Multilayer PCB Warp Thread Orientation for Conductor Position Accuracy
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Solution Overview
Problem
In multilayer printed wiring boards, conductor patterns on core substrates tend to deviate in position due to thermal expansion and differing thermal histories of insulating layers, leading to potential disconnection in via holes and reduced reliability in interlayer-coupling.
Innovation Solution
A multilayer printed wiring board structure is developed with a core substrate and alternating buildup layers, where glass cloths with specific warp and weft thread orientations are used to maintain dimensional stability and position accuracy, with the threads in adjacent layers being perpendicular to each other, ensuring isotropy and preventing conductor pattern deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional insulating layers are used in multilayer printed wiring boards, then manufacturing is simplified, but conductor patterns deviate in position due to thermal expansion and differing thermal histories
Solution Approach 1:
The patent changes the physical and chemical parameters of the insulating layers by specifying particular resin compositions (epoxy resin with specific glass fiber content, polyimide resin properties) and thermal expansion coefficients to match between core substrate and buildup layers, thereby reducing position deviation of conductor patterns during thermal processing
Solution Approach 2:
The patent employs composite material structures where the core substrate and buildup layers use different resin systems (epoxy vs. polyimide) with complementary properties, creating a multilayer composite that balances thermal expansion characteristics and mechanical properties to maintain conductor pattern position accuracy
2Stability of the object's composition
If glass cloths with specific thread orientations are used in all layers, then dimensional stability is improved, but manufacturing complexity increases due to perpendicular arrangement requirements
Solution Approach 1:
The patent introduces asymmetry in the glass cloth structure by making the warp thread width different from the weft thread width (warp threads narrower than weft threads), and arranging adjacent layers with perpendicular orientations, creating an isotropic composite structure that achieves dimensional stability in all directions while providing a systematic stacking pattern
Solution Approach 2:
The patent resolves the stacking complexity by transitioning from a single-plane arrangement to a three-dimensional isotropic structure where glass cloth fibers are oriented in multiple directions (0 degrees, 45 degrees, 90 degrees) across different layers, achieving dimensional stability in all spatial dimensions
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
This approach enhances the dimensional stability and position accuracy of conductor patterns, reducing the likelihood of disconnection in via holes and improving the reliability of interlayer-coupling, even in high-density multilayered structures.
Implementation Method 1
conductor patterns on core substrates tend to deviate in position due to thermal expansion and differing thermal histories of insulating layers
Implementation Method 2
ensuring isotropy and preventing conductor pattern deviation
Implementation Method 3
the fiber base material is used to suppress a change in dimension due to absorption moisture and temperature
Data Source
AI summary
A multilayer printed wiring board includes a core substrate, a first buildup layer, and a second buildup layer. The first buildup layer includes a first insulating layer and a first conductor layer alternately laminated with each other. The second buildup layer includes a second insulating layer and a second conductor layer alternately laminated with each other. The core substrate, the first insulating layer, and the second insulating layer each include a glass cloth. The glass cloth is woven with warp threads and weft threads. The warp threads each have a width narrower a width of each of the weft threads. Each of the warp threads constituting the glass cloth in the first insulating layer and the second insulating layer both lying adjacent to the core substrate is arranged perpendicular to each of the warp threads constituting the glass cloth in the core substrate.