LAMINATION OF A PHOTOPOLYMERIZABLE SOLDER MASK LAYER TO A SUBSTATE CONTAINING HOLES USING AN INTERMEDIATE PHOTOPOLYMERIZABLE LIQUID LAYER

摘要

A process is disclosed for applying a preformed photopolymerizable solder mask film and a photosensitive liquid to a printed circuit substrate containing a plurality of holes wherein reduced failure is obtained in photopolymerized areas of the solder mask film above the holes as determined after a soldering operation. The photosensitive liquid contains at least one ethylenically unsaturated compound capable of forming a high polymer by addition polymerization and a first photoinitiator system which has an absorption maximum in a first spectral region. The preformed photopolymerizable film contains at least one ethylenically unsaturated compound capable of forming a high polymer by addition polymerization and a second photoinitiator system, such that the preformed photopolymerizable film has an absorption maximum in a second spectral region and is activated by actinic radiation therein and has an absorption minimum in the first spectral region and transmits actinic radiation therein.