Stacked PCB Interposer Assembly for Dynamic Bend Rigid-Flexes
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Solution Overview
Problem
Integrating high complexity components with high pin counts and fine pitch interconnects on rigid-flex PCBs for dynamic bending areas results in low fabrication yields and reduced flex life due to incompatible fabrication processes.
Innovation Solution
Utilizing stacked PCB assemblies and interposers to isolate complex components on a separate rigid PCB, allowing independent optimization of dynamic bending flexible PCBs using compatible fabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high complexity components with high pin counts and fine pitch interconnects are integrated on rigid-flex PCBs for dynamic bending areas, then device functionality is achieved, but fabrication yields decrease and flex life is reduced
Solution Approach 1:
The PCB assembly is segmented into multiple separate PCBs (rigid PCB for complex components and flexible PCB for bending areas) that are stacked and interconnected. This segmentation allows each PCB to be optimized for its specific function - the rigid PCB can accommodate high pin count components with fine pitch interconnects while the flexible PCB can be optimized for dynamic bending without compromising fabrication yields or flex life
Solution Approach 2:
A flexible PCB acts as an intermediary between the rigid PCB containing complex components and the dynamic bending area. This intermediary flexible PCB absorbs the mechanical stress of bending through its flexibility while maintaining electrical connectivity, thereby protecting the rigid PCB and its sensitive interconnects from damage during dynamic bending operations
2Reliability
If fabrication processes are optimized for dynamic bending, then flex durability is improved, but compatibility with high complexity components is lost
Solution Approach 1:
The fabrication process is segmented into separate processes for rigid PCBs and flexible PCBs. The rigid PCB undergoes fabrication processes optimized for high complexity components with fine pitch interconnects, while the flexible PCB undergoes separate fabrication processes optimized for dynamic bending durability. This segmentation allows each PCB to be manufactured using the most appropriate processes for its specific requirements without compromise
Solution Approach 2:
Different fabrication qualities and processes are applied to different parts of the overall assembly. The rigid PCB receives high-precision fabrication processes suitable for fine pitch interconnects, while the flexible PCB receives fabrication processes optimized for flexibility and bend durability. Each local region receives the quality and process treatment it specifically needs
Data Source
AI summary
A stacked printed circuit board (PCB) assembly is provided comprising a first rigid PCB having high complexity components, a dynamic bending flexible PCB, and a PCB interposer electrically interconnected between the rigid and flexible PCBs. The high complexity components may have a pin count exceeding 100 and pitch under 0.4 mm. The dynamic bending flexible PCB is optimized for flexing by using fabrication processes unsuitable for the complexity components. The rigid and flexible PCBs are manufactured separately then integrated using the PCB interposer. This enables the rigid PCB to utilize processes for optimizing density and complexity without constraining the flexible PCB bending requirements. The discrete approach improves fabrication and bend cycle yields compared to conventional rigid-flex solutions. Reliable dynamic flexing is achieved while integrating complex components requiring rigid PCB fabrication.