Conductive adhesive for use in a circuit board

• US 5,432,303 A
• Filed: 08/25/1994
• Issued: 07/11/1995
• Est. Priority Date: 07/19/1991
• Status: Expired due to Fees

• Current Assignee: Poly Circuits, Inc.
• Original Assignee: Poly Circuits, Inc.
• Inventors: Dryer, Joel S., Sexson, Harold L., Turek, Joseph A.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): Thomas, L.
• Application Number:
  US08/296,324
• Time in Patent Office: 320 Days
• Field of Search: 174/259, 174/257, 361/751
• US Class Current: 174/259
• CPC Class Codes: H05K 1/0237 High frequency adaptations H05K1/0216 takes precedence
• CPC Class Codes: H05K 1/034 containing halogen
• CPC Class Codes: H05K 1/05 Insulated conductive substrates, e.g. insulated metal substrate
• CPC Class Codes: H05K 2201/015 Fluoropolymer, e.g. polytetrafluoroethylene [PTFE]
• CPC Class Codes: H05K 3/0061 onto a metallic substrate, e.g. a heat sink heat sinks for electric apparatus H05K7/20
• CPC Class Codes: H05K 3/321 by conductive adhesives
• CPC Class Codes: H05K 3/386 by the use of an organic polymeric bonding layer, e.g. adhesive
• CPC Class Codes: H05K 3/42 Plated through-holes or plated via connections
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49144 by metal fusion
• CPC Class Codes: Y10T 29/49165 by forming conductive walled aperture in base

Abstract

A double-sided printed circuit board and a method for making the circuit board. The circuit board includes a metal support that functions as both a heat sink and a ground plane. The circuit board contains a dielectric having first and second conductive foil platings on opposing sides of the dielectric. Prior to bonding the first foil plating to the metal support with a conductive adhesive, a standard protective coating on the first foil plating, which typically remains on the foil plating in conventional practice, is removed in order to expose a bare surface of the first foil plating. The exposed bare surface of the first foil plating is then bonded to the metal support before any substantial oxidation or a build up of impurities on the first foil plating surface can occur.

Claims

1. An electrically conductive adhesive, comprising in combination:

(a) a silicone polymer selected from the group consisting of a phenyl-based silicone polymer and a vinyl-based polysiloxane elastomeric polymer and mixtures thereof;

(b) a polysiloxane coupling agent;

(c) a heat stabilizer;

(d) an anti-oxidizer;

(e) a peroxide catalyst;

(f) an adhesive promotor comprising an organofunctional silane and a zirconate coupling agent; and

(g) a conductive filler selected from the group consisting of silver, silver graphite and silver aluminum.

2. The combination of an electrically conductive adhesive as in claim 1, wherein the adhesive is used as a bonding layer between a two-sided circuit board and a metal support, the adhesive being formed in a layer having a pattern conforming to a foil pattern of one of the sides of the circuit board.

3. The combination as set forth in claim 2 in which the adhesive, after being formed into a sheet and pattern to conform to the foil pattern of said circuit board, is interposed between the circuit board and the metal support for forming a conductive bond therebetween.