JP2016139691A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device having improved reliability in a power semiconductor device using a semiconductor element which operates at high temperature by inhibiting generation of air bubbles at boundaries between an encapsulation member and various components which contact the encapsulation member.SOLUTION: A semiconductor device comprises a substrate 3, a semiconductor element 5, electrode members 7, an encapsulation member 9 and heat transfer members 11. The substrate 3 is arranged in a case 1. The semiconductor element 5 is placed on one principal surface of the substrate 3. The electrode members 7 are connected to the substrate 3 for conduction with the outside of the semiconductor element 5. The encapsulation member 9 is a member to fill the inside of the case 1. The heat transfer members 11 are connected with part of the substrate 3 or some of the electrode members 7 and are members different from the electrode members 7.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device, and more particularly to a power semiconductor device in which a power semiconductor element is sealed in a resin case.

  2. Description of the Related Art Conventionally, for example, a resin-sealed power semiconductor device in which a semiconductor element is housed in a case and filled with a gel-like synthetic resin and sealed as shown in, for example, Japanese Patent Laid-Open No. 2010-130015 (Patent Document 1). Are known. This type of power semiconductor device is suitably used for an inverter device that performs power conversion, such as a train, a hybrid car, or an electric vehicle. By including the number of power semiconductor devices corresponding to the number of phases of the motor, an inverter device is configured.

  Also, for example, in Japanese Patent Application Laid-Open No. 2008-98584 (Patent Document 2), a liquid insulating oil having sufficient heat resistance at a temperature higher than a heat generation temperature at the time of driving a semiconductor chip is placed in a plastic case housing a semiconductor chip. A power semiconductor device formed by filling and sealing is disclosed. Furthermore, here, as the insulating oil, a mixture of a hygroscopic agent and heat transfer particles having higher thermal conductivity than the insulating oil is used. With this configuration, the power semiconductor device is resistant to thermal shock, good heat dissipation characteristics are obtained, and reliability is improved.

JP 2010-130015 A JP 2008-98584 A

  For example, in the semiconductor devices disclosed in Japanese Patent Application Laid-Open Nos. 2010-130015 and 2008-98584, moisture at the interface between various members such as an insulating substrate and an electrode and a sealing member that touches the member due to heat generation during use is removed. It becomes easy to generate gas. This gas may reduce the creeping withstand voltage of an insulating substrate or the like and may reduce the reliability of the semiconductor device.

  From the viewpoint of suppressing such inconveniences, in Japanese Patent Application Laid-Open No. 2008-98584, the semiconductor element is filled with an insulating oil containing a hygroscopic agent and heat transfer particles, but the heat transfer particles settle in the insulating oil. The heat dissipation effect may be weakened. In the configuration shown in Japanese Patent Application Laid-Open No. 2010-130015, no measures are taken regarding suppression of gas due to internal heat generation during use.

  The present invention has been made in view of the above problems, and an object thereof is generated at an interface between a sealing member and various members that touch the sealing member in a power semiconductor device using a semiconductor element that operates at a high temperature. It is an object of the present invention to provide a semiconductor device whose reliability is improved by suppressing the generation of bubbles.

  The semiconductor device of the present invention includes a substrate, a semiconductor element, an electrode member, a sealing member, and a heat transfer member. The substrate is disposed in the case. The semiconductor element is mounted on one main surface of the substrate. The electrode member is connected to the substrate and conducts with the outside of the semiconductor element. The sealing member fills the case. The heat transfer member is a member different from the electrode member connected to a part of the substrate or a part of the electrode member in the case.

  According to the present invention, both the electrode member and the heat transfer member transmit heat generated during operation of the semiconductor element to the sealing member to warm the sealing member. Since the effect of exhausting the gas in the sealing member to the outside of the sealing member is enhanced by warming the sealing member, the reliability due to bubbles generated at the interface between the sealing member and various members that touch the sealing member Can be suppressed.

Schematic plan view (A) showing the configuration of the power semiconductor device of the first embodiment, a perspective view (B) seen from a dotted line L1 in FIG. 1 (A), and a perspective seen from a dotted line L2 in FIG. 1 (A) It is a figure (C). It is the schematic plan view (A) which shows the structure of the power semiconductor device of a comparative example, and the perspective view (B) seen from the dotted line L1 of FIG. 2 (A). The gas movement mode (A) shown on the perspective view seen from the dotted line L3 in FIG. 2A showing the power semiconductor device of the comparative example, and the dotted line L3 in FIG. 2A showing the power semiconductor device of the comparative example It is the generation | occurrence | production aspect (B) of the bubble represented on the perspective view seen from. FIG. 4 is a perspective view (A) viewed from a dotted line L3 in FIG. 1 (A) showing the power semiconductor device of Embodiment 1, and a gas movement mode (B) shown on the perspective view in FIG. 4 (A). . Schematic plan view (A) showing the configuration of the power semiconductor device of the second embodiment, perspective view (B) seen from the dotted line L1 in FIG. 5 (A), and perspective seen from the dotted line L2 in FIG. 5 (A) It is a figure (C). 6 is a schematic plan view (A) showing the configuration of the power semiconductor device of the third embodiment, a perspective view (B) seen from a dotted line L4 in FIG. 6 (A), and a perspective seen from a dotted line L5 in FIG. 6 (A). FIG. 7C is a perspective view viewed from a dotted line L6 in FIG. 7 is a schematic plan view (A) showing the configuration of the power semiconductor device of the fourth embodiment, a perspective view (B) seen from a dotted line L7 in FIG. 7 (A), and a perspective seen from a dotted line L8 in FIG. 7 (A). FIG. 8C is a perspective view viewed from a dotted line L9 in FIG. Schematic plan view (A) showing the configuration of the power semiconductor device of the fifth embodiment, perspective view (B) seen from dotted line L10 in FIG. 8 (A), and perspective seen from dotted line L11 in FIG. 8 (A) FIG. 9C is a perspective view as seen from the dotted line L12 in FIG. Schematic plan view (A) showing the configuration of the power semiconductor device of Sample 1 of Example 1, Schematic plan view (B) showing the configuration of the power semiconductor device of Sample 2 of Example 1, and Sample 3 of Example 1 A schematic plan view (C) showing the configuration of the power semiconductor device of FIG. 1, a schematic plan view (D) showing the configuration of the power semiconductor device of sample 4 of Example 1, and the configuration of the power semiconductor device of sample 5 of Example 1 A schematic plan view (E) showing, a perspective view (F) showing the dimensions of each part when FIGS. 9 (A) to (E) are viewed from the Y direction, and a point at which the temperature of the uppermost surface of the sealing member is measured And a schematic plan view (G) showing dimensions of each part. Schematic plan view and perspective view (A) showing the configuration of the power semiconductor device of sample 6 of Example 2, and schematic plan view and perspective view (B) showing the configuration of the power semiconductor device of sample 7 of Example 2. FIG. 6 is a schematic plan view and a perspective view (C) showing a configuration of a power semiconductor device of Samples 8, 9, and 10 of Example 2. FIG. A schematic plan view (A) showing the configuration of the power semiconductor device of the sample 11 of Example 3, a perspective view (B) seen from the dotted line L10 in FIG. 11 (A), and a view from the dotted line L11 in FIG. 11 (A) They are a perspective view (C) and a perspective view (D) viewed from a dotted line L12 in FIG. 11 (A). A schematic plan view (A) showing the configuration of the power semiconductor device of the sample 12 of Example 3, a perspective view (B) seen from a dotted line L10 in FIG. 12 (A), and a dotted line L11 in FIG. 12 (A) They are a perspective view (C) and a perspective view (D) viewed from a dotted line L12 in FIG. 12 (A). The schematic plan view (A) showing the configuration of the power semiconductor device of the sample 13 of Example 3, the perspective view (B) seen from the dotted line L10 in FIG. 13 (A), and the dotted line L11 in FIG. 13 (A) They are a perspective view (C) and a perspective view (D) viewed from a dotted line L12 in FIG. 13 (A).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
First, a configuration of a power semiconductor device will be described with reference to FIG. 1 as a configuration of the semiconductor device of the present embodiment. For convenience of explanation, an X direction, a Y direction, and a Z direction are introduced. The X direction and the Y direction mean the horizontal direction and the vertical direction in a plan view, respectively, and the Z direction means a thickness (height) direction that intersects the X direction and the Y direction.

  FIG. 1A is a plan view showing the internal configuration of the power semiconductor device of the present embodiment that does not include a lid 13 described later, and FIG. 1B shows the power of the present embodiment including the lid 13. It is the perspective view (side view) which looked at the internal structure of the semiconductor device from the dotted line L1 in FIG. FIG. 1C is a perspective view (side view) of the internal configuration of the power semiconductor device of the present embodiment including the lid 13 as viewed upward from the dotted line L2 in FIG. It is. In each perspective view, a part of the visible member may be omitted and only a main member (main part) may be extracted, and a plan view may be partly shown for easy understanding of the drawing. There are cases where there is a location that does not match (the same applies to the following figures).

  1A, 1B, 1C, the power semiconductor device of the present embodiment includes a case 1, a substrate 3, a semiconductor element 5, an electrode member 7, and a sealing member 9. And the heat transfer member 11 is mainly included.

