JPS6223463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power semiconductor device.

Power semiconductor devices used in industrial power supplies, vehicle rectifiers, etc. are required to have a design with high reliability and a high safety factor.For this reason, conventional power semiconductor devices are designed with semiconductor elements as shown in Figure 1, for example. 1
A so-called stud type was used, in which a so-called copper stud 2 was fixed onto a so-called copper stud 2 and hermetically sealed with a glass-sealed housing 3. In this case, the cathode electrode 4, gate lead 5, etc. of the element 1 are drawn out through the glass sealing part 6 and are electrically connected to the terminals 7 and 8, respectively. Therefore, when this device is attached to a forklift, an electric vehicle, etc., it sometimes becomes an obstacle to the attachment of other devices. Furthermore, since the terminals 7 and 8 are provided adjacent to each other on the device, dust and the like may adhere to the device, causing a short circuit accident.

FIG. 2 shows another conventional power semiconductor device,
This is a pressure stud type in which a semiconductor element (pellet) 1 is pressed onto a stud 2. That is, the pellet 1 is pressed by a plurality of disc-shaped spring bodies 14 which are laminated via the lower end flat plate portion of the cathode electrode 11, an insulating plate 12, and a washer 13. The pressure of this spring body is applied to the enclosure 1 fixed to the stud 2.
This is done by a pin 16 passing through 5. The problem in this case is that in addition to the problem in FIG. Due to the difference in thickness, it was difficult to press the pellet 1 with a constant pressure. Therefore, pellet 1 and cathode electrode 1
The value of the contact thermal resistance between the electrode 1 and the stud (anode electrode) 2 differs for each product, and the large dispersion of the value causes a problem in that the yield decreases. FIG. 6 is a characteristic diagram showing the relationship between the thermal resistance R _th and the pressing force F with respect to the deflection amount l of the spring body 14. If you look at this diagram, the amount of deflection is △l
When it fluctuates, the pressure welding force fluctuates by ΔF, and the thermal resistance accordingly fluctuates by ΔRth. Thermal resistance will decrease if the amount of deflection is large and the pressure welding force is large, but there is an upper limit to the recommended value of pressure welding force, so in order to keep the thermal resistance within the standard value, the error in the amount of deflection must be suppressed to △l ₀ . I understand that this is necessary.

The present invention has been made in view of the above circumstances, and includes a conductive cooling body and a lid disposed in parallel on the upper and lower surfaces of an insulator housing a semiconductor element (pellet), and By taking out the electrode of the pellet from the side of the lid that covers the hollow part, problems such as installation space and short circuit accidents between the electrodes can be improved, and it can also be configured to press the pellet against the cooling body. The present invention aims to provide a power semiconductor device that can improve the problems that have arisen with conventional devices.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 3, reference numeral 21 denotes a conductive cooling plate made of aluminum, copper, etc., and a part of the cooling plate 21 has a baking plate whose upper and lower surfaces are parallel to each other.
A rigid annular insulator 22 made of epoxy or the like is arranged. A conductor 2 made of tungsten or the like is placed on the cooling plate 21 in the hollow part 23 of this insulator 22.
A pellet (for example, a semiconductor rectifying element) 25 is placed on the conductor 24 with its anode side facing down. A conductor 27 made of molybdenum or the like is placed on a cathode electrode 26 made of aluminum or the like provided on the pellet 25, and a conductor 28 made of copper or the like is further placed thereon.
The conductor 28 has an inverted trapezoidal lower part and a columnar protrusion above the center. The insulator 22 is separated from the cooling plate 21 by an elastic insulator (packing) 29 made of Teflon, silicone rubber, etc., which is placed between the insulator 22 and the cooling plate 21. A hole 30 is provided in the side wall of the insulator 22, and a cathode lead electrode 31 made of copper or the like is loosely inserted into the hole 30. This electrode 31
The portion located above the electrode 28 has a flat plate shape, and the protruding portion of the electrode 28 passes through that portion. On the flat plate portion 31a of the electrode 31, the electrode 28
An insulating plate 32 having a cylindrical part 32a surrounding the protruding part 28a is arranged, and plate-shaped spring bodies 33 ₁ , 33 ₂ ,
and 33 ₃ and 33 ₄ are arranged. Spring body 3
3 ₁ to 33 ₃ have a protruding portion 28a and a through hole through which the cylindrical portion 32a passes at the center thereof. A lid 35 made of metal (or an insulator may be used) that covers the hollow portion 23 is placed on the insulator 22 . This lid body 35 is
An elastic insulator (packing) made of Teflon, silicone rubber, etc. placed between this and the insulator 22
36, it is separated from the insulator 22. The cooling plate 21, the insulator 22, and the lid 35 are provided with holes passing through them, and are pressed and fixed by bolts 37 and nuts 38 inserted through the holes. Here, the lid body 35 connects the spring bodies 33 ₁ to 33 ₄
In order to press the pellets 25 toward the cooling plate 21, a pressing force can be applied to the pellets 25. In order to prevent the heads of the bolts 37 and nuts 38 from protruding outward, recesses 39 and 40 are provided in the cooling plate 21 and the lid 35.
An insulator 41 is inserted to insulate between the two. An L-shaped cathode external electrode 42 is fixed to the outer surface of the lead-out electrode 31 with a screw 43. This external electrode 42 is fixed to the insulator 22 with screws (not shown), and an elastic insulator (packing) 44 is provided between the insulator 21 and the external electrode 42.
is interposed to maintain airtightness between the two.

