Integrated Power Module Thermal Slug Design
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Solution Overview
Problem
Current multi-chip power module packaging methods face challenges in achieving both improved electrical isolation and thermal conductivity, with direct bonded copper substrates being costly and limited in design, leadframe technology being unsuitable for coplanar multi-chip structures, and laminate PCB technology having low thermal performance due to unequal electrical potentials.
Innovation Solution
An integrated power module structure featuring a substrate with a bottom drain pad for the depletion mode device and an enhancement mode device footprint-sized cavity, filled with a thermally conductive and electrically insulating slug to create an efficient thermal path, ensuring improved electrical isolation and thermal conductivity while maintaining a conventional three-lead external topology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If direct bonded copper (DBC) substrates are used, then thermal conductivity is improved, but cost and design complexity increase
Solution Approach 1:
The patent applies local quality by providing high thermal conductivity only where needed (under the power devices through the slug) while using standard PCB materials elsewhere. The thermally conductive slug is strategically positioned to create a thermal pathway from the power devices to the heatsink, concentrating thermal management resources where they are most needed rather than requiring the entire substrate to have high thermal conductivity.
Solution Approach 2:
The patent uses composite materials by combining standard PCB substrate materials with a separate thermally conductive slug (such as copper or aluminum). This hybrid approach allows the benefits of high thermal conductivity materials to be integrated into a conventional PCB structure, achieving improved thermal performance without requiring the entire substrate to be made from expensive high-performance materials like DBC.
2Ease of manufacture
If laminate PCB technology is used, then cost and integration flexibility are improved, but thermal performance deteriorates
Solution Approach 1:
The patent introduces a thermally conductive slug as an intermediary element between the power devices and the heatsink. This slug acts as a thermal bridge, mediating heat transfer from the devices through the PCB substrate to the external heatsink, thereby enhancing thermal performance without requiring the entire PCB structure to be redesigned with high-performance thermal materials.
3Reliability
If electrical isolation is improved, then safety is improved, but thermal conductivity path is restricted
Solution Approach 1:
The patent segments the thermal and electrical pathways by using a thermally conductive but electrically insulating slug. This segmentation allows the thermal pathway to be optimized independently from the electrical isolation requirements, enabling heat to flow efficiently from the power devices through the slug while maintaining proper electrical isolation between different potential zones.
Solution Approach 2:
The patent changes the material parameters of the slug to achieve the desired combination of properties. By selecting materials with high thermal conductivity and high electrical resistivity (such as certain ceramics or electrically insulating metals), the patent optimizes the thermal-to-electrical conductivity ratio, allowing efficient heat transfer while maintaining electrical isolation.
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 prevents accidental on-state conditions in depletion mode devices during gate signal loss and enhances thermal management by establishing efficient thermal paths between devices, addressing the limitations of existing packaging methods.
Implementation Method 1
A thermally conductive and electrically insulating slug substantially fills the cavity to provide a higher efficient thermal path between the enhancement mode device and the bottom drain pad
Data Source
AI summary
An integrated power module having a depletion mode device and an enhancement mode device that is configured to prevent an accidental on-state condition for the depletion mode device during a gate signal loss is disclosed. In particular, the disclosed integrated power module is structured to provide improved isolation and thermal conductivity. The structure includes a substrate having a bottom drain pad for the depletion mode device disposed on the substrate and an enhancement mode device footprint-sized cavity that extends through the substrate to the bottom drain pad. A thermally conductive and electrically insulating slug substantially fills the cavity to provide a higher efficient thermal path between the enhancement mode device and the bottom drain pad for the depletion mode device.