JP2014096412A - Semiconductor module - Google Patents

Abstract

A semiconductor module 2 is provided which can improve cooling performance and can be miniaturized.
SOLUTION: The heat sink 4 and the heat sink 5 laminated in the plate thickness direction X, the IGBT 3 joined to the heat sink 4, the lead frame 11 joined to the IGBT 3, and the diode 6 joined to the heat sink 5. And a lead frame 13 joined to the diode 6, and the outer surface of the lead frame 11 in the plate thickness direction X has a cooling surface 11 a that can contact the cooling portion 17 that cools the lead frame 11. The outer surface of the lead frame 13 in the plate thickness direction X has a cooling surface 13a that can come into contact with the cooling unit 18 that cools the lead frame 13. Joined by TIG welding, the heat sinks 4, 5, IGBT 3, diode 6, and lead frames 11, 13 are sealed with a mold resin 19.
[Selection] Figure 2

Description

  The present invention relates to a semiconductor module that can be used as an inverter.

  For example, a semiconductor module used in a power conversion device that controls an electric device such as a motor includes a switching element (for example, IGBT) for controlling a current supplied to a load. Between the collector electrode and the emitter electrode of the switching element, a rectifying element (refluxing diode) that circulates the load current is connected to prevent breakdown of the element when a reverse voltage is applied (see, for example, Patent Documents 1 and 2). ).

  In the semiconductor module described in Patent Document 1, the IGBT chip and the reflux diode chip are arranged with the base plate interposed therebetween, and both surfaces of the base plate are arranged so that the collector electrode surface of the IGBT chip and the cathode surface of the reflux diode chip face each other. It is joined to. The IGBT chip and the reflux diode are fixed to the base plate with solder or the like.

  The emitter electrode of the IGBT chip is connected to the emitter electrode terminal via a bus bar which is a plate-like metal wiring. Similarly, the anode electrode of the freewheeling diode chip is connected to the emitter electrode terminal via a bus bar which is a plate-like metal wiring. The semiconductor module accommodates components such as an IGBT chip, a reflux diode chip, a base plate, and a bus bar in a case which is a casing, and these components are sealed with silicon gel.

  The semiconductor module described in Patent Document 2 includes a pair of substrates made of a material such as highly thermally conductive ceramics, and a switching element and a diode element are disposed between the pair of substrates. The switching element and the diode element are electrically connected to the substrate by solder or a high thermal conductive adhesive. Patent Document 2 discloses an inverter module having a structure in which two sets of semiconductor modules are arranged on both sides of a terminal plate. In this inverter module, the switching element and the diode element are arranged to face each other with the terminal plate interposed therebetween.

JP 2005-197340 A JP 2004-319562 A

  However, the conventional techniques described in Patent Documents 1 and 2 have insufficient cooling performance. Accordingly, it is an object of the present invention to provide a semiconductor module capable of improving the cooling performance and reducing the size.

  The present invention includes a first heat radiating plate and a second heat radiating plate laminated in a plate thickness direction, a switching element joined to a surface of the first heat radiating plate opposite to the second heat radiating plate, A first lead frame that is joined to a surface opposite to the first heat dissipation plate of the element to form a plate shape, and a rectifying element that is bonded to a surface opposite to the first heat dissipation plate of the second heat dissipation plate And a second lead frame that is joined to a surface opposite to the second heat dissipation plate of the rectifying element and forms a plate shape, and the outer surface in the plate thickness direction of the first lead frame is A cooling part that has a first cooling surface that can come into contact with a cooling part that cools the first lead frame, and an outer surface in the thickness direction of the second lead frame cools the second lead frame. The first and second lead frames have a plate thickness. Projecting in the first direction intersecting the direction, the ends of each are joined by TIG welding, the first heat radiating plate, the second heat radiating plate, the switching element, the rectifying element, the first lead frame, and the second A semiconductor module in which a lead frame is molded and sealed is provided.

  Since the semiconductor module includes the plate-like first lead frame that comes into contact with the switching element, the heat of the switching element can be transferred to the first lead frame. Since the semiconductor module includes the plate-like second lead frame that comes into contact with the rectifying element, the heat of the rectifying element can be transferred to the second lead frame.

