Multi-Die TIM and Adhesive Layout to Prevent Package Delamination

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Solution Overview

Problem

In Three-Dimensional Integrated Circuits (3DICs), heat dissipation is hindered by delamination issues between the heat spreader and encapsulating materials due to poor adhesion, leading to reliability concerns.

Innovation Solution

A method involving the selective dispensing of adhesive layers between semiconductor dies and encapsulants, followed by the formation of a thermal interface material (TIM) that wraps the adhesive layers, improving adhesion between the TIM and encapsulating materials to enhance heat dissipation and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a heat spreader is adhered to semiconductor dies to dissipate heat, then heat dissipation capability is improved, but adhesion between the heat spreader and encapsulating materials deteriorates leading to delamination

Engineering Contradiction:

Improveheat dissipation capabilityVSAvoidadhesion between heat spreader and encapsulating materials

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

An adhesive layer is introduced as an intermediary between the heat spreader (thermal interface material) and the encapsulating materials (underfill and molding compound). This adhesive layer serves as a mediator that provides compatible bonding surfaces for both the metal heat spreader and the polymer-based encapsulating materials, thereby preventing delamination while maintaining effective heat dissipation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The packaging structure employs a composite material system consisting of multiple layers with different material properties: the heat spreader (metal), adhesive layer (polymer-based adhesive), underfill (epoxy resin), and molding compound (polymer). Each material is selected for its specific properties, and their combination creates a system that simultaneously achieves thermal conductivity, mechanical adhesion, and structural integrity.

Inventive Principle:

Principle #40Composite materials

2Strength

If adhesive layers are selectively dispensed to improve adhesion, then bonding strength between components is improved, but manufacturing process complexity increases

Engineering Contradiction:

Improvebonding strength between heat spreader and encapsulating materialsVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The adhesive layer is applied selectively only in specific locations where bonding is required - namely, at the interfaces between the heat spreader and the underfill, and between the underfill and the molding compound. This localized application approach provides targeted adhesion enhancement without requiring uniform coating across the entire heat spreader surface, thereby controlling manufacturing complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The adhesive layer is applied in advance before final assembly of the heat spreader with the encapsulating materials. This preliminary action ensures that the bonding surfaces are pre-prepared with adequate adhesive material, facilitating subsequent assembly steps and ensuring reliable bonding without requiring complex real-time adjustment mechanisms during manufacturing.

Inventive Principle:

Principle #10Preliminary 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

This approach reduces delamination issues and increases the reliability of heat dissipation in 3DICs by creating a robust thermal interface between the TIM and encapsulating materials, effectively addressing the adhesion challenges.

Implementation Method 1

improving adhesion between the TIM and the encapsulating materials

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

thermal interface material (TIM) that wraps the adhesive layers, improving adhesion between the TIM and encapsulating materials to enhance heat dissipation

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11894287B2Adhesive and thermal interface material on a plurality of dies covered by a lid

Publication Date: 2024.02.06 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Provided are a package structure and a method of forming the same. The package structure includes a first die, a second die group, an interposer, an underfill layer, a thermal interface material (TIM), and an adhesive pattern. The first die and the second die group are disposed side by side on the interposer. The underfill layer is disposed between the first die and the second die group. The adhesive pattern at least overlay the underfill layer between the first die and the second die group. The TIM has a bottom surface being in direct contact with the first die, the second die group, and the adhesive pattern. The adhesive pattern separates the underfill layer from the TIM.