  The case 1 is, for example, a rectangular parallelepiped member having a shape capable of accommodating various members such as the substrate 3 constituting the power semiconductor device. Case 1 is formed of a resin material such as poly-phenylene sulfide, for example.

  The substrate 3 is a constituent member that is a base of the power semiconductor device, and is disposed in the case 1. Referring particularly to FIGS. 1B and 1C, the substrate 3 includes an insulating substrate 3a, a back electrode 3b, and a front electrode 3c.

The insulating substrate 3a is a flat plate member made of an insulating material such as ceramics, and has a rectangular shape in plan view, for example, and has a constant thickness in the Z direction. More specifically, as the ceramic material constituting the insulating substrate 3a, for example, aluminum nitride (AlN), silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ), beryllium oxide (BeO), silicon oxide ( Any one selected from the group consisting of SiO ₂ ) and glass ceramics is preferably used. However, the insulating substrate 3a can be made of any material and Z-direction thickness satisfying characteristics such as insulation characteristics, heat dissipation, and linear expansion coefficient required by a power semiconductor device including the same.

  The back electrode 3b is formed so as to be bonded to at least a part of the main surface on the lower side in the Z direction of the insulating substrate 3a, for example, by brazing, and has, for example, a rectangular shape in a plan view and constant in the Z direction. It is the pattern of the thin film which has the thickness of. Similarly, the surface electrode 3c is formed on at least a part of the upper main surface in the Z direction of the insulating substrate 3a so as to be bonded by, for example, brazing (so as to directly cover the upper main surface of the insulating substrate 3a). For example, it is a thin film pattern having a rectangular shape in a plan view and a constant thickness in the Z direction. The back electrode 3b and the front electrode 3c are formed of generally known aluminum, copper, or a metal material combining these. In addition, the metal material which comprises the back surface electrode 3b and the surface electrode 3c may be processed by nickel plating etc. on the surface for oxidation prevention.

  The material constituting the semiconductor element 5 is any one selected from the group consisting of silicon, silicon carbide (SiC), gallium nitride (GaN), and diamond, or a combination of silicon carbide, gallium nitride, and diamond. It may be a composite material. Thereby, the semiconductor element 5 can be used as a power semiconductor element to which a high voltage is applied.

  The semiconductor element 5 has a chip shape (thin plate shape) made of the above-described material, and a plurality of semiconductor elements 5 (see FIG. 1) are spaced apart from each other on one main surface (main surface on the upper side in the Z direction) of the substrate 3, for example. In (A), two rows in each of the X direction and the Y direction, a total of four) are placed. That is, the semiconductor element 5 is bonded by a bonding material such as solder (not shown) such that the main surface on the lower side in the Z direction is in contact with the main surface on the upper side in the Z direction (the surface of the surface electrode 3c). It is installed.

  The semiconductor element 5 is a member constituting an integrated circuit by forming a plurality of fine elements on the surface (upper Z direction in FIG. 1) of a semiconductor chip made of silicon or silicon carbide (SiC). As the fine elements here, for example, power control semiconductor elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors), or so-called power semiconductor elements such as freewheeling diodes are used. However, the present invention is not limited to this, and as a fine element, at least one or more of a number of semiconductor elements whose operating temperature exceeds 125 ° C. may be used.

  The electrode member 7 is disposed in order to electrically connect (conduct) the power semiconductor device (semiconductor element 5) and the external wiring thereof. The electrode member 7 includes a source electrode 7a, a drain electrode 7b, and a gate electrode 7c.

  The source electrode 7 a is electrically connected to the source electrode that constitutes a fine element included in the semiconductor element 5 and is electrically connected to the outside of the semiconductor element 5 including the substrate 3. This corresponds to one large source electrode for the entire power semiconductor device. Similarly, the drain electrode 7 b (gate electrode 7 c) is electrically connected to the drain electrode (gate electrode) constituting a fine element included in the semiconductor element 5, and the semiconductor element 5 including the substrate 3 is connected to the drain electrode 7 b (gate electrode 7 c). This is for electrical connection to the outside, and corresponds to one large drain electrode (gate electrode) for the entire power semiconductor device.

  In FIG. 1, a plurality (three) of surface electrodes 3 c of the substrate 3 are arranged at intervals with respect to the X direction. The source electrode 7a is connected to the leftmost surface electrode 3c, the drain electrode 7b is connected to the central surface electrode 3c, and the gate electrode 7c is connected to the rightmost surface electrode 3c. Therefore, each of the three surface electrodes 3 c has the same potential as each of the electrode members 7. However, here, each of the three surface electrodes 3c constitutes the substrate 3, and the electrode member 7 means each electrode 7a, 7b, 7c connected to the substrate 3 (each of the three surface electrodes 3c). And

  As shown in FIG. 1, each of the source electrode 7a, the drain electrode 7b, and the gate electrode 7c is located above the substrate 3 (surface electrode 3c) from the upper side in the Z direction in the region connected to the surface electrode 3c (lowermost portion in the Z direction). It may have a shape bent at a substantially right angle so as to extend. Thereby, each of the source electrode 7a, the drain electrode 7b, and the gate electrode 7c has a configuration in which most of the regions extend upward in the Z direction.

  The source electrode 7a, the drain electrode 7b, and the gate electrode 7c have a structure in which, for example, nickel plating or the like is performed on the surface of a copper base, and are connected to the surface electrode 3c of the substrate 3 by, for example, ultrasonic bonding. The However, the source electrode 7a, the drain electrode 7b, and the gate electrode 7c can be formed of any material having high electrical conductivity, and are connected to the surface electrode 3c of the substrate 3 by soldering or caulking bonding in addition to ultrasonic bonding. May be.

  Further, the size and position of each electrode 7a, 7b, 7c are not particularly limited, and it is sufficient that the electrodes 7a, 7b, and 7c have a size that allows a desired current to flow. Note that the names of the electrodes 7a to 7c in FIG. 1 are named for convenience of description of the device configuration. For example, the positions and functions of the source electrode and the drain electrode may be replaced with those in FIG. A common electrode may be arranged so as to have both functions of the drain electrode and the drain electrode.

  As shown in FIGS. 1B and 1C, the sealing member 9 is disposed so as to fill the inside of the case 1, and the uppermost surface on the upper side in the Z direction is the uppermost surface of the sealing member in the case 1. 9a. For example, the sealing member 9 is formed by curing a generally known resin material for sealing, but may not necessarily be a resin material. Accordingly, the sealing member 9 is disposed so as to cover at least a part of the surface of each member such as the substrate 3, the semiconductor element 5, and the electrode member 7 disposed in the case 1 while being in contact with each other. .

  The resin material as the sealing member 9 is preferably a material having excellent moldability, curability, storage stability, particularly long-term heat resistance, and good crack resistance. Specifically, as the sealing member 9, for example, a silicone-based resin (a two-component mixed reaction material such as silicone gel) mainly including a thermosetting organopolysiloxane is generally used. Further, as the sealing member 9, an epoxy-based or fluorine-based resin material may be used, and a curing accelerator, an antifoaming agent, an inorganic filler, or the like is added as long as the above-described properties such as moldability are not impaired. It can also be used.

  A plurality of types (two liquids) of which a predetermined amount is weighed are mixed, and the sealing member 9 is first defoamed for 10 minutes under a vacuum of about 13.3 Pa, and then cast into the case 1. Is formed (supplied in the case 1). Thereafter, the sealing member 9 is subjected to secondary degassing for 10 minutes under a vacuum state of 13.3 Pa, and is cured by heating at 70 ° C. for 1 hour.

  The heat transfer member 11 is connected to a part of the substrate 3 (surface electrode 3 c) in the case 1. Specifically, in FIG. 1, two heat transfer members 11 are arranged, one of which is the leftmost surface electrode 3c of the three surface electrodes 3c and the other is the most of the three surface electrodes 3c. Each is connected to the right surface electrode 3c. However, the heat transfer member 11 is a member different from the electrode member 7. That is, basically, the heat transfer member 11 according to the present embodiment does not electrically connect (conduct) the power semiconductor device (semiconductor element 5) and its external wiring. The heat transfer member 11 is sealed so as to be in contact with the sealing member 9 similarly to the electrode member 7 or the like. However, the heat transfer member 11 transfers heat generated during operation of the semiconductor element 5 to the sealing member 9 that is in contact with the heat transfer member 11. Has the ability to communicate.

  As shown in FIG. 1, the heat transfer member 11 is located on the substrate 3 (surface electrode 3 c) above the Z direction (on the substrate 3, for example, on the Z direction upper side) in a region connected to the surface electrode 3 c (lowermost in the Z direction). You may have the shape bent at right angle so that it might extend in the direction which cross | intersects one main surface which is a main surface. The heat transfer member 11 has a region extending upward in the Z direction. However, the heat transfer member 11 may be formed so as to have the planar layer 11a by being bent at a substantially right angle again at the uppermost portion in the Z direction. The flat layer 11a is an uppermost region in the Z direction of the heat transfer member 11 that looks rectangular in FIG. The planar layer 11a extends along a plane (surface) extending in the X direction and the Y direction so as to extend along one main surface (main surface on the upper side in the Z direction) of the substrate 3 in the sealing member 9. The heat transfer member 11 having such a shape is formed by molding using a mold, for example.