  Since the first cooling surface is formed on the outer surface in the plate thickness direction of the first lead frame and the second cooling surface is formed on the outer surface in the plate thickness direction of the second lead frame, the plate The first lead frame and the second lead frame can be cooled from both sides in the thickness direction. Accordingly, the switching element and the rectifying element can be suitably cooled via the first lead frame and the second lead frame, and cooling can be performed with a simple configuration. The semiconductor module can be miniaturized.

  In the semiconductor module, the first lead frame and the second lead frame are bent inward in the plate thickness direction outside the first direction and approach each other, and the ends are joined at the center in the plate thickness direction. The structure which is may be sufficient. According to the semiconductor module having this configuration, since the end portion of the first lead frame and the end portion of the second lead frame are close to each other in the center in the plate thickness direction, it is easy to perform TIG welding and has a simple configuration. It can be.

  The semiconductor module is in surface contact with the first cooling surface to cool the first lead frame, and the second cooling surface is in surface contact with the second cooling surface to cool the second lead frame. A first heat radiating plate, a second heat radiating plate, a switching element, a rectifying element, a first lead frame, and a second lead frame, the first cooling portion and the second cooling portion. A structure in which the mold is sealed may be used. According to the semiconductor module having this configuration, the first lead frame and the second lead frame can be cooled by being sandwiched from both sides in the plate thickness direction by the first cooling unit and the second cooling unit, respectively. In addition, the first heat sink, the second heat sink, the switching element, the rectifier, the first lead frame, and the second lead frame are mold-sealed between the first cooling section and the second cooling section. Therefore, the first heat radiating plate, the second heat radiating plate, the switching element, the rectifying element, the first lead frame, and the second lead frame can be suitably protected.

  The first heat radiating plate and the second heat radiating plate may be stacked in the plate thickness direction by folding a single substrate. According to this configuration, a single substrate is prepared, the switching element and the rectifying element are bonded to the same surface, and the substrate to which the switching element and the rectifying element are bonded is folded, whereby the first heat radiation plate and the second heat sink Can be laminated in the thickness direction.

  A switching element and a rectifying element may be disposed on the same surface of a single substrate, and a notch may be formed between the switching element and the rectifying element. Accordingly, the substrate can be easily folded back with the notch as a boundary.

  ADVANTAGE OF THE INVENTION According to this invention, while aiming at the improvement of cooling performance, the semiconductor module which can achieve size reduction can be provided.

It is a perspective view showing a semiconductor device provided with a semiconductor module concerning one embodiment of the present invention. It is sectional drawing which shows the semiconductor module in FIG. 1, and is sectional drawing which follows the II-II line. It is sectional drawing which shows the semiconductor module in FIG. 1, and is sectional drawing which follows an III-III line. It is an equivalent circuit diagram of the semiconductor module according to the present embodiment. It is the figure which showed the manufacturing procedure of the semiconductor module which concerns on this Embodiment. It is the figure which showed an example of the semiconductor module.

  Hereinafter, preferred embodiments of a semiconductor module according to the present invention will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a perspective view showing a semiconductor device including a semiconductor module according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the semiconductor module in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is an equivalent circuit diagram of the semiconductor module according to the present embodiment.

  The semiconductor device 1 shown in FIG. 1 can be applied to an inverter of a motor system mounted on a vehicle (for example, a hybrid vehicle or an electric vehicle) having, for example, a three-phase AC motor as a drive source. The semiconductor device 1 includes a plurality of semiconductor modules 2. In the semiconductor module 2 according to the present embodiment, an IGBT 3 is used as a switching element (power element).

  As shown in FIG. 2, the semiconductor module 2 includes a pair of heat sinks 4 and 5 stacked in the plate thickness direction X. The IGBT 3 and the diode 6 (rectifier element) are sandwiched between the pair of heat sinks 4 and 5. ) And are arranged back to back. The phrase “the IGBT 3 and the diode 6 are arranged back to back” means that the current flowing through the IGBT 3 and the current flowing through the diode 6 are arranged in opposite directions. In FIG. 2, one semiconductor module 2 is illustrated.

