CA1122856A - Process for in-situ modification of solder composition - Google Patents

Process for in-situ modification of solder composition

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Publication number
CA1122856A
CA1122856A CA332,645A CA332645A CA1122856A CA 1122856 A CA1122856 A CA 1122856A CA 332645 A CA332645 A CA 332645A CA 1122856 A CA1122856 A CA 1122856A
Authority
CA
Canada
Prior art keywords
solder
indium
wetting agents
molten
flux
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
Application number
CA332,645A
Other languages
French (fr)
Inventor
Nicholas G. Koopman
Vincent C. Marcotte
Stephen Teed
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Business Machines Corp
Original Assignee
International Business Machines Corp
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Filing date
Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Application granted granted Critical
Publication of CA1122856A publication Critical patent/CA1122856A/en
Expired legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/10—Bump connectors ; Manufacturing methods related thereto
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
    • B23K35/268—Pb as the principal constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
    • B23K35/3612—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with organic compounds as principal constituents
    • B23K35/3618—Carboxylic acids or salts
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    • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
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    • H05K3/3489—Composition of fluxes; Methods of application thereof; Other methods of activating the contact surfaces

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  • Engineering & Computer Science (AREA)
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  • Power Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electric Connection Of Electric Components To Printed Circuits (AREA)
  • Wire Bonding (AREA)

Abstract

PROCESS FOR IN-SITU MODIFICATION OF SOLDER COMPOSITION

Abstract Extraction of non-lead components (e.g. tin, indium, etc.) from solder joints with monocarboxylic acids of alkylated hydrophenanthrene nuclei to increase the lead content of the solder joints.

Description

PROCESS FOR IN-SIT~ MODIFICATION OF SOLDER COMPOSITION
Description Technical Field This invention relates to soldering techniques and, S more particularly, to a method for maximizing the lead content of solder joints, inclusive of the type -employed in semiconductor fabrication.
. :. .
One object of the present invention is to provide a ; novel method for obtaining improved solder joints.
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` 10 Another object of the present invention is to provide ; a novel method for increasing the fatigue li~e of lead based solder joints, by modifying the solder composition, after joining, to a more fatigue ~ resistant alloy.
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A further object of this invention is to provide a novel method for increasing the creep resistance of lead based solder joints, by modifying the ~ composition, after joining, to a more creep ; resistant alloy.
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A still further objéct of this invention is to provide a novel method for maximizing the lead content of lead based solder joints.

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1 Another object of this invention is to provide means for altering the composition of molten solder joints to iso-thermally shift the melting point of the solder into the solidus portion of its phase diagram.

Another object of the present invention is to provide lm-proved solder interconnections between a semi-conductor device and an underlying conductive pattern of a support-ing carrier.
Our invention provides a method of altering the composition of solder alloys containing wetting agents selected from the group o~ tin and indium when the solder alloy is in-situ. The solder alloy, in its molten state, is fluxed with at least one acid selected from the monocarboxylic acids of alkylated hydrophenanthrene nuclei having the empirical formula ClgH29COOH for sufficient time to materially reduce the the content of the wetting agents in the molten solder by leaching them from the solder.
Background Art ; It is known that pure lead (Pb) is not employed for solder connections since it does not provide the wettability required for good solder joints such as can be obtained with lead alloys such as 95/5-PbSn and 95/5-PbIn solders.

However, pure lead or lead with very high lead content solder joints would provide fatigue lives of better than 2X to 3X, as compared to conventional lead alloy solders.
Also, substantially pure lead solder joints would provide increased creep resistance under sustained loads, as compared to 50/50 PbIn solder. See for example~ U.S.
Patent No. 3,380,821, and the R. Herdzik et al article "Dummy Pads for Increased Creep Resistance", p. 1394, of the IBM* Technical Disclosure Bulletin, Vol. 20, No. 4, September 1977. To date, no satisfactory way has been known to obtain lead solder joints without inclusion of substantial amounts of wetting agents such as tin or indium.
*Registered Trade Mark of International Business Machines Corporation --2~

Brief Description of the Drawings IG. 1 is an exaggerated cross-section of a structure obtained in the formation of a solder pad.

FIGS. lA and lB are scanning electron microscope photos at 700X at a 60 angle of, respectively, the structure of FIG. 1 and a solder pad subjected to leaching of wetting agents in accordance with this invention.

FIG. 2 is an equilibrium Pb-In binary phase diagram.

FIG. 3 is a time dependence curve for the leaching of indium from a 50/50 InPb solder pad.

