Low-Hydroxyl Polyester Resin for High-Frequency Signal Integrity
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Solution Overview
Problem
Existing thermoplastic polyester resins fail to achieve sufficient dielectric loss tangent and mechanical properties in high frequency bands, particularly at 1 GHz or more, leading to signal degradation and reduced communication accuracy.
Innovation Solution
A thermoplastic polyester resin with reduced hydroxy group concentration and specific aliphatic groups at the molecular ends, combined with additional components to enhance mechanical properties and reduce dielectric loss tangent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low dielectric polyester resin is used to reduce dielectric loss tangent in high frequency band, then dielectric properties are improved, but mechanical properties and heat resistance deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester resin by controlling the ratio of terephthalic acid to other dicarboxylic acids, and by controlling the intrinsic viscosity (0.3-1.2 dl/g) and hydroxyl group concentration (≤0.050 mmol/g). These parameter changes enable simultaneous achievement of low dielectric loss tangent (≤0.0060 at 5.8 GHz) and good mechanical properties.
Solution Approach 2:
The patent creates a composite resin system by combining multiple components: terephthalic acid, other dicarboxylic acids (adipic acid, succinic acid, glutaric acid, or 1,3-propanediol), and diols (ethylene glycol, 1,3-propanediol, or 1,4-butanediol). This composite approach allows optimization of both dielectric properties and mechanical strength through synergistic effects of different monomers.
2Reliability
If the hydroxy group concentration is reduced to lower dielectric loss, then dielectric properties improve, but manufacturing complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges for hydroxyl group concentration (≤0.050 mmol/g) and intrinsic viscosity (0.3-1.2 dl/g) that can be achieved through controlled polymerization processes. By defining these parameters, the patent simplifies manufacturing by providing clear target values for process control rather than requiring complex real-time adjustments.
Solution Approach 2:
The patent incorporates hydroxyl group blocking agents during the polymerization process to prevent excessive hydroxyl group formation. This preliminary action during synthesis avoids the need for post-processing steps to reduce hydroxyl groups, thereby simplifying the overall manufacturing process while achieving the desired low dielectric loss properties.
Data Source
AI summary
The present invention provides a thermoplastic polyester resin comprising a residue of an aromatic dicarboxylic acid or an ester-forming derivative thereof and a residue of a diol or an ester-forming derivative thereof, as main structural units, wherein the thermoplastic polyester resin has a hydroxy group concentration of 0.050 mmol/g or less. The use of such a thermoplastic polyester resin enables to obtain a molded article which has excellent mechanical properties and heat resistance, and which also has a reduced dielectric loss tangent at a high frequency of 1 GHz or more.