Semiconductor Laser Submount Structure for Solder Creep Restraint
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Solution Overview
Problem
Existing light emitting devices face challenges in achieving a compact size while maintaining effective bonding and electrical connectivity between semiconductor laser elements and their submounts, which can lead to potential malfunctions due to solder creep and inadequate thermal management.
Innovation Solution
A light emitting device design featuring a submount with a specific lateral face configuration and bonding material protrusion, along with a manufacturing method that includes forming recesses and using a low-temperature metal paste for bonding, enhances bonding strength and reduces device size without compromising thermal radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a groove is provided on the substrate to restrain solder creep, then reliability is improved, but device size increases
Solution Approach 1:
The patent extracts the solder creep restraint function from the substrate groove and relocates it to the submount structure. By providing a lateral face on the submount that is separated from the mounting surface, the solder is restrained at the submount level rather than requiring substrate-level intervention, thus preventing solder creep without increasing substrate area.
Solution Approach 2:
The patent transitions from a two-dimensional substrate groove approach to a three-dimensional submount lateral face approach. The lateral face of the submount creates a physical barrier in the vertical dimension that restrains solder creep, eliminating the need for additional horizontal space that would be required by substrate grooves.
2Volume of moving object
If the submount is positioned closer to reduce device size, then volume is reduced, but thermal management deteriorates
Solution Approach 1:
The patent segments the submount into distinct functional surfaces: a lower face for bonding to the substrate, lateral faces for solder restraint and thermal radiation, and an upper face for mounting semiconductor elements. This segmentation allows each surface to be optimized for its specific function, including thermal management through the laterally-facing surfaces.
Solution Approach 2:
The patent applies local quality by providing lateral faces on the submount that are specifically oriented for thermal radiation. These laterally-facing surfaces are positioned to efficiently dissipate heat in horizontal directions, creating localized thermal management zones without requiring increased overall device volume.
3Strength
If bonding material is applied generously to ensure strong bonding, then bonding strength is improved, but solder creep resistance deteriorates
Solution Approach 1:
The patent introduces the submount lateral face as an intermediary structure between the bonding material and the solder. This lateral face acts as a physical barrier that prevents solder from creeping along the bonding material, allowing adequate bonding material to be used for strong bonding without compromising solder creep resistance.
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 achieves a smaller form factor with improved bonding and thermal management, reducing the risk of solder creep and enhancing electrical connectivity, thus ensuring reliable operation.
Implementation Method 1
sintering the paste material to form a bonding layer between the mounting surface of the base portion and the lower face of the submount
Implementation Method 2
sintering an electrically conductive paste material to form one or more electrically conductive members that are in contact with the one or more recesses
Data Source
AI summary
A light emitting device includes: at least one semiconductor laser element; a submount; and a base portion having a mounting surface. The submount includes: a first lateral face being located at a side of an exiting lateral surface of the semiconductor laser element, the first lateral face intersecting the upper face of the submount, and the first lateral face being above and separated from the mounting surface; a lower face being set back inside of the submount relative to an edge at which the upper face and the first lateral face intersect in a top view; and a second lateral face being located at the same side as the first lateral face and intersecting the lower face. A portion of a bonding material protrudes from the lower face and extends outward of an edge at which the lower face and the second lateral face intersect.