US5202222A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective and precise etching and plating of conductive substrates
Assignee: Shipley Co Inc
•
Filing: 1991-03-01
•
Granted: 1993-04-13
•
Expires: 2011-03-01
Abstract
Abstract Method for selective and precise etching and plating of a conductive substrate through electrophoretic deposition of a photoresist composition. The invention enables chemical milling and plating of products useful in high performance applications such as lead frames with lead widths less than 1.0 mil and precisely plated lead faces.
Inventors
- 👤 Martin J. Harris
- 👤 Ivan K. Ho
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:36
CPC Classifications
H; H10; H10W; H10W70/00; H10W70/01; H10W70/04; H10W70/042; C; C09; C09D; C09D5/00; C09D5/44; C09D5/4407; C09D5/4411; C23; C23F; C23F1/00; C23F1/02; C25; C25D; C25D5/00; C25D5/02; C25D5/022; G; G03; G03F; G03F7/00; G03F7/16; G03F7/164; H05; H05K; H05K3/00; H05K3/0073; H05K3/0079; H05K3/02; H05K3/06; H05K3/061; H05K3/064; H05K3/10; H05K3/20; H05K3/202
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
116 words
A process for plating a lead frame, the lead frame having leads extending from a mounting area on which an integrated circuit or other electronic device can be mounted, the process comprising: (a) electrophoretically applying a photoresist composition on the lead frame; (b) exposing and developing the photoresist whereby the top face of the leads are selectively bared of photoresist; (c) after said exposing and developing of the photoresist, cleaning the top face of the leads that are bared of photoresist to remove essentially all traces of organic substances thereon; and (d) after said cleaning of the top face of the leads that are bared of photoresist, metal plating the bared top face of the leads.
Claim 2
Dependent Claim
116 words
A process for plating a lead frame, the lead frame having leads extending from a mounting area on which an integrated circuit or other electronic device can be mounted, the process comprising: (a) electrophoretically applying a photoresist composition on the lead frame; (b) exposing and developing the photoresist whereby the top face of the leads are selectively bared of photoresist; (c) after said exposing and developing of the photoresist, cleaning the top face of the leads that are bared of photoresist to remove essentially all traces of organic substances thereon; and (d) after said cleaning of the top face of the leads that are bared of photoresist, metal plating the bared top face of the leads.
Claim 3
Dependent Claim
19 words
The process of claim 1 where the photoresist is applied uniformly on the edges and sidewalls of the leads.
Claim 4
Dependent Claim
19 words
The process of claim 1 where the photoresist is applied uniformly on all conductive surfaces of the lead frame.
Claim 5
Dependent Claim
18 words
The process of claim 1 where the top face of the leads are cleaned with a cleaning solution.
Claim 6
Dependent Claim
19 words
The process of claim 4 where the top face of the leads are cleaned with an acidic aqueous solution.
Claim 7
Dependent Claim
19 words
The process of claim 4 where the top face of the leads are cleaned with a neutral aqueous solution.
Claim 8
Dependent Claim
13 words
The process of claim 1 where the photoresist composition is a negative-acting composition.
Claim 9
Dependent Claim
13 words
The process of claim 1 where the photoresist composition is a positive-acting composition.
Claim 10
Dependent Claim
24 words
The process of claim 1 where the photoresist composition comprises a solvent, an organic polymer, an unsaturated monomer, a photoinitiator, an electrolyte and water.
Claim 11
Dependent Claim
30 words
The process of claim 1 where the photoresist composition comprises dimethylamino methacrylate, methyl methacrylate, ethyl acrylate, dipentaerythritol monohydroxy penta-acrylate, propylene glycol methylether, one or more photoinitiators, lactic acid and water.
Claim 12
Dependent Claim
13 words
The process of claim 1 where the photoresist composition comprises a coalescing agent.
Claim 13
Dependent Claim
31 words
The process of claim 11 where the coalescing agent is selected from the group consisting of 1-nitropropane, 2-nitropropane, methyl pyrrolidoine, ethylene glycol ethylhexylether, propylene glycol methylether, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, and mixtures thereof.
Claim 14
Dependent Claim
21 words
The process of claim 1 where the leads of the lead frame have a width of less than about 1.0 mils.
Claim 15
Dependent Claim
22 words
The process of claim 1 where the leads of the lead frame have a width of between about 0.5 and 1.0 mils.
Claim 16
Dependent Claim
19 words
The process of claim 1 where the leads of the lead frame have a width of about 0.5 mils.
Claim 17
Dependent Claim
25 words
The process of claim 1 where the lead frame is vibrated during application of the photoresist whereby gas bubbles adhering to the substrate are dislodged.
Claim 18
Dependent Claim
11 words
The process of claim 1 where the metal is electrolessly plated.
Claim 19
Dependent Claim
11 words
The process of claim 1 where the metal is electrolytically plated.
Claim 20
Dependent Claim
26 words
The process of claim 1 where the metal plated on the conductive surface is selected from the group consisting of gold, silver, palladium, rhodium and ruthenium.
Claim 21
Dependent Claim
25 words
The process of claim 1 where the lead sidewalls are substantially free of the metal plated on the top face of each of the leads.
Claim 22
Dependent Claim
19 words
The process of claim 1 where the lead edges are substantially free of metal plated on the lead edges.
Claim 23
Dependent Claim
23 words
The process of claim 1 where the lead frame can be used for electronic systems operating at frequencies of 10 megahertz or greater.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-04-12 | 1996-10-12 | 1997-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-12 | 2000-10-12 | 2001-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-12 | 2004-10-12 | 2005-04-13 | $7700.00 | Window Closed / Lapsed |