US 11888392

US Patent 11888392: High Speed, Efficient SiC Power Module

Title: High speed, efficient sic power module

Assignee: Wolfspeed Inc.

Inventors: Mrinal K. Das, Adam Barkley, Henry Lin, Marcelo Schupbach

Filing Date: April 17, 2020

Issue Date: January 30, 2024

Abstract:
A power converter module is disclosed, comprising an active metal braze (AMB) substrate, power converter circuitry, and a housing. The AMB substrate features an aluminum nitride base layer with first and second conductive layers on its opposite surfaces. The power converter circuitry, which includes multiple silicon carbide (SiC) switching components, is coupled via the first conductive layer. The housing encapsulates the power converter circuitry and the AMB substrate. This design, utilizing an AMB substrate with an aluminum nitride base layer, aims to significantly improve the thermal dissipation characteristics and structural integrity of the power converter module.

Plain-Language Overview of Independent Claims:

Independent Claim 1:
This claim describes a power converter module that includes:

• A housing.
• A substrate located inside the housing, which has a base layer and a conductive layer on one of its surfaces.
• Power converter circuitry built on the substrate, containing at least two silicon carbide (SiC) switching components connected to each other through the conductive layer.
  Crucially, this power converter module is explicitly stated to not include a baseplate.

Independent Claim 15:
This claim outlines a power converter module featuring:

• A housing.
• A substrate that consists of a base layer, a first conductive layer on its first surface, and a second conductive layer on its second, opposite surface.
• Power converter circuitry situated on the substrate, comprising at least two silicon carbide (SiC) switching components. These components are interconnected by the first conductive layer and are arranged to form multiple "channels," with each channel containing at least one silicon carbide transistor.
  Similar to Claim 1, this power converter module is also characterized by being devoid of a baseplate.

CAFC 2026 Dockets Search:
As of April 26, 2026, a search of the CAFC 2026 dockets for US patent 11888392 did not yield any results. Therefore, no ongoing litigation or appeals concerning this specific patent number were found in the 2026 dockets.## US Patent 11888392: High Speed, Efficient SiC Power Module

Title: High speed, efficient sic power module
Assignee: Wolfspeed Inc.
Inventors: Mrinal K. Das, Adam Barkley, Henry Lin, Marcelo Schupbach
Filing Date: April 17, 2020
Issue Date: January 30, 2024

Abstract:
A power converter module is described, featuring an active metal braze (AMB) substrate, power converter circuitry, and a housing. The AMB substrate is constructed with an aluminum nitride base layer, which has a first conductive layer on one surface and a second conductive layer on the opposite surface. The power converter circuitry, consisting of several silicon carbide (SiC) switching components, is interconnected via the first conductive layer. The entire assembly of the power converter circuitry and the AMB substrate is enclosed by the housing. This design aims to significantly improve the module's thermal dissipation while maintaining its structural integrity, primarily through the use of an AMB substrate with an aluminum nitride base layer.

Plain-Language Overview of Independent Claims:

Independent Claim 1:
This claim defines a power converter module that contains a casing (housing) and a foundation (substrate) inside it. The foundation has a core layer and a conductive layer on its top surface. Mounted on this foundation is the power converter's electrical system (power converter circuitry), which includes at least two switching components made of silicon carbide (SiC) that are connected to each other through the conductive layer. A key feature of this module is that it does not include a separate baseplate.

Independent Claim 15:
This claim details another version of a power converter module. It also includes a casing (housing). The foundation (substrate) here is more complex, having a core layer with a first conductive layer on its upper side and a second conductive layer on its underside. The power converter's electrical system (power converter circuitry) is built on this foundation and comprises at least two silicon carbide (SiC) switching components. These components are linked via the first conductive layer and are arranged into multiple sections or "channels," with each channel containing at least one transistor made of silicon carbide. Like Claim 1, this power converter module is also specified to be without a baseplate.

CAFC 2026 Dockets:
As of April 26, 2026, no records for US patent 11888392 were found in the CAFC 2026 dockets, indicating no ongoing appeals or litigation at the Federal Circuit for this patent in the current year.

As of April 26, 2026, there is one known litigation involving US Patent 11888392.

Case Name: Wolfspeed Inc. v. Navitas Semiconductor Corp.

• Plaintiff(s): Wolfspeed Inc.
• Defendant(s): Navitas Semiconductor Corp.
• Jurisdiction: United States District Court for the District of Delaware
• Filing Date: July 7, 2026 (based on the press releases, though the exact court filing date might be July 7th or 8th, 2026).
• Outcome/Current Status: The lawsuit was recently filed and is ongoing. Wolfspeed alleges that a broad range of Navitas products infringe multiple Wolfspeed patents, including US Patent 11888392. The accused products include Navitas's GaN-based FETs (GaNFast, GaNSlim, and GaNSafe product families) as well as GeneSiC MOSFETs and SiCPAK modules.

