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Method for micro-feature casting to fabricate package substrate design features

IP.com Disclosure Number: IPCOM000018914D
Publication Date: 2003-Aug-20
Document File: 3 page(s) / 663K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for micro-feature casting to fabricate package substrate design features. Benefits include improved process simplification.

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Method for micro-feature casting to fabricate package substrate design features

Disclosed is a method for micro-feature casting to fabricate package substrate design features. Benefits include improved process simplification.

Background

         Imprinting is a thermal forming/embossing process. Material is displaced and flows due to pressure and temperature, leaving residual material in the vias. Total thickness variation (TTV) across the wafer of the build-up layer (BUL) tends to be difficult to control. Plasma etch removes residual material in the vias. Planarization of the substrate is performed in features, such as traces and vias, to remove overplating and expose the features (see Figure 1).

         The imprinting process is the conventional solution for creating electrical paths. However, some improvements are required. The number of process steps must be reduced and TTV must be more tightly controlled to make planarization easier.

General description

         The disclosed method is micro-feature casting to fabricate package substrate design features.

A liquid dielectric material, such as epoxy, flows and fills the features. The flow process step enables self-leveling of the dielectric material, creating a very uniform and controlled thickness across the substrate and features. The process is similar to injection molding, except that the material is flowed into the features rather then injected under high pressure.

         The key elements of the method include:

•         Casting mold with micron-size features.

•         Controlling the thickness variation across the substrate package, using flow-able liquid dielectri...