FIG. 4 is a graph showing the effect of time at temperature on indium leaching from a 50/50 InPb solder pad.
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jFIG. 5 is a thermal profile of a furnace set to 280C. ~-FIGS. 6A and 6B illustrate stages in the maximiza tion of lead in solder joints as applied to semi-eonduetor fabrication.

-Disclosure of the Invention It has been found that lead content in lead alloy solder joints can be maximized, partieularly in flip-chip bonding (see above referred to IBM-TDB) of semieonduetor deviees to substrates by composi-25 ~ional modifieation of eonventional lead alloy solder ~

: ~, ~, .
.

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, B~6 joints, after formation. Formation of such solder - joints would include the initial use of conventior.a solders, such a~ 95/5 PbSn (lead tin) and 95/5 PbIn or 50/50 PbIn (lead indium) solders, and leaching excess tin or indium, from the resulting joints, with a flux comprised of at least one resin acid selected from monocarboxylic acids of an alkylated hydrophenanthrene nuclei having the empirical formuLa ClgH20COOH. In this manner, the flux, at elevated temperatures will lower the tin conte~t of a 95/5 PbSn solder joint to less than 1 wt~.
Indium reacts even faster and can be leached out of a PbIn solder ~oint much easier.

Best Modes for Carrying Out The Invention The majority of the experiments described herein employed integrated circuit chips lj hereinafter referred to as device chip (FIG. 1) inclusive of a first level aluminum metallization 2, a silicon oxide (SiO2) layer 3, and a contact pad 4 comprised 210 of a 2000A chrome (Cr) layer 5, a lO,OOOA layer 6 o copper (Cu) initially phased with Cr (e.g. a 8100A
layer 7) and 1400A gold (Au) layer 8. See as an ex-ample Fig. 1 of the C. Johnson et al. article "Removal Technique", pp. 2209-10 of the IBM TDB, Vol. 20, No. 6, November 1977. Each integrated circuit chip contained 121 of such contact pads 4.

Wafers containing such device chips will hereinafter be referred to as device wafers, each containing several hundred device chips. The solder pad 9 was evaporated on the contact pads 4 through a mask to a height of 4.5 mils. Because of the higher vapor pressure of Pb, it was deposited first in a layer 10 followed by deposition of indium (In) in a layer 11. The shape of the evaporated solder pads .~ ' .

` ~
, , was that of a truncated cone. The term "wetback"
as is used herein denotes a reflow operation for modification of the solder pads, as for example to coalesce the two layer solder pad 4 so as to amalgamate the wetting agent, indium or tin layer 11 into the lead as a solder alloy.

Compositions of solder alloys, including all solder pads, were determined by measuring their melting points using a Perkin-Elmer ~SC-II unit (e.g. by Differential Scanning Calorimetry). ~ecause of ex-perimental ease, the cooling traces were used in the measurements. Standards of known compositions were also prepared and run under the same conditions as the solder alloys and the solder pads, including the same amount of material.

The majority of the experiments were conducted in a tube furnace with a nitrogen atmosphere. The samples were placed in a beaker covered with a leach-ling flux and placed in the furnace on a glass plate with a thermocouple attached.

The fluxes used were Alpha Metals a-102-1500 (with addition of 20~ isopropyl alcohol, e.g. IP~, based ~` on the weight of a-102-1500) and a-100~40. Also used were water white rosin and a water soluble flux TBC comprised of 50 vol% triethanolamine and `` 50 vol% butyl cellosolve. The ~-102-1500 flux will be hereinafter referred to as a-102 with the second numerical portion (e.g. 1500) designating the viscosity of the flux. Similarly, the a-100-40 flux will be designated hereinafter as a-104.

8S&i The ~-102 flux is supplied as 68~ solution of abietic acid in benzyl alcohol, and the ~-104 flux as a 40~ solution of abietic acid in isoproponal.
Water white rosin is a resin acid of a monocarboxylic acid of alkylated hydrophenone nuclei having the empirical formula ClgH29COOH.

The first experiments employed two device wafers (containing 200 device chips) which had complete processing through sequential deposition of 50/50 InPb solder mounds 9, e~g. Pb layer 10 and indium layer 11 (see FIGS. 1 and lA). To half of one wafer, the ~-102 was applied about the solder mounds which were reflowed at 275C for two minutes, called herein "leach reflow". After the leach re-flow, part of this wafer half was subjected to asecond "reflow fix" treatment in a nitrogen (N2) ambient at 275C for two minutes. The remaining portion of the half wafer was subjected to both re-flow treatments in the reverse order, e.g. first a reflow fix at 275C for two minutes in a nitrogen ; atmosphere, followed by a leach reflow with ~-'102 at 275C for two minutes.

