JP4479531B2 - Ceramic circuit board and semiconductor module using the same - Google Patents

Description

  The present invention relates to a technique for a ceramic circuit board and the like, and is a technique that can be effectively applied to a power semiconductor module that is particularly required to have high reliability with respect to a cooling cycle.

  The technology described below has been studied by the present inventors in completing the present invention, and the outline thereof is as follows.

  A semiconductor module such as a conventional power semiconductor module has a configuration in which a ceramic circuit board on which a semiconductor element is mounted is joined to a heat dissipation base via solder. Such a semiconductor module is required to have heat cycle resistance so as to ensure its operation in an actual use environment.

  Especially in ceramic circuit boards, ceramic substrates with different coefficients of thermal expansion and metal plates for circuit pattern formation are joined via a brazing material, so in the heat cycle test, stress relaxation based on the difference in thermal expansion coefficients is applied. If this does not work sufficiently, the ceramic circuit board is likely to be broken due to cracks at the joints.

  Therefore, various proposals have been made for the purpose of improving the heat cycle resistance. For example, in Patent Document 1, focusing on the fact that the thermal stress generated at the bonding interface between the ceramic substrate and the circuit pattern forming metal plate is largely dependent on the shape of the side surface of the metal plate, It is proposed that the angle formed between the line connecting the upper part and the upper end part and the upper side of the metal plate should be 120 degrees or more.

  Patent Document 2 finds that heat resistance can be further improved by more strictly defining the shape of the outer peripheral portion of the metal plate, and the end face of the metal plate formed on the ceramic substrate is the metal plate. It has been proposed to incline so as to approach the ceramic substrate side as it goes to the edge.

  In Patent Document 3, focusing on the brazing material that joins the metal plate and the ceramic substrate, the occurrence of cracks is greatly reduced by joining so that the brazing material protrudes at least outside the edge of the metal plate. Proposal that you can. With regard to the bonding layer of the brazing material, the amount of protrusion from the metal plate is 0.1 to 1.0 times the thickness of the metal plate, and the angle between the bonding layer and the ceramic substrate is 90 degrees or less. It is proposed to stipulate in

On the other hand, in Patent Document 4, if the surface of the metal plate for circuit pattern formation provided on the ceramic substrate has a rough surface, a large number of voids are formed in an adhesive material such as solder. The heat generated during the operation of electronic components such as the above cannot be efficiently escaped, and in some cases, heat destruction, etc., so the surface roughness of the nickel plating layer provided on the surface of the metal plate is 10 μm or less in terms of 10-point average roughness Proposals have been made to prescribe.
JP-A-11-233903 Japanese Patent Laid-Open No. 11-322455 JP-A-10-190176 JP 2001-24296 A

  However, regarding the technology for improving the heat cycle resistance and the like in the ceramic circuit board, there are still the following problems and it cannot be said that it can be said to be sufficient.

  As described in Patent Documents 1 and 2, if the edge of the circuit pattern forming metal plate to be bonded to the ceramic substrate is inclined and the inclination angle is set to, for example, 120 degrees or more, patterning accuracy is poor when forming the circuit pattern. This has been confirmed by the inventor's implementation. The poor patterning accuracy means that the line width of the circuit pattern is outside the dimensional tolerance range. When the line width exceeds the upper limit of the dimensional tolerance, the insulation distance between circuits becomes short, resulting in insulation failure between circuits. On the other hand, when the line width of the circuit is less than the lower limit of the dimensional tolerance, the resistance of the circuit increases and heat generation in the circuit increases. Therefore, it was considered necessary to set the angle within a range that does not cause inaccuracy.

  Further, as proposed in Patent Document 3, although it is effective to protrude the brazing material used for joining the ceramic substrate and the circuit pattern forming metal plate, this portion is easily corroded by increasing the protruding portion. And the concern of metal migration in the brazing filler metal is increased. That is, if there is a large protruding portion, the portion is corroded, resulting in a corroded portion having a large area. In addition, when the protruding portion is large, the distance between the circuits is shortened, Ag in the brazing material is easily moved when a voltage is applied, and there is a problem in that conduction between the circuits occurs.

