Photosensitive Compositions Using Latent Base Catalysts for Low-Temperature Curing

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Solution Overview

Problem

Conventional polyimides used in microelectronics and optoelectronics suffer from poor thermo-mechanical properties, high cure temperatures, and the use of toxic monomers, limiting their applications and processing efficiency.

Innovation Solution

Incorporating latent base generators, derived from cyclic anhydrides and amines, with aqueous base soluble polymers, such as polyamic acid, to form photosensitive compositions that exhibit improved thermo-mechanical properties and lower cure temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional polyimides are used to form positive tone compositions, then alkali solubility is achieved through toxic phenolic monomers, but the compositions suffer from poor thermo-mechanical properties and require high cure temperatures above 300°C

Engineering Contradiction:

Improvethermo-mechanical propertiesVSAvoidcure temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the chemical parameters of the polymer system by using polyamic acid instead of conventional polyimide, and incorporates latent base catalysts (imidazoles, triazoles, pyrimidines, or their salts) to modify the curing behavior. This parameter change enables the system to achieve proper crosslinking at lower temperatures (below 300°C) while maintaining or improving thermo-mechanical properties through the controlled release of base during curing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system by combining polyamic acid with latent base catalysts and photoactive compounds. This composite approach allows the polyamic acid to provide the base solubility needed for positive tone imaging, while the latent base catalysts enable low-temperature curing and improve thermo-mechanical properties through controlled crosslinking reactions

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If conventional polyimides are used, then positive tone imaging is achieved, but the compositions exhibit poor photo-imaging capabilities and insolubility in commonly used solvents

Engineering Contradiction:

Improvephoto-imaging capabilitiesVSAvoidsolubility in commonly used solvents

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the solubility parameter by using polyamic acid, which retains carboxylic acid groups that provide base solubility, unlike conventional polyimides that are insoluble. This parameter change enables the composition to be processed in commonly used solvents while maintaining positive tone imaging capabilities through the base solubility mechanism

Inventive Principle:

Principle #35Parameter changes

3Strength

If high cure temperatures above 300°C are used to achieve proper crosslinking, then crosslinking density is improved, but processing costs increase and thermal degradation risks increase

Engineering Contradiction:

Improvecrosslinking densityVSAvoidcure temperature

Core Design Contradiction:

StrengthVSUse of energy by stationary object

Solution Approach 1:

The patent changes the activation energy parameter of the crosslinking reaction by incorporating latent base catalysts. These catalysts remain stable at room temperature and low curing temperatures but become active at moderate temperatures (below 300°C), enabling the crosslinking reaction to proceed at lower temperatures while achieving adequate crosslinking density. This parameter change reduces the cure temperature from above 300°C to below 300°C, reducing energy consumption and thermal degradation risks

Inventive Principle:

Principle #35Parameter changes

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 compositions demonstrate enhanced thermo-mechanical properties, lower cure temperatures, and improved photo-imaging capabilities, enabling the formation of high-quality microelectronic and optoelectronic devices with improved tensile strength and glass transition temperatures.

Implementation Method 1

a latent base catalyst which upon heat releases the base

Methodology Applied

Scientific EffectThermal decomposition: Thermolysis

Implementation Method 2

a photoactive compound... exhibit improved photo-imaging capabilities

Methodology Applied

Scientific EffectPhotochemical reaction: Photopolymerisation

Data Source

PatentUS11061328B2Positive tone photosensitive compositions containing amic acid as latent base catalyst

Publication Date: 2021.07.13 SUMITOMO BAKELITE CO LTD

AI summary

Embodiments in accordance with the present invention encompass photosensitive compositions containing a base soluble polymer, a latent base catalyst, a photoactive compound and an epoxy crosslinking agent. The compositions are useful for forming films that can be patterned to create structures for microelectronic devices, microelectronic packaging, microelectromechanical systems, optoelectronic devices and displays. In some embodiments the compositions of this invention are shown to feature excellent hitherto unachievable mechanical properties. More specifically, the compositions exhibit increased photo speed, higher elongation to break, higher tensile strength and higher glass transitions temperatures than the conventional compositions, among other enhanced properties. Accordingly, the positive images formed therefrom exhibit improved thermo-mechanical properties, among other property enhancements.