Flexible Printed Circuit Board Support for SMT Deformation Control
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Solution Overview
Problem
Flexible printed circuit boards (FPCs) face issues during surface mounted technology (SMT) processes due to lack of support, leading to deformation such as bending and faulty mounting, and during reflow soldering due to thermal expansion, resulting in reduced yield.
Innovation Solution
The FPC design includes a substrate with a first conductive layer, a protective layer having an accommodation space, and a support body that overlaps with the device and non-device regions, enhancing structural strength and preventing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a flexible printed circuit board is used without additional support structures, then the device maintains flexibility and thinness, but the FPC deforms during SMT processes and reflow soldering due to lack of structural support
Solution Approach 1:
The support body is pre-formed and then integrated into the FPC structure during manufacturing. This preliminary preparation of the support component allows for easier assembly and reduces the complexity of the overall manufacturing process while ensuring the FPC has adequate structural support during critical processes like SMT and reflow soldering.
Solution Approach 2:
The FPC employs a composite structure combining a flexible substrate with a support body made of different material properties. The support body provides rigidity and dimensional stability where needed, while the substrate maintains flexibility in other areas, creating a composite structure that balances both requirements.
2Strength
If the FPC has uniform thickness throughout, then manufacturing is simplified, but the non-device region lacks sufficient support during thermal expansion in reflow soldering
Solution Approach 1:
The support body is strategically positioned to provide enhanced support specifically in the non-device region where thermal expansion occurs during reflow soldering. This localized reinforcement approach addresses the specific structural weakness without requiring uniform thickness enhancement across the entire FPC, thus maintaining manufacturing simplicity while improving local support strength.
3Strength
If the support body is made larger to ensure complete coverage of device and non-device regions, then structural support is improved, but the FPC thickness and overall device profile increase
Solution Approach 1:
The support body extends slightly beyond the minimum required coverage area to ensure complete support of both device and non-device regions during manufacturing processes. This partial excess in coverage area is strategically designed to prevent deformation without causing excessive increase in FPC thickness, achieving optimal support with minimal dimensional impact.
Data Source
AI summary
A flexible printed circuit board includes a substrate, a first conductive layer, a first protective layer and a support body. The substrate has a device region and a non-device region, and the device region is configured to be coupled to a chip. The first conductive layer is located on a side of the substrate. The first protective layer is located on a side of the first conductive layer away from the substrate. The first protective layer is provided therein with an accommodation space. The support body is located at least in the accommodation space. An orthographic projection of the support body on the substrate at least overlaps with at least one of the device region and the non-device region of the substrate.