Reinforced plastics carrier for printed circuits
AssigneeKoninklijke Papierfabrieken Van Gelder Zonen N.V.
InventorHendrik Jongetjes
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Abstract
Non-woven glass-fiber webs for reinforcing plastics material carrying printed circuits are produced by the wet process from E-glass fibers bonded with polyvinyl alcohol. The polyvinyl alcohol used is a powder or suspension, has a degree of hydrolization of 98 - 100%, and a viscosity, as a 4% solution in water of 20.degree.C, of 20-100 cP. Preferably the polyvinyl alcohol has a degree of swelling at 20.degree.C of between 3 and 8, and in the dry form a particle size of between 50 and 180 .mu.. A plurality of these glass fiber webs are impregnated with a solution of an epoxy resin, arranged as a laminate, then compressed at elevated pressure and temperature to form the final laminate.
Claims4
A process for making an insulating sheet for printed circuits, which comprises the steps of forming a 0.005-0.05% suspension of fibers and particulate binder in water, said fibers being fibers of E glass 5-30 mm long and 5-15 .mu. thick and said binder being a particulate polyvinyl alcohol having a degree of hydrolization of 98-100%, being present in the amount of 5-25% based upon weight of the glass fibers, said binder having a particle size of 50-180 m.mu. and a degree of swelling of 20.degree.C of 3-8, and having a viscosity measured as a 4% solution in water at 20.degree.C. of 20-100 cP;
- processing this suspension on a fiber web making machine by dewatering to form a non-woven glass fiber web;
- drying said glass fiber web by heating to a temperature of 85.degree.-100.degree.C to dissolve the polyvinylalcohol granules in their own swelling water and subsequently further heating to an increased temperature to evaporate the water and dehydrate and harden the polyvinyl alcohol;
- impregnating a plurality of said glass fiber webs with a solution of an epoxy resin and hardener in acetone, evaporating the acetone;
- arranging said plurality of webs as a laminate;
- and compressing said webs into an insulating sheet laminate at elevated pressure and temperature.
Dependencies are inferred from the claim text.