  Furthermore, regarding the plating of the surface of the circuit pattern forming metal plate, Patent Document 4 widely defines the surface roughness as 10 μm or less, but in practice, it can be used effectively uniformly over a wide range of 10 μm or less. The inventor found that this is not the case.

  That is, the present inventor considers that it is necessary to review again in various technologies that contribute to the improvement of the heat cycle resistance of ceramic circuit boards that have been proposed in the past. We thought that the cycle performance could be improved.

  The object of the present invention is to provide excellent processability with good patterning property that the line width of the circuit falls within the dimensional tolerance, and excellent heat cycle resistance that ensures high electrical insulation between the circuits. A ceramic circuit board and a semiconductor module using the same are provided.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  That is, the present invention is a ceramic circuit board having a ceramic substrate and a circuit-forming metal plate provided on the ceramic substrate via a brazing material, the upper end of the metal plate on the side wall of the end portion of the metal plate The angle formed by the line connecting the part and the lower end part and the upper surface of the metal plate is 95 degrees or more and less than 120 degrees.

  By defining the lower limit as 95 degrees or more, if it is less than 95 degrees, it is possible to prevent the end of the metal plate for circuit pattern formation from being almost acute and concentrating the electric field to easily cause sparking. Further, when the gel is sealed, if it is less than 95 degrees, voids are likely to remain in the corners, and there is a possibility that bubbles may be included in the sealing. However, by setting the angle to 95 degrees or more, such problems can be avoided.

  Furthermore, the patterning property can be ensured by setting the angle to less than 120 degrees. One index for measuring such accuracy is a process capability index (Cp value). This Cp value indicates the degree of process capability with respect to the standard width, and is defined by Cp = (upper limit value−lower limit value) / 6σ (σ: standard deviation) and dimensional tolerance / 6σ. In the present invention, this Cp value can be 1.33 or more, and it can be said that the patterning accuracy is good.

  The present invention relates to a ceramic circuit board having a ceramic substrate and a metal plate for circuit formation provided on the ceramic substrate via a brazing material, the surface roughness after plating of the side wall surface of the end portion of the metal plate. Is not less than 1 μm and not more than 8 μm. The surface roughness after plating may be considered to reflect the roughness of the underlying surface, but when the roughness of the plating surface is 1 μm or less, the roughness of the underlying surface is also 1 μm or less. There is a possibility that sufficient adhesion strength cannot be ensured. By setting the roughness of the base surface to 1 μm or more, a sufficient anchor effect can be secured and the adhesion of the plating film can be secured. In addition, if the roughness of the base surface is set to 8 μm or less, the surface roughness after plating can be controlled to 8 μm or less, and the unevenness of the plating surface roughness is reduced, and the spark property between circuits is reduced. Can be reduced. That is, when the surface roughness of the plating film is 8 μm or more, electric field concentration is likely to occur at the tip of the protrusion, and discharge is facilitated when a high voltage is applied. This point can be suppressed by setting the surface roughness after plating to 8 μm or less.

  The present invention is a ceramic circuit board having a ceramic substrate and a metal plate for circuit formation provided on the ceramic substrate via a brazing material, the brazing material being provided so as to protrude from the end of the metal plate. A migration prevention film is provided on the surface of the protruding portion of the material. In such a configuration, it is desirable that the protruding portion of the brazing material has a protruding length of 0.25 mm or more and 1 mm or less and an protruding angle of 20 degrees or more and 60 degrees or less. The migration prevention film is preferably electroless Ni—P plating having a thickness of 2 μm or more and 10 μm or less and a phosphorus concentration of 5% by mass or more and 15% by mass or less.

  If the protruding length of the brazing material protruding part is less than 0.25 mm, the stress relaxation effect is small and the heat cycle resistance is inferior, and cracks occur at the interface between the brazing material protruding part and the ceramic, and the circuit pattern exceeds 1 mm. The electrical insulation property decreases between the two. Therefore, it was determined that 0.25 mm or more and 1 mm or less were preferable. Furthermore, by providing the migration preventing film on the surface of the protruding portion, for example, migration of Ag in the brazing material can be effectively prevented. As the migration prevention film, for example, if Ni-P plating on the surface of the circuit pattern forming metal plate is used, migration prevention can be achieved at a much lower cost compared to the case of forming another type of plating film. It can also be implemented by Au plating instead of Ni-P plating.

