Three-Layer LCP Extruded Film for MD/TD Dimensional Stability
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Solution Overview
Problem
Conventional thermoplastic liquid crystal polymer films exhibit high molecular orientation and anisotropy, leading to significant differences in dimensional change rates between the machine direction (MD) and transverse direction (TD), which hinder their use as insulating materials for circuit substrates, particularly in ultrafine processing applications.
Innovation Solution
A two-kind three layer co-extrusion method is employed to produce an LCP extruded film with controlled molecular orientation and internal strain, using a thermoplastic resin and thermoplastic liquid crystal polymer layers, with specific conditions to reduce anisotropy and dimensional change rates, and a subsequent removal of outer layers to achieve a homogeneous intermediate layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If single layer extrusion is used to produce thermoplastic liquid crystal polymer film, then the manufacturing process is simple, but the film exhibits high molecular orientation and anisotropy leading to poor thickness accuracy and surface flatness
Solution Approach 1:
The patent divides the extrusion process into multiple layers (three-layer co-extrusion structure) where the LCP layer is sandwiched between thermoplastic resin layers. This segmentation allows the outer layers to protect the LCP layer from excessive orientation while the LCP layer maintains its intrinsic properties, resolving the contradiction between simple processing and high precision film quality.
Solution Approach 2:
The patent creates a composite structure combining thermoplastic liquid crystal polymer with thermoplastic resins (such as polyolefin or polycarbonate). This composite approach allows the LCP to provide high-frequency characteristics and low dielectric properties while the thermoplastic resin matrix reduces molecular orientation and anisotropy, achieving both manufacturability and precision.
2Reliability
If thermoplastic liquid crystal polymer is used for insulating material in circuit substrate, then high frequency characteristics and low dielectric properties are achieved, but significant dimensional change rate difference between MD and TD directions occurs
Solution Approach 1:
The patent changes the structural parameters of the film by creating a multi-layer composite structure and controlling the orientation parameters during extrusion. This reduces the anisotropy of dimensional change rates while preserving the LCP's excellent dielectric properties and high-frequency characteristics needed for circuit substrates.
3Productivity
If conventional extrusion method is used for LCP film, then production efficiency is maintained, but high molecular orientation causes peeling of skin layer and fibrillated fiber
Solution Approach 1:
The patent applies beforehand cushioning by introducing thermoplastic resin layers that wrap and protect the LCP layer during extrusion. These outer layers act as a cushion that prevents excessive shear stress and molecular orientation at the skin layer interface, preventing peeling and fibrillation while maintaining production efficiency.
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 method results in an LCP extruded film with reduced molecular orientation and internal strain, enabling high dimensional stability and suitability for ultrafine processing, suitable for insulating materials and metal foil-clad laminates.
Implementation Method 1
Liquid crystal polymers (LCP) are polymers that exhibit liquid crystallinity in a molten state or a solution state. Especially, thermotropic liquid crystal polymers that exhibit liquid crystallinity in a molten state can be extruded and have excellent properties such as high gas barrier properties, high film strength, high heat resistance, high insulation properties, low water absorption, and low dielectric characteristics in a high frequency area.
Implementation Method 2
A two-kind three layer co-extrusion method is employed to produce an LCP extruded film with controlled molecular orientation and internal strain, using a thermoplastic resin and thermoplastic liquid crystal polymer layers, with specific conditions to reduce anisotropy and dimensional change rates
Data Source
AI summary
The present invention provides an LCP extruded film comprising a thermoplastic liquid crystal polymer and having a thickness of 15 μm or more and 300 μm or less, wherein coefficients of linear thermal expansion in a MD direction and a TD direction at 23 to 200° C. as measured by a TMA method according to JIS K7197 are each within a range of −30 to 55 ppm/K, and the following conditions (A) and/or (B) are satisfied, and a method for manufacturing the same, an LCP extruded film for stretch treatment, an LCP stretched film, a heat-shrinkable LCP stretched film, an insulating material for a circuit substrate, and a metal foil-clad laminate:(A) a degree of orientation α1(%) of a film surface S1 exposed and a degree of orientation α2(%) of a film surface S2 located at a depth of 5 μm from the film surface S1 satisfy a relationship of −4.0≤[(α2−α1)/α1]×100≤0.0;(B) a hardness H1 at a point of a depth of 1 μm located at a position of 1 μm from a film surface in a thickness direction and a hardness H2 at a thickness center point, as measured by subjecting a film cross section in parallel with a MD direction to a nanoindentation method, satisfy −10.0≤100×(H2−H1)/H1≤0.0.