  Accordingly, the heat transfer member 11 on the left side in the X direction in FIG. 1 has the planar layer 11a extending rightward in the X direction so as to reach right above the central surface electrode 3c from right above the left surface electrode 3c. Yes. Further, the heat transfer member 11 on the right side in the X direction in FIG. 1 has a planar layer 11a extending to the left side in the X direction so as to reach right above the central surface electrode 3c from right above the right surface electrode 3c.

  In particular, as shown in FIG. 1C, at least a part of the heat transfer member 11 is exposed from the surface of the sealing member 9 in the present embodiment. Specifically, the region on the upper side in the Z direction of the heat transfer member 11, particularly at least a part of the planar layer 11 a, is disposed on the upper side in the Z direction with respect to the uppermost surface 9 a of the sealing member, thereby contacting the sealing member 9. Without being exposed to the outside.

  The material constituting the heat transfer member 11 is preferably any one selected from the group consisting of aluminum, copper, and an alloy of aluminum and copper, for example. That is, conductive member 11 is formed of a metal plate made of, for example, aluminum or copper. If it does in this way, the heat-transfer property by the heat-transfer member 11 can be improved more.

  The heat transfer member 11 is connected to the surface electrode 3c of the substrate 3 by, for example, ultrasonic bonding. However, the heat transfer member 11 can be formed of any material having high electrical conductivity, and may be connected to the surface electrode 3c of the substrate 3 by soldering or caulking bonding, in addition to ultrasonic bonding.

  The power semiconductor device of the present embodiment includes, for example, a lid 13, a base plate 15, and a wire 17 in addition to the above-described members.

  The lid 13 is installed so as to block the uppermost opening in the Z direction of the case 1 so that the region filled with the sealing member 9 inside the case 1 is not exposed to the outside of the case 1. . The lid 13 is preferably a flat plate member basically formed of the same resin material as the case 1.

  Here, in particular, as shown in FIGS. 1B and 1C, the sealing member 9 does not fill the entire case 1 and is slightly below the uppermost portion in the case 1 in the Z direction. It is supplied so as to have an uppermost surface 9a. That is, in the case 1, a gap 14 (a gap due to air or the like) exists between the sealing member uppermost surface 9 a and the lid 13.

  Sealing in the case 1 by the lid 13 is attached after the sealing member 9 is heated and cured, thereby completing a power semiconductor device.

  In FIG. 1, the entire heat transfer member 11 is housed in the case 1 (below the lid 13) and is not exposed to the outside of the case 1 from the lid 13. However, although not shown, for example, from the viewpoint of further improving the heat dissipation of the power semiconductor device, a part of the heat transfer member 11 (region in the upper part of the Z direction) is from the lid 13 (for example, by breaking through a part of the lid 13). The structure exposed to the outside of case 1 may be sufficient.

  The base plate 15 is a member that constitutes the bottom of the case 1 by being disposed so as to close the outer frame constituting the case 1 and the lower side in the Z direction inside the case. That is, the base plate 15 is disposed so as to be connected to the other main surface (the main surface on the lower side in the Z direction) of the substrate 3 opposite to the one main surface. More specifically, the base plate 15 is bonded with a bonding material such as solder (not shown) such that the main surface on the upper side in the Z direction contacts the main surface on the lower side in the Z direction of the substrate 3 (the surface of the back electrode 3b). It is mounted to be. The base plate 15 is a flat plate-like member having a rectangular shape in plan view, for example, and is attached to the bottom of the case 1 with an adhesive or the like (not shown).

  The base plate 15 has a function of radiating heat generated when the semiconductor element 5 is driven from the lower side in the Z direction to the outside of the power semiconductor device. The base plate 15 can have any Z-direction thickness and material satisfying characteristics such as electrical characteristics, heat dissipation, and linear expansion coefficient required by a power semiconductor device including the base plate 15.

  For example, the base plate 15 is generally formed of copper, but may be formed of, for example, molybdenum or tungsten, or an alloy of copper and tungsten, or an alloy of copper and molybdenum (copper molybdenum: CuMo). May be. Alternatively, the base plate 15 may be formed of a ceramic metal material such as a synthetic material of aluminum and silicon carbide (SiC) (aluminum silicon carbide: AlSiC), a synthetic material of silicon and silicon carbide (SiC), Further, it may be formed of synthetic diamond or a composite material of diamond and copper. Further, the base plate 15 may be electrically connected to the semiconductor element 5 or the like by being electrically connected to the back electrode 3b. The base plate 15 formed of such a material can sufficiently satisfy characteristics such as heat dissipation.

  As described above, the sealing member 9 filling the case 1 in the power semiconductor device fills a part of the space surrounded by the side surface of the case 1, the lid 13, and the base plate 15. . Thereby, the sealing member 9 ensures the confidentiality which protects the semiconductor element 5 etc. which are arrange | positioned in the said space from external contamination, etc., or improves the shape precision by the shaping | molding of the whole power semiconductor device. In particular, the heat generated by the semiconductor element 5 and the like is radiated to the outside with high efficiency by the base plate 15.

  For example, the wire 17 electrically connects the semiconductor elements 5 to each other, or the surface electrode 3c other than the semiconductor element 5 and the surface electrode 3c on which the semiconductor element 5 is placed (for example, adjacent to the surface electrode 3c). Are thin wirings connected to the surface of the semiconductor element 5 and the like.

  The wire 17 can be formed of any material that can electrically connect the two regions to be connected. Specifically, the wire 17 is usually formed of a thin wire made of a metal material such as aluminum, copper, or gold. For example, a wire 17 made of copper whose surface is covered with aluminum may be used.

  Although the material used for connecting the wire 17 to the surface electrode 3c or the like is not shown, it is preferably a heat melting member such as solder or silver. The connection method of the wire 17 to the surface electrode 3c and the like is performed by an arbitrary method that enables electrical connection between the wire 17 and the surface electrode 3c and the like. For example, the surface electrode 3c and the wire 17 may be connected to each other by ultrasonic bonding.

  The power semiconductor device of the present embodiment having the above configuration may be used by being attached to a cooling device or the like. In that case, for example, the mounting screw hole 19 may be machined in the case 1 for installation in the cooling device or the like. In FIG. 1A, one mounting screw hole 19 is formed at one end and the other end in the X direction, but there is no particular limitation on the shape and number, and the required mounting strength and product The shape and number can be appropriately determined in consideration of standards and the like.

  More specifically, the power semiconductor device is placed on a cooling fin (not shown) and fixed on the cooling fin by a screw or the like inserted into the mounting screw hole 19. At this time, it is preferable that a heat radiating member such as a heat radiating grease (not shown) is interposed between the power semiconductor device and the cooling fin.

  Next, while explaining the configuration, operation, problem, and the like of the comparative example of FIGS.

  2A is a plan view showing the internal configuration of a comparative power semiconductor device that does not include the lid 13, and FIG. 2B shows the internal configuration of the power semiconductor device according to the present embodiment including the lid 13. As shown in FIG. 3 is a perspective view (side view) of the configuration of FIG. 2 viewed from the dotted line L1 in FIG.

  2A and 2B, the power semiconductor device of the comparative example has basically the same configuration as the power semiconductor device of the present embodiment of FIG. 2 differs from FIG. 1 in that it does not have 11. Since the configuration of the other comparative example (FIG. 2) is almost the same as that of the first embodiment (FIG. 1), the same elements are denoted by the same reference numerals, and the description thereof will not be repeated.

  During the operation of the power semiconductor device, a high voltage is applied to the circuit pattern formed by the semiconductor element 5 and the substrate 3 (surface electrode 3c). In the power semiconductor device of the comparative example of FIG. 2, since the sealing member 9 is formed of silicone gel, a high creeping withstand voltage such as the substrate 3 is secured with a short creeping length even when such a high voltage is applied. can do. In addition, the sealing member 9 can electrically insulate the semiconductor element 5, the electrode member 7, and the wire 17 from each other, for example.

  When a high voltage is applied to the semiconductor element 5 or the like of the power semiconductor device of the comparative example shown in FIG. 2 and the semiconductor element 5 becomes high temperature, the substrate 3 and the electrode member 7, and the sealing member 9 that covers and contacts these As a result, bubbles may be generated at the interface, and as a result, the creeping withstand voltage of the substrate 3 or the like may be reduced, causing a problem that the reliability of the power semiconductor device is reduced. This is because moisture present inside the sealing member 9 and at the interface between the sealing member 9 and each member such as the substrate 3 in contact with the sealing member 9 is vaporized by heat during operation of the semiconductor element 5. This is considered to occur when the amount of gas generated is greater than the gas diffusion rate inside. Such a phenomenon occurs remarkably when a semiconductor element 5 (chip) made of silicon carbide is used and an operation in which the maximum junction temperature (Tjmax) of the semiconductor element 5 exceeds 150 ° C. is performed.

  In order to suppress such a phenomenon, for example, it is conceivable to fill a liquid insulating oil having high heat resistance into the case 1 in which the semiconductor element 5 is housed. There is a possibility that it is difficult to seal and the yield of the product cannot be improved.

