GB2036794A - Solder Preform - Google Patents
Solder Preform Download PDFInfo
- Publication number
- GB2036794A GB2036794A GB7930889A GB7930889A GB2036794A GB 2036794 A GB2036794 A GB 2036794A GB 7930889 A GB7930889 A GB 7930889A GB 7930889 A GB7930889 A GB 7930889A GB 2036794 A GB2036794 A GB 2036794A
- Authority
- GB
- United Kingdom
- Prior art keywords
- solder preform
- tin
- alloy
- solder
- ring
- 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.)
- Withdrawn
Links
- 229910000679 solder Inorganic materials 0.000 title claims abstract description 47
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 22
- 239000000956 alloy Substances 0.000 claims abstract description 22
- 238000007789 sealing Methods 0.000 claims abstract description 21
- 239000004065 semiconductor Substances 0.000 claims abstract description 20
- 238000000576 coating method Methods 0.000 claims abstract description 19
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000011248 coating agent Substances 0.000 claims abstract description 9
- 229910052709 silver Inorganic materials 0.000 claims abstract description 8
- 239000004332 silver Substances 0.000 claims abstract description 8
- 239000012530 fluid Substances 0.000 claims abstract description 4
- 239000008240 homogeneous mixture Substances 0.000 claims abstract description 4
- 229910052718 tin Inorganic materials 0.000 description 10
- 230000004907 flux Effects 0.000 description 7
- 239000006023 eutectic alloy Substances 0.000 description 6
- 238000005476 soldering Methods 0.000 description 6
- JVPLOXQKFGYFMN-UHFFFAOYSA-N gold tin Chemical compound [Sn].[Au] JVPLOXQKFGYFMN-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- QCEUXSAXTBNJGO-UHFFFAOYSA-N [Ag].[Sn] Chemical compound [Ag].[Sn] QCEUXSAXTBNJGO-UHFFFAOYSA-N 0.000 description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 3
- 229910052737 gold Inorganic materials 0.000 description 3
- 239000010931 gold Substances 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 229910000978 Pb alloy Inorganic materials 0.000 description 2
- 229910001128 Sn alloy Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 229910001316 Ag alloy Inorganic materials 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910000464 lead oxide Inorganic materials 0.000 description 1
- YEXPOXQUZXUXJW-UHFFFAOYSA-N oxolead Chemical compound [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000011135 tin Substances 0.000 description 1
- 229910001174 tin-lead alloy Inorganic materials 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- 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
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
- B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering, brazing
- B23K35/0233—Sheets, foils
- B23K35/0238—Sheets, foils layered
-
- 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
- B23K35/262—Sn as the principal constituent
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Ceramic Products (AREA)
- Lead Frames For Integrated Circuits (AREA)
- Coating With Molten Metal (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
- Die Bonding (AREA)
Abstract
A solder preform (14) for hermetically sealing a cover to a container for a semiconductor package comprises a relatively thick flat ring (15) of an alloy consisting of 58 to 68% tin and 32 to 42% lead and having a characteristic that it solidifies from the fluid state as a homogeneous mixture. The solder preform has a relatively thin coating (16, 17) clad on each surface thereof of an oxidation- resistant alloy consisting of 92% to 98% tin and 2% to 8% silver. The thickness of the ring is preferably of the order of 0.0018 inch and the thickness of the alloy coating is preferably of the order of 0.0001 inch. <IMAGE>
Description
SPECIFICATION
A Solder Preform
The present invention relates to a solder preform.
The solder preform of the present invention constitutes an improvement on the solder preform described and claimed in British Patent No.
1391383 dated April 18, 1973, and is useful, inter alia, in the fabrication of an hermetically sealed container for a semiconductor device.
The solder preform of the present invention is of particular utility in hermetically sealing a container for a semiconductor device such as an integrated circuit which must be protected from exposure to ambient atmosphere.
In the manufacture of semiconductor devices, there has been a requirement for hermetically sealing the container in which the active semiconductor device is housed, usually a cavity in a metallic or ceramic body. For this purpose, a metallic cover and a solder preform ring have been used. In accordance with current general practice, the solder preform ring is pre-attached to the sealing cover and the resulting unit disposed over the container of the semiconductor device and heated to fuse the solder preform to the cover and to the container as illustrated and described in the aforesaid British Patent No.
