Light Source Unit With Dual Electrode Layers For TAMR Heads
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Solution Overview
Problem
The challenge in thermally-assisted magnetic recording is to provide a light source with high output intensity within a magnetic recording head while maintaining mechanical stability and reducing production costs, as existing solutions face issues with mechanical shock, manufacturing yield, and the need for precise alignment and high-accuracy optical components.
Innovation Solution
A light source unit is designed with a laser diode integrated onto a unit substrate, featuring a unique electrode configuration that allows for bonding without protrusion, enabling high light use efficiency and reduced weight, and is mounted on the slider's back surface opposite to the medium surface, avoiding direct mechanical impact and simplifying manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a laser diode is mounted on the back surface of a slider with conventional electrode configuration, then the light source can be integrated into the magnetic recording head, but the electrode structure requires additional space that increases the unit substrate area and complicates the manufacturing process
Solution Approach 1:
The patent merges the first electrode and second electrode into a single unit electrode structure. The unit electrode is formed as one continuous conductive layer that serves both functions: providing electrical connection to the laser diode and acting as an electrode for light emission. This integration eliminates the need for separate electrode structures and reduces the overall substrate area required.
Solution Approach 2:
The unit electrode performs multiple functions simultaneously: it serves as the electrical connection terminal for the laser diode, acts as one of the light-emitting electrodes, and provides structural support. This multi-functionality reduces the number of separate components needed and simplifies the overall device architecture.
2Power
If the light source is disposed inside the head with high output intensity, then thermally-assisted magnetic recording can be performed effectively, but the mechanical shock resistance becomes problematic due to the fragile nature of laser diodes
Solution Approach 1:
The patent separates the light source generation function from the light emission function by using a non-contact coupling mechanism. The unit electrode generates light through electroluminescence, and this light is coupled to the magnetic recording medium through a non-contact optical coupling structure. This segmentation allows the fragile laser diode to be positioned away from the high-stress areas while still achieving effective heating of the magnetic medium.
Solution Approach 2:
The patent introduces an optical coupling medium or field as an intermediary between the unit electrode and the magnetic recording medium. This intermediary allows energy transfer (light) to occur without direct mechanical contact, protecting the laser diode from mechanical shock while maintaining effective thermal assistance for magnetic recording.
3Manufacturing precision
If precise alignment and high-accuracy optical components are used to maintain high light use efficiency, then the optical system performance is improved, but the production cost increases and manufacturing yield decreases
Solution Approach 1:
The unit electrode structure is designed to self-align with the optical system components through its geometric configuration and bonding structure. The integrated electrode design provides inherent alignment features that guide the positioning of optical components during assembly, eliminating the need for complex external alignment mechanisms and reducing manufacturing complexity.
Solution Approach 2:
The patent optimizes the geometric parameters of the unit electrode and optical coupling structure to maximize light use efficiency through design rather than precise assembly. By carefully selecting the dimensions, shapes, and positions of the electrode and optical components, the system achieves high efficiency with relaxed alignment tolerances, thereby improving manufacturing yield.
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 enhances the thermal stability of magnetization, improves recording density, reduces production costs, and maintains high light use efficiency without requiring sophisticated alignment technologies or expensive facilities, thereby increasing the manufacturing yield and reducing the per-head-chip cost.
Implementation Method 1
a light source including two electrode layers and a light-emission center that is located in a light-emitting surface adjacent to each of the two electrode layers
Implementation Method 2
an optical system that is provided in an element-integration surface of a slider substrate and propagates a light for thermal assist
Implementation Method 3
a magnetic recording medium formed of a magnetic material with a large energy KU is used so as to stabilize the magnetization, then anisotropic magnetic field of a portion of the medium, where data is to be written, is reduced by heating the portion
Implementation Method 4
just after that, writing is performed by applying write field to the heated portion
Data Source
AI summary
Provided is a light source unit the weight of which can be reduced while ensuring power supply to the light source. The light source is configured to form a thermally-assisted magnetic recording head by being joined with a slider including an optical system that propagates light for thermal assist. The light source unit comprises: a unit substrate including a joining surface that faces an power-supply electrode of the slider; a first electrode provided on the joining surface; a second electrode provided on a source-installation surface and electrically connected to the first electrode; and a light source that includes two electrode layers and a light-emission center located in a light-emitting surface. The first and second electrodes eliminate the provision of a terminal electrode for light source on the source-integration surface. As a result, the weight of the light source unit can be reduced.