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Method for wire-bonded spacers for exact BLT control of TIMs

IP.com Disclosure Number: IPCOM000020171D
Publication Date: 2003-Oct-29
Document File: 4 page(s) / 53K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for wire-bonded spacers for exact bond-line thickness (BLT) control of thermal interface materials (TIMs). Benefits include improved functionality, improved reliability, and improved performance.

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Method for wire-bonded spacers for exact BLT control of TIMs

Disclosed is a method for wire-bonded spacers for exact bond-line thickness (BLT) control of thermal interface materials (TIMs). Benefits include improved functionality, improved reliability, and improved performance.

Background

The conventional solution is seen in see figures 1 & 2. Thermal interface material is deposited on the silicon die. An IHS is placed on top and the package is placed in compression. Exact control of the TIM BLT can be difficult in practice and is determined indirectly by applied-force, TIM and sealant viscosity, and the IHS cavity shape (see Figure 2). The thickness of the TIM after cure depends on how deeply the IHS sinks into the TIM and sealant. An excessively thick TIM BLT increases the thermal resistance of the package. An excessively thin TIM BLT can lead to inferior package reliability.

The conventional methods of controlling the TIM BLT include:

•         Controlling the physical properties, as well as dispense pattern (and amount) of TIM and sealant

•         Controlling the force applied on top of the IHS for clamping during cure

•         Control of the cure time and temperature

General description

The disclosed method is one or more wires strung over the silicon die, which are anchored to the package via wire bonding. After application of the TIM and the IHS, these wires function as spacers, providing direct control over the BLT.

         The key elements of the method include:

•         Metal wire (such as aluminum or gold), which is strung over silicon

•         Ends of the wire that are anchored to either the silicon or the substrate via wire bonding

Advantages

         The disclosed method provides advantages, including:

•         Improved functionality due to providing direct control over the TIM BLT

•         Improved functionality due to providing th...