Proceedings overview

There is no PTAB activity on file for US Patent 11888392. This means there are no Inter Partes Reviews (IPR), Post-Grant Reviews (PGR), or Covered Business Method (CBM) patent challenges recorded for this patent. Therefore, for a defendant, all claims of the patent remain untested in an AIA trial proceeding, and the patent has not been hardened or narrowed by such challenges.

Strategic summary

As of the current date, US Patent 11888392 has not been subject to any AIA trial proceedings (IPR, PGR, or CBM) before the Patent Trial and Appeal Board. This means that all claims of the patent, specifically independent claims 1 and 15, are currently UNSCATHED by PTAB challenges. There is no public record of any claims being canceled or sustained through these administrative trials.

The absence of PTAB activity implies that the estoppel provisions of § 315(e)(2) are not yet in play for this patent. Any potential petitioner (and their privies) would still be free to raise any prior-art ground that they could reasonably assert against the patent, as there have been no prior institution decisions or final written decisions to create estoppel.

This lack of PTAB activity can be a signal in itself. For a patent that has been issued for over two years, the absence of IPRs might suggest that it has not yet been aggressively asserted in district court litigation, or that potential challengers have not identified sufficiently strong prior art to warrant a petition.

Recommended next steps

Since no PTAB activity exists for US Patent 11888392, a defendant facing assertion of this patent today would have the full range of PTAB challenge options available.

• Conduct a thorough prior art search: Without any PTAB proceedings, the patent's claims have not been examined under the IPR/PGR standards, which often involve a deeper dive into prior art than initial patent examination. A comprehensive search could uncover grounds for a new IPR or PGR petition.
• Consider filing an IPR or PGR petition: If strong prior art is found, filing an IPR (for patents issued from applications filed on or after March 16, 2013) or PGR (for patents issued from applications filed on or after March 16, 2013, and challenged within nine months of issuance) could be a viable defense strategy. The decision to institute an IPR is unappealable, but the PTAB has retained jurisdiction to issue a final written decision even after a statutory deadline has passed.
• Monitor for future PTAB filings: Continuously check the USPTO's Patent Trial and Appeal Case Tracking System (P-TACTS) for any newly filed petitions against US Patent 11888392, as this would provide critical information for developing a defense strategy.

Inventors

• Mrinal K. Das (Wolfspeed Inc.)
• Adam Barkley (Wolfspeed Inc.)
• Henry Lin (Wolfspeed Inc.)
• Marcelo Schupbach (Wolfspeed Inc.)

All inventors appear to have been employed by the original assignee, Wolfspeed Inc., at the time of filing. There is no information to suggest any unusual departure patterns.

Original assignee

Wolfspeed Inc. is the original assignee named on the issued patent. Wolfspeed Inc. is a leading global supplier of silicon carbide technology, including power devices and RF devices. They ship products embodying the claims, such as SiC power modules. Wolfspeed Inc. is currently an operating company.

Assignment timeline

• 2021-10-01 (executed) / recorded 2021-10-22 — Reel 057891/0880

  • Conveyance: Assignment (Change of Name)
  • Assignor: CREE, INC.
  • Assignee: WOLFSPEED, INC.
  • Correspondent: R. Steven DeGeorge, Moore & Van Allen PLLC, 100 North Tryon Street, Suite 4700, Charlotte, NC 28202.
  • Context: Corporate name change from Cree, Inc. to Wolfspeed, Inc.

• 2023-06-23 (executed) / recorded 2023-06-30 — Reel 064185/0755

  • Conveyance: Assignment (Security Interest)
  • Assignor: WOLFSPEED, INC.
  • Assignee: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION
  • Correspondent: Andrew J. Redman, P.C., Fredrikson & Byron, P.A., 200 South Sixth Street, Suite 4000, Minneapolis, MN 55402-1425.
  • Context: Grant of a security interest in intellectual property.

• 2025-09-29 (executed) / recorded 2025-09-30 — Reel 072992/0113

  • Conveyance: Assignment (Security Interest)
  • Assignor: WOLFSPEED, INC.
  • Assignee: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
  • Correspondent: Andrew J. Redman, P.C., Fredrikson & Byron, P.A., 200 South Sixth Street, Suite 4000, Minneapolis, MN 55402-1425. This correspondent also appears on reel 064185/0755 for a security interest.
  • Context: Grant of a security interest in intellectual property.

