Printed Wiring Board Warpage Control via Layered Insulation
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Solution Overview
Problem
Printed wiring boards with resin insulating layers face challenges in warpage and connection reliability due to differences in strength between reinforcing and non-reinforcing material layers, leading to potential issues with electronic component mounting and conductor layer thickness variability.
Innovation Solution
A printed wiring board design featuring alternating layers of resin insulating layers with and without reinforcing materials, where the conductor layers are formed with specific thickness and diameter configurations to balance strength and warpage, using metal foils, seed layers, and electrolytic plating films to ensure equal thickness and reliable connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If resin insulating layers with reinforcing materials are used, then strength is improved, but warpage increases due to strength differences between layers
Solution Approach 1:
The patent applies local quality by differentiating the structure of resin insulating layers based on their position. Outer resin insulating layers contain reinforcing materials for strength, while inner resin insulating layers exclude reinforcing materials to maintain flatness. This localized structural differentiation resolves the contradiction between overall strength enhancement and warpage prevention.
2Reliability
If conductor layers are formed on resin insulating layers with reinforcing materials, then connection reliability is improved, but thickness variability increases leading to manufacturing difficulties
Solution Approach 1:
The patent implements local quality by forming conductor layers only on specific resin insulating layers (outer layers with reinforcing materials) while leaving inner layers without conductor layers. This selective formation ensures that conductor layers achieve reliable connections on suitable substrates while avoiding the thickness variability and manufacturing issues that would arise from forming conductors on all layers, particularly on inner layers with reinforcing materials.
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 reduces warpage and enhances connection reliability by balancing the strength of reinforcing and non-reinforcing layers, allowing for reliable electronic component mounting and maintaining equal thickness across conductor layers, thus facilitating high-density circuit formation and impedance matching.
Implementation Method 1
a first electrolytic plating film on the first seed layer... and a second electrolytic plating film on the second seed layer
Data Source
AI summary
A printed wiring board includes a core substrate, a first build-up layer, and a second build-up layer. Each build-up layer includes a first insulating layer including reinforcing material, a second resin insulating layer not containing reinforcing material, a first via conductor through the first insulating layer, and a second via conductor through the second insulating layer such that the top diameter of the first via conductor is substantially equal to the top diameter of the second via conductor and that the bottom diameter of the first via conductor is smaller than the bottom diameter of the second via conductor. The conductor layer on the first insulating layer includes a metal foil, a seed layer and an electrolytic plating film. The conductor layer on the second insulating-layer includes a seed layer and an electrolytic plating film and has thickness substantially equal to thickness of the conductor layer on the first insulating-layer.