IC Package Heat Sink Trenches to Isolate TIM and Adhesive

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Solution Overview

Problem

Existing integrated circuit packages face issues with thermal interface material spreading and mixing with adhesive material during heat sink mounting, leading to chemical incompatibility and increased thermal resistance, which affects heat dissipation efficiency.

Innovation Solution

Incorporating a first trench surrounding the electronic chip in the encapsulation coating to contain the thermal interface material and a second trench for the adhesive material, controlling the thickness of the thermal interface layer and preventing mixing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If pressure is applied to mount the heat sink, then the thermal interface material layer thickness is reduced improving heat dissipation, but the thermal interface material spreads and mixes with the adhesive material causing chemical incompatibility

Engineering Contradiction:

Improvethermal interface material layer thicknessVSAvoidchemical compatibility

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The coating is segmented into distinct regions by forming trenches that separate the thermal interface material application area from the adhesive material application area. This segmentation prevents the spreading and mixing of materials while allowing independent control of each material's placement and thickness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The trench acts as an intermediary barrier between the thermal interface material and adhesive material. This intermediate structure physically isolates the two materials, preventing direct contact and chemical incompatibility while still allowing both materials to fulfill their respective functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If pressure is reduced when mounting the heat sink, then chemical incompatibility is avoided, but the thermal interface material layer thickness increases reducing heat dissipation efficiency

Engineering Contradiction:

Improvechemical compatibilityVSAvoidthermal interface material layer thickness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

By segmenting the coating area with trenches, the patent allows the thermal interface material to be contained within a specific region. This enables the use of reduced mounting pressure without excessive spreading, as the trench boundaries limit the material's lateral movement while maintaining adequate thermal contact.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The trench creates a localized containment area with specific geometric properties (depth, width, shape) that are optimized to hold the thermal interface material. This local structural modification provides different functional qualities in different regions: the trench bottom area accommodates the thermal interface material with controlled thickness, while the trench walls prevent spreading.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If the thermal interface material layer thickness is reduced, then heat dissipation efficiency is improved, but the risk of material spreading and mixing with adhesive increases

Engineering Contradiction:

Improvethermal interface material layer thicknessVSAvoidmaterial spreading

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The trench segments the coating surface into distinct functional zones, creating physical boundaries that contain the thermal interface material within its designated area. This segmentation prevents the material from spreading beyond the chip edges and mixing with the adhesive material applied in adjacent regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The trench structure is prepared in advance before applying the thermal interface material and adhesive. This preliminary structural preparation creates pre-defined barriers that prevent the harmful spreading effect before it can occur, allowing thin layers to be applied without the risk of excessive lateral flow and mixing.

Inventive Principle:

Principle #9Preliminary anti-action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Reduces thermal resistance by approximately 33% and enhances heat dissipation efficiency by controlling the thermal interface material thickness and preventing material mixing.

Implementation Method 1

a thermal interface material layer located between the electronic chip and the heat sink

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

fixed on said coating by an adhesive material

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS20250218884A1Integrated circuit package with heat sink and manufacturing method thereof

Publication Date: 2025.07.03 STMICROELECTRONICS (GRENOBLE 2) SAS

AI summary

A support substrate supports an electronic chip. An encapsulation coating on the support substrate coats the electronic chip. The encapsulation coating includes a trench surrounding the electronic chip. A heat sink is mounted to the encapsulation coating above the electronic chip. The heat sink is fixed to the encapsulation coating by an adhesive material and a thermal interface material layer is present between the electronic chip and the heat sink. The trench is positioned between the thermal interface material layer and the adhesive material.