Liquid Crystal Polymer Circuit Board Low-Temperature Bonding
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Solution Overview
Problem
Current circuit board manufacturing methods using thermoplastic liquid crystal polymer films require high-temperature processing, which is not compatible with existing equipment, leading to issues with heat resistance, dimensional stability, and solder heat resistance, especially in high-frequency applications.
Innovation Solution
A circuit board comprising a thermoplastic liquid crystal polymer film combined with an adhesive layer made of polyphenylene ether-based resin, which has a specific glass transition temperature, allowing for low-temperature thermo-compression bonding and maintaining excellent dielectric properties, heat resistance, and reduced transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If thermoplastic liquid crystal polymer films are used to achieve low dielectric constant and low dielectric loss, then transmission loss is reduced, but high-temperature processing is required which is not compatible with existing equipment
Solution Approach 1:
A silane-based adhesive layer is introduced as an intermediary between the thermoplastic liquid crystal polymer film and other circuit board components. This adhesive layer enables bonding at lower temperatures (below the polymer's melting point) through silane crosslinking, eliminating the need for high-temperature processing equipment while maintaining the low dielectric properties of the liquid crystal polymer film.
Solution Approach 2:
The invention changes the bonding mechanism parameter from thermal compression (requiring high temperature) to chemical bonding via silane crosslinking. This parameter change allows the thermoplastic liquid crystal polymer film to be processed at lower temperatures using existing equipment while preserving its excellent dielectric characteristics.
2Reliability
If thermoplastic liquid crystal polymer films are used to achieve heat resistance and dimensional stability, then performance is improved, but existing equipment cannot process at the required temperatures
Solution Approach 1:
The silane-based adhesive layer serves as a mediator that enables bonding without direct thermal contact between the liquid crystal polymer film and other components. The silane crosslinking mechanism provides strong adhesion at lower temperatures, allowing the use of existing equipment while maintaining the heat resistance and dimensional stability of the polymer film.
Solution Approach 2:
The invention replaces the thermal-mechanical bonding system (heat and pressure) with a chemical bonding system (silane crosslinking). This substitution eliminates the need for high-temperature processing equipment while maintaining the reliability and heat resistance properties of the thermoplastic liquid crystal polymer film.
3Strength
If high-temperature processing is used to bond thermoplastic liquid crystal polymer films, then adhesion is improved, but production cost increases due to specialized equipment requirements
Solution Approach 1:
The silane-based adhesive layer acts as an intermediary that provides strong interlayer adhesion through chemical crosslinking at lower temperatures. This eliminates the need for expensive high-temperature processing equipment while maintaining strong bonding, thereby reducing production costs.
Solution Approach 2:
The invention replaces expensive thermal-mechanical bonding equipment with a more economical chemical bonding approach using silane crosslinking. This substitution maintains strong adhesion strength while significantly reducing equipment investment and production costs.
4Ease of manufacture
If conventional adhesive layers are used with thermoplastic liquid crystal polymer films, then existing equipment can be used, but solder heat resistance is insufficient
Solution Approach 1:
The invention changes the adhesive layer composition to include silane-based resins with high glass transition temperatures and crosslinking capabilities. This parameter change enables the adhesive to maintain its bonding properties at soldering temperatures, providing both equipment compatibility and solder heat resistance.
Solution Approach 2:
The adhesive layer is formulated as a composite material containing silane-based resins, silane crosslinking agents, and potentially other functional additives. This composite structure provides both low-temperature processability for existing equipment and high-temperature resistance for soldering operations.
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 solution enables the production of circuit boards with improved heat resistance, solder heat resistance, and low transmission loss at high frequencies, while utilizing existing manufacturing equipment, thus reducing production costs and enhancing performance.
Implementation Method 1
a liquid crystal polymer film including a thermoplastic polymer capable of forming an optically anisotropic melt phase
Implementation Method 2
an adhesive layer comprising a polyphenylene ether-based resin, wherein the adhesive layer has a glass transition temperature of from 200° C. to 300° C.
Data Source
AI summary
A power supply path structure is provided for a flexible circuit board and includes a first flexible circuit board that includes at least one first connection pad and a first opposite connection pad and a first power supply path connected between the first connection pad and the first opposite connection pad and a second flexible circuit board that includes at least one second connection pad and a second opposite connection pad and a second power supply path connected between the second connection pad and the second opposite connection pad, and the first flexible circuit board is stacked, in a vertical direction, on the second flexible circuit board in such a way that the first power supply path and the second power supply path form a parallel-connected power supply path that serves as a power path or a grounding path for the first flexible circuit board.