Optical Transceiver Coupling via U-Shaped FPC and Support Member

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Solution Overview

Problem

Conventional coupling mechanisms between optical subassemblies and circuit boards using flexible printed circuit boards face challenges such as reduced high-frequency performance, mechanical stress-induced wiring breaks, difficulty in soldering due to tight spacing, and complexity in manufacturing and connecting arrayed lead pins.

Innovation Solution

A coupling mechanism using a U-shaped flexible printed circuit board that connects lead pins without via holes, with a support member to alleviate mechanical stress and improve thermal and electrical contact, allowing for easier soldering and enhanced reliability and productivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the FPC board is extended to be bent for coupling the OSA and circuit board, then the gap between OSA and circuit board can be adjusted, but the high frequency performance of the transceiver deteriorates

Engineering Contradiction:

Improvegap adjustment capabilityVSAvoidhigh frequency performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention extracts the bending function from the FPC board itself by introducing a dedicated support member that provides the mechanical support needed for bending. This allows the FPC board to maintain its flat, high-frequency-optimized structure while still achieving the necessary gap adjustment through the support member's deformation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The support member acts as an intermediary between the FPC board and the mechanical stress required for gap adjustment. It absorbs the mechanical stress and provides the bending capability without transmitting it to the FPC board's wiring patterns, thereby protecting the high-frequency signal paths

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If the FPC board is bent to align the OSA along the optical axis, then the positional alignment improves, but mechanical stress is induced at the contact point causing wiring pattern break

Engineering Contradiction:

Improvepositional alignmentVSAvoidwiring pattern integrity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The invention extracts the stress-bearing function from the FPC board's wiring patterns by introducing a support member. The support member is specifically designed to absorb mechanical stress at the contact point, allowing the FPC board to maintain its structural integrity and wiring pattern continuity while still achieving the necessary positional alignment

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The support member provides beforehand cushioning by being positioned to absorb mechanical stress before it can reach the FPC board's wiring patterns. This preventive measure protects the wiring patterns from breakage while enabling the necessary bending for alignment

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Volume of moving object

If the transceiver is miniaturized to reduce size, then the compactness improves, but the space between lead pins becomes smaller making soldering difficult

Engineering Contradiction:

Improvetransceiver sizeVSAvoidsoldering difficulty

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The invention utilizes the thickness dimension of the FPC board to create soldering access space. By positioning the FPC board to extend in the thickness direction, it provides sufficient clearance for soldering tools to access the lead pins from the side, enabling soldering in miniaturized transceivers where planar space is constrained

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The flexible FPC board serves as a thin film structure that can be positioned and shaped to provide necessary clearance for soldering operations. Its flexibility allows it to be configured in ways that create access pathways for soldering tools without adding significant volume to the miniaturized transceiver

Inventive Principle:

Principle #30Flexible shells and thin films

4Quantity of substance

If arrayed lead pins are used to provide numerous connections, then the connection density improves, but the manufacturing complexity and cost increase due to required pin expansion

Engineering Contradiction:

Improvenumber of connectionsVSAvoidmanufacturing complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The FPC board serves multiple functions: it provides the wiring patterns for connecting arrayed lead pins, acts as a mechanical support structure, and enables soldering access through its three-dimensional configuration. This multi-functionality eliminates the need for additional expansion mechanisms, simplifying the manufacturing process while maintaining high connection density

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7267553B2Optical transceiver using optical sub-assembly having multiple lead pins connected to the substrate by a flexible printed circuit

Publication Date: 2007.09.11 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

The present invention provides a coupling mechanism between the optical subassembly and the circuit board using the FPC board. The mechanism according to the present invention may release the mechanical stress induced in the root portion of the lead pin of the optical subassembly and shows a superior productivity. The optical assembly provides a plurality of lead pins arranged in at least two rows. The FPC board bent in the U-shape is put between rows and soldered to the lead pins in the pads thereof. One piece of the FPC board is extended to the circuit board and soldered thereto.