  The IGBT 3 is disposed on the surface side of the heat radiating plate 4 (the surface opposite to the heat radiating plate 5). A predetermined insulating substrate circuit 7 is formed on the surface of the heat sink 4. The collector electrode (current input) surface of the IGBT 3 is disposed on the heat sink 4 side. The IGBT 3 is electrically connected to the insulating substrate circuit 7 formed on the heat radiating plate 4 by being joined by solder 8. The insulating substrate circuit 7 is a circuit made of, for example, a ceramic substrate (DBA).

  A diode 6 is disposed on the surface side of the heat radiating plate 5 (surface opposite to the heat radiating plate 4). A predetermined insulating substrate circuit 9 is formed on the surface of the heat sink 5. The cathode electrode surface of the diode 6 is disposed on the heat radiating plate 5 side. The diode 6 is electrically connected to the insulating substrate circuit 9 formed on the heat radiating plate 5 by being joined by solder 10. The insulating substrate circuit 9 is a circuit made of, for example, a ceramic substrate (DBA).

  The diode 6 is connected between the collector electrode 3C and the emitter electrode 3E (see FIG. 4) of the IGBT 3 and functions as a free-wheeling diode that bypasses the negative overcurrent in order to prevent breakage during reverse voltage application. The cathode electrode of the diode 6 is connected to the collector electrode 3C of the IGBT 3. The anode electrode of the diode 6 is connected to the emitter electrode 3E of the IGBT 3.

  For example, cooling fins (not shown) are formed on the radiator plates 4 and 5. The heat radiating plates 4 and 5 are provided with cooling fins in a portion protruding outward from a portion sealed with a mold resin 19 described later. The cooling fins are cooled by the cooling water and cool the radiator plates 4 and 5.

  A plate-like lead frame 11 (first lead frame) is disposed on the surface of the IGBT 3 (the surface opposite to the heat radiating plate 4). The lead frame 11 is joined to the surface of the IGBT 3 by solder 12. The IGBT 3 and the lead frame 11 are electrically connected via solder 12. For example, the lead frame 11 is disposed so as to cover the entire outer surface of the IGBT 3 in the plate thickness direction X. Heat generated in the IGBT 3 is transferred to the heat radiating plate 4 and the lead frame 11.

  A plate-like lead frame 13 (second lead frame) is disposed on the surface of the diode 6 (surface opposite to the heat sink 5). The lead frame 13 is joined to the surface of the diode 6 by solder 14. The diode 6 and the lead frame 13 are electrically connected via the solder 14. For example, the lead frame 13 is disposed so as to cover the entire outer surface of the diode 6 in the plate thickness direction X. Heat generated by the diode 6 is transferred to the heat radiating plate 5 and the lead frame 13.

  As the material of the lead frames 11 and 13, a metal material having high electrical conductivity and high thermal conductivity, such as copper (Cu), aluminum (Al), copper molybdenum (MoCu), or the like can be considered. The lead frames 11 and 13 preferably have high heat dissipation performance.

  The lead frames 11 and 13 project in a first direction Z (vertical direction in FIG. 2) intersecting the plate thickness direction X. The lead frames 11 and 13 extend outward (upward in the drawing) from the heat sinks 4 and 5, the IGBT 3, and the diode 6 in the Z direction. A junction terminal 15 is formed on the outer end of the lead frame 11 in the Z direction. A junction terminal 16 is formed at the outer end of the lead frame 13 in the Z direction.

  The lead frames 11 and 13 are bent inward in the plate thickness direction X at positions outside the heat sinks 4 and 5 in the Z direction. The joining terminals 15 of the lead frame 11 and the joining terminals 16 of the lead frame 13 are in contact with each other at the center in the plate thickness direction X. The joining terminals 15 and 16 are joined by TIG welding. The emitter wiring that connects the emitter electrode 3E and the diode 6 and the collector wiring that connects the collector electrode 3C and the diode 6 are connected by lead frames 11 and 13, respectively.

  In TIG welding (tungsten-inert-gas arc welding), an arc is generated between the tungsten electrode and the workpieces (joining terminals 15 and 16) in an atmosphere of an inert gas such as argon or helium, and the heat is generated. Weld using.