  Therefore, in order to suppress such a phenomenon, the inventors of the present invention have conducted extensive research. As a result, the generation of the bubbles due to the temperature rise is caused by the moisture permeability of the silicone gel constituting the sealing member 9 being the temperature of the silicone gel. We paid attention to change depending on.

  3A and 3B are perspective views (side views) seen from the dotted line L3 in FIG. 2A toward the left side of the figure. Referring to FIG. 3A, for example, the region on the relatively right side of the drawing corresponds to a position directly above the semiconductor element 5 that is at a high temperature, so that the sealing member 9 is at a relatively high temperature (this is shown in the figure "H"). On the other hand, for example, since the semiconductor element 5 is not arranged in the region on the left side of the drawing, the sealing member 9 becomes relatively low temperature (this is indicated by “L” in the drawing).

  In the region H in which the sealing member 9 is sufficiently warmed, the gas diffusion rate of the sealing member 9 is large, so that the gas Gs (water vapor) actively flows from above the semiconductor element 5 into the sealing member 9 as indicated by arrows. Is moved upward in the Z direction. That is, the gas Gs generated by the vaporization of moisture due to the high-temperature operation of the semiconductor element 5 actively moves above the sealing member 9 and is discharged to the outside of the sealing member 9.

  On the other hand, in the region L where the sealing member 9 is cooled, the gas diffusion rate of the sealing member 9 is small, and the gas Gs generated by the vaporization of moisture due to the high temperature operation of the semiconductor element 5 moves in the sealing member 9. It is hard to be discharged outside. Therefore, as shown in FIG. 3B, bubbles 25 are likely to be generated particularly in the interface between the sealing member 9 and the substrate 3 in the low temperature region 21 of the sealing member 9.

  Therefore, as in FIGS. 3A and 3B, see FIGS. 4A and 4B which are perspective views (side views) seen from the dotted line L3 in FIG. Then, as shown in the present embodiment (FIG. 1), in the case 1 (that is, in contact with the sealing member 9), the heat transfer member 11 (here, like the electrode member 7) is partially attached to the substrate 3. Are arranged so as to be connected.

  Thereby, heat generated during operation of the semiconductor element 5 in the case 1 is transmitted to the heat transfer member 11, and the sealing member 9 is warmed by being transferred from the heat transfer member 11 to the sealing member 9 with high efficiency. For this reason, even if bubbles 25 are generated by heating at the interface between the sealing member 9 and various members such as the substrate 3, it quickly diffuses and moves upward in the Z direction, as shown by the thick arrows in FIG. Even in the low temperature region 21, the gas Gs is discharged to the outside of the sealing member 9. Accordingly, it is possible to suppress a decrease in creeping withstand voltage of the substrate 3 or the like due to the bubbles 25 staying in the vicinity of the interface even in the low temperature region 21 and to improve the reliability of the power semiconductor device.

  In the present embodiment, since the sealing member 9 is heated using the heat generated by driving the semiconductor element 5, it is not necessary to supply, for example, power for heating the sealing member 9 from the outside. For this reason, it is possible to warm the sealing member 9 at a low cost and with high efficiency, and to suppress the occurrence of problems due to the retention of the bubbles 25.

  The heat transfer member 11 extends upward from the surface of the substrate 3 in the Z direction. For this reason, the inside of the sealing member 9 can be uniformly warmed from the lower side to the uppermost part in the Z direction, and the bubbles 25 can be guided to the uppermost surface of the sealing member 9 with higher efficiency.

  Further, at least a part of the heat transfer member 11 (the uppermost portion in the Z direction) is exposed from the sealing member uppermost surface 9 a which is the surface of the sealing member 9. This is because the resin material constituting the sealing member 9 has a low thermal conductivity, so that the temperature of the sealing member 9 is maximized in the vicinity of the heat transfer member 11 to maximize the characteristics. .

  That is, if the heat transfer member 11 is exposed from the sealing member uppermost surface 9a of the sealing member 9, the heat transfer member 11 is present in the vicinity of the sealing member uppermost surface 9a. The temperature of the sealing member 9 in the vicinity of 9a increases. In particular, referring to FIGS. 4A and 4B, the transmittance of gas such as water vapor generated in the vicinity of the heat transfer member 11 in the sealing member 9 is further increased, and the sealing is performed with higher efficiency. The gas can be moved to reach the member uppermost surface 9a. In other words, the sealing member 9 in the vicinity of the heat transfer member 11 can function as a highly efficient gas discharge path.

  Further, in the present embodiment, the heat transfer member 11 has the planar layer 11a that extends in the X direction and the Y direction, so that the volume of the heat transfer member 11 is increased and the heat capacity thereof is increased as compared with the case where it does not exist. . For this reason, the heat dissipation effect by the heat transfer member 11 is enhanced. Therefore, it is possible to suppress the vaporization of moisture due to heating, and it is possible to suppress a decrease in reliability of the power semiconductor device due to a temperature rise during driving.

  The electrode member 7 also has a function of transferring heat to the sealing member 9 in the same manner as the heat transfer member 11, but by having the heat transfer member 11 (which does not contribute to electrical conduction) separately from the heat transfer member 11, The efficiency of diffusing heat can be further increased.

  However, in the power semiconductor device of the present embodiment as described above, the electrode member 7 has a plurality of members such as the source electrode 7a, the drain electrode 7b, and the gate electrode 7c. And it is preferable that the heat transfer member 11 is arrange | positioned in the position where the shortest distance with the shortest distance with the said heat transfer member 11 is 25 mm or less among these several electrode members 7 (7a, 7b, 7c). .

  Here, when there are a plurality of heat transfer members 11, there are a plurality of shortest distances between each heat transfer member 11 and the shortest distance from the heat transfer member 11. Of the longest distances, the shortest distance is more preferably 25 mm or less. Here, the shortest distance means the shortest distance considered in the three directions (three dimensions) of the X direction, the Y direction, and the Z direction.

  That is, referring to FIG. 1A again, for example, the right heat transfer member 11 in FIG. 1 has a distance D of 25 mm or less with respect to the gate electrode 7c which is the electrode member 7 disposed at the closest position. It is preferable. Similarly, for example, the heat transfer member 11 on the left side of FIG. 1A preferably has a shortest distance of 25 mm or less from the source electrode 7a, which is the electrode member 7 disposed at the closest position. Thereby, the heat transfer member 11 enhances the effect of transferring heat to the sealing member 9 in cooperation with the electrode member 7 having the same function. Therefore, the effect of suppressing the decrease in creeping withstand voltage of the substrate 3 and the effect of discharging the gas Gs due to the heat transfer member 11 warming the sealing member 9 are further enhanced.

  Furthermore, in the power semiconductor device according to the present embodiment, the temperature of the surface (upper side in the Z direction) during the operation of the semiconductor element 5 (chip) and one main surface of the substrate 3 in the sealing member 9 are driven. It is preferable that the difference from the minimum value of the temperature of the surface on the same side as the surface (upper side in the Z direction) (that is, the sealing member uppermost surface 9a) is 120 ° C. or less. In other words, referring again to FIG. 1B, the temperature T1 of the upper surface of the semiconductor element 5 (on which many fine elements are mounted) in the Z direction and the minimum value T2 (T1) of the uppermost surface 9a of the sealing member. > T2) is 120 ° C. or less. In this way, the heat transfer member 11 is sufficiently equipped with a function of heating the sealing member 9, so that it can be said that the reliability of the power semiconductor device can be improved. These features will be described later in detail as examples.

  The power semiconductor device described above is a so-called case type power semiconductor device formed by the base plate 15 and the substrate 3 including the insulating substrate 3a thereon. However, the present invention is not limited to this. For example, a so-called case-type power module structure in which a metallic substrate is placed on the base plate 15 with an organic insulating film interposed therebetween also achieves the same effect as the above-described embodiment. be able to.

(Embodiment 2)
FIGS. 5A, 5B, and 5C show the power semiconductor device of the second embodiment in the same manner as in FIGS. 1A, 1B, and 1C of the first embodiment (same as in FIGS. It shows an aspect as seen from the location and from the same direction. Referring to FIGS. 5A, 5B, and 5C, the power semiconductor device of the present embodiment has basically the same configuration as the power semiconductor device of the first embodiment of FIG. However, the heat transfer member 11 is not exposed at all from the uppermost surface 9 a of the sealing member 9, and the entire surface including the flat layer 11 a is buried in the sealing member 9. In this respect, FIG. 5 is different from FIG. 1, but the configuration of the present embodiment (FIG. 5) other than this is almost the same as the configuration of the first embodiment (FIG. 1). The same reference numerals are given and description thereof will not be repeated.

  As described above, when the heat transfer member 11 is partially exposed from the surface of the sealing member 9, the effect of uniformly heating the sealing member 9 to the uppermost portion is increased, and bubbles generated in the sealing member 9 and the like are generated. 25 (see FIG. 3B) can be enhanced. However, it is not an essential condition to expose the heat transfer member 11 on the surface 9a of the sealing member 9. As long as the heat transfer member 11 has gas diffusibility necessary for the semiconductor device, the heat transfer member as in the present embodiment. 11 may be embedded in the sealing member 9.

