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Researchers Submit Patent Application, "Heat Radiation Structure of Electric Device and Method for Manufacturing the Same", for Approval

August 27, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors YAMANAKA, Takahiro (Kariya-city, JP); HARA, Yoshimichi (Kuwana-city, JP); YAMAMOTO, Toshihisa (Anjo-city, JP); KAMEYAMA, Kouji (Anjo-city, JP); KOBAYASHI, Yuuji (Nukata-gun, JP), filed on January 29, 2014, was made available online on August 14, 2014.

The patent's assignee is Denso Corporation.

News editors obtained the following quote from the background information supplied by the inventors: "Conventionally, a technique relating to a multi-layer substrate, which has excellent heat radiation property of a semiconductor element and has a low manufacturing cost, is disclosed in, for example, JP-A-2004-158545. The multi-layer substrate includes a heat radiation plate, which is disposed on both sides in an upper-lower direction and is insulated from the semiconductor element.

"However, in a heat radiation structure of the semiconductor element such as a MOS-FET (i.e., metal oxide semiconductor field effect transistor), which provides a motor driving circuit, a surface mounting element such as a SMD (i.e., surface mount device) and a bare chip including a package is mounted on a surface of a substrate, and a back surface of the substrate contacts the heat radiation body so as to radiate heat. In this structure, no element is mounted on the back surface. Further, since the heat is radiated via the substrate, the heat radiation efficiency is not good.

"Alternatively, a structure is proposed such that a surface mounted element having a heat radiation surface opposite to a substrate mounting surface is used, and the heat radiation surface of the surface mounted element contacts a heat radiation plate via a heat conducting member. When multiple surface mounted elements are mounted on the substrate, and a heat radiation body is attached, if the thickness (i.e., a height) of each surface mounted element is varied, the thickness of the heat conducting member is also varied. Further, since the heat radiation body is an electric conductor in general, it is necessary to secure the insulating property between the heat radiation body and the surface mounted element with the heat conducting member. Thus, it is necessary to secure the insulating property between the surface mounted element having the smallest thickness and the heat radiation body with the heat conducting member and to design thermally in view of the surface mounted element with the heat conducting member having the largest thickness. Accordingly, it is necessary to use the heat conducting member having high performance, compared with a case where a single item is attached to the heat radiation body.

"The above difficulties also arise in the multi-layer substrate described in JP-A-2004-158545."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "It is an object of the present disclosure to provide a heat radiation structure of an electric device having high heat radiation performance of the electric element. Further, even when the heat radiation structure includes multiple layers having different thicknesses and multiple electric elements having different heights, a gap in the multi-layer substrate is easily controlled.

"According to a first aspect of the present disclosure, a heat radiation structure for an electric device includes: at least one multi-layer substrate including a plurality of base parts made of insulation material and a conductor pattern, which are stacked in a multi-layer structure so that the conductor pattern is electrically coupled with an interlayer connection portion in the base parts; the electric device having at least one of a first electric element built in the at least one multi-layer substrate and a second electric element, which is not built in the multi-layer substrate; and a low heat resistance element opposed to the electric device. The low heat resistance element has a heat resistance lower than the insulation material.

"In the above structure, the low heat resistance element is arranged to face multiple electric elements even when the electric elements are accommodated in the multi-layer substrate. Even when the initial height or the initial thickness of the multi-layer substrate and the electric element are different from each other, the height or the thickness are equalized by the heating and pressing process. Thus, the clearance in the structure is easily controller. Further, since the low heat resistance element has the low heat resistance, the heat generated at the electric element is transmitted. Thus, the heat radiation performance of the electric element is improved.

