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Substrate Soldermask Barrier and Trough to Control Die Attach Bleed Out for all Die to Substrate Applications

IP.com Disclosure Number: IPCOM000009964D
Publication Date: 2002-Oct-02
Document File: 5 page(s) / 168K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for creating a control barrier to prevent die attach bleed out. The method prevents bleed out by applying additional soldermask, or by creating a trough in the soldermask. Benefits include improved assembly yield and an increase in wirebound reliability.

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Substrate Soldermask Barrier and Trough to Control Die Attach Bleed Out for all Die to Substrate Applications

Disclosed is a method for creating a control barrier to prevent die attach bleed out. The method prevents bleed out by applying additional soldermask, or by creating a trough in the soldermask. Benefits include improved assembly yield and an increase in wirebound reliability.

Background

Currently, die attach bleed out is controlled by the volume of epoxy, cure profile, viscosity, and the dispense pattern. Bleed out can affect single and stacked die wirebonding by contaminating bond pads, resulting in pad lift, delamination, etc. To avoid bleed out, the size of a die that can be placed on a given substrate is reduced. Current maximum allowable die attach bleed out is specified at 330um. If a barrier were in place to minimize the bleed-out to less than 330um:

 

  • a larger die can be placed on the substrate
  • more bond fingers can be place on the substrate

General Description

The disclosed method describes two ways to prevent die attach bleed out:

 

  • Soldermask barrier. The soldermask barrier is applied in front of all bond fingers during substrate manufacturing. Barrier size is a minimum of 1 mil in height and 2 mil in width, to enable larger die placement and more real estate on the substrate.
  • Soldermask trough. The soldermask trough depth is proportionate to the height of the soldermask applied in the surrounding area. A trough width of 50um is recommended. The trough acts as...