JP2013135161A - Semiconductor device and manufacturing method of the same - Google Patents

Abstract

When a lead frame is used, an insulating distance between electrode terminals can be easily ensured, and a semiconductor device that can be miniaturized with low cost and excellent reliability is obtained.
A lead frame to which a semiconductor element is connected, an electrode terminal connected to the lead frame, and a part of the electrode terminal are exposed so that a part of the electrode terminal is exposed. A first sealing resin 8 for sealing the frame 1 and a second sealing resin 9 for sealing the lead frame 1 exposed from the first sealing resin 8 are provided.
[Selection] Figure 2

Description

  The present invention relates to a semiconductor device with low cost and excellent reliability.

  Among semiconductor devices, there are power semiconductor devices that handle relatively large power. Such semiconductor devices used for electric power are used for controlling and rectifying relatively large electric power in vehicles such as railway vehicles, hybrid cars, and electric vehicles, home appliances, and industrial machines. In recent years, silicon carbide (SiC), which is a wide band gap semiconductor material, has attracted attention as a semiconductor material that replaces silicon (Si), and a semiconductor element made of silicon carbide can operate stably even at a high temperature of 150 ° C. to 300 ° C. is there. For this reason, there is a demand for a power semiconductor device with excellent heat dissipation and high reliability.

  As a power semiconductor device for consumer use, a semiconductor device that uses a lead frame to which a conventional general-purpose semiconductor device technology is applied and is transfer-molded as a whole is often used. The manufacturing process of the semiconductor device using this lead frame is also highly mass-productive and is very low cost by mass production. Further, since the periphery of the semiconductor chip is covered with a hard epoxy resin by transfer molding, the reliability is very high.

  On the other hand, industrial power semiconductor devices mainly have a structure called a case type, and when a lead frame is adopted, electrode terminals are taken out from the outer peripheral portion of the semiconductor device (module) (for example, Patent Documents). 1).

Japanese Patent Laid-Open No. 11-220074 (page 3, FIG. 4, FIG. 6)

  In the conventional semiconductor device, when the lead frame is used, the electrode terminal is taken out from the outer peripheral portion of the semiconductor device. Therefore, in order to secure a predetermined insulation distance, it is necessary to ensure a wide lead interval between the lead frames. There is a problem that the size of the apparatus becomes large.

  The present invention has been made to solve the above-described problems, and provides a semiconductor device that can easily secure an insulation distance between electrode terminals and can be miniaturized.

  A lead frame to which a semiconductor element is connected, an electrode terminal connected to the lead frame, and a first element that seals the semiconductor element, the electrode terminal, and the lead frame so that a part of the electrode terminal is exposed. A semiconductor device comprising: one sealing resin; and a second sealing resin that seals the lead frame exposed from the first sealing resin.

  This invention uses a lead frame, and after the lead frame is resin-sealed with a first sealing resin, the lead frame exposed from the first sealing resin is resin-sealed with the second sealing resin. The insulation distance between the electrode terminals can be easily secured, and the semiconductor device can be downsized.

1 is a schematic top view of a semiconductor device in a first embodiment of the present invention. It is the cross-sectional schematic of the semiconductor device in the AB line | wire of FIG. 1 is a schematic cross-sectional view showing a method for manufacturing a semiconductor device in Embodiment 1 of the present invention. It is the cross-sectional schematic of the semiconductor device in Embodiment 2 of this invention. It is a cross-sectional schematic diagram which shows the manufacturing method of the semiconductor device in Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a schematic top view of a semiconductor device according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the semiconductor device taken along line AB in FIG. First, the overall configuration of the semiconductor device according to the first embodiment of the present invention will be described. As shown in FIGS. 1 and 2, the semiconductor device 11 includes a lead frame 1, a switching element 2a, a rectifying element 2b (hereinafter referred to as a semiconductor element 2), a heat spreader 3, a main electrode terminal 4a, and a signal electrode terminal. 4b (hereinafter referred to as electrode terminal 4), aluminum wire 5, sleeve 6, insulating sheet 7 (insulating layer 7a, copper foil 7b), first sealing resin 8, second sealing resin 9, external electrode terminal 10 is composed.

