Optical Bonding of Light Source Unit and Slider in TMR Heads
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Solution Overview
Problem
The challenge in thermally-assisted magnetic recording is to align and bond a light source unit and a slider with high accuracy while maintaining the thermal stability of magnetic head elements, as conventional methods can lead to misalignment and degradation of the MR multilayer structure due to high temperatures during soldering.
Innovation Solution
A method involving a unit adhesion material layer made of Sn, Sn alloy, Pb alloy, or Bi alloy, which is melted using light transmitted through a substrate, allowing for precise alignment and bonding with higher strength and reduced thermal impact on the magnetic head elements, using active alignment and a reflective layer to enhance light absorption and minimize heat conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional soldering methods are used to bond the light source unit and slider, then bonding strength is achieved, but high temperature causes thermal degradation of the MR multilayer structure and misalignment
Solution Approach 1:
The patent changes the bonding method from conventional thermal soldering to optical bonding by using a laser beam to melt the adhesion material layer. This parameter change in the bonding mechanism allows achieving strong bonding at lower temperatures, avoiding thermal degradation of the MR multilayer structure while maintaining alignment precision.
Solution Approach 2:
The patent replaces the thermal field-based soldering process with an optical field-based bonding process. By using a laser beam to directly melt the adhesion material layer, the system substitutes thermal energy with optical energy, enabling bonding without the high temperatures that cause thermal degradation and misalignment in conventional methods.
2Strength
If high temperature soldering is applied to join the light source unit and slider, then bonding strength is improved, but the magnetic head elements suffer thermal stress and degradation
Solution Approach 1:
The patent replaces thermal soldering with optical bonding, using a laser beam to melt the adhesion material layer. This substitution eliminates the need for high temperature processing, thereby reducing thermal stress on the magnetic head elements while achieving sufficient bonding strength through the optical energy concentration.
Solution Approach 2:
The patent changes the energy form from thermal to optical for the bonding process. By using laser-induced melting of the adhesion material layer, the system achieves bonding at lower temperatures, preventing thermal stress and degradation of the magnetic head elements that would otherwise occur with conventional high-temperature soldering.
3Ease of manufacture
If conventional alignment and bonding methods are used, then manufacturing process is simple, but alignment accuracy is insufficient and manufacturing yield is reduced
Solution Approach 1:
The patent replaces conventional mechanical alignment and thermal bonding with optical bonding using a laser beam. The optical method provides superior alignment accuracy by enabling precise positioning during the bonding process itself, while the overall process remains integrated and manufacturable, improving yield without excessive complexity.
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 approach achieves high alignment accuracy and bonding strength with reduced thermal stress on the magnetic head elements, improving the manufacturing yield and reducing the risk of thermal degradation, thereby enhancing the performance of thermally-assisted magnetic recording heads.
Implementation Method 1
a unit adhesion material layer (solder layer) is melted by light that has entered the unit substrate
Implementation Method 2
causing light including a predetermined wavelength to enter the unit substrate to melt the unit adhesion material layer
Implementation Method 3
a reflective layer is provided on a surface of the unit substrate opposed to the slider substrate when joined to the slider
Implementation Method 4
the unit adhesion material layer containing a material selected from a group consisting of Sn (tin), Sn alloy, Pb (lead) alloy and Bi (bismuth) alloy
Data Source
AI summary
A method for manufacturing a thermally-assisted magnetic recording head is provided, in which a light source unit including a light source and a slider including an optical system are bonded. A unit substrate is made of a material transmitting light having a predetermined wavelength, and a unit adhesion material layer that contains Sn, Sn alloy, Pb alloy or Bi alloy is formed on the light source unit and/or the slider. The manufacturing method includes: aligning the light source unit and the slider in such a way that a light from the light source can enter the optical system and the unit adhesion material layer is sandwiched therebetween; and causing a light including the predetermined wavelength to enter the unit substrate to melt the unit adhesion material layer. The unit adhesion material layer melted by the light including the predetermined wavelength can ensure high alignment accuracy as well as higher bonding strength and less change with time.