Abstract In making a lead assembly, for example for connection to integrated circuit or semi-conductor devices, layers of a lead metal, such as, nickel or nickel alloy, are provided on selected areas of both surfaces of a relatively thick base metal sheet, for example, of copper or copper alloy, which is etched through using the lead metal layers as a mask for precisely determining the portions of the base metal sheet to be removed, with the remaining parts of the base metal sheet and the lead metal layers integral therewith defining the assembly of leads which are joined by an outer frame to be severed from the leads after the connection of the latter to electrodes of integrated circuits or semi-conductor devices. The lead metal layers on one surface of the base metal plate may extend beyond the lead metal layers on the other plate surface so that, upon etching through the base metal plate from both surfaces thereof, the lead metal layers on said one surface of the base metal plate project beyond the remaining parts of the latter to constitute tips of the corresponding leads.
The method according to claim 1, in which each said lead metal layer is applied to said base metal plate by electrolytic plating on the latter.
Claim 2
Dependent Claim
85 words
The method according to claim 1, in which each said lead metal layer is applied in the respective pattern by first depositing a photo-resist layer on the related surface of the base metal plate, exposing and developing said photo-resist layer to have portions of the latter on said base metal plate in a negative to said respective pattern, and then plating said lead metal layer on the areas of said related surface of the base metal plate which are free of the developed photo-resist layer.
Claim 3
Dependent Claim
72 words
The method according to claim 1, in which each said lead metal layer is applied in the respective pattern by first forming said lead metal layer on the entire area of the related surface of the base metal plate, depositing an etch-proof layer on said metal layer in said respective pattern, and then etching away the portions of said lead metal layer which are exposed by said pattern of the etch-proof layer.
Claim 4
Dependent Claim
98 words
The method according to claim 1, in which said pattern of each said lead metal layer further includes elongated portions of the respective lead metal layer which are spaced from said frame and from said lead arms, and, prior to the selective removal of said base metal plate by said etchant at said areas free of the lead metal layer on either of said surfaces, an insulating plate is joined to said lead metal layer on said one surface at said lead arms and at the portions thereof corresponding to said Elongated portions of the lead metal layer.