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Photoimagable solder mask coating

  • US 5,089,376 A
  • Filed: 06/13/1989
  • Issued: 02/18/1992
  • Est. Priority Date: 12/08/1986
  • Status: Expired due to Fees
First Claim
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1. A solder mask coating composition comprising:

  • 1) a resin binder,

         2) a crosslinker,

         3) a UV sensitive polymer which has a carboxyl moiety and

         4) an acid functional acrylate ester of a bisphenol A epoxy resin in an amount of from about 7 to about 28% by weight of the total solids wt., further providing that the UV sensitive polymer was made by condensing a reaction mixture of component (A), a diisocyanate having from 6 to 18 carbon atoms;

    component (B) a carboxylic acid polyol having the formula;

    (OH)x --R6--COOH, wherein x can be an integer from 2 to 5, and wherein R6 is a linear or branched, saturated, unsaturated, or aromatic hydrocarbon moiety having from 2 to 29 carbon atoms; and

    component (C) a hydroxy alkyl(meth)acrylate wherein its alkyl group has from 2 to 28 carbon atoms;

    provided that component (A) is present in an amount of from about 30 to about 80% by weight of the total amount of the reaction mixture;

    component (B) is present in an amount of from about 5 to about 45% by weight of the total amount of the reaction mixture and has a minimum of about 0.3 milliequivalents of acid per gram of the total amount of the reaction mixture; and

    component (C) is present in an amount of from about 5 to about 50% by weight of the total amount of the reaction mixture with a minimum amount of 0.5 milliequivalents of acrylate per gram of the total amount of the reaction mixture;

    wherein the UV sensitive polymer is characterized by its hydrophilic nature;

    further providing that a solder mask coat prepared from the coating composition is soluble or swellable in aqueous solutions having a pH in excess of 7.5 until exposure to UV light.

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