SOI Die Bump-on-Leadframe Thermal Path
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Solution Overview
Problem
The thermal insulation properties of silicon-on-insulator (SOI) semiconductor dice lead to heat being trapped, causing temperatures to rise unacceptably and potentially damaging the devices, as the insulating layer prevents effective heat transfer from the active layer to the leads.
Innovation Solution
A semiconductor package design where the SOI die is oriented in a bump-on-leadframe manner with solder or metal bumps connecting the active layer to the leads, creating thermal paths for heat transfer to a printed circuit board, and optionally using thermal islands and heat slugs to enhance heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating layer is used in SOI die to provide electrical insulation, then electrical insulation between devices is improved, but heat transfer from the active layer is blocked causing thermal problems
Solution Approach 1:
The patent segments the SOI die structure by dividing it into multiple separate dies, each with its own handle layer and active layer. This segmentation allows heat to be dissipated from each individual die rather than being trapped in a single large die with an insulating layer, thus resolving the thermal problem while maintaining electrical insulation through the handle layers of individual dies.
Solution Approach 2:
The patent introduces an intermediary thermal path by mounting the SOI die on a leadframe with thermal coupling. The leadframe acts as a thermal intermediary that conducts heat away from the die's back surface, providing an alternative heat dissipation route that does not interfere with the electrical insulation function of the insulating layer.
2Reliability
If the SOI die is mounted via the handle layer to leads, then electrical connection is established, but thermal path is blocked by the insulating layer
Solution Approach 1:
The patent inverts the conventional mounting approach by mounting the SOI die on its back surface (handle layer) to the leadframe, rather than mounting it on the front surface. This inversion creates a direct thermal path from the back of the die through the leadframe to the PCB, allowing heat to escape from the mounting interface itself while the electrical connections are maintained through the die structure.
Solution Approach 2:
The patent adds a thermal dissipation dimension by utilizing the back surface of the die for thermal coupling to the leadframe. This creates a three-dimensional thermal management solution where heat can flow vertically through the leadframe while electrical connections are maintained through the die's front surface, separating the thermal and electrical pathways in different spatial dimensions.
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 significantly improves heat transfer capabilities, allowing for the efficient removal of heat generated by semiconductor devices, thereby preventing damage and ensuring both electrical and thermal stability of the SOI dice.
Implementation Method 1
a solder or other metal bump connecting a contact pad at a surface of the active layer with the lead... This forms a thermal path through which heat generated in the active layer may readily be transferred to a printed circuit board
Data Source
AI summary
Thermal transfer from a silicon-on-insulator (SOI) die is improved by mounting the die in a bump-on-leadframe manner in a semiconductor package, with solder or other metal bumps connecting the active layer of the SOI die to metal leads used to mount the package on a printed circuit board or other support structure.