3D Power Packaging with Focus on Embedded Passive Component and Substrate Technologies

Comprehensive report is the first to address higher power embeddable passives that will accelerate the development of higher density power sources using new, 3D disruptive packaging technologies

t APEC 2018, the PSMA Packaging Committee released a report titled "3D Power Packaging with Focus on Embedded Passive Component and Substrate Technologies." This is the third in a series of reports focused on using embedded substrate technology for building power sources. It is the first extensive study of embeddable passive components both available and in development for use in the power path of power sources. The report contains extensive research and product illustrations geared to an audience of technology executives and design engineers. The purpose of this Special Project is to provide an in-depth industry perspective on how currently available materials and processes can be best used for the creation of advanced high-efficiency, high-power-density power products.

The PSMA undertook this Special Project and created the 3D packaging report to address the pressing demands in the power industry to accelerate the development of higher density power sources. Miniaturization of passive components without compromising their power handling and efficiency, and their integration with actives has always been a key focus for power packaging. There is also an increasing trend to vertical or 3D package integration to address the performance issues by eliminating parasitics from large leads. Wide bandgap (WBG) devices, on the other hand, have become a key enabler to achieve high power densities and efficiency, owing to their many advantages over silicon. In particular, they enable operation at higher switching frequencies and temperatures with subsequent improvements in power density and efficiency. While SiC is presently the most mature WBG technology, production-ready for power train applications, GaN devices have recently gained importance with the GaN-on-Si technology, to reduce the cost. Embedding of WBG actives and passives, therefore, has become a very important technology in power applications to increase power density and efficiency along with miniaturization of power modules using Si devices for low power, and wide bandgap GaN and SiC devices for high power. Embedding gives lowest package inductance and enables co-integration of power systems and drivers in a single package with direct interconnection between gate driver circuits and switches with shortest interconnection length. This, however, leads to several process integration and reliability challenges that need to be systematically addressed. The challenges vary depend on the power of the system, power density, operation temperature and other criteria. The power electronics industry is actively pursuing solutions to address these challenges.

Georgia Tech Packaging Research Center, under contract from PSMA systematically surveyed the recent advances in passives, active embedding and 3D passive-active integration to generate this report, with emphasis on 3D power packaging enabled by advances in passive components and embedding of actives in power packages. A detailed literature study was conducted on key advances in embedded passive technologies and related topics. Emerging nanomaterials and processes are described for inductors, capacitors and resistors. Nanostructured materials provide additional degrees of freedoms in enhancing the properties to improve the performance metrics such as volumetric density and efficiency of the components. Key enabling building-blocks are described for each technology. The manufacturing challenges are also highlighted in advancing the components to improve performance. Industry leaders were surveyed to get the recent technology advances in each category. Roadmaps are projected for passive component advances and active embedding technologies.

Passive components, substrates and packaging technologies are categorized as follows:

1. Magnetic materials are classified into three categories: a) low-frequency, high-power magnetics such as those used in isolated DC-DC converters, b) medium-frequency, medium-power inductors used in ultra-thin or embedded inductors, c) high-frequency magnetics used in integrated power module applications.
2. Similarly, capacitors are classified into: a) formed thin-film capacitors for high-frequency decoupling, b) high-surface area silicon trench, sintered porous tantalum capacitors or etched Al foil capacitors, c) inserted ultra-thin MLCCs, and d) high-voltage, high-temperature capacitors.
3. Resistors are classified into thickfilm and thinfilm resistors and the key materials and process advances in each class are highlighted.

The trends and roadmaps in 3D power packaging are also described in three categories: low power (1-100 W), medium power (100-1000 W) and high power (10-100 kW). Integration in each category is classified into lead-frame-based, substrate-embedding based, and traditional ceramic substrates. Active embedding with panel- scale substrate manufacturing is also reviewed in detail. Recent innovations in substrate materials and associated reliability challenges such as via cracking, dielectric cracking or electric breakdown are highlighted. Advances in die-attach solutions with sintered nanocopper are reviewed, highlighting the evolution of low-stress sintered copper-based die-attach solutions.

Co-chairs of the PSMA Packaging Committee, Ernie Parker of Crane Aerospace & Electronics and Brian Narveson of Narveson Consulting, described the report as "the first comprehensive document to discuss the challenges companies will face to implement embedded passives in 3D power packaging to create the significantly higher power densities.

The PSMA report on 3D packaging was provided free of charge to PSMA Regular and Associate Company members.  Additional copies may be purchased at the member price of $290. PSMA Affiliate members may also purchase the report for $290. The report is available to non-members for purchase on the PSMA website (www.psma.com/publications) for the price of $3,490. 

Provided by the PSMA Packaging Committee.

Brian Narveson Co-chairman

Ernie Parker Co-chairman

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