Multi-phase Half Bridge Driver Package with Stacked Transistors
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Solution Overview
Problem
Conventional multi-phase half bridge drivers have a large footprint, poor heat dissipation, and high inductance, leading to voltage spikes and electromagnetic interference due to their board-based implementation, which is inadequate for high-power, high-temperature applications like multi-phase brushless DC motors.
Innovation Solution
A semiconductor package design featuring stacked half bridges with metal leads embedded in a mold compound, providing improved heat dissipation and reduced inductance connections, along with bond wire connections to a controller die for efficient control and reduced EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional board-based implementation is used, then ease of manufacture is improved, but footprint area and heat dissipation performance worsen
Solution Approach 1:
The patent merges multiple components (power transistor dies, controller die, metal leads, and cooling features) into a single integrated semiconductor package. This consolidation eliminates the need for separate PCB mounting, reducing the overall footprint while maintaining manufacturability through standardized packaging processes.
Solution Approach 2:
The patent transitions from a two-dimensional PCB layout to a three-dimensional stacked architecture within the semiconductor package. Multiple power transistor dies are stacked vertically with metal leads connecting between layers, enabling high current handling in a compact volume and improving heat dissipation through vertical thermal paths.
2Ease of manufacture
If conventional board-based implementation is used, then ease of manufacture is improved, but heat dissipation capability worsens
Solution Approach 1:
The patent integrates cooling features directly into the semiconductor package structure, merging thermal management functionality with the electrical components. This eliminates the need for separate external cooling solutions and enables efficient heat dissipation through the package's metal leads and structured encapsulant.
Solution Approach 2:
The patent introduces a structured encapsulant as an intermediary material that provides both electrical insulation and thermal management. The encapsulant's structured design creates thermal pathways that facilitate heat dissipation from the power transistor dies while maintaining electrical isolation between components.
3Ease of manufacture
If board-based implementation with long connections is used, then ease of manufacture is improved, but inductance and EMI worsen
Solution Approach 1:
The patent merges the controller die and power transistor dies into a single integrated package with short internal connections. This eliminates the high-inductance external traces found in board-based implementations, reducing voltage spikes and EMI while maintaining manufacturability through standardized packaging processes.
Solution Approach 2:
The patent transitions from two-dimensional PCB traces to three-dimensional internal package connections. Metal leads are routed through the package structure with minimal length, and bond wires provide direct electrical pathways between dies, dramatically reducing loop area and inductance compared to external board connections.
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 results in a compact, efficient multi-phase half bridge driver with enhanced heat dissipation, reduced voltage spikes, and lower EMI, achieving system-level cost savings through reduced input filtering requirements.
Implementation Method 1
a mold compound in which each half bridge and each metal lead is embedded
Implementation Method 2
a separate first metal lead attached to a bottom side of the first power transistor die and to a top side of the second power transistor die
Implementation Method 3
generates significant heat that must be dissipated by the package
Data Source
AI summary
A semiconductor package includes a plurality of half bridge assemblies each including a metal lead, a first power transistor die attached to a first side of the metal lead, and a second power transistor die disposed under the first power transistor die and attached to a second side of the metal lead opposite the first side. Each metal lead has a notch which exposes one or more bond pads at a side of the second power transistor die attached to the metal lead. The semiconductor package also includes a controller die configured to control the power transistor dies. Each power transistor die, each metal lead and the controller die are embedded in a mold compound. Bond wire connections are provided between the controller die and the one or more bond pads at the side of each second power transistor die exposed by the notch in the corresponding metal lead.