Abstract An assembly comprising a PTC heater, a body to be heated thereby, and a bonding layer interposed therebetween. The heater is formed from a ceramic type PTC electrical resistance material which will generate heat in response to the flow of electric current therethrough. It has a surface portion through which heat is to be transferred and through which electrical current will flow. The body to be heated has a thermally and electrically conductive surface portion of a shape which substantially matches that of the heater surface portion. The body has a thermal coefficient of expansion differing from that of the heater resistance material. The layer of bonding material is electrically and thermally conductive and is interposed between these surface portions for the transfer of heat and conduction of electric current therethrough. It comprises a mixture of small electrically and thermally conductive particles dispersed throughout a flexible, elastic and creep-resistant high temperature resin material stable at temperatures on the order of at least 150*C. and free of components which tend to degrade the PTC material.
AN ASSEMBLY COMPRISING: A HEATER FORMED FROM A CERAMIC TITANATE PTC ELECTRICAL RESISTANCE MATERIAL WHICH WILL GENERATE HEAT IN RESPONSE TO THE FLOW OF ELECTRIC CURRENT THERETHROUGH, SAID HEATER HAVING A SURFACE PORTION THROUGGH WHICH HEAT IS TO BE TRANSFERRED AND THROUGH WHICH ELECTRICAL CURRENT WILL FLOW, A METAL BODY WHICH IS TO BE HEATED AND WHICH HAS A THERMALLY AND ELECTRICALLY CONDUCTIVE SURFACE PORTION SUBSTANTIALLY MATCHING IN SHAPE WITH THAT OF THE HEATER SURFACE PORTION AND TO WHICH HEAT IS TO BE TRANSFERRED FROM SAID HEATER, SAID BODY HAVING A THERMAL COEFFICIENT OF EXPANSION DIFFERING FROM THAT OF THE HEATER RESISTANCE MATERIAL, AND A LAYER OF ELECTRICALLY AND THERMALLY CONDUCTIVE MATERIAL INTERPOSED BETWEEN SAID SURFACE PORTIONS FOR SECURING SAID HEATER AND BODY TO EACH OTHER AND FOR THE TRANSFER OF HEAT AND CONDUCTION OF ELECTRIC CURRENT THERETHROUGH BETWEEN SAID HEATER AND BODY, SAID LAYER COMPRISING A MIXTURE OF SMALL ELECTRICALLY AND THERMALLY CONDUCTIVE PARTICLES SELECTED FROM THE GROUP OF SILVER, SILVER-COPPER ALLOYS AND GRAPHITE MATERIALS DISPERSED THROUGHOUT A MATERIAL SELECTED FROM THE GROUP CONSISTING OF SILICONE RESIN, POLYIMIDE RESIN, BENZOPHENONE RESIN, POLYAMIDE-IMEDE RESINS, POLYBENZIMIDAZOLE RESINS, POLYBENZOTHIAZOLE RESINS, POLYETHYLENEIMINE RESINS, PHOSPHONITRILIC RESINS AND POLYESTER RESINS SO THAT SAID LAYER IS FLEXIBLE, ELASTIC AND CREEP-RESIS TANT AND STABLE AT TEMPERATURES ON THE ORDER OF AT LEAST 150*C. AND FREE OF COMPONENTS WHICH TEND TO DEGRADE THE PTC HEATER MATERIAL.
Claim 2
Dependent Claim
228 words
AN ASSEMBLY COMPRISING: A HEATER FORMED FROM A CERAMIC TITANATE PTC ELECTRICAL RESISTANCE MATERIAL WHICH WILL GENERATE HEAT IN RESPONSE TO THE FLOW OF ELECTRIC CURRENT THERETHROUGH, SAID HEATER HAVING A SURFACE PORTION THROUGGH WHICH HEAT IS TO BE TRANSFERRED AND THROUGH WHICH ELECTRICAL CURRENT WILL FLOW, A METAL BODY WHICH IS TO BE HEATED AND WHICH HAS A THERMALLY AND ELECTRICALLY CONDUCTIVE SURFACE PORTION SUBSTANTIALLY MATCHING IN SHAPE WITH THAT OF THE HEATER SURFACE PORTION AND TO WHICH HEAT IS TO BE TRANSFERRED FROM SAID HEATER, SAID BODY HAVING A THERMAL COEFFICIENT OF EXPANSION DIFFERING FROM THAT OF THE HEATER RESISTANCE MATERIAL, AND A LAYER OF ELECTRICALLY AND THERMALLY CONDUCTIVE MATERIAL INTERPOSED BETWEEN SAID SURFACE PORTIONS FOR SECURING SAID HEATER AND BODY TO EACH OTHER AND FOR THE TRANSFER OF HEAT AND CONDUCTION OF ELECTRIC CURRENT THERETHROUGH BETWEEN SAID HEATER AND BODY, SAID LAYER COMPRISING A MIXTURE OF SMALL ELECTRICALLY AND THERMALLY CONDUCTIVE PARTICLES SELECTED FROM THE GROUP OF SILVER, SILVER-COPPER ALLOYS AND GRAPHITE MATERIALS DISPERSED THROUGHOUT A MATERIAL SELECTED FROM THE GROUP CONSISTING OF SILICONE RESIN, POLYIMIDE RESIN, BENZOPHENONE RESIN, POLYAMIDE-IMEDE RESINS, POLYBENZIMIDAZOLE RESINS, POLYBENZOTHIAZOLE RESINS, POLYETHYLENEIMINE RESINS, PHOSPHONITRILIC RESINS AND POLYESTER RESINS SO THAT SAID LAYER IS FLEXIBLE, ELASTIC AND CREEP-RESIS TANT AND STABLE AT TEMPERATURES ON THE ORDER OF AT LEAST 150*C. AND FREE OF COMPONENTS WHICH TEND TO DEGRADE THE PTC HEATER MATERIAL.
Claim 3
Dependent Claim
52 words
An assembly as set forth in claim 1 wherein said resin material is selected from the group consisting of silicone resin and polyimide resin and wherein said conductive particles comprise from 60 to 85 percent of the weight of said bonding layer and have an average particle size of about 1 micron.