JP2014049582A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive, highly reliable, and highly productive semiconductor device capable of achieving high heat dissipation.SOLUTION: A semiconductor device comprises: a circuit pattern 15 fixed to a metallic base plate 17 via an insulating layer 16; a semiconductor element bonded to the circuit pattern 15; a plurality of cylindrical sockets 11, one end of each of the cylindrical sockets being bonded to the circuit pattern 15; a sealing body for sealing the circuit pattern 15, the plurality of cylindrical sockets 11, and the semiconductor element; and an external electrode connection terminal 21 in which an attaching portion 29 to an external electrode is linked to a body portion 27 provided with a plurality of insertion portions 26 inserted into the cylindrical socket 11. The attaching portion 29 and the body portion 27 are produced by bending a flat plate.

Description

  The present invention relates to a semiconductor device, and more particularly to a semiconductor device in which a semiconductor element is sealed with a sealing material such as a mold resin.

  Mold resin, potting resin, and the like are used to seal power semiconductor devices. In the sealed power semiconductor device, a method of taking out the external electrode becomes a problem. For example, the invention relating to Patent Document 1 solders a copper cylinder (cylindrical socket) as an external electrode lead-out portion to the surface of a ceramic substrate. Then, the semiconductor substrate for electric power is formed by carrying out transfer molding of the ceramic substrate using an epoxy resin. The output terminal is taken out from the upper surface of the semiconductor device using a metal external electrode.

  In power semiconductor devices, instantaneous heat generation is large due to a large energization current. In order to suppress the temperature rise, a plurality of copper cylinders are used in consideration of the heat capacity. However, because the copper cylinder is displaced during soldering, the pitch intervals of the plurality of copper cylinders are slightly different. It is desired that the external electrode connection terminal can absorb the displacement of the copper cylinder.

JP 2007-184315 A

  The present invention has been made to solve the above-described problems. In addition to realizing high heat dissipation, an object of the present invention is to obtain a semiconductor device that is inexpensive, highly reliable, and highly productive. Yes.

  A semiconductor device according to the present application includes a circuit pattern fixed to a metal base plate via an insulating layer, a semiconductor element bonded to the circuit pattern, a plurality of cylindrical sockets bonded at one end to the circuit pattern, and a circuit An external electrode connection in which a mounting portion to an external electrode is connected to a body portion provided with a plurality of insertion portions to be inserted into the cylindrical socket, a sealing body for sealing a pattern, a plurality of cylindrical sockets and semiconductor elements Terminal. The attachment portion and the body portion are formed by bending a flat plate.

  Even if the displacement of the cylindrical socket becomes large, the insertion portion can obtain a normal contact, so that the reliability is high. In addition, an increase in temperature can be suppressed because the external terminal has a sufficient heat capacity against instantaneous heat generation.

It is front sectional drawing which shows the whole structure of a semiconductor device. It is sectional drawing which shows the relationship between a cylindrical socket and the terminal for external electrode connection. 2 is a side view of an external electrode connection terminal according to Embodiment 1. FIG. It is a top view which shows a semiconductor device. 6 is a front view of an external electrode connection terminal according to Embodiment 2. FIG. 6 is a front view of an external electrode connection terminal according to Embodiment 3. FIG. 6 is a front view of an external electrode connection terminal according to Embodiment 4. FIG. FIG. 10 is a perspective view of an external electrode connection terminal according to the fifth embodiment. 10 is a front view of an external electrode connection terminal according to Embodiment 5. FIG. FIG. 10 is a side view of an external electrode connection terminal according to the fifth embodiment. FIG. 10 is a front view of an external electrode connection terminal according to a sixth embodiment. FIG. 10 is a cross-sectional view illustrating an insertion portion of an external electrode connection terminal according to a sixth embodiment. FIG. 20 is a front view of an external electrode connection terminal according to the seventh embodiment. FIG. 10 is a cross-sectional view illustrating an insertion portion of an external electrode connection terminal according to a seventh embodiment.

  Embodiments of a semiconductor device according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing the overall configuration of the semiconductor device. The circuit board 19 includes a copper base plate 17, an insulating layer 16 using a high thermal conductive resin, and a circuit pattern 15. One side of the base plate 17 is exposed from the mold resin 18. On the circuit pattern 15, a cylindrical socket 11, an IGBT (Insulated Gate Bipolar Transistor) 12, and an FWDi (Free-Wheeling Diode) 13 are joined by solder 14. An external electrode connection terminal 21 is press-fitted into the cylindrical socket 11. The external electrode connection terminal 21 made of a copper-based material is provided with a mounting hole 22.

