Electrode Projection Reduces Solder Joint Tensile Stress
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Solution Overview
Problem
Semiconductor apparatuses experience warpage due to differing linear coefficients of expansion during temperature cycles, leading to tensile stress at solder joints, which can cause peeling and reliability issues.
Innovation Solution
The semiconductor apparatus includes electrodes with a projection on the tip surface that are pushed against the circuit pattern by the case, reducing tensile stress and maintaining solder thickness, thereby preventing peeling and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode is solder-jointed to the circuit pattern without additional stress-reduction measures, then the manufacturing process is simple, but tensile stress during temperature cycles causes solder peeling and reliability degradation
Solution Approach 1:
The projection is formed on the electrode tip surface before the soldering process. This preliminary structural modification enables the electrode to actively push against the circuit pattern during temperature cycles, creating compressive stress that counteracts tensile stress and prevents solder peeling, thereby improving reliability without adding complex assembly steps
Solution Approach 2:
The projection is localized at the tip surface of the electrode where it contacts the circuit pattern. This local structural modification concentrates the stress-reduction effect precisely at the solder joint interface, maintaining solder thickness and preventing peeling without requiring complex modifications to the entire electrode structure or assembly process
2Reliability
If the electrode is pushed against the circuit pattern by the case, then tensile stress is reduced, but the solder thickness decreases due to compression
Solution Approach 1:
The projection is formed on the electrode tip surface before assembly, with its height specifically designed to compensate for the compression that will occur during temperature cycles. This preliminary dimensional adjustment ensures that when the electrode is pushed against the circuit pattern, the projection maintains the solder thickness within acceptable ranges while still providing the necessary compressive stress to prevent peeling
Solution Approach 2:
The projection's height and shape parameters are optimized to balance two competing requirements: providing sufficient compressive force to counteract tensile stress during temperature cycles, while limiting the compression to maintain solder thickness. By adjusting these geometric parameters, the design achieves both stress reduction and thickness maintenance
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 reduces stress at solder joints, prevents peeling, and improves the reliability of the semiconductor apparatus by maintaining solder thickness and alleviating stress during temperature cycles.
Implementation Method 1
Warpage of a semiconductor apparatus occurs due to a difference in linear coefficients of expansion of components during a temperature cycle
Data Source
AI summary
A semiconductor apparatus includes: an insulating substrate including a circuit pattern; a semiconductor device mounted on the insulating substrate and electrically connected to the circuit pattern; a case storing the insulating substrate and the semiconductor device; and an electrode attached to the case, wherein a tip surface of the electrode is jointed to the circuit pattern with solder, the electrode is brought into contact with and pushed against the circuit pattern by the case, and a projection is provided on the tip surface.