US5390080A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tin-zinc solder connection to a printed circuit board of the like
Assignee: Motorola Solutions Inc
•
Filing: 1993-05-03
•
Granted: 1995-02-14
•
Expires: 2013-05-03
Abstract
Abstract An electronic package comprises a component mounted on a substrate, such as a printed circuit board, by a solder connection that is based upon a tin alloy containing zinc. The connection is formed to copper faying surface on the substrate, and includes a first layer formed of a zinc-free tin metal bonded to the copper surface and a second layer formed of the tin-zinc solder alloy bonded to the first layer. The first layer provides a zinc-free barrier between the copper and the tin-zinc alloy to retard zinc migration to the copper interface that would otherwise result in dezincification of the solder alloy and reduce the mechanical properties of the connection.
Inventors
- 👤 Cynthia M. Melton
- 👤 Linda Weitzel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:57
CPC Classifications
B; B23; B23K; B23K35/00; B23K35/001; B23K35/007; B23K35/22; B23K35/24; B23K35/26; B23K35/262; H; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/34; H05K3/341; H05K3/3431; H05K3/3442; H05K3/346; H05K2201/00; H05K2201/10; H05K2201/10613; H05K2201/10621; H05K2201/10636; H05K2201/10954; H05K2201/10992; H05K2203/00; H05K2203/04; H05K2203/043; Y; Y02; Y02P; Y02P70/00; Y02P70/50
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
74 words
An electronic package comprising a substrate comprising a first faying surface formed of copper metal, a component comprising a second faying surface, and a solder connection bonding the first faying surface and the second faying surface, said solder connection comprising a first layer formed of a substantially zinc-free tin-base metal and bonded to the first faying surface and a second layer formed of a tin alloy containing zinc and fused to the first layer.
Claim 2
Dependent Claim
74 words
An electronic package comprising a substrate comprising a first faying surface formed of copper metal, a component comprising a second faying surface, and a solder connection bonding the first faying surface and the second faying surface, said solder connection comprising a first layer formed of a substantially zinc-free tin-base metal and bonded to the first faying surface and a second layer formed of a tin alloy containing zinc and fused to the first layer.
Claim 3
Dependent Claim
20 words
An electronic package in accordance with claim 1 wherein the tin-base metal contains at least about 90 weight percent tin.
Claim 4
Dependent Claim
21 words
An electronic package in accordance with claim 1 wherein the tin alloy contains between about 4 and 12 weight percent zinc.
Claim 5
Dependent Claim
125 words
An electronic package comprising a printed circuit board comprising a bond pad formed of copper metal, an electronic component having a contact formed of a solder-wettable metal, and a solder connection bonding the bond pad and the contact, said solder connection comprising a first layer bonded to the bond pad and formed of a substantially zinc-free solder composed of at least 90 weight percent tin and having first melting temperature, said solder connection comprising a second layer formed of a solder alloy comprising between about 4 and 12 weight percent zinc and the balance substantially tin and having a melting temperature less than the first melting temperature, said second layer being fused to the first layer and bonded to the contact to complete the connection.
Claim 6
Dependent Claim
125 words
An electronic package comprising a printed circuit board comprising a bond pad formed of copper metal, an electronic component having a contact formed of a solder-wettable metal, and a solder connection bonding the bond pad and the contact, said solder connection comprising a first layer bonded to the bond pad and formed of a substantially zinc-free solder composed of at least 90 weight percent tin and having first melting temperature, said solder connection comprising a second layer formed of a solder alloy comprising between about 4 and 12 weight percent zinc and the balance substantially tin and having a melting temperature less than the first melting temperature, said second layer being fused to the first layer and bonded to the contact to complete the connection.
Claim 7
Dependent Claim
28 words
An electronic package in accordance with claim 4 wherein the first melting temperature is at least 220° C. and the second melting temperature is less than 220° C.
Claim 8
Dependent Claim
27 words
An electronic package in accordance with claim 4 wherein the second layer is formed of a solder alloy containing between about 9 and 11 weight percent zinc.
Claim 9
Dependent Claim
21 words
An electronic package in accordance with claim 4 wherein the first layer has a thickness of at least about 25 microns.
Claim 10
Dependent Claim
21 words
An electronic package in accordance with claim 4 where the first layer has a thickness between about 50 and 100 microns.
References Cited (Backward Citations)
JPS63220558A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-02-13 | 1998-08-15 | 1999-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-02-13 | 2002-08-15 | 2003-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-02-13 | 2006-08-15 | 2007-02-14 | $7700.00 | Window Closed / Lapsed |