Optical Module Ground Pin Structure for Flexible Circuit Routing
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Solution Overview
Problem
In optical modules with a ground pin fixed to the outer surface of a stem by welding, the fixing is often insufficient due to the pin's thinness, requiring enlarged holes in flexible printed circuits, which reduces the area for wiring and design freedom.
Innovation Solution
An optical module design featuring a stem with a through hole, a signal lead pin, a ground pin with a larger joint portion, and a flexible printed circuit with specific through holes for each, allowing the ground pin's diameter to match the pin portion without reducing wiring design freedom, using a metal plate for electrical and mechanical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ground pin is kept thin for welding to the outer surface of the stem, then the welding process can be simpler, but the fixing between the outer surface of the stem and the ground pin becomes insufficient
Solution Approach 1:
The ground pin is designed with different diameters at different locations: a smaller diameter pin portion for welding and a larger diameter joint portion for mechanical support. This local variation in geometry allows the thin pin to be welded easily while the enlarged joint portion provides sufficient fixing reliability.
2Ease of manufacture
If the hole diameter of the through hole in the flexible printed circuit is enlarged to match the welded part of the ground pin, then the ground pin can be properly installed, but the area available for wiring is reduced
Solution Approach 1:
The ground pin's joint portion has a larger diameter that matches the through hole in the flexible printed circuit, providing proper mechanical support and ease of installation. The pin portion has a smaller diameter that allows for adequate wiring space around the through hole, thus maintaining wiring design freedom.
3Volume of moving object
If the ground pin is made thin to maintain flexibility, then the overall module size can be reduced, but the electrical connection reliability may be compromised
Solution Approach 1:
The ground pin uses a thin pin portion for flexibility and small module size, while the joint portion is enlarged to provide reliable electrical connection and mechanical support. This localized thickening at the joint portion ensures connection reliability without compromising overall module compactness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design ensures secure electrical connections and maintains the flexibility in wiring design by matching the ground pin's diameter with the through hole size, preventing the need for enlarged holes and enhancing the module's frequency characteristics.
Implementation Method 1
a plate made of metal having a back surface joined to the outer flat surface of the stem and a front surface joined to the exposed surface of the ground pattern
Data Source
AI summary
An optical module includes: a stem made of metal; a ground pin including a pin portion and a joint portion having a diameter larger than a diameter of the pin portion and joined to an outer flat surface of the stem; a flexible printed circuit including a wiring pattern on a front surface and a ground pattern having an exposed surface at a position facing the outer flat surface of the stem on a back surface, in which a tip portion of the pin portion of the ground pin penetrating a second through hole is electrically connected to the second through hole on the front surface; and a plate made of metal, having a back surface joined to the outer flat surface of the stem and a front surface joined to the exposed surface of the ground pattern.