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Flex Substrate Packaging Selective Solder Resist Opening in Substrate Fold Area

IP.com Disclosure Number: IPCOM000074593D
Publication Date: 2005-Feb-23
Document File: 2 page(s) / 73K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that selectively adds a solder resist opening in the flex substrate fold area. Benefits include reducing delamination and package cracking.

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Flex Substrate Packaging Selective Solder Resist Opening in Substrate Fold Area

Disclosed is a method that selectively adds a solder resist opening in the flex substrate fold area. Benefits include reducing delamination and package cracking.

Background

There is a need to reduce stress and release trapped solvents and moisture in the solder resist to improve solder reliability and reduce package cracking in the fold area. Currently, thermal steps are added to the assembly flow to provide for moisture and substrate component out-gassing
(see Figure 1).

General Description

In the disclosed method, the solder resist openings achieve localized stress relief in the fold area, and create vent openings for moisture out-gassing (see Figure 2). The solder resist opening is created using the standard photolithographic technique. In addition, the disclosed method does not add costs to the process, since it is created simultaneously with the wire bond pad and ball interconnection pad openings.

Advantages

The following are advantages of the disclosed method:

§         Creates localized stress relief in the fold area

§         Provides for the out-gassing of moisture and other elements

§         Reduces delamination and package cracking in the fold area

§         Maintains process costs

Fig. 1

Fig. 2

Disclosed anonymously