Elastic Contact Terminal Structure to Prevent Metal Layer Cracks
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Solution Overview
Problem
Conventional elastic electric contact terminals suffer from longitudinal cracks in the metal layer when pressed repeatedly, leading to increased electrical resistance and potential short circuits, and face challenges in manufacturing due to non-conductive coating layers protruding convexly, which complicates adhesion and control of spaces between the core and coating.
Innovation Solution
The design features first and second cores with elastic conductive films adhered to their surfaces and outer surfaces, forming a structure that minimizes stress and prevents longitudinal cracks by allowing the conductive films to bend laterally when pressed, while also facilitating vacuum pickup and reflow soldering using solder cream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric contact terminal is pressed repeatedly from top to bottom, then electrical connection is maintained, but longitudinal cracks occur in the metal layer increasing electrical resistance
Solution Approach 1:
The metal layer is divided into multiple segments along its length, with each segment capable of independent deformation. When compression force is applied, the metal layer bends laterally in segments rather than developing longitudinal cracks, maintaining electrical conductivity while accommodating repeated pressing cycles
Solution Approach 2:
The metal layer is designed to be dynamically flexible rather than rigid, allowing it to bend and deform laterally in response to compression forces. This dynamic behavior enables the metal layer to absorb repeated pressing without crack formation, maintaining reliable electrical connection
2Strength
If solder is formed along the sidewall to improve soldering strength, then soldering strength increases, but cracks become more severe at the boundary between solder and metal layer
Solution Approach 1:
The solder is extracted from the sidewall region and repositioned to form solder balls only at the bottom surface of the electric contact terminal. This eliminates the problematic boundary between solder and metal layer on the sidewall where cracks previously occurred, while maintaining adequate soldering strength through bottom-surface solder joints
3Ease of manufacture
If the non-conductive coating layer protrudes convexly to form spaces, then adhesion control is improved, but manufacturing precision decreases due to sticking issues
Solution Approach 1:
The non-conductive coating layer is designed with locally varied properties: it adheres to the core in most regions but intentionally does not adhere in specific localized areas to form spaces. This local quality differentiation enables both adhesion control and precise space formation, allowing the coating to provide structural support where needed while creating controlled voids for electrical isolation
4Area of stationary object
If the polymer film with metal layer is adhered to the entire sidewall, then coverage is improved, but the pressing force and recovery rate are modified by the adhesive and polymer film
Solution Approach 1:
The polymer film and adhesive are extracted from the sidewall region and repositioned to cover only the top and bottom surfaces of the core. This removes the interfering adhesive layer from the sidewall, allowing the metal layer to respond purely to compression forces with accurate pressing force transmission and recovery rate, while maintaining adequate coverage at the critical contact surfaces
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 the occurrence of longitudinal cracks, maintains low electrical resistance, and allows for reliable connection of objects over the shortest distance with improved resilience and reduced material costs, while accommodating various compression forces and recovery rates.
Implementation Method 1
first and second cores arranged horizontally to be coupled to each other and having elasticity
Implementation Method 2
an adhesive layer interposed between the electrically conductive film and the core
Implementation Method 3
reflow soldering using solder cream
Data Source
AI summary
An elastic electric contact terminal having a structure capable of preventing cracks in the longitudinal direction of a metal layer as much as possible when pressed from top to bottom is disclosed. The electric contact terminal includes: first and second elastic cores each having an upper wall, a lower wall, and a sidewall connecting the upper wall and the lower wall, and having an opening formed on an opposite side of the sidewall; a heat-resistant polymer film that surrounds the upper wall, lower wall, and opening of each core, and is adhered to at least the upper and bottom surfaces of each core via an elastic adhesive; and a metal layer formed on the outer surface of the polymer film. On a side where the opening is formed, the metal layer of each core is adhered to each other through an adhesive layer.