Patent US4589962A successfully refreshed from Google Patents.
US4589962A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solder plating process and semiconductor product
Assignee: National Semiconductor Corp
•
Filing: 1985-06-03
•
Granted: 1986-05-20
•
Expires: 2005-06-03
Abstract
Abstract A method for solder plating metal leads in plastic semiconductor packages comprises cleaning the leads followed by electroplating tin or a tin/lead alloy onto the leads. The cleaning is effected with a non-corrosive solution which is either a carboxylic acid, a hydroxycarboxylic acid, or a combination of both. The electroplating solution is a sulfonic acid or citric acid based system, including suitable tin salts and/or lead salts. A sequestering agent may be used to inhibit the corrosive effect of the electroplating bath.
Inventors
- 👤 Vijay M. Sajja
- 👤 Ranjan Mathew
- 👤 Jagdish Belane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 03:32
CPC Classifications
C; C25; C25D; C25D3/00; C25D3/02; C25D3/56; C25D3/60; C25D3/30; C25D3/32; C25D5/00; C25D5/34; H; H10; H10W; H10W70/00; H10W70/01; H10W70/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
69 words
A method for solder plating metal leads on a plastic semiconductor package, said method comprising: exposing the plastic semiconductor package to an organic acid selected from carboxylic acids and hydroxycarboxylic acids to remove metal oxide from the leads; and electroplating tin or a tin/lead alloy onto the metal leads in a non-corrosive electrolyte wherein tin salts or tin and lead salts are present in sulfonic acid or citric acid.
Claim 2
Independent Claim
69 words
A method for solder plating metal leads on a plastic semiconductor package, said method comprising: exposing the plastic semiconductor package to an organic acid selected from carboxylic acids and hydroxycarboxylic acids to remove metal oxide from the leads; and electroplating tin or a tin/lead alloy onto the metal leads in a non-corrosive electrolyte wherein tin salts or tin and lead salts are present in sulfonic acid or citric acid.
Claim 3
Dependent Claim
26 words
A method as in claim 1, wherein the carboxylic acids are selected from the group consisting of oxalic acid, malonic acid, succinic acid, and glutaric acid.
Claim 4
Dependent Claim
26 words
A method as in claim 1, wherein the hydroxycarboxylic acids are selected from the group consisting of citric acid, ascorbic acid, malic acid, and lactic acid.
Claim 5
Dependent Claim
15 words
A method as in claim 1, wherein the organic acid is at an elevated temperature.
Claim 6
Dependent Claim
18 words
A method as in claim 1, wherein the electrolyte is sulfonic acid based and includes a sequestering agent.
Claim 7
Dependent Claim
23 words
A method as in claim 1, wherein the electrolyte is citric acid based with a pH in the range from 6 to 7.
Claim 8
Dependent Claim
33 words
A method as in claim 1, wherein the plating bath includes tin alkane sulfonate salt or a tin alkane sulfonate salt and a lead alkane sulfonate salt in a sulfonic acid based electrolyte.
Claim 9
Dependent Claim
29 words
A method as in claim 1, wherein the electrolyte includes a tin citrate salt or a tin citrate salt and lead citrate salt in a citric acid based electrolyte.
Claim 10
Dependent Claim
10 words
Semiconductor packages produced according to the method of claim 1.
References Cited (Backward Citations)
US3427232A
Cited
US4163700A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-19 | 1989-11-18 | 1990-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-19 | 1993-11-18 | 1994-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-19 | 1997-11-18 | 1998-05-20 | $7700.00 | Window Closed / Lapsed |