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Method for attaching a die to an IHS using a differential phase-change TIM

IP.com Disclosure Number: IPCOM000022265D
Publication Date: 2004-Mar-03
Document File: 3 page(s) / 69K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for attaching a die to an integrated heat spreader (IHS) using a differential phase-change thermal interface material (TIM). Benefits include improved performance and improved process simplicity.

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Method for attaching a die to an IHS using a differential phase-change TIM

Disclosed is a method for attaching a die to an integrated heat spreader (IHS) using a differential phase-change thermal interface material (TIM). Benefits include improved performance and improved process simplicity.

Background

A sealant material is conventionally used to mechanically affix an IHS to a die and substrate.

The conventional method can be implemented using the following steps:

1. Dispense TIM on top of a die attached to a substrate component.

2.         Dispense sealant on to the substrate component at a location that mates with the periphery of the IHS.

3. Place an IHS on the die and substrate component at a location that mates with the sealant.

4.         Apply a force and heat source to the component to cure the TIM and mechanically fix the IHS to the die and substrate component.

         Conventionally, the TIM and sealant material are dispensed on top of the die and on the substrate. An IHS lid is then placed on the die and substrate and mated with the sealant. The entire piece is secured by spring clips and heated in an oven to cure both the sealant and the TIM (see Figure 1).

General description

         The disclosed method is the application of a die cut, thixotropic, free standing, differential phase-change (DPC) TIM to a die and substrate and the attachment of an IHS. Alternatively, TIM is applied to the IHS and a pick-and-place machine attaches it to the die and substrate.

The use of a sealant to mechanically fix a die to an IHS is eliminated.

         The key element of the method is the DPC TIM, which has the following characteristics:

•         Thixotropic and functions like an adhesive polymer (with an adhesive strength of 25 PSI) when it is kept below its reflow temperature

•         Operating temperature between -60°C and + 200°C

•         Laminar flow to wet and fill voids between the die and heat sink surfaces

•         Relatively low reflow temperature (<981°C)

•         Relatively low mounting forces (<15 PSI)

•         Low thermal resistances (<0.06 C/W/in2)

•         Thermoplastic, which can be reheated above its reflow temperature, moved, reworked, reset, and resolidified

•         Molten or solid state with relatively no change in thermal conductivity or thermal resistance

•         Environmentally friendly and non-toxic, containing only ingredients that are FDA approved as food ingredients, for food contact, or...