Isolated Heat Spreader Package for Dual-Sided Semiconductor Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor packages face challenges in efficiently dissipating heat, particularly in high voltage applications, which limits their power density and reliability, especially when integrating power stages and control dies in a single package.
Innovation Solution
The use of an exposed leadframe pad with a semiconductor die and a physically and electrically isolated heat spreader on the opposite side, facilitated by an electrically insulating material, enhances heat dissipation by allowing conductive cooling through both the leadframe pad and the heat spreader, thereby increasing power density and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a larger package size is used to increase the exposed leadframe pad area for better heat dissipation, then thermal handling capability is improved, but package size and complexity increase
Solution Approach 1:
The heat dissipation function is segmented into two independent paths: the leadframe pad and the heat spreader. This allows heat to be dissipated through multiple separate routes rather than relying on a single large package structure, resolving the contradiction between heat dissipation capability and package size.
Solution Approach 2:
The heat spreader extends the heat dissipation area to a different spatial dimension (the bottom surface of the package), rather than only expanding the leadframe pad area on the top surface. This utilizes the third dimension (vertical space) to increase thermal handling without increasing the package footprint.
2Temperature
If a heat spreader is added to improve heat dissipation, then thermal handling capability is improved, but device complexity increases
Solution Approach 1:
The heat spreader serves multiple functions simultaneously: it acts as a thermal conduction path for heat dissipation, provides electrical isolation from the semiconductor die, and serves as a mounting surface for the control die. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The electrically insulating material acts as an intermediary between the semiconductor die and the heat spreader, enabling thermal conduction while maintaining electrical isolation. This intermediary component allows the heat spreader to be integrated into the package without creating electrical conflicts, managing the complexity increase.
3Reliability
If the heat spreader is electrically isolated from the semiconductor die, then reliability is improved by preventing electrical interference, but thermal conduction efficiency may be reduced
Solution Approach 1:
The electrically insulating material is applied locally only where electrical isolation is needed (between the heat spreader and the semiconductor die), rather than throughout the entire heat spreader structure. This localized application maintains thermal conduction efficiency in the regions where electrical isolation is not required, while still achieving the necessary electrical isolation for reliability.
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 configuration effectively mitigates heat generated by high voltage power stages, improving the power density and reliability of integrated semiconductor packages, particularly in high voltage and high frequency applications.
Implementation Method 1
an electrically insulating material within the gap and in contact with the active side of the semiconductor die and the heat spreader
Implementation Method 2
Heat from the semiconductor die is dissipated through the electrically isolated heat spreader and the leadframe pad
Data Source
AI summary
A semiconductor package includes a metallic pad and leads, a semiconductor die attached to the metallic pad, the semiconductor die including an active side with bond pads opposite the metallic pad, a wire bond extending from a respective bond pad of the semiconductor die to a respective lead of the leads, a heat spreader over the active side of the semiconductor die with a gap separating the active side of the semiconductor die from the heat spreader, an electrically insulating material within the gap and in contact with the active side of the semiconductor die and the heat spreader; and mold compound covering the semiconductor die and the wire bond, and partially covering the metallic pad and the heat spreader, with the metallic pad exposed on a first outer surface of the semiconductor package and with the heat spreader exposed on a second outer surface of the semiconductor package.