Optical Modulator FPC Cutouts for Stress Relief
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Solution Overview
Problem
In optical modulators using flexible printed circuits (FPCs), variations in signal path high-frequency characteristics due to deformation and stress issues during manufacturing and assembly lead to unsatisfactory optical transmission quality and increased manufacturing costs.
Innovation Solution
The optical modulator incorporates a flexible wiring board with cutouts or notches on its sides to relieve mechanical stress and prevent strain propagation, allowing for accurate pad positioning and reduced solder thickness variation, thereby stabilizing high-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If an FPC is used to connect lead pins to the circuit board, then the device size is reduced and mounting space is minimized, but mechanical stress and deformation occur during manufacturing and assembly, causing variation in high-frequency characteristics
Solution Approach 1:
The FPC is segmented by forming cutouts or notches that divide the continuous structure into sections. This segmentation allows different parts of the FPC to move independently, relieving mechanical stress while maintaining electrical connectivity through the via holes and lead pins.
Solution Approach 2:
The FPC is designed with non-uniform structure by adding cutouts or notches at specific locations. These local modifications create stress relief zones where the FPC can deform without affecting the overall connection, while areas with pads and via holes maintain their structural integrity for reliable electrical connection.
2Ease of manufacture
If the FPC is made flexible to accommodate assembly variations, then ease of assembly is improved, but strain propagation occurs during soldering, causing pad positioning errors and solder thickness variation
Solution Approach 1:
Material is extracted from the FPC by forming cutouts or notches. These removed sections act as isolation zones that prevent strain propagation from one area of the FPC to another, particularly preventing strain from traveling to the pad areas during soldering operations.
Solution Approach 2:
The cutouts or notches are pre-formed in the FPC to provide stress relief zones before assembly occurs. These zones act as cushions that absorb mechanical stress and strain during the soldering process, protecting the pad positioning and solder joint quality from deformation.
3Manufacturing precision
If cutouts or notches are added to the FPC to relieve stress, then high-frequency characteristics are stabilized, but the FPC structure becomes more complex
Solution Approach 1:
The FPC structure is segmented by adding cutouts or notches that divide the board into sections. This segmentation simplifies the stress management by creating natural isolation zones, making the overall system more robust despite the apparent increase in structural features.
Solution Approach 2:
The FPC utilizes its inherent flexibility as a thin film structure, and the cutouts or notches enhance this flexibility by creating compliant zones. This allows the FPC to accommodate assembly variations through controlled deformation rather than requiring rigid precision, simplifying the assembly process.
Data Source
AI summary
An optical modulator with FPC and optical transmission device using the same are provided. This optical modulator includes a flexible printed circuit which electrically connects the optical modulator to a circuit board. The flexible printed circuit has a substantially quadrilateral shape. A pad is formed on the flexible printed circuit along one side of the substantially quadrilateral shape so as to be electrically connected to the circuit board. In order to release the mechanical stress applied onto the side or the end portion of the flexible printed circuit and/or to prevent propagation of distortion generated in the side or the end portion, the flexible printed circuit has: a cutout or a notch provided in a direction from a part of at least one side toward the inside of the flexible printed circuit; and/or a curved portion connecting at least two adjacent sides.