  A cooling unit 17 (first cooling unit) that cools the lead frame 11 is disposed outside the lead frame 11 in the plate thickness direction X. The cooling unit 17 is formed in a plate shape, for example, and is arranged so that the thickness direction of the cooling unit 17 is along the X direction. On the outer surface of the lead frame 11 in the plate thickness direction X, a cooling surface 11a (heat transfer surface) that is cooled in contact with the cooling unit 17 is formed.

  A cooling unit 18 (second cooling unit) that cools the lead frame 13 is disposed outside the lead frame 13 in the plate thickness direction X. The cooling unit 18 is formed in a plate shape, for example, and is arranged so that the thickness direction of the cooling unit 18 is along the X direction. On the outer surface of the lead frame 13 in the plate thickness direction X, a cooling surface 13a (heat transfer surface) that is cooled in contact with the cooling unit 18 is formed.

  Inside the cooling units 17 and 18, a conduit through which the refrigerant flows and cooling fins are formed. By flowing the refrigerant into the cooling units 17 and 18, the heat transmitted to the cooling units 17 and 18 is transmitted to the refrigerant and released outside the cooling units 17 and 18. The cooling units 17 and 18 (coolers) are arranged so as to sandwich the lead frames 11 and 13 from both sides in the plate thickness direction X, and cool the lead frames 11 and 13.

  Each component (heat sinks 4 and 5, insulating substrate circuits 7 and 9, IGBT 3, diode 6, lead frame 11 and 13, solder frame 8, 10, 12, and 14) disposed between the pair of cooling units 17 and 18 is as follows. Sealed with a mold resin 19. The lead frames 11 and 13 are sealed with a mold resin 19 except for the cooling surfaces 11a and 13a that contact the cooling portions 17 and 18. In this way, the above-described components are protected by sealing with the mold resin 19. The solders 8, 10, 12, and 14 are protected by the mold resin 19, and the reliability as solder is improved.

  As shown in FIG. 1, the semiconductor device 1 includes a plurality of semiconductor modules 2 in the plate thickness direction X. In the semiconductor device 1, cooling parts (17, 18) are arranged on both sides of the semiconductor module 2. The semiconductor device 1 may have a configuration in which a plurality of semiconductor modules 2 are provided in the Y direction, which is a direction intersecting the X direction and the Z direction. The semiconductor device 1 includes a connection terminal 22 adjacent to the IGBT 3 and the diode 6 in the Y direction.

  3 is a cross-sectional view taken along line III-III in FIG. In the semiconductor device 1, the cooling units 17 and 18 and the heat radiating plates 4 and 5 extend in the Y direction. As described above, the insulating substrate circuits 7 and 9 are formed on the heat sinks 4 and 5.

  A lead frame 24 having a plate shape is disposed on the upper surface of the insulating substrate circuit 7 (surface opposite to the heat radiating plate 4). Similarly, a lead frame 25 having a plate shape is disposed on the upper surface of the insulating substrate circuit 9 (surface opposite to the heat sink 5). The lead frames 24 and 25 project in a first direction Z (vertical direction in FIG. 3) intersecting the plate thickness direction X.

  The lead frames 24 and 25 are bent inward in the plate thickness direction X at positions outside the heat sinks 4 and 5 in the Z direction. The lead frames 24 and 25 are bent at the center in the plate thickness direction X to a distance that sandwiches the insulating substrate 23 extending in the Z direction between the lead frame 24 and the lead frame 25. The lead frames 24 and 25 bent to a distance sandwiching the insulating substrate 23 project in the Z direction and are connected to the connection terminal 22 above the portion sealed by the mold resin 19.

  The connection terminal 22 is provided for each semiconductor module 2 (see FIG. 1). The insulating substrate 23 extends in the Z direction so as to be sandwiched between the lead frame 24 and the lead frame 25. Each component disposed between the pair of cooling units 17 and 18 is sealed with a mold resin 19.

  FIG. 4 shows an equivalent circuit diagram of the semiconductor module 2. A plurality of semiconductor modules 2 are connected to the semiconductor device 1. In the semiconductor device 1, an upper phase IGBT 3A (3) and a lower phase IGBT 3B (3) are connected in series between a positive electrode P and a negative electrode N on the circuit, and a capacitor 20 (snubber capacitor) is connected to the series connection. ) Are connected in parallel.

