high density interconnect structure comprises a dielectric layer 122 and a patterned metallization layer 128 the dielectric layer 122 has separate lower and upper sublayers 124 and 126 respectively the sublayer 124 is a thermoplastic adhesive such as ultem u00ae 1000 polyetherimide resin available from general electric company and the sublayer 126 is a kapton u00ae polyimide thermoset film available from e i du pont de nemours company the metallization 128 extends down into a via hole 127 and into ohmic contact with the contact pad 118 the sidewalls of the via hole are sloped upward and outward as a result of its formation by laser drilling a second layer 130 of the high density interconnect structure is disposed on layer 120 and comprises a dielectric layer 132 and a patterned metallization layer 138 the dielectric layer 132 is a spun on thermoplastic layer such as spi siloxane polyimide available from huls america for failure analysis we cross sectioned multilayer laminates which we made previously in which each dielectric layer consisted of a thermoplastic lower layer and a thermoset upper layer and in which via connections were destroyed during the process of laminating subsequent dielectric layer fig2 illustrates a small portion of such a cross section the cross sectioned high density interconnect structure 200 includes laminated first and second dielectric layers 222 and 232 respectively this structure comprises a chip 216 having a contact pad 218 on its upper surface a first layer 220 of the.