Soft Magnetic Metal Strip Lamination via Controlled Imidization
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Solution Overview
Problem
Existing methods for producing soft magnetic metal strip laminates face challenges in achieving sufficient soft magnetic properties, high adhesion strength, and high space factor without embrittlement from heat treatment, and often result in internal delamination due to voids within the laminate.
Innovation Solution
A process involving the application of a polyamide acid solution on soft magnetic metal strips, followed by a semidrying heat treatment to achieve a degree of imidization between 15% to 70%, and a subsequent high-temperature heat treatment to achieve over 90% imidization, ensuring strong adhesion and high space factor through controlled polyimidization reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous metal strip is subjected to annealing heat treatment at 300 to 600°C to obtain soft magnetic characteristics, then soft magnetic property is improved, but the metal strip is embrittled
Solution Approach 1:
The patent applies polyimide resin or polyamideimide resin to the amorphous metal strip before heat treatment. This preliminary coating action protects the metal strip during subsequent annealing, preventing embrittlement while allowing the necessary soft magnetic properties to develop
Solution Approach 2:
The patent creates a composite structure by combining amorphous metal strip with polyimide or polyamideimide resin. This composite material allows the metal to achieve soft magnetic characteristics through heat treatment while the resin matrix prevents embrittlement, maintaining structural strength
2Temperature
If polyimide resin or polyamideimide resin is applied on amorphous metal strip and heat treated at 200°C or more to ensure heat resistance, then heat resistance is improved, but the degree of imidization becomes too high before lamination causing inflated surface
Solution Approach 1:
The patent applies a preliminary drying treatment at 80 to 150°C before lamination to remove solvent from the polyamide acid solution without causing excessive imidization. This preliminary action controls the degree of imidization to 15-70%, preventing surface inflation during subsequent high-temperature heat treatment
Solution Approach 2:
The patent controls the degree of imidization as a key parameter, maintaining it between 15-70% before lamination and achieving over 90% after final heat treatment. This parameter control prevents premature cross-linking that would cause surface inflation while ensuring adequate adhesion
3Strength
If polyamide acid solution is applied on amorphous metal strip and dried at 130°C with high degree of imidization, then adhesion strength is improved, but the space factor decreases due to excessive resin reaction before lamination
Solution Approach 1:
The patent performs preliminary drying at 80 to 150°C to remove solvent and initiate partial imidization (15-70%) without completing the reaction. This preliminary action provides adequate adhesion while leaving room for further imidization after lamination, maintaining high space factor
Solution Approach 2:
The patent applies partial imidization (15-70%) before lamination rather than complete imidization. This partial action provides sufficient adhesion strength while avoiding excessive resin cross-linking that would reduce space factor. The remaining imidization (to over 90%) occurs after lamination when volume constraints are established
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 process results in a soft magnetic metal strip laminate with a space factor of 95% or more and high adhesion reliability, minimizing internal delamination and maintaining excellent magnetic properties.
Implementation Method 1
a degree of imidization of the polyamide acid solution, which is in the range of 15 to 70%... a degree of imidization of the polyamide acid solution, which is over 90%
Implementation Method 2
drying the soft magnetic metal strip to obtain a degree of imidization of the polyamide acid solution, which is in the range of 15 to 70%
Data Source
Figure 1
AI summary
A soft magnetic metal strip laminate that has high adhesion strength between metal strips, free from delamination, an excellent magnetic property, a high space factor, and a process for production thereof. A process for production of a soft magnetic metal strip laminate that includes plural soft magnetic metal strips laminated by using a polyamide acid solution includes the steps of applying the polyamide acid solution on the soft magnetic metal strip, performing semicuring heat treatment to obtain the degree of imidization of the polyamide acid solution which is in the range of 15 to 70%, laminating plural soft magnetic metal strips to each other through the polyamide acid solution, and performing the heat treatment of the heating and the hot pressing to obtain the degree of imidization of the polyamide acid solution which is more than 90%.