JP2010287842A - High-power non-inductive resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-power non-inductive resistor which is improved in thermal conductivity and heat dissipation capability, and has a strong structure for heat cycling and superior durability against high-voltage pulses. <P>SOLUTION: The high-power non-inductive resistor is formed by stacking a resistor element 1 having a plate-shaped resistance element 2 with electrodes 3 at both ends, insulating plates for insulating the resistor element 1 from others, and a heat sink 7. Each insulating plate is formed of a pair of ceramic substrates 4, 5 stacked on both surfaces of the resistance element 2 of the resistor element 1. Liquid heat-tolerant insulating grease 6 is interposed in the resistance element 1, at the connecting planes between the resistance part 2 and the ceramic substrates 4, 5, and at the connecting plane between the heat sink 7 and the ceramic substrates 4, 5. The ceramic substrates 4, 5 and the heat sink 7 are tightly connected by a tightening means such as clamp bolts 10 and a tightening plate 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high power non-inductive resistor.

  For example, a high-power non-inductive resistor used as a resistance of a semiconductor surge absorption circuit of a high-frequency induction heating power source requires performance of small size, high power, and pulse voltage resistance.

  In general, in order for this type of high-power non-inductive resistor to exhibit the above performance, it is required to have a structure with good heat dissipation and resistance to thermal cycling. Conventionally, as this type of resistor, a plate-like resistor having a non-inductive pattern is made of a heat-resistant resin adhesive or a ceramic inorganic adhesive, and a ceramic insulating substrate having a high withstand voltage and a high thermal conductivity (hereinafter referred to as “insulating pattern”). It is known that it has an internal structure that is bonded to a ceramic heat sink and is bonded to a ceramic heat sink using a metal braze (see, for example, Patent Document 1).

  When a current flows through this resistor, the plate-like resistor generates heat, and the heat is transmitted to the ceramic substrate via the adhesive, and further to the metal heat radiating plate via the metal brazing to be radiated outside the resistor. The cooling effect can be further enhanced by joining a cooling body having high thermal conductivity to the metal heat sink or by directly flowing a cooling fluid.

JP-A-8-64404 (Claims, paragraphs 0010 and 0011, FIG. 10)

  However, in the high-power non-inductive resistor described in Patent Document 1, the conduction of heat from the resistor to the metal heat sink may deteriorate over time while the energization to the resistor is repeated. . The cause is considered to be a difference in thermal expansion coefficient between the plate members. That is, since the metal heat sink and the ceramic substrate have different coefficients of thermal expansion, the amount of expansion / contraction differs when heat is applied. The temperature of the resistor is approximately the same as the outside air temperature (20 ° C.) or the cooling water temperature (40 ° C.) before operation, but becomes high (maximum 150 ° C.) when a large current flows. In continuous operation, the steady state continues, but in intermittent operation, a rapid change in temperature occurs.

  On the other hand, a metal brazing material (for example, solder) that bonds the two has a strong adhesive strength but is elongated and weak against repeated shrinkage. For this reason, when a metal heat sink and a ceramic substrate are repeatedly expanded and contracted, there is a concern that stress is applied to the metal brazing portion each time and the bonding state deteriorates and peels off from the bonding surface.

  Also, when the ceramic substrate and the metal heat sink are bonded with metal brazing, bubbles may enter the metal brazing, causing hot spots due to the bubbles, and inefficiency in heat dissipation of that part. As a result, there is a problem that the temperature of the resistor exceeds the allowable temperature and the resistor is destroyed.

  Furthermore, in order to fix the resistor to the ceramic substrate, a high-insulation heat-resistant adhesive is necessary. However, although the emphasis was placed on the insulating performance and heat-resistant performance of this adhesive, it is considered a problem with respect to thermal conductivity. There were few things. Further, since the resistor is thin and the resistor and the ceramic substrate cannot be pressure-contacted, the thickness of the high-insulation heat-resistant adhesive must be increased, and as a result, heat is transferred from the resistor to the ceramic substrate. Thermal resistance increases and thermal conductivity decreases. Moreover, since the resistor is laminated on the adhesive applied on the ceramic substrate and dried to be bonded, there is a concern that the bonding surface with the resistor becomes non-uniform.

