Printed Wiring Board Metal Post Recess Design
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Solution Overview
Problem
Existing printed wiring boards with conductor posts face reliability issues due to stress concentration and potential peeling between the protruding and embedded portions, especially when electronic components with different thermal expansion coefficients are mounted, leading to reduced connection reliability and increased risk of deformation and cracking.
Innovation Solution
A printed wiring board design featuring metal posts with a protruding portion and an embedded portion integrally formed within the resin insulating layer, where the protruding portion is connected via a via conductor to a conductor layer on the opposite surface, and the embedded portion is designed to reduce stress transmission and maintain connection reliability by having a specific height and thickness ratio, and a corrosion-resistant layer is applied to prevent insulation failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal post is formed with a protruding portion and embedded portion in existing printed wiring boards, then the connection reliability is improved, but stress concentration and peeling occur between the portions leading to reduced reliability
Solution Approach 1:
The patent changes the geometric parameters of the metal post by forming a recess at the boundary between the protruding and embedded portions. This recess reduces the thickness of the metal post at the stress concentration point, thereby reducing stress concentration and preventing peeling while maintaining connection reliability.
Solution Approach 2:
The recess formed in the metal post acts as a stress relief feature that cushions the stress concentration that would otherwise occur at the boundary between the protruding and embedded portions. This beforehand cushioning prevents peeling and maintains connection reliability under thermal expansion stress.
2Adaptability or versatility
If electronic components with different thermal expansion coefficients are mounted on the printed wiring board, then the functionality is improved, but deformation and cracking occur due to stress
Solution Approach 1:
The patent modifies the metal post structure by forming a recess that reduces its thickness at the boundary portion. This parameter change allows the metal post to flex and accommodate differential thermal expansion between components with different thermal expansion coefficients, preventing deformation and cracking while maintaining connection reliability.
3Object-affected harmful factors
If the resin insulating layer is made thick to provide insulation, then the insulation performance is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
Instead of making the entire resin insulating layer thick, the patent applies the thick resin layer only at specific locations where insulation is most critical, while maintaining a thinner overall profile. This partial application reduces manufacturing complexity and cost while maintaining adequate insulation performance.
Data Source
AI summary
A printed wiring board includes a resin insulating layer, a metal post formed in the resin insulating layer such that the metal post is protruding from a first surface of the resin insulating layer, a conductor layer formed on a second surface of the resin insulating layer on the opposite side with respect to the first surface of the resin insulating layer, and a via conductor formed in the resin insulating layer such that the via conductor is penetrating through the resin insulating layer and connecting the metal post and the conductor layer. The metal post has a protruding portion protruding from the first surface of the resin insulating layer and an embedded portion integrally formed with the protruding portion and embedded in the resin insulating layer.