(Embodiment 3)
6A is a plan view similar to FIG. 1A, and FIG. 6B is a perspective view seen from the dotted line L4 in FIG. 6A upward. 6C is a perspective view seen from the dotted line L5 in FIG. 6A toward the upper side of the figure, and FIG. 6D is a perspective view seen from the dotted line L6 in FIG. 6A toward the left side of the figure. .

  Referring to FIGS. 6A, 6B, 6C, and 6D, the power semiconductor device of the present embodiment is basically similar in configuration to the power semiconductor device of the first embodiment of FIG. However, instead of the heat transfer member 11 in which the metal plate is bent as in the first embodiment, a heat transfer member 12 that is a ribbon wire is used. In this respect, FIG. 6 differs from FIG. 1, but the configuration of this embodiment (FIG. 6) other than this is almost the same as the configuration of Embodiment 1 (FIG. 1). The same reference numerals are given and description thereof will not be repeated.

  The heat transfer member 12 is not particularly limited in material and shape as long as the semiconductor device has heat transfer properties required by the semiconductor device. That is, wire wiring or the like can be substituted for the heat transfer member 12. As an example, the ribbon member made of aluminum is used for the heat transfer member 12 of FIG. However, as the heat transfer member 12, a metal wire having a circular cross section formed of, for example, aluminum, copper, or gold may be used, or a copper wire whose surface is covered with aluminum may be used. May be. Alternatively, the heat transfer member 12 may be formed of a carbon-based composite material (carbon is a main constituent material) such as a carbon nanotube. For example, since the carbon nanotube has anisotropy in thermal conductivity, if this is used, the heat transfer member 12 can preferentially heat the sealing member 9 in a necessary direction, and the temperature distribution of the sealing member 9 can be increased. It can be controlled more precisely.

  As shown in FIG. 6C, both ends of the heat transfer member 12 arranged on the lower side in the Y direction in FIG. 6A are mutually on the X direction on the surface electrode 3c on the upper side of the substrate 3. The heat transfer member 12 forms a loop between the substrate 3 (surface electrode 3c) by being connected to two points spaced apart.

  As shown in FIG. 6D, the heat transfer members 12 arranged on the left and right sides in the X direction in FIG. 6A are basically the same as described above. However, in FIG. 6D, two ribbon wires as the heat transfer members 12 are arranged so as to at least partially overlap each other in the Z direction, and are spaced from each other in the Y direction. A loop is formed by being connected to two points. A certain amount of space is maintained between the two heat transfer members 12 in the Z direction, and the two heat transfer members 12 are electrically insulated.

  If the ribbon wire of the heat transfer member 12 is doubled in the Z direction as shown in FIG. 6D, the heat transfer efficiency of the heat transfer member 12 can be further increased. Furthermore, although not shown, if the semiconductor device has a necessary heat transfer property, the ribbon wire used for the heat transfer member 12 does not need to be connected to the substrate 3 (surface electrode 3c) so as to form a loop. Only one of the pair of end portions may be connected to the substrate 3 (surface electrode 3c). Although not shown, even when a ribbon wire-shaped heat transfer member 12 is used as in the present embodiment, a part of the heat transfer member 11 is sealed as in the heat transfer member 11 of the first embodiment. It is also possible to take a structure exposed above the surface of the member 9 in the Z direction.

  Furthermore, also about the heat transfer member 12 of this Embodiment, the shortest distance with the electrode member 7 with the shortest distance with the heat transfer member 12 among the several electrode members 7 similarly to the heat transfer member 11 of Embodiment 1. FIG. Is preferably disposed at a position of 25 mm or less. Also in the present embodiment, it is preferable that the difference between the surface temperature T1 of the semiconductor element 5 and the minimum temperature T2 of the sealing member uppermost surface 9a is 120 ° C. or less.

Next, the effect of this Embodiment is demonstrated.
The heat transfer member 12 as a ribbon wire of the present embodiment does not require the use of a mold at the time of formation unlike the heat transfer member 11 as a metal plate, and therefore the construction period can be shortened. Moreover, the sealing member 9 can be heated more efficiently by using inexpensive and high thermal conductivity aluminum ribbon wire as the heat transfer member 12. Furthermore, since the heat transfer member 12 can be installed in a necessary part more easily than the heat transfer member 11, the degree of freedom in designing the entire power semiconductor device can be increased.

  In addition, if a loop is formed between the heat transfer member 12 and the substrate 3, the heat transfer member 12 can be more stably fixed to the substrate 3.

(Embodiment 4)
FIG. 7A is a plan view similar to FIG. 1A, and FIG. 7B is a perspective view seen from the dotted line L7 in FIG. 7A upward. 7C is a perspective view seen from the dotted line L8 in FIG. 7A toward the upper side of the figure, and FIG. 7D is a perspective view seen from the dotted line L9 in FIG. 7A toward the left side of the figure. .

  Referring to FIGS. 7A, 7B, 7C, and 7D, the power semiconductor device of the present embodiment is basically similar in configuration to the power semiconductor device of the first embodiment of FIG. However, the heat transfer member 11 has a smaller shape than the first embodiment in which the heat transfer member 11 does not have the planar layer 11 a as in the first embodiment, and a large number of these are arranged on one substrate 3. . In this respect, FIG. 7 differs from FIG. 1, but the configuration of the present embodiment (FIG. 7) other than this is substantially the same as the configuration of the first embodiment (FIG. 1). The same reference numerals are given and description thereof will not be repeated.

  7A and 7C, four heat transfer members 11 are provided in a region between one and the other of the semiconductor elements 5 arranged in two rows in the Y direction, and are spaced from each other in the X direction. Has been placed. 7A and 7D, among the four heat transfer members 11, the leftmost and rightmost heat transfer members 11 in the X direction are spaced apart from each other in the Y direction ( There is a further heat transfer member 11 (downward in the Y direction). Therefore, the power semiconductor device of FIG. 7 has a total of six heat transfer members 11 on one substrate 3.

  Similarly to the heat transfer member 11 of the first embodiment, the heat transfer member 11 of the present embodiment has a Z-direction from the top of the substrate 3 (surface electrode 3c) in the region (the lowest part in the Z direction) connected to the surface electrode 3c. It has a shape bent substantially at right angles so as to extend in the upper direction (the direction intersecting one main surface, for example, the main surface on the upper side in the Z direction) of the substrate 3. However, the heat transfer member 11 does not have a bent portion at the top in the Z direction and does not have a flat layer 11a. For this reason, the heat transfer member 11 has a substantially columnar shape as a whole. In addition, it is preferable that a part of the heat transfer member 11 of the present embodiment is exposed outside the sealing member uppermost surface 9a as in the first embodiment.

Next, the effect of this Embodiment is demonstrated.
For example, even when a large heat transfer member 11 having a flat layer 11a (having a large heat capacity) cannot be installed as in the first embodiment due to layout reasons, etc., as in the present embodiment, a columnar transfer is not possible. A function of supplying heat to the sealing member 9 in the same manner as the heat transfer member 11 of the first embodiment by disposing a plurality of the heat members 11 (for example, six for one substrate 3) spaced apart from each other. An effect can be obtained.

  Also in this embodiment, as in the other embodiments, the shortest distance from the electrode member 7 having the shortest distance to the heat transfer member 12 among the plurality of electrode members 7 is arranged at a position of 25 mm or less. Is preferred. Also in the present embodiment, it is preferable that the difference between the surface temperature T1 of the semiconductor element 5 and the minimum temperature T2 of the sealing member uppermost surface 9a is 120 ° C. or less.

  The heat transfer member 11 of the present embodiment is a member different from the electrode member 7 such as the source electrode 7a as in the other embodiments. However, as in the present embodiment, a large number of heat transfer members 11 arranged in a single power semiconductor device may be members that can conduct electricity to the outside of the power semiconductor element (semiconductor element 5). However, as described above, the heat transfer member 11 according to the present embodiment preferably has a restriction such that the shortest distance from the electrode member 7 is 25 mm or less. Therefore, for example, another electrode member 7 as viewed from one electrode member 7 of a normal semiconductor device (as a comparative example) having a plurality of electrode members 7 is included in the heat transfer member 11 of the present embodiment. Shall not.

  As described above, when the heat transfer member 11 is a member that can conduct electricity with the outside of the power semiconductor element (semiconductor element 5), the degree of freedom in designing the electrode of the power semiconductor device can be increased.

(Embodiment 5)
FIG. 8A is a plan view similar to FIG. 1A, and FIG. 8B is a perspective view seen from the dotted line L10 in FIG. 8A upward. 8C is a perspective view seen from the dotted line L11 in FIG. 8A toward the left side of the figure, and FIG. 8D is a perspective view seen from the dotted line L12 in FIG. 8A toward the left side of the figure. .

  Referring to FIGS. 8A, 8B, 8C, and 8D, the basic configuration of the power semiconductor device of the present embodiment is the same as that of the power semiconductor device of the first embodiment shown in FIG. However, in the present embodiment, the case 1 is large, and the number of substrates 3 and semiconductor elements 5 housed in the case 1 is increased compared to the first embodiment.

