Encapsulated Power Module Bond Layer for Leak-Tight Cooling

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Solution Overview

Problem

Existing power semiconductor modules face challenges in achieving reliable leak-tight seals and high thermal conductivity without risking damage or delamination when integrated into cooling units, particularly in automotive applications.

Innovation Solution

A power module design featuring a semiconductor chip on a substrate with a bond layer encapsulated by a mold compound, a base plate with cooling structures, and micro channels, along with a lead frame for external contact, ensuring mechanical stability and effective heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the power semiconductor modules are mounted on a closed cooler with high thermal conductivity, then the thermal conductivity is improved, but the process temperatures required cause damage and/or delamination of the casing

Engineering Contradiction:

Improvethermal conductivityVSAvoidcasing integrity

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The patent introduces a mold compound as an intermediary material between the power semiconductor modules and the cooling unit. This mold compound enables reliable thermal coupling without requiring elevated process temperatures that would damage the casing, thus resolving the contradiction between achieving high thermal conductivity and maintaining casing integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the process parameters by using a mold compound that cures at lower temperatures compared to traditional bonding methods. This allows thermal coupling to be achieved without subjecting the casing to damaging high temperatures, thereby preserving casing strength while still achieving effective heat dissipation

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the power semiconductor modules are mounted with screws and O-ring sealing, then the seal reliability is improved, but the thermal conductivity is reduced

Engineering Contradiction:

Improveseal reliabilityVSAvoidthermal conductivity

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent merges the sealing function and thermal coupling function into a single integrated solution using a mold compound. The mold compound simultaneously provides leak-tight sealing and high thermal conductivity, eliminating the need for separate O-ring sealing and thermal interface layers, thus resolving the contradiction between seal reliability and thermal conductivity

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If the bond layer is exposed, then the manufacturing process is simpler, but the reliability is reduced due to aging effects

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidbond layer durability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent uses a mold compound that encapsulates the bond layer, protecting it from environmental aging effects. The mold compound acts as a protective shell that seals the bond layer from moisture and oxygen, thereby enhancing long-term reliability without significantly complicating the manufacturing process

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The mold compound provides beforehand protection to the bond layer against aging effects such as oxidation and moisture ingress. By encapsulating the bond layer during the molding process, the patent preemptively shields it from environmental degradation, ensuring long-term reliability

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

The design reduces the risk of coolant leakage, enhances thermal cycling capability, and allows for high operation temperatures while maintaining structural integrity and efficient heat dissipation.

Implementation Method 1

Power semiconductor modules used, for example, in inverters of electric cars, typically have to be cooled by a cooling unit using a liquid coolant

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

the power semiconductor modules can be mounted on a closed cooler. This requires a reliable bond between the power modules and the cooling unit with high thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4214749B1Power module and method for producing a power module

Publication Date: 2026.01.28 HITACHI ENERGY LTD

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AI summary

A power module (1) is provided, comprising - at least one power semiconductor module (2) having at least one semiconductor chip (3) arranged on a substrate (4) comprising at least one electrical insulating layer, - a lead frame (8) arranged in electrical contact to the at least one semiconductor chip (3), - a base plate (9) comprising cooling structures (10), - a bond layer (11) connecting the power semiconductor module (2) and the base plate (9), and - a mold compound (12) arranged on the power semiconductor module (2), the bond layer (11) and the base plate (9), wherein - the bond layer (11) is encapsulated completely by the power semiconductor module (2), the base plate (9) and the mold compound (12), and - the lead frame (8) is arranged at least partially within the mold compound (12). Furthermore, a method for producing a power module (1) is provided.