Metal-Embedded Photonic Module for Low-Stress Chip Heat Spreading
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Solution Overview
Problem
Existing photonic modules face challenges in effectively integrating high-power optoelectronic chips with a heat spreader, as prior art methods involve high-temperature and high-force bonding processes, leading to thermal and mechanical stress, and are incompatible with edge-coupled or edge-emitting devices that generate substantial heat.
Innovation Solution
A photonic module design where optoelectronic chips are integrated with electro-formed metal heat spreaders on opposing sides, allowing for direct heat conduction and reduced thermal resistance, with the metal heat spreader also serving as an electrical path and potentially incorporating coolant fluid chambers for enhanced thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature bonding process is used to attach chip to heat spreader, then bonding strength is improved, but thermal and mechanical stress increases degrading chip reliability
Solution Approach 1:
The patent introduces an intermediary material layer between the chip and heat spreader that enables bonding at lower temperatures. This intermediate layer acts as a buffer that reduces thermal and mechanical stress transmission to the chip, thereby maintaining bonding strength while protecting chip reliability during the attachment process.
Solution Approach 2:
The patent changes the bonding temperature parameter from high temperature to lower temperature by using alternative bonding methods or materials. This parameter change resolves the contradiction by achieving adequate bonding strength without subjecting the chip to high-temperature stress that would degrade its reliability.
2Adaptability or versatility
If dielectric heat spreader material is used to enable separate electrical contacts, then electrical functionality is improved, but thermal conductivity decreases increasing thermal resistance
Solution Approach 1:
The patent segments the heat spreader structure into multiple regions with different materials or functions. Certain areas use dielectric materials to provide electrical isolation for separate contacts, while other areas use high-thermal-conductivity materials to maintain efficient heat transfer. This segmentation allows the system to achieve both electrical functionality and thermal performance simultaneously.
Solution Approach 2:
The patent applies different material properties to different locations of the heat spreader. Local regions require electrical isolation are made dielectric, while regions prioritized for heat conduction use high-thermal-conductivity materials. This local differentiation resolves the contradiction by optimizing both electrical and thermal properties where needed.
3Loss of energy
If metal heat spreader material is used to achieve high thermal conductivity, then heat conduction is improved, but coefficient of thermal expansion mismatch increases causing stress
Solution Approach 1:
The patent uses composite material structures that combine metals with high thermal conductivity and materials with thermal expansion coefficients matched to the chip. This composite approach allows the heat spreader to achieve high thermal conductivity while the matched thermal expansion properties reduce stress and maintain compositional stability during temperature changes.
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 design minimizes thermal interfaces, reduces thermal resistance, and maintains chip reliability by avoiding high-temperature bonding, enabling precise optical alignment and improved electrical-to-optical conversion efficiency for high-power optoelectronic devices.
Implementation Method 1
allowing for direct heat conduction and reduced thermal resistance
Implementation Method 2
An outer frame is also placed onto the carrier wafer. This outer frame defines the regions to be filled by the electro-formed metal. The assembly then undergoes an electro-forming process in which the region between the chips located within a section defined by the outer frame is filled by an electroplated metal such as copper.
Data Source
AI summary
A photonic module and a method of making same, the module having one or more optoelectronic chips, such as a laser diode typically having six sides, with each optoelectronic chip having two opposing sides (a first side and a second side) abutting and electrically connected to metal regions (preferably electro-formed), the two metal regions are physically distinct and electrically separate from each other, the two electro-formed metal regions serving, in use, as heat spreaders for conducting heat away from the optoelectronic chip.