Cement-Based Semiconductor Encapsulation for Thermal Stress

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Solution Overview

Problem

Existing semiconductor modules with organic encapsulating masses face issues with thermal expansion mismatch between ceramic substrates and encapsulating materials, leading to mechanical stress, delamination, and low thermal conductivity, which complicates high-power electronics applications.

Innovation Solution

Using a purely inorganic cement-based encapsulating mass with low thermal expansion and high thermal conductivity, incorporating aggregates like aluminum nitride and boron nitride, and integrating non-conductive fibers to manage mechanical stress, while ensuring good adhesion and heat dissipation through chemical bonding with metallic cooling elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If organic encapsulating masses are used to encapsulate semiconductor components, then the encapsulation provides good adhesion and flexibility, but the thermal expansion coefficient mismatch with ceramic substrates causes mechanical stress and delamination

Engineering Contradiction:

ImproveadhesionVSAvoidmechanical stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The patent changes the fundamental material parameter of the encapsulating mass from organic to inorganic (cement-based), which fundamentally alters the thermal expansion coefficient to match ceramic substrates, thereby resolving the stress problem while maintaining adhesion through chemical bonding

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite cement-based materials combining inorganic binders (calcium aluminate, calcium sulfate) with inorganic aggregates (aluminum oxide, aluminum nitride, boron nitride) to achieve both mechanical stress resistance and thermal conductivity, while maintaining adhesion to ceramic substrates

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If organic encapsulating masses are used, then the encapsulation is easy to process, but the thermal conductivity is very low and insufficient for high-power electronics

Engineering Contradiction:

Improveprocessing easeVSAvoidthermal conductivity

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent creates a composite cement-based encapsulating mass incorporating high thermal conductivity aggregates (aluminum oxide, aluminum nitride, boron nitride) within the cement matrix, achieving thermal conductivity suitable for high-power electronics while maintaining processability through controlled viscosity and setting characteristics

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent enhances local thermal conductivity properties by strategically selecting and distributing high thermal conductivity aggregates (aluminum nitride, boron nitride) within the cement-based matrix, creating regions of enhanced heat dissipation capability where needed

Inventive Principle:

Principle #3Local quality

3Stress or pressure

If fillers with low expansion are added to organic matrix, then the thermal expansion mismatch is reduced, but the viscosity decreases and processing becomes error-prone with shrink holes

Engineering Contradiction:

Improvethermal expansion mismatchVSAvoidfilling quality

Core Design Contradiction:

Stress or pressureVSManufacturing precision

Solution Approach 1:

The patent replaces the organic matrix system with an inorganic cement-based system that sets through chemical hydration rather than mechanical cooling, eliminating the shrinkage and viscosity problems associated with organic materials while maintaining low thermal expansion through inorganic aggregate selection

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Stress or pressure

If high filling content is used in organic encapsulating mass, then the thermal expansion coefficient is reduced, but the processing requires high temperature and pressure which is energy-consuming

Engineering Contradiction:

Improvethermal expansion coefficientVSAvoidprocessing energy

Core Design Contradiction:

Stress or pressureVSUse of energy by moving object

Solution Approach 1:

The patent changes the setting mechanism from thermal (organic polymerization requiring high temperature) to chemical (cement hydration occurring at ambient or moderate temperatures), dramatically reducing processing energy requirements while achieving low thermal expansion through inorganic material selection

Inventive Principle:

Principle #35Parameter changes

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 cement-based encapsulation enhances thermal conductivity, reduces mechanical stress, and maintains structural integrity under thermal cycling, making it suitable for high-power electronics with improved reliability and efficiency.

Implementation Method 1

the cement-based encapsulation enhances thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

reduces mechanical stress

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10685894B2Semi-conductor module with an encapsulating cement mass that covers a semi-conductor component

Publication Date: 2020.06.16 HERAEUS ELECTRONICS GMBH & CO KG

AI summary

A semi-conductor module with an encapsulating mass that covers a semi-conductor component, in which the encapsulating mass is cement.