Laminated Printed Wiring Board with Exposed Mounting Area
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Solution Overview
Problem
Existing printed wiring boards face challenges in efficiently exposing mounting areas for electronic components and ensuring reliable connections for high-speed signal transmission while minimizing warpage and crack formation.
Innovation Solution
A printed wiring board design featuring a laminated structure with a first circuit substrate and a second circuit substrate, where the second substrate has a mounting area with pads and connection wires connected to through-hole conductors, and a manufacturing method involving metal posts, insulating layers, and a frame-shaped groove to form an opening for exposing the mounting area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer substrate structure is used, then the manufacturing process is simple, but the mounting area cannot be effectively exposed and high-speed signal transmission is compromised
Solution Approach 1:
The substrate is divided into two distinct circuit substrates (first and second circuit substrates) with different functions. The first circuit substrate provides through-hole conductors for high-speed signals, while the second circuit substrate provides the mounting area. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between signal transmission quality and structural simplicity.
Solution Approach 2:
The solution transitions from a single-layer to a multi-layer vertical structure. By stacking the first circuit substrate beneath the second circuit substrate and using through-hole conductors that extend vertically, the patent creates three-dimensional signal paths. This dimensional change enables high-speed signal transmission while maintaining an exposed mounting area on the top surface.
2Ease of operation
If the mounting area is exposed by removing substrate material, then component mounting is enabled, but warpage and crack formation occur
Solution Approach 1:
Instead of removing substrate material to expose the mounting area, the patent extracts the mounting area function to a separate second circuit substrate layer. The opening portion in the first circuit substrate exposes the pads on the second circuit substrate without compromising the structural integrity of either layer, as both remain as complete, intact substrates.
Solution Approach 2:
The patent uses a composite multi-layer structure where the first and second circuit substrates work together. The first substrate provides mechanical support and signal transmission paths, while the second substrate provides the mounting platform. This composite structure distributes mechanical stresses and prevents warpage and cracks that would occur in a single substrate with material removed.
3Reliability
If through-hole conductors are used for connections, then signal transmission is improved, but manufacturing complexity increases
Solution Approach 1:
The through-hole conductors are formed in the first circuit substrate before the second circuit substrate is attached. This preliminary formation of conductive paths allows for precise alignment and connection to pads on the second substrate, improving connection reliability while enabling standardized manufacturing processes.
Data Source
AI summary
A printed wiring board includes a first circuit substrate having a first surface and a second surface on the opposite side, and a second circuit substrate having a third surface and a fourth surface on the opposite side such that the first circuit substrate is laminated on the third surface and that the first surface and the third surface are opposing each other. The second circuit substrate has a mounting area on the third surface and includes pads positioned to mount an electronic component in the mounting area and a connection wire structure connected to the pads, and the first circuit substrate includes through-hole conductors extending from the first surface to the second surface and connected to the pads through the connection wire structure and has an opening portion formed through the first circuit substrate such that the opening portion is exposing the pads formed in the mounting area.