  A semiconductor module of the present invention mounts the ceramic circuit board having any one of the above configurations, a semiconductor element mounted on a mounting portion of the ceramic circuit board on the metal plate for circuit formation, and the ceramic circuit board. And a heat dissipation base. What is necessary is just to join the ceramic circuit board and the heat dissipation base through solder, for example. By adopting such a configuration, it is possible to improve the heat cycle resistance of the semiconductor module and ensure the heat dissipation effect.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  By employing the present invention, a ceramic circuit board having improved heat cycle resistance can be provided. In addition, by using such a ceramic circuit board, the heat cycle resistance of the semiconductor module can be improved.

  By adopting the present invention, heat cycle resistance can be improved and Ag migration from the brazing material can be prevented.

  By adopting the present invention, the circuit has a good patterning property in which the line width of the circuit falls within a dimensional tolerance and a high process capability, and a high electrical insulation between the circuits is ensured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof may be omitted.

  FIG. 1 is a cross-sectional explanatory view showing the overall configuration of a ceramic circuit board according to the present invention. FIG. 2 is a partial cross-sectional explanatory view showing in detail the state of the end of the metal plate in the ceramic circuit board.

  As shown in FIG. 1, a ceramic circuit board 10 according to the present invention includes a ceramic substrate 11 functioning as an insulating layer, and a circuit pattern forming metal plate joined to one surface of the ceramic substrate 11 via a brazing material A. 12 and a heat radiating metal plate 13 joined to the other surface of the ceramic substrate 11 via a brazing material A.

The ceramic substrate 11 is constituted by, for example, a silicon nitride plate (Si ₃ N ₄ plate) 11a. The plate | board thickness of the ceramic substrate 11 should just be set to 0.2 m or more and 1 mm or less as a practical range, for example.

  The circuit pattern forming metal plate 12 is constituted by, for example, a Cu plate 12a. For example, the thickness of the circuit pattern forming metal plate 12 may be set to 0.3 mm or more and 2 mm or less as a practical range. In the case shown in FIG. 1, the circuit pattern forming metal plate 12 has a circuit pattern P formed by an etching process.

  The metal plate 13 for heat dissipation is comprised by the Cu board 13a, for example. The plate | board thickness of the metal plate 13 for thermal radiation is set to 0.3 mm or more and 2 mm or less as a practical range, for example.

  For example, an Ag—Cu—Ti-based active brazing material is used as the brazing material A for joining the ceramic substrate 11 to the circuit pattern forming metal plate 12 and the heat radiating metal plate 13. In addition, when using Ag-Cu-In-Ti and Ag-Cu-Sn-Ti brazing materials containing low melting point metals such as In and Sn, the bonding process temperature can be lowered. This ceramic circuit board bonding structure is desirable because the stress applied to the ceramic board can be reduced.

  The state of the end of the circuit pattern forming metal plate 12 or the heat radiating metal plate 13 in the ceramic circuit board 10 having such a configuration is shown in an enlarged manner in FIG. As shown in FIG. 2, the circuit pattern forming metal plate 12 or the heat radiating metal plate 13 and the ceramic substrate 11 are joined together by a brazing material A in a predetermined manner.

  In the following description, the circuit pattern forming metal plate 12 or the heat radiating metal plate 13 is indicated by a metal plate M for the sake of simplicity.

  The angle θ between the lower end M1 in contact with the brazing material A at the end of the metal plate M and the line g connecting the upper end M2 and the upper surface MS of the metal plate M as shown in FIG. , Less than 120 degrees. At the end of the metal plate M, the inclined surface of the metal plate inclined portion MK is provided so that the θ is 95 degrees or more and less than 120 degrees. The slope of such a slope does not necessarily have to be along the line g. As shown in FIG. 2, it is sufficient that the line connecting the lower end M1 and the upper end M2 satisfies the above θ, and the inner side has an arc shape. It may be a concave slope.

  By adopting such a configuration, it is possible to ensure the dimensional accuracy by the etching process of the circuit pattern forming metal plate 12, that is, the value of the process capability Cp to 1.33 or more while improving the heat cycle resistance.

