Alternating Polyimide Fluororesin Insulating Layer for PCB Warpage Control
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Solution Overview
Problem
Existing multilayer fluororesin films used in printed wiring boards struggle to achieve both good high-frequency properties and good bending properties.
Innovation Solution
A printed wiring board substrate is designed with an insulating layer composed of alternately stacked polyimide and fluororesin layers, with a specific thickness ratio and configuration that includes copper foils on both surfaces, optimizing the high-frequency and bending properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer fluororesin film with polyimide and fluororesin layers is used to achieve good high-frequency properties, then high-frequency performance is improved, but bending properties deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness ratio between polyimide layers and fluororesin layers. Specifically, the total thickness of polyimide layers is limited to 0.95 times or less of the total insulating layer thickness, while fluororesin layers constitute 5-20% of the total thickness. This quantitative parameter optimization resolves the contradiction by finding the optimal balance point where both high-frequency properties and bending properties are satisfied simultaneously.
Solution Approach 2:
The patent uses composite materials by combining polyimide layers and fluororesin layers in an alternating multilayer structure. This composite configuration leverages the complementary characteristics of both materials: polyimide provides mechanical strength and dimensional stability, while fluororesin provides low dielectric constant and good bending properties. The synergistic combination resolves the contradiction between high-frequency performance and bending properties.
2Reliability
If the total number of polyimide and fluororesin layers is increased to improve high-frequency properties, then high-frequency performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by establishing specific quantitative criteria for layer configuration. The total number of layers is constrained to 5 or more, with fluororesin layers comprising 5-20% of the total. These parameter specifications provide clear manufacturing guidelines that balance high-frequency performance requirements with manufacturing feasibility, avoiding excessive complexity while ensuring performance.
Data Source
AI summary
The printed wiring board substrate includes an insulating layer, a first copper foil, and a second copper foil. The insulating layer has a first main surface and a second main surface opposite to the first main surface. The insulating layer includes a plurality of polyimide layers and a plurality of fluororesin layers. The total number of the plurality of polyimide layers and the plurality of fluororesin layers is 5 or more. Each of the plurality of polyimide layers and each of the plurality of fluororesin layers are alternately stacked along a thickness direction of the insulating layer. One of the plurality of fluororesin layers constitutes a first outermost layer which is an outermost layer on the side of the first main surface. Another one of the plurality of fluororesin layers constitutes a second outermost layer which is an outermost layer on the side of the second main surface.