JP2007088007A - Semiconductor stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily measure and control contact pressure in a laminated semiconductor element even during or after assembling of a semiconductor stack, and to suppress the degradation of a plate spring. <P>SOLUTION: The semiconductor stack is comprised of a laminated body 5 that is formed by stacking a flat semiconductor element 1 and a heat sink 2. A pair of pressing support plates 6 and 7 and a plate spring 13 interposed between either of the pressing support plates 6 and 7 and the laminated body 5 are provided on both sides in the lamination direction of the laminated body 5, and the laminated body 5 is tightened by them. The plate spring 13 is provided with a cup-shaped spring guide 14 to house the plate spring 13, and a pushing rod 15 is provided between the plate spring 13 and the pressing support plate 7 so as to compress the plate spring 13. When the laminated body 5 is tightened, a gap G between the pressing support plate 7 and the release end 14a of the plate spring guide 14 becomes small. Thus, the gap size is used to measure the quantity of compression of the plate spring 13 as well as control the contact pressure of the semiconductor element 1 of the laminated body 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor stack in which a flat semiconductor element and a heat sink are stacked.

  The semiconductor stack is configured by alternately stacking at least one flat semiconductor element and a heat sink. In this type of semiconductor stack, it is required to use a flat semiconductor element under a specified pressure contact force, and there are various types of flat semiconductor elements used such as GTO, IEGT, thyristor, diode, etc. Since the pressure contact surface shape, pressure contact area, pressure contact force, and the like of the semiconductor element are various, it is necessary to make the applied pressure different.

In the conventional semiconductor stack, as a means to ensure the specified pressure contact force in the semiconductor element, the management by the meter of the hydraulic press machine or the management method by the tightening torque of the stud bolt that tightens the semiconductor element via the pressure support plate is applied. It had been. In addition, a screw portion that penetrates the disc spring and the pressure support plate is provided in a portion of the disc spring interposed between the stack of the semiconductor element and the heat sink and one of the pressure support plates that fastens the stack, and this screw There has also been proposed a method for measuring and managing the pressing force from the compression amount of the disc spring by providing a scale disk for measuring the size of the gap formed when the pressure support plate is tightened and pressurized. (See Patent Document 1).
JP 2003-60161 A

  However, when controlling the applied pressure with a hydraulic press machine, it is necessary to periodically calibrate the hydraulic equipment and meters, and when managing the applied pressure with the tightening torque of the stud bolt, the work variation is large. There were problems such as. Furthermore, in the method of measuring and managing the size of the gap after pressurization using a scale disk, for example, it is difficult to measure the change in the size of the gap after a lapse of time after completion of the pressure welding assembly of the semiconductor stack. It was difficult to read the residual pressure contact force in the semiconductor element of the laminate. In addition, there is a problem that the disc spring is easily deteriorated because it is exposed to the outside air.

  The present invention has been made to solve the above-described problems, and can easily measure or manage the pressure contact force in the semiconductor element of the laminated body, regardless of whether the semiconductor stack is assembled or not. An object of the present invention is to obtain a semiconductor stack capable of suppressing deterioration of the semiconductor.

  In order to solve the above-described problems, a semiconductor stack according to the present invention includes a pair of layers disposed on both sides in the stacking direction of a stack by stacking at least one flat semiconductor element and a heat sink. In a semiconductor stack in which the laminated body is clamped via a pressure support plate and a disc spring interposed between at least one of the pressure support plate and the laminate, a cup-shaped dish that houses the disc spring A spring guide is provided, and a push rod for compressing the disc spring is provided between the disc spring and the pressure support plate.

  According to the present invention, by measuring the size of the gap between the disc spring guide and the pressure support plate with calipers or the like, the pressure contact force of the semiconductor element in the stacked body can be easily measured and managed. Further, since the disc spring is covered with the disc spring guide and is hardly exposed to the outside air, it is possible to suppress the disc spring from being deteriorated due to adhesion of dust or oxidation.

  Embodiments of the present invention will be described below. 1A to 1C show a semiconductor stack according to a first embodiment of the present invention, where FIG. 1A is a front view thereof, FIG. 1B is a plan view of FIG. 1A, and FIG. It is a side view of (a). In FIG. 1, in the present embodiment, a case where IEGT is adopted as a flat semiconductor element will be described as an example.

  At least one semiconductor element 1 and at least one heat sink 2 for cooling the semiconductor element 1 are alternately stacked, and conductors 3 and 3 used as external terminals and an electric circuit on both sides in the stacking direction. Insulating seats 4 and 4 are provided to insulate the laminated body 5. The laminated body 5 is sandwiched between a pair of pressure support plates 6 and 7 provided on both sides in the axial direction, and stud bolts 8 and 9 disposed on both sides of the pair of pressure support plates 6 and 7 in the flat plate direction. The fixing nuts 10 and 11 are tightened and pressurized to be fixed.

  Between one pressure support plate 6 and the laminate 5, a spherical seat 12 for applying a concentrated load to the laminate 5 is disposed, and between the other pressure support plate 7 and the laminate 5. Is provided with a disc spring 13 for absorbing a change in pressure contact force due to a temperature change.

  In the present embodiment, a cup-shaped disc spring guide 14 that houses the disc spring 13 is provided between the disc spring 13 and the laminated body 5, and between the disc spring 13 and the pressure support plate 7, A push bar 15 that presses and compresses the disc spring 13 is provided. As shown in FIGS. 2 (a) to 2 (c), the disc spring guide 14 is formed of a metal or the like in a cup shape having a depth for housing and surrounding the disc spring 13, and its open end 14a. A spherical surface portion 13a for applying a concentrated load to the laminated body 5 is formed on the outer side surface of the bottom portion 14b located on the opposite side to the bottom surface 14b. As shown in FIGS. 3 (a) and 3 (b), the push rod 15 is constituted by a cylindrical metal rod or the like, and is arranged so that the tip end portion thereof is positioned in the disc spring guide 14.

  In the semiconductor stack having such a configuration, for example, one pressure support plate 6 is fixed, and the fixing nuts 10 and 11 of the stud bolts 8 and 9 on the other pressure support plate 7 are loosened. Assembling is performed by applying a predetermined pressure to the laminated body 5 through a pair of pressure support plates 6 and 7 by a machine (not shown) and tightening the fixing nuts 10 and 11 in this state. At this time, the size of the gap G between the pressure support plate 7 and the open end 14a of the disc spring guide 14 can be easily measured with calipers or the like.

  Thereby, the compression amount of the disc spring 13 at the time of assembling the semiconductor stack can be known, and the pressure contact force of the semiconductor element 1 in the stacked body 5 at this time can be known from the compression amount-pressure force characteristic value of the disc spring 13. Can do. Moreover, the size of the gap G can be measured after the semiconductor stack 5 is assembled.

  Therefore, according to the present embodiment, the size of the gap G formed between the pressure support plate 7 and the open end 14a of the disc spring guide 14 is measured regardless of whether the semiconductor stack is assembled or not. Thus, the pressure contact force of the semiconductor element 1 in the stacked body 5 can be easily measured and managed. Further, according to the present embodiment, since the disc spring 13 is covered with the disc spring guide 14, it is less likely to come into contact with the outside air, thereby suppressing the deterioration of the disc spring 13 due to adhesion of dust or oxidation. Can do.

  In the above embodiment, the pressure contact force is measured electrically by attaching a strain gauge to the side surface of the push rod 15 or by arranging a load cell in place of the push rod 15, and the measured value Can be pulled out to measure or manage the pressure contact force during the assembly of the semiconductor stack and to check the residual pressure contact force after assembly.

  4A and 4B show the push rod 25 used in the semiconductor stack according to the second embodiment of the present invention, where FIG. 4A is a front view thereof, and FIG. 4B is a side view of FIG. FIG. Here, the same reference numerals are given to the same parts as those in the first embodiment, and the duplicate description will be omitted. In FIG. 4, the present embodiment is characterized in that a scale 25 a is formed on the side surface of the cylindrical push rod 25 along the axial direction. By compressing the disc spring 13 using the push rod 25, the size of the gap G formed between the pressure support plate 7 and the open end 14a of the disc spring guide 14 can be displayed on the scale 25a. The compression amount of the disc spring 13 can be read directly without using calipers or the like, and the pressure contact force of the semiconductor element 1 in the stacked body 5 at that time can be measured.

  FIGS. 5A to 5C show a disc spring guide 24 used in a semiconductor stack according to a third embodiment of the present invention. FIG. 5A is a front view thereof, and FIG. 5B is a left side of FIG. (C) is a right side view of (a). Here, the same reference numerals are given to the same parts as those in the first embodiment, and the duplicate description will be omitted. In FIG. 5, in this embodiment, a slit 24a extending in the axial direction is formed on the side surface of the cup-shaped disc spring guide 24 so that the compression state of the disc spring accommodated therein can be visually confirmed. Has characteristics. The slit 24a can be configured to block entry of dust and the like by closing with a transparent resin or the like as necessary.

  FIG. 6 is a front view showing a main part of a semiconductor stack according to the fourth embodiment of the present invention. Here, the same reference numerals are given to the same parts as those in the first embodiment, and the duplicate description will be omitted. In FIG. 6, in the present embodiment, an O-ring 16 is interposed between the cup-shaped disc spring guide 34 and the cylindrical push bar 35 so as to block the disc spring storage space of the disc spring guide 34 from the outside air. It has the characteristics in that place. As a result, the disc spring 13 is further prevented from being deteriorated due to intrusion, adhesion, and oxidation of dust, and hysteresis is reduced.

The semiconductor stack which concerns on 1st Embodiment by this invention is shown, (a) is the front view, (b) is the top view of (a), (c) is a side view of (a). FIG. 2 shows a disc spring guide used in the semiconductor stack shown in FIG. 1, wherein (a) is a front view thereof, (b) is a left side view of (a), and (c) is a right side view of (a). The push rod used by the semiconductor stack shown in FIG. 1 is shown, (a) is the front view, (b) is the side view of (a). The push rod used with the semiconductor stack concerning a 2nd embodiment by the present invention is shown, (a) is the front view, and (b) is the side view of (a). The disc spring guide used with the semiconductor stack based on 3rd Embodiment by this invention is shown, (a) is the front view, (b) is the left view of (a), (c) is the right side of (a) FIG. It is a front view which shows the principal part of the semiconductor stack based on 4th Embodiment by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor element 2 ... Heat sink 3 ... Conductor 4 ... Insulation seat 5 ... Laminated body 6, 7 ... Pressurization support plates 8, 9 ... Stud bolts 10, 11 ... Fixing nut 12 ... Spherical seat 13 ... Disc spring 13a ... Spherical part 14, 24, 34 ... Belleville spring guides 15, 25, 35 ... Push rod 24a ... Slit 25a ... Scale 16 ... O-ring

Claims (6)

  At least one flat semiconductor element and a heat sink are stacked to form a stacked body, a pair of pressure support plates disposed on both sides in the stacking direction of the stack, and at least one of the pressure support plates In a semiconductor stack formed by tightening the laminated body via a disc spring interposed between the laminated body, a cup-shaped disc spring guide for housing the disc spring is provided and the disc spring and the pressure support plate A semiconductor stack comprising a push rod for compressing a disc spring.   The semiconductor stack according to claim 1, wherein a strain gauge is attached to the push rod.   The semiconductor stack according to claim 1, wherein a load cell is disposed in place of the push rod.   2. The semiconductor stack according to claim 1, wherein a scale capable of reading a compression amount of the disc spring is formed on the push rod.   The semiconductor stack according to claim 1, wherein a slit for confirming a state of the disc spring is formed on a side surface of the push rod.   The semiconductor stack according to claim 1, wherein an O-ring that shields the disc spring from outside air is provided in a gap between the disc spring guide and the push rod.

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