The results are shown in Table 1 below which show that the reflow fix in N2 has no effect on the indium concentration whereas the indium concentration wac reduced by the leach reflow with -102.

; .

, ~ .

.

Table 1 Study of the relative effects of the reflow process with N2 and ~-102 flux on In content of solder pads.
Wafers with nominal 50 InPb through regular wetback furnace.

PROCFSSING In CONCENTRATION*
Sample 1 As evaporated 46%
Flux Reflow 39 Flux ~ N2 Reflow 40-~

Sample 2 As evaporated 46% -N2 Reflow 44 N2 ~ Flux Reflow 40~

* Determined from melting points by DSC.

The next experiment employed individual segments of the wafer containing three device chips each Gsub-divided from the device wafer) placed in a beaker and covered with various fluxes for set times and temperature. In additionj a control sample was em-ployed in which the solder mound was only reflow fixed in nitrogen. In each case, the samples had a contact pad 4. Also employed were samples in which a solder mound 9 was evaporated directly on blank silicon substrates. Table 2 below shows the effect of leaching indium by different fluxes at 280C
for one-half hour.
.
This invention also enables the rework or replace-ment of one or more chips of a plurality there ' `. .

::

bonded to a carrier (e.g. a multi-level ceramic substrate) by, for example, a high melting point solder s~ch as a 85% Pb/l5s~ In solder (see FIG. 2).
In such application, due to minuteness of the solder joints, a chip may be mechanically torn or separated from the carrier, followed by position-ing a new chip at the stripped site, with chip provided with low melting point solder, e.~.
55% Pb/45~ In, and heating the unit to a temperature (e.g. 250C, see FIG. 2) above the melting point of 55Pb/45In solder but below the ; melting point of the 85~ Pb/15~ In, while fluxing, in accordance with the foregoing, to isothermally alter the composition of the 55Pb/45In to 85Pb/
15In, which conversely places the solder in solidus portion of the phase diagram. In this manner, chips can be replaced from a multi-chip array with-out need to melt the sol~er joints of the remaining chips.
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~s seen in Table 2, the control sample did not change with heating and was the same composition as a non-heat treated the same. All the rosin based fluxes (e.g. a-102, a-104 and abietic acid) induced a large reduction in the indium content.
The water soluble TBC induced only a slight de-crease in the indium content of the solder mounds.
Chips without contact pads had a higher indium content reflecting the lack of influence of the copper and gold metallurgy. The indium content as determined by weight loss showed slight variability, which is attributed to poor cleaning of the samples after leach reflow.

In FIGS. lA and 1~ are shown SEM ~scanning electron microscope) micrographs of two solder pads; one as evaporated and the other after a half hour leach reflow at 280C in a-102 flux. The indium cap 11 can be seen on the as-evaporated solder pad, as well as the cllange in volume of the solder pad due 20, to heating in the flux which reflects the loss of indium from the solder pad. ' The temperature dependence of the leaching of . indium from 50/50 InPb solder mounds is shown in Table 3 below.

.

, . ~ . .

ll Table 3 Effect of Temperature on Leaching of In from 50/50 InPb Solder Mounds. ~-102-1500 t 20% IP~ (isopropyl alcohol) ~lux for 1/2 hour at 'l`emperature.

S In Content Temp C Weight Loss Wei.gllt Loss DSC
mg . ~
280C 1.6 8% ~%

250C 1.1 25% 15%

10l 225C 0~24 42% 42%

200C 0.1 45% 45%
.
In Table 3, all chips were held for a half hour at i the indicated temperatures. The same results are plotted on a Pb-In phase diagram in FIG. 2j which shows graphically the reduction of indium at 280C
and 250C.

The time dependence of a 102 and TBC reactions were determined at 280C on 50/50 InPb solder mounds.
The a-102 flux was reacted at 280C with the chip samples as-evaporated and after a prior reflow fix treatment, no difference was noted between the two as shown in Tab1e . below.

' , ~

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. ` ~ i ~ . .. .;
. . ~ .
: "

' ' .. , , . . , ~ ~ . . .

Table 4 Effect of Time at 280C on I,eachiny of In From 50/50 InPb Soldcr Pads.

O In Remaining in Pads (by DSC) Time in TBC ~-102~1500 + 20% IPA With Prior Furnace As-Eva~ p N~ Reflow Set 0 Min. 46 46 46 5 Min. 46 44 44 10 Min. 45 27 29 15 Min. 43 15 15 ' 30 Min. 38 8 8 - .
at 350C 5 Min. ~-102 7% In Remaining A plot of the time dependence of the ~-102 and TBC
fluxes is shown in FIG. 3. There is an "incubation time" for the ~-102 flux, then a very rapid leach-ing action with the rate slowing down as the indium concentration decreases. The TBC flux had a constant rate of decrease.