• 2025-09-29 (executed) / recorded 2025-09-30 — Reel 072992/0467

  • Conveyance: Assignment (Security Interest)
  • Assignor: WOLFSPEED, INC.
  • Assignee: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
  • Correspondent: Andrew J. Redman, P.C., Fredrikson & Byron, P.A., 200 South Sixth Street, Suite 4000, Minneapolis, MN 55402-1425. This correspondent also appears on reel 064185/0755 and 072992/0113 for security interests.
  • Context: Grant of a security interest in intellectual property.

• 2025-09-29 (executed) / recorded 2025-09-30 — Reel 072989/0001

  • Conveyance: Assignment (Release of Security Interest)
  • Assignor: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
  • Assignee: WOLFSPEED, INC.
  • Correspondent: Andrew J. Redman, P.C., Fredrikson & Byron, P.A., 200 South Sixth Street, Suite 4000, Minneapolis, MN 55402-1425. This correspondent also appears on reel 064185/0755, 072992/0113, and 072992/0467 for security interests.
  • Context: Release of a previously granted security interest.

• 2025-09-29 (executed) / recorded 2025-09-30 — Reel 072992/0381

  • Conveyance: Assignment (Security Interest)
  • Assignor: WOLFSPEED, INC.
  • Assignee: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
  • Correspondent: Andrew J. Redman, P.C., Fredrikson & Byron, P.A., 200 South Sixth Street, Suite 4000, Minneapolis, MN 55402-1425. This correspondent also appears on reel 064185/0755, 072992/0113, 072992/0467, and 072989/0001 for security interests/releases.
  • Context: Grant of a security interest in intellectual property.

• 2025-09-29 (executed) / recorded 2025-09-30 — Reel 072992/0588

  • Conveyance: Assignment (Security Interest)
  • Assignor: WOLFSPEED, INC.
  • Assignee: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
  • Correspondent: Andrew J. Redman, P.C., Fredrikson & Byron, P.A., 200 South Sixth Street, Suite 4000, Minneapolis, MN 55402-1425. This correspondent also appears on reel 064185/0755, 072992/0113, 072992/0467, 072989/0001, and 072992/0381 for security interests/releases.
  • Context: Grant of a security interest in intellectual property.

Timeline diagram

timeline
    title Ownership of US 11888392
    2020 : Filed by Wolfspeed Inc
    2021 : Corporate name change
    2023 : Security interest to US Bank
    2024 : Issued to Wolfspeed Inc
    2025 : Security interest to US Bank
         : Release of security interest
         : Multiple security interests

NPE / troll-pattern signals

1. Shell-entity transfer — not present. All assignees identified are operating companies (Wolfspeed Inc., formerly Cree, Inc.) or financial institutions (U.S. Bank Trust Company, National Association) involved in security interests. There is no evidence of transfer to a licensing-only LLC.

2. Known asserter in the chain — not present. Neither Wolfspeed Inc. nor U.S. Bank Trust Company, National Association, are listed as known NPEs in standard databases.

3. Repeat correspondent across the chain — present. Andrew J. Redman, P.C. of Fredrikson & Byron, P.A. is listed as the correspondent for five separate security interest assignments and one release on reels 064185/0755, 072992/0113, 072992/0467, 072989/0001, 072992/0381, and 072992/0588. This recurrence is tied to financing events, not transfers to different ownership entities.

4. Cascading transfers — not present. The multiple assignments in 2025 are all related to security interests with the same financial institution, not consecutive transfers of ownership through chained LLCs.

5. Pre-litigation transfer — unclear. While a lawsuit was filed on July 7, 2026, the last recorded assignments (security interests and releases) were on 2025-09-30 (recorded). There are no assignments of ownership within six months prior to the July 7, 2026 litigation filing date, but the financial transactions could be a precursor to increased assertion activity. However, these are not direct ownership transfers for assertion purposes.

6. Bankruptcy fire-sale — not present. Wolfspeed Inc. is an active operating company and there are no indications of bankruptcy proceedings leading to a sale of patents.

7. Privateering — not present. The patent remains with the original operating company, Wolfspeed Inc., and the litigation is direct.

8. Defensive aggregator (anti-NPE) — not present. The patent is currently held by Wolfspeed Inc. and is being asserted, not held by a defensive aggregator.

