Electronic package assembly method

The method for making plural electronic package assemblies, each of said assemblies having a ceramic pin carrier member, plural conductive elongated pluggable pins carried by said member, each of said pins being extended through said member to provide first and second extensions past first and second surfaces, respectively, of said member, a thin flexible printed circuit conductive member having a polyimide substrate of a predetermined thickness of substantially 5 microns, a printed circuit pattern of plural conductors supported by said substrate, said first extensions being bonded to predetermined ones of said plural conductors, and at least one electronic circuit chip having a high density array of input/output terminals bonded to preselected ones of said plural conductors, each said chip being thermally backbonded to a rigid thermal conductive member, said method comprising the steps of:

• providing a temporary planar support panel of etchable material,
• spraying an integral layer of uncured liquid polyimide on one surface of said support sufficient to provide said predetermined thickness when said polyimide is subsequently cured,
• drying said liquid polyimide layer,
• curing said dried polyimide layer,
• evaporating successive integral layers of chromium, copper and chromium on said polyimide layer,
• circuitizing said layers with plural said predetermined printed circuit patterns of plural conductors,
• removing first portions of said circuitized last mentioned chromium layer from said preselected ones of said conductors to provide first bonding sites for said chip terminals on said circuitized copper layer, and concurrently removing second portions of said circuitized last mentioned chromium layer from said predetermined ones of said conductors to provide second bonding sites for said first extensions of said pins on said circuitized copper layer, said printed circuit patterns providing an aperture at each of said second bonding sites through said evaporated layers,
• providing at least one said electronic circuit chip for each of said assemblies,
• bonding said terminals of each said chip to said first bonding sites of a mutually exclusive one of said plural circuit patterns by a controlled collapse chip connection process,
• selectively etching away with a compatible etchant third portions of said temporary support panel through an etchant mask to form plural accesses to the noncircuitized side of said polyimide layer, each of said accesses being larger than and beneath one of the printed circuit patterns to be included in each said assembly,
• piercing said polyimide layer through said apertured second bonding sites with a heated piercing tool,
• providing said ceramic pin carrier member and said plural conductive pins thereof for each of said assemblies,
• passing said first extensions of said pins of said pin carrier members through said pierced polyimide member and said apertured second bonding sites,
• solder reflow bonding said first extensions to said second bonding sites,
• selectively cutting the polyimide layer around each assembly site to separate the remainder of said temporary support panel therefrom, and
• thermally backbonding each of said chips to its associated said rigid thermal conductive member.