Printed Wiring Board Insulation Layer Segmentation for Warping Control
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Solution Overview
Problem
Existing printed wiring boards face challenges in achieving sufficient rigidity and preventing warping, especially when the core substrate thickness is reduced, while maintaining reliable electrical connections and thermal stress management.
Innovation Solution
A printed wiring board design featuring a core substrate with alternating conductive patterns and insulation layers, where the first insulation layer includes a reinforcing fiber material on the core substrate side and a second layer made of insulating material on the outer side, with a via conductor connecting the patterns, and a thinner second insulation layer formed using the same material as the second layer, enhancing rigidity and thermal stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the core substrate thickness is reduced to achieve thinner printed wiring boards, then the overall board thickness decreases, but the rigidity and warping resistance deteriorate
Solution Approach 1:
The first insulation layer is segmented into two distinct layers: a lower layer containing reinforcing fiber material for structural support, and an upper layer made of insulating material for electrical insulation. This segmentation allows each sub-layer to specialize in its function, maintaining rigidity while enabling overall board thinning.
Solution Approach 2:
The first insulation layer combines two different materials with complementary properties: reinforcing fiber material (for rigidity and warping resistance) and insulating material (for electrical insulation and compatibility with subsequent layers). This composite structure resolves the contradiction by integrating both mechanical strength and electrical functionality in a thin profile.
2Length of moving object
If the core substrate thickness is reduced, then the board becomes thinner, but warping resistance deteriorates
Solution Approach 1:
Dividing the first insulation layer into two functional layers allows the lower layer to specifically address warping resistance through reinforcing fibers while the upper layer maintains insulation properties, enabling thin board design without compromising stability.
Solution Approach 2:
The reinforcing fiber material is strategically positioned in the lower layer of the first insulation layer, precisely where structural support is most needed to prevent warping, while the upper layer provides uniform insulation. This localized quality distribution optimizes both thinness and warping resistance.
3Reliability
If different materials are used for the two layers of the first insulation layer, then functional requirements are met, but manufacturing complexity increases
Solution Approach 1:
The second layer of the first insulation layer and the second insulation layer are made of the same insulating material, creating homogeneity in the upper insulation regions. This material consistency simplifies the manufacturing process by allowing the same equipment and parameters to be used for both layers, reducing complexity while maintaining functional reliability.
Solution Approach 2:
The insulating material used in both the second layer of the first insulation layer and the second insulation layer serves multiple functions: electrical insulation, structural continuity, and process compatibility. This universal material selection reduces manufacturing complexity by enabling a unified processing approach for different functional layers.
Data Source
AI summary
A printed wiring board includes a core substrate, a first conductive pattern formed on the substrate, an insulation structure having a first insulation layer and formed on the substrate such that the first insulation layer covers the first pattern, a second conductive pattern formed on the structure, and a second insulation layer formed on the structure such that the second insulation layer covers the second pattern. The structure has a via conductor connecting the first and second patterns through the first insulation layer, the first insulation layer includes a first layer containing a reinforcing fiber material and a second layer formed on the first layer such that the first layer is on the substrate side and a second layer is on the second insulation layer side, and the second layer is made of an insulating material which is the same material as an insulating material forming the second insulation layer.