Liquid Crystal Polyester Composition Cracking Resistance
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Solution Overview
Problem
Conventional liquid crystal polyester compositions exhibit anisotropy during molding, leading to warping and cracking issues, especially in compacts with thin sections or complex shapes, such as CPU sockets, during reflow mounting and pin insertion.
Innovation Solution
A liquid crystal polyester composition comprising a liquid crystal polyester, a plate-like filler with a volume-average particle size of 14 μm or greater, and a fibrous filler, with a total content of 45-55 wt% and a weight ratio of fibrous filler to plate-like filler between 0.5 and 0.65, which reduces anisotropy and enhances cracking resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If liquid crystal polyester is molded into compacts with thin sections or complex shapes, then the mechanical strength and heat resistance are improved, but anisotropy of shrinkage and expansion coefficients causes warping and cracking
Solution Approach 1:
The patent uses a composite material system consisting of liquid crystal polyester combined with both plate-like filler (40-50 wt%) and fibrous filler (5-20 wt%). This composite structure reduces anisotropy by distributing stress more uniformly throughout the material, preventing warping and cracking while maintaining mechanical strength and heat resistance in thin-section and complex-shaped compacts.
2Stability of the object's composition
If plate-like filler and fibrous filler are added to liquid crystal polyester to reduce anisotropy, then the uniformity of shrinkage and expansion is improved, but the total content of fillers must be precisely controlled to avoid excessive stiffness
Solution Approach 1:
The patent specifies precise parameter ranges: plate-like filler at 40-50 wt%, fibrous filler at 5-20 wt%, with their weight ratio controlled at 0.2-0.5. These parameter changes optimize the balance between reducing anisotropy and maintaining processability, ensuring uniform shrinkage and expansion without excessive stiffness that would complicate manufacturing.
3Ease of manufacture
If conventional filler ratios are used (fibrous filler/plate-like filler ratio >0.5 or <0.17), then the processing is simplified, but cracking occurs during reflow mounting and pin insertion
Solution Approach 1:
The patent identifies and applies a critical parameter range for the weight ratio of fibrous filler to plate-like filler (0.2-0.5), which differs from conventional ranges. This parameter change achieves optimal cracking resistance during reflow mounting and pin insertion while maintaining ease of manufacturing, resolving the contradiction between processing simplicity and reliability.
Data Source
AI summary
To provide a liquid crystal polyester composition that yields compacts that are resistant to cracking. A plate-like filler with a volume-average particle size of 14 μm or greater and a fibrous filler are combined with a liquid crystal polyester to form a liquid crystal polyester composition. The total content of the plate-like filler and the fibrous filler is 45-55 wt % with respect to the total of the liquid crystal polyester composition. The weight ratio of the fibrous filler content to the plate-like filler content is greater than 0.5 and not greater than 0.65.