1391383.
In the foregoing method of fabricating hermetically sealed semiconductor packages, it has been customary to use a solder preform formed of an eutectic alloy comprising substantially 80% gold and 20% tin, which has the advantages that it has a desirably high melting point of about 2800C and it has a high tensile strength, ensuring against breaking of the seal due to shocks or rough handling of the semiconductor package. While such solder preforms are eminently satisfactory in use, the recent extreme increase in the price of gold has made them very costly.
The preform solder ring described in British
Patent No. 1391 383 substituted for the gold-tin eutectic alloy a lead-tin-silver alloy coated with a tin-silver oxidation-resistant alloy which compares favourably with the gold-tin eutectic alloy in terms of its relatively high sealing temperature and tensile strength.
However, there have developed requirements for a low-cost solder for semiconductor packages and other applications where a soldering flux cannot be used and which seals at a considerably lower temperature in the range of 2050C to 235 C.
It is an object of the present invention, therefore, to provide a new and improved alloy solder preform for use in hermetically sealing a container for a semiconductor device which has a lower cost, similar to that described in British
Patent No. 1391383, but which fuses and melts at a substantially lower temperature, while retaining or increasing the relatively high tensile strength of the gold-tin eutectic alloy solder preform.
In accordance with the invention, a solder preform comprises a relatively thick flat member of an alloy consisting of 58% to 68% tin and 32% to 42% lead and having the characteristic that is solidifies from the fluid state as a homogeneous mixture and a relatively thin coating on each surface thereof of an oxidation-resistant alloy consisting of 92% to 98% tin and 2% to 8% silver.
The present invention will be further illustrated, by way of example with reference to the accompanying drawings in which:~
Fig. 1 is a perspective view of a portion of a strip of metallic ribbon from which a solder preform of the invention may be punched; while
Fig. 2 is a perspective view of a solder preform embodying the invention.
Referring to Fig. 1, there is illustrated a composite metallic strip 10 comprising a central, relatively thick core 11 of an alloy having the characteristic that it solidifies from the fluid state as a homogeneous mixture, for example an alloy consisting of 58% to 68% tin and 32% to 42% lead, a preferred alloy composition constituting 63% tin and 37% lead. The core 11 has relatively thin coatings 12, 13 on its upper and lower surfaces respectively, these coatings being of an oxidation-resistant alloy, for example, an alloy consisting of 92% to 98% tin and 2% to 8% silver, preferably consisting of substantially 96.5% tin and 3.5% silver. The coatings 12, 13 may be formed on the core 11 by cladding, electroplating, or equivalent process.
From the strip 10 may be punched a series of solder preforms of any desired shape, such as the ring 14 shown in dashed outline in Fig. 1. The resultant punched solder preform ring 14 is shown in Fig. 2 comprising a central, relatively thick flat ring 1 5 and upper and lower coatings 1 6, 1 7 respectively.
As stated, the function of the tin-silver coatings 16, 17 on each surface of the lead core or ring 1 5 is to resist oxidation. Without such a coating, the lead alloy core would oxidize readily and the exposed oxidized surface could inhibit wetting of the solder to the metal cover and to the sealing ring of the semiconductor container. Fluxes to dissolve the oxide cannot be used because such a flux would contaminate the inside of the cavity of the semiconductor container and adversely affect the operation of the semiconductor device in the container.
The ratio of the thickness of the ring 1 5 to that of the coatings 16, 17 is about 18 to 1. In one embodiment of the invention, the thickness of the ring 15 is of the order of 0.0018 inch and that of each of the coatings 1 6, 17 is of the order of 0.0001 inch.
in the hermetic sealing of a cover to a semiconductor container, as the solder preform ring 14 melts, it wets the cover and the surface of the sealing ring of a semiconductor container and alloying of the outer portions of the tin-alloy coatings 1 6, 1 7 with the central core 15 of lead alloy takes place. In addition, the tin-alloy coatings 1 6, 17 alloy with the metal plating, usually gold, silver, or tin, on the cover and the sealing ring of the container.
