Embedded PCB Pad Coplanar Surface Treatment
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Solution Overview
Problem
The challenge is to reduce the thickness of printed circuit boards while maintaining reliability and reducing manufacturing costs, particularly in response to the demand for lightweight and miniaturized mobile devices.
Innovation Solution
The solution involves a printed circuit board design with a first insulating layer, embedded pads, and surface treatment layers, where the pads are embedded within the insulating layer to minimize thickness, and the surface treatment layers are optimized to be coplanar with the insulating layer, reducing the need for excessive material and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the thickness of the printed circuit board is reduced to meet lightweight and miniaturization requirements, then the weight and size of the device are reduced, but the reliability and manufacturing precision become more difficult to maintain
Solution Approach 1:
The pad is embedded within the insulating layer, creating a nested structure where the conductor pattern is contained inside the insulating material. This nesting approach allows the pad to be integrated into the substrate thickness rather than adding to it, enabling thin PCB design while maintaining reliable electrical connections through the embedded structure that protrudes minimally from the surface.
Solution Approach 2:
The pad structure transitions from a surface-mounted configuration to an embedded three-dimensional structure within the insulating layer. By utilizing the vertical dimension within the substrate thickness, the pad achieves both compact footprint and reliable connection capability without increasing the overall PCB thickness, thus resolving the contradiction between weight reduction and reliability maintenance.
2Ease of manufacture
If the thickness of the surface treatment layer is reduced to lower manufacturing costs, then manufacturing costs are reduced, but the manufacturing precision and reliability of the pad structure become compromised
Solution Approach 1:
The pad is formed and embedded into the insulating layer before the surface treatment layer is applied. This preliminary formation of the pad structure allows the surface treatment layer to be applied at a later stage with controlled thickness, ensuring that the pad achieves the required coplanarity with the PCB surface while the surface treatment layer provides necessary protective and electrical functions at optimal thickness.
Solution Approach 2:
The thickness parameter of the surface treatment layer is optimized by changing the timing of its application relative to pad formation. By applying the surface treatment layer after pad embedding, the required thickness can be minimized while still achieving proper pad coplanarity, thus reducing manufacturing costs without compromising precision or reliability.
Data Source
AI summary
A printed circuit board includes a first insulating layer, a first pad embedded in one surface side of the first insulating layer and having one surface exposed from one surface of the first insulating layer, and a first surface treatment layer disposed on the exposed one surface of the first pad. A boundary surface between the first pad and the first surface treatment layer is substantially coplanar with the one surface of the first insulating layer.