Semiconductor Module Ceramic Substrate Warpage Suppression
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Solution Overview
Problem
Conventional semiconductor modules face challenges with warpage of ceramic substrates due to thermal expansion differences, leading to reduced radiation efficiency and weight issues when attempting to omit metal plates for weight reduction.
Innovation Solution
A power semiconductor module design featuring metal layers on both surfaces of the ceramic substrate, with a groove pattern on the radiation surface to accommodate any resin intrusion and prevent it from reaching the inner pattern, ensuring uniform thermal expansion and maintaining radiation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metal plate is used to bond the ceramic substrate to prevent warpage and ensure good radiation characteristic, then the radiation efficiency is improved, but the weight of the semiconductor module increases
Solution Approach 1:
The patent applies local quality by forming a metal layer only on the radiation surface of the ceramic substrate where thermal contact is needed, rather than using a complete metal plate. This localized metal coating provides the necessary thermal conduction properties while significantly reducing the overall weight compared to a full metal plate construction.
Solution Approach 2:
The patent uses composite materials by combining ceramic substrate with a metal layer formed on its surface. This composite structure leverages the advantages of both materials: the ceramic provides mechanical strength and electrical insulation, while the metal layer provides thermal conduction, achieving effective heat radiation without the weight of a solid metal plate.
2Ease of manufacture
If resin is injected onto the chip mounting surface of the ceramic substrate without use of protecting material such as silicone gel, then the manufacturing process is simplified, but moisture may intrude from gap of the case and adversely influence the chip parts
Solution Approach 1:
The patent extracts and removes the silicone gel protecting material from the module structure, simplifying the manufacturing process by eliminating the step of injecting and sealing with silicone gel. The design accepts direct resin injection onto the chip mounting surface without the intermediate protective layer.
Solution Approach 2:
The patent provides beforehand cushioning by forming a groove on the radiation surface of the ceramic substrate that extends to the metal layer. This groove acts as a barrier that prevents resin from flowing onto the chip mounting surface during injection, thereby protecting the chip parts from resin contamination while allowing direct resin injection without silicone gel.
3Temperature
If resin is injected with the back surface of the ceramic substrate being in close contact with a flat inner surface of a mold to prevent resin from flowing onto the metal layer, then radiation efficiency is maintained, but a small amount of resin may still intrude onto the metal layer and attach onto it, significantly reducing radiation efficiency
Solution Approach 1:
The patent applies preliminary anti-action by pre-forming a groove on the radiation surface that extends to the metal layer before resin injection. This groove creates a physical barrier that prevents resin from reaching and attaching to the metal layer, countering the potential harmful effect of resin intrusion before it can occur during the injection process.
Solution Approach 2:
The patent segments the radiation surface by creating a groove that divides the surface into distinct regions: an inner region with the metal layer for heat radiation and an outer region that can accommodate resin without affecting radiation efficiency. This segmentation allows resin to be present in the module without compromising the thermal performance.
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 suppresses warpage of the ceramic substrate and prevents a reduction in radiation efficiency by ensuring uniform thermal expansion and accommodating resin intrusion within the groove pattern, enhancing the module's thermal cycle resistance and efficiency.
Implementation Method 1
to prevent the warpage of the ceramic substrate as much as possible, by forming not only on a surface of the ceramic substrate a metal layer for mounting a semiconductor chip, but also a metal layer on a back surface of the ceramic substrate, which is brought into abutting contact with the radiator, a thermal expansion characteristic of the both surfaces of the ceramic substrate are made uniform
Implementation Method 2
heat is radiated from a back surface of the ceramic substrate
Data Source
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AI summary
[Object] To suppress warpage of a ceramic substrate, and to prevent a reduction in radiation efficiency. [Means for Settlement] A power semiconductor module includes a module casing fitted with a radiator, and a common unit retained by the module casing. The common unit has: a ceramic substrate having a circuit surface disposed with a semiconductor element, and a radiation surface brought into abutting contact with the radiator; and a package formed by exposing the radiation surface and sealing the circuit surface with heat resistant resin. The circuit surface and the radiation surface are respectively formed of metal layers 51 formed on the ceramic substrate, and the metal layer 51 forming the radiation surface has: by forming a buffer pattern 512 including a groove part extending along a circumferential part thereof, a radiation pattern 510 formed on an inner side of the buffer pattern 512; and an outer peripheral pattern 511 formed on an outer side of the buffer pattern 512. Such a configuration enables warpage of the ceramic substrate to be suppressed, and a reduction in radiation efficiency to be prevented.