  Furthermore, in order to manufacture the resistor described in Patent Document 1, it is necessary to perform bonding of the resistor and the ceramic substrate and the bonding of the ceramic substrate and the heat dissipation plate in separate steps, which requires time and effort.

  The present invention has been made in view of the above circumstances. A high-power non-inductive resistor that has improved thermal conductivity and heat dissipation, has a structure that is resistant to thermal cycling, and has excellent durability against high-voltage pulses. The purpose is to provide.

  In order to solve the above-mentioned problems, the invention according to claim 1 is formed by laminating a resistor having a thin plate-like resistor portion provided with electrodes at both ends, an insulating plate and a heat radiating plate for insulating the resistor. In the high-power non-inductive resistor, the insulating plate is formed by a pair of ceramic substrates laminated on both surfaces of the resistor portion of the resistor, and the resistor, the bonding surface of the ceramic substrate and the resistor portion, and the ceramic substrate In addition, a liquid heat-resistant insulating material having thermal conductivity is interposed between the joint surfaces of the heat sink and the ceramic substrate and the heat sink are pressure-bonded by a fastening means. In this case, it is preferable to use a heat-resistant insulating high thermal conductive grease as the liquid heat-resistant insulating material having thermal conductivity (claim 2).

  With this configuration, the resistor, the pair of ceramic substrates, and the ceramic substrate and the heatsink are brought into close contact with each other through a heat-resistant insulating high heat conductive material, for example, a heat resistant insulating high heat conductive grease, without using an adhesive or solder. can do. In addition, since the resistor is sandwiched between the pair of ceramic substrates, a void such as a bubble does not occur between the resistor and the ceramic substrate.

  According to a third aspect of the present invention, in the high-power non-inductive resistor according to the first or second aspect, the tightening means includes a tightening plate laminated over one of the pair of ceramic substrates, and a tightening plate And a plurality of bolts for fastening the heat sink to both side ends sandwiching the ceramic substrate. In this case, it is preferable to interpose an intermediate presser plate between the fastening plate and the ceramic substrate.

  With such a configuration, tightening (assembly) can be facilitated. In this case, by interposing the intermediate presser plate between the clamp plate and the ceramic substrate, the clamping pressure can be distributed to the intermediate presser plate and made uniform (claim 4).

  The invention according to claim 5 is the high-power non-inductive resistor according to claim 4, wherein the pressing ridge that contacts the surface of the center part of the intermediate presser plate is in contact with the intermediate presser plate in the clamping plate. And a pair of recesses provided on both sides of the pressing projection are formed between the fastening bolts on both sides in parallel to each other.

  By comprising in this way, the bending of the clamping board in a clamping | tightening state can be suppressed and a clamping pressure can be equalized.

  According to a sixth aspect of the present invention, in the high power non-inductive resistor according to any of the third to fifth aspects, the fastening plate also serves as a heat radiating plate facing the heat radiating plate. Features.

  By comprising in this way, the heat_generation | fever which arose in the resistor can be radiated from both heat sinks.

  According to this invention, since it is configured as described above, the following remarkable effects can be obtained.

  (1) According to the first and second aspects of the present invention, a resistor and a pair of ceramic substrates and a pair of ceramic substrates and a heat-resistant insulating high-thermal conductive material, such as a heat-resistant insulating high-heat conductive grease, without using an adhesive or solder, etc. The ceramic substrate and heat sink can be in close contact with each other, improving heat conductivity and heat dissipation, achieving a structure that is resistant to thermal cycling, and providing high power non-induction that is extremely durable against high-pressure pulses. A resistor can be provided.

