Flexible PCB with Embedded Electronic Element
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Solution Overview
Problem
The challenge in the smartphone industry is to develop printed circuit boards (PCBs) that are thinner and more miniaturized while maintaining performance, particularly for radio frequency PCBs, as existing technologies struggle to integrate rigid and flexible components effectively for reduced thickness and increased flexibility.
Innovation Solution
A printed circuit board design that integrates a rigid portion and a flexible portion, where the flexible portion includes a thermoplastic resin layer and a thermosetting resin layer, with a first electronic element embedded within the flexible portion and a cavity formed to accommodate it, allowing for flexible integration and mounting, and a coverlay on the outer side for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid insulating layer is used to maintain structural stability, then the PCB has good mechanical strength, but the PCB cannot be bent or flexed
Solution Approach 1:
The PCB is divided into two distinct regions: a rigid portion containing the rigid insulating layer for structural stability, and a flexible portion containing the flexible insulating layer for bendability. This segmentation allows each region to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the PCB are assigned different material properties: the rigid portion uses rigid insulating layers (e.g., epoxy resin with glass fiber) for strength, while the flexible portion uses flexible insulating layers (e.g., polyimide) for bendability. This local differentiation resolves the contradiction between overall strength and local flexibility.
2Device complexity
If electronic elements are mounted on the surface of the PCB, then the PCB structure remains simple, but the PCB thickness cannot be reduced
Solution Approach 1:
Electronic elements are embedded within cavities formed in the flexible insulating layer, rather than being mounted on the surface. This nesting approach integrates the elements within the PCB structure itself, reducing overall thickness while maintaining structural simplicity.
Solution Approach 2:
The mounting approach transitions from two-dimensional surface mounting to three-dimensional embedding within the PCB layers. Cavities are formed in the flexible insulating layer to accommodate electronic elements, allowing vertical integration that reduces the PCB's footprint and thickness.
3Length of stationary object
If the PCB is made thinner through fine-scaling, then the PCB achieves miniaturization, but the mechanical strength and reliability decrease
Solution Approach 1:
The flexible insulating layer is constructed as a composite of multiple layers including a base layer (e.g., polyimide) and a reinforcing layer (e.g., glass fiber mesh). This composite structure provides enhanced mechanical strength and reliability even as the overall PCB thickness is reduced through fine-scaling.
Solution Approach 2:
The material composition and structural parameters of the flexible insulating layer are optimized to maintain reliability at reduced thickness. By adjusting the weave pattern, fiber orientation, and layer configuration of the glass fiber mesh, the PCB achieves the necessary mechanical properties despite being thinner.
Data Source
AI summary
Provided is a printed circuit board including a laminate that is formed by vertically stacking a plurality of insulating layers including a rigid insulating layer, a flexible insulating layer having a first region in vertical contact with at least one of the plurality of insulating layers and a second region located on an outer side of the laminate, and a first electronic element embedded in the flexible insulating layer.