The technology of polymer thick film is merging as a method to increase package density withbenefiting from cost reduction of the PCB. This technology has several critical parameters that must befollowed to insure that the proper results can be obtained in processing the PCB. The considerations of hightemperature storage or (heat storage) reflow solder, and chemical resistance are critical parameters in theselection of a stable PTF resistor system.Stability of the resistor system can be assessed by subjecting the printed and cured product to such tests assolder lest at 260 degrees centigrade for 30 seconds, high temperature storage at 125 degrees centigrade, for1000 hours, thermal shock -25 degrees centigrade to +125 degrees centigrade, cycled 500 times.These controls of process are the selection of the proper screen type, emulsion thickness, squeegeeselection for hardness as well as the proper curing condition.
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