  (2) According to the invention described in claim 3, the fastening means comprises the fastening plate laminated on the ceramic substrate and the bolt for fastening the fastening plate and the heat radiating plate. In addition, a uniform clamping pressure can be applied to the ceramic substrate, the heat radiating plate, etc., and the thermal conductivity and heat dissipation can be improved. In this case, by interposing the intermediate presser plate between the clamping plate and the ceramic substrate, the clamping pressure can be distributed and evenly distributed to the intermediate presser plate. Improvement can be achieved (claim 4).

  (3) According to the invention described in claim 5, in addition to the above (1) to (2), the bending of the clamping plate in the tightened state can be suppressed and the clamping pressure can be made uniform. Thermal conductivity and heat dissipation can be improved.

  (4) According to the invention described in claim 6, since the heat generated in the resistor can be radiated from the heat radiating plates on both sides, in addition to the above (1) to (3), the heat dissipation can be further improved. At the same time, it has excellent durability against high-pressure pulses, and can cope with high power.

It is sectional drawing (a) which shows 1st Embodiment of the high-power noninductive resistor which concerns on this invention, and the I section expanded sectional view (b) of (a). It is sectional drawing which follows the II-II line | wire of Fig.1 (a). It is the cross section (a) which shows the resistor in this invention, and the III section enlarged sectional view (b) of (a). It is a perspective view which shows the state which attached the high power noninductive resistor which concerns on this invention to the heat sink. 1 is an exploded perspective view of a high power non-inductive resistor according to the present invention. It is sectional drawing which shows 2nd Embodiment of the high power noninductive resistor which concerns on this invention. It is a disassembled perspective view which shows the principal part of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, the case where the high-power non-inductive resistor according to the present invention is attached to a cooling means such as a water-cooled heat sink will be described.

<First Embodiment>
As shown in FIG. 1A, FIG. 2 and FIG. 5, a high-power non-inductive resistor according to the present invention includes a resistor 1 having a plate-like resistor portion 2 provided with electrode portions 3 at both ends, In addition to insulating the body 1, upper and lower ceramic substrates 4 and 5, which are a pair of lower insulating plates, and a heat sink 7 are provided. Then, a liquid heat-resistant insulating material having thermal conductivity is interposed on the bonding surface of the resistor 1, the ceramic substrates 4, 5 and the resistance portion 2, and the bonding surface of the lower ceramic substrate 5 and the heat sink 7. 5 and the heat radiating plate 7 are pressure-bonded by tightening means described later.

  In the present embodiment, a heat-resistant insulating high thermal conductive grease, that is, thermal grease 6 is used as the liquid heat-resistant insulating material having thermal conductivity. This thermal grease 6 is a grease containing silicone oil as a base and a powder having good thermal conductivity such as fine alumina.

  The resistor 1 includes an electrode portion 3 and a resistor portion 2 formed by photoetching after an electrode film is formed of nickel or tin on a thin metal plate of nichrome alloy by plating. In this case, as shown in FIG. 3, the resistance portion 2 has a non-inductive shape in which the path of the resistance portion 2 has a meandering shape having linear portions parallel to each other in order to reduce inductance as much as possible. Current is passed through a meandering resistance path, and the magnetic fields generated around the path reverse each other to cancel out the magnetic fields generated in adjacent resistance paths. Generation of electromotive force can be minimized.

  3B, the resistor 1 is formed such that the width of the pattern portion 2a is 0.40 mm, for example, and the width of the gap portion 2b is 0.50 mm, for example. Is formed with a thickness of 120 μm, and the resistor 2 is sandwiched between the ceramic substrates 4 and 5 while the gap 2b of the resistor 2 is filled with the thermal grease 6.

  A terminal 11 is connected to the electrode portions 3 at both ends of the resistance portion 2 by soldering. The terminal 11 includes, for example, a U-shaped electrode connection portion and a flat plate-like external connection portion in order to secure a sufficient joint surface with the electrode portion 3 and to obtain mechanical strength.

