CPP Magnetoresistive Head Thermal Management via Heat Dissipation Layer
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Solution Overview
Problem
CPP magnetoresistive heads generate excessive heat due to uniform current flow through all layers, leading to reduced MR ratio and poor heat dissipation efficiency, causing the magnetoresistive film to protrude from the air bearing surface.
Innovation Solution
Incorporating a high heat conductivity layer between the magnetic shield layers and the magnetoresistive film, along with a heat dissipation layer having high heat conductivity and low linear expansion coefficient, disposed at the back and sides of the magnetoresistive film, to efficiently dissipate heat while minimizing thermal expansion and protrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a CPP structure magnetoresistive head is used to achieve high sensitivity reading, then the read output is improved, but excessive heat is generated in the magnetoresistive film
Solution Approach 1:
A heat dissipation layer is introduced as an intermediary component between the magnetoresistive film and the surrounding structure. This layer acts as a thermal mediator that conducts heat away from the magnetoresistive film, reducing its temperature while maintaining the high sensitivity reading capability of the CPP structure.
Solution Approach 2:
The thermal conductivity parameter of the structure is changed by introducing a heat dissipation layer with high thermal conductivity. This parameter change enables efficient heat transfer from the magnetoresistive film to the heat dissipation layer, thereby controlling the temperature rise while preserving the read output performance.
2Power
If a high sense current is flowed through the magnetoresistive film to increase read output, then the signal strength is improved, but the heat generation increases and MR ratio decreases
Solution Approach 1:
The heat generated by the high sense current, which is normally a harmful effect reducing the MR ratio, is converted into a manageable parameter by introducing the heat dissipation layer. This layer captures and conducts away the heat, allowing the high sense current to be maintained for strong read output without the detrimental effect of temperature rise on the MR ratio.
3Stability of the object's composition
If insulating films are disposed on each side of the magnetoresistive film to provide structural support, then the device integrity is improved, but the heat dissipation efficiency deteriorates
Solution Approach 1:
Different regions of the structure are assigned different material properties: insulating films are maintained in regions where electrical isolation is needed, while a heat dissipation layer with high thermal conductivity is positioned in regions where heat removal is critical. This local differentiation of material quality allows simultaneous achievement of device integrity and heat dissipation efficiency.
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 solution effectively dissipates heat generated in the magnetoresistive film, maintaining a stable MR ratio and preventing protrusion from the air bearing surface, even at elevated temperatures, thus enhancing the read output and storage density.
Implementation Method 1
a heat dissipation layer having a high heat conductivity and a low linear expansion coefficient, the heat dissipation layer being disposed at the back in a device height direction of the magnetoresistive film
Implementation Method 2
in the CPP structure magnetoresistive head, since a sense current flows through the stacked plane of a magnetoresistive film, an identical current flows basically to all of the layers. That is, when a large sense current flows to an intermediate layer provided between two ferromagnetic layers which are an important part for generating the magnetoresistive effect, an identical current flows also to the anti-ferromagnetic layer of high electric resistivity to result in large heat generation.
Implementation Method 3
A magnetic recording device, for example, a hard disk drive, has gradually been expected to provide more storage capacity as the recent trend of the information society has demanded it. One way to increase the storage capacity of magnetic recording devices is to increase the recording density per unit area of the magnetic recording device, and improvement in techniques for increasing the sensitivity of a read device that utilizes the magnetoresistive effect
Data Source
AI summary
According to one embodiment, a CPP magnetoresistive head includes a magnetoresistive film comprising a free layer above a non-magnetic intermediate layer and a fixed layer below the non-magnetic intermediate layer, wherein the magnetoresistive film is between a lower magnetic shield layer and an upper magnetic shield layer. The CPP magnetoresistive head also includes a domain control film on each side of the magnetoresistive film, wherein a sense current flows through the magnetoresistive film between the upper magnetic shield layer and the lower magnetic shield layer. The CPP magnetoresistive head also includes a high heat conductivity layer, and a heat dissipation layer having a high heat conductivity and a low linear expansion coefficient, the heat dissipation layer being disposed at the back in a device height direction of the magnetoresistive film and on each side of the domain control film.