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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) / 72K

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...