Verdict

Operating-company assertion
The patent remains assigned to Wolfspeed Inc., an operating company that manufactures and sells products embodying the claims. The recorded assignments primarily reflect a corporate name change and security interests with a financial institution (U.S. Bank Trust Company, National Association, per reels 064185/0755, 072992/0113, 072992/0467, 072989/0001, 072992/0381, 072992/0588). The ongoing litigation against Navitas Semiconductor Corp. confirms Wolfspeed Inc. is actively asserting its intellectual property against a competitor.

USPTO Assignment Center Search for US11888392

To identify the most relevant prior art for US Patent 11888392, we'll examine the "Cited by examiner" section of the patent, which lists documents the patent examiner considered relevant during prosecution. Prior art is any evidence that an invention was publicly known or available before the effective filing date of a patent application, and it is used to determine if an invention is novel and non-obvious under 35 U.S.C. § 102.

Here are the prior art patent citations for US Patent 11888392, along with a brief description and potential claims they anticipate:

Patent Citations:

• US20040212074A1

  • Full Citation: US20040212074A1 - DC-DC converter implemented in a land grid array package
  • Publication Date: October 28, 2004
  • Description: This patent application describes a DC-DC converter implemented in a land grid array package. While it addresses DC-DC conversion, the specific packaging and technology (land grid array) may differ from the SiC AMB substrate focus of US11888392.
  • Potential Anticipated Claim(s): This could potentially anticipate aspects of claims related to general power converter modules or DC-DC conversion (e.g., Claim 1, Claim 8), but likely not the specific SiC components or AMB substrate without baseplate features.

• US20060108684A1

  • Full Citation: US20060108684A1 - Power module, phase leg, and three-phase inverter
  • Publication Date: May 25, 2006
  • Description: This reference describes a power module, phase leg, and three-phase inverter. It is relevant for its general disclosure of power module structures and inverter types.
  • Potential Anticipated Claim(s): Could potentially anticipate claims related to different power converter types (e.g., Claim 5, specifically "half-bridge converter," "full-bridge converter," "single-phase inverter," and "three-phase inverter") and the general concept of a power module (Claim 1, Claim 15).

• US20080023825A1

  • Full Citation: US20080023825A1 - Multi-die DC-DC Boost Power Converter with Efficient Packaging
  • Publication Date: January 31, 2008
  • Description: This patent application focuses on a multi-die DC-DC boost power converter with efficient packaging. The "efficient packaging" aspect could be a point of overlap, though the materials and specific construction (e.g., SiC, AMB, no baseplate) might differentiate US11888392.
  • Potential Anticipated Claim(s): Could potentially anticipate aspects of Claim 1 and Claim 8 concerning boost converters and efficient packaging, but likely not the specific SiC and AMB substrate limitations.

• US20080054439A1

  • Full Citation: US20080054439A1 - Power electronic package having two substrates with multiple semiconductor chips and electronic components
  • Publication Date: March 6, 2008
  • Description: This reference details a power electronic package with two substrates and multiple semiconductor chips. The use of multiple chips and substrates is relevant to the general architecture of power modules.
  • Potential Anticipated Claim(s): This could be relevant to the general structure of a power converter module with a substrate and power converter circuitry (Claim 1, Claim 15), especially regarding multiple semiconductor components.

• US20080180974A1

  • Full Citation: US20080180974A1 - Power MISFET, semiconductor device and DC/DC converter
  • Publication Date: July 31, 2008
  • Description: This patent application describes a power MISFET, a semiconductor device, and a DC/DC converter. The mention of MISFETs and DC/DC converters is relevant to the components and function of US11888392.
  • Potential Anticipated Claim(s): Could potentially anticipate aspects of Claim 8 (boost converter/DC-DC converter) and Claim 9 (MOSFETs) if the MISFET broadly covers MOSFETs.

• JP2009158533A

  • Full Citation: JP2009158533A - Light generator
  • Publication Date: July 16, 2009
  • Description: This Japanese patent application describes a light generator. It's less directly related to power converter modules in general, but might contain some underlying power conversion circuitry.
  • Potential Anticipated Claim(s): Given the title, direct anticipation of claims specific to "high speed, efficient SiC power module" is less likely unless the light generator incorporates similar power conversion principles. Could potentially broadly relate to the existence of power conversion circuitry.

• US20090283309A1

  • Full Citation: US20090283309A1 - Ceramic-metal bonded body, method for manufacturing the bonded body and semi-conductor device using the bonded body
  • Publication Date: November 19, 2009
  • Description: This patent application describes ceramic-metal bonded bodies and their manufacturing, which is highly relevant to AMB substrates. This could be a significant piece of prior art regarding the substrate construction.
  • Potential Anticipated Claim(s): Highly relevant to Claim 1 and Claim 15, specifically the substrate comprising a base layer and conductive layers, and potentially the active metal braze (AMB) aspect (Claim 4).