In FIG. 4 is shown the time dependence of the ~102 flux at different temperatures, with the 250C
curve probably having the SaMe shape as the 280C
curve, if additional points were established. It may be noted that after 5 n;inutes at 350C, the indium content is essentially the same as that after a half hour at 280C.
.

.. . .

f~S~

The time in all of the foregolng experiments ~as the total time in the furnace. In FIG. 5 is shown the urnace thermal profile set to 280C, which was obtained by placing the thermocouple in a beaker of flux and monitoring the temperature with the beaker placed in the furnace. All conditions were similar to the experimental conditions. After five minutes, the temperature is only 245C, which appears to explain the "incubation time" indicated in FIGS. 3 and 4.

A check on the approxima~e solubility of indium in abietic acid was done by holding 500mg slugs of pure indium in known weights of abietic acid. The results for 200C and 280C are given in Table 5 below.

Table 5 Solubility* of Pure In in Abietic Acid After Leaching (By Weight Loss) Solubility 200C 44 Hr. 5.1 - 6.8~ In .
280C 19 Hr. 6 - 10~ In * Not necessarily Equilibrium Indium and Abietic Acid Analy~ed by DSC and DTA
(differential thermal analysis) Results Inconclusive.

For this Table, the weight loss of the indium was determined and solubilities calculated. Two solubility values are given based on initial and final weight of the rosin, since there is loss of abietic acid on heating. The difference in solu-bility betveen 200C and 280C is not great enough .~ ' ' ' "' s~
1~
to e~plain -the results of -the lcaching experiments given in Table 3 and shown in FIG. 2.

Since the solubility of indium in rosin is in the order of 10~ at 280C, the reduction of rosin in the flux would reduce the amount of indium removed. The effects of the variation in weight ratio of rosin to 50/50 InPb was studied at 280C (actual temperature of sample was 285C). Two ratios of rosin to 50/50 InPb were used 1:1 and 5:1. A 200my piece of 50/50 InPb was placed in a beaker with the required weight of rosin. The results are shown in Table 6.

Table 6 _ ~ .. _ Indium Dissolution-Bulk Studies As Function of Rosin: Alloy 50 InPb Ratio Ratio1:1 5:1 200:1*
% In Left % In Left % In Left TimeWeight Loss DSC Weight Loss DSC DSC
1/2 Hr. ~ 8 1 Hr. 47 47 42 42 :`
4 Hrs. 49 47 29 34 .~ .
12 Urs,. - - 27 26 15 Ilrs. 45 46 - - -* From Results on Chip Pads .. ~ ... .. .

As would be expected, the more rosin the greater the reduction of indium in the alloy. For comparison, the results on chlp solder mounds are shown utlllz-ing contact pads. The nominal ratio of rosin to 50/50 InPb was 200:1 which may have varied by ~ 25o .
With the greater slnk of rosin present with the chips, a much greater depletion of lndium occurred in a much shorter time.

Another way to present these results is to look at the concentration of lndium in the rosin. These results are shown in Table 7.

Table 7 Indium Dissolution-Bulk Studies As Function of Rosin: 50 InPb Ratio, Indium Concentration ln Rosin 15 , (By Weight Loss) ; 285C
Ratio 1:1 5:1 200:1*
% Indium% Indium ~ Indium , in Rosinin Rosin in Rosin 20 Time Final Final 1/2 Hr. 0.2 1 Hr. 7.3 3,4 ; ~ ' ' ' ' 4 Hrs. 4.0 7.2 12 Hrs. 7.8 15 Hrs. 13.2 * From Results on Chip Pads .~ ~

~, - .

5~

The results are given as compositions using inal weights of rosin. The rosin was most likely saturated with indium or nearly so after 15 hours for the 1:1 weight ratio. For the 5:1 ratio after 12 hours, the rosin was not saturated and for the chips very little indium was in solution, althouyh nearly all the indium was removed from the solder pads. This clearly shows that the greater the weight ratio of rosin to 50/50 InPb alloy the greater the dissolution, which should be expected.

A chip with 5/95 SnPb was held at 350C for a half hour and the Sn content was reduced from 5~ to 3/4 Sn with ~-102 flux. The results given in Table 8 along with atomic absorption (AA) show results for shorter heat-treatment times.

Table 8 Sn Dissolution by ~-102-1500 at 350C for 2 minutes Multiple Wetback Excess Flux 20 SampleSn Content DSC AA*
Control - Cleaned 4.6% 7.1 1 Wetback + flux 3.1% 5.2
-2 Wetback ~ new flux 2.3% 2.7 * Results questionable since technique is not sensitive to tin. -.

