Power Module Package With Magnetic Mold Compound Isolation
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Solution Overview
Problem
Conventional packaged power modules face high production costs due to the expense of discrete inductors, particularly those with stilts for 3D stacking, and reliability concerns arise from the use of magnetic mold compounds with high electrical conductivity in contact with silicon power FETs.
Innovation Solution
The use of lower cost inductor coils with a magnetic mold compound (MMC) and a conformal dielectric coating to electrically isolate active surfaces, enabling the integration of MMC with silicon power FETs while reducing leakage and allowing for efficient inductor formation and improved EMI shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If magnetic mold compound (MMC) is used to encapsulate the package, then inductor formation efficiency and EMI shielding are improved, but electrical leakage occurs due to high electrical conductivity of MMC contacting silicon power FETs
Solution Approach 1:
A conformal dielectric coating is applied as an intermediary layer between the MMC and the silicon power FETs. This coating acts as a mediator that allows the MMC to provide its magnetic and EMI shielding functions while preventing direct electrical contact that would cause leakage. The dielectric material bridges the gap between the magnetic requirements and electrical isolation requirements.
Solution Approach 2:
The encapsulation structure is segmented into multiple functional layers: the MMC provides magnetic properties and EMI shielding, while the conformal dielectric coating provides electrical isolation. This segmentation allows each material to perform its specific function without interfering with the other, resolving the contradiction between magnetic efficiency and electrical leakage prevention.
2Ease of operation
If conventional discrete inductors with stilts are used for 3D stacking, then inductor functionality is achieved, but production cost increases significantly
Solution Approach 1:
The inductor is merged with the MMC material itself. Instead of using separate discrete inductor components with stilts that need to be assembled, the magnetic mold compound is formulated to provide both the structural encapsulation and the inductive function. This integration eliminates the need for expensive custom inductors and simplifies the manufacturing process while maintaining 3D stacking capability.
Solution Approach 2:
The MMC serves multiple functions simultaneously: it provides structural encapsulation, magnetic properties for inductor formation, EMI shielding, and electrical isolation (when combined with the dielectric coating). This multi-functionality replaces the need for separate discrete inductor components, reducing production cost while maintaining functionality.
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 approach reduces production costs, enhances power efficiency, and provides a wide operating voltage range (5V-100V) while ensuring reliable operation by isolating the MMC from active surfaces, thus addressing both cost and reliability issues.
Implementation Method 1
The MMC provides both the required magnetic medium for high efficiency inductor formation
Implementation Method 2
applying a conformal coating of an electrically insulating (dielectric) material on a top side of the package to electrically isolate all active surfaces including on the die and the traces on the top surface of the package substrate from the MMC
Data Source
AI summary
A semiconductor package includes a package substrate having a top surface including traces and bonding features. There is at least one semiconductor die including a substrate having a semiconductor surface including circuitry electrically connected to bond pads mounted on the bonding features, and at least one inductor coil mounted with a first contact and a second contact that are positioned on the bonding features beyond the semiconductor die including a portion of the inductor over the semiconductor die. There is a dielectric coating on and within the inductor coil, on the semiconductor die, on the traces, and on the bonding features. A magnetic mold compound having magnetic particles and a dielectric material encapsulates the semiconductor die, the inductor, and the dielectric coating.