Semiconductor Device Strain-Reducing Metal Plate
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Solution Overview
Problem
In power modules, the reliability of soldered bonding parts between insulating substrates and heat-dissipating base plates is compromised due to repeated temperature changes and strain caused by differences in linear expansion coefficients, leading to breakage and degraded heat dissipation performance.
Innovation Solution
A semiconductor device structure featuring a wiring substrate, a metal plate for reducing strain between the wiring substrate and the heat-dissipating base plate, and a second bonding part with a thicker outer circumference than center, which reduces strain and enhances mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering is used to bond the wiring substrate and heat-dissipating base plate, then electrical connection and heat dissipation are achieved, but the bonding part is susceptible to breakage due to repeated temperature changes and strain from linear expansion coefficient differences
Solution Approach 1:
A metal plate for reducing strain is introduced as an intermediary component between the wiring substrate and the heat-dissipating base plate. This metal plate has a linear expansion coefficient that is intermediate between those of the wiring substrate and the base plate, thereby reducing the strain differential and preventing solder joint breakage while maintaining electrical and thermal connectivity.
2Ease of manufacture
If a uniform thickness metal plate is used for reducing strain, then manufacturing is simplified, but the outer circumferential part of the bonding part experiences excessive strain leading to breakage
Solution Approach 1:
The metal plate for reducing strain is designed with non-uniform thickness: the outer circumferential part has a greater thickness than the center part. This local variation in thickness provides enhanced strain reduction capability at the outer circumferential bonding parts where strain is most severe, while maintaining manufacturability through conventional forming processes.
3Strength
If lead-containing solder is used for high heat resistance bonding, then bonding strength and heat resistance are improved, but environmental burden increases
Solution Approach 1:
The invention converts the previously harmful effect of strain concentration in lead-free solder joints into a beneficial outcome by introducing the metal plate for reducing strain. This allows the use of environmentally friendly lead-free solder while achieving bonding reliability comparable to or exceeding that of lead-containing solder through the strain-reducing metal plate intermediary.
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
This configuration significantly reduces strain at the bonding part, preventing breakage and enhancing the reliability and heat dissipation performance of the semiconductor device.
Implementation Method 1
strain is repeatedly caused in the soldered bonding part by a difference in the linear expansion coefficient between the members
Implementation Method 2
heat dissipation performance is degraded
Data Source
AI summary
A semiconductor device is provided, the semiconductor device having: a semiconductor chip; a wiring substrate which supports the semiconductor chip and is electrically connected to the semiconductor chip; a first metal plate which supports the wiring substrate; a second metal plate which is arranged between the wiring substrate and the first metal plate; a first bonding part which bonds the wiring substrate and the second metal plate; and a second bonding part which bonds the first metal plate and the second metal plate, and having a thickness of an outer circumferential part of the second metal plate being larger than a thickness of a center part of the second metal plate.