The tin-lead alloy of ring 15 is a common eutectic alloy solder. However, when used alone as a solder, a flux must be applied to dissolve any lead oxide formed on the surface. The oxidationresistant tin-silver coatings 1 6, 1 7 eliminate such requirement for a soldering flux so that the solder preform can be used for sealing semiconductor packages where the use of a flux is not permitted.
As stated in British Patent No. 1391383, the solder ring described therein has a relatively high sealing temperature of about 27500 so that semiconductor packages utilizing such a solder ring can be sealed at the same temperature profile as the gold-tin eutectic alloy solder which has been the standard of the industry, thus avoiding changes in the apparatus for hermetically sealing containers. However, there are requirements for a low-temperature solder preform for packages such as those using metal covers and metal and plastic preforms and certain other applications in which a flux cannot be used.
The solder ring described above seals over a temperature range of 20500 to 23500, the optimum soldering temperature being of the order of 21600 After completion of the soldering operation, the equilibrium composition of the solder melt of preferred composition is 64.2% tin, 35.6% lead, and 0.2% silver.While, as stated, the sealing temperature of the solder preform is over a range of 20500 to 23500, the actual melting temperature of the alloy ring 1 5 of the preferred composition of 63% tin and 37% lead is about 18300. However, it has been found from production practice that optimum seal yields are achieved when the solder is heated during the sealing process from approximately 2000 to 6000 above the melting point of the solder.
In addition to the lower sealing temperature of the solder preform described above, it has the advantage of substantially higher tensile strength of the order of 7.5x 103 Ibs./sq.in. This minimizes the chances of breakage of the extremely thin solder preform in handling and during assembly of the sealing cover, the solder ring, and the container in the hermetic sealing process.
While the invention has been specifically described as applied to a preform solder ring for hermetically sealing semiconductor packages, it also has other applications in the form of a continuous disc or other flat plate for soldering together other objects; for example, for attaching a semiconductor chip to a package base; soldering a heat sink to a metallized ceramic substrate; attaching a metallized glass member to a metallic supporting member, and other applications.
Claims (8)
1. A solder preform comprising a relatively thick flat member of an alloy consisting of 58% to 68% tin and 32% to 42% lead and having the characteristic that it solidifies from the fluid state as a homogeneous mixture and a relatively thin coating on each surface thereof of an oxidationresistant alloy consisting of 92% to 98% tin and 2% to 8% silver.
2. A solder preform as claimed in claim 1, in which said member is of an alloy consisting of substantially 63% tin and 37% lead.
3. A solder preform as claimed in claim 1 or 2, in which said alloy coating consists of substantially 96.5% tin and 3.5% silver.
4. A solder preform as claimed in claim 1,2 or 3, in which the ratio of the thickness of said member to the thickness of said alloy coating is about 18 to 1.
5. A solder preform as claimed in claim 4, in which the thickness of said member is of the order of 0.0018 inch and the thickness of said alloy coating is of the order of 0.001 inch.
6. A solder preform as claimed in any preceding claim in which said alloy coating is clad on said member.
7. A solder preform as claimed in any preceding claim for hermetically sealing a cover to a container for a semiconductor package in which the flat alloy member is in the form of a sealing ring.
