Flexible Printed Circuit Board Via Plating Method
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Solution Overview
Problem
Existing flexible printed circuit boards (FPCs) face reduced flexibility due to the formation of an extra plating layer on the outermost metal foil layer, which is necessary for electrical connections through plated holes.
Innovation Solution
A method involving laminating metal foil layers with intervening layers, adhering a covering film, defining holes through the substrate using etching or laser technology, and plating the inner walls of these holes with conductive material to form vias without creating an extra plating layer on the outermost metal foil layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plated holes are formed to electrically connect metal foil layers, then electrical connectivity is achieved, but an extra plating layer is formed on the outermost metal foil layer reducing flexibility
Solution Approach 1:
The patent applies local quality by differentiating the treatment of hole inner walls versus outermost surfaces. Plating is applied locally only to the inner walls of holes for electrical connectivity, while deliberately avoiding plating on the outermost surfaces of metal foil layers, thus maintaining flexibility where needed while achieving conductivity where required
Solution Approach 2:
The patent segments the plating process into distinct zones: plating is applied to hole inner walls for electrical connection purposes, while the outermost surfaces are excluded from plating. This segmentation allows the circuit board to have both conductive pathways and flexible surfaces in appropriate locations
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 method allows for electrical connectivity between metal foil layers while maintaining the flexibility of the FPCs by avoiding the formation of an extra plating layer on the outermost surface, enhancing the board's flexibility and performance.
Implementation Method 1
adhering a covering film to outermost surfaces of the substrate
Implementation Method 2
defining a hole in one side of the substrate through the covering film and at least two metal foil layers and the intervening layer between the at least two metal foil layers by etching or laser technology
Implementation Method 3
defining a hole in one side of the substrate through the covering film and at least two metal foil layers and the intervening layer between the at least two metal foil layers by etching or laser technology
Implementation Method 4
plating a portion of an inner wall of the hole with a conductive material to form a via to electrically connect the at least two metal foil layers
Data Source
AI summary
An exemplary method of making an FPC includes forming a substrate comprising metal foil layers interleaved with intervening layers by: (a) laminating intervening layers with metal foil layers; (b) adhering a covering film to outermost surfaces of the substrate; (c) defining a hole in one side of the substrate through the covering film and at least two metal foil layers and the intervening layer between the at least two metal foil layers by etching or laser technology; and (d) plating a portion of an inner wall of the hole with conductive material to form a via to electrically connect the at least two metal foil layers.