Edge connectors for printed circuit boards comprising conductive ink

• US 6,265,051 B1
• Filed: 11/20/1998
• Issued: 07/24/2001
• Est. Priority Date: 11/20/1998
• Status: Expired due to Fees

• Current Assignee: 3Com Corporation (HP Inc.)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Jean, Denis
• Primary Examiner(s): LAM, CATHY FONG FONG
• Application Number:
  US09/197,685
• Time in Patent Office: 977 Days
• Field of Search: 252/503, 252/511, 252/514, 439/87, 439/59, 174/257, 174/259, 174/250, 428/209, 428/901
• US Class Current: 428/209
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01B 1/24 the conductive material comprising carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 3/06 the conductive material being removed chemically or electrolytically, e.g. by photo-etch process semi-additive methods H05K3/108
• CPC Class Codes: H05K 3/249 comprising carbon particles as main constituent
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 428/24917 including metal layer
• CPC Class Codes: Y10T 428/31681 Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]

Abstract

Disclosed are edge contacts for printed circuit boards comprising a copper lead coated with conductive ink comprising a binder and graphite powder, carbon black, and silver flakes. Also disclosed are printed circuit boards containing the contacts and methods for manufacturing the contacts and circuit boards.

Claims

1. A printed circuit board comprising at least one edge connector comprising a copper conductor coated with conductive ink comprising a thermoset epoxy binder, graphite powder, carbon black, and silver flakes, wherein the silver flakes have an average size not greater than about 10 μ

m and where the maximum resistance across the edge connector is about 70×

10<sup>−

3</sup>Ω

.

2. A printed circuit board according to claim 1, wherein the edge connector is a PCI bus edge connector.

3. A printed circuit board according to claim 1, wherein the edge connector is an ISA bus edge connector.

4. A printed circuit board according to claim 1, where in the edge connector is an AMR bus edge connector.

5. A printed circuit board according to claim 2, wherein the binder is a cured epoxy resin comprising phenolic monomers.

6. A printed circuit board according to claim 3, wherein the binder is a cured epoxy resin comprising phenolic monomers.

7. A printed circuit board according to claim 1, wherein the conductive ink coated on the edge connector has a sheet resistivity of 0.25 Ω

/square/15 μ

m.

8. A printed circuit board according to claim 7, wherein the edge connector is an ISA bus edge connector.

9. A printed circuit board according to claim 8, wherein the binder is a cured resin comprising phenolic monomers.

10. A printed circuit board according to claim 1, wherein the binder is a cured thermosetting resin.

11. In an edge connector formed by a copper conductor terminating at the edge of a printed circuit board, the improvement comprising applying over the copper conductor a conductive ink comprising silver flakes where the silver flakes are in an amount sufficient to provide a sheet resistivity of from about 0.1 Ω

/sq/15 μ

m to 0.5 Ω

/sq/15 μ

m, the silver flakes having an average grind size not greater than about 10 μ

m.

12. The edge connector of claim 11 wherein the edge connector has a contact resistance of about 50×

10<sup>−

3</sup>Ω

.

13. The edge connector of claim 11 wherein the edge connector has a contact resistance of about 35×

10<sup>−

3</sup>Ω

.

14. The edge connector of claim 11 wherein the edge connector has a contact resistance of about 30×

10<sup>−

3</sup>Ω

.

15. The edge connector of claim 11, wherein the conductive ink comprises thermosetting resin containing graphite powder, carbon black, and silver flakes.

16. The edge connector of claim 11, wherein the silver flakes have an average grind size of about 10 μ

m.

17. The edge connector of claim 11, wherein the amount of silver flakes is from about 50 to 75% by volume of the ink.