Press-fit Pin Opening Geometry for Strain Reduction
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Solution Overview
Problem
Press-fit terminals face challenges in maintaining sufficient contact load while minimizing strain, which can lead to cracking due to stress concentration, especially in configurations with curved or narrow openings.
Innovation Solution
A press-fit terminal design featuring a elongated shape with a through hole formed by conductive portions, including pairs of linear and inclined linear portions that maintain a consistent width, reducing strain and enhancing contact reliability by distributing load effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the opening has curved ends with straight line portions extending close to the ends, then the terminal width decreases toward the tip end to facilitate insertion, but the width between the inner wall and tip end becomes small in wide regions, causing large strain and potential cracking
Solution Approach 1:
The opening shape is optimized with different characteristics at different locations: the curved ends facilitate insertion while the centrally located straight line portions maintain sufficient width to reduce strain. This local differentiation allows the terminal to have both easy insertion and high strain resistance.
Solution Approach 2:
The opening shape is pre-designed with curved ends that guide the terminal during insertion, and straight line portions that are positioned to maintain width before strain occurs. This preliminary geometric configuration prevents strain concentration before the terminal is fully inserted.
2Ease of operation
If the terminal has a configuration with small width around the ends of the opening, then insertion is facilitated, but large strain occurs around the ends when inserted into the through hole, causing cracking due to stress concentration
Solution Approach 1:
The opening geometry is designed with curved portions at the ends for easy insertion, while the straight line portions are positioned centrally to maintain sufficient width and prevent strain concentration. This local quality differentiation ensures both insertion ease and crack resistance.
3Reliability
If the terminal has a large contact load to the through hole, then stable electric contact is achieved, but large strain occurs in the terminal which may cause cracking
Solution Approach 1:
The opening shape parameters are optimized to achieve the right balance: the curved ends allow sufficient deformation for stable contact, while the centrally located straight line portions maintain width to limit strain magnitude, preventing cracking even under large contact loads.
Data Source
AI summary
A tip end and a base end therebetween define an opening located between a first conductive portion and a second conductive portion. The opening includes a pair of first linear portions, a pair of second linear portions, and a pair of third linear portions, which are located between the first conductive portion and the second conductive portion. The pair of first linear portions is in straight liner shapes and distant from both the tip end and the base end. The second linear portions are in straight liner shapes and located on the side of the tip end to have therebetween a distance decreasing toward the tip end. The third linear portions are in straight liner shapes and located on the side of the base end to have therebetween a distance decreasing toward the base end.