  Specifically, in FIG. 8, a plurality of (for example, a total of eight) substrates 3 are arranged in a storage space inside one large case 1 at intervals. That is, four rows 3 in the X direction and two rows in the Y direction are arranged in a matrix, and the four substrates 3 on the upper side in the Y direction in FIG. 8A are the substrate 31, the substrate 32, the substrate 33, The four substrates 3 on the lower stage in the Y direction in FIG. 8A are a substrate 35, a substrate 36, a substrate 37, and a substrate 38 in this order from the left side.

  As shown in FIGS. 8B, 8 </ b> C, and 8 </ b> D, similarly to the substrate 3, the substrates 31 to 38 include the insulating substrates 31 a to 38 a and the back electrode 31 b on the main surface on the lower side in the Z direction. To 38b and surface electrodes 31c to 38c on the main surface on the upper side in the Z direction of the insulating substrates 31a to 38a.

  Each of the substrates 31 to 38 is mounted with, for example, four semiconductor elements 5 and electrically connected using the wires 17 in the same manner as the substrate 3 in the first embodiment. A single large base plate 15 is bonded so as to be in contact with all the back electrodes 31b to 38b of these substrates 31 to 38, whereby a power semiconductor device including the large case 1 is configured. In FIG. 8, a plurality of small heat transfer members 11 similar to those in the fourth embodiment are arranged with a space therebetween, but this is not restrictive, and the present embodiment is also implemented as long as layout is possible. A large heat transfer member 11 having the same flat layer 11a as in the first embodiment may be connected.

  In FIG. 8, a single source electrode 7a and drain electrode 7b are connected to the respective substrates 31 to 38 (surface electrodes 3c thereof). The source electrode 7a can be electrically connected to the outside of the power semiconductor device by, for example, three source terminals 7a1, 7a2 and 7a3 connected thereto. Similarly, the drain electrode 7b can be electrically connected to the outside of the power semiconductor device by, for example, three drain terminals 7b1, 7b2, and 7b3 connected thereto. The source terminals 7a1, 7a2, 7a3 and the drain terminals 7b1, 7b2, 7b3 are arranged so as to be exposed to the outside of the case 1. On the other hand, one gate electrode 7c is connected to each of the substrates 31 to 38 so as to extend upward in the Z direction so as to be exposed outside the case 1.

  FIG. 8 is different from FIG. 1 in the above points, but the configuration of the present embodiment (FIG. 8) other than this is substantially the same as the configuration of Embodiment 1 (FIG. 1), and therefore the same elements are used. Are denoted by the same reference numerals, and the description thereof will not be repeated.

Next, the effect of this Embodiment is demonstrated.
In a power module for trains, for example, for driving an inverter through which a large current flows, a large power semiconductor device (package having a large case 1) may be used as in this embodiment. In this case, the variation in the temperature distribution in the sealing member 9 becomes even larger than that in the first embodiment, and a region where gas diffusion is difficult such as the low temperature region 21 in FIGS. 3 and 4 may be expanded. There is. For this reason, if the sealing member 9 is heated using the heat transfer member 11 for a large-sized power semiconductor device as in the present embodiment, the effect is much greater than when the heat transfer member 11 is not present. Can be obtained.

  Also in this embodiment, as in the other embodiments, the shortest distance from the electrode member 7 having the shortest distance to the heat transfer member 12 among the plurality of electrode members 7 is arranged at a position of 25 mm or less. Is preferred. Also in the present embodiment, it is preferable that the difference between the surface temperature T1 of the semiconductor element 5 and the minimum temperature T2 of the sealing member uppermost surface 9a is 120 ° C. or less.

  The heat transfer member 11 according to the present embodiment is a member different from the electrode member 7 such as the source electrode 7a as in the first to third embodiments. However, as in the present embodiment, a large number of heat transfer members 11 arranged in a single power semiconductor device are members that can be electrically connected to the outside of the power semiconductor element (semiconductor element 5) (similar to the fourth embodiment). It may be. However, as described above, the heat transfer member 11 according to the present embodiment preferably has a restriction such that the shortest distance from the electrode member 7 is 25 mm or less. Therefore, for example, another electrode member 7 as viewed from one electrode member 7 of a normal semiconductor device (as a comparative example) having a plurality of electrode members 7 is included in the heat transfer member 11 of the present embodiment. Shall not.

  As described above, when the heat transfer member 11 is a member that can conduct electricity with the outside of the power semiconductor element (semiconductor element 5), the degree of freedom in designing the electrode of the power semiconductor device can be increased.

  In this example, thermal diffusion in the sealing member 9 when the power semiconductor device having the small heat transfer member 11 (not having the planar layer 11a) as shown in the fourth embodiment is driven, We are also investigating creepage insulation resistance (reliability of power semiconductor devices). First, the sample used for the investigation of this example will be described with reference to FIGS.

  Referring to FIGS. 9A to 9E, these correspond to samples 1, 2, 3, 4, and 5 of the power semiconductor device for investigation, respectively. Specifically, Sample 1 in FIG. 9A is a power semiconductor device of a comparative example shown in FIG. 2A and has a configuration without the heat transfer member 11. In the sample 2 of FIG. 9B, two small heat transfer members 11 shown in the fourth embodiment are connected to the position shown in the drawing (on the surface electrode 3c) with respect to the sample 1. Here, the distance is the longest among a plurality of the shortest distances D described below (the same applies to the following samples). The heat transfer of the gate electrode 7c as the electrode member 7 is the shortest (on the right side in the figure). The shortest distance D with the member 11 is 40 mm.

  Similarly, in the sample 3 of FIG. 9C, two small heat transfer members 11 shown in the fourth embodiment are connected to the sample 1 at the position shown on the drawing (on the surface electrode 3c). Here, the shortest distance D between the gate electrode 7c as the electrode member 7 and the heat transfer member 11 with the shortest distance (on the right side in the drawing) is 25 mm. In the sample 4 in FIG. 9D, four small heat transfer members 11 shown in the fourth embodiment are connected to the sample 1 at the position shown on the drawing (on the surface electrode 3c). Here, the shortest distance D between the gate electrode 7c as the electrode member 7 and the heat transfer member 11 with the shortest distance (upper right in the drawing) is 20 mm. In the sample 5 of FIG. 9E, six small heat transfer members 11 shown in the fourth embodiment are connected to the sample 1 at the position shown on the drawing (on the surface electrode 3c). Here, the shortest distance D between the gate electrode 7c as the electrode member 7 and the heat transfer member 11 with the shortest distance (upper right in the drawing) is 20 mm.

  With reference to FIG. 9 (F), the height (distance) regarding the Z direction from the Z direction uppermost part of the wire 17 to the sealing member uppermost surface 9a is set to 25 mm in any of the samples 1 to 5. In any of Samples 1 to 5, the height (distance) in the Z direction from the uppermost portion in the Z direction of the surface electrode 3c to the uppermost surface 9a of the sealing member is set to 28 mm.

In the substrates 3 of the samples 1 to 5, the insulating substrate 3a was formed of silicon nitride (Si ₃ N ₄ ), and the back surface and the surface electrodes 3b and 3c were formed as a copper pattern. The semiconductor element 5 (chip) bonded so as to be in contact with the surface electrode 3c is formed of silicon carbide (SiC), and a number of MOSFETs and Schottky barrier diodes are mounted on the surface thereof. Base plate 15 joined so as to be in contact with back electrode 3b was formed of aluminum silicon carbide. The electrode member 7 was connected on the surface electrode 3c by ultrasonic bonding. The wire 17 was connected to the surface electrode 3c and the semiconductor element 5 by ultrasonic bonding.

  A case in which the case 1 made of polyphenylene sulfide formed so as to surround the periphery of the base plate 15 in plan view is bonded to the base plate 15 so that the substrate 3 and the semiconductor element 5 are arranged in the case 1 became. The base plate 15 and the case 1 were bonded with a silicone adhesive. Here, after the nickel-plated copper heat transfer member 11 is connected to the substrate 3 as in each of the samples 1 to 5 by ultrasonic bonding, the substrate 3 and the semiconductor element 5 are cased by the supply of the sealing member 9. 1 was sealed.

  In this embodiment, a base polymer (weight average molecular weight 38700) is used as the sealing resin as the sealing member 9, and a complex of platinum and divinyltetramethyldisiloxane (the platinum metal in the composition is expressed in weight units). A silicone gel composition was prepared by uniformly mixing (amount of 5 ppm). After the silicone gel composition was vacuum degassed, the silicone gel composition was poured into an intermediate power semiconductor device in which the base plate 15 and the case 1 were bonded, and heated at 70 ° C. for 60 minutes.

  This silicone gel had a penetration of 40 and tan δ (0.1 Hz) of 0.30. Here, tan δ is called a loss factor and is a value that can be measured by a rheometer. The smaller this value, the better the shock absorption.

  By attaching the lid 13 to the power semiconductor device in the above intermediate stage, samples 1 to 5 of the power semiconductor device were formed, and a reliability test was performed on the samples 1 to 5. Next, the reliability test method will be described.