  The ceramic substrates 4 and 5 laminated (bonded) to the upper layer and the lower layer of the resistor 1 are formed in a rectangular shape having a thickness of 1 mm, for example. In this case, the upper ceramic substrate 4 is formed in such a size that only the electrode portion 3 of the resistor 1 is exposed, and the lower ceramic substrate 5 is formed in a size having an extra space around the resistor 1. ing. The ceramic substrates 4 and 5 are preferably made of aluminum nitride, which has high thermal conductivity, high electrical insulation, and high mechanical strength among ceramics.

  Since the surfaces of the ceramic substrates 4 and 5 are rough as shown in FIG. 1B, a gap (cavity) is formed at the joint portion with the resistance portion 2, but the ceramic substrates 4 and 5 and the resistance portion 2 Since the thermal grease 6 is interposed on the joint surface, the thermal grease 6 is filled in the joint portion between the ceramic substrates 4 and 5 and the resistor portion 2, and a cavity is generated in the joint portion between the ceramic substrates 4 and 5 and the resistor portion 2. There is nothing. Although not shown, the surface of the resistance portion 2 of the resistor 1 is also a fine rough surface, but since the thermal grease 6 is filled, no cavity is generated.

  The heat sink 7 laminated (bonded) to the lower layer of the lower ceramic substrate 5 is made of a material having excellent thermal conductivity, such as tough pitch copper. The heat radiating plate 7 is formed in, for example, a rectangular shape having a thickness of 8 mm, and a plurality of fastening bolts 10 constituting a part of fastening means described later can be screwed onto two opposing sides. Screw holes 16 are provided. In this case, two screw holes 16 are provided at opposing portions. Further, mounting holes 17 for mounting bolts 18 for joining the heat sink 7 to the water-cooled heat sink 12 are provided at the corners of the heat sink 7. Note that thermal grease 6 is interposed between the heat sink 7 and the lower ceramic substrate 5. Thereby, the thermal resistance can be lowered without generating a cavity in the joint surface between the heat sink 7 and the lower ceramic 5.

  An intermediate presser plate 9 is laminated (joined) between the upper ceramic substrate 5 and the clamping plate 8. The intermediate presser plate 9 is made of a material having excellent thermal conductivity, for example, tough pitch copper, like the heat radiating plate 7. The intermediate presser plate 9 is formed in a rectangular shape having substantially the same size as the upper ceramic substrate 4 and is formed to have a thickness of 3 mm, for example. The thermal grease 6 may be applied to the joint surface between the upper ceramic substrate 4 and the intermediate presser plate 9.

  On the upper layer of the intermediate presser plate 9, a fastening plate 8 constituting a fastening means is laminated (joined). As shown in FIGS. 2 and 4, the clamping plate 8 is stacked so that the protruding strip portion 8 a of the clamping plate 8 is in contact with the center surface of the intermediate pressing plate 9 across the intermediate pressing plate 9. The clamping plate 8 is made of a material having excellent free-cutting properties, such as tough pitch copper. The clamping plate 8 is formed in a rectangular shape having a thickness of 8 mm, for example, and the width of the end portion of the clamping plate 8 is substantially the same as the lateral width of the intermediate presser plate 9. A plurality of bolt holes 15 into which fastening bolts 10 constituting a part of fastening means described later can be screwed are provided at both end portions sandwiching the ceramic substrates 4 and 5. In this case, two bolt holes 15 are provided at both end portions.

  On the lower surface, which is the joint surface between the clamping plate 8 and the intermediate presser plate 9, are provided on both sides of the convex strip 8a that contacts the central surface portion of the intermediate presser plate 9, and the intermediate presser plate 8a. A pair of concave strips 8b that are not in contact with 9 are formed in parallel with each other between the fastening bolts 10 at both ends. Thereby, the bending of the clamping plate 8 in the clamping state by the clamping means can be suppressed, and the clamping pressure applied to the intermediate presser plate 9 can be made uniform.

