Low-Dk PBT Composition for Automotive Radar Components
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current materials with high dielectric constants and dissipation factors are not suitable for high-frequency applications like 5G radar due to signal distortion, heat generation, and breakdown under intense electric fields, and they also pose challenges in laser welding of partially crystalline thermoplastics like PBT, which affects the efficiency of automotive radar components.
Innovation Solution
A polybutylene terephthalate (PBT) composition with a specific range of dielectric constant (Dk) and dissipation factor (Df) is developed, incorporating glass fibers with low Dk and Df values, along with secondary polymers and impact modifiers, to enhance laser welding performance and maintain low dielectric properties, suitable for high-frequency applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional fillers (glass fiber, carbon fiber, minerals) are incorporated to enhance mechanical performance, then mechanical strength and modulus are improved, but dielectric constant and dissipation factor increase, deteriorating high-frequency radar performance
Solution Approach 1:
The patent changes the dielectric parameters of the filler material by selecting glass fibers with specifically controlled Dk (3.5-4.5) and Df (<0.003) values. This parameter optimization allows the filler to provide mechanical reinforcement while maintaining compatible dielectric properties with the PBT matrix, preventing the deterioration of high-frequency radar performance.
Solution Approach 2:
The patent creates a composite material system consisting of PBT matrix combined with low-Dk glass fibers. This composite structure achieves both mechanical enhancement and dielectric compatibility, as the glass fiber composite maintains similar dielectric properties to pure PBT while providing the necessary structural strength.
2Strength
If reinforcing fillers are added to improve mechanical performance, then strength and modulus increase, but laser transmission is reduced due to light scattering at interfaces
Solution Approach 1:
The patent optimizes the refractive index parameter of the glass fiber filler to match the PBT matrix (n=1.5-1.6), reducing the refractive index difference at the interface. This parameter control minimizes light scattering and improves laser transmission while maintaining mechanical reinforcement.
Solution Approach 2:
The patent applies surface treatment to the glass fiber filler to modify the local interface properties. By controlling the surface characteristics and refractive index matching at the fiber-matrix interface, the patent reduces scattering effects while preserving the reinforcing function.
3Reliability
If glass fiber is added to reduce dielectric constant, then Dk and Df decrease, but laser welding performance deteriorates due to increased light scattering
Solution Approach 1:
The patent precisely controls the glass fiber parameters (Dk: 3.5-4.5, Df: <0.003, refractive index: 1.5-1.6) to achieve dielectric performance compatible with high-frequency radar while minimizing interference with laser welding. The optimized parameter range reduces light scattering enough to maintain acceptable laser transmission for welding applications.
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 PBT composition achieves improved laser welding performance and maintains low dielectric constants and dissipation factors, ensuring high-frequency signal integrity and reliability in radar components, while also addressing the challenges of signal distortion and heat generation.
Implementation Method 1
Materials with high dielectric constant (Dk) or dissipation factor (Df) will reflect and absorb more EM waves respectively
Implementation Method 2
Electromagnetic (EM) waves propagated into plastic materials results in reflection, absorption and transmittance behaviors
Implementation Method 3
The energy loss will generate heat and influence the use
Implementation Method 4
High performance materials are often obtained by incorporating glass fiber, carbon fiber or minerals
Implementation Method 5
Partially crystalline thermoplastics have a spherulitic microstructure containing phases with a different refractive power
Implementation Method 6
the laser beam is widened more, and the backward scattering is greater
Data Source
AI summary
The invention discloses a polybutylene terephthalate composition comprising as component (A) polybutylene terephthalate resin in an amount of from 40wt% to 90wt%, as component (B) glass fiber having low dielectric constant and dissipation factor measured according to GB 9534-88 in an amount of 10wt% to 60wt%. The invention also disclosed a radar device component containing the polybutylene terephthalate composition.