Intelligent Power Module Thermal Resistance Reduction
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Solution Overview
Problem
Conventional molded intelligent power modules (IPMs) for motor driving face challenges in reducing thermal resistance from junction-to-case (RthJC), which limits their application to heavy load motors with currents greater than ten amperes.
Innovation Solution
The design incorporates a reduced thermal resistance by using a direct bonded copper (DBC) type substrate with optimized layout and die supporting elements, along with a low voltage and high voltage IC, and a molding encapsulation that encloses MOSFETs and ICs, while reducing the number of leads and introducing conformal curved sides to enhance thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional insulated metal substrate (IMS) with two copper layers is used, then the manufacturing process is simpler, but the thermal resistance from junction-to-case (RthJC) is higher
Solution Approach 1:
The patent uses a direct bonded copper (DBC) substrate which combines copper layers with a ceramic or metal intermediate layer, creating a composite material structure that provides both mechanical support and superior thermal conduction pathways from the MOSFET junctions to the case, thereby reducing RthJC while maintaining manufacturability
Solution Approach 2:
The patent implements optimized die supporting elements with localized thermal management features, including thermally conductive pathways directly beneath each MOSFET die, ensuring that heat is efficiently extracted at the critical locations where it is generated, rather than relying on uniform thermal distribution
2Reliability
If three driving integrated circuits (ICs) are used, then the motor driving capability is sufficient, but the package size increases
Solution Approach 1:
The patent merges the functions of three separate driving ICs into a single integrated controller IC that can drive all six MOSFETs (three phases) through integrated control logic and output stages, thereby reducing the number of discrete components and minimizing the overall package footprint while maintaining full motor driving capability
Solution Approach 2:
The single controller IC performs multiple functions including PWM generation, dead-time control, fault detection, and protection circuits for all three motor phases, making it a universal control unit that replaces what would traditionally require three separate ICs, thus reducing package size without sacrificing functionality
3Reliability
If more leads are used for connecting ICs and MOSFETs, then the electrical connections are more robust, but the device complexity increases
Solution Approach 1:
The patent transitions from a planar lead arrangement to a three-dimensional internal wiring structure within the DBC substrate, where electrical connections are routed through vertical vias and embedded conductors beneath the surface, allowing multiple electrical connections to be made without increasing the external footprint or lead count, thus maintaining connection robustness while reducing device complexity
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 enables the IPM to effectively manage heat, allowing its use in heavy load motors with improved thermal efficiency and compact package size, facilitating the handling and manufacturing process.
Implementation Method 1
The IMS is usually clamped by two copper layers... reduction of RthJC of the present disclosure enables the IPM to be used for heavy load motors
Implementation Method 2
a molding encapsulation that encloses MOSFETs and ICs
Data Source
AI summary
An intelligent power module (IPM) has a first, second, third and fourth die supporting elements, a first, second, third, fourth, fifth and sixth transistors, a connection member, a low voltage IC, a high voltage IC, a plurality of leads and a molding encapsulation. The first transistor is attached to the first die supporting element. The second transistor is attached to the second die supporting element. The third transistor is attached to the third die supporting element. The fourth, fifth and sixth transistor s are attached to the fourth die supporting element. The low and high voltage ICs are attached to the connection member. The molding encapsulation encloses the first, second, third and fourth die supporting elements, the first, second, third, fourth, fifth and sixth transistors, the connection member and the low and high voltage ICs. The IPM has a reduced thermal resistance of junction-to-case (RthJC) compared to a conventional IPM.