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Modification of Thermosetting Dielectric Build-Up Materials for Imprinting PC Boards by Use of Small Hollow Glass Microspheres

IP.com Disclosure Number: IPCOM000012115D
Publication Date: 2003-Apr-09
Document File: 2 page(s) / 79K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that replaces the silica in the build-up resins of substrates with hollow glass microspheres. Benefits include improving CTE while lowering the dielectric constant.

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Modification of Thermosetting Dielectric Build-Up Materials for Imprinting PC Boards by Use of Small Hollow Glass Microspheres

Disclosed is a method that replaces the silica in the build-up resins of substrates with hollow glass microspheres. Benefits include improving CTE while lowering the dielectric constant.

Background

Currently, to lower the CTE of the epoxy build-up layers, raw material providers add silica filers.  Silica’s low CTE (~2 ppm) and small particle size make it an almost idea filler.  The key weakness, however, is that it has a higher dielectric constant (~4 for silica) than the epoxy resin.  Keeping the dielectric constant low is critical to meeting electrical performance targets in high performance packaging.

General Description

In the disclosed method, the particles not only fit in a ~50 micron thick dielectric layer, but do not interfere when imprinting features within 5 microns of the underlying core material. Imprinting micro-via features to 5 microns of the surface is important because of the need to clear the vias. If a chemical or plasma etch is used, the amount of material to be removed must be small relative to the 15 – 25 micron deep lines and traces. Otherwise, the lines and traces are severely eroded. If a large particle size microsphere is used, all the lines and traces will be over eroded, a show-stopper issue for the imprinting process.

The disclosed method describes a range of particle sizes (below ~5 microns) that allow hollow glass...