Power Semiconductor Module Package Sealing for Thermal-Stress Hermeticity
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Solution Overview
Problem
Existing power semiconductor module packaging technologies face challenges in preventing gross leaks due to separation between the adhesive layer and external terminal electrodes, particularly under thermal stress from environmental changes, and the complexity of the mounting process hinders prompt completion and hermeticity maintenance.
Innovation Solution
A package design featuring a heat sink plate, first and second frames with resin, and an adhesive layer with specific portions connecting the external terminal electrode and frames, along with a protruding portion to reduce void formation near the through hole, uses a thermosetting resin and metal joining layer to enhance hermeticity and thermal stress relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple adhesive layer structure is used, then manufacturing complexity is reduced, but hermeticity deteriorates due to separation between adhesive layer and external terminal electrode under thermal stress
Solution Approach 1:
The adhesive layer is segmented into multiple portions (first adhesive layer, second adhesive layer, third adhesive layer) with different functions. The first adhesive layer connects the external terminal electrode to the first frame, the second adhesive layer connects the external terminal electrode to the second frame, and the third adhesive layer connects these two adhesive layers within the through hole. This segmentation allows each portion to be optimized for its specific function, preventing separation under thermal stress while maintaining manufacturing feasibility.
Solution Approach 2:
Different portions of the adhesive layer are designed with different properties and positions. The first adhesive layer is positioned at the first end of the external terminal electrode, the second adhesive layer at the second end, and the third adhesive layer within the through hole connecting them. This local differentiation ensures that each region of the adhesive layer addresses specific stress and connection requirements, thereby maintaining hermeticity without requiring a uniformly complex structure throughout.
2Reliability
If the adhesive layer is extended to connect frames and external terminal electrode, then hermeticity is improved, but manufacturing precision requirements increase due to positioning constraints
Solution Approach 1:
The external terminal electrode is prepared with a through hole before the adhesive layers are applied. This preliminary preparation allows the adhesive layers to be positioned and connected within the pre-formed through hole structure, reducing positioning constraints during assembly. The through hole serves as a pre-established guide and container for the third adhesive layer, thereby maintaining hermeticity without requiring extremely high manufacturing precision.
3Temperature
If high thermal conductivity material (Cu) is used for heat sink plate, then thermal performance is improved, but coefficient of thermal expansion mismatch with ceramic frame increases causing rupture
Solution Approach 1:
The heat sink plate is constructed as a composite material structure consisting of a Cu-W-based composite metal plate. This composite structure combines the high thermal conductivity of copper with the appropriate coefficient of thermal expansion characteristics of tungsten, allowing the heat sink plate to simultaneously achieve excellent thermal performance and thermal expansion compatibility with the ceramic frame, preventing rupture under thermal stress.
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 effectively prevents gross leaks by securing the adhesive layer's positions and reducing void formation, ensuring hermeticity and thermal stability, allowing for prompt module completion and environmental resistance.
Implementation Method 1
an adhesive layer... includes a first portion connecting the external terminal electrode and the first frame to each other, a second portion connecting the external terminal electrode and the second frame to each other
Implementation Method 2
uses a thermosetting resin and metal joining layer to enhance hermeticity and thermal stress relief
Implementation Method 3
A heat sink plate... is made of metal
Data Source
AI summary
A first frame is supported by a heat sink plate, surrounds an unmounted region of the heat sink plate, contains a resin, and has a first surface. A second frame contains a resin, and has a second surface opposing the first surface. An external terminal electrode passes between the first surface and the second surface. An adhesive layer contains a resin, and includes a lower portion, an upper portion, and an intermediate portion. The lower portion connects the external terminal electrode and the first surface to each other. The upper portion connects the external terminal electrode and the second surface to each other. The intermediate portion is disposed within a through hole of the external terminal electrode, and connects the lower portion and the upper portion to each other.