Prepreg Resin Composition for Printed Wiring Board Heat Resistance
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Solution Overview
Problem
Conventional printed wiring boards with thick insulating layers exhibit low heat resistance after moisture absorption, as the resin composing the insulating layer ruptures and swells due to moisture evaporation during soldering, leading to reliability issues in electric conductivity and mountability.
Innovation Solution
A prepreg comprising a woven cloth substrate and a semi-cured resin composition containing epoxy and phenol resins with naphthalene or biphenyl skeletons, a high molecular weight epoxy-modified acryl resin, and surface-treated inorganic fillers, which improves heat resistance by preventing resin swelling and enhancing moisture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the insulating layer is increased to reduce warpage, then rigidity is improved, but heat resistance after moisture absorption deteriorates due to resin swelling
Solution Approach 1:
The patent uses a composite resin composition containing multiple components: epoxy resin (A1), phenol resin (A2), high molecular weight polymer (B), and silane-treated inorganic filler (C). This composite structure prevents resin swelling while maintaining rigidity, resolving the contradiction between strength and heat resistance after moisture absorption
Solution Approach 2:
The patent specifies precise parameter ranges for the resin composition components, including the weight ratios of epoxy resin to phenol resin (0.3 to 2.0), the molecular weight of the high molecular weight polymer (200,000 to 850,000), and the particle size of inorganic fillers (0.1 to 10 μm). These parameter optimizations ensure the resin maintains dimensional stability and prevents swelling under thermal and moisture stress
2Reliability
If the insulating layer is heated by soldering, then electric conductivity is established, but moisture evaporation causes resin rupture and swelling
Solution Approach 1:
The patent incorporates a high molecular weight polymer (B) with specific molecular weight (200,000 to 850,000) and structure into the resin composition beforehand. This component acts as a cushioning agent that prevents resin rupture and swelling during subsequent soldering heating, while still allowing moisture evaporation to establish electric conductivity
3Ease of manufacture
If conventional resin composition is used, then manufacturing is simple, but heat resistance after moisture absorption is low
Solution Approach 1:
The patent optimizes the molecular weight parameter of the high molecular weight polymer (B) to be 200,000 to 850,000, which balances manufacturing ease with improved heat resistance. The silane-treated inorganic filler (C) with specific surface treatment also enhances heat resistance while maintaining compatibility with conventional manufacturing processes
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 significantly enhances the heat resistance of printed wiring boards after moisture absorption, reducing warpage and improving reliability in electric conductivity and mountability, even in thick insulating layers, by preventing resin swelling and ensuring even moisture distribution.
Implementation Method 1
a (C1) component which is a first inorganic filler whose surface is treated with a first silane coupling agent; and a (C2) component which is a second inorganic filler whose surface is treated with a second silane coupling agent
Data Source
AI summary
A prepreg including: a woven cloth substrate; and a semi-cured product of a resin composition. The resin composition contains: at least one of an (A1) component and an (A2) component, a (B) component; a (C1) component; and a (C2) component. The (A1) component is an epoxy resin having at least one of a naphthalene skeleton and a biphenyl skeleton. The (A2) component is a phenol resin having at least one of a naphthalene skeleton and a biphenyl skeleton. The (B) component is a high molecular weight polymer. The (C1) component is a first filler obtained by treating surfaces of a first inorganic filler with a first silane coupling agent represented by formula (c1). The (C2) component is a second filler obtained by treating surfaces of a second inorganic filler with a second silane coupling agent represented by formula (c2).