  The semiconductor element 2 (switching element 2a, rectifying element 2b) is fixed to a predetermined position, which is a semiconductor element connecting portion of the lead frame 1 in which the circuit pattern is configured, using a conductive bonding material (not shown) and electric Connected. The electrode formed on the surface of the semiconductor element 2, which is the opposite side of the surface where the semiconductor element 2 is fixed to the lead frame 1, is electrically connected to the lead frame 1 by a so-called wire bonding wiring member such as an aluminum wire 5. Is done. The lead frame 1 to which the aluminum wires 5 are connected is electrically connected to the outside via the cylindrical or columnar electrode terminals 4 (main electrode terminals 4a and signal electrode terminals 4b). The electrode terminal 4 is disposed substantially perpendicular to the lead frame 1. And the cylindrical sleeve 6 for ensuring the sealing performance of the electrode terminal 4 and the resin 8 which is 1st sealing resin is inserted in the outer periphery in the electrode terminal 4. As shown in FIG.

  A heat spreader 3, which is a heat radiating member for radiating heat generated from the semiconductor element 2, is fixed to the opposite side of the surface of the lead frame 1 to which the semiconductor element 2 is connected using a bonding material (not shown). Yes. Furthermore, the opposite side of the joint surface of the heat spreader 3 with the lead frame 1 is fixed to an insulating sheet 7 having a two-layer structure of an insulating layer 7a and a copper foil 7b that is a metal thin film. Then, the lead frame 1, the semiconductor element 2, the heat spreader 3, the electrode terminal 4, the aluminum wire 5, and the insulating sheet 7 are sealed using a first sealing resin 8 formed by transfer molding. At this time, the sealing is performed so that the end of the electrode terminal 4 and a part of the copper foil 7 b are exposed from the first sealing resin 8. After the sealing, the portion of the lead frame 1 protruding from the first sealing resin 8 to the outside is cut. Then, a part of the first sealing resin 8 is sealed with the second sealing resin 9 so as to cover the cut portion exposed from the first sealing resin 8 by cutting. Finally, the external electrode terminal 10 is inserted or fixed to the electrode terminal 4.

  Next, details of each member will be described. The lead frame 1 may be any material having conductivity, and copper or a copper alloy having high conductivity is particularly preferable.

  The semiconductor element 2 is fixed to the lead frame 1 using a bonding material. The bonding material may be any conductive bonding material, and examples thereof include solder, conductive adhesive, and sintered silver. The semiconductor element 2 may be a general element based on silicon, but in the present invention, a so-called wide band gap semiconductor material having a wider band gap than silicon such as silicon carbide, gallium nitride (GaN), or diamond. Is suitable for a semiconductor element using silicon carbide. The type of device is not particularly limited, but switching devices 2a such as IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors), or rectifying devices 2b such as diodes are considered. It is done.

  The heat spreader 3 is made of a metal having high thermal conductivity. For example, it is comprised with the copper board | plate material with high heat conductivity. It suffices if copper is a main component, and a metal other than copper may be contained. Also, aluminum or an alloy thereof having a light weight and high thermal conductivity may be used. Concavities and convexities may be provided on the surface so as to improve the adhesion with the first sealing resin 8. Further, in order to strengthen the chemical bond, a surface treatment such as a primer may be performed. The heat spreader 3 is fixed to the lead frame 1 on the side opposite to the surface to which the semiconductor element 2 is connected using a bonding material. In this case, the bonding material may have good thermal conductivity. In addition to the bonding materials other than those described above, an insulating high heat conductive adhesive can also be used.

