Center-Recessed Heat Sink for HAMR Head Touchdown Protection

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Solution Overview

Problem

Existing HAMR heads face challenges in achieving ultra-high recording densities due to thermal stability issues and difficulty in creating magnetic transitions with limited flux densities, leading to potential media damage during dynamic events like operating shocks and power-off.

Innovation Solution

Incorporating a thermally active bumper pad design with a center-recessed heat sink that generates protrusions to shift touchdown points away from sensitive areas, providing protection and adjusting contact points to enhance reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If HAMR head uses conventional heat sink design, then thermal management is achieved, but touchdown protection is insufficient and head-disk interference occurs

Engineering Contradiction:

Improvetouchdown protectionVSAvoidhead-disk interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent utilizes thermal expansion of the heat sink material to create a protrusion that acts as a bumper pad. The heat sink is designed with a recessed center region that allows differential thermal expansion, causing the outer regions to protrude toward the disk surface during thermal events, providing touchdown protection and preventing head-disk interference.

Inventive Principle:

Principle #37Thermal expansion

Solution Approach 2:

The patent converts the thermal energy that could cause harmful effects into a beneficial protective mechanism. The heat generated during operation or thermal events causes the heat sink to expand and form a protective bumper pad, turning potentially harmful thermal effects into a protective feature that prevents media damage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Stability of the object's composition

If heat sink is added to manage thermal effects, then thermal stability improves, but device complexity increases

Engineering Contradiction:

Improvethermal stabilityVSAvoidheat sink structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The heat sink serves multiple functions: it manages thermal effects during normal operation, creates touchdown protection through thermal expansion, and forms a protective bumper pad during thermal events. By integrating these multiple functions into a single component, the patent reduces overall device complexity while achieving thermal stability and protection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the thermal management function with the touchdown protection function into a single heat sink component. The heat sink is designed with specific geometric features (recessed center, outer regions) that allow it to perform both thermal conduction and mechanical protection functions, eliminating the need for separate protective structures.

Inventive Principle:

Principle #5Merging (Combining)

3Stability of the object's composition

If high coercivity media is used for ultra-high density recording, then data stability improves, but magnetic transition creation becomes difficult

Engineering Contradiction:

Improvedata stabilityVSAvoidmagnetic transition creation

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent changes the temperature parameter of the media during the writing process. By heating the media to reduce its coercivity temporarily, the write head can create magnetic transitions more easily. After writing, the media cools and coercivity increases, stabilizing the recorded data. This dynamic parameter change enables both ease of writing and data stability.

Inventive Principle:

Principle #35Parameter changes

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 design effectively protects the write head from touchdown and head-disk interference by shifting contact points, improving reliability and adjusting contact areas to prevent overcompensation and wear.

Implementation Method 1

a center-recessed heat sink that generates protrusions

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

thermally active bumper pad design with a center-recessed heat sink

Methodology Applied

Scientific EffectHeat sink: Heat Sink

Data Source

PatentUS20250378847A1Novel DFH Bulge by Heat Sink Design

Publication Date: 2025.12.11 SAE MAGNETICS (HK) LTD

AI summary

A PMR read/write head configured for heat assisted magnetic recording (HAMR), produces a thermally active bulge when a current is passed through a heater element formed on a centrally recessed heat sink mounted on a read shield. When the heater element is activated by a current, a bulge is formed by thermal expansion of the centrally recessed heat sink and symmetric pairs of bumper pads are formed. These thermally activated bumper pads act like symmetrically shaped nano-bumpers and provide enhanced touchdown (TD) protection to a reader (or writer) element. The PMR read/write head is mounted on a slider and the assembly is incorporated into a hard disk drive (HDD).