  An output side of an arbitrary phase (U phase or V phase or W phase) of the three-phase AC motor is connected to a connection point 21 between the emitter electrode 3E of the upper phase IGBT 3 and the collector electrode 3C of the lower phase IGBT 3. A gate terminal is connected to the gate electrode 3G of the IGBT 3.

  The snubber capacitor 20 is a capacitor for suppressing a surge voltage in the semiconductor module 2. As the snubber capacitor 20, a ceramic capacitor, a film capacitor, or the like is applied. Two or more snubber capacitors 20 may be provided in series. Note that the number of snubber capacitors may be one, or three or more.

  Next, manufacturing of the semiconductor module 2 described above will be described with reference to FIG. FIG. 5 is a diagram showing a manufacturing procedure of the semiconductor module according to the present embodiment. FIG. 5 does not show the above-described insulating substrate circuits 7 and 9. As shown in FIG. 5A, the semiconductor module 2 is first solder-bonded in a state where the radiator plates 4 and 5 are a single flat substrate. That is, the IGBT 3 is joined to the heat sink 4 by the solder 8, and the lead frame 11 is joined to the IGBT 3 by the solder 12. Further, the diode 6 is joined to the heat sink 5 by the solder 10, and the lead frame 13 is joined to the diode 6 by the solder 14. After the solder joint, bending is performed so as to be folded back at the notch 31 between the IGBT 3 and the diode 6 (the connection point between the heat sink 4 and the heat sink 5).

  After the bending process described above, as shown in FIG. 5B, TIG welding of the joining terminals 15 and 16 is performed in a state where the surfaces of the joining terminals 15 and 16 are in contact with each other. Finally, the heat sinks 4 and 5, the IGBT 3, the diode 6, the lead frames 11 and 13, and the solders 8, 10, 12, and 14 are sealed with a mold resin 19.

  Next, effects of the semiconductor module 2 according to the present embodiment will be described. Since the semiconductor module 2 includes the lead frame 11 that contacts the IGBT 3 and the lead frame 13 that contacts the diode 6, the heat of the IGBT 3 is supplied to the lead frame 11, and the heat of the diode 6 is supplied to the lead frame 13, respectively. Heat can be transferred. Since the first cooling surface is formed on the outer surface of the lead frame 11 and the second cooling surface is formed on the outer surface of the lead frame 13, the upper surface of the element is interposed via the lead frames 11 and 13, respectively. Thus, the IGBT 3 and the diode 6 can be suitably cooled. Since the IGBT 3 and the diode 6 can be suitably cooled with a simple configuration, the IGBT 3 and the diode 6 can be downsized, and the semiconductor module 2 can be downsized.

  In addition, since both IGBT3 and the diode 6 can be cooled also with the heat sinks 4 and 5 arrange | positioned in the center of the semiconductor module 2, more effective cooling is attained. Further, as shown in FIG. 2, the IGBT 3 and the diode 6 are arranged back to back via the heat sinks 4 and 5, so that the currents flowing in the IGBT 3 and the diode 6 flow in opposite directions, and the current flows. Magnetic fields generated by flowing will cancel each other. As a result, the inductance is reduced and the surge voltage can be reduced. In the semiconductor module 2, since the generation of surge voltage can be reduced, the switching speed of the IGBT 3 can be increased and the switching loss can be reduced.

  In the semiconductor module 2, the lead frame 11 and the lead frame 13 are bent inward in the plate thickness direction X on the outer side in the Z direction and approach each other, and the end portions are joined at the center in the plate thickness direction X. Therefore, it is easy to perform TIG welding, and a simple configuration can be achieved.

  Further, the semiconductor module 2 includes the cooling units 17 and 18, and the heat sinks 4 and 5, the IGBT 3, the diode 6, and the lead frames 11 and 13 are molded and sealed between the cooling unit 17 and the cooling unit 18. Thus, the lead frames 11 and 13 can be cooled by the cooling unit 17 and the cooling unit 18 so as to be sandwiched from both sides in the plate thickness direction X, respectively. Moreover, since the heat sinks 4 and 5, IGBT 3, diode 6, and lead frames 11 and 13 can be molded and sealed between the cooling part 17 and the cooling part 18, the heat sinks 4 and 5, IGBT 3, diode 6, lead frame 11, 13 can be suitably protected.