.

5~

Although there i5 a discrepancy in the higher Sn content alloys, it is demonstrated that Sn is also leached fro~l SnPb solders by rosin base fluxes.
Chips with llominal 5/95 SnPb were sent through three reflow cycles using ~-102-1500 + 20% IPA with new flux each time. The composition changed from 4.5 Sn to 3.5% Sn as measured by DSC.

FIGS. 6A and 6s illustrate stages in the fabrication of modified chip solder joining of a chip 20 to a ,conductor pattern 21 of a ceramic carrier 22.
Although not shown, the device chip 20 incorporates an integrated circuit provided with a first level aluminum conductor pattern 23, portions of which are ,exposed by contact opening in a passivating layer 24 such as silicon dioxide. Contact pads 4 (e.g. such as in FIG. 1) are formed about each opening in contact with the lower aluminum metallization 23.
Sequentially deposited on each contact pad is the lead layer 10 and the tin layer llA as a bilayered Isolder mound 9. This bilayered solder mound 9 can be reflowed to amalgamate the tin layer llA into the lead layer 10 to form a 5/95 SnPb alloy solder mound 25. The chip 20 is then superimposed on the ,~
`~ ceramic substrate 22 with alloy solder mounds 25 in 25 register with required metallization 21 of the ' ceramic substrate 22, and the units joined by con-ventionql solder reflow operation. The voids between the joined chip 20 and substrate 22 are filled with ~-102 flux fill 30 and the assembly ~0 reflow leached at for 1/2 hour at 350~. The tin content of the alloy solder mounds 25 was reduced to about 0.~ tin.

.

. . .
: .
~ ' , .

. . .

35~

While the invention has been illustrated and des-cribed with reference to preferred embodiments thereof, it is to be unders-tood that the inve~tion is not limited to the precise construction herein disclosed and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.

Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A method for in-situ altering the composition of solder alloys containing wetting agents selected from the group of tin and indium comprising fluxing a said solder alloy in its molten form for sufficient time with at least one acid selected from the monocarboxylic acids of alkylated hydrophenanthrene nuclei having the empirical formula C19H29COOH to materially reduce the content of said wetting agents in said molten solder.
2. The method of Claim 1 wherein said acids are in the form of water white rosin.
3. The method for in-situ altering the composition of solder alloys containing wetting agents selected from the group of tin and indium comprising:
applying said solder alloy between solderable parts, to be joined together, at a temperature above the melt-ing point of said solder alloy, and fluxing said solder alloy in molten form for a time sufficient to materially reduce the content of said wetting agents in said molten solder.
4. The method of claim 3 wherein said solder is fluxed for a time at said temperature to remove sufficient amount of said wetting agents to shift the composition of said molten solder at said temperature to a point on the solidus curve of the phase diagram of said solder alloy.
5. The method of Claims 1, 2 or 3 wherein solder alloys join a semiconductor device to a supporting dielectric substrate wherein the circuit configuration of said device is electrically interconnected to a circuit pattern of said substrate.
CA332,645A 1978-09-20 1979-07-27 Process for in-situ modification of solder composition Expired CA1122856A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US94422478A 1978-09-20 1978-09-20
US944,224 1978-09-20

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5007163A (en) * 1990-04-18 1991-04-16 International Business Machines Corporation Non-destructure method of performing electrical burn-in testing of semiconductor chips

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4498096A (en) * 1981-01-30 1985-02-05 Motorola, Inc. Button rectifier package for non-planar die
EP0068091B1 (en) * 1981-06-30 1988-08-10 International Business Machines Corporation Method for connecting a semiconductor chip to a substrate and such connection
JPS5839047A (en) * 1981-09-02 1983-03-07 Hitachi Ltd Semiconductor device and manufacture thereof
US4896817A (en) * 1988-10-17 1990-01-30 International Business Machines Corp. Flux composition and method of decreasing tin content in lead/tin solder joints
CN105759522B (en) * 2016-05-11 2019-01-22 深圳市华星光电技术有限公司 The broken wire repair method of TFT substrate

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US2043573A (en) * 1934-05-26 1936-06-09 American Smelting Refining Process for recovering tin
US3380821A (en) * 1965-10-21 1968-04-30 Gen Motors Corp Heat treatable creep resistant solder alloy
US3478414A (en) * 1967-05-05 1969-11-18 Ibm Water white rosin flux in benzyl alcohol solution

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5007163A (en) * 1990-04-18 1991-04-16 International Business Machines Corporation Non-destructure method of performing electrical burn-in testing of semiconductor chips

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