound formed in a recess (7) of the substrate (2) as Durchkontaktie- tion by the substrate (2) and the multi-layer contact film (10) within the recess (7) is arranged.

3. Electronic component group (1) according to claim 1 or 2, characterized in that the cohesive metallic connection between the multi-layer contact foil (10) and the contact surface (5) of the electronic component (4) comprises a metallic material (6), preferably silver conductive paste.

4. electronic component group (1) according to claim 1 or 2, characterized in that the multi-layer contact foil (10) also adjacent to the contact surface (5) of the electronic component (4).

5. card-shaped substrate (2) with an antenna (3) arranged thereon with at least one electrical connection surface (8), characterized in that on the connection surface (8) a multi-layer contact film (10) is arranged, the at least a plurality of less than one micrometer thick contiguous layers of mutually exothermically reacting materials is made.

6. card-shaped substrate (2) according to claim 5, characterized in that the multi-layer contact foil (10) is formed coil-shaped and one or more areas with significantly reduced interconnect cross section, wherein the areas with significantly reduced interconnect cross section when exceeding a current threshold value show an exothermic reaction ,

7. Card-shaped substrate (2) according to one of claims 5 or 6, characterized in that the antenna (3) is arranged on one side of the substrate (2), wherein the multilayer contact film (10) in a recess (7) of the substrate ( 2) is arranged as at least part of a through contact to be generated by the substrate (2).

8. Electronic module (4) with at least one electrical contact surface (5) for contacting an electrical connection surface (8) of an antenna (3), characterized in that on the contact surface (5) at least one multilayer contact film (10) is arranged, at least more less than one micron thick contiguous layers of mutually exothermically reacting materials.

9. A method for connecting an electrical connection surface (8) of an antenna (3) arranged on a card-shaped substrate (2) to an electrical contact surface (5) of an electronic component (4) via a cohesive metallic connection, comprising the steps:

Providing the substrate (2) with the antenna (3) and the electronic component (4) arranged thereon,

Arranging at least one multilayer contact film (10) which is made up of at least several layers of mutually exothermically reacting materials which are less than one micrometer thick adjacent to one another, adjacent to the connection surface (8) of the antenna (3) and

- Igniting the multi-layer contact film (10) for forming the coherent metallic compound.

10. The method of claim 9, wherein the antenna is disposed on a first side of the substrate (2), comprising the steps of:

- Producing at least one recess (7) in the substrate (2) from a second side opposite the first side to the antenna

(3)

- Arranging the multi-layer contact foil (10) within the recess (7) and

- Forming the coherent metallic compound in the recess (7) as a via through the substrate (2).

11. The method according to claim 10, characterized in that after arranging the multi-layer contact foil (10) another metallic Material, preferably silver conductive paste, on the second side of the substrate (2) is applied such that it fills the recess (7).

12. The method according to claim 9 or 10, characterized in that the multilayer contact film (10) is arranged such that it also adjoins the contact surface (5) of the electronic component (4).

13. The method according to claim 10 or 11 or claim 12 with 10, characterized in that the ignition by passing an electric current through the multi-layer contact foil (10), by means of a first sliding contact (20b) on the first side of the substrate (2) and a second sliding contact (20a) on the second side of the substrate (2).

14. The method according to claim 13, characterized in that one of the first sliding contact (20b) to the second sliding contact (20a) extending electrical current with respect to the electrical conductivity of the material generated by the multi-layer contact foil (10) cohesive metallic compound is evaluated.

15. The method according to any one of claims 9 to 12, characterized in that the ignition is effected by the action of an electromagnetic field.

16. The method according to claim 15, characterized in that a modulation of the acting electromagnetic field with respect to the electrical conductivity of the multi-layer contact film (10) generated material-conclusive metallic compound is evaluated.