solder spheres which can avoid blackening during transportation have a substantially uniform coating of a lubricant on the surfaces thereof. They are produced by dipping freshly prepared solder spheres in a lubricant solution with a concentration of from 10 ppm to 1000 ppm followed by collection of the spheres and drying. The lubricant is preferably selected from an aliphatic hydrocarbon lubricant, a higher fatty alcohol or acid lubricant, a fatty acid amide lubricant, a metal soap lubricant, a fatty acid ester lubricant, a fluoroplastic lubricant, a silicone lubricant, and a combination thereof.
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3. A method for producing solder spheres coated with a lubricant, which comprises dipping solder spheres in a solution of a lubricant dissolved in an organic solvent with a concentration of from 10 ppm to 1000 ppm, removing the solder spheres from the solution, and volatilizing the solvent remaining on the solder spheres to form a substantially uniform lubricant coating on the surfaces of the solder spheres.
1. solder spheres having a substantially uniform coating of a lubricant on the surfaces thereof.
0. 10. A solder sphere composition comprising lubricant coated solder spheres consisting of solder spheres each having the same diameter and a substantially uniform coating consisting of a lubricant on each of the surfaces of the solder spheres, wherein the lubricant is selected from the group consisting of an aliphatic hydrocarbon lubricant, a higher fatty alcohol lubricant, a higher fatty acid lubricant, a fatty acid amide lubricant, a metal soap lubricant, a fatty acid ester lubricant, a fluoroplastic lubricant, a silicone lubricant, and combinations thereof.
0. 16. A solder sphere composition consisting of a plurality of lubricant coated solder spheres consisting of solder spheres and a substantially uniform coating consisting of a lubricant on the surface of each of the solder spheres, wherein each of the solder spheres has the same diameter and the diameter is sized for placement onto a substrate for use in a ball grid array package, wherein the lubricant is selected from the group consisting of an aliphatic hydrocarbon lubricant, a higher fatty alcohol lubricant, a higher fatty acid lubricant, a fatty acid amide lubricant, a metal soap lubricant, a fatty acid ester lubricant, a fluoroplastic lubricant, a silicone lubricant, and combinations thereof.
2. The solder spheres according to
4. The A method according to
dipping solder spheres in a solution of a lubricant dissolved in an organic solvent with a concentration of from 10 ppm to 1000 ppm,
removing the solder spheres from the solution, and
volatilizing the solvent remaining on the solder spheres to form a substantially uniform coating consisting of a lubricant on the surfaces of the solder spheres, wherein the lubricant is selected from the group consisting of an aliphatic hydrocarbon lubricant, a higher fatty alcohol or acid lubricant, a fatty acid amide lubricant, a metal soap lubricant, a fatty acid ester lubricant, a fluoroplastic lubricant, a silicone lubricant, and a combination thereof.
0. 5. The method according to
6. The method according to
7. A substrate for mounting an electronic component, said substrate having solder bumps formed from the solder spheres according to
8. A process for forming solder bumps on a substrate for mounting an electronic component, which comprises placing the solder spheres according to
9. The process according to
0. 11. The solder sphere composition according to claim 10 wherein the lubricant is stearamide.
0. 12. The solder sphere composition according to claim 10 wherein the diameter is 0.76 mm.
0. 13. The solder sphere composition according to claim 10 wherein the diameter is 0.15 mm.
0. 14. The solder sphere composition according to claim 10 wherein the diameter is 0.1 mm.
0. 15. The solder sphere composition according to claim 10 wherein the plurality of solder spheres are each sized and configured for use on a lead that is on a substrate of an electronic component.
0. 17. The solder sphere composition according to claim 16 wherein the diameter is 0.76 mm.
0. 18. The solder sphere composition according to claim 16 wherein the diameter is 0.15 mm.
0. 19. The solder sphere composition according to claim 16 wherein the diameter is 0.1 mm.
0. 20. The solder sphere composition according to claim 16 wherein the lubricant is stearamide.
0. 21. The solder sphere composition according to claim 16 wherein said substantially uniform lubricant coating is produced by dipping the plurality of the solder spheres in a solution of the lubricant dissolved in an organic solvent with a concentration of from 10 ppm to 1000 ppm, removing the plurality of solder spheres from the solution, and volatilizing the solvent remaining on the plurality of solder spheres to form the substantially uniform lubricant coating on each of the surfaces of the plurality of solder spheres, wherein the lubricant coating is dry.
0. 22. A process for forming solder bumps on a BGA substrate for mounting an electronic component, which comprises placing the solder sphere composition according to claim 11 on a surface of the substrate by using a solder sphere mounter comprising a suction head having suction ports by which the plurality of solder spheres are held and released onto the BGA substrate and heating the substrate to cause the plurality of solder spheres placed thereon to melt and form solder bumps bonded to the substrate.
0. 23. The process according to claim 22 wherein the substrate used for placement of the plurality of solder spheres has a surface coating of a soldering flux in those areas on which the plurality of solder spheres are placed.
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The present invention relates to lubricant-coated solder spheres suitable for use in the formation of solder bumps on a substrate for connecting electronic components to the substrate. The invention also relates to a method for coating solder spheres with a lubricant.