  The fastening means in the present embodiment includes a fastening plate 8 laminated (joined) to one of the pair of ceramic substrates 4, 5, that is, the upper ceramic substrate 4 via an intermediate presser plate 9, and the above-described fastening plate 8. It comprises four bolts 10 that pass through bolt holes 15 provided at both end portions sandwiching the ceramic substrate 4 and are screwed into screw holes 16 provided in the heat radiating plate 7. Using the fastening means configured as described above, the resistor 1, the ceramic substrates 4, 5 and the like are laminated as described above, and the uppermost fastening plate 8 and the lowermost heat dissipation plate are fastened by the fastening bolts 10. 7 can be fastened and crimped.

  As shown in FIGS. 1A and 2, the epoxy resin 14, which will be described later, is exposed from the upper surface of the heat radiating plate 7 so as not to directly touch the electrode portion 3 of the resistor 1 and the lower portion of the terminal 11 that are heated during operation. A withstand voltage and heat resistant silicon rubber 30 is coated over the lower half of the intermediate presser plate 9. Then, as shown in FIGS. 1 (a), 2 and 4, in order to ensure the strength of the terminal 11, prevent the tightening bolt 10 from loosening and improve the insulation resistance, the entire upper part of the heat sink 7 is made of epoxy. Molded with resin 14. In this case, as indicated by an imaginary line in FIG. 1A, a rectangular frame-shaped case main body 21 placed on the upper periphery of the heat sink 7 and a lid 23 provided with a slit 22 into which the terminal 11 can be inserted. It is preferable to surround the epoxy resin 14 with an outer case 20 composed of

  The high power non-inductive resistor configured as described above can be attached to the heat sink 12. In this case, thermal grease 6 is applied to the joint surface between the heat sink 7 and the heat sink 12. Thereby, the thermal resistance can be lowered without generating a cavity in the joint surface between the heat radiating plate 7 and the heat sink 12.

  In order to attach the high-power non-inductive resistor to the heat sink 12, for example, as shown in FIGS. 1 (a), 2 and 4, a mounting bolt 18 penetrating a mounting hole 17 provided in the heat sink 7 is used. The heat sink 12 is screwed and joined. The heat sink 12 is made of a material having excellent thermal conductivity, such as tough pitch copper. As shown in FIGS. 1A and 2, the cooling effect is enhanced by flowing cooling water through the cooling water passage 12 a formed inside the heat sink 12. Here, the water-cooled heat sink 12 has been described, but it is also possible to cool by, for example, natural air cooling or forced air cooling.

  With the configuration described above, the resistor 1 and the pair of ceramic substrates 4 are interposed via the thermal grease 6 by using the fastening means using the fastening plate 8, the intermediate presser plate 9 and the fastening bolt 10. , 5 and the heat radiating plate 7, and an internal structure of the resistor that can apply a uniform clamping pressure to the ceramic substrates 4, 5, the heat radiating plate 7, and the like can be formed. As a result, thermal conductivity and heat dissipation can be improved, and a structure that is resistant to thermal cycling can be achieved, and a high-power non-inductive resistor that is extremely excellent in durability against high-voltage pulses can be provided.

<Second Embodiment>
FIG. 6 is a cross-sectional view showing a second embodiment of the high-power non-inductive resistor according to the present invention, and FIG. 7 is an exploded perspective view of the main part of the second embodiment. 6 and 7, the same members or elements as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the second embodiment, the heat sink 7 is laminated (joined) on both surfaces of the resistor to further enhance the cooling effect. In the second embodiment, the fastening plate 8 in the first embodiment is changed to a double-sided heat radiation fastening plate 13. In other words, in the second embodiment, four bolt holes 15 are formed in the double-sided heat radiation fastening plate 13 in the same manner as the fastening plate 8.

  Further, as shown in FIG. 7, the double-sided heat radiation fastening plate 13 has, on the lower surface, which is a joint surface with the intermediate presser plate 9, a ridge portion 8 a that contacts the central surface portion of the intermediate presser plate 9, A pair of concave strips 8b that are provided on both sides of the convex strip 8a and are not in contact with the intermediate presser plate 9 are formed in parallel with each other between the fastening bolts 10 at both ends. Further, a pair of bottomed grooves 8c that form a rectangular groove together with the pair of concave ridge portions 8b are provided in order to isolate the convex ridge portions 8a from the joint surface so that the bending suppression effect is effectively exhibited. The pair of bottomed grooves 8c is a recess having a deeper bottom than the recess 8b, and is formed at a position where the lateral widths of the protrusion 8a and the intermediate presser plate 9 are substantially the same length.

