Multilayer Wiring Substrate Warping Control via Symmetric Insulation
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Solution Overview
Problem
Multilayer wiring substrates without a core substrate are prone to warping due to insufficient strength and uneven stress distribution from insulating layers, which affects the precision and density of wiring patterns.
Innovation Solution
A multilayer wiring substrate design with a center wiring layer surrounded by symmetrically arranged insulating layers of equal or unequal thickness and material properties on both sides, incorporating reinforcement materials like glass cloth in inner layers to balance stresses and prevent warping, while varying via shapes and conductor distributions to maintain flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a core substrate is removed to reduce thickness and increase wiring density, then the substrate thickness is reduced and wiring patterns can be formed with high density, but the substrate strength is reduced and warping occurs
Solution Approach 1:
The patent uses composite materials by combining insulating layers with reinforcement materials (glass cloth, aramid nonwoven fabric, or liquid crystal polymer nonwoven fabric) to create a core substrate that provides both mechanical strength and electrical insulation. This allows the substrate to maintain high strength while achieving the desired thinness and high wiring density.
Solution Approach 2:
The patent segments the substrate structure into multiple functional layers: a core substrate providing mechanical support, insulating layers providing electrical isolation, and wiring layers providing electrical connections. This segmentation allows each layer to be optimized for its specific function, with the core substrate specifically designed to prevent warping while allowing thin overall thickness.
2Strength
If reinforcement materials are added to insulating layers to enhance substrate strength, then the substrate strength is improved and warping is suppressed, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the thickness of insulating layers on different sides of the core substrate. By adjusting the thickness parameter of inner insulating layers (first insulating layer thickness vs. second insulating layer thickness), the patent optimizes the balance between substrate strength and manufacturing simplicity, achieving warping suppression without excessive complexity.
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 balances stresses across the substrate, reducing warping and enabling high-density, precise wiring patterns by equalizing or unbalancing stresses as needed, thus enhancing the substrate's strength and planarity.
Implementation Method 1
the stresses caused due to the insulating layers are made equal on one side and the other side of the center wiring layer, and a warp of the substrate is suppressed
Implementation Method 2
the insulating layers on one side and the other side of the substrate contain conceptually the case of single layer and the case of plural layers respectively. The insulating layers located in symmetrical positions with respect to the center wiring layer may be formed of a resin material into which reinforcement is mixed
Data Source
AI summary
A multilayer wiring substrate includes a center wiring layer arranged in a center of the substrate in a thickness direction, and wiring layers stacked on one side of the center wiring layer and the other side of the center wiring layer via an insulating layer. The wiring layers on one side of the center wiring layer and the wiring layers on the other side are provided in a same layer number. The insulating layers on one side of the center wiring layer and the insulating layers on the other side are provided in a same layer number.