  The cylindrical or columnar electrode terminal 4 is preferably a metal having good conductivity. For example, copper or a copper alloy can be used. When the shape of the electrode terminal 4 is cylindrical, a hole may be blocked on the side fixed to the lead frame 1. A cylindrical resin sleeve 6 for preventing the first sealing resin 8 from entering is inserted into the outer periphery of the electrode terminal 4. The material of the resin sleeve 6 is preferably a material that does not melt during the first sealing resin molding and can ensure strength. As the material, a thermoplastic resin such as nylon, polyparaphenylene sulfide (PPS), polybutylene terephthalate (PBT), or the like can be used. The electrode terminal 4 is fixed to the lead frame 1 with a bonding material. As the bonding material in this case, the conductive bonding material used when the lead frame 1 and the semiconductor element 2 are fixed can be used. The semiconductor element 2 and the electrode terminal 4 are electrically connected via the aluminum wire 5.

On the opposite side of the surface of the heat spreader 3 that is fixed to the lead frame 1, a thermosetting resin made of an epoxy resin or the like on the copper foil 7b surface, highly thermally conductive and insulating ceramic particles, for example, The insulating layer 7a mixed with crystalline silica, alumina, silicon nitride, boron nitride, aluminum nitride or the like as a filler is adhered. This insulating layer 7a is a resin layer having thermal conductivity and insulating properties. Since this insulating layer 7a is highly insulating, it can be used with a relatively thin thickness of 100 to 300 [mu] m, and therefore has a very high heat dissipation characteristic.
As a so-called sealing resin material constituting the first sealing resin 8, ceramic particles such as fused silica are mixed as a filler in a thermosetting resin such as an epoxy resin, and the thermal expansion coefficient and elastic modulus are adjusted. Use the selected materials.

  After the first sealing resin 8 is formed by transfer molding, a part of the lead frame 1 protruding from the first sealing resin 8 to the outside is cut. Then, a part of the first sealing resin 8 is sealed with the second sealing resin 9 so as to cover the cut portion exposed from the first sealing resin 8 by cutting the lead frame 1. This second sealing resin 9 is a resin that is liquid at room temperature, and like the first sealing resin 8, a thermosetting resin such as an epoxy resin is filled with ceramic particles such as fused silica. It is a material that is mixed with the thermal expansion coefficient and the elastic modulus. By covering the cut portion of the lead frame 1 with the second sealing resin 9, the cut portion is not exposed, and it is not necessary to widen the lead interval of the lead frame 1 in order to secure an insulation distance. Miniaturization is possible.

  An external electrode terminal 10 is connected to the electrode terminal 4. As a material of the external electrode terminal 10, a metal having good conductivity as with the electrode terminal 4 is preferable. For example, copper or a copper alloy can be used.

  Next, a method for manufacturing the semiconductor device according to the first embodiment will be described. FIG. 3 shows a manufacturing process of the semiconductor device according to the first embodiment of the present invention. As shown in FIG. 3, first, as shown in FIG. 3A, in the preparation step, a lead frame 1 serving as a base material for connecting the semiconductor element 2 and the like is prepared. Next, as shown in FIG. 3B, in the element connection step, the semiconductor element 2 (switching element 2a, rectifying element 2b) and the electrode terminal 4 (main electrode terminal 4a, signal) are formed on one surface of the lead frame 1. The electrode terminal 4b) is fixed to the surface of the lead frame 1 opposite to the surface where the semiconductor element 2 and the electrode terminal 4 are fixed with a bonding material (not shown). At this time, when solder is used as the bonding material, each member can be positioned by a fixing jig and can be manufactured by performing solder reflow in a lump.

  Next, as shown in FIG. 3C, in the wire bonding step, the electrode formed on the surface of the semiconductor element 2 and the lead frame 1 are electrically connected by the aluminum wire 5. By using the lead frame 1, the transfer efficiency between the semiconductor element connection and the wire bonding process becomes very good. Next, as shown in FIG. 3D, in the pre-sealing process, the electrode terminal 4 is prevented from entering the first sealing resin 8 in and on the electrode terminal 4 during the sealing process. The cylindrical resin sleeve 6 is inserted into the outer periphery. At this time, the resin sleeve 6 is inserted so as to protrude from the electrode terminal 4.