  In the semiconductor device 1, power semiconductor elements such as IGBT 12 and FWDi 13 are sealed with a mold resin 18. In addition to mold resin, potting resin, gel, etc. are used as the sealing material. As the power semiconductor element, in addition to those formed of silicon (Si), those formed of a wide band gap semiconductor having a band gap larger than that of silicon can be suitably used. Examples of the wide band gap semiconductor include silicon carbide (SiC), a gallium nitride material, and diamond. When a wide bandgap semiconductor is used, the allowable current density is high and the power loss is low, so that a device using the power semiconductor element can be downsized.

  The cylindrical socket 11 can be made of a metal other than copper or another conductive material. The entirety of the semiconductor device 1 is transfer-molded with a mold resin 18, and insulation from the outside is maintained. Since the mold resin 18 firmly adheres and fixes the surfaces of the circuit board 19, IGBT 12 and FWDi 13 having different linear expansion coefficients, thermal fatigue due to temperature rise during use can be suppressed. The power semiconductor device sealed with the mold resin has higher reliability than the gel type power semiconductor device.

  FIG. 2 is a cross-sectional view of the semiconductor device viewed from a direction perpendicular to FIG. 1 and shows a state in which the external electrode connection terminal 21 is inserted into the cylindrical socket 11. FIG. 3 is a side view showing the configuration of the external electrode connection terminal. The external electrode connection terminal 21 includes an insertion portion 26, a body portion 27, and an attachment portion 29. The attachment portion 29 and the plurality of insertion portions 26 are connected by a body portion 27. The insertion portion 26 is formed with an opening 28 and has a needle eye shape. The needle eye shape is generally called a press fit. Two insertion parts 26 are provided in the body part 27 at intervals. The attachment portion 29 is bent 90 degrees from the body portion 27. The insertion portion 26 of the external electrode connection terminal 21 is inserted into the cylindrical socket 11. Since the external electrode connection terminal 21 having the insertion portion 26 is used to attach to the external electrode from the upper surface of the semiconductor device, the output can be easily taken out. When the insertion portion 26 of the external electrode connection terminal 21 is press-fitted inside the cylindrical socket 11, due to the elastic deformation of the insertion portion 26, a repulsive force acts on the inner wall of the cylindrical socket 11 to ensure conduction.

  FIG. 4 is a top view showing the semiconductor device 1. In the figure, four external electrode connection terminals 21, four external electrodes 30, and eight cylindrical sockets 11 are shown. The external electrode connection terminal 21 is connected to an external electrode 30 in which a female screw is processed. The attachment hole 22 of the external electrode connection terminal 21 is formed in the attachment portion 29 of the external electrode connection terminal 21. The attachment hole 22 is formed to connect to the external electrode 30. A screw 31 is used to fix the external electrode 30 and the external electrode connection terminal 21. The copper external electrode connection terminal 21 is subjected to Ni base plating and Sn surface plating. This is for suppressing the surface oxidation of the external electrode connection terminal 21 and suppressing an increase in contact resistance due to the oxide film.

  The circuit pattern 15 of the circuit board 19 and the cylindrical socket 11 are joined by solder as described above. A process in the case of using a solder paste having viscosity at the time of soldering will be described. A solder paste is printed at a predetermined position of the circuit pattern 15, and a member (IGBT, FWDi, cylindrical socket) is mounted on the printed solder paste. The circuit board 19 is put into a reflow furnace and heated to the melting point of the solder or higher. The solder melts and wets the circuit pattern and predetermined portions of the member. Thereafter, cooling is performed, and joining of the member and the circuit pattern by soldering is completed.

  In this soldering process, the cylindrical socket is displaced. First, it occurs when the solder gets wet into the cylindrical socket. When the solder gets wet with the circuit pattern and the cylindrical socket, the surface tension acts on the cylindrical socket 11, and the cylindrical socket 11 is displaced. Furthermore, during the transfer of the sample in the reflow furnace, the cylindrical socket is displaced due to vibration. Due to these two factors, the cylindrical socket is displaced from the initial mounting position by a few hundred μm when it is large. Since the external electrode connection terminal 21 has a repulsive force acting on the inner wall of the cylindrical socket 11 due to the elastic deformation of the insertion portion 26, the external electrode connection terminal 21 ensures electrical continuity even if there is a positional shift of several hundred μm.

  Compare with other connection methods for semiconductor devices. For example, consider a method of using a socket in which a screw hole is formed instead of a cylindrical socket and fixing with a screw. The processing for forming the screw holes is complicated and expensive. In the present invention, by using the insertion portion, the oxide film on the inner wall of the cylindrical socket 11 can be removed and an ideal connection with low contact resistance can be obtained simply by inserting the external electrode connection terminal 21. Since the external electrode connection terminal 21 is processed by punching a flat plate by, for example, a progressive press, the insertion portion 26, the body portion 27, and the attachment portion 29 have the same thickness. Progressive press is a process in which a part of the material is connected in a single mold, and processes including punching, bending, molding, drawing, forging, and the like are performed with a single mold.

