Flexible PCB Interconnects with Variable Thickness
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Solution Overview
Problem
Flexible printed circuit boards face challenges in achieving reduced electrical resistance and increased flexibility while maintaining space-savings, as increasing interconnect thickness compromises flexibility and mounting compatibility, and widening interconnects may not provide sufficient space-savings.
Innovation Solution
The flexible printed circuit board design incorporates interconnects with varying thicknesses along their length, where the average thickness of a second portion is greater than a first portion by a ratio of 1.5 to 50, achieved through electroplating processes using resist patterns to form laminated structures, allowing for reduced electrical resistance and improved flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of interconnects is increased to reduce electrical resistance, then the electrical resistance decreases, but the flexibility of the flexible printed circuit board deteriorates
Solution Approach 1:
The interconnect structure is designed with different thicknesses in different regions: a first interconnect with uniform thickness and a second interconnect with non-uniform thickness (thicker in some portions, thinner in others). This local variation in thickness allows the circuit to have low electrical resistance where needed while maintaining flexibility in other areas, resolving the contradiction between electrical performance and mechanical flexibility.
2Reliability
If the thickness of interconnects is increased to reduce electrical resistance, then the electrical resistance decreases, but the mountability and compatibility with connection components deteriorates
Solution Approach 1:
The patent employs interconnects with spatially varying thickness where thicker portions provide low electrical resistance for power transmission, while thinner portions maintain compatibility with connection components and mounting requirements. This localized thickness optimization allows the circuit to simultaneously achieve low electrical resistance and good mountability.
3Reliability
If the width of interconnects is increased to reduce electrical resistance, then the electrical resistance decreases, but the space-savings of the flexible printed circuit board deteriorates
Solution Approach 1:
Instead of increasing interconnect width to reduce electrical resistance, the patent varies the thickness (vertical dimension) of the interconnects. By controlling the thickness distribution - with thicker portions for low resistance and thinner portions for space efficiency - the patent achieves reduced electrical resistance without compromising the compact size and space-savings of the flexible printed circuit board.
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 design enhances flexibility, reduces electrical resistance, and achieves space-savings by optimizing interconnect thickness ratios, enabling better performance in compact electronic devices.
Implementation Method 1
forming one or more first plating bodies extending in the longitudinal direction by electroplating a first metallic material on a conductive underlayer of the base film by using a first resist pattern
Data Source
AI summary
A flexible printed circuit board includes a base film having an insulating property, and one or more interconnects laminated to at least one surface side of the base film. At least one of the one or more interconnects includes, in a longitudinal direction, a first portion and a second portion that is a portion other than the first portion, an average thickness of the second portion being greater than an average thickness of the first portion. A ratio of the average thickness of the second portion to the average thickness of the first portion is greater than or equal to 1.5 and less than or equal to 50.