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Controlling Solder TIM Bond Line Thickness by Substrate Reference Design and Solder Sealant

IP.com Disclosure Number: IPCOM000020305D
Publication Date: 2003-Nov-12
Document File: 3 page(s) / 53K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that controls solder TIM bond line thickness by using the same solder material (or different solder materials with a lower melting temperature than the solder TIM materials) to automatically accomplish the substrate reference design. Benefits include improving solder TIM reliability, achieving stable solder TIM bond line thickness and eliminating sealant delamination.

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Controlling Solder TIM Bond Line Thickness by Substrate Reference Design and Solder Sealant

Disclosed is a method that controls solder TIM bond line thickness by using the same solder material (or different solder materials with a lower melting temperature than the solder TIM materials) to automatically accomplish the substrate reference design. Benefits include improving solder TIM reliability, achieving stable solder TIM bond line thickness and eliminating sealant delamination.

Background

Current sealant materials are polymers, which commonly get gelled and cured before the solder TIM is melt. Therefore, solder TIM BLT depends on solder pre-form thickness, the reflow profile, clip force as well as the degree of cure of the polymer sealant material. The process requires a higher clip force, which may lead to warped substrates and a higher rework rate for PGA parts.

General Description

The disclosed method uses the same solder TIM material (or a material with a lower melting temperature) as sealant materials. There are two methods to apply the solder sealant:

  • Substrate suppliers make pre-solder on substrate, the pre-solder can be with different patterns (continuous or with breaks), depending upon product design or other requirement. During the lid attach process, the same flux is applied to both the TIM and pre-solder patterns, and then the lid attach is completed (see Figure 1).
  • The solder paste is applied on pre-patterned metal pads on the substrates during the IHS process, and then the lid attach is completed (see...