Polyester Resin Film for Electronic Substrates with Low Moisture Absorption
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Solution Overview
Problem
Conventional substrate films for electronic boards suffer from moisture absorption, poor thermal resistance, unsuitable electrical properties, and high costs, leading to insulation deterioration and dimensional instability under high temperature and humidity conditions.
Innovation Solution
A film and laminate for electronic boards are developed using a polyester resin polymerized with 1,4-cyclohexanedimethanol and aromatic dicarboxylic acid, which exhibits a moisture absorption rate of less than 0.3% relative to the initial weight when immersed in water at room temperature for 24 hours, enhancing moisture resistance and dimensional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional substrate films (polyimide, PEN, LCP) are used, then the electronic board can be manufactured, but the film absorbs moisture under high temperature and humidity conditions, resulting in insulation deterioration and dimensional instability
Solution Approach 1:
The patent changes the chemical composition parameters of the substrate film by using a specific polyester resin with controlled moisture absorption rate (less than 0.3%), glass transition temperature (80-110°C), and crystallinity (30-50%). This resolves the contradiction by selecting material parameters that inherently resist moisture absorption while maintaining insulation performance under high temperature and humidity conditions.
Solution Approach 2:
The patent employs a composite structure consisting of a polyester resin substrate layer and a conductive pattern layer. The polyester resin serves as a moisture-resistant base material that protects the conductive pattern from moisture ingress, thereby maintaining insulation performance. The composite structure combines the moisture resistance of polyester with the electrical functionality of the conductive pattern.
2Temperature
If conventional substrate films are used, then the electronic board can be manufactured, but the film lacks thermal resistance and has poor dimensional stability with respect to changes in temperature and humidity
Solution Approach 1:
The patent specifies precise parameter ranges for the polyester resin: glass transition temperature of 80-110°C and crystallinity of 30-50%. These parameter changes ensure the material maintains dimensional stability across temperature variations while providing adequate thermal resistance. The controlled crystallinity prevents excessive shrinkage or deformation during manufacturing and use.
3Reliability
If conventional substrate films are used, then the electronic board can be manufactured, but the electrical properties such as dielectric constant with respect to temperature are not suitable
Solution Approach 1:
The patent selects a polyester resin with a glass transition temperature of 80-110°C, which optimizes the dielectric constant stability across the operating temperature range. By controlling the glass transition temperature parameter, the material maintains suitable electrical properties without excessive temperature dependence, resolving the contradiction between electrical performance and thermal stability.
4Reliability
If conventional substrate films are used, then the electronic board can be manufactured, but it is rather expensive
Solution Approach 1:
The patent employs a polyester resin-based substrate film that offers comparable performance to expensive conventional materials (polyimide, PEN, LCP) at a lower cost. The polyester resin provides adequate moisture resistance, thermal stability, and electrical properties for electronic board applications, achieving cost-effective manufacturing without sacrificing essential performance requirements.
Data Source
AI summary
A film for an electronic substrate according to an embodiment has a moisture-absorption rate of less than 0.3% of the initial weight when immersed in water for 24 hours, and thus is less susceptible than existing films for electronic substrates are to changes in dimension or degradation in electrical characteristics caused by containing moisture according to changes in temperature and humidity. Also, the film for an electronic substrate is equal or superior to existing films in terms of flexibility and physicochemical characteristics, and thus may be applied to the manufacture of laminates with a conductive film such as FCCL and electronic substrates such as FPCB to improve processability, durability, transmission capacity, etc.