"According to a second aspect of the present disclosure, a method for manufacturing a heat radiation structure for an electric device includes: forming a conductor pattern on one of or both of surfaces of each base part, which is made of insulation material; forming a via hole at a predetermined position of each base part; filling the via hole with an interlayer connection member; accommodating a first electric element in an accommodation portion of one of the base parts, the first electric element being included in the electric device; stacking a plurality of base parts so as to form a stacked body; heating and pressing the stacked body with a press die so that the base parts are bonded to each other so as to form a multi-layer substrate; and heating and press-bonding a low heat resistance element on one surface of at least one multi-layer substrate via a heat conducting member, or arranging and heating the low heat resistance element directly on one surface of at least one multi-layer substrate.

"In the above method, since the heating and press-bonding of the low heat resistance element or the arranging and heating of the low heat resistance element is performed, the low heat resistance element is arranged to face multiple electric elements including the electric element in the multi-layer substrate. Even when the initial height or the initial thickness of the multi-layer substrate and the electric element are different from each other, the height or the thickness are equalized by the heating and pressing process. Thus, the clearance in the structure is easily controller. Further, since the low heat resistance element has the low heat resistance, the heat generated at the electric element is transmitted. Thus, the heat radiation performance of the electric element is improved.

"According to a third aspect of the present disclosure, a method for manufacturing a heat radiation structure for an electric device includes: arranging a plurality of electric elements on a circuit board along a stacking direction of the electric elements and the circuit board; and arranging, heating and bonding a low heat resistance element on the plurality of electric elements via a heat conducting member opposite to the circuit board.

"In the above method, even when the initial height of multiple electric elements arranged along the direction different from the stacking direction are different from each other, the height are equalized by the heating and pressing process. Thus, the clearance in the structure is easily controller. Further, since the low heat resistance element has the low heat resistance, the heat generated at the electric element is transmitted. Thus, the heat radiation performance of the electric element is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

"The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

"FIG. 1 is a diagram showing a cross sectional view of a heat radiation structure of an electric element according to a first embodiment;

"FIG. 2 is a diagram showing a control system for controlling a electric rotating machine;

"FIG. 3 is a diagram showing an example of a base part forming process;

"FIG. 4 is a diagram showing an example of a stacking process;

"FIG. 5 is a diagram showing an example of a hot pressing process;

"FIG. 6 is a diagram showing an example of height difference of multiple multi-layer substrates;

"FIG. 7 is a diagram showing an example of a forming process or an arranging and heating process;

"FIG. 8 is a diagram showing a cross sectional view of the second heat radiation structure of the electric element;

"FIG. 9 is a diagram showing a cross sectional view of the heat radiation structure of the electric element;

"FIG. 10 is a diagram showing a cross sectional view of a heat radiation structure of an electric element according to a second embodiment;

"FIG. 11 is a diagram showing an example of a height difference of an electric element and a multi-layer substrate;

"FIG. 12 is a diagram showing an example of a forming process or an arranging and heating process;

"FIG. 13 is a diagram showing a cross sectional view of the heat radiation structure of the electric element;

"FIG. 14 is a diagram showing a cross sectional view of a heat radiation structure of an electric element according to a third embodiment;

"FIG. 15 is a diagram showing an example of a height difference of multiple electric elements;

"FIG. 16 is a diagram showing an example of an arranging and heating process;

"FIG. 17 is a diagram showing a cross sectional view of a heat radiation structure of an electric element according to other embodiments;

"FIG. 18 is a diagram showing a cross sectional view of a heat radiation structure of an electric element according to the other embodiments; and

"FIG. 19 is a diagram showing a cross sectional view of a heat radiation structure of an electric element according to the other embodiments."

For additional information on this patent application, see: YAMANAKA, Takahiro; HARA, Yoshimichi; YAMAMOTO, Toshihisa; KAMEYAMA, Kouji; KOBAYASHI, Yuuji. Heat Radiation Structure of Electric Device and Method for Manufacturing the Same. Filed January 29, 2014 and posted August 14, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4757&p=96&f=G&l=50&d=PG01&S1=20140807.PD.&OS=PD/20140807&RS=PD/20140807

Keywords for this news article include: Electronics, Circuit Board, Semiconductor, Denso Corporation.

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Source: Electronics Newsweekly


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