Dual Tg Polyimide Resin for Warpage-Free Metal-Clad Laminates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing process for preparing double-sided polyimide flexible circuit boards is complex, time-consuming, and prone to warpage due to the use of thermoplastic polyimide layers with low heat resistance and adhesion issues, which increases fabrication costs and reduces yield.
Innovation Solution
A novel polyimide resin with at least two glass transition temperatures is developed, allowing for improved adhesion upon hot pressing and reduced warpage, enabling the production of quasi double-sided two-layer metal clad laminates that can be easily separated into single-sided flexible circuit boards, simplifying the process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermoplastic polyimide layers are used in the existing process, then adhesion between layers can be achieved, but warpage occurs due to low heat resistance and poor dimensional stability
Solution Approach 1:
The patent changes the glass transition temperature parameter of the polyimide resin from a single low value (thermoplastic) to a dual-value system where one Tg is below and another is above the lamination temperature. This parameter change enables the resin to exhibit thermoplastic behavior during lamination (providing adhesion) while maintaining dimensional stability after lamination (preventing warpage), as the higher Tg ensures structural rigidity at processing temperatures.
2Ease of manufacture
If multiple coating and lamination steps are repeated in the existing process, then a double-sided polyimide FCCL can be prepared, but the process becomes complicated and time-consuming
Solution Approach 1:
The patent merges multiple separate coating and lamination steps into a single lamination operation. By designing a laminate structure where thermoplastic polyimide layers are positioned between two polyimide layers, the structure self-adheres during one lamination process, eliminating the need for repeated coating and lamination cycles while maintaining proper layer bonding.
Solution Approach 2:
The patent applies preliminary action by pre-positioning the thermoplastic polyimide layers between the polyimide layers before the final lamination step. This preliminary arrangement ensures that during the single lamination operation, the thermoplastic layers are already in place to provide adhesion, eliminating the need for subsequent bonding steps and simplifying the overall manufacturing process.
3Strength
If thermoplastic polyimide layers are used to provide adhesion, then layer bonding can be achieved, but foam and delamination occur during high temperature processing
Solution Approach 1:
The patent changes the thermal parameter profile by introducing a dual glass transition temperature system. The first Tg (below lamination temperature) allows thermoplastic flow and adhesion during bonding, while the second Tg (above lamination temperature) ensures the resin maintains structural integrity and resistance to foam/delamination during subsequent high-temperature processing, thereby improving yield.
4Ease of manufacture
If single-sided FCCL is used, then easy fabrication and low cost are achieved, but warpage occurs during circuit printing due to structural imbalance
Solution Approach 1:
The patent applies asymmetry by creating a symmetric laminate structure (polyimide-thermoplastic-polyimide) that balances forces on both sides. This symmetric construction eliminates the structural imbalance inherent in single-sided FCCL, preventing warpage during circuit printing while maintaining the fabrication ease and cost advantages of single-sided processing.
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 novel polyimide resin simplifies the production process, reduces warpage, and enhances the mechanical and thermal properties of the resulting flexible circuit boards, allowing for efficient fabrication of both single-sided and double-sided boards with improved adhesion and thermal stability.
Implementation Method 1
improved adhesion upon hot pressing
Implementation Method 2
adhesion upon hot pressing
Implementation Method 3
a first glass transition temperature in a range of about 270° C. to about 315° C. and a second glass transition temperature in a range of about 350° C. to about 450° C.
Data Source
AI summary
The present disclosure provides a polyimide resin having at least two glass transition temperatures measured by dynamic mechanical analysis (DMA). Also, a metal-clad laminate including the polyimide resin.