Foaming Adhesive Sheet for Motor Stator Coil Gap Filling
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Solution Overview
Problem
Conventional epoxy resin adhesives used in motor manufacturing face challenges such as difficulty in filling narrow gaps between stator and coil due to high viscosity, poor heat dissipation, and environmental concerns related to release paper waste, while existing adhesive sheets lack fast curability, heat resistance, and adequate thermal conductivity.
Innovation Solution
An adhesive sheet with an expandable adhesive layer containing a polyfunctional epoxy resin, phenol resin as a curing agent, an imidazole-based compound as a curing catalyst, and a temperature-sensitive foaming agent, which allows for rapid curing, excellent heat resistance, and good filling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid epoxy resin adhesive is injected into narrow clearance, then adhesion between stator and coil is achieved, but the adhesive cannot enter the clearance completely forming void spaces
Solution Approach 1:
The adhesive composition parameters are changed by adding a foaming agent that generates gas bubbles upon heating. This transforms the adhesive from a simple liquid to a foaming composition that expands and fills narrow clearances completely, eliminating void spaces while maintaining strong adhesion between stator and coil.
Solution Approach 2:
The adhesive undergoes phase transition from liquid to foam during the bonding process. When heated, the foaming agent generates gas bubbles that expand the adhesive into a foamed structure, enabling complete penetration into narrow clearances and ensuring void-free filling while maintaining reliable adhesion.
2Manufacturing precision
If clearance is enlarged to allow complete adhesive filling, then void spaces are eliminated, but heat dissipation performance decreases
Solution Approach 1:
Instead of changing the geometric parameter of clearance, the adhesive's physical parameters are changed by incorporating a foaming agent. The adhesive transforms into a foamed structure that expands in-situ to fill narrow clearances completely, achieving void-free bonding without requiring clearance enlargement, thus preserving heat dissipation efficiency.
3Strength
If liquid epoxy resin is heated for curing, then adhesion strength is achieved, but viscosity decreases causing adhesive to drip and pollute surrounding parts
Solution Approach 1:
The adhesive composition is modified by adding a foaming agent that triggers volume expansion upon heating. This parameter change causes the adhesive to foam and increase in volume during curing, which prevents dripping by creating a self-supporting foamed structure that maintains position while achieving strong adhesion without polluting surrounding parts.
4Ease of operation
If adhesive sheet with foamable epoxy resin is used, then workability is improved, but fast curability and heat resistance are insufficient
Solution Approach 1:
The adhesive sheet employs a composite material structure combining foamable epoxy resin with specific foaming agents and curing agents. This composite formulation achieves a balance between workability (through foaming expansion), fast curability (through efficient curing agent selection), and heat resistance (through stable cured structure), resolving the insufficiencies of previous adhesive sheets.
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 adhesive sheet achieves fast curability, balanced heat resistance and adhesiveness, and enhanced thermal conductivity, ensuring reliable adhesion and insulation between stator and coil, while eliminating the need for release paper.
Implementation Method 1
an expandable adhesive layer containing an epoxy resin and a temperature-sensitive foaming agent
Implementation Method 2
expanded, foamed and cured by heating
Implementation Method 3
a polyfunctional epoxy resin, a phenol resin as a curing agent
Implementation Method 4
an imidazole-based compound as a curing catalyst
Implementation Method 5
expanded, foamed and cured by heating
Data Source
AI summary
In an embodiment, an adhesive sheet has an expandable adhesive layer 2 on one side or both sides of a base 1, wherein the expandable adhesive layer 2 contains an epoxy resin including a polyfunctional epoxy resin, a phenol resin as a curing agent, an imidazole-based compound as a curing catalyst, and a temperature-sensitive foaming agent. The adhesive sheet has properties in good balance, such as fast curability, heat resistance, and adhesiveness, and also excellent properties such as thermal conductivity attributed to a good filling property.