  Next, as shown in FIG. 3 (e), in a sealing process using a transfer mold, an insulating sheet 7 (insulating layer 7a on the copper foil 7b) is placed on the mold, and a heat spreader is placed thereon. 3 is fixed so that the insulating layer 7a and the heat spreader 3 are in contact with each other. Thereafter, the lead frame 1, the semiconductor element 2, the heat spreader 3, the electrode terminal 4, the aluminum wire 5, and the insulating sheet 7 are sealed using a first sealing resin 8 formed by transfer molding. At this time, the sealing is performed so that the end of the electrode terminal 4 and a part of the copper foil 7 b are exposed from the first sealing resin 8. The electrode terminal 4 into which the resin sleeve 6 is inserted can secure the sealing performance with the first sealing resin 8 by the movement of the resin sleeve 6 when the mold is clamped. Can be prevented. Further, the first sealing resin 8 may be prevented from entering into and above the electrode terminal 4 by other methods.

  Examples of other methods include the following. When the lead frame 1 is sandwiched between molds during transfer molding, the length of the electrode terminals 4 is adjusted so that it always contacts the molds. When the electrode terminal 4 hits, the electrode terminal 4 is deformed, so that the sealing property with the first sealing resin 8 can be secured. In this case, a cylindrical electrode terminal is better because of ease of deformation. Alternatively, a sealing property with the first sealing resin 8 is ensured by pasting a resin film in advance to a mold to which the electrode terminal 4 comes into contact and inserting the electrode terminal 4 into the resin film.

  By using the lead frame 1 and fixing a part of the lead frame 1 with a mold, the positioning of the electrode terminal 4 in the mold can be accurately performed when the first sealing resin 8 is molded. Since the positional deviation due to the injection pressure of the sealing resin 8 is very small, the positional deviation of the electrode terminal 4 in the semiconductor device 11 can be very small.

  Next, as shown in FIG. 3F, after the first sealing resin 8 used for sealing is cured in the lead frame cutting step, the lead that is exposed to the outside from the first sealing resin 8 Cut unnecessary parts of the frame 1. Then, as shown in FIG. 3G, after cutting the unnecessary part of the lead frame 1, the cut part of the lead frame 1 is sealed so as to be covered with the second sealing resin 9. When sealing with the second sealing resin 9, a mold or a frame case may be used. If the second sealing resin 9 does not sag, it is not necessary to use a mold or a frame case. good. Or you may use as an external electrode as it is, without cut | disconnecting a part of lead frame.

  Finally, as shown in FIG. 3 (h), the external electrode terminal 10 is connected to the electrode terminal 4. When the electrode terminal 4 is cylindrical, a method of inserting the external electrode terminal 10 into a cylindrical hole is preferable. Alternatively, the electrode terminal 4 and the external electrode terminal 10 may be connected not by insertion but by soldering, brazing, ultrasonic bonding, welding, or the like. The semiconductor device 11 is formed through such a manufacturing flow.

  In the semiconductor device configured as described above, conventionally, since the electrode terminal is taken out from the outer peripheral portion of the semiconductor device, it is necessary to widen the lead interval of the lead frame 1 in order to secure the insulation distance. With the lead electrode structure, it is not necessary to increase the lead interval of the lead frame 1 in order to secure the insulation distance, and the semiconductor device can be miniaturized. Further, by cutting a part of the lead frame 1 protruding from the first sealing resin 8 and resin-sealing the cut portion exposed from the first sealing resin 8 with the second sealing resin 9, The insulation distance between the leads of the lead frame 1 can be easily secured. Further, the use of the lead frame 1 improves the productivity. Further, by using the transfer mold, the adhesion between the first sealing resin 8 and each member is improved, and the reliability is improved. Furthermore, since the lead frame 1 is used, a part of the lead frame 1 is sandwiched between the molds at the time of transfer molding, so that the electrode terminals 4 can be easily positioned. Further, by using copper or a copper alloy having excellent thermal conductivity and conductivity for the lead frame 1 and the heat spreader 3, it is possible to provide a semiconductor device having excellent heat dissipation. Furthermore, by forming a semiconductor element using a wide band gap semiconductor material as a semiconductor material, high-temperature operation and power loss can be reduced, and high efficiency can be achieved.