  In this case, the bolt hole 15 is formed by a stepped hole having a large-diameter portion 15a that accommodates the head portion 10a of the tightening bolt 10, and after being crimped by the tightening bolt 10, a material having high thermal conductivity, For example, it is desirable to make the surface of the double-sided heat radiation fastening plate 13 smooth by burying it with a plug 40 made of epoxy resin. As shown in FIG. 6, in order to ensure the strength of the terminal 11, prevent loosening of the tightening bolt 10, and improve insulation resistance, the sandwiched portion between the heat radiating plate 7 and the double-sided heat radiating tightening plate 13 is made of epoxy resin. 14 is molded.

  The high-power non-inductive resistor configured as described above can be attached to the heat sink 12 on both surfaces of the heat radiating plate 7 and the double-sided heat radiation fastening plate 13 as shown in FIG. In this case, as shown in FIG. 6 and FIG. 7, the terminal 11 is led out between the heat sink 7 and the double-sided heat radiation fastening plate 13 so as to be substantially parallel to the surface of the heat sink, thereby enabling connection to other devices. It is.

  By configuring as described above, the heat generated in the resistor 1 can be dissipated from both surfaces of the heat radiating plate 7 and the double-sided heat radiating clamping plate 13, so that it is further excellent in durability against high-pressure pulses and has a higher power. It is possible to provide a high power non-inductive resistor that can cope with the above.

1 Resistor 2 Resistor 3 Electrode 4 Upper Ceramic Substrate (Insulating Plate)
5 Lower layer ceramic substrate (insulating plate)
6 Thermal grease (liquid heat-resistant insulating material with thermal conductivity)
7 Radiating plate 8 Clamping plate 8a Convex strip 8b Concave strip 8c Bottomed groove 9 Intermediate presser plate 10 Tightening bolt 13 Double-sided heat dissipation tightening plate 15 Bolt hole 16 Screw hole

Claims (6)

In a high-power non-inductive resistor formed by laminating a resistor having a plate-like resistor portion provided with electrodes at both ends, an insulating plate and a heat radiating plate for insulating the resistor,
The insulating plate is formed by a pair of ceramic substrates laminated on both surfaces of the resistor portion of the resistor,
A liquid heat-resistant insulating material having thermal conductivity is interposed between the resistor, the bonding surface of the ceramic substrate and the resistance portion, and the bonding surface of the ceramic substrate and the heat sink,
Both the ceramic substrate and the heat radiating plate are pressure-bonded by a tightening means.
A high-power non-inductive resistor characterized by that. The high power non-inductive resistor according to claim 1,
The liquid heat-resistant insulating material having heat conductivity is a heat-resistant insulating high heat conductive grease.
A high-power non-inductive resistor characterized by that. The high power non-inductive resistor according to claim 1 or 2,
The fastening means includes a fastening plate that is stacked over one of the pair of ceramic substrates, and a plurality of bolts that fasten both side ends of the fastening plate sandwiching the ceramic substrate and the heat radiating plate. ,
A high-power non-inductive resistor characterized by that. The high power non-inductive resistor according to claim 3,
An intermediate presser plate is interposed between the clamping plate and the ceramic substrate.
A high-power non-inductive resistor characterized by that. The high power non-inductive resistor according to claim 4,
On the joint surface of the clamping plate with the intermediate presser plate, a pressing ridge that contacts the center surface of the intermediate presser plate, and a pair of concave ridges provided on both sides of the pressing ridge, Formed between the fastening bolts in parallel with each other,
A high-power non-inductive resistor characterized by that. The high power non-inductive resistor according to any one of claims 3 to 5,
The fastening plate also serves as a heat sink facing the heat sink,
A high-power non-inductive resistor characterized by that.

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