Block Polyimide Low Thermal Expansion Circuit Substrates
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Solution Overview
Problem
Existing polyimide layers face challenges with warpage due to thermal expansion mismatch between substrates and polyimide resin layers, and have issues with solubility in alkaline solutions affecting patterning precision.
Innovation Solution
A block polyimide and block polyamic acid imide with specific structural units and ratios, providing moderate solubility in alkaline solutions and low coefficient of linear thermal expansion, are developed, allowing for precise patterning and reduced warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polyimide containing cyclohexanediamine (CHDA) is used to achieve high transparency and low CTE, then transparency and thermal expansion properties are improved, but material cost increases
Solution Approach 1:
The patent uses a block copolymer structure combining CHDA-containing polyamic acid blocks (providing transparency and low CTE) with other diamine-containing polyimide blocks (reducing cost). This composite approach allows the material to exhibit both high transparency and low thermal expansion while reducing reliance on expensive CHDA throughout the entire polymer structure.
Solution Approach 2:
The invention applies local quality by concentrating the expensive CHDA component specifically in certain blocks of the copolymer rather than uniformly throughout. The CHDA blocks are localized to provide the necessary optical and thermal properties in critical regions, while other blocks use more economical diamines.
2Illumination intensity
If a block polyamic acid imide structure is used to achieve low CTE and high transparency, then optical and thermal properties are improved, but solubility in alkaline solution decreases
Solution Approach 1:
The patent creates a composite block copolymer where CHDA-containing polyamic acid blocks (providing transparency and low CTE) are combined with other diamine-containing polyimide blocks. This composite structure maintains the desirable optical and thermal properties while the overall copolymer architecture preserves sufficient solubility in alkaline solutions for patterning applications.
Solution Approach 2:
The invention changes the structural parameters of the polyimide by creating a block copolymer with specific block lengths and compositions. By controlling the average number of repeating units (m and n) in each block type and their ratio, the patent optimizes both the solubility parameter and the optical/thermal properties simultaneously.
3Ease of manufacture
If polyamic acid with excessive solubility is used to achieve easy processing, then processability is improved, but patterning precision deteriorates
Solution Approach 1:
The patent optimizes the solubility parameter by controlling the block structure and composition of the copolymer. The average number of repeating units (m and n) and their ratio are carefully selected to achieve moderate solubility in alkaline solutions, which provides sufficient processability while preventing excessive dissolution that would compromise patterning precision.
Data Source
AI summary
Provided are a block polyamide acid imide having an appropriate solubility in aqueous alkaline solutions, and block polyimides that are obtained using same and have high transparency and a low coefficient of linear thermal expansion (low CTE). The block polyimide comprises blocks configured from repeating structural units represented by defined formula (1A) and blocks configured from repeating structural units represented by defined formula (1B).