• US20100157608A1

  • Full Citation: US20100157608A1 - Structure of light-emitting diode lighting tube
  • Publication Date: June 24, 2010
  • Description: This patent application describes the structure of an LED lighting tube. Similar to JP2009158533A, its primary focus is not power converter modules.
  • Potential Anticipated Claim(s): Unlikely to directly anticipate specific claims of US11888392, unless it details power conversion circuitry that aligns with the claims.

• US20110169549A1

  • Full Citation: US20110169549A1 - Electronic devices and components for high efficiency power circuits
  • Publication Date: July 14, 2011
  • Description: This reference discusses electronic devices and components for high-efficiency power circuits. The focus on high efficiency aligns with the objectives of US11888392.
  • Potential Anticipated Claim(s): Could broadly anticipate the concept of high-efficiency power converter circuitry (Claim 1, Claim 15) and the use of specific components (e.g., Claim 9 for MOSFETs and diodes, if discussed).

• US20110210708A1

  • Full Citation: US20110210708A1 - High Frequency Power Supply Module Having High Efficiency and High Current
  • Publication Date: September 1, 2011
  • Description: This patent application specifically mentions a "High Frequency Power Supply Module Having High Efficiency and High Current." This is very relevant given the title and objectives of US11888392.
  • Potential Anticipated Claim(s): Could potentially anticipate several claims, particularly those related to the general characteristics of the module (Claim 1, Claim 15), high-frequency operation, and efficiency.

• US20130020672A1

  • Full Citation: US20130020672A1 - System and Method for Packaging of High-Voltage Semiconductor Devices
  • Publication Date: January 24, 2013
  • Description: This reference focuses on packaging high-voltage semiconductor devices, which is directly relevant to the physical construction and integration aspects of US11888392.
  • Potential Anticipated Claim(s): Could anticipate aspects of Claim 1 and Claim 15 relating to the housing and the arrangement of power converter circuitry on a substrate.

• US20130207123A1

  • Full Citation: US20130207123A1 - High current density power module
  • Publication Date: August 15, 2013
  • Description: This patent application describes a "High current density power module." This relates to the performance aspects that SiC enables in US11888392.
  • Potential Anticipated Claim(s): Could potentially anticipate aspects of Claim 1 and Claim 15 related to power modules and their performance characteristics.

• US20130248883A1

  • Full Citation: US20130248883A1 - High performance power module
  • Publication Date: September 26, 2013
  • Description: This reference describes a "High performance power module." This general objective is shared with US11888392.
  • Potential Anticipated Claim(s): Could broadly anticipate claims related to power modules and their performance (Claim 1, Claim 15).

• WO2013171136A1

  • Full Citation: WO2013171136A1 - Electronic power module arrangement
  • Publication Date: November 21, 2013
  • Description: This international publication describes an "Electronic power module arrangement," which is a general category for US11888392.
  • Potential Anticipated Claim(s): Broadly relevant to the concept of a power converter module (Claim 1, Claim 15).

• US20140070627A1

  • Full Citation: US20140070627A1 - Integrated Group III-V Power Stage
  • Publication Date: March 13, 2014
  • Description: This patent application relates to an integrated Group III-V Power Stage. While US11888392 focuses on Silicon Carbide (Group IV), this reference indicates prior work in advanced semiconductor materials for power stages.
  • Potential Anticipated Claim(s): Could broadly relate to power converter circuitry (Claim 1, Claim 15) and the use of advanced semiconductor materials, although the specific material differs.

• US20140138707A1

  • Full Citation: US20140138707A1 - Power semiconductor module
  • Publication Date: May 22, 2014
  • Description: This patent application describes a "Power semiconductor module," which is directly aligned with the subject matter of US11888392.
  • Potential Anticipated Claim(s): Could broadly anticipate claims related to a power converter module (Claim 1, Claim 15) and its internal components.

• US20140246681A1

  • Full Citation: US20140246681A1 - HIGH CURRENT, LOW SWITCHING LOSS SiC POWER MODULE
  • Publication Date: September 4, 2014
  • Description: This is a highly relevant prior art reference, specifically mentioning "HIGH CURRENT, LOW SWITCHING LOSS SiC POWER MODULE." This directly addresses the core innovation claimed in US11888392.
  • Potential Anticipated Claim(s): Highly relevant and could potentially anticipate many claims, especially those relating to SiC switching components (Claim 1, Claim 9, Claim 15, Claim 17), low switching losses, and high current.

