Socket Contact Compressive Stress Design
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Solution Overview
Problem
Small-size socket contacts face challenges in retaining blade-shaped male contacts on a print substrate during soldering, as they are prone to detachment due to increased friction and bending moments, especially when compared to pin contacts.
Innovation Solution
A socket contact design featuring a housing with pair of strip-shaped elastic arms that apply contact force in opposite directions, securely mounting the blade contact orthogonal to the arms' opening direction, making it difficult for the lead portions to detach from the print substrate by applying compressive stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a blade-shaped male contact is inserted into a small-size socket contact, then the friction resistance increases and bending moment on the lead increases, but this causes the lead to detach from the print substrate
Solution Approach 1:
The socket contact is divided into distinct functional segments: the elastic arms for clamping, the base portion for structural support, and the lead portion for electrical connection. This segmentation allows each part to be optimized independently - the elastic arms provide high clamping force while the base portion geometry is designed to minimize bending moments on the lead, resolving the contradiction between clamping power and attachment reliability
Solution Approach 2:
The patent changes the insertion direction from the conventional direction to a direction orthogonal to the elastic arms' opening direction. This dimensional change allows the blade contact to be inserted horizontally while the elastic arms open vertically, reducing the lever arm and bending moment on the lead portion, thus maintaining attachment reliability while preserving clamping power
2Productivity
If the socket contact is made small in size, then the mounting density increases, but the clamping power and spring resistance decrease
Solution Approach 1:
The patent changes the geometric parameters of the elastic arms, specifically making them strip-shaped with optimized thickness and length ratios. This parameter optimization allows the small-size socket contact to achieve sufficient spring resistance and clamping power despite the reduced overall size, enabling high mounting density without sacrificing mechanical performance
3Productivity
If SMT is used instead of through hole mounting, then the central pattern clearance is narrowed and mounting density is increased, but the lead becomes more prone to detachment
Solution Approach 1:
The patent applies preliminary anti-action by designing the base portion geometry to preemptively counteract the bending moments that would otherwise detach the lead during blade contact insertion. The base portion acts as a stress-distributing structure that prevents solder joint failure before it can occur, enabling reliable SMT mounting with high density
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
The design effectively prevents detachment of the socket contact from the print substrate by ensuring only compressive stress acts on the lead portions during insertion, maintaining secure attachment even with blade-shaped contacts.
Implementation Method 1
a pair of elastic arms having strip-shaped front end portions extending from one end portion of the base portion, and clamping the opposing contact
Data Source
AI summary
A socket contact of small-size is provided for which detachment at solder from the print substrate is difficult. In the contact 1, a face in the thickness direction 120 of a front end portion of a pair of elastic arms 12a and 12b faces toward the insertion opening 21. When a blade contact 3 is inserted into an insertion opening 21, it is possible to open front end portions of a pair of elastic arms 12a and 12b in opposing directions. The configuration is such that, by providing first to third press fit fragments 111, 112, and 113 on a base unit 11, the same is securely held to the housing 2, so that only compressive stress acts on the pair of lead portions 11c and 11d, and can be made difficult to detach at solder from the print substrate 1p.