Thin Film Magnetic Head Heating Element Electromigration Suppression
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Solution Overview
Problem
Existing thin film magnetic heads face issues with electromigration and temperature-dependent resistance changes in heating elements, leading to fluctuations in protrusion height and efficiency during long-term current application and temperature variations.
Innovation Solution
A thin film magnetic head design incorporating a heating element with a high-melting-point-material layer, such as platinum group elements or Ta, Ti, Cr, Nb, and Mo, disposed over or under a heating conductor layer like NiCu, CuMn, NiFe, W, or CrCu, to suppress electromigration and reduce temperature-dependent resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If current is applied to the heating element continuously for a long period of time, then the heating element can maintain thermal expansion function, but electromigration occurs causing marked resistance changes
Solution Approach 1:
The heating element is constructed as a composite structure with a heating conductor layer (such as Cu, NiCr, or CrCu) and a high-melting-point-material layer (such as Ru, Rh, Pd, Os, Ir, Pt, Ta, Ti, Cr, Nb, or Mo). This composite material structure suppresses electromigration by providing a protective layer that prevents material degradation during continuous operation, thereby maintaining resistance stability over extended periods.
2Adaptability or versatility
If the temperature dependency of the rate of change in resistance is large, then the heating element responds sensitively to temperature changes, but the resistance is markedly changed by environmental temperature variations
Solution Approach 1:
The composite structure of the heating element with specific material combinations (heating conductor layer + high-melting-point-material layer) inherently reduces the temperature coefficient of resistance. The high-melting-point-material layer acts as a stabilizing component that compensates for temperature-induced resistance changes in the heating conductor layer, achieving both temperature responsiveness and resistance stability.
3Adaptability or versatility
If the resistance of the heating element is markedly changed, then the heating element can adapt to different operating conditions, but the amount of heat generated markedly varies causing fluctuation in protrusion amount
Solution Approach 1:
The composite heating element structure with controlled material layers provides stable resistance characteristics that prevent marked resistance changes. This stability ensures consistent heat generation and maintains precise control over the thermal expansion-induced protrusion amount, eliminating fluctuations that would compromise manufacturing precision.
4Length of moving object
If the amount of protrusion becomes excessively large, then the thermal expansion effect is enhanced, but the thin film magnetic head is likely to collide with the recording medium
Solution Approach 1:
By using the composite heating element structure, the patent achieves stable and controlled thermal expansion. The consistent resistance prevents excessive heat generation that would cause over-expansion, thereby maintaining an optimal protrusion amount that enhances thermal expansion benefits while preventing collision with the recording medium.
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
This design effectively reduces resistance fluctuations due to electromigration and temperature changes, stabilizing heat generation and protrusion height, thereby enhancing write and read efficiency and preventing head collisions with the recording medium.
Implementation Method 1
a heating element that allows the surface of at least one of the read head and the write head that faces a recording medium to protrude toward the recording medium
Implementation Method 2
the magnetic gap and its vicinity are thermally expanded and the surface facing a recording medium is allowed to protrude toward the recording medium
Implementation Method 3
the heating element includes a heating conductor layer and a high-melting-point-material layer disposed so as to at least partially overlap the heating conductor layer. The high-melting-point-material layer has a melting point higher than that of the heating conductor layer. Because of the structure described above, the heating conductor layer does not easily cause electromigration compared with heating conductor layers formed by the existing techniques
Data Source
AI summary
A thin film magnetic head is provided. The thin film magnetic head includes a read head and a write head, a heating element, or the combination thereof. The heating element includes a heating conductor layer and a high-melting-point-material layer disposed so as to at least partially overlap the heating conductor layer. Electromigration in the heating conductor layer can be suppressed.