Thermosetting Resin Composition for Flexible PCBs
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Solution Overview
Problem
There is a need for sheet-type electronic materials that can be quickly processed and exhibit excellent electrical insulation reliability under severe conditions, such as high temperature and humidity stress, which existing materials fail to achieve efficiently.
Innovation Solution
A thermosetting resin composition comprising a solid epoxy resin, a non-solid epoxy resin, particulate rubber, a curing agent, an inorganic filler, and polycarbonate diol-derived polyurethane, with specific ratios and properties, is used to create a coverlay film, adhesive sheet, and flexible printed wiring board that can be quickly pressed and maintains excellent electrical insulation reliability in biased highly accelerated temperature and humidity stress tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional thermosetting resin compositions are used, then processing time is reduced for quick pressing, but electrical insulation reliability deteriorates under severe conditions
Solution Approach 1:
The patent uses a composite resin system combining epoxy resin with polyurethane resin and rubber particles. This composite formulation achieves both quick pressing capability and excellent BHAST resistance by integrating multiple material properties: epoxy provides structural integrity, polyurethane enables low-temperature curing for quick processing, and rubber particles maintain flexibility and electrical insulation under thermal stress.
Solution Approach 2:
The patent modifies the chemical composition parameters of the thermosetting resin by incorporating polyurethane resin with specific molecular weight (10,000-50,000) and acid value (10-30 mgKOH/g), along with rubber particles at controlled concentrations. These parameter changes enable the resin to cure rapidly at lower temperatures while maintaining electrical insulation properties under high temperature and humidity conditions.
2Productivity
If the resin composition is optimized for quick pressing, then processing efficiency is improved, but electrical insulation properties under high stress conditions worsen
Solution Approach 1:
The patent creates a multi-component composite system where epoxy resin provides fast curing kinetics for high productivity, polyurethane resin contributes flexibility and electrical insulation stability, and rubber particles enhance stress resistance. This composite approach allows simultaneous optimization of processing efficiency and electrical insulation reliability under BHAST conditions.
Solution Approach 2:
The patent carefully controls chemical parameters including polyurethane resin molecular weight (10,000-50,000), acid value (10-30 mgKOH/g), and rubber particle content (5-20 parts by mass per 100 parts epoxy resin). These parameter optimizations enable rapid curing for high productivity while ensuring electrical insulation properties remain stable under high temperature and humidity stress.
3Loss of time
If polycarbonate diol-derived polyurethane with specific properties is used, then quick pressing capability is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies precise parameters for polycarbonate diol-derived polyurethane: molecular weight of 10,000-50,000 and acid value of 10-30 mgKOH/g. These parameter specifications enable the polyurethane to react efficiently with epoxy resin at lower temperatures, achieving quick pressing capability. The controlled parameters simplify manufacturing by providing clear material selection criteria rather than requiring complex process control.
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 proposed solution enables quick processing and maintains high electrical insulation reliability in severe conditions, ensuring effective performance in BHAST evaluations and providing excellent solder heat resistance and flame retardance.
Implementation Method 1
polycarbonate diol-derived polyurethane, wherein a content of the particulate rubber is from 3 to 15 parts by mass with respect to a total part by mass of the solid epoxy resin and the non-solid epoxy resin, an acid value of the polycarbonate diol-derived polyurethane is from 10 to 30 mgKOH/g
Implementation Method 2
thermosetting resin composition comprising a solid epoxy resin that is solid at 25° C., a non-solid epoxy resin that is non-solid at 25° C.
Data Source
AI summary
A thermosetting resin composition contains a solid epoxy resin that is solid at 25° C. a non-solid epoxy resin that is non-solid at 25° C., particulate rubber dispersed in the non-solid epoxy resin, a curing agent, an inorganic filler, and polycarbonate diol-derived polyurethane. The content of the particulate rubber is from 3 to 15 parts by mass with respect to the total parts by mass of the solid epoxy resin and the non-solid epoxy resin, the acid value of the polycarbonate diol-derived polyurethane is from 10 to 30 mgKOH/g, and the weight average molecular weight of the polycarbonate diol-derived polyurethane is from 15,000 to 50,000.