Multi-Layer Flexible Circuit Board High Temperature Lamination
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Solution Overview
Problem
Conventional flexible circuit boards are limited to single or double layers due to inferior heat endurance and high dielectric constant adhesives, which hinder the production of multi-layered circuits with high resolution and integration, and the manufacturing methods are complex and costly.
Innovation Solution
A circuit board process utilizing high temperature lamination with specific polyimide and adhesive layers, allowing for the creation of multi-layered boards with a glass transition temperature between 140° C and 160° C, enabling compatibility with printed circuit board processing equipment and reducing thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional adhesive is used in flexible circuit boards, then the board can be manufactured with simple process, but the adhesive has high dielectric constant which is unfavorable to circuits with high resolution and integration
Solution Approach 1:
The patent changes the dielectric constant parameter of the adhesive material by selecting specific polymer materials with low dielectric constants (e.g., polyimide with εr<3.0), thereby improving circuit signal quality and resolution without fundamentally altering the manufacturing process complexity
Solution Approach 2:
The patent uses composite material structures combining polyimide adhesive layers with copper conductive layers and polyethylene terephthalate films, creating a multi-layer composite that achieves both low dielectric constant and mechanical flexibility while maintaining manufacturability
2Manufacturing precision
If high temperature lamination process is adopted, then multi-layered circuit structure can be formed, but the existing flexible circuit layers have inferior heat endurance and cannot withstand high temperature
Solution Approach 1:
The patent raises the glass transition temperature parameter of the adhesive material from conventional low-Tg adhesives to polyimide with Tg≥140°C, enabling the material to withstand high temperature lamination processes (160-200°C) required for forming multi-layered circuit structures with high reliability
Solution Approach 2:
The patent performs preliminary heat treatment and curing of the polyimide adhesive layers before final assembly, pre-establishing the thermal stability and adhesive properties needed to withstand subsequent high temperature lamination processes without degradation
3Productivity
If conventional fast press step is used for bonding, then the process is simple and quick, but high temperature and long time press are not available limiting the circuit board to single or double layered structure
Solution Approach 1:
The patent changes the temperature and time parameters of the lamination process from conventional fast press (low temperature, short time) to high temperature lamination (160-200°C, extended duration), enabling effective bonding of multiple layers while maintaining manufacturing efficiency through optimized process parameters
Solution Approach 2:
The patent implements continuous high temperature lamination processing that maintains consistent thermal conditions throughout the bonding process, enabling uniform adhesion across all layers of multi-layered circuit boards without interrupting the manufacturing flow
4Length of stationary object
If glass fabric with short fiber is used to reduce thickness of printed circuit board, then the thickness is reduced, but the glass fabric with short fiber costs high
Solution Approach 1:
The patent uses thin polyimide adhesive films and polyethylene terephthalate films as structural components that provide both thickness reduction and mechanical strength, replacing expensive short fiber glass fabric while achieving the same thinning objective at lower cost
Solution Approach 2:
The patent employs cost-effective polyimide and polyethylene terephthalate materials that can be processed through standard manufacturing techniques, providing an economical alternative to expensive short fiber glass fabric for thickness reduction 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
This process enables the rapid and reliable manufacturing of multi-layered circuit boards with improved heat endurance and flexibility, compatible with existing printed circuit board equipment, while reducing production costs and thickness.
Implementation Method 1
the fourth adhesive layer is bonded to the first conductive layer
Implementation Method 2
a first lamination step is performed with a temperature higher than 160° C. to laminate the first lamination unit and the core unit
Data Source
AI summary
A circuit board, structural units and a manufacturing method are provided, wherein one or more high temperature lamination processes are conducted for laminating the structural units and form a multi-layered circuit board.