Thin Film Magnetic Head Coil Insulation
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Solution Overview
Problem
In solenoid type thin film magnetic heads, heat expansion of insulating resist layers can cause the recording element portion to protrude towards the recording medium, potentially damaging it, and CMP processing can lead to resist smear due to the difficulty in completely burying spaces between coil contact layers with alumina.
Innovation Solution
The use of an insulating resist layer only between coil contacts and an inorganic insulating layer, such as Al2O3 or SiO2, to bury spaces between coil contact groups, controlling heat expansion and preventing protrusion while minimizing resist smear during CMP processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating resist layer is used to bury spaces between coil contact layers, then insulation between coil contacts is achieved, but heat expansion causes recording element portion to protrude toward recording medium
Solution Approach 1:
The patent changes the material parameter by replacing insulating resist with inorganic insulating material (alumina) that has superior thermal stability and minimal heat expansion. This material substitution resolves the contradiction by maintaining insulation reliability while preventing heat-induced protrusion of the recording element portion.
Solution Approach 2:
The patent employs a composite structure combining inorganic insulating material (alumina) with coil contact layers. This composite approach achieves both insulation between coil contacts and resistance to thermal expansion, as the inorganic material provides structural stability while maintaining electrical insulation properties.
2Manufacturing precision
If alumina is used to bury spaces between coil contact layers, then heat expansion is reduced, but it is difficult to completely bury the spaces due to narrow pitch gap, causing pores to occur
Solution Approach 1:
The patent segments the insulation function into two distinct components: inorganic insulating material (alumina) for thermal stability and pore prevention, combined with insulating resist for complete space filling. This segmentation allows each material to optimize its specific function, resolving the contradiction between protrusion control and insulation completeness.
Solution Approach 2:
The patent uses a composite filling approach where inorganic insulating material provides structural support and thermal stability, while insulating resist ensures complete burial of spaces between coil contact layers. This composite material strategy achieves both protrusion control and pore-free insulation.
3Manufacturing precision
If CMP processing is used to planarize upper surface of auxiliary yoke layer, then surface flatness is achieved, but resist smear occurs
Solution Approach 1:
The patent extracts the planarization function from the CMP process by using inherently flat inorganic insulating material layers. This eliminates the need for CMP processing that causes resist smear, while still achieving the required surface flatness for subsequent manufacturing steps.
Solution Approach 2:
The patent replaces the complex CMP processing step with a simpler inorganic insulating material deposition process. This substitution eliminates the harmful resist smear effect while maintaining surface flatness, using a more reliable and cleaner manufacturing approach.
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 configuration effectively suppresses heat-induced protrusion of the recording element and reduces resist smear, ensuring reliable operation and preventing damage to the recording medium.
Implementation Method 1
if the thin film coil generates heat, the insulating resist expands, which causes the recording element portion to protrude toward the surface that faces the recording medium
Implementation Method 2
the solenoid type thin film coil includes a lower coil wire group that has a plurality of coil wires formed below the magnetic material layer
Data Source
AI summary
A thin film magnetic head is provided. The thin film magnetic head includes an upper coil wire group and a lower coil wire group. Two columns of coil contact groups that are formed on both end portions of individual coil wires of the upper coil wire group and the lower coil wire group, connect both end portions of the coil wires. An insulating resist layer buries a space between coil contacts of the coil contact groups. An inorganic insulating layer buries a space between the two columns of coil contact groups. The upper coil wire group, the lower coil wire group, and the two columns of coil contact groups form a thin film coil that applies a magnetic recording field to the magnetic material layer. The insulating resist layer and the inorganic insulating layer are located at the same lamination height as the two columns of coil contact groups.