Laser Die Heat Extraction Path With Thin Thermal Interface Layer
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Solution Overview
Problem
Current semiconductor packages face inefficiencies in heat extraction due to thick thermal pads, which lead to increased stress and temperature deltas between the IC die and housing, violating thermal specifications and potentially affecting the performance of high-power components like laser dies.
Innovation Solution
A semiconductor package design utilizing a thin (25-80 um) highly conductive thermal interface material, integrated heat spreader, ceramic carrier plate, and electrically conductive thermal gap pad to create an efficient heat extraction path without direct contact on the IC die, minimizing temperature deltas and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal pads are used to extract heat from the die, then heat conduction path is provided, but the thick bondline (5.00 to 700 um) reduces heat extraction efficiency
Solution Approach 1:
The patent changes the thickness parameter of the thermal interface material from the conventional thick bondline (5.00 to 700 um) to a thin bondline (5.00 to 50.0 um), specifically optimizing it to 25-80 micrometers for high thermal conductivity materials. This parameter change directly improves heat extraction efficiency by reducing the thermal resistance path while maintaining adequate mechanical compliance.
Solution Approach 2:
The patent employs composite material selection by using highly conductive thermal interface materials with thermal conductivity of 1.0 to 10.0 W/cm-K (such as indium, silver epoxy, or sintered graphite) combined with a ceramic carrier having matched CTE. This composite approach optimizes both thermal conduction and mechanical stress management simultaneously.
2Temperature
If thermal pads are compressed to provide heat conduction path, then heat extraction is enabled, but stress is put on the die that deteriorates performance
Solution Approach 1:
The patent optimizes the thickness parameter to 25-80 micrometers, which provides sufficient compliance to accommodate thermal expansion differences without transmitting excessive stress to the die, while still maintaining low thermal resistance. This precise thickness control balances heat extraction efficiency with stress mitigation.
Solution Approach 2:
The use of soft, compliant materials such as indium foil or sintered graphite provides mechanical compliance that absorbs thermal expansion stresses, protecting the die from stress-induced performance degradation while maintaining effective thermal conduction.
3Temperature
If conventional thermal pads are used, then heat extraction is provided, but the differing CTEs of PCB, die, thermal pads and housing create stress in the package
Solution Approach 1:
The patent uses a ceramic carrier with coefficient of thermal expansion (CTE) matched to the semiconductor die, creating a composite structure that minimizes CTE mismatch stress. The thin thermal interface material layer (25-80 um) of compliant material further accommodates residual thermal expansion differences, protecting the die from stress while maintaining effective heat extraction.
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 solution effectively reduces the temperature of the IC die and maintains a low temperature delta with the housing, ensuring thermal specifications are met and reducing stress on the die, thereby enhancing the performance and reliability of high-power components.
Implementation Method 1
a thermal interface material over the IC die, the thermal interface material having a thickness of approximately 25 to 80 um; an integrated heat spreader over the thermal interface material
Data Source
AI summary
A semiconductor package comprises a substrate and a ceramic carrier mounted to the substrate. An integrated circuit (IC) die is mounted to the ceramic carrier. A heat extraction path away from the IC die comprises: i) a thermal interface material over the IC die, the thermal interface material having a thickness of approximately 25 to 80 um; ii) an integrated heat spreader over the thermal interface material; iii) a ceramic carrier plate over the integrated heat spreader; and iv) an electrically conductive thermal pad between the ceramic carrier plate and a housing of the semiconductor package.