Copper Block Solder Joint Layout for Thermal Stress Resistance
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Solution Overview
Problem
The stress from thermal expansion and contraction of the sealing resin during curing in semiconductor devices leads to solder peeling off from the copper block, especially in high temperature environments.
Innovation Solution
A semiconductor device design where the area bonded by the first solder on the copper block is larger than the area bonded by the second solder, with the second solder positioned closer to the sealing resin surface to distribute stress, and optionally incorporating a roughened surface or thin resin layer to enhance adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing resin is cured during the manufacturing process, then the semiconductor device can be sealed and protected, but the stress of thermal expansion and contraction becomes relatively large, causing the solder to peel off from the copper block
Solution Approach 1:
The copper block is designed with different surface areas for different bonding regions. The first surface area (bonded to copper pattern) is larger than the second surface area (bonded to electrode terminal), creating local quality differences that distribute stress unevenly to protect critical solder joints from peeling
Solution Approach 2:
The copper block is pre-formed with asymmetric surface areas before the bonding process. This preliminary design ensures that when the sealing resin cures and generates thermal stress, the stress is already distributed in a way that prevents solder peeling, rather than trying to compensate after the problem occurs
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
Suppresses solder peeling from the copper block by distributing stress effectively and enhancing adhesion, ensuring reliable bonding under high temperature conditions.
Implementation Method 1
the temperature difference from the temperature at the start of curing to the room temperature is large, so that the stress of thermal expansion and contraction of the sealing resin becomes relatively large
Data Source
AI summary
An object is to provide a technique for suppressing solder from peeling from a copper block. A copper block is bonded on a copper pattern via first solder and an electrode terminal is bonded on the copper block via second solder. The sealing resin covers the copper pattern, the first solder, the copper block, the second solder, the electrode terminal, and the semiconductor element. The area of the portion of the copper block bonded by the first solder is greater than the area of the portion of the copper block bonded by the second solder.