  The present invention has a particularly remarkable effect in a power semiconductor device such as a SiC module that operates at a high temperature. Since the electrode connection portion is at a high temperature, solder connection reliability is required for the electrode connection portion. Further, due to the downsizing of the module, the current flowing through the electrode terminal is a large current, and similarly, solder connection reliability is required. By adopting the external electrode connection terminal according to the present invention for the electrode connection that is generally soldered, the semiconductor can be operated at a temperature higher than the melting point of the solder. Furthermore, the insertion portion according to the present invention has a smaller electrode connection area than soldering. Since the thermal resistance between the insertion portion and the cylindrical socket is increased, heat conduction from the semiconductor to the external substrate can be suppressed. That is, the heat of the semiconductor is not easily transmitted to the substrate side. Even when the temperature of the semiconductor becomes high, the temperature rise of the substrate is suppressed, and the reliability of the substrate is increased.

Embodiment 2. FIG.
Next, the structure of the external electrode connection terminal 21 according to the second embodiment will be described in detail with reference to FIG. Note that the structure of the semiconductor device 1 is omitted since it is substantially the same as that described in the first embodiment. The body portion 27 has an insertion side end surface 27a, a side side end surface 27b, and a bending side end surface 27c. The slit 23 is formed in the middle part of the body part 27. When the insertion portion 26 of the external electrode connection terminal 21 is press-fitted into the cylindrical socket 11, if the insertion portion 26 is plastically deformed due to a large displacement of the cylindrical socket, a predetermined repulsive force cannot be obtained. However, by forming the slit 23 in the external electrode connection terminal 21, the body portion 27 continuous with the two insertion portions 26 of the external electrode connection terminal 21 can be independently deformed through the slit 23.

  According to the external electrode connection terminal according to the second embodiment, the body portion 27 is deformed so as to follow the cylindrical socket 11 that is displaced when the insertion portion 26 is press-fitted, so that plastic deformation of the insertion portion 26 can be prevented. Since a predetermined repulsive force from the inner wall of the cylindrical socket 11 is obtained, the contact resistance between the insertion portion 26 and the cylindrical socket 11 is sufficiently low. When the semiconductor device is used, the heat generation at the contact portion due to energization is sufficiently small, and it is possible to suppress the temperature rise of the semiconductor device below a predesigned temperature.

  In order to effectively dissipate heat generated by the power semiconductor elements, circuit patterns, and other members, heat capacity is required. Since the semiconductor device according to the present invention supplies a very large current of 150 A or more, a sufficient heat capacity is required even for the external electrode connection terminal. Heat generated at the contact portion between the insertion portion and the cylindrical socket is radiated to the circuit pattern side and the body portion side of the external electrode connection terminal. Since the portion where the slit is formed is a portion which hardly contributes to heat dissipation, the temperature rise hardly changes compared to the case where the slit is not formed.

Embodiment 3 FIG.
FIG. 6 shows an external electrode connection terminal 21 according to the third embodiment. The slit 23 is directed toward the bent side with the insertion side end face of the body portion 23 as a starting point 23a. By providing a recess (perforation) 24 at the base (end point) of the slit 23, when the two cylindrical sockets are displaced inward from each other, the recess 24 becomes a deformed portion and facilitates deformation of the body portion 27. The material for the external electrode connection terminal is preferably a copper-based material having an electrical resistivity close to that of oxygen-free copper. Moreover, in order for the insertion part 26 to work an appropriate repulsive force, it is preferable that it is a highly springy material with high rigidity. MZC1 (manufactured by Mitsubishi Shindoh Co., Ltd.) exists as a material that satisfies these characteristics. The slit starting point 23 a is disposed between the insertion portion 26 and the insertion portion 26.

Embodiment 4 FIG.
FIG. 7 shows an external electrode connection terminal 21 according to the fourth embodiment. A side end face 27b of the external electrode connection terminal 21 is cut out in a semicircular shape. By providing the recess 25 on the outer side of the body part 27, the body part 27 can be easily deformed even when the cylindrical sockets are displaced from each other. In FIG. 7, two recesses 25 are provided on both sides of the body portion 27.

