Folded FPC Optical Module for Crosstalk and Soldering
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Solution Overview
Problem
Miniaturization of optical modules leads to increased crosstalk between RF pins and degrades workability in the soldering process due to the need for precise spacing and potential short-circuits between DC pins on the Flexible Printed Circuit (FPC).
Innovation Solution
The optical module employs a folded FPC with distinct planar parts and land parts to prevent short-circuits and crosstalk, allowing for easier soldering and reduced stress on the FPC, while maintaining the necessary spacing for RF pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distances between DC pins are shortened to miniaturize the optical module, then the size of the electrical interface is reduced, but the risk of short-circuits between adjacently-positioned land parts increases
Solution Approach 1:
The FPC is folded along a fold line to create a three-dimensional configuration where land parts that would otherwise be adjacent in the planar direction are separated in the vertical direction. This dimensional transformation allows the DC pins to be positioned closer together horizontally while maintaining adequate isolation through the fold, thereby miniaturizing the optical module without increasing short-circuit risk
Solution Approach 2:
The FPC is divided into multiple planar parts separated by fold lines, creating distinct segments that can be positioned at different heights. This segmentation allows adjacently-positioned land parts to be physically separated in the vertical dimension, preventing solder bridges while maintaining compact horizontal spacing
2Object-generated harmful factors
If cut-out parts are formed in the FPC to separate adjacently-positioned land parts in the height direction, then crosstalk between DC pins is inhibited, but the workability in the soldering process is degraded
Solution Approach 1:
Instead of removing material (cut-outs) to achieve vertical separation, the patent uses folding to create height differences. This preserves the continuity of the FPC substrate, maintaining good soldering workability while still achieving the necessary isolation between land parts to prevent crosstalk
3Quantity of substance
If the DC pins are arranged in a row in the width direction on the FPC, then the number of pins can be accommodated, but the land parts positioned adjacent to each other may have short-circuits caused by solder
Solution Approach 1:
The FPC is folded to create vertical separation between land parts that are horizontally adjacent in the pin arrangement. This allows a high density of DC pins to be arranged in a row while the fold creates height differences that prevent solder bridges, thus accommodating more pins without compromising reliability
Data Source
AI summary
An optical module includes a substrate and terminals. The substrate has: a first planar part having first through holes into which the terminals are inserted respectively; a second planar part that opposes the first planar part as a result of the substrate being folded and has second through holes into which the terminals are inserted respectively; at least one first land part that is formed on the first planar part around at least one of the first through holes and that is connected to at least one of the terminals inserted through the first through hole; and at least one second land part that is formed on the second planar part around at least one of the second through holes into which another one of the terminals not being connected to the first land part is inserted and that is connected to the terminal inserted through the second through hole.