PCB Moisture Path Design for FPC Assembly Reliability
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Solution Overview
Problem
Moisture permeation between a printed circuit board (PCB) and a flexible printed circuit board (FPCB) during the assembly process can lead to burning issues due to the inability to easily remove moisture from the empty spaces between the pads, causing damage and potential short circuits.
Innovation Solution
A printed circuit board design with a path for moisture between connection pads and non-connection pads, where the non-connection pads are removed and the space is filled with a solder resist or moisture absorbent, allowing for effective moisture removal during the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pads are spaced apart to allow soldering process, then soldering can be performed properly, but empty spaces between pads allow moisture permeation and accumulation
Solution Approach 1:
The patent extracts the harmful function of the empty space between pads by removing the pad structure itself in certain regions. By creating non-connection pad forming regions where pads are intentionally omitted, the design eliminates the trap that would otherwise accumulate moisture, while still maintaining necessary spacing for soldering operations in connection pad regions.
Solution Approach 2:
The patent applies different pad configurations to different regions of the substrate. Connection pad forming regions maintain spaced pads for proper soldering, while non-connection pad forming regions eliminate pads entirely to prevent moisture accumulation. This local differentiation allows simultaneous optimization of both soldering quality and moisture resistance in different areas.
2Object-affected harmful factors
If moisture removal path is created between connection pads, then moisture can be removed effectively, but the structure becomes more complex
Solution Approach 1:
The patent merges the moisture removal function with the existing pad layout design. By strategically positioning non-connection pad forming regions along the edges and between connection pads, the design creates moisture egress paths that utilize the same structural elements (pad spacing and removal) already necessary for electrical connection, thereby achieving moisture removal without adding separate complex structures.
Solution Approach 2:
The patent enables the PCB structure to serve its own moisture removal needs through its geometric configuration. The spacing and removal of pads in non-connection regions naturally create channels that allow moisture to escape during assembly and operation, without requiring additional active moisture removal systems or complex external structures.
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 prevents moisture-related damage by allowing for the removal of moisture through the path, reducing the risk of burning and ensuring reliable electrical connections between the PCB and FPCB.
Implementation Method 1
A path for moisture is disposed between two adjacent connection pads of the plurality of connection pads
Implementation Method 2
A moisture absorbent disposed on the at least one of the pad forming regions on which no connection pad is disposed
Data Source
AI summary
A printed circuit board includes a substrate and a plurality of pad forming regions disposed thereon. The plurality of pad forming regions are spaced apart from each other by a predetermined distance. A plurality of connection pads are disposed on a portion of the plurality of pad forming regions. The plurality of connection pads are configured to transmit or receive a signal to an external device or from the external device. The printed circuit board includes a path configured for the transportation of moisture therein.