Wiring Board Core Interlayer Foil Thickness Gradient
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Solution Overview
Problem
Existing wiring boards face challenges in managing thermal stress and cracking due to the concentration of stress around the core, especially in multi-layered structures, which affects connection reliability and durability.
Innovation Solution
A wiring board design with a core insulation layer and interlayer insulation layers alternately laminated, where the metal foil thickness on the core insulation layer is greater than on the interlayer insulation layers, and plating thickness is adjusted to mitigate thermal stress and enhance connection reliability, with stacked conductors forming a filled-stack structure to distribute stress evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wiring board structures with uniform metal foil thickness are used, then manufacturing simplicity is maintained, but thermal stress concentration and cracking occur around the core
Solution Approach 1:
The patent applies local quality by making the metal foil thickness non-uniform across different regions of the wiring board. Specifically, the outer layer metal foil is designed to be thicker than the inner layer metal foil, creating a gradient thickness structure that locally adapts to stress distribution patterns and mitigates thermal stress concentration around the core region.
Solution Approach 2:
The patent implements parameter changes by varying the thickness parameter of the metal foil across different layers. The outer layer metal foil thickness is intentionally increased compared to the inner layer, transforming the uniform thickness parameter into a graduated parameter that better accommodates thermal expansion differences and reduces stress concentration.
2Adaptability or versatility
If multi-layered interlayer insulation layers are added to increase wiring capacity, then functionality is improved, but thermal stress concentration and cracking risk increase
Solution Approach 1:
The patent addresses thermal stress concentration in multi-layered structures by implementing local quality through varied metal foil thickness. The outer layer metal foil is made thicker to specifically counteract the stress concentration that occurs at the core region, while inner layers maintain thinner foil to preserve overall structural integrity and reduce total stress accumulation.
Solution Approach 2:
The patent employs composite material principles by creating a layered structure with alternating interlayer insulation layers and conductor layers of different metal foil thicknesses. This composite structure combines materials with different thermal and mechanical properties in a graduated arrangement, allowing each layer to contribute differently to stress distribution and thermal management.
3Reliability
If plating thickness is increased to enhance connection strength, then connection reliability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies local quality to plating thickness by concentrating thicker plating in the outer layer metal foil where stress concentration occurs, while using thinner plating in inner layers where stress is lower. This localized approach to plating thickness optimization enhances connection strength at critical regions without uniformly increasing plating complexity across the entire board.
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
The design effectively reduces thermal stress and cracking near the core, enhances connection reliability, and improves the durability of multi-layered wiring boards by distributing stress evenly across the layers.
Implementation Method 1
The connection conductor of the core insulation layer includes a plating filling the hole of the core insulation layer
Data Source
AI summary
A wiring board including a core insulation layer having a connection conductor formed in a hole of the core layer, and an interlayer insulation layer laminated on one side of the core layer. The conductor of the core layer includes plating filling the hole of the core layer. The interlayer layer has a connection conductor formed in a hole of the interlayer layer. The conductor of the interlayer layer includes plating filling the hole of the interlayer layer. The conductor of the interlayer layer is stacked on the conductor of the core insulation layer. The conductors of the core and interlayer layers have lands formed on the core and interlayer layers and including metal foils and plating on the foils. The foil of the land on the core layer has a thickness which is thicker than a thickness of the foil of the land on the interlayer layer.