Circuit board prepreg with reduced dielectric constant
AssigneePolyclad Laminates, Inc.
InventorsRobert J. Sanville, Jr., Carl P. Kernander
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Abstract
This invention involves a prepreg composition and procedure for use in forming printed circuit boards with reduced and uniform dielectric constant, improved thermal expansion characteristics, and uniform appearance. The prepreg composite is a resin impregnated substrate and has a reduced dielectric constant as low as 3.5. It contains 5-30% by resin volume of hollow inorganic microsphere filler whose diameters are less than 40 micrometers, and the uniform distribution of the hollow inorganic microspheres is controlled by the presence of hydrophobic fumed silica or other similar flow modifier.
Claims20
A filled prepreg composite having a uniform reduced dielectric constant comprising:
- (a) resin;
- (b) 5-30% by volume of resin solids of hollow inorganic microsphere filler;
- (c) support material;
- and
- (d) sufficient hydrophobic, finely divided silica flow modifier to produce and maintain uniform distribution of the hollow inorganic microspheres in the resin.
A filled prepreg composite having a uniform, reduced dielectric constant, comprising:
- (a) resin;
- (b) 5-30% by volume of resin solids of hollow inorganic microsphere filler;
- (c) support material;
- and
- (d) means to produce and maintain uniform distribution of the hollow inorganic microspheres in the resin.
Dependencies are inferred from the claim text.