Flexible Heat Spreader Assembly for Thin Semiconductor Packages

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Solution Overview

Problem

Existing semiconductor packages face challenges in achieving high thermal and mechanical performance while maintaining compactness and high circuit density, particularly in preventing chip overheating due to inadequate heat dissipation and structural integrity.

Innovation Solution

The use of a flexible heat spreader with high thermal conductivity, such as a graphite sheet, attached to the chip and molding compound using a thermal interface material, facilitates efficient heat dissipation through a horizontal thermal path, preventing overheating and enhancing mechanical protection against rigid objects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a rigid heat spreader is used, then heat dissipation performance is improved, but package thickness increases and flexibility to conform to chip profiles is reduced

Engineering Contradiction:

Improveheat dissipation performanceVSAvoidpackage thickness

Core Design Contradiction:

TemperatureVSLength of stationary object

Solution Approach 1:

The patent applies this principle by using a flexible heat spreader made of thin film material that can conform to chip profiles while maintaining effective heat dissipation. The flexible nature allows the heat spreader to be attached to irregular surfaces without requiring excessive thickness, thus resolving the contradiction between heat dissipation performance and package thickness.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the physical parameters of the heat spreader by using materials with specific thermal conductivity and flexibility characteristics. By optimizing the thickness and material composition, the heat spreader achieves adequate thermal performance while maintaining a thin profile that reduces overall package thickness.

Inventive Principle:

Principle #35Parameter changes

2Length of stationary object

If a flexible heat spreader is used, then package thickness is reduced and conformity to chip profiles is improved, but structural rigidity and mechanical protection are reduced

Engineering Contradiction:

Improvepackage thicknessVSAvoidmechanical protection

Core Design Contradiction:

Length of stationary objectVSStrength

Solution Approach 1:

The patent applies this principle by creating a composite structure where a flexible heat spreader is combined with a rigid support layer. The flexible heat spreader provides thermal management and conformability, while the rigid support layer restores structural integrity and mechanical protection. This composite approach resolves the contradiction between flexibility/thinness and mechanical strength.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent merges the flexible heat spreader with the rigid support layer into a single integrated component. This combination allows the assembly to provide both the flexibility needed for conforming to chip profiles and the rigidity needed for mechanical protection, effectively resolving the contradiction between these opposing requirements.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If existing semiconductor package structures are used, then manufacturing simplicity is maintained, but thermal and mechanical performance are insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidthermal and mechanical performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies this principle by pre-attaching the flexible heat spreader to the chip before the molding process. This preliminary action ensures proper thermal contact and positioning, while the subsequent molding process automatically provides mechanical support and protection. This sequence maintains manufacturing simplicity while achieving improved thermal and mechanical performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent makes the molding compound serve multiple functions: it provides mechanical protection, structural support, and thermal management assistance. By making the molding compound rigid and integrating it with the flexible heat spreader assembly, the package structure achieves enhanced thermal and mechanical performance without significantly complicating the manufacturing process.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This solution effectively dissipates heat generated by chips, preventing overheating and improving thermal and mechanical performance by utilizing a flexible heat spreader that can conform to chip profiles and reduce package thickness, while also protecting chips from damage.

Implementation Method 1

applying a thermal interface material to a first surface of the heat spreader facing the chip... facilitates efficient heat dissipation through a horizontal thermal path

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11862528B2Method for forming semiconductor package

Publication Date: 2024.01.02 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method of forming a semiconductor package is provided. The method includes mounting a chip on a package substrate. The method further includes placing a heat spreader over the chip and applying a thermal interface material to a first surface of the heat spreader facing the chip. The heat spreader is flexible. In addition, the method includes attaching the heat spreader to the chip through the thermal interface material by rolling a rod over a second surface of the heat spreader, and the second surface is opposite to the first surface.