Circuit writer materials

• US 5,156,772 A
• Filed: 05/11/1988
• Issued: 10/20/1992
• Est. Priority Date: 05/11/1988
• Status: Expired due to Fees

• Current Assignee: Sophia Systems Co., Ltd. (Kuroda Electric Company Limited)
• Original Assignee: Ariel Electronics, Inc.
• Inventors: Bates, Kenneth N., Neogi, Amar N., Allan, G. Graham
• Primary Examiner(s): Barr, Josephine
• Application Number:
  US07/193,291
• Time in Patent Office: 1,623 Days
• Field of Search: 252/512, 252/514, 524/439, 174/685, 523/457
• US Class Current: 252/514
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 2201/09581 Applying an insulating coating on the walls of holes
• CPC Class Codes: H05K 2201/09827 Tapered, e.g. tapered hole, via or groove bevelled, chamferred or tapered edge H05K2201/09154
• CPC Class Codes: H05K 2201/0989 Coating free areas, e.g. areas other than pads or lands free of solder resist
• CPC Class Codes: H05K 2203/0126 Dispenser, e.g. for solder paste, for supplying conductive paste for screen printing or for filling holes
• CPC Class Codes: H05K 2203/0763 Treating individual holes or single row of holes, e.g. by nozzle
• CPC Class Codes: H05K 3/0091 Apparatus for coating printed circuits using liquid non-metallic coating compositions
• CPC Class Codes: H05K 3/1241 by ink-jet printing or drawing by dispensing
• CPC Class Codes: H05K 3/4069 for via connections in organic insulating substrates
• CPC Class Codes: H05K 3/4644 by building the multilayer layer by layer, i.e. build-up multilayer circuits making via holes in the insulating layers H05K3/0011; special circuit boards as base or core whereon the multilayer is built H05K3/4602

Abstract

Materials are disclosed which are used to produce traces on a circuit board by means of extrusion. The materials are polymer thick films (PTF) which are thixotropic. Conductive traces are composed of conductive particles, a resin and hardener, and two solvents, one having a relatively high volatility and one having a relatively low volatility. Thus when a newly deposited trace is subjected to a stream of hot air, the fast solvent will substantially evaporate leaving a firm paste behind over which another layer of PTF can be written without causing interference between the layers. The slow solvent then permits the various layers of traces to be polymerized together at the same time in a one step operation. The insulative material is similar to the conductive material in that it includes a resin and hardener and two solvents of differening volatility. In addition, in the preferred mode, it includes a gelling agent.

Claims

1. An extrudable polymer thick film material for producing electrically conductive traces on a substrate comprising a mixture of an epoxy resin, a hardener for said epoxy resin, conductive particles, and at least two solvents,

a first one of said solvents being relatively volatile as compared with a second one of said solvents, said solvents being present in quantities and in proportions relative to one another which permit said mixture to be extruded through a nozzle and such that said mixture has a viscosity of between 15,000 and 30,000 centipoise at a static shear rate of 20/sec and a viscosity of from one million to five million centipoise at a shear rate of about 0.01/sec

said conductive particles comprising from 85% to 95% by weight of said mixture, and said resin and hardener comprising 10% to 15% by weight of the mixture.

2. A polymer thick film material mixture as in claim 1, wherein said conductive particles are a mixture of silver flake, silver clusters and silver spheres.

3. A polymer thick film material mixture as in claim 1, wherein said first one of said solvents and said second one of said solvents are present in a proportion of from 2:

1 to 5;

1 by volume.

4. A polymer thick film material as in claim 2 wherein said particles are a mixture of silver flake, silver clusters, and silver spheres in the ration of 96:

24;

5.

5. A polymer thick film material as in claim 1, wherein said first one of said solvents is acetone and the second one of said solvents is N-methylpyrrolidone.