Embedded Die Heat Spreader With Insulator Layer for Crack-Free Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermal management in embedded die packaged devices is challenging due to heat generation from high power components like gallium nitride transistors, which can lead to cracking from coefficient of thermal expansion mismatch and increased thermal resistance with traditional heat spreader designs.
Innovation Solution
Incorporating a thermally conductive insulator layer between the semiconductor die and the metal plate, providing thermal coupling while maintaining electrical isolation and reducing parasitic inductance, thus facilitating effective heat removal and minimizing mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thick metal plate is directly connected to an embedded die to facilitate heat removal, then heat dissipation is improved, but coefficient of thermal expansion mismatch causes cracking in the embedded die through thermal cycling
Solution Approach 1:
A compliant layer is introduced between the thick metal plate and the embedded die to act as a stress-absorbing intermediary. This layer has a coefficient of thermal expansion intermediate between that of the metal plate and the die, and lower mechanical strength than both, allowing it to deform and absorb thermal expansion stresses during thermal cycling, thereby preventing cracking in the embedded die while still enabling effective heat removal through the thick metal plate.
2Reliability
If copper posts are provided between the embedded die and the metal plate to reduce mechanical stress, then cracking is reduced, but the effective thermal contact area is reduced, increasing thermal resistance
Solution Approach 1:
Instead of using discrete copper posts that create point contacts and increase thermal resistance, a continuous compliant layer is used as an intermediary between the metal plate and embedded die. This layer provides both mechanical stress relief through its low mechanical strength and high thermal contact area through its continuous coverage, simultaneously addressing both reliability and thermal performance concerns.
Solution Approach 2:
The mechanical strength parameter of the intermediate layer is deliberately set lower than both the metal plate and the embedded die, allowing it to yield and absorb thermal stresses. This parameter change enables the layer to function as a stress-relief mechanism while maintaining good thermal contact, avoiding the thermal resistance penalty associated with copper posts.
3Reliability
If the thickness of the metal plate is reduced to decrease thermal expansion stress, then mechanical stress is reduced, but thermal resistance increases and heat removal capability is reduced
Solution Approach 1:
The compliant layer serves as a stress-absorbing intermediary that allows the use of a thick metal plate for effective heat removal without suffering from the thermal expansion stress problems. The layer deforms during thermal cycling to accommodate the differential thermal expansion between the thick metal plate and the embedded die, enabling the plate to remain thick for optimal thermal performance while the intermediate layer protects against stress-induced cracking.
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 enhances heat dissipation, reduces thermal resistance, and mitigates cracking, enabling high-frequency operation and improved mechanical stability in embedded die packages.
Implementation Method 1
a thermally conductive insulator layer having a first side over and thermally coupled to a side of the semiconductor die, and a metal plate on an opposite second side of the thermally conductive insulator layer
Data Source
AI summary
A method of fabricating an electronic device includes forming an embedded die frame having a cavity and a routing structure, a semiconductor die in the cavity with a gallium nitride layer on the routing structure, and a heat spreader having a thermally conductive insulator layer and a metal plate, the thermally conductive insulator layer having a first side that faces the embedded die frame and an opposite second side that faces away from the embedded die frame, with a portion of the first side of the thermally conductive insulator layer extending over a side of a silicon substrate of the semiconductor die, and the metal plate on the second side of the thermally conductive insulator layer.