  As shown in FIG. 3, in Examples 1 to 10, the thickness of the Cu plate 12a as the circuit pattern forming metal plate 12 is set to 0.3 mm, 0.6 mm, and 1.5 mm, and θ is 95 degrees. As described above, when the angle is set to be less than 120 degrees, it is confirmed that the process capability Cp is all 1.33 or more and a good dimensional accuracy is ensured. The upper side 2 dimension is taken on the upper side of the metal plate 12, and the process capability Cp indicates the degree of the process capability with respect to the standard width as described above. If this value Cp is 1.33 or more, the patterning property is improved, the yield is 99.7% or more, and the production efficiency is increased.

  Further, when the ceramic circuit board is configured as a semiconductor module, the inverter circuit including the mounted semiconductor element is covered with silicon gel and so-called gel sealing is performed. At this time, the slope of the metal plate inclined portion MK is important. This is because if bubbles are contained in the inclined surface during gel sealing, the heat conduction is lowered by the bubbles, heat diffusion is deteriorated, and a problem of heat generation occurs. In these respects, it was also confirmed that bubbles were not included in the above-mentioned θ at the time of gel sealing.

  On the other hand, as seen in Comparative Examples 1 to 6, even if the thickness of the Cu plate 12a as the circuit pattern forming metal plate 12 is set to 0.3 mm, 0.6 mm, and 1.5 mm, θ is 95 When it is set outside the range of not less than 120 degrees and less than 120 degrees, it can be seen that either the dimensional accuracy or the bubble inclusion is defective.

  Further, as shown in FIG. 2, the brazing material A protrudes outside the lower end portion M <b> 1 of the metal plate M. The protruding length L of the brazing material protruding portion A1 protrudes on the ceramic substrate 11 within a range of 0.25 mm or more and 1 mm from the lower end portion M1 of the metal plate M.

  Further, the protruding angle (α) formed by the line h connecting the tangent line A1 and the upper surface 11S of the ceramic substrate 11 passing through the lower end A2 of the protruding portion A1 contacting the ceramic substrate 11 is 20 degrees or more and 60 degrees or less. Is set.

  Although not shown, a migration preventing film is provided on the brazing filler metal protrusion A1 having such a configuration. As such a migration preventing film, for example, a plating film may be provided in order to prevent migration of Ag in the brazing material A. By setting the brazing material protruding portion A1 at the above protruding angle α and the protruding length L, the protruding surface of the brazing material protruding portion A1 is formed to be large. Therefore, this migration prevention film is provided for the first time in the present invention. did.

  FIG. 4 shows an example and a comparative example when the protruding angle α and the protruding length L of the protruding portion are changed. As in Examples 11 to 15, when the protrusion angle α was 20 to 60 ° and the protrusion length L was 0.25 to 1 mm, there was no crack after the heat cycle test, and there was no discharge between the substrates. On the other hand, even if the protrusion angle is within the specified range as in Comparative Examples 7, 9, and 10, cracks after the heat cycle occur when L is 0.2 mm or less. Further, as in Comparative Examples 8 and 12, when L was 1 mm or more, cracks were not generated, but it was found that discharge between the substrates occurred. Further, as shown in Comparative Example 11, cracks occurred when the protrusion angle was 60 ° or more.

  By the way, such a migration prevention film may be the same film as the plating film provided after the circuit pattern P is formed on the circuit pattern forming metal plate 12 by etching. That is, when the plating film is provided on the circuit pattern forming metal plate 12, the plating extends from the upper surface of the circuit pattern forming metal plate 12 to the protruding portion A1 through the metal plate inclined portion MK. Such a migration prevention film may be formed. However, in order for such a plating film to function as a migration prevention film, it is necessary to set the film thickness of the brazing material protrusion A1 to 2 μm or more and 10 μm or less.

  As such a plating film, for example, an electroless Ni—P plating film having a phosphorus concentration of 5 mass% or more and 15 mass% or less can be considered. Other examples include an Au plating film, a Pd plating film, and a Cr plating film.

