Abstract: A photoimageable composition, useful as a photoresist for forming a printed circuit board, is both alkaline aqueous developable but, subsequent to exposure and development, is processable in highly alkaline environments, such as additive plating baths and ammoniacal etchants. The photoimageable composition is tack-free and is resistance to polymerization inhibition by oxygen, and is therefore particularly suitable for contact printing. The photoimageable composition comprises A) between about 25 and about 75 wt % of a binder polymer, B) between about 20 and about 60 wt % of a photopolymerizeable material which is a multifunctional photopolymerizeable monomer or short chain oligomer, and C) between about 2 and about 20 wt % of a photoimageable chemical system, the weight percentages being based on the total weight of components A)-C).

Abstract: In a dry film laminate useful in the printed circuit industry comprising a support sheet, a photoimageable composition layer and a protective sheet, a dual intermediate layer is interposed between the photoimageable composition layer and the support sheet. The intermediate layer consists of a water-soluble tie coat in contact with the photoimageable composition layer and a top coat in contact with the support sheet, the top coat being insoluble in neutral or acidic aqueous solution but soluble in dilute alkaline aqueous solution.

Abstract: A photoimageable composition for forming a solder mask has a photopolymerizable acrylate chemical system which renders exposed portions insolvable to alkaline aqueous developers and an epoxy chemical system which hardens the composition after exposure and development. The acrylate chemical system comprises acrylate monomers, epoxy-acrylate oligomers and a photoinitiator. The epoxy chemical system comprises an epoxy resin and a curative therefore. The composition further comprises a cross-linking agent which is reactive with hydroxyl groups of the acrylate and epoxy chemical systems.

Abstract: A printed circuit assembly includes surface mounted circuit components held in place on a printed circuit board by a rigid connection. The outwardly extending leads of the circuit component are bonded to conductive areas of the board by an electrically conducting flexible adhesive. The combination of a rigid mechanical connection between the body portion of the circuit component and the board and a flexible, electrically conductive connection between each lead end and the board provides an arrangement capable of withstanding shock loading, as well as vibrational and bending forces to which the assembly might be subjected. The assembly lends itself to relatively inexpensive circuit boards produced by printing techniques, typically including applied metal buses that serve as low resistance shunts to the power connections of the circuit components.