  Further, the heat sink 4 and the heat sink 5 are configured such that one board is folded and overlapped in the plate thickness direction X, so that the IGBT 3 and the diode 6 can be connected in a single board state (planar state). It is possible to stack the heat sinks 4 and 5 in the plate thickness direction X by folding the substrates to which the elements are bonded. This facilitates the manufacture of the semiconductor module 2.

  Further, the IGBT 3 and the diode 6 may be disposed on the same plane of the single substrate described above, and the notch 31 may be formed between the IGBT 3 and the diode 6. Thus, the substrate can be easily folded back with the notch 31 as a boundary, and the manufacture of the semiconductor module 2 becomes easier.

  As mentioned above, although preferred embodiment of the semiconductor module of this invention was described, the semiconductor module of this invention is not limited to embodiment mentioned above. For example, the semiconductor module shown in FIG. 6 may be used. FIG. 6 shows only the portions necessary for explanation. In the semiconductor module 2A shown in FIG. 6, two IGBTs 3A and 3A are installed side by side in the Y direction. The IGBTs 3A and 3A installed side by side are connected in parallel and connected by a common lead frame 11A. When the elements are connected in parallel as in the semiconductor module 2A, the elements may be connected by a common lead frame 11A. When IGBTs 3A and 3A are connected in parallel by wire bonding, a phenomenon (current imbalance) that current concentrates on one IGBT 3A may occur. By connecting, occurrence of current imbalance can be suppressed.

  Moreover, in the said embodiment, although IGBT3 was illustrated as a switching element and the diode 6 was illustrated as a rectifier, it was not limited to this, A various switching element and a rectifier can be used. .

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor device, 2 ... Semiconductor module, 3 ... IGBT (switching element), 4 ... Heat sink (1st heat sink), 5 ... Heat sink (2nd heat sink), 6 ... Diode (rectifier element), DESCRIPTION OF SYMBOLS 11 ... Lead frame (1st lead frame), 11a ... Cooling surface (1st cooling surface), 13 ... Lead frame (2nd lead frame), 13a ... Cooling surface (3rd cooling surface), 17 ... Cooling part (first cooling part), 18 ... cooling part (second cooling part), 19 ... mold resin, 31 ... notch.

Claims (5)

A first heat radiating plate and a second heat radiating plate laminated in the plate thickness direction;
A switching element joined to a surface of the first heat radiating plate opposite to the second heat radiating plate;
A first lead frame which is joined to a surface of the switching element opposite to the first heat dissipating plate to form a plate;
A rectifying element joined to a surface of the second heat sink opposite to the first heat sink;
A second lead frame that is joined to a surface of the rectifying element opposite to the second heat dissipating plate to form a plate,
The outer surface in the plate thickness direction of the first lead frame has a first cooling surface that can come into contact with a cooling unit that cools the first lead frame,
The outer surface in the plate thickness direction of the second lead frame has a second cooling surface that can come into contact with a cooling unit that cools the second lead frame,
The first lead frame and the second lead frame are projected in a first direction intersecting the plate thickness direction, and ends of each other are joined by TIG welding,
A semiconductor module in which the first heat radiating plate, the second heat radiating plate, the switching element, the rectifying element, the first lead frame, and the second lead frame are molded and sealed.   The first lead frame and the second lead frame are bent inward in the plate thickness direction on the outside in the first direction and approach each other, and the end portions are joined in the center in the plate thickness direction. The semiconductor module according to claim 1. A first cooling section that is in surface contact with the first cooling surface and cools the first lead frame;
A second cooling unit that is in surface contact with the second cooling surface and cools the second lead frame;
The first heat radiating plate, the second heat radiating plate, the switching element, the rectifying element, the first lead frame, and the second lead frame include the first cooling unit and the second cooling frame. The semiconductor module according to claim 1, which is mold-sealed between the parts.   4. The semiconductor module according to claim 1, wherein the first heat radiating plate and the second heat radiating plate are stacked in the plate thickness direction by folding a single substrate. 5. The semiconductor according to claim 4, wherein the switching element and the rectifying element are arranged on the same surface of the single substrate, and a notch is formed between the switching element and the rectifying element. module.

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