Flexible Circuit Board Side Pad Layout for Compact Optical Modules
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Solution Overview
Problem
The miniaturization of optical modules leads to increased electrical terminals and connection pads on flexible printed circuit boards (FPCs), causing widening of the board width, which complicates the connection and limits the compactness of the module.
Innovation Solution
The design incorporates side pads on the flexible printed circuit board, allowing for a reduced number of end pads in the width direction, with a recessed shape to maintain connectivity without expanding the board width, and includes a wiring pattern that connects end pads across regions for efficient signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of connection terminals on the FPC is increased to support multi-channel OSA, then the electrical connectivity is improved, but the lateral width of the FPC increases due to more connection pads
Solution Approach 1:
The patent transitions from a conventional single-row pad arrangement to a multi-dimensional pad layout by utilizing both end regions and side edges of the FPC base material. This spatial redistribution across multiple dimensions (end pads at both ends, side pads at lateral edges) increases connection terminal capacity without proportionally increasing the lateral width, as pads are distributed along the length direction as well as the width direction.
Solution Approach 2:
The connection terminals are segmented into distinct groups: end pads located at the first and second end regions, and side pads located at the side edges. This segmentation allows the pads to be distributed across different spatial zones of the FPC, optimizing the use of available space and reducing the concentration of pads in any single lateral region, thereby controlling the overall lateral width.
2Quantity of substance
If connection pads are disposed at the sides near connection pads at the end to maximize space utilization, then the connection density is improved, but the lateral width still increases due to the gap requirement between side pads and end pads
Solution Approach 1:
Instead of concentrating all pads in a single lateral row with minimal gaps, the patent utilizes the longitudinal dimension (length direction) by placing end pads at both the first end region and the second end region. This multi-dimensional distribution allows side pads to be positioned closer to end pads laterally without requiring large gaps, as the electrical connection path can extend along the length direction through the base material.
Solution Approach 2:
The patent applies different pad configurations to different local regions of the FPC: end pads are concentrated at the end regions for high-density connections at the OSA interface, while side pads are positioned at the side edges for connections along the lateral boundary. This localized optimization allows each region to serve its specific connection function efficiently without forcing uniform pad spacing across the entire FPC width.
Data Source
AI summary
A base material includes a pair of end regions located on both sides in a first direction, and an intermediate region located between the pair of end regions. The intermediate region includes a pair of side edges on both sides in a second direction orthogonal to the first direction. Both the pair of side edges do not project outward in the second direction from the pair of end regions. At least one of the pair of side edges has a shape recessed inward in the second direction from the pair of end regions. Terminals include end pads and a side pad. The end pads are located in each of the pair of end regions of the base material and arranged in the second direction. The side pad is located at at least one of the pair of side edges of the base material.