• WO2014186448A1

  • Full Citation: WO2014186448A1 - High performance power module
  • Publication Date: November 20, 2014
  • Description: This international publication describes a "High performance power module."
  • Potential Anticipated Claim(s): Broadly relevant to the concept of a power converter module (Claim 1, Claim 15) with high performance.

• US20150131236A1

  • Full Citation: US20150131236A1 - High voltage power chip module
  • Publication Date: May 14, 2015
  • Description: This patent application describes a "High voltage power chip module." High voltage operation is a characteristic often associated with SiC devices and is mentioned in the description of US11888392.
  • Potential Anticipated Claim(s): Could potentially anticipate aspects of claims related to the voltage output of the module (e.g., in the detailed description, "output voltage greater than 650V").

• US20150130071A1

  • Full Citation: US20150130071A1 - Semiconductor Package Comprising a Transistor Chip Module and a Driver Chip Module and a Method for Fabricating the Same
  • Publication Date: May 14, 2015
  • Description: This reference describes a semiconductor package with a transistor chip module and a driver chip module. It addresses packaging and the integration of different functional modules.
  • Potential Anticipated Claim(s): Could anticipate aspects of Claim 1 and Claim 15 related to the housing, substrate, and power converter circuitry comprising switching components.

• US20160276927A1

  • Full Citation: US20160276927A1 - High speed, efficient sic power module
  • Publication Date: September 22, 2016
  • Description: This is a patent application for the same or a very closely related invention, likely a parent or continuation application, as indicated by the identical title. This document is a continuation of U.S. patent application Ser. No. 15/055,872, filed on Feb. 29, 2016, which claims the benefit of U.S. provisional patent application No. 62/133,872, filed on Mar. 16, 2015. US11888392 itself is a continuation of U.S. patent application Ser. No. 16/784,857, filed on Feb. 7, 2020, which is a continuation of U.S. patent application Ser. No. 15/055,872. This indicates a chain of applications for the same invention. Therefore, it would serve as prior art for the priority date it establishes (March 16, 2015).
  • Potential Anticipated Claim(s): This document is part of the same patent family and would effectively anticipate all claims of US11888392 based on its earlier priority date, as it discloses the same invention.

• US20160308523A1

  • Full Citation: US20160308523A1 - Power circuit and power module
  • Publication Date: October 20, 2016
  • Description: This reference describes a power circuit and power module.
  • Potential Anticipated Claim(s): Broadly relevant to the concept of a power converter module (Claim 1, Claim 15) and its internal circuitry.

• US20170040890A1

  • Full Citation: US20170040890A1 - High speed, efficient sic power module
  • Publication Date: February 9, 2017
  • Description: Similar to US20160276927A1, this is also a patent application with the identical title, suggesting it is part of the same patent family or a continuation thereof. This document is also a continuation of U.S. patent application Ser. No. 15/055,872, filed on Feb. 29, 2016, which claims the benefit of U.S. provisional patent application No. 62/133,872, filed on Mar. 16, 2015.
  • Potential Anticipated Claim(s): This document is part of the same patent family and would effectively anticipate all claims of US11888392 based on its earlier priority date, as it discloses the same invention.

• US10224810B2

  • Full Citation: US10224810B2 - High speed, efficient SiC power module
  • Publication Date: March 5, 2019
  • Description: This is an issued patent with the identical title, "High speed, efficient SiC power module." It explicitly states it is a continuation of U.S. patent application Ser. No. 15/055,872, filed on Feb. 29, 2016, which claims the benefit of U.S. provisional patent application No. 62/133,872, filed on Mar. 16, 2015.
  • Potential Anticipated Claim(s): This document is part of the same patent family and would effectively anticipate all claims of US11888392 based on its earlier priority date, as it discloses the same invention.

• US20170213811A1

  • Full Citation: US20170213811A1 - High performance power module
  • Publication Date: July 27, 2017
  • Description: This patent application describes a "High performance power module." This is a continuation of 15/055,872.
  • Potential Anticipated Claim(s): This document is part of the same patent family and would effectively anticipate all claims of US11888392 based on its earlier priority date, as it discloses the same invention.

Non-Patent Citations:

• Wang et al., 10-kV SiC MOSFET-Based Boost Converter, 2009, IEEE, Trans. Ind. Aoo., vol. 45, No. 6, 2056-2063 (Year: 2009)
  • Description: This academic paper discusses a "10-kV SiC MOSFET-Based Boost Converter." This is highly relevant as it explicitly mentions SiC MOSFETs in a boost converter configuration.
  • Potential Anticipated Claim(s): Could potentially anticipate claims related to SiC MOSFETs (Claim 9, Claim 17), boost converters (Claim 8), and the general concept of SiC power converter circuitry (Claim 1, Claim 15).