  The reliability test of the power semiconductor device was performed by putting the samples 1 to 5 into a constant temperature and humidity chamber, and then performing a power cycle test and evaluating the insulation resistance of the samples 1 to 5 thereafter. In the constant temperature and humidity chamber, the power semiconductor device is loaded for 16 hours under a temperature and humidity condition of 85 ° C. and 85%, and then the condensed water is dried and removed at 85 ° C. for 60 minutes. After removing condensed water, the power semiconductor device was cooled to room temperature and a power cycle test was performed. A high voltage of 8000 V was applied between the substrate 3 and the base plate 15 every specified number of times during the power cycle test, and the insulation resistance was measured. The power cycle test was conducted up to 300 k cycles, and the reliability of Samples 1 to 5 was confirmed by confirming the presence or absence of creeping breakdown due to the deterioration of the insulation resistance when the high voltage was applied.

  With reference to FIG. 9 (G), the temperature of the sealing member 9 is one of four points where the X coordinate shown in FIG. 9 (G) is 1 to 4, and the Y coordinate is 3 points. The temperature of the sealing member uppermost surface 9a at a total of 12 points (12 places) was measured using a thermocouple. The distance between adjacent X coordinates 1, 2, 3, 4 and the distance between adjacent Y coordinates 1, 2, 3 are 25 mm. In the following, among the points at which the temperature of the uppermost surface of the sealing member 9 is measured, for example, a point having an X coordinate of 1 and a Y coordinate of 2 will be expressed as (1, 2).

The temperature during continuous operation (Tj (op)) was measured using a MOSFET temperature sensor. The module was operated at the rated 6500 V, the surface temperature (chip temperature) of the semiconductor element 5 at this time was measured, and the operation was controlled so that the chip temperature (T _OPmax ) at the rated operation did not exceed 175 ° C. Further, the temperature of each point of the sealing member 9 when the module was operated at a high voltage of 6500 V was examined. Therefore, basically, the temperature of the surface of the semiconductor element 5 at the time of measuring the temperature of the sealing member uppermost surface 9a is 175 ° C., and this temperature and the temperature of each point (12 points) of the sealing member uppermost surface 9a I examined the difference. The results are shown in Table 1 below.

  “Thermocouple temperature” in Table 1 indicates a value obtained by measuring the temperature at each point (12 points) of the sealing member uppermost surface 9a with a thermocouple, and “temperature difference from the chip” is the uppermost surface of the sealing member. A temperature difference between each point 9a (12 points) and the surface of the semiconductor element 5 (175 ° C.) is shown. The underline in the table indicates the minimum temperature measured for each sample.

  Referring to Table 1, in sample 1 corresponding to the comparative example (FIG. 2), that is, in which no heat transfer member 11 is provided, the temperature in (4, 3) is 47 ° C., and the temperature difference from the chip is 128 ° C. became. When the power cycle test was performed for 120 k cycles, generation of bubbles and traces of dielectric breakdown were confirmed in the portion of the substrate 3 just below the Z direction at the position (4, 3).

  In the power semiconductor device of sample 1, the surrounding moisture is vaporized by heating of the semiconductor element 5, but since the heat transfer member 11 is not arranged and the temperature of the sealing member 9 is not raised, the surroundings are faster than the vaporization rate. It is considered that bubbles are generated because the diffusion rate of the silicone gel is small. As a result, it is considered that dielectric breakdown occurred at the site where bubbles were generated during the subsequent evaluation of insulation resistance. Moreover, since the surface temperature of the silicone gel is low at the site where the bubbles are generated, it is considered that the moisture permeability of the silicone gel in this region is particularly lower than that in other areas, which is also a factor in generating bubbles in this portion.

  Sample 2 is an example in which two heat transfer members 11 of the present invention are connected. In this example, the number of power cycles until breakdown is increased to 210 k cycles as compared to sample 1, and the chip And the temperature difference is reduced to 123 ° C. That is, the arrangement of the heat transfer member 11 raises the temperature of the sealing member 9 as compared to the sample 1, and the bubbles are less likely to stay in the sealing member 9 or the like. It is done. In other words, it can be said that the reliability of Sample 2 is improved as compared to Sample 1.

  On the other hand, the samples 3, 4 and 5 are provided with the heat transfer member 11, but the distance between the heat transfer member 11 and the gate electrode 7c is shorter than the sample 2 (40 mm) (25 mm or less). In this way, dielectric breakdown does not occur after a predetermined number of power cycles, and the reliability is further improved as compared with sample 2. In addition, the temperature difference with the chip at this time is all 120 ° C. or less, and the temperature of the sealing member 9 is further increased from that of the sample 2, so that the sealing member 9 is also in the low temperature region 21 (see FIG. 3). It is thought that the diffusion of bubbles in the interior further progressed and the dielectric breakdown was suppressed.

  From the above results, if the distance between the heat transfer member 11 and the nearest electrode 7 (here, the gate electrode 7c) is 25 mm or less, the reliability can be ensured even if the temperature is raised during driving of the power semiconductor device. Became clear. It has also been clarified that the reliability of the power semiconductor device can be ensured if the difference between the surface temperature of the silicone gel constituting the sealing member 9 and the chip temperature is 120 ° C. or less.

  Here, among the plurality of electrode members 7, a desired effect is achieved particularly by setting the distance between the gate electrode 7 c and the heat transfer member 11 to 25 mm or less. The reason why the gate electrode 7c is focused here is that the gate electrode 7c has a smaller cross-sectional area than the source electrode 7a and the like, and the current value flowing therethrough is small. Therefore, it is considered that the sealing member 9 tends to be in a low temperature region near the gate electrode 7c, and bubbles are likely to be generated, as compared with the vicinity of the other electrodes 7a and 7b.

  Therefore, the temperature of the sealing member 9 near the gate electrode 7c is arranged by arranging the heat transfer member 11 near the gate electrode 7c (position of 25 mm or less) where the temperature is less likely to rise compared to the other electrodes 7a and 7b. It can be considered that the reliability can be improved because it can be increased more efficiently.

  Further, as a different idea from the above, by providing the heat transfer member 11 in a region near the electrode member 7 (25 mm or less) where the sealing member 9 is relatively easy to warm, heat from the electrode member 7 is transferred. 11 can be transmitted to the sealing member 9 more efficiently. From this point of view, it can be said that it is preferable to provide the heat transfer member 11 near the electrode member 7 (25 mm or less).

  In the present embodiment, when a large-sized heat transfer member 11 having a flat layer 11a or a power semiconductor device having a heat transfer member 12 as a ribbon wire is driven as shown in the first to third embodiments. The heat diffusion in the sealing member 9 and the creeping insulation resistance are examined. First, a sample used for the investigation of this example will be described with reference to FIGS.

  Referring to FIGS. 10A to 10C, these correspond to samples 6, 7, 8 to 10 of the power semiconductor device for investigation, respectively. Specifically, the sample 6 in FIG. 10A is the power semiconductor device of the first embodiment shown in FIGS. 1A and 1C, and the heat transfer member 11 exposed from the sealing member uppermost surface 9a. It is the structure which has. A sample 7 in FIG. 10B is the power semiconductor device of the second embodiment shown in FIGS. 5A and 5C, and has a configuration having the heat transfer member 11 that is not exposed from the sealing member uppermost surface 9a. . Samples 8, 9, and 10 in FIG. 10C are the power semiconductor device of Embodiment 3 shown in FIGS. 6A, 6C, and 6D, and have a heat transfer member 12 as a ribbon wire. It is a configuration.

  In samples 6 and 7, the shortest distance D between the gate electrode 7c and the closest heat transfer member 11 is 25 mm, and in sample 8, the shortest distance D between two adjacent heat transfer members 12 is 35 mm. In the sample 9, the D is 25 mm, and in the sample 10, the D is 15 mm.

  The materials of the various members constituting these samples, the method for producing each sample, and the method for reliability testing are the same as in Example 1 except that the heat transfer members 12 of samples 8 to 10 are formed of aluminum. Therefore, the description will not be repeated. Table 2 below shows the results of the same investigation as Samples 1 to 5 for Samples 6 to 10.

  Referring to Table 2, in all of Samples 6 to 8, dielectric breakdown did not occur after a predetermined number of power cycles, and reliability was ensured. In addition, the temperature difference between these chips is 120 ° C. or less as in the first embodiment.

  From the above results, in particular, if the distance between the heat transfer member and the closest electrode 7 (here, the gate electrode 7c) is 25 mm or less, even if the heat transfer member 11 is provided with the flat layer 11a, the embodiment It became clear that high reliability can be ensured similarly to Samples 3 to 5 of 1. In particular, if the distance between the heat transfer member and the closest electrode 7 (here, the gate electrode 7c) is 25 mm or less, even if the type of the heat transfer member is changed from the heat transfer member 11 to the heat transfer member 12. (In other words, in the samples 9 and 10 using the ribbon wire as the heat transfer member), it became clear that high reliability can be ensured similarly to the samples 3 to 5 of the first embodiment. It has also been clarified that the reliability of the power semiconductor measures can be ensured if the difference between the surface temperature of the silicone gel constituting the sealing member 9 and the chip temperature is 120 ° C. or less.

  The difference between the chip temperature and the sample 6 is the smallest in the sample 6 because the heat transfer member 11 is exposed from the surface of the sealing member 9 and thus the surface of the sealing member 9 is more easily heated. it is conceivable that. Although the structure like the sample 7 (Embodiment 2) in which the entirety of the heat transfer member 11 is embedded in the sealing member 9 may be used, a sample in which a part of the heat transfer member 11 is exposed from the surface of the sealing member 9 By using the configuration of 6 (Embodiment 1), the surface of the sealing member 9 is sufficiently warmed, and the moisture permeability of the sealing member 9 is improved. For this reason, it can be said that the sample 6 is more preferable than the sample 7 from the viewpoint of suppressing bubbles.

