Interposer Heat Sink Layout for GaN Power Converter Hotspots
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Solution Overview
Problem
High-density Switched-Mode Power Supply (SMPS) modules using GaN transistors generate excessive heat, which is poorly dissipated through traditional heat sinks and PCBs, leading to potential damage from localized hotspots due to the insulating properties of PCB materials.
Innovation Solution
Integration of interposer heat sinks that conduct both heat and electrical signals directly into the system PCB, using metal traces and vias to efficiently dissipate heat while maintaining electrical connectivity, thereby reducing hotspot formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If GaN transistors are used to increase power current density, then productivity and power density are improved, but temperature increases and thermal management becomes more difficult
Solution Approach 1:
The patent introduces an interposer substrate as an intermediary component between the GaN transistor package and the PCB. This interposer serves as a thermal mediator by incorporating heat sinks that conduct heat away from the transistor package leads before they reach the PCB, preventing hotspot formation while maintaining the high power current density capability of GaN devices
Solution Approach 2:
The patent segments the thermal management function by separating it from the traditional PCB-based heat dissipation approach. Instead of relying solely on the PCB to dissipate heat, the solution divides the thermal path into distinct segments: the package leads, the interposer heat sinks, and the PCB, allowing each component to handle thermal management in a specialized manner
2Temperature
If heat sinks are attached directly to transistor packages, then heat dissipation is improved, but electrical connectivity and signal integrity are compromised
Solution Approach 1:
The patent merges the electrical interconnection function with the thermal management function by integrating heat sinks directly into the interposer substrate that also provides electrical connectivity. This allows the same structural component to simultaneously conduct electricity and dissipate heat, eliminating the need to choose between electrical connectivity and thermal management
Solution Approach 2:
The interposer substrate is designed as a multi-functional component that performs both electrical interconnection and thermal management duties. The heat sinks are integrated into the interposer structure, allowing a single component to serve multiple functions: providing electrical pathways for signal transmission and conducting heat away from the transistor packages
3Ease of manufacture
If PCB materials are used for heat dissipation, then ease of manufacture is improved, but heat conduction capability deteriorates due to insulating materials
Solution Approach 1:
The patent employs composite material structures in the interposer substrate, combining materials with high thermal conductivity (such as metal heat sinks) with the PCB substrate material. This composite approach allows the system to maintain the manufacturing advantages of standard PCB processes while introducing materials that excel at heat conduction, thereby overcoming the thermal limitations of pure PCB-based heat dissipation
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 solution effectively dissipates heat generated by GaN transistors, maintaining cooler temperatures and preventing damage by utilizing highly conductive metal interposer heat sinks with large surface areas for heat dissipation.
Implementation Method 1
heat sinks integrated into the electrical signal paths between the power-convert transistors and the system PCB... efficiently dissipate this heat using a metal heat sink
Implementation Method 2
dissipate the heat from the heat sinks... large surface areas for heat dissipation
Implementation Method 3
dissipate this heat using a metal heat sink... large surface areas for heat dissipation
Data Source
AI summary
A power-converter module has a switching Printed Circuit Board (PCB) with power transistors that generate heat. Ground, an input power supply, and an output power supply to the power transistors connect through metal traces on the switching PCB directly to interposer heat sinks that are soldered between the switching PCB and a system PCB. The metal traces and interposer heat sinks carry both supply or ground currents and heat away from the power transistors. These power and ground currents continue from the interposer heat sinks to the system PCB through direct solder joints between the system PCB and the interposer heat sinks. An interposer PCB has a same thickness as the interposer heat sinks and carries control signals from the system PCB to the switching PCB, bypassing the interposer heat sinks. The interposer heat sinks have an interposer portion soldered between the PCBs and fins beyond the switching PCB footprint.