Printed Wiring Board Thick Middle Layer Warping
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Solution Overview
Problem
Existing multilayer buildup printed wiring boards face challenges in maintaining rigidity and efficient heat radiation, particularly as they become thinner, leading to warping and inadequate thermal conductivity.
Innovation Solution
A printed wiring board design featuring a multilayer core substrate with a thick middle conductive layer connected to end-surface through holes, which enhances rigidity and thermal conductivity by allowing efficient heat radiation through these holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the printed wiring board is made thinner, then the weight and size are reduced, but the rigidity decreases causing warping
Solution Approach 1:
The board is divided into multiple thin layers (first buildup layer, multilayer core substrate, second buildup layer) connected through end-surface through hole conductors. This segmentation allows each layer to remain thin while the overall structure maintains rigidity through the distributed connection points, preventing warping without increasing overall thickness.
Solution Approach 2:
The invention uses composite construction with multiple conductive layers (first conductive layer, middle conductive layer, second conductive layer) separated by insulation layers. The middle conductive layer acts as a structural reinforcement within the composite, providing rigidity to prevent warping while maintaining the thin overall profile of the board.
2Ease of manufacture
If conventional structures are used, then manufacturing is simple, but heat radiation capability is insufficient
Solution Approach 1:
The end-surface through hole conductors provide an additional thermal conduction pathway in the vertical/dimensional direction, extending from the first buildup layer through the core substrate to the second buildup layer. This dimensional extension of heat paths allows efficient heat radiation without complicating the manufacturing process, as the conductors are formed using standard PCB fabrication techniques.
3Strength
If the middle conductive layer thickness is increased, then rigidity and heat conduction improve, but manufacturing complexity increases
Solution Approach 1:
The middle conductive layer serves multiple functions simultaneously: it provides structural rigidity to prevent warping, acts as a thermal conduction path for heat radiation, and functions as an electrical conductive layer. This multi-functionality allows the layer to improve strength and heat conduction without requiring additional separate components or complex manufacturing steps, as it integrates all these functions into a single layer formed during standard PCB fabrication.
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 solution effectively suppresses warping and improves heat radiation capabilities, meeting the demand for thinner boards while maintaining structural integrity and thermal performance.
Implementation Method 1
the middle conductive layer is connected to the end-surface through-hole conductor and has a thickness which is greater than thicknesses of the first and second conductive layers
Data Source
AI summary
A printed wiring board includes a multilayer core substrate, a first buildup layer formed on the multilayer core substrate and including an interlayer insulation layer and a conductive layer, a second buildup layer formed on the multilayer core substrate and including an interlayer resin insulation layer and a conductive layer, and an end-surface through hole conductor formed on side surfaces of the first and second buildup layers and core substrate such that the through hole conductor connects the conductive layers of the first and second buildup layers. The core substrate includes a first conductive layer, a middle conductive layer, a second conductive layer, a first insulation layer between the first and middle conductive layers and a second insulation layer between the second and middle conductive layers, and the middle conductive layer is connected to the through-hole conductor and has thickness greater than thicknesses of the first and second conductive layers.