Embodiment 5 FIG.
8 to 10 show the external electrode connection terminal 21 according to the fifth embodiment. The fifth embodiment is characterized in that the slit 23 formed in the external electrode connection terminal is provided up to the attachment portion 29. Further, in order to cope with a large current of 200 A or more, it is assumed that three insertion portions 26 are taken out from one external electrode connection terminal. According to the fifth embodiment, the external electrode connection terminal can be easily deformed even when the displacement of the cylindrical socket is increased. Furthermore, this structure is a structure that is resistant to external loads. That is, when the external electrode connection terminal 21 and the external electrode are fixed with screws, a torsional force is applied to the external electrode connection terminal. Due to the effect of the slit 23 extending beyond the body part to the attachment part, the body part 27 can be easily deformed even if the external electrode connection terminal receives a force in the rotational direction. A force in the rotational direction is not directly applied to the insertion portion 26, and a normal contact state can be maintained.

  The same effect as described above is also exhibited in a power cycle load and a temperature cycle load during energization. That is, the external electrode connection terminal is subjected to repeated load due to linear expansion mismatch between members due to temperature change. According to the present embodiment, since the body portion is deformed and a load is not repeatedly generated in the insertion portion, high reliability can be obtained over a long period of time. In the present embodiment, an example in which three insertion portions are provided in one external electrode connection terminal has been described, but the same effect is exhibited even when four or more insertion portions are formed.

Embodiment 6 FIG.
FIG. 11 is a front view showing the external electrode connection terminal 21 according to the sixth embodiment. 12 is a cross-sectional view taken along the line AA showing the insertion portion of the external electrode connection terminal 21 according to Embodiment 6 (see FIG. 11). The insertion portion 26 has a plurality of streaks or grooves extending in the longitudinal direction processed on the surface, and the cross-sectional shape of the insertion portion 26 has a star shape. The same effect of suppressing displacement as described above is exhibited.

Embodiment 7 FIG.
FIG. 13 is a front view showing the external electrode connection terminal 21 according to the sixth embodiment. FIG. 14 is a cross-sectional view taken along the line BB showing the insertion portion of the external electrode connection terminal 21 according to the seventh embodiment (see FIG. 13). The cross-sectional shape of the insertion portion 26 has a split pin type (or C shape). The same effect of suppressing displacement as described above is exhibited. The insertion unit 26 is created by bending a flat plate in the short direction.

  When SiC is used for the semiconductor element, the semiconductor device 1 is operated at a higher temperature than in the case of Si in order to take advantage of the characteristics. In a semiconductor device on which an SiC device is mounted, since higher reliability is required as a semiconductor device, the merit of the present invention for realizing a highly reliable semiconductor device becomes more effective.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  DESCRIPTION OF SYMBOLS 1 Semiconductor device, 11 Cylindrical socket, 12 IGBT, 13 FWDi, 14 Solder, 15 Circuit pattern, 16 Insulation layer, 17 Base board, 18 Mold resin, 19 Circuit board, 21 External electrode connection terminal, 22 Mounting hole, 23 Slit , 24 depression, 25 depression, 26 insertion part, 27 body part, 28 opening part, 29 attachment part

Claims (10)

A circuit pattern fixed via an insulating layer to a metal base plate;
A semiconductor element bonded to the circuit pattern;
A plurality of cylindrical sockets joined at one end to the circuit pattern;
A sealing body for sealing the circuit pattern, the plurality of cylindrical sockets, and the semiconductor element;
A semiconductor device comprising: a body portion provided with a plurality of insertion portions to be inserted into the cylindrical socket; and an external electrode connection terminal connected to an attachment portion to an external electrode.   The semiconductor device according to claim 1, wherein the attachment portion and the body portion of the external electrode connection terminal are formed by bending a flat plate.   The external electrode connection terminal is provided with a slit from the insertion side end face of the body part toward the bending side end face, and the starting point of the slit is disposed between the insertion part and the insertion part. The semiconductor device according to claim 2.   The semiconductor device according to claim 3, wherein the external electrode connection terminal has the slit accommodated in the body portion.   4. The semiconductor device according to claim 3, wherein the external electrode connection terminal has an end point of the slit larger than a width of the slit.   4. The semiconductor device according to claim 3, wherein the external electrode connection terminal has a side end face of the body portion cut out in a semicircular shape. 5.   The semiconductor device according to claim 3, wherein the external electrode connection terminal has the slit extending beyond the body portion to the attachment portion.   8. The semiconductor device according to claim 1, wherein the insertion portion of the external electrode connection terminal has a needle eye shape.   8. The semiconductor device according to claim 1, wherein a plurality of stripes extending in a longitudinal direction are processed on a surface of the insertion portion of the external electrode connection terminal. 9.   8. The semiconductor device according to claim 1, wherein the insertion portion of the external electrode connection terminal has a C-shaped cross section. 9.

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