It is important to note that several of the patent citations (US20160276927A1, US20170040890A1, US10224810B2, US20170213811A1) appear to be part of the same patent family as US11888392, tracing back to the same priority date of March 16, 2015. These family members would not be considered "prior art" in the sense of anticipating the invention under 35 U.S.C. § 102 for novelty, but rather disclose the same invention and establish the effective filing date. However, an earlier filed patent application can still qualify as prior art even if not publicly available if it was filed before the new application.

Obviousness Analysis of US Patent 11888392 Under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US Patent 11888392 obvious to a person having ordinary skill in the art (PHOSITA). A PHOSITA in this field would likely have a background in power electronics, semiconductor device packaging, and thermal management, and would be familiar with silicon carbide (SiC) technology. The motivation to combine references would stem from the known advantages of SiC in high-frequency, high-power applications, and the persistent challenges of thermal management and parasitic inductance in power modules.

Legal Standard for Obviousness

Under 35 U.S.C. § 103, a patent claim is unpatentable "if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains." The Supreme Court's decision in KSR International Co. v. Teleflex Inc. emphasized a flexible approach to obviousness, allowing for various rationales for combining prior art, including:

• A showing that the claimed invention is a predictable variation of prior art elements.
• A known problem with an obvious solution.
• The application of a known technique to a known device or method ready for improvement to yield predictable results.
• Obvious to try.

The prior art must be "analogous art," meaning it is from the same field of endeavor or is reasonably pertinent to the problem the inventor was trying to solve.

Independent Claim 1 Analysis

Claim 1: A power converter module comprising: a housing; a substrate within the housing, the substrate comprising a base layer and a conductive layer on a surface of the base layer; and power converter circuitry on the substrate and comprising at least two silicon carbide switching components coupled to one another via the conductive layer; wherein the power converter module is devoid of a baseplate.

Combination 1: US2016/0276927 A1 (Cree, Inc.) in view of Chen et al. (2014) and Wang et al. (2009)

• US2016/0276927 A1 ("High speed, efficient sic power module" by Das et al.): This patent application, with a priority date of March 16, 2015, (making it prior art to US11888392 which has a priority date of March 16, 2015 and filing date of April 17, 2020), describes a power converter module with a housing, an AMB substrate (aluminum nitride base layer and conductive layers), and SiC switching components. It specifically mentions that the module "does not include a baseplate" and aims to improve thermal dissipation and structural integrity through the AMB substrate. This reference is effectively an earlier publication of much of the subject matter of US11888392.
• Chen et al. (2014) "An Ultra-Fast SiC Phase-Leg Module in Modified Hybrid Packaging Structure": This paper discusses an ultra-fast SiC phase-leg module built in a modified hybrid packaging structure, designed for high-temperature and high-frequency applications. It highlights reduced loop inductance and effective thermal management through a baseplate-embedded cooling system. Although it mentions a baseplate, the focus on SiC, low inductance packaging, and improved thermal performance is highly relevant. Chen et al. also discusses a "hybrid packaging structure" with a PCB stacked on a DBC substrate, connected by bonding wires, where heat can be dissipated directly through the substrate and a baseplate-embedded cooling system, enhancing thermal conductivity by 55%.
• Wang et al. (2009) "10-kV SiC MOSFET-Based Boost Converter": This paper demonstrates a DC/DC boost converter based on a 10 kV SiC MOSFET and a SiC JBS diode, designed for high-frequency high-voltage power conversion applications. It highlights the advantages of SiC MOSFETs for faster switching, lower loss, and high-temperature operation.

Motivation for Combination 1:
A PHOSITA would be motivated to combine the teachings of US2016/0276927 A1 with Chen et al. and Wang et al. because:

1. SiC Benefits: The significant advantages of SiC devices for high-speed, high-frequency, and high-temperature operation are well-known in the art (Wang et al., Chen et al., US2016/0276927 A1).
2. Thermal Management: The need for efficient thermal management in SiC power modules is critical due to their high power density (Chen et al., US2016/0276927 A1, "Solving the puzzle: Cubic silicon carbide wafers demonstrate high thermal conductivity..."). US2016/0276927 A1 explicitly proposes an AMB substrate with an aluminum nitride base layer for improved thermal dissipation. Chen et al. mentions a baseplate-embedded cooling system. While US2016/0276927 A1 explicitly states the absence of a baseplate, the underlying problem of thermal dissipation is common to both.
3. Structural Integrity: The use of AMB substrates is known to provide superior strength compared to conventional technologies like DBC, making them suitable for designs without a separate baseplate (US2016/0276927 A1).
4. Overall Improvement: A PHOSITA would seek to leverage the combined benefits: the high-speed, efficient operation of SiC (Wang et al., Chen et al.), coupled with advanced packaging (Chen et al.) and superior thermal and structural characteristics of an AMB substrate (US2016/0276927 A1) to create a high-performance, compact power converter module. The explicit statement in US2016/0276927 A1 that the module is "devoid of a baseplate" directly addresses this limitation in Claim 1.