  In addition, regarding such a plating film, the surface roughness of the plating surface at the metal plate inclined portion MK is set to 1 μm or more and 8 μm or less. By setting such surface roughness, for example, in the cross section of the groove-shaped circuit pattern P, it is possible to effectively prevent discharge between the opposed metal plate inclined portions MK and peel off the plating film. . The surface roughness is obtained by using, for example, an ultra-deep shape measuring microscope (KEYENCE VK-8510 laser microscope), and the metal plate inclined portion MK of the metal plate M appearing in the circuit pattern P of the metal plate for circuit pattern formation after plating. The surface roughness (maximum roughness Rmax) of the upper surface MS of the metal plate M was measured.

  From this result, when the surface roughness is larger than 8 μm, the unevenness of the plating surface becomes relatively rough, and when the gel is sealed, the gel is highly viscous so that it is difficult to enter between the unevennesses, and many bubbles are generated at the portions. As a result, heat dissipation is reduced. In addition, the electric field concentrates on the protrusions and a discharge phenomenon is likely to occur.

  On the other hand, when the thickness is 1 μm or less, the surface roughness of the base surface of the plating is 1 μm or less, and the anchor effect relating to the adhesion of the plating film cannot be sufficiently obtained, and the plating is easily peeled off.

  The effect of such surface roughness is shown in FIG. That is, in Examples 16 to 24, the thickness of the Cu plate 12a as the circuit pattern forming metal plate 12 is set to 0.3 mm, 0.6 mm, 1.2 mm, and 1.5 mm, and θ is 95 degrees or more. When the surface roughness of the metal plate inclined part MK is set to 1 μm or more and 8 μm or less in a state where the process capability Cp is all set to 1.33 or more by setting it to less than 120 degrees, the plating film is peeled off and discharged. It turns out that does not occur. Incidentally, the thickness of the plating film was set to 2 μm or more and 10 μm or less.

  On the other hand, as seen in Comparative Examples 13 to 18, the thickness of the Cu plate 12a as the circuit pattern forming metal plate 12 is set to 0.3 mm, 0.6 mm, and 1.5 mm, and θ is 95 degrees or more, Even when the process capability Cp is all set to 1.33 or more by setting it to less than 120 degrees, the surface roughness of the metal plate inclined part MK is set outside the range of 1 μm or more and 8 μm or less, or the plating thickness It was confirmed that at least one of peeling of the plating film or electric discharge occurred when the thickness was set outside the range of 2 μm or more and 10 μm or less.

  When the surface roughness of the metal inclined part MK is 1 μm or less, the plating film is easily peeled off, and when the surface roughness is 10 μm or more, the gel is difficult to enter the uneven part of the surface when encapsulating the gel. It was also found that when the plating film thickness was 10 μm or more, the film stress increased and the film was easily peeled off.

  Although the case where the Cu plate 12a is used as the circuit pattern forming metal plate 12 and the Cu plate 13a is used as the heat radiating metal plate 13 is described above, a Cu alloy plate may be used. An example of the Cu alloy plate is a Cu—Mo alloy.

  That is, even if a Cu-Mo alloy plate is used for both the circuit pattern forming metal plate 12 and the heat radiating metal plate 13, or either one of the circuit pattern forming metal plate 12 and the heat radiating metal plate 13 is Cu. -Mo alloy plate may be used and Cu plate may be used for the other.

  As shown in FIG. 6, the semiconductor module 100 configured using the ceramic circuit board 10 having such a configuration has the semiconductor element 30 as the first solder on the element mounting portion of the circuit pattern forming metal plate 12 constituting the ceramic circuit board 10. 41 is joined. The semiconductor element 30 is wire-bonded to the circuit pattern forming metal plate 12 with a wire 31 such as a gold wire 31a to form an electrical connection.

  In this way, the ceramic circuit board 10 having the circuit pattern forming metal plate 12 on which the semiconductor element 30 is mounted has the heat radiating metal plate 13 joined to the heat radiating base 20 via the second solder 42. . The heat dissipation base 20 is provided with screw holes 21 for screwing.

  The second solder 42 is performed by, for example, a reflow process. As the second solder used in the reflow process, for example, Sn-Pb solder, Sn-Ag-Cu solder, or Sn-Sb solder free Pb is used. Of course, a solder having a composition other than that may be used. However, when the solder having such a configuration is used, the ceramic circuit board 10 and the heat dissipation base 20 can be further prevented from being peeled off.

