Elastic Contact Projection Geometry for Stable DC Resistance

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Solution Overview

Problem

Contacts used for electromagnetic compatibility in electronic circuit boards experience increased DC resistance when used in high-temperature environments, leading to reduced effectiveness over time.

Innovation Solution

A contact with a projection portion having a specific dimensional ratio of 0.25 ≤ H/L ≤ 0.44, where H is the height and L is the length, is designed to suppress the increase in DC resistance, utilizing a beryllium copper base with a tin plating and reflow treatment, and an elastic contact portion that maintains electrical connectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the contact structure is optimized to reduce DC resistance, then electrical connectivity is improved, but the contact may become more sensitive to temperature effects

Engineering Contradiction:
ImproveDC resistance valueVSAvoidtemperature sensitivity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention applies different material properties to different parts of the contact structure. The base portion uses beryllium copper or phosphor bronze for structural stability and elastic recovery, while the projection portion is designed with specific dimensional ratios to optimize electrical contact. This local differentiation allows the contact to resist thermal effects while maintaining low DC resistance.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The contact utilizes composite construction with a base portion made of beryllium copper or phosphor bronze, which combines high electrical conductivity with excellent elastic properties and thermal stability. This material selection creates a composite structure that inherently resists temperature-induced resistance changes while maintaining low DC resistance values.

Inventive Principle:
Principle #40Composite materials

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 contact effectively maintains low DC resistance even after prolonged use in high-temperature environments, as confirmed by heat cycle tests demonstrating stable resistance values within optimal dimensions.

Implementation Method 1

an elastic contact portion (5) having a shape protruding from the base portion (3) in a direction parallel to the component mounting surface (101). The elastic contact portion (5) is configured to be movable in the direction parallel to the component mounting surface (101) as the elastic contact portion (5) is elastically deformed

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

utilizing a beryllium copper base with a tin plating and reflow treatment

Methodology Applied
Scientific EffectReflow treatment: Heat Treatment

Data Source

PatentEP3754788B1Contact and method of manufacturing same
Publication Date: 2024.03.13 KITAGAWA INDS
  • EP3754788B1 patent drawingFigure 1
  • EP3754788B1 patent drawingFigure 2A~2F
  • EP3754788B1 patent drawingFigure 3

AI summary

The present invention provides a contact capable of suppressing an increase in a DC resistance value for a long period and a method of manufacturing the same. The contact (1) includes a base portion (3) and an elastic contact portion (5). The elastic contact portion (5) includes a planar portion (24) configured in a planar shape; and a projection portion (28) that is disposed on one surface of the planar portion (24) and protrudes from the one surface. The elastic contact portion (5) is configured to come into pressed contact with the second surface (53) at the projection portion (28). The projection portion (28) is configured such that a dimensional ratio H/L of the height H to the length L satisfies 0.25 ≤ H/L ≤ 0.44, where H is a height in a direction perpendicular to the one surface and L is a length in a direction parallel to the one surface.