Semiconductor Package Metal TIM Structure to Prevent Re-Melting

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Solution Overview

Problem

Conventional solid thermal interface materials (TIMs) have low thermal conductivity, and indium TIMs have a low melting point, leading to re-melting issues during subsequent packaging processes, which results in voids and low coverage.

Innovation Solution

A semiconductor package with a built-in thermal conductive structure, where a first metal TIM is plated on the package, followed by a dielectric layer and a second metal TIM bonded to the first, using metals like copper for enhanced thermal conductivity and high melting points to prevent re-melting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional solid TIMs are used, then the packaging process is simple, but the thermal conductivity is low

Engineering Contradiction:

Improvethermal conductivityVSAvoidpackaging process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses composite material structure with multiple metal layers (copper, aluminum, or aluminum alloy) combined with dielectric layers to create a TIM with superior thermal conductivity. The composite structure integrates different materials to achieve both high thermal performance and structural stability during packaging processes.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameters by using metals with high melting points (copper: 1085°C, aluminum: 660°C) and high thermal conductivity instead of conventional solid TIMs. This parameter change ensures the TIM remains stable during reflow soldering while maintaining excellent heat dissipation performance.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If indium TIMs are used, then the thermal conductivity is improved, but the TIM melts during subsequent packaging processes

Engineering Contradiction:

Improvethermal conductivityVSAvoidmelting point

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent fundamentally changes the temperature parameter by selecting metal materials with melting points significantly higher than the packaging process temperatures. Copper (1085°C) and aluminum (660°C) are used instead of indium, ensuring the TIM remains solid and stable during reflow soldering while maintaining high thermal conductivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite metal-dielectric structures where metal layers provide high thermal conductivity and high melting point stability, while dielectric layers provide structural support and insulation. This composite approach achieves both thermal performance and thermal stability during packaging.

Inventive Principle:

Principle #40Composite materials

3Reliability

If metal TIMs with high melting points are used, then re-melting is prevented, but the manufacturing complexity increases

Engineering Contradiction:

Improvestructural integrityVSAvoidmanufacturing ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by forming the metal TIM layers and dielectric layers before the reflow soldering process. The TIM structure is pre-established with proper material selection and layer configuration, so it automatically maintains structural integrity during subsequent high-temperature packaging without requiring additional protective measures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The metal TIM structure serves multiple functions simultaneously: it provides thermal conduction, structural stability during reflow, and acts as an integral part of the package substrate. This multi-functionality reduces the need for separate components and simplifies the overall manufacturing process despite the advanced material usage.

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

The solution achieves better thermal conductivity and prevents re-melting issues during packaging processes, ensuring effective heat dissipation and maintaining the structural integrity of the TIM.

Implementation Method 1

a first metal TIM is plated on the package... using metals like copper for enhanced thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

indium TIMs has low melting point... This results in the indium TIMs to melt again in subsequent packaging process... using metals like copper for enhanced thermal conductivity and high melting points to prevent re-melting

Methodology Applied

Scientific EffectMelting point resistance: Melting

Data Source

PatentUS20250062181A1Semiconductor Package With Thermal Conductive Structure and the Methods of Forming the Same

Publication Date: 2025.02.20 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes depositing a first metal layer on a package component, wherein the package component comprises a first device die, forming a dielectric layer on the package component, and plating a metal thermal interface material on the first metal layer. The dielectric layer includes portions on opposing sides of the metal thermal interface material. A heat sink is bonded on the metal thermal interface material. The heat sink includes a second metal layer physically joined to the metal thermal interface material.