8. A solder preform substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US96436578A | 1978-11-28 | 1978-11-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2036794A true GB2036794A (en) | 1980-07-02 |
Family
ID=25508461
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7930889A Withdrawn GB2036794A (en) | 1978-11-28 | 1979-09-06 | Solder Preform |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5573497A (en) |
| CA (1) | CA1099994A (en) |
| DE (1) | DE2943603C2 (en) |
| FR (1) | FR2442690A1 (en) |
| GB (1) | GB2036794A (en) |
| IT (1) | IT1126816B (en) |
| NL (1) | NL180811C (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2584861A1 (en) * | 1985-07-11 | 1987-01-16 | Nat Semiconductor Corp | METHOD FOR FIXING SEMICONDUCTOR PELLETS AND RESULTING PRODUCT |
| WO1990000954A1 (en) * | 1988-07-19 | 1990-02-08 | Raychem Pontoise S.A. | Solder and connection device incorporating solder |
| WO1990009255A1 (en) * | 1989-02-14 | 1990-08-23 | Raychem Pontoise S.A. | Composite solder article |
| EP0875932A2 (en) * | 1997-04-30 | 1998-11-04 | International Business Machines Corporation | Semi-conductor substrates and methods |
| EP0904887A1 (en) * | 1997-09-29 | 1999-03-31 | TRW Inc. | Gold plated solder material and method of fluxless soldering using said solder |
| GB2387804A (en) * | 2002-04-17 | 2003-10-29 | Agilent Technologies Inc | Component structure |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103157920A (en) * | 2013-04-16 | 2013-06-19 | 昆山市圣翰锡业有限公司 | Novel environment-friendly lead-free low temperature wave tin solder bar |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2362893A (en) * | 1942-04-04 | 1944-11-14 | Metals & Controls Corp | Solder |
| US4020987A (en) * | 1975-09-22 | 1977-05-03 | Norman Hascoe | Solder preform for use in hermetically sealing a container |
-
1979
- 1979-09-06 GB GB7930889A patent/GB2036794A/en not_active Withdrawn
- 1979-09-13 CA CA335,561A patent/CA1099994A/en not_active Expired
- 1979-10-11 NL NLAANVRAGE7907537,A patent/NL180811C/en not_active IP Right Cessation
- 1979-10-17 JP JP13412679A patent/JPS5573497A/en active Pending
- 1979-10-19 IT IT50617/79A patent/IT1126816B/en active
- 1979-10-29 FR FR7926776A patent/FR2442690A1/en active Granted
- 1979-10-29 DE DE2943603A patent/DE2943603C2/en not_active Expired
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2584861A1 (en) * | 1985-07-11 | 1987-01-16 | Nat Semiconductor Corp | METHOD FOR FIXING SEMICONDUCTOR PELLETS AND RESULTING PRODUCT |
| GB2178683A (en) * | 1985-07-11 | 1987-02-18 | Nat Semiconductor Corp | Improved semiconductor die-attach method and product |
| WO1990000954A1 (en) * | 1988-07-19 | 1990-02-08 | Raychem Pontoise S.A. | Solder and connection device incorporating solder |
| WO1990009255A1 (en) * | 1989-02-14 | 1990-08-23 | Raychem Pontoise S.A. | Composite solder article |
| EP0875932A2 (en) * | 1997-04-30 | 1998-11-04 | International Business Machines Corporation | Semi-conductor substrates and methods |
| EP0875932A3 (en) * | 1997-04-30 | 1999-08-04 | International Business Machines Corporation | Semi-conductor substrates and methods |
| EP0904887A1 (en) * | 1997-09-29 | 1999-03-31 | TRW Inc. | Gold plated solder material and method of fluxless soldering using said solder |
| US6203929B1 (en) | 1997-09-29 | 2001-03-20 | Trw Inc. | Gold plated solder material and method of fluxless soldering using solder |
| GB2387804A (en) * | 2002-04-17 | 2003-10-29 | Agilent Technologies Inc | Component structure |
| GB2387804B (en) * | 2002-04-17 | 2005-06-29 | Agilent Technologies Inc | Component structure |
| US6958446B2 (en) | 2002-04-17 | 2005-10-25 | Agilent Technologies, Inc. | Compliant and hermetic solder seal |
Also Published As
| Publication number | Publication date |
|---|---|
| NL180811C (en) | 1987-05-04 |
| FR2442690A1 (en) | 1980-06-27 |
| IT1126816B (en) | 1986-05-21 |
| DE2943603A1 (en) | 1980-05-29 |
| NL7907537A (en) | 1980-05-30 |
| NL180811B (en) | 1986-12-01 |
| CA1099994A (en) | 1981-04-28 |
| DE2943603C2 (en) | 1982-05-19 |
| IT7950617A0 (en) | 1979-10-19 |
| FR2442690B1 (en) | 1984-04-27 |
| JPS5573497A (en) | 1980-06-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |