JP4546008B2 - Stack for flat semiconductor devices - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stack for a flat semiconductor element in which a laminated body in which flat semiconductor elements and heat sinks are alternately stacked is applied with an elastic pressing force (pressing force). The present invention relates to a stack for a flat semiconductor device having an improved structure for applying force.
[0002]
[Prior art]
Semiconductor conversion devices tend to have larger capacities (higher voltages), and accordingly, a large number of flat semiconductor elements have been used. The semiconductor conversion device is composed of a plurality of flat semiconductor elements, a pressurizing mechanism portion that alternately stacks heat sinks for cooling the flat semiconductor elements and applies an elastic pressing force, an insulating stud bolt as a frame, and an applied force. A large number of flat semiconductor element stacks (hereinafter simply referred to as stacks) formed of pressure support plates and the like are used as circuit components of the semiconductor conversion device.
[0003]
Hereinafter, a conventional stack example used in a semiconductor conversion device will be described with reference to FIG. The stack 1 is formed by alternately laminating a plurality of flat semiconductor elements 3 and heat sinks 4 and further arranging conductors 5 serving as electric circuit connection terminals at both ends thereof and insulating spacers 12 on the outside thereof. . An insulating stud bolt 2 for connecting and tightening between the pressure support plates 8 and 9 for supporting the both ends of the spherical seat 6 also serving as a spring mounting seat and a disc spring 7 is disposed at one end of the laminate. , And fixing nuts 13A and 13B.
[0004]
The following means are employed as a method for holding the elastic pressure force on the stack 1 configured as described above. One is to fix the lower pressure support plate 9 by tightening the fixing nut 13B attached to the insulating stud bolt 2, and then apply a predetermined pressure to the upper pressure support plate 8 by a press machine (not shown). In this state, no tensile force is applied to the insulating stud bolt 2.
[0005]
Next, the fixing nut 13A is tightened in a state of being pressurized with a press machine, the press machine is released, and the press machine is removed. As a result, tensile force and elongation are generated in the insulating stud bolt 2 as reaction force of the applied pressure. Therefore, a predetermined pressing force is applied in anticipation of the extension of the insulating stud bolt 2. Another method is to directly pressurize the fixing nut 13A of the insulating stud bolt 2 with a prescribed tightening torque.
[0006]
[Problems to be solved by the invention]
A flat semiconductor element such as a GTO, IGBT, or thyristor used in a power conversion device is laminated with a heat sink for cooling and a conductor for energization, and is used under pressure with a high load of several tens kN. In recent years, there has been a demand for downsizing of the equipment, especially due to restrictions on installation location and space, but the increase in capacity of the equipment is not only an increase in the size of parts, but also a factor that conflicts with downsizing in terms of securing an insulation distance between parts. It has become.
[0007]
Conventionally, an insulating stud bolt has been used in order to maintain the pressure contact force of the semiconductor element stack for a long period of time. In general, glass fiber reinforced plastic (FRP) is often used as the insulating stud bolt material. This material is manufactured by impregnating a glass fiber with a resin into a rod shape or by drawing, and the strength in the glass fiber direction is often higher than that of a metal.
[0008]
However, in order to use it as a structural member, when a screw or hole is processed, the glass fiber is cut and the strength is lowered. Thus, when using as an insulation stud bolt, since it is indispensable to combine with other parts, optimization of the connection and connection structure has been required.
[0009]
The present invention has been made in view of the above points, and an object of the present invention is to provide a flat semiconductor element stack using an insulating stud bolt capable of maintaining a pressure contact force for a long period of time.
[0010]
[Means for Solving the Problems]
Flat type semiconductor device stack of the present invention to achieve the above object, a laminate constructed by laminating a plurality of flat type semiconductor device and a plurality of heat sinks alternately, at least one end of the laminate An elastic body provided for pressurization, a pressure support plate disposed so as to face the laminated body and the elastic body, and a pressure support plate disposed so as to face each other . a fitting formed in a cylinder having a female thread portion on the inner surface intermediate portions, the female screw portion and a male screw portion that is screwed in the fitting is formed at an end portion, and an insulating stud bolt for connecting the said connection fitting the insulating stud bolt external thread portion and the fitting the female screw portion and 1.5 to 5 times the length of the thread diameter to withstand the shear stress due to the length of the tensile load of the screw connection Satoshi of the of Yes.
[0011]
With this configuration, the strength of the threaded portion of the insulating stud bolt can be increased.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 1, a stack 1 for a flat semiconductor element is configured as follows. That is, conductors 5 serving as electric circuit connection terminals are arranged on both sides of a laminate A constituted by alternately laminating a plurality of flat semiconductor elements 3 and heat sinks 4, and upper pressure support is supported on one conductor 5. The plate 8 is brought into contact.
[0021]
A lower pressure support plate 9 is brought into contact with the other conductor 5 via a spherical seat 6 and a disc spring 7, and both pressure support plates 8 and 9 are arranged to face each other. Each of the pressure support plates 8 and 9 is provided with through holes at, for example, four corners. The fittings 10 shown in detail in FIG. 2 are inserted into the through holes. In addition, you may provide a through-hole in two places where both the pressurization support plates 8 and 9 oppose.
[0022]
The connection fitting 10 is formed in a cylindrical shape having a stepped portion 10A that abuts and engages with the pressure support plate at one end. A screw portion 10C is formed in the middle portion of the cylindrical portion 10B. In this way, the threaded portion of the insulating stud bolt 2 having the threaded portion formed between the connecting metal fittings 10 fitted and inserted into the upper and lower pressure support plates 8 and 9 is screwed into the threaded part 10C of the connecting metal fitting 10 and tightened. Thus, the laminate A, the spherical seat 6 and the disc spring 7 arranged between the upper and lower pressure support plates 8 and 9 can be tightened with a sufficient pressure contact force.
[0023]
Here, the length of the insulating stud bolt 2 screwed into the connection fitting 10 is 1.5 to 5 times the screw diameter. According to this embodiment, the element pressure contact force acts on the thread of the insulating stud bolt 2 as a shear stress as it is. In order to withstand the shear stress, the number of screw threads to be screwed in is increased.
[0024]
In other words, it is necessary to increase the screwing length. In the case of the insulation stud bolt 2, there is a relationship as shown in FIG. 3 between the shear strength of the screw portion and the screwing length, and the shearing stress generated in the screw portion when the screwing length is 1.5 times the screw diameter = allowable. It becomes stress and the screw is not sheared, and if it is 1.5 times or more, sufficient strength is obtained.
[0025]
In this way, it can be seen that if the length of screwing the insulating stud bolt 2 into the connection fitting 10 is set to 1.5 times or more of the screw diameter, the thread portion does not shear. And since it becomes a substantially constant value at 5 times or more, if the length of the thread portion is set between 1.5 and 5 times, the screw of the insulating stud bolt 2 having sufficient strength even with a pressure contact force of several tens of kN Joining is possible.
[0026]
The outer diameter of the portion located in the cylindrical portion 10B of the connection fitting 10 connected to the tip thread portion of the insulation stud bolt 2 in the connecting portion of the insulation stud bolt 2 and the connection fitting 10 is substantially the same as the inner diameter of the cylindrical portion 10B. By performing machining so that the two fit together, the movement in the bending direction generated in the threaded portion of the insulating stud bolt 2 can be restrained by the fitting portion.
[0027]
If comprised in this way, since the largest bending stress part will become the connection metal fitting 10 end part, and it becomes difficult to produce bending stress in a thread part, the intensity | strength of the thread part of the insulation stud bolt 2 improves.
[0028]
According to the flat semiconductor element stack 1 according to the above-described embodiment, all the parts are assembled by the screw connection of only the insulating stud bolt 2 and the connection fitting 10, and the other parts are in contact or fitted. It is configured. That is, since the connection fitting 10 has only the pressure support plates 8 and 9 inserted therethrough, there is no place where the end portion of the insulating stud bolt 2 is tightened and fixed except for the portion screwed into the connection fitting 10. A slight misalignment can be absorbed by the delicate movement of the contact portion, and there is an advantage that disassembly and assembly are easy.
[0029]
Further, by adopting a structure in which the pressure contact force is supported by the stepped portion 10A of the connection fitting 10, when a tensile load is generated on the insulating stud bolt 2, the portion other than the stepped portion 10A of the connection fitting 10 is also pulled and extended. The shear stress generated in the thread of the stud bolt 2 can be relaxed.
[0030]
Further, in the connection fitting 10 shown in FIG. 2, the screw portion 10C is only an intermediate portion (the center portion in the figure) of the connection fitting 10 and is a cylindrical portion 10B that is not subjected to female threading at both ends. By setting the inner diameter of the cylindrical portion of this cylindrical portion 10B, particularly on the stepped portion 10A side, to be equal to or larger than the diameter of the valley of the female screw of the screw portion 10C (the outer diameter of the external thread), the cylindrical portion on the stepped portion 10A side The part 10B supports the tensile load with the cylindrical part 10B.
[0031]
Therefore, by selecting the outer diameter according to the pressure contact load, the shear stress generated in the thread of the insulating stud bolt 2 due to the elastic elongation of this portion can be relaxed.
[0032]
4 and 5 are diagrams showing another embodiment of the present invention. In the figure, the same parts as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted. On the upper pressure support plate 8 of the flat type semiconductor element stack 1, a bolt pressure support plate 80, which is attached through three bolts 11A, 11B, and 11C, is disposed. These bolts 11 are arranged so that the bolt 11B is positioned at the center of the stack 1, and bolts 11A and 11C are arranged at equal intervals on both sides thereof.
[0033]
The connecting metal fitting 10 has a bolt pressurizing support plate 80 and an upper pressurizing support plate 8 inserted therethrough and is screwed into the insulating stud bolt 2 to constitute the flat semiconductor element stack 1. .
[0034]
According to such an embodiment, the stack 1 can be pressed by alternately screwing the bolts 11 </ b> A, 11 </ b> B, and 11 </ b> C screwed into the bolt pressurizing support plate 80. When two of the three bolts 11, for example 11A and 11C, are screwed in, one bolt 11A is always loosened. When the bolt 11A is next screwed in, the other one is loosened. By repeating this, the flat semiconductor element 3 and the heat sink 4 can be pressed.
[0035]
By adopting a structure having such a pressure contact mechanism, the stack 1 is pressed by the reaction force by screwing the three bolts 11A, 11B, and 11C, so that the insulation stud bolt 2 is twisted or bent. It becomes possible to press-contact without.
The contents described in [Means for Solving the Problems] in the original specification of the present application will be added below.
In order to achieve the above object, according to the flat semiconductor element stack of the first invention, a laminated body constituted by alternately laminating a plurality of flat semiconductor elements and a heat sink is provided at at least one end of the laminated body. Between the pressure support plates arranged opposite to each other via an elastic body provided for pressurization, and between the pressure support plates, a connection fitting provided by being inserted into and supported by the pressure support plate, and this The connecting metal fittings are connected to each other by insulating stud bolts, and the connecting metal fittings are formed in a cylindrical shape having a threaded portion at the inner surface intermediate portion, and the threaded portion formed at the end of the insulating stud bolt at the threaded portion of the connecting metal fitting. And the length of the screw coupling portion between the insulating stud bolt and the connection fitting is 1.5 to 5 times the screw diameter.
With this configuration, the strength of the threaded portion of the insulating stud bolt can be increased.
According to the flat semiconductor element stack in the second invention, the inner diameter of the cylindrical portion of the cylindrical connection fitting is fitted with the outer diameter of the portion connected to the threaded portion of the insulating stud bolt. Features.
With this configuration, it is possible to prevent an excessive force such as a force in the bending direction from being applied to the threaded portion of the insulating stud bolt.
According to the flat semiconductor element stack of the third invention, the connection fitting into which the insulating stud bolt is screwed is disposed through the pressure support plate, and the end of the connection fitting is supported by the pressure support plate. A stack for a flat semiconductor device according to the first invention.
With this configuration, the pressure contact force (a tensile force is generated in the insulation stud bolt) is transmitted to the pressure support plate via the connection fitting, and the connection fitting is also elastically deformed together with the insulation stud bolt, so the stress generated in the thread portion of the insulation stud bolt. Can be relaxed.
According to the flat semiconductor element stack of the fourth invention, the threaded portion of the cylindrical connection fitting into which the insulating stud bolt is screwed is only the middle portion, and both sides thereof are equal to or larger than the diameter of the thread valley where the screw machining is not performed. It is characterized by a cylindrical part.
With this configuration, the cylindrical parts at both ends formed across the threaded part of the connection metal fitting, on the one hand, prevents bending of the insulation stud bolt, and the other cylindrical part receives the tensile load only from the metal part cylinder, By adjusting the thickness of the cylinder, it is possible to make use of the elastic elongation due to the tensile force so that an excessive force is not generated on the insulating stud bolt.
According to the flat semiconductor element stack of the fifth aspect of the invention, the bolt pressure support plate is disposed so as to face one pressure support plate, one at the center of the bolt pressure support plate, and the like on both sides thereof. One bolt is screwed into each interval, and the connection fitting is provided by inserting a bolt pressing support plate.
By screwing three bolts by this structure, the flat semiconductor element stack is pressed by the reaction force, so that the insulating stud bolt can be pressed without twisting or bending. In addition, a stack for a flat semiconductor element having a pressure contact mechanism is provided.
[0036]
【The invention's effect】
As described above, according to the present invention, an insulating rod made of, for example, FRP is used as an insulating stud bolt as a frame of a flat semiconductor element stack by screw connection, and can be used for a long period of time. A stack can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a stack for a flat semiconductor device showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the shape of a connection fitting coupled to an insulating stud bolt of a flat semiconductor element stack. FIG. 3 is a characteristic diagram showing the relationship between the length of an insulating stud bolt thread portion and shear stress.
FIG. 4 is a plan view of a press-contact mechanism portion of a flat semiconductor element stack showing a second embodiment of the present invention.
FIG. 5 is a front view showing a structure of a stack for a flat semiconductor element according to a second embodiment of the present invention.
FIG. 6 is a configuration diagram of a conventional flat semiconductor element stack.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stack 3 ... Flat semiconductor element 5 ... Conductor 7 ... Belleville spring 8B ... Bolt pressurization support plate 11A, B, C ... Bolt 2 ... Insulation stud bolt 4 ... Heat sink 6 ... Spherical seat 8 ... Upper pressurization support plate 9 ... Lower pressure support plate 10 ... Connection fitting 11 ... Bolt 80 ... Bolt pressure support plate

Claims (7)

A laminate formed by alternately laminating a plurality of flat semiconductor elements and a plurality of heat sinks ;
An elastic body provided for pressing the at least one end of the laminate,
A pressure support plate disposed so as to face the laminated body and the elastic body ;
A fitting provided in a cylinder having a female threaded portion at the inner surface intermediate portion, which is provided by being fitted and inserted into each of the pressure support plates disposed opposite to each other ,
A male screw portion that is screw-coupled with the female screw portion of the connection fitting is formed at an end , and includes an insulating stud bolt that connects between the connection fittings ,
It was the male screw portion and the 1.5 to 5 times the length of the thread diameter to withstand the shear stress due to tensile load length of the screw connection between the internal thread portion of the fitting of the insulating stud bolts A stack for flat semiconductor devices. The connection fitting, spur type semiconductor device according to claim 1, characterized in the inner diameter of the cylindrical portion that as in the fitting to the outer diameter of the portion leading to the male threaded portion relations of the insulating stud bolts stack. 3. The stack for a flat semiconductor element according to claim 1 , wherein the connection fitting is a cylindrical portion having a diameter equal to or greater than a diameter of a valley of the female screw portion on both sides of the female screw portion . 4. The stack for a flat semiconductor element according to claim 1 , wherein the connection fitting has a stepped portion supported at one end by the pressure support plate . 5. A bolt pressure support plate that is disposed opposite to one pressure support plate and into which the connection fitting is inserted ;
In order to press-contact the laminated body, three bolts, one on each side of which is inserted through the bolt pressure support plate,
The stack for a flat semiconductor device according to claim 1, wherein the stack for a flat semiconductor device is provided. The connection fitting is provided by being inserted into the bolt pressure support plate, and has a stepped portion supported at the one end by the bolt pressure support plate.
The stack for a flat semiconductor device according to claim 5. The insulating stud bolt is made of glass fiber reinforced plastic
The flat semiconductor element stack according to claim 1, wherein the stack is a flat semiconductor element stack.

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