Laser Diode Submount Bar Bonding Residual Stress Reduction
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Solution Overview
Problem
The existing manufacturing methods for laser diode units generate residual stress in the solder member and laser diode during bonding, which can lead to positional inaccuracies and reduced efficiency in thermally-assisted magnetic recording heads, where high precision is required.
Innovation Solution
A method involving a submount bar with integrated solder members, where one solder member is locally heated and melted while applying a pressing load to bond the laser diode, and subsequently, the adjacent solder member is heated to soften without melting, reducing residual stress and maintaining positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used to bond laser diode to submount, then bonding is achieved, but residual stress is generated in solder member and laser diode causing positional inaccuracies
Solution Approach 1:
The patent applies preliminary action by heating and softening the solder member before the bonding process to reduce residual stress generation. The method involves pre-heating the submount to a temperature that softens the solder member (but below melting point) before applying the laser diode and pressing load, thereby allowing the solder to conform better and reduce stress during subsequent cooling and bonding.
Solution Approach 2:
The patent changes the temperature parameter of the solder member during the bonding process. By controlling the heating temperature to soften the solder without melting it, and then controlling the cooling rate, the patent modifies the physical state and mechanical properties of the solder to minimize residual stress while maintaining bonding integrity.
2Strength
If pressing load is applied to bond laser diode to solder member, then bonding strength is achieved, but residual stress is generated causing positional inaccuracies
Solution Approach 1:
The patent changes the temperature parameter of the solder member during the bonding process. By controlling the heating temperature to soften the solder without melting it, and then controlling the cooling rate, the patent modifies the physical state and mechanical properties of the solder to minimize residual stress while maintaining bonding integrity.
3Reliability
If solder member is heated to melt for bonding, then bonding is achieved, but residual stress is generated in solidified solder
Solution Approach 1:
The patent applies preliminary action by heating and softening the solder member before the bonding process to reduce residual stress generation. The method involves pre-heating the submount to a temperature that softens the solder member (but below melting point) before applying the laser diode and pressing load, thereby allowing the solder to conform better and reduce stress during subsequent cooling and bonding.
Solution Approach 2:
The patent changes the temperature parameter of the solder member during the bonding process. By controlling the heating temperature to soften the solder without melting it, and then controlling the cooling rate, the patent modifies the physical state and mechanical properties of the solder to minimize residual stress while maintaining bonding integrity.
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 effectively reduces residual stress in both the solder member and laser diode, ensuring high positional accuracy and improved bonding, thereby enhancing the reliability and performance of laser diode units in thermally-assisted magnetic recording heads.
Implementation Method 1
a third step melting the solder member by heating the solder member at a temperature higher than a melting point of the solder member while the pressing load is being applied
Implementation Method 2
a fourth step softening the solidified solder member by heating the solder member at a temperature lower than the melting point of the solder member after the pressing load has been removed
Implementation Method 3
thereafter, bonding the laser diode to the submount by cooling and solidifying the solder member
Data Source
AI summary
A manufacturing method of laser diode unit of the present invention includes steps: placing a laser diode on top of a solder member formed on a mounting surface of a submount, applying a pressing load to the laser diode and pressing the laser diode against the solder member, next, melting the solder member by heating the solder member at a temperature higher than a melting point of the solder member while the pressing load is being applied, and thereafter, bonding the laser diode to the submount by cooling and solidifying the solder member, thereafter, removing the pressing load, and softening the solidified solder member by heating the solder member at a temperature lower than the melting point of the solder member after the pressing load has been removed, and thereafter cooling and re-solidifying the solder member.