Zinc Oxide Filler Resin for PCB Layer Cracking
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Solution Overview
Problem
Preparation of multi-layered printed circuit boards faces issues such as bubbles in the resin, differences in junctional adhesion between layers leading to cracks, and poor solder resistance, with existing fillers like glass beads and foaming microspheres resulting in high production costs and drill wear due to high Mohs hardness.
Innovation Solution
A resin composition comprising an epoxy resin, a zinc oxide powder with a Mohs hardness of 4 to 5 and a diameter of 0.1 μm to 50 μm, and a hardener, where the zinc oxide powder is added in amounts from 0.5 to 10 parts by weight per 100 parts of epoxy resin, providing improved size stability, thermal resistance, and electrical properties while inhibiting cracking between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foaming microspheres are used as filler to improve electrical properties and heat resistance, then the laminate achieves better electrical properties and heat resistance, but the mass production cost increases and the Mohs hardness becomes too high causing rapid drill wear
Solution Approach 1:
The patent changes the key parameter of filler Mohs hardness by replacing foaming microspheres (high hardness) with zinc oxide powder (Mohs hardness 4-5). This parameter change maintains the electrical and thermal performance while dramatically reducing drill wear and manufacturing cost, as zinc oxide is softer and more compatible with drilling processes.
Solution Approach 2:
The patent adopts zinc oxide powder as a cost-effective alternative to expensive foaming microspheres. Zinc oxide is a cheaper, readily available material that provides comparable or superior performance in electrical and thermal properties without the high cost associated with processed foaming microspheres.
2Strength
If glass beads are used as spherical fillers to prevent board rupture, then the board resistance to bending improves, but the size stability and electrical properties deteriorate
Solution Approach 1:
The patent changes the filler material parameters by replacing glass beads with zinc oxide powder having specific characteristics (Mohs hardness 4-5, diameter 0.1-50 μm). This parameter change simultaneously improves size stability and electrical properties while maintaining crack inhibition capabilities, overcoming the limitations of glass beads.
Solution Approach 2:
The patent creates a composite resin system combining epoxy resin, hardener, and zinc oxide powder in specific proportions (0.5-10 parts zinc oxide per 100 parts epoxy resin). This composite formulation achieves optimal balance between mechanical strength, size stability, and electrical properties that neither glass beads nor pure resin can provide alone.
3Reliability
If multi-layered structure is used to provide stable circuit working environment, then the circuit stability improves, but bubbles in resin and junctional adhesion differences cause cracks and poor solder resistance
Solution Approach 1:
The patent uses zinc oxide powder with controlled particle size (0.1-50 μm) and specific hardness (Mohs 4-5) to create a homogeneous filler distribution throughout the resin. This homogeneity prevents bubble formation and ensures uniform junctional adhesion between layers, eliminating the cracking and solder resistance problems associated with multi-layered structures.
Data Source
AI summary
A resin composition is provided. The resin composition comprises an epoxy resin, a zinc oxide powder and a hardener, wherein the zinc oxide powder has a Mohs hardness ranging from about 4 to about 5 and a diameter ranging from about 0.1 μm to about 50 μm, and the amount of the zinc oxide powder is more than 0.5 parts by weight and less than 10 parts by weight per 100 parts by weight of the epoxy resin.