Flexible Rigid PCB Coverlay Interface Protection
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Solution Overview
Problem
Existing printed circuit boards (PCBs) face challenges in efficiently utilizing internal space in miniaturized mobile devices due to the integration of rigid and flexible components, where the interface between these components is prone to foreign material introduction and lacks effective protection.
Innovation Solution
A printed circuit board design featuring a flexible insulating layer, a laminated rigid insulating layer, and a coverlay with an adhesion layer, where the coverlay is bonded to the upper and side surfaces of both layers, preventing foreign material introduction and eliminating the need for a solder resist layer, and includes circuits and vias that penetrate through the coverlay and adhesion layer for electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a rigid insulating layer and flexible insulating layer are laminated to create an RFPCB, then space utilization is improved, but the interface between layers becomes vulnerable to foreign material introduction
Solution Approach 1:
A coverlay layer is disposed over the laminated structure of rigid and flexible insulating layers, forming a protective thin film that seals the interface between layers. This coverlay prevents foreign materials from penetrating into the interface while maintaining the thin-profile and space-efficient design of the RFPCB.
Solution Approach 2:
The patent employs a composite structure consisting of multiple materials: rigid insulating layer, flexible insulating layer, and coverlay layer. This composite construction combines the structural support of rigid material with the flexibility of flexible material, while the coverlay provides protective sealing against foreign material ingress at the interfaces.
2Ease of manufacture
If traditional PCB structures are used with separate solder resist layers, then manufacturing is standardized, but the number of layers and complexity increases
Solution Approach 1:
The coverlay layer serves multiple functions simultaneously: it acts as a protective barrier against foreign materials, provides solder resist functionality to prevent solder bridging, and serves as a structural layer in the laminated construction. By merging these functions into a single layer, the patent reduces the total number of layers compared to traditional PCB structures that would require separate solder resist and protective layers.
Solution Approach 2:
The coverlay layer is designed to perform multiple roles: mechanical protection of the interface, electrical insulation, solder resist functionality, and structural support. This multi-functional design eliminates the need for separate dedicated layers for each function, thereby reducing overall device complexity while maintaining ease of manufacture through standardized multi-layer lamination processes.
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 enhances the protection of the interface between rigid and flexible components, prevents foreign material ingress, and simplifies the manufacturing process by omitting the solder resist application, while maintaining electrical connectivity through the vias.
Implementation Method 1
The coverlay may adhere to the upper surface of the rigid insulating layer, the upper surface of the flexible insulating layer, and the side surface of the rigid insulating layer by an adhesion layer.
Data Source
AI summary
A printed circuit board, comprising a flexible insulating layer, a rigid insulating layer laminated on a portion of the flexible insulating layer, and a coverlay disposed on an upper surface of the rigid insulating layer, an upper surface of the flexible insulating layer, and a side surface of the rigid insulating layer positioned between the upper surface of the rigid insulating layer and the upper surface of the flexible insulating layer.