As electronic devices have become increasingly light, thin, short, or compact, electronic components used in these devices have been made compact and multi-functional. In order to produce a multi-functional electronic component, it is necessary to assemble a plurality of amid amide lubricant) dissolved in methylene chloride to give a concentration of 50 ppm, 500 ppm, or 1000 ppm. The solder spheres were collected by centrifugation and dried by volatilizing the solvent in a moisture controlled chamber, leaving solder spheres having a substantially uniform coating of stearamide on the surfaces thereof.
The resulting coated solder spheres and uncoated or bare solder spheres used as controls were subjected to a blackening test, a placement test, and a soldering test in the following manner.
Blackening Test
A 50 cc glass bottle was packed with 40 grams of the solder spheres to be tested. After the bottle was closed with a plastic cap, it was rotated at a rate of 60 rpm using a horizontal spindle holding the bottle in a vertical position until the number of revolutions reached a predetermined value. Thereafter, the lightness of the solder spheres was measured by a spectrocolorimeter. The results are shown in
Placement Test
The solder spheres to be tested which had been subjected to rotation for 10,000 revolutions in the above-described blackening test were placed, using a solder sphere mounter equipped with a suction head having suction ports, on a BGA substrate having flux-coated leads on one surface such that each lead received a solder sphere thereon. The placement of the solder spheres was repeated on ten BGA substrates, and these substrates were observed visually to determine if the solder spheres were placed in good order.
Soldering Test
The BGA substrates on which solder spheres had been placed in the placement test were heated in an infrared reflow furnace to melt and flatten the solder spheres and form solder bumps bonded to the leads of the substrates. The resulting solder bumps were observed visually to determine if their vicinities were clean.
As shown in the accompanying sole FIG. the lubricant-coated solder spheres according to the present invention did not undergo blackening after the container had been rotated for 10,000 revolutions or more in the blackening test. In contrast, in the case of the uncoated solder spheres used as controls, blackening was observed even at 500 revolutions and the degree of blackening reached a saturation point at 5,000 revolutions. The lubricant-coated solder spheres of the present invention in which the lubricant solution used for coating had a concentration of 50 ppm began to undergo blackening at 15,000 revolutions. In this case, the lubricant coating formed on the surfaces of the solder spheres was relatively thin. Therefore, it is estimated that the coating may have been removed or injured during the 15,000 revolutions of rotation and could not completely prevent blackening of the spheres. However, the conditions of the blackening test employed herein were very severe, and solder spheres having resistance to blackening at 10,000 revolutions are considered to be acceptable for practical use.
In the placement test, all the lubricant-coated solder spheres of the present invention could be smoothly transferred from the mounter onto the BGA substrate when they were released from their respective suction ports holding the spheres. In contrast, when the control bare solder spheres were tested, failure of placement was observed in two of the ten BGA substrates used in the test.
In the soldering test, the BGA substrates on which solder bumps had been formed using the lubricant-coated solder spheres of the present invention had a clean appearance in the vicinity of the solder bumps. On the contrary, deposition of black powder was observed on the BGA substrates having solder bumps formed from the control bare solder spheres, particularly in the vicinity of the solder bumps.
It will be appreciated by those skilled in the art that numerous variations and modifications may be made to the invention as described above with respect to specific embodiments without departing from the spirit or scope of the invention as broadly described.
Roppongi, Takahiro, Sohma, Daisuke
| Patent | Priority | Assignee | Title |
| Patent | Priority | Assignee | Title |
| 1797124, | |||
| 1882735, | |||
| 2466695, | |||
| 4298407, | Aug 04 1980 | E. I. du Pont de Nemours and Company | Flux treated solder powder composition |
| 4380518, | Jan 04 1982 | AT & T TECHNOLOGIES, INC , | Method of producing solder spheres |
| 4871110, | Sep 14 1987 | Hitachi, Ltd. | Method and apparatus for aligning solder balls |
| 5447988, | Feb 26 1993 | Loctite Corporation | Solvent free die-attach compositions |
| 5552225, | Mar 16 1994 | Minnesota Mining and Manufacturing Company | Coated grinding aid particle |
| 5784264, | Nov 28 1994 | Godo Kaisha IP Bridge 1 | MCM (Multi Chip Module) carrier with external connection teminals BGA (Ball Grid Array) type matrix array form |
| 5789068, | Jun 29 1995 | SPECIALTY COATING SYSTEMS, INC | Preformed solder parts coated with parylene in a thickness effective to exhibit predetermined interference colors |
| 5872051, | Aug 02 1995 | ULTRATECH, INC | Process for transferring material to semiconductor chip conductive pads using a transfer substrate |
| 5885369, | Aug 15 1996 | Mitsui Mining & Smelting Co., Ltd. | Solder powder, method for making the solder powder and solder paste using the solder powder |
| 6158644, | Apr 30 1998 | ULTRATECH, INC | Method for enhancing fatigue life of ball grid arrays |
| 6165885, | Aug 02 1995 | International Business Machines Corporation | Method of making components with solder balls |
| JP10135618, | |||
| JP10166177, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Mar 31 2000 | SOHMA, DAISUKE | SENJU METAL INDUSTRY CO , LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 035255 | /0140 | |
| Mar 31 2000 | ROPPONGI, TAKAHIRO | SENJU METAL INDUSTRY CO , LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 035255 | /0140 | |
| Nov 01 2010 | Senju Metal Industry Co., Ltd. | (assignment on the face of the patent) | / |
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