Pressure-Sensitive Adhesive Tape With High Tg Shell Resin
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Solution Overview
Problem
Pressure-sensitive adhesive tapes with thermally expandable microspheres face a decrease in foaming temperature due to thermal history, leading to unintended reduction in adhesive strength during thermal shock tests, which is a challenge in high-temperature manufacturing environments for electronic parts.
Innovation Solution
A pressure-sensitive adhesive tape is developed with thermally expandable microspheres having a shell made of resin with a glass transition temperature of 120° C or more, containing a carboxyl group, and an organic solvent, which maintains adhesive strength and prevents foaming temperature decrease even after thermal cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermally expandable microspheres with foaming agent are used to achieve peelability at high temperature, then peelability is improved, but foaming temperature decreases due to thermal history causing unnecessary adhesive strength loss during thermal shock tests
Solution Approach 1:
The patent changes the glass transition temperature parameter of the shell resin from conventional values (below 120°C) to 120°C or higher. This parameter change prevents the shell from softening during thermal shock tests, maintaining stable adhesive strength while still allowing peelability through gravity action when heated to the foaming temperature. The elevated Tg ensures the shell maintains its structural integrity during thermal cycling without premature foaming.
Solution Approach 2:
The patent uses composite materials by combining specific resin types (acrylic resin, styrene resin, or polyolefin resin) with precise glass transition temperatures to form the shell structure. This composite approach allows the shell to exhibit both thermal stability during storage and thermal processing, and controlled expansion during peeling. The specific resin composition ensures resistance to thermal history effects while maintaining the desired peelability function.
2Ease of operation
If conventional foaming agents are used to enable easy peeling, then peelability is achieved, but adhesive strength is unnecessarily decreased during thermal shock tests due to foaming temperature reduction
Solution Approach 1:
The patent elevates the glass transition temperature parameter of the shell resin to 120°C or higher, which fundamentally changes the thermal behavior of the foaming agent system. This prevents the shell from undergoing premature softening and foaming during thermal shock tests, thereby maintaining adhesive strength while still enabling easy peeling through gravity action when heated to the designated foaming temperature.
3Ease of manufacture
If the shell resin has low glass transition temperature for easy processing, then manufacturing is easier, but foaming temperature stability decreases under thermal history
Solution Approach 1:
The patent changes the glass transition temperature parameter of the shell resin from conventional low values to 120°C or higher. This elevated Tg parameter ensures the shell maintains its dimensional stability and foaming temperature characteristics even after exposure to thermal history, while still allowing for practical manufacturing processes. The specific resin selection balances processability with thermal stability.
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 tape maintains a significant portion of its initial adhesive strength after thermal exposure, ensuring reliable temporary fixing and easy peelability, even after multiple heat cycles, thus addressing the issue of foaming temperature reduction and adhesive strength loss.
Implementation Method 1
when the pressure-sensitive adhesive tape is heated to a predetermined temperature (foaming temperature) or more, the foaming agent expands
Implementation Method 2
the volatile substance contained in the shell
Implementation Method 3
expresses a pressure-sensitive adhesive property during temporary fixing
Data Source
AI summary
A pressure-sensitive adhesive tape of the present invention includes thermally expandable microspheres, wherein the thermally expandable microspheres are each formed of a shell and a volatile substance contained in the shell, and wherein the shell is formed of a resin having a glass transition temperature (Tg) of 120° C. or more. In one embodiment, the resin for forming the shell contains a constituent unit having a carboxyl group.