Terminal Electrode Geometry for Solder Crack Resistance
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Solution Overview
Problem
The conventional electronic component packages face issues with solder cracks due to differences in thermal expansion coefficients between the package and the circuit substrate, leading to fatigue failure and electrical disconnection, especially in automotive applications with varying temperatures and shock exposure.
Innovation Solution
The electronic component package features a base with pair of terminal electrodes having symmetrical rectangular shapes, where each electrode's long side is more than half the length of the base's long side, ensuring a uniform bonding area and minimizing strain influence, and includes bumps to redirect crack development, preventing multiple-point cracking and maintaining electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electronic component package uses ceramic material and the circuit substrate uses glass epoxy material, then the manufacturing cost is reduced and fabrication is facilitated, but the difference in coefficients of thermal expansion causes stress in the solder that bonds the package and substrate, leading to cracks
Solution Approach 1:
The patent changes the geometric parameters of the terminal electrode, specifically making its long side length more than half the length of the long side of the bottom face and positioning it adjacent to the long side edge. This parameter optimization redistributes the thermal expansion stress more uniformly across the solder joint, preventing stress concentration at the periphery and reducing crack initiation while maintaining the cost-effective ceramic-to-glass-epoxy material combination
Solution Approach 2:
The patent employs asymmetric positioning of the terminal electrode relative to the base, where the electrode is placed adjacent to one long side edge rather than being centrally positioned or symmetrically distributed. This asymmetric configuration creates a more favorable stress distribution pattern under thermal cycling conditions, reducing the harmful effects of differential thermal expansion between ceramic package and glass epoxy substrate
2Manufacturing precision
If the terminal electrode is extended from the bottom face to the side surface through castellation, then the connection state confirmation is improved, but the stress concentration at the periphery edge increases, causing crack initiation
Solution Approach 1:
The patent modifies the terminal electrode geometry by extending its long side to be more than half the length of the base's long side and positioning it adjacent to the long side edge. This dimensional change reduces stress concentration at the periphery while maintaining adequate castellation for connection verification, optimizing both manufacturing inspection capability and thermal stress resistance
3Adaptability or versatility
If the electronic component package is mounted in automotive applications with severe environments, then the application versatility is improved, but the fatigue failure in the solder occurs due to thermal expansion difference in high and low temperature environments
Solution Approach 1:
The patent optimizes the terminal electrode dimensions and positioning parameters to create a more robust solder joint configuration that can withstand the severe thermal cycling conditions of automotive applications. By making the electrode long side more than half the base length and positioning it at the long side edge, the design achieves better thermal stress distribution, enabling reliable operation across the wide temperature ranges encountered in automotive environments
Data Source
AI summary
A base of an electronic component package holds an electronic component element. The base has a bottom face in a rectangular shape in plan view. The base includes a pair of terminal electrodes having a rectangular shape on the bottom face. The pair of terminal electrodes are to be bonded on an external circuit substrate with a conductive bonding material. The pair of terminal electrodes have mutually symmetrical shapes. Each of the terminal electrodes has a long side adjacent to or on an edge of a long side of the bottom face. The long side of each of the terminal electrodes is disposed parallel to the long side of the bottom face. The long side of each of the terminal electrodes has a length that is more than half a length of the long side of the bottom face.