Semiconductor Carrier Structure for Thermal Mating Alignment
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Solution Overview
Problem
The assembly of semiconductor lighting modules is hindered by stress due to coefficient of thermal expansion (CTE) mismatch between VCSEL arrays and heat sinks or submounts, and the alignment of these components is labor-intensive.
Innovation Solution
A carrier structure comprising submounts and an alignment structure that mechanically couples them, allowing the submounts to approach each other during cooling and break if thermal stress exceeds a threshold, reducing alignment effort and accommodating CTE mismatch by using bridges and frames that weaken or vaporize during thermal mating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If VCSEL arrays are soldered to heat sink or submount, then thermal coupling is achieved, but stress is created due to CTE mismatch limiting maximum chip area
Solution Approach 1:
The patent divides the carrier structure into multiple sub carriers (first sub carrier, second sub carrier, etc.) that can be independently mounted on the heat sink. Each sub carrier can be optimally sized and positioned, allowing thermal coupling without excessive stress accumulation that would occur in a single large rigid carrier.
Solution Approach 2:
The patent introduces bridge structures with different material properties than the sub carriers themselves. These bridges have specific CTE characteristics that differ from both the sub carrier and heat sink materials, creating a gradient that locally manages stress distribution at the interfaces.
2Temperature
If VCSEL arrays are soldered to heat sink, then thermal management is improved, but alignment effort with optical elements increases
Solution Approach 1:
The sub carriers are pre-positioned and mechanically coupled to each other through bridge structures before final soldering to the heat sink. This preliminary arrangement establishes precise spatial relationships and alignment between VCSEL arrays and optical elements, so that when thermal mating occurs, the components remain properly aligned without requiring additional alignment operations.
Solution Approach 2:
The bridge structures serve as intermediary elements between sub carriers and the heat sink, and also between adjacent sub carriers. These bridges maintain fixed geometric relationships and facilitate automatic alignment through the mechanical coupling they provide during the assembly process.
3Strength
If bridges are designed to break during thermal mating, then stress relief is achieved, but mechanical coupling is lost
Solution Approach 1:
The bridge structures are designed with predetermined breaking points or weakened sections that will fail under excessive thermal stress. This beforehand cushioning allows the system to absorb and relieve stress through controlled bridge failure, preventing damage to the more critical sub carriers, VCSEL arrays, and heat sink while maintaining overall structural integrity through the remaining connected components.
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 simplifies the assembly of semiconductor lighting modules by reducing alignment effort and accommodating CTE mismatch, enabling efficient thermal mating and reducing mechanical stress, thus facilitating the use of larger chip areas and easier alignment of optical elements.
Implementation Method 1
The alignment structure is further adapted to compensate for the coefficient of thermal expansion of a material of the carrier being higher than the coefficient of thermal expansion of a material of the carrier structure by the sub carriers being enabled to approach to each other during a cooling phase of thermal mating
Implementation Method 2
the bridges are adapted to break during thermal mating the carrier structure to the carrier if thermal stress exerted on the bridges exceeds a threshold value
Data Source
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AI summary
The invention describes carrier structure (100, 200) for assembling a semiconductor lighting module, comprising at least two sub carriers (110, 210) and an alignment structure (120, 130, 230, 232) mechanically coupling the sub carriers (110, 210). The alignment structure (120, 130, 230, 232) is adapted such that the mechanical coupling to at least a part of the sub carriers (110, 210) disappears during thermal mating the carrier structure (100, 200) on a carrier (110, 250). The alignment structure (120, 130, 230, 232) is further adapted to compensate a coefficient of thermal expansion of a material of the carrier (110, 250) being higher than a coefficient of thermal expansion of a material of the carrier structure (100, 200). The invention further describes a semiconductor chip comprising such a carrier structure (100, 200) and a semiconductor lighting module comprising the carrier structure (100, 200) or the semiconductor chip. The invention finally describes a corresponding method of manufacturing a semiconductor lighting module. The invention enables assembling of semiconductor lighting modules by thermal mating with reduced alignment effort.