  In the configuration shown in FIG. 6, for example, the ceramic substrate 11 is configured as a silicon nitride plate 11 a having a thickness of 0.3 mm, but this may be configured as an aluminum nitride plate having a thickness of 0.6 mm. . Further, the circuit pattern forming metal plate 12 may be configured as a Cu plate 12a having a thickness of 0.4 mm, and the heat radiating metal plate 13 may be configured as a Cu plate 13a having a thickness of 0.2 mm. The ceramic substrate 11 formed of an aluminum nitride plate, the circuit pattern forming metal plate 12 and the heat radiating metal plate 13 are joined by a brazing material A, not shown.

  The ceramic circuit board 10 according to the present invention described above is manufactured according to the procedure schematically shown in FIG. That is, the constituent raw materials, solvent, and dispersion material of the ceramic circuit board 10 are ball mill mixed and pulverized in step S100. After adding and kneading a binder and a plasticizer to the mixed and pulverized raw materials, adjusting the slurry viscosity to a predetermined value, in step S200, the sheet is formed with a doctor blade with a predetermined plate thickness. In step S300, after forming, the degreased sheet is sintered in a sintering furnace in a nitrogen atmosphere at 1900 ° C. to sinter and form a silicon nitride plate 11a used as the ceramic substrate 11.

  Thereafter, in step S400, a Cu plate 12a as a circuit pattern forming metal plate 12 is formed on one surface of the ceramic substrate 11 by screen printing via a brazing material, and the heat radiating metal is disposed on the other surface via a brazing material. Cu plates 13a as the plates 13 are respectively joined. Thereafter, in step S500, the circuit pattern forming metal plate 12 on the ceramic substrate 11 is etched to form a circuit pattern. In step S600, the circuit pattern forming metal plate 12 after the circuit pattern is formed is plated, and the ceramic circuit board 10 is manufactured.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The present invention can be effectively used for improving heat cycle resistance in the field of ceramic circuit boards and semiconductor modules using the same.

It is a section explanatory view showing the whole ceramic circuit board composition which is one embodiment of the present invention. It is a partial cross section explanatory drawing which shows in detail the joining condition of the metal plate edge part in the ceramic circuit board which is one embodiment of this invention. It is explanatory drawing which shows the effectiveness of this invention in dimensional accuracy in a tabular form. It is explanatory drawing which shows the effectiveness of prescription | regulations, such as the protrusion angle of a brazing material, in a table form. It is explanatory drawing which shows the effectiveness of this invention in plating film peeling, electric discharge, etc. in a table | surface form. BRIEF DESCRIPTION OF THE DRAWINGS FIG. It is a flowchart which shows typically the manufacture procedure of the ceramic circuit board which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ceramic circuit board 11 Ceramic board 11a Silicon nitride board 11S Upper surface 12 Metal plate for circuit pattern formation 12a Cu board 13 Metal plate for heat radiation 13a Cu board 20 Heat radiation base 20a Cu board 21 Screw hole 30 Semiconductor element 31 Wire 31a Gold wire 41 1 No. solder 42 No. 2 solder 100 Semiconductor module A Brazing material A1 Brazing material protruding part A2 Lower end g line h line
L protrusion length M metal plate M1 lower end portion M2 upper end portion MK metal plate inclined portion MS upper surface α protrusion angle θ angle P circuit pattern S100, S200, S300, S400, S500, S600 step

Claims (3)

A ceramic circuit board having a ceramic substrate and a metal plate for circuit formation provided on the ceramic substrate via a brazing material,
A line connecting the upper and lower ends of the metal plate on the side wall of the end portion of the metal plate, the angle between the upper surface of the metal plate, 95 degrees or more and less than 120 degrees der is, an end of the metal plate A ceramic circuit board having a surface roughness Rmax of 1 to 8 [mu] m and a plating film having a thickness of 2 to 10 [mu] m and a surface roughness of 1 to 8 [mu] m . A ceramic circuit board according to claim 1 ;
A semiconductor element mounted on a mounting portion on the metal plate for circuit formation of the ceramic circuit board;
A heat dissipating base on which the ceramic circuit board is mounted;
A semiconductor module comprising: The semiconductor module according to claim 2, wherein the semiconductor element and the ceramic circuit board are sealed with a gel.

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