In the semiconductor device configured as above,
The lid body 35 and the cooling plate 21 are arranged in parallel, and the electrode 4
2 is placed on the side, there is space at the top and bottom of the device, and since the insulator 22 is provided on the end side of the cooling plate 21 and the electrode 42 is provided on the end side,
There is also a space inside the cooling plate 21, which can be used effectively. Further, since the electrodes 42 are provided on the sides where dust and the like are less likely to accumulate, it is possible to prevent short-circuit accidents of the electrodes. In addition, since the configuration has a space 45 between the insulator 22 and the cooling body 21 and a space 46 between the insulator 22 and the lid 35 through the interposition of the elastic insulators 29 and 36, the cooling plate 21, Lid body 35
The spring bodies 33 ₁ to 33 ₄ can be pressed with a predetermined pressure through the spring bodies 33 1 to 33 4 , so that the amount of deflection of the spring bodies can be made constant and the pellet 25 can be pressed. Therefore, it is possible to prevent a decrease in yield due to variation in contact thermal resistance, which has been a problem in the past. Further, since the electrode 31 is loosely inserted into the hole 30, this portion can also absorb the manufacturing difference of each component within the insulator 22.

Figure 9 is a characteristic diagram showing the relationship between the amount of deflection of the spring body and the load on the pellet side when the spring bodies are arranged in two parallel and three series as shown in the figure, and Figure 10 is the load on the 25φ pellet and the heat dissipation of the pellet. It is a characteristic diagram which shows the relationship with thermal resistance _Rth of a system. Therefore, the lower limit of the recommended load on the pellet is limited by the standard value of thermal resistance _Rth , and the upper limit is limited by the mechanical strength of the pellet side. Therefore, it is necessary to suppress the upper and lower limits of the amount of deflection of the disc-shaped spring body in accordance with the pellet load, but the allowable range of the amount of deflection is approximately 0.6 mm. on the other hand,
The dimensional error in the thickness of the dish-shaped spring body is ±0.6 mm in the example shown in Figure 9, so if the spring body is held down to a constant thickness, it is difficult to suppress the amount of deflection to the allowable width of 0.6 mm. be. On the other hand, in the configuration shown in FIG. 3, since the spaces 45 and 46 provide a space for error absorption, the bolt 37 and nut 38 can be tightened and fixed while applying the recommended load to the pellet 25 side. Therefore, the configuration shown in FIG. 3 can maintain good thermal resistance Rth and mechanical strength against pellets and the like.

FIG. 4 shows a configuration of a chopper circuit device that takes full advantage of the effect (effective use of space) obtained with the configuration of FIG. 3, and FIG. 5 shows its equivalent circuit. If you look at these figures, you can see that the electrodes of the circuit are taken out from the side and each element is arranged in high density on the cooling plate 21, and there is no need to provide electrode wiring on the upper and lower surfaces of the device, so the effectiveness is confirmed. It can be understood. In this configuration, the same reference numerals are used for parts corresponding to those in FIG. 3, appropriate subscripts are added, and explanations are omitted.

