News Column

Patent Issued for Power Semiconductor Module and Its Attachment Structure

June 25, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Asada, Shinsuke (Chiyoda-ku, JP); Watanabe, Yuetsu (Chiyoda-ku, JP); Asao, Yoshihito (Chiyoda-ku, JP); Nagao, Kenjiro (Chiyoda-ku, JP), filed on August 5, 2011, was published online on June 10, 2014.

The assignee for this patent, patent number 8749977, is Mitsubishi Electric Corporation (Tokyo, JP).

Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to power semiconductor modules and, more particularly, relates to a power semiconductor module and its attachment structure, each of which constitutes one used by being incorporated in a vehicular rotary electric machine, for example, a relay circuit and an inverter circuit for use in a rotary electric machine for a vehicular electric power steering system.

"As a conventional power semiconductor module, for example, one disclosed in Japanese Patent Gazette No. 4540884 (Patent Document 1) may be used. In such a module, a plurality of semiconductor devices are directly arranged on a conductive heat dissipation substrate and these are integrally formed in a resin package by transfer mold molding together with a plurality of external connection electrodes electrically connected to the semiconductor devices.

"A resin package on the surface side opposite to the surface of the heat dissipation substrate on which the plurality of the semiconductor devices are arranged is thin; the heat emitted from the semiconductor devices passes through the heat dissipation substrate and then further passes through the thin resin package to be dissipated to a heat sink attached outside the power semiconductor module. Incidentally, the power semiconductor module and the heat sink are bonded via heat dissipating adhesive or the like."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "The present invention has been made to solve the foregoing problem and is to provide a power semiconductor module and its attachment structure, each of which is excellent in heat dissipation properties even in a small size, and short circuit failure is prevented.

"Means for Solving the Problems

"According to the present invention, there is provided a power semiconductor module including: a first metal substrate on which a power semiconductor device is mounted; a second metal substrate on which a power semiconductor device is not mounted; and an electrically insulating resin package which seals the first metal substrate and the second metal substrate. In the power semiconductor module, the back surface of the first metal substrate on the side opposite to the mounting surface of the power semiconductor device is made to expose outside the resin package to form a heat dissipation surface.

"Furthermore, there is provided an attachment structure of a power semiconductor module in which the heat dissipation surface of the power semiconductor module is attached to a base surface formed on a heat sink via an electrically insulating bonding member.

"Advantageous Effect of the Invention

"According to a power semiconductor module of the present invention, among a plurality of metal substrates, at least a metal substrate on which a power semiconductor device is mounted has the back surface on the side opposite to the mounting surface of the power semiconductor device, the back surface being exposed to the heat dissipation surface of a resin package, and the majority of other metal substrates is embedded in the resin package; and therefore, high heat dissipation properties can be obtained. Furthermore, as a result, an increase of a heat dissipation area for improving heat dissipation properties is suppressed; and therefore, the power semiconductor module can be reduced in size. Furthermore, metal substrates other than that serve as internal wirings or the like and a need of heat dissipation is low and therefore protected by being embedded in the insulating resin package. Accordingly, a risk that causes short circuit failure can be reduced, the short circuit failure being caused by a conductive foreign object attached across between the metal substrates during a process in which the power semiconductor module is assembled to a heat sink. If all the metal substrates are exposed to the heat dissipation surface, the distance between the metal substrates needs to be enlarged in order to reduce the aforementioned risk; however, according to the present invention, there is no need for it and therefore the power semiconductor module can be reduced in size.

"The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings."

For more information, see this patent: Asada, Shinsuke; Watanabe, Yuetsu; Asao, Yoshihito; Nagao, Kenjiro. Power Semiconductor Module and Its Attachment Structure. U.S. Patent Number 8749977, filed August 5, 2011, and published online on June 10, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8749977.PN.&OS=PN/8749977RS=PN/8749977

Keywords for this news article include: Electronics, Semiconductor, Mitsubishi Electric Corporation.

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Source: Electronics Newsweekly


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