Flexible Substrate Joint Layout for Moisture-Resistant Bus Bar Modules
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Solution Overview
Problem
Conventional flexible substrates face challenges in increasing moisture resistance at the joint between electronic components and conductor circuits without reducing manufacturing yield, as resin film thickness is difficult to control, leading to potential short circuits due to dew condensation.
Innovation Solution
A flexible substrate design featuring a conductor circuit on the lower surface of a base film with a coverlay that exposes specific joint regions, using a metal plate to surround the electronic component and connect to the bus bar, ensuring moisture resistance while maintaining manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin film is applied to cover the joint region to increase moisture resistance, then the moisture resistance of the joint is improved, but the manufacturing yield is reduced due to difficulty in controlling film thickness
Solution Approach 1:
The invention extracts the harmful factor (dew condensation water) by providing a drainage path through the coverlay opening. The joint region is exposed through the opening, allowing condensation water to drain away rather than accumulate and cause short circuits, thereby improving moisture resistance without requiring a resin film that would reduce manufacturing yield
Solution Approach 2:
The invention converts the potentially harmful opening (which could allow moisture ingress) into a beneficial feature by designing it with drainage capability. The opening allows condensation water to drain away from the joint region, transforming what could be a source of short circuits into a moisture evacuation pathway that protects the joint
2Productivity
If a thin resin film is formed to maintain manufacturing yield, then the manufacturing yield is improved, but dew condensation water may enter the joint causing short circuits
Solution Approach 1:
The invention removes the need for resin film application by extracting the harmful moisture through the coverlay opening. The drainage path allows condensation water to escape, providing moisture protection without requiring a thin resin film that would compromise manufacturing yield
Solution Approach 2:
The coverlay is segmented with an opening that specifically exposes the joint region while maintaining coverage over other areas. This segmentation allows the opening to serve as a drainage path for moisture evacuation, providing protection without requiring additional resin film layers
Data Source
AI summary
A flexible substrate includes an electronic component, a base film, a conductor circuit, and a coverlay. The electronic component has an electrode. The conductor circuit is formed on a second surface (lower side surface in a vertical direction) of the base film, and has a joint region to which the electrode is jointed using a joint material. The coverlay covers at least a part of a second surface (lower side surface in the vertical direction) of the conductor circuit, and has an opening exposing the joint region to the outside.