FIG. 7 shows another embodiment of the invention. The feature of this configuration is that the cylindrical spring body 51 is passed through the insulator 22, the spring body 51 is fixed with a nut 52, and the gate electrode 53 is inserted into the spring body 51.
In this case, it goes without saying that appropriate measures can be taken to ensure airtightness between the spring body 51 and the electrode lead 53. Further, in this case, the cathode externally-extracted electrode 42' is taken out from the lid 35 side. Here, the protrusion 28a of the cathode electrode 28 is connected to the spring body 3.
3 ₄ and is exposed at the bottom of a recess 54 provided in the lid 35 . The electrode 42' is introduced from the side into the recess 54 and is fixed to the electrode 28a with a screw 55. Electrode 42 and lid body 35
A packing 56 is interposed in between to maintain airtightness.

FIG. 8 shows still another embodiment of the present invention, in which a plurality of hollow portions 23 ₁ to 23 ₃ are provided in the insulator 22 between the cooling plate 21 and the lid 35, and a third
This is a realization of the configuration shown in the figure. Since the other parts correspond to those in FIG. 3, the same reference numerals are used for corresponding parts, appropriate subscripts are added, and explanations are omitted.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, only one of the spaces 45 and 46 may be provided to make the amount of deflection of the spring bodies 33 ₁ to 33 ₄ constant. Further, as a pressing means for pressing between the cooling body 21 and the lid body 35, a bolt 37 that is inserted between them is used, but for example, the screw body may be screwed into a tap that is cut halfway instead of being inserted, or the screw body may be screwed into a tap that is cut halfway, or The cooling body 21 and the lid 35 may be tightened from the outside using a shaped tightening body.

As explained above, according to the present invention, space can be used effectively, short-circuit accidents can be prevented, and the pressing force on the elements can be made constant, so that an extremely practical power semiconductor device can be realized. This is something that can be provided.

[Brief explanation of the drawing]

1 and 2 are sectional views of a conventional device, FIG. 3 is a sectional view showing the configuration of an embodiment of the present invention, FIG. 4 is a perspective view of a chopper circuit device to which the same configuration is applied, and FIG. 5 is an equivalent circuit diagram of the same device, FIG. 6 is a characteristic diagram showing the relationship between thermal resistance and pressure contact force with respect to the amount of deflection of the spring body, FIGS. 7 and 8 are cross-sectional views of different embodiments of the present invention, and FIG. FIG. 10 is a characteristic diagram that further embodies FIG. 6. 21...Cooling body, 22...Insulator, 23...Hollow part, 25...Semiconductor element, 29, 36...Elastic insulator, 31...Leading electrode, 33 ₁ to 33 ₄ ...
Spring body, 35... Lid body, 37... Bolt, 38...
... Nut, 42... External electrode, 45, 46... Space.

Claims (1)

[Claims] 1. A conductive cooling plate, an annular insulator disposed in a portion occupying a part of one main surface of the cooling plate, a semiconductor element disposed on the cooling plate within a hollow part of the insulator, and a conductor disposed on a semiconductor element and connected to an electrode of the semiconductor element; a dish-shaped spring body disposed on the conductor within a hollow part of the insulator; and a disk-shaped spring body disposed in parallel with the cooling plate a lid covering the opening of the insulator, a first sealing elastic insulator disposed between the lid and the insulator, and a space between the annular insulator and the cooling plate. A second elastic insulator for sealing is arranged, and the cover body and the cooling member are pressed so as to press the dish-shaped spring body toward the semiconductor element side and press the first and second elastic insulators for sealing. A pressing means for pressing the plate and integrating the cooling plate, the lid, and the annular insulator, and a lead-out electrode connected to the conductor and led out from the side of the annular insulator or the lid. A power semiconductor device characterized in that a space is formed between the lid body and the annular insulator, and at least one of the annular insulator and the cooling plate through the interposition of the sealing elastic insulator.