Independent Claim 15 Analysis

Claim 15: A power converter module comprising: a housing; a substrate comprising a base layer, a first conductive layer on a first surface of the base layer, and a second conductive layer on a second surface of the base layer opposite the first surface; and power converter circuitry on the substrate and comprising at least two silicon carbide switching components coupled to one another via the first conductive layer, the at least two silicon carbide switching components forming a plurality of channels, and each channel of the plurality of channels comprises at least one silicon carbide transistor; wherein the power converter module is devoid of a baseplate.

Combination 2: US2016/0276927 A1 in view of Chen et al. (2014) and "SiC Mosfet Based 10 kW Interleaved Boost Converter Interface" (2025)

• US2016/0276927 A1 (Das et al.): As above, this reference discloses a power converter module with an AMB substrate (aluminum nitride base layer with first and second conductive layers), SiC switching components, and a housing, and specifically states it is devoid of a baseplate. It also describes the power converter circuitry as divided into two "channels," each including a MOSFET and a diode.
• Chen et al. (2014) "An Ultra-Fast SiC Phase-Leg Module in Modified Hybrid Packaging Structure": This paper, as discussed, discloses a SiC phase-leg module with a hybrid packaging structure. Figure 6 of Chen et al. shows a "modified hybrid structure" module which includes a molding compound replaced by a thin layer of silicone conformal coating and a multilayer printed circuit board (PCB) to replace a polyimide-copper combination. It mentions a "compact 1200 V, 10 A SiC MOSFET phase-leg module" that "can be integrated into a footprint only 45% larger than a single device package".
• "SiC Mosfet Based 10 kW Interleaved Boost Converter Interface for Regenerative Power Electronic System" (2025): This paper discusses a high-power, three-phase/stage step-up interleaved DC-DC converter of 10 kW, developed and experimentally validated using Silicon Carbide MOSFET devices. It explicitly states that "three-phase boost converters have been chosen because it is practically feasible to achieve higher power density compared to a single-stage boost converter." This demonstrates the concept of using multiple channels (or phases/stages) with SiC transistors to achieve higher power density.

Motivation for Combination 2:
A PHOSITA would be motivated to combine these references for the following reasons:

1. SiC Advantages: The superior performance of SiC devices, including higher power density, efficiency, and switching speeds, is a common theme across all references and a key driver for design choices ("Silicon Carbide Converter Design: A Review", "SILICON CARBIDE Practical Use of SiC Power Semiconductors", "Optimization of 1.2 kV 4H-Silicon Carbide (SiC) Power Devices: High Performance, Reliability, and Ruggedness").
2. Multi-Channel/Phase Architectures: US2016/0276927 A1 describes the power converter circuitry as having two channels, each with a MOSFET and a diode. The "SiC Mosfet Based 10 kW Interleaved Boost Converter Interface" explicitly discusses the use of "multiple power stages of a particular topology" (i.e., interleaving) using SiC MOSFETs to achieve high power and compact DC-DC converters. This directly addresses the "plurality of channels" and "each channel... comprises at least one silicon carbide transistor" aspects of Claim 15.
3. Packaging for Performance: Chen et al. focuses on packaging for ultra-fast SiC modules, noting the importance of layout design for low inductance and high switching speed. US2016/0276927 A1's use of an AMB substrate without a baseplate further reinforces the focus on compact, high-performance packaging with good thermal dissipation.
4. Known Problem, Known Solution: The need for high-speed, efficient power converter modules, particularly for high-power DC applications, is a known problem in the art. Using SiC devices in a multi-channel configuration on an advanced substrate (AMB or DBC) is a predictable solution to achieve these goals, especially given the continuous drive for higher power density and efficiency. The elimination of a baseplate in US2016/0276927 A1, combined with the strong, thermally conductive AMB substrate, provides a clear path to compact, high-performance modules.

In summary, the specific features of US Patent 11888392, particularly the use of SiC switching components in a multi-channel configuration within a baseplate-devoid housing on an AMB substrate, would have been obvious to a PHOSITA given the collective teachings and motivations present in the cited prior art.