  In the present embodiment, in particular, in a sealing member 9 when a large-sized power semiconductor device having a plurality of (for example, eight) substrates 3 is driven in one case 1 as shown in the fifth embodiment. Investigating thermal diffusion and creeping insulation resistance. First, the sample used for the investigation of this example will be described with reference to FIGS.

  Referring to FIGS. 11A to 11D, this corresponds to a sample 11 of the power semiconductor device for investigation. 11A to 11D have basically the same configuration as the power semiconductor device of the fifth embodiment shown in FIGS. 8A to 8D, but have a heat transfer member 11. FIG. 11 differs from FIG. 8 in that there is no point. In this sense, the sample 11 in FIG. 11 is a sample for comparison with the fifth embodiment. Other than this, the configuration of the sample 11 (comparative example) in FIGS. 11A to 11D is almost the same as the configuration of the fifth embodiment in FIGS. The same reference numerals are given and description thereof will not be repeated.

  Referring to FIGS. 12A to 12D, this corresponds to the sample 12 of the power semiconductor device for investigation. 12A to 12D have basically the same configuration as the power semiconductor device of the fifth embodiment shown in FIGS. 8A to 8D, and the embodiment is similar to FIG. A plurality of small heat transfer members 11 similar to 4 are arranged.

  Referring to FIGS. 13A to 13D, this corresponds to the sample 13 of the power semiconductor device for investigation. 13A to 13D, a plurality of heat transfer members 11 are arranged, but their shapes and modes are different from those in FIG. 12 (sample 12: Embodiment 5).

  In order to explain this, particularly in FIGS. 11A and 13A, the shortest distance from any of the source electrode 7a, the drain electrode 7b, and the gate electrode 7c of the electrode member 7 exceeds 25 mm. Is shown as region 51.

  The heat transfer member 11 of the sample 13 is connected to a part of any one of the electrode members 7 (the source electrode 7a or the drain electrode 7b) so that both are integrated, and from there, the region 51 described above is formed. To extend along the main surface of the substrate 3. The heat transfer member 11 spreads on both the left and right sides in the X direction (up and down sides in the Y direction), for example, so that the entire region 51 has the flat layer 11a in the same manner as the flat layer 11a in the first embodiment. Yes. As a result, a region in which the shortest distance between any one of the heat transfer member 11 and the plurality of electrode members 7 of the sample 13 exceeds 25 mm does not always exist in the sample 13.

  That is, the region 51 is originally a region where the shortest distance exceeds 25 mm when viewed from any electrode member 7. However, by arranging the heat transfer member 11 connected to and extending from the electrode member 7 in this region 51, the heat transfer member 11 can be seen to have the same function as the electrode member 7 (as the electrode member 7). Therefore, the distance from the electrode member 7 (as the heat transfer member 11) is also 25 mm or less in the region 51. Thereby, similarly to the other areas, the distance from any one of the electrode members 7 is 25 mm or less in the area 51 as well.

  The planar layer 11a is attached for the purpose of electrical conduction, and is continuous with the source electrode 7a and the like, and therefore, the planar layer 11a is also energized. However, there is no electrical conduction from the heat transfer member 11 including the flat layer 11a to the outside of the power semiconductor device.

  Since the materials of the various members constituting these samples, the method of manufacturing each sample, and the method of reliability testing are the same as those in Example 1, the description thereof will not be repeated. Referring to FIG. 11A again, the temperature of the sealing member 9 is the top surface of the sealing member at three points A, B, and C shown in FIG. The temperature of 9a was measured using a thermocouple.

  Table 3 below shows the results obtained by conducting the same investigation as Samples 1 to 10 on Samples 11 to 13.

  Referring to Table 3, in the power semiconductor device of Sample 11 corresponding to the comparative example (FIG. 11), the temperature at point B was 45 ° C., and the temperature difference from the chip was 130 ° C. Also, dielectric breakdown marks were confirmed when the power cycle test was performed for 60 k cycles.

  On the other hand, by providing the heat transfer member 11 as in samples 12 and 13, the temperature difference from the chip was reduced, and dielectric breakdown did not occur after a predetermined number of power cycles. Also in the present embodiment, the reliability of the power semiconductor device could be improved by installing the heat transfer member 11 based on the same theory as in the first and second embodiments.

  The region 51 is a region away from any of the electrode members 7 and is a region that tends to become the low temperature region 21 (see FIGS. 3 and 4) of the sealing member 9. Therefore, by providing the heat transfer member 11 extending from a part of the electrode member 7 to the region 51, the sealing member 9 in the region 51 can be warmed with high efficiency, and effects such as suppression of the generation of bubbles can be obtained. Can play.

  If the theory of the heat transfer member 11 of the sample 13 is applied, for example, the electrode member 7 itself can be extended to the region 51 and the electrode member 7 in the region 51 can be used as the heat transfer member 11. That is, the heat transfer member 11 in the region 51 can have both the function as the heat transfer member 11 and the function as the electrode member 7. In this way, it is not necessary to attach the heat transfer member 11 separately, and it is not necessary to secure a space for connecting the heat transfer member 11 on the surface of the substrate 3 (surface electrode 3c). For this reason, the heat transfer member 11 can be formed more easily. This method is particularly effective for a power semiconductor device in which many mounting components are arranged.

  In this case, the region 51 is defined as a region having a shortest distance exceeding 25 mm from any electrode member 7 (excluding the electrode member 7 used as the heat transfer member 11). In this sense, the portion extended from the electrode member 7 so as to function as the heat transfer member 11 (although the electrode member 7 and the heat transfer member 11 are integrated) is different from the electrode member 7 in other regions. It can also be considered a member.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 case, 3, 31, 32, 33, 34, 35, 36, 37, 38 substrate, 3a, 31a, 32a, 33a, 34a, 35a, 36a, 37a, 38a insulating substrate, 3b, 31b, 32b, 33b, 34b, 35b, 36b, 37b, 38b Back electrode, 3c, 31c, 32c, 33c, 34c, 35c, 36c, 37c, 38c Surface electrode, 5 Semiconductor element, 7 Electrode member, 7a Source electrode, 7a1, 7a2, 7a3 Source Terminal, 7b drain electrode, 7b1, 7b2, 7b3 source terminal, 7c gate electrode, 9 sealing member, 9a top surface of sealing member, 11 heat transfer member, 11a plane layer, 13 lid, 14 gap, 15 base plate, 17 Wire, 19 mounting screw holes, 21 low temperature region, 25 bubbles, Gs gas.

Claims (15)

A substrate placed in the case;
A semiconductor element mounted on one main surface of the substrate;
An electrode member connected to the substrate and electrically conductive with the outside of the semiconductor element;
A sealing member filling the case;
A semiconductor device comprising: a heat transfer member different from the electrode member connected to a part of the substrate or a part of the electrode member in the case.   The semiconductor device according to claim 1, wherein a base plate is connected to the other main surface of the substrate opposite to the one main surface.   The semiconductor device according to claim 2, wherein the material constituting the base plate is any one selected from the group consisting of copper, aluminum silicon carbide, and copper molybdenum.   The semiconductor device according to claim 1, wherein the sealing member is a silicone-based resin. A plurality of the electrode members;
5. The heat transfer member according to claim 1, wherein the heat transfer member is disposed at a position where the shortest distance from the electrode member of the plurality of electrode members is 25 mm or less. A semiconductor device according to 1. A plurality of the electrode members;
The heat transfer member is connected to a part of any one of the plurality of electrode members, and there is a region where the shortest distance between the heat transfer member and all of the plurality of electrode members exceeds 25 mm. The semiconductor device according to claim 1, wherein the semiconductor device is arranged so as not to occur.   The difference between the temperature of the surface during driving of the semiconductor element and the minimum value of the temperature of the surface on the same side as the one main surface of the sealing member is 120 ° C. or less. 2. A semiconductor device according to item 1.   The material constituting the semiconductor element is any one selected from the group consisting of silicon carbide, gallium nitride, diamond, and a composite material of silicon carbide, gallium nitride, and diamond. 2. The semiconductor device according to claim 1.   9. The semiconductor device according to claim 1, wherein the material constituting the heat transfer member is any one selected from the group consisting of aluminum, copper, and an alloy of aluminum and copper. .   The semiconductor device according to claim 1, wherein the heat transfer member extends in a direction intersecting with the one main surface.   The semiconductor device according to claim 1, wherein at least a part of the heat transfer member is exposed from a surface of the sealing member.   The semiconductor device according to claim 1, wherein the heat transfer member includes a planar layer that extends along a surface along the one main surface of the sealing member.   The semiconductor device according to claim 1, wherein the heat transfer member is a ribbon wire.   The semiconductor device according to claim 13, wherein the heat transfer member is formed of a carbon-based composite material.   15. The semiconductor according to claim 13, wherein the ribbon wire forms a loop between the ribbon wire and the substrate by being connected to two spaced apart locations on the one main surface of the substrate. apparatus.

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