Flexible Circuit Board Via Layout for Misalignment Tolerance
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Solution Overview
Problem
The alignment misalignment of vias on flexible circuit boards can lead to short-circuiting, reducing the reliability of the circuit board.
Innovation Solution
The flexible circuit board design includes a substrate with circuit patterns on both surfaces connected by vias, where the vias have specific spacings and curved surfaces to prevent misalignment and short-circuiting, enhancing electrical connection characteristics and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vias are closely spaced to increase circuit density, then productivity and device integration are improved, but alignment precision deteriorates leading to short-circuits
Solution Approach 1:
The patent introduces a via land as an intermediary element between the via hole and the wiring part. This via land acts as a buffer zone that compensates for alignment variations, preventing short-circuits even when vias are closely spaced. The via land provides a larger target area for via placement while maintaining safe distances from adjacent conductive elements.
Solution Approach 2:
The via land is formed in advance before the via hole is created. This preliminary formation of the via land establishes a predefined safe zone that guides subsequent via placement, ensuring that even with alignment variations, the via will not short-circuit with adjacent wiring parts or via holes.
2Manufacturing precision
If via size is increased to improve alignment tolerance, then manufacturing precision is improved, but the area occupied by via increases reducing circuit density
Solution Approach 1:
The via structure is segmented into two distinct components: the via hole (conductive element) and the via land (isolation element). This segmentation allows the via land to provide alignment tolerance benefits without requiring the via hole itself to be larger, thus maintaining high circuit density while improving alignment tolerance.
Solution Approach 2:
The via land serves as an intermediary structure that provides the necessary alignment tolerance buffer without occupying excessive area. By separating the conductive function (via hole) from the alignment compensation function (via land), the design achieves tolerance without proportionally increasing total via structure area.
Data Source
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AI summary
A flexible circuit board according to an embodiment includes a substrate including a first surface and a second surface opposite to the first surface; a first circuit pattern disposed on the first surface; a second circuit pattern disposed on the first surface and the second surface; and a third circuit pattern disposed on the first surface and the second surface, wherein the second circuit pattern includes a first via and a second wiring part, wherein the third circuit pattern includes a second via and a third wiring part, wherein the first via and the second via includes a via land and a via hole formed in the via land, wherein at least one of the first via and the second via is defined as a first spacing between the via lands; a second spacing between the via land and the second wiring part or the third wiring part adjacent to the via land and a third spacing between a side surface of the via land and the via hole, and wherein at least one of the first spacing, the second spacing and the third spacing is greater than a width of the wiring part.