Circuitized structures produced by the methods of electroless plating

Abstract

The present invention provides new methods for electroless plating of metal particularly gold and copper onto substrates, such as circuitized substrates, which reduces processing steps, reduces metal consumption, and reduces the scraping of parts due to contamination. The method employs a permanent plating resist. The method for electrolessly plating metal onto a substrate, including the following steps: providing: an uncured, photoimagable, dielectric permanent plating resist comprising: from about 10 to 80% of phenoxy polyol resin which is the condensation product of epichlorohydrin and bisphenol A, having a molecular weight of from about 40,000 to 130,000; from about 20 to 90% of an epoxidized multifunctional bisphenol A formaldehyde novolac resin having a molecular weight of from about 4,000 to 10,000; from 0 to 50% of a diglycidyl ether of bisphenol A having a molecular weight of from about 600 to 2,500; and from about 0.1 to 15 parts by weight of the total resin weight, a cationic photoinitiator; applying the permanent plating resist on the substrate; photopatterning the permanent plating resist to form apertures therein which expose areas of the substrate; and electrolessly plating metal onto the exposed areas of the substrate. The permanent plating resist is useful to protect the substrate areas including for example metallized features on the substrate, from the electroless deposition of metal during electroless plating; thus selective plating of metal is achieved. The permanent plating resist is not degraded by conventional gold or copper electroless baths. The invention also relates to circuitized structures produced by the methods of electroless plating.