Liquid Crystal Polyester Composition for Low-Loss, Low-Expansion Laminates
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Solution Overview
Problem
Existing liquid crystal polyester resins face issues with high dielectric loss tangent at high temperature, low elastic modulus, and high linear expansion coefficient, which are exacerbated in high-frequency applications and heat-treated laminates.
Innovation Solution
A liquid crystal polyester resin composition with specific structural units, including 42 to 80 mol% of 6-hydroxy-2-naphthoic acid-derived units, controlled entropy of melting (ΔS) between 0.01 × 10 -3< to 2.7 × 10 -3< J/g·K, and additional units to achieve low dielectric loss tangent, high elastic modulus, and low linear expansion coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the liquid crystal polyester resin includes a certain amount of 6-hydroxy-2-naphthoic acid structural unit to improve barrier properties, then barrier properties are enhanced, but dielectric loss tangent becomes high at high temperature
Solution Approach 1:
The patent applies parameter changes by precisely controlling the content of 6-hydroxy-2-naphthoic acid structural units within 42-80 mol% and controlling the entropy of melting (ΔS) within 0.01×10^-3 to 2.7×10^-3 J/g·K. This optimized parameter range achieves both low dielectric loss tangent at high temperature and enhanced barrier properties, resolving the contradiction between these two properties.
2Ease of operation
If the liquid crystal polyester resin has low elastic modulus and high linear expansion coefficient, then processing flexibility is improved, but dimensional stability deteriorates
Solution Approach 1:
The patent resolves this contradiction by changing the parameters of the resin composition, specifically controlling the content of 6-hydroxy-2-naphthoic acid units (42-80 mol%) and entropy of melting (ΔS: 0.01×10^-3 to 2.7×10^-3 J/g·K). These parameter optimizations simultaneously achieve high elastic modulus (≥1.0 GPa) and low linear expansion coefficient (≤15 ppm/°C), providing both processing flexibility and dimensional stability.
3Adaptability or versatility
If the liquid crystal polyester resin is used in high-frequency applications, then communication performance is improved, but transmission loss increases
Solution Approach 1:
The patent addresses this contradiction by optimizing the resin parameters (6-hydroxy-2-naphthoic acid content: 42-80 mol%, ΔS: 0.01×10^-3 to 2.7×10^-3 J/g·K) to achieve low dielectric loss tangent at high temperature. This enables the resin to maintain low transmission loss even in high-frequency applications, thereby improving adaptability to high-frequency environments.
4Strength
If the laminate undergoes heat treatment to improve mechanical properties, then strength is enhanced, but deformation occurs due to differential thermal expansion
Solution Approach 1:
The patent resolves this contradiction by changing the thermal expansion parameters of the resin through controlled composition (6-hydroxy-2-naphthoic acid units: 42-80 mol%, ΔS: 0.01×10^-3 to 2.7×10^-3 J/g·K). This achieves low linear expansion coefficient (≤15 ppm/°C), minimizing differential thermal expansion with metal foils during heat treatment and preventing laminate deformation while maintaining enhanced mechanical strength.
Data Source
AI summary
Disclosed is a liquid crystal polyester resin which includes 42 to 80 mol% of the following structural unit (I) relative to 100 mol% of the total structural unit of the liquid crystal polyester resin, and ΔS (entropy of melting) defined by the following equation [1] is 0.01 × 10-3 to 2.7 × 10-3 J/g·K: ΔSJ/g⋅K=ΔHmJ/g/TmK wherein Tm means an endothermic peak temperature determined as follows: after observation of an endothermic peak temperature (Tm1) observed when heating a liquid crystal polyester under temperature rising conditions of 20°C/minute from room temperature in differential scanning calorimetry, the liquid crystal polyester was maintained at the temperature of Tm1 + 20°C for 5 minutes, followed by observation of the endothermic peak temperature observed when the temperature is once fallen to room temperature under temperature falling conditions of 20°C/minute and then raised again under temperature rising conditions of 20°C/minute, and ΔHm is an endothermic peak area of Tm.