Coplanar Heat Sink and TIM Assembly for Package Warpage

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Solution Overview

Problem

Integrated circuit packages experience warpage due to material differences, leading to delamination issues between thermal interface material and device dies or packages, particularly at corners and weakly adhered surfaces.

Innovation Solution

The implementation of adhesive features and heat sink structures to reduce warpage and delamination by using flowable adhesive materials and heat sinks with integrated bars to provide mechanical support and ensure proper adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If adhesive features are added to reduce delamination, then TIM coverage improves, but device complexity increases

Engineering Contradiction:

ImproveTIM coverageVSAvoidpackage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The adhesive is segmented into discrete adhesive features positioned at specific locations (corners and edges of the package) rather than applying adhesive uniformly across the entire package. This segmentation allows the adhesive to target critical areas where delamination is most likely to occur, improving TIM coverage without requiring complex full-surface adhesive application mechanisms.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Adhesive features are placed locally at critical positions (corners and edges) where delamination risk is highest, rather than uniformly distributing adhesive across the entire package. This local quality approach concentrates adhesive resources where they are most needed, improving TIM coverage at critical interfaces without adding overall structural complexity.

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If heat sink with bar is used to reduce warpage, then package stability improves, but device complexity increases

Engineering Contradiction:

Improvewarpage reductionVSAvoidheat sink structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

A bar is added to the heat sink structure that extends in a direction perpendicular to the heat flow path, creating a dimensional enhancement that provides mechanical support against warpage without interfering with the thermal conduction function. This dimensional addition stabilizes the package by reinforcing the heat sink's structural integrity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The heat sink structure is designed to perform multiple functions: it conducts heat away from the package (thermal management) and simultaneously provides mechanical support to reduce warpage through the integrated bar (structural stabilization). This multi-functionality reduces the need for separate components, managing complexity while improving stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If adhesive features are dispensed at higher positions, then TIM adhesion improves, but manufacturing precision requirements increase

Engineering Contradiction:

ImproveadhesionVSAvoidadhesive feature positioning

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The adhesive features are dispensed at elevated positions before the TIM is applied, allowing the adhesive to be placed with relaxed precision requirements. The TIM is then pressed down during bonding, which forces the adhesive features into proper contact positions, compensating for any initial positioning variations and reducing the stringency of manufacturing precision requirements.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

By placing adhesive features at higher positions beforehand, the design creates a cushioning effect where the TIM pressing operation can accommodate positioning variations. The elevated adhesive features act as a buffer, allowing for greater tolerance in the dispensing process while still achieving reliable adhesion after the TIM is bonded down.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 warpage by up to 9.8% and improves TIM coverage from 94-95% to 98-99%, effectively minimizing delamination and enhancing thermal interface material adherence.

Implementation Method 1

adhering a lid to the package component using the flowable adhesive material

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

thermal interface material may be used to conduct heat from the devices in the integrated circuit packages to heat sinks

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250210455A1Coplanar control for film-type thermal interface

Publication Date: 2025.06.26 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes bonding a first package and a second package over a package component, adhering a first Thermal Interface Material (TIM) and a second TIM over the first package and the second package, respectively, dispensing an adhesive feature on the package component, and placing a heat sink over and contacting the adhesive feature. The heat sink includes a portion over the first TIM and the second TIM. The adhesive feature is then cured.