Curable Polyimide Composition for Low-Temperature Film Curing
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Solution Overview
Problem
Existing polyimide materials used in electronics face challenges such as instability at high temperatures, moisture absorption, delamination, and difficulty in processing, which affect their performance in applications like semiconductor packaging, wafer processing, and shape memory polymer requirements.
Innovation Solution
Development of high molecular weight, flexible polyimide resins with curable moieties that are heat-, UV-, and self-curable, featuring a structure with pendant alcohol groups functionalized to form a polyimide with molecular weights greater than 20,000 Daltons, suitable for use in adhesive compositions, coatings, and redistribution layers, and capable of forming stable films without the need for high-temperature 'hard bake' steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyimide films are used, then good chemical resistance and dimensional stability are achieved, but they cannot be cured and remain tacky at room temperature
Solution Approach 1:
The patent introduces latent curing agents that remain dormant at room temperature but activate at elevated temperatures (e.g., 80-150°C). This parameter change in the curing agent's activation temperature allows the film to be non-tacky during handling at room temperature while enabling cure upon heating, resolving the contradiction between room temperature tackiness and chemical resistance.
Solution Approach 2:
The polyimide film is pre-formed with good dimensional stability and chemical resistance properties before curing. The latent curing agent is incorporated in advance, ready to activate when exposed to heat, allowing the film to maintain its stable properties during processing while enabling subsequent curing to eliminate tackiness.
2Stability of the object's composition
If conventional polyimide films are used, then good dimensional stability is achieved, but they cannot be cured and remain tacky
Solution Approach 1:
The patent uses latent curing agents with specific activation temperature ranges (80-150°C) that are below the polyimide's glass transition temperature. This parameter selection ensures the curing reaction occurs without compromising dimensional stability, while still eliminating room temperature tackiness after curing.
Solution Approach 2:
The latent curing agent acts as an intermediary that bridges the contradiction between dimensional stability and tackiness. It remains inactive during handling to preserve dimensional stability, then activates under controlled heating to eliminate tackiness without affecting the already-established dimensional stability of the polyimide matrix.
3Reliability
If excess diamine is used to ensure complete reaction, then conversion is improved, but viscosity increases and handling becomes difficult
Solution Approach 1:
The patent employs pre-formed polyimide polymers with terminal carboxylic acid groups, eliminating the need for in-situ polymerization. This preliminary preparation allows the use of stoichiometric or slight excess of diamine without causing high viscosity issues, as the polymerization has already occurred and the system is simply undergoing a curing reaction with the latent agent.
Solution Approach 2:
The patent changes the reaction parameters by using pre-polymerized polyimide rather than monomers. This parameter change allows for better control of stoichiometry and reduces viscosity concerns, as the pre-polymerized material has already achieved the desired molecular weight and structure before the curing step with the latent agent.
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 resulting polyimide compositions exhibit high temperature stability, reduced moisture absorption, and improved processing ease, enabling their use in high-temperature applications, such as backgrinding and dicing, while maintaining mechanical strength and flexibility, thus addressing the limitations of traditional polyimides.
Implementation Method 1
curable polyimide compositions and articles comprising crosslinkable polyimide polymers and latent curing agents
Implementation Method 2
The curable polyimide compositions and articles disclosed herein provide good dimensional stability and chemical resistance, and can be cured at relatively low temperatures
Data Source
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Figure 10A~10B
Figure 11A~11B
AI summary
The present invention provides curable, high molecular weight (>20,000 Daltons) polyimide compounds. The polyimides, once cured, possess a wide range of glass transition temperatures, have high tensile strength and high elongation. Furthermore, the cured polyimides are hydrophobic, have high glass transition temperatures, low coefficient of thermal expansion, very low dielectric constant and very low dielectric dissipation factor.