Thick-film circuit on a substrate with through-contacts between conductor paths on opposite sides of the substrate

Claim 1

In a thick film circuit structure of the type comprising an electrically insulative ceramic substrate in the form of a flattened structure having a pair of opposed, generally parallel side faces and having at least on through hole extending therethrough from one such face to the other thereof, said substrate having conductor paths deposited upon each of said side faces, at least one such conductor path on each said side face being located in adjacent relationship to the perimeter of such one through hole, the improvement which comprises a conductive path extending through and substantially completely filling such one through hole, said conductive path being formed by the steps of a. filling substantially completely such one through hole in a ceramic substrate with a paste composition comprising on a 100 weight percent total weight basis 1. from about 48 to 64 weight percent of gold in the form of particles at least about 90 weight percent of which have number average particle sizes not greater than about 10 microns and not more than about 5 weight percent of which are larger than about 25 microns, 2. from about 3 to 9 weight percent of an inorganic binder comprised of a preformed fritted glass in the form of particles having a number average size of less than about 30 microns and characterized by a capacity to sinter when exposed to temperatures ranging from about 800° to 1000° C., said glass comprising on a 100 weight percent total glass wight basis from about 30 to 65 weight percent PbO from about 8 to 35 weight percent SiO 2 from about 0.5 to 7 weight percent Al 2 O 3 from about 0 to 10 weight percent TiO 2 said glass further optionally containing: from about 10 to 30 weight percent B 2 O 3 in combination with from about 10 to 30 weight percent LiO and from about 10 to 30 weight percent CdO by replacement of up to about 25 weight percent of each of said PbO and said SiO 3 therewith,