Embodiment 2. FIG.
FIG. 4 is a schematic sectional view of a semiconductor device according to the second embodiment of the present invention. In the semiconductor device according to the second embodiment, the lead frame 21 is used in which the thickness of the lead frame at the semiconductor element connecting portion to which the semiconductor element 2 is connected is thicker on the opposite side of the surface to which the semiconductor element 2 is connected. Thus, unlike the first embodiment, the heat spreader 3 in the first embodiment is no longer necessary, and other parts are the same as those in the first embodiment.

  The overall configuration of the semiconductor device according to the second embodiment of the present invention will be described. The semiconductor device 31 uses a lead frame 21 having a different shape that is thick on the side opposite to the surface to which the semiconductor element 2 is connected as the lead frame 21. This eliminates the need for the heat spreader 3 in the first embodiment.

  FIG. 5 shows a manufacturing process of a semiconductor device according to the second embodiment of the present invention. As shown in FIG. 5, the same manufacturing process as in the first embodiment can be used as the manufacturing method. However, as described above, the heat spreader is used by using the lead frame 21 in which the thickness of the lead frame of the semiconductor element connecting portion to which the semiconductor element 2 is connected becomes thicker on the opposite side of the surface to which the semiconductor element 2 is connected. 3 becomes unnecessary, and the manufacturing process of the semiconductor device 31 can be simplified.

  In the semiconductor device configured as described above, it is not necessary to fix the heat spreader 3 to the lead frame 21 while maintaining the characteristics of the first embodiment, and the increase in thermal resistance due to the bonding material used for fixing is suppressed. And it becomes possible to simplify the fixing process at the time of manufacture.

  1,21 Lead frame, 2 Semiconductor element (2a switching element, 2b rectifier element), 3 Heat spreader, 4 Electrode terminal (4a Main electrode terminal, 4b Signal electrode terminal), 5 Aluminum wire, 6 Resin sleeve, 7 Insulation Sheet (7a insulating layer, 7b copper foil), 8 first sealing resin, 9 second sealing resin, 10 external electrode terminal, 11, 31 semiconductor device.

Claims (7)

A lead frame to which a semiconductor element is connected, an electrode terminal connected to the lead frame, and a first element that seals the semiconductor element, the electrode terminal, and the lead frame so that a part of the electrode terminal is exposed. A semiconductor device comprising: one sealing resin; and a second sealing resin that seals the lead frame exposed from the first sealing resin. The semiconductor device according to claim 1, wherein the lead frame has a heat radiating member fixed to a surface opposite to a surface to which the semiconductor element is connected. The semiconductor device according to claim 1, wherein the lead frame and the heat dissipation member are made of copper or a copper alloy. 4. The semiconductor device according to claim 1, wherein the electrode terminal has a cylindrical or columnar shape and is joined substantially perpendicularly to the lead frame. 5. The semiconductor device according to claim 1, wherein the semiconductor element is made of a wide band gap semiconductor material. 6. The semiconductor device according to claim 5, wherein the wide band gap semiconductor material is any one of silicon carbide, gallium nitride, and diamond. Connecting the semiconductor element and the electrode terminal to the lead frame, and sealing the semiconductor element, the electrode terminal, and the lead frame with a first sealing resin so that a part of the electrode terminal is exposed. Cutting a part of the lead frame protruding from the first sealing resin; cutting a part of the lead frame to remove the lead frame exposed from the first sealing resin; And a step of sealing with a second sealing resin.