JP2018163995A - Heat dissipating base plate for semiconductor mounting, manufacturing method and manufacturing apparatus thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the crystal grains of a metal portion of a heat dissipation base plate for semiconductor mounting from becoming coarse and highly anisotropic columnar crystals, and to suppress deformation of the heat dissipation base due to a cold heat cycle in a usage environment. SOLUTION: In the solidification cooling step, a chiller 30 connected to a cooler is brought into contact with the liquid surface of molten aluminum inside a mold 20 through a cooling opening 29, and the chiller 30 is used. Gives fine ultrasonic vibration. At this time, by pushing the cooling metal 30 according to the solidification shrinkage of the molten aluminum, it is possible to efficiently solidify the molten aluminum while controlling the cooling temperature gradient. As a result, a heat dissipation base 14 having an equiaxed crystal structure in which coarsening of crystal grains is suppressed and anisotropy is alleviated is formed, and deformation due to a thermal cycle can be suppressed. Is obtained. [Selection diagram] FIG. 8

Description

  The present invention relates to a semiconductor mounting heat dissipation base plate, and more particularly to a semiconductor mounting heat dissipation base plate including a metal circuit layer and a heat dissipation base manufactured by a casting technique, a manufacturing method thereof, and a manufacturing apparatus.

  As a heat radiation base plate for a power module, there is a metal-ceramic bonding substrate in which a metal circuit layer for mounting a power semiconductor component is bonded to one surface of an insulating ceramic substrate, and a heat dissipation base made of metal is bonded to the other surface. Used. Such a semiconductor mounting heat radiating base plate is fixed to a casing component that holds a terminal for supplying power to the power semiconductor with an adhesive, and is fastened with a bolt, a screw, or the like. In addition, metal heat radiation fins are attached to the heat radiation surface of the heat radiation base by brazing (or via heat radiation grease) to improve the heat radiation performance directly under the power semiconductor.

  As a method for manufacturing a heat dissipating base plate for semiconductor mounting, there is known molten metal bonding in which aluminum is cast so as to surround an insulating ceramic substrate installed in a mold. For example, a molten metal such as aluminum or an aluminum alloy is poured around an insulating ceramic substrate placed in a mold made of carbon, and the molten metal is solidified by cooling, so that the metal circuit layer, the insulating ceramic substrate, and the heat dissipation base are integrated. Molded.

  As a prior example of a method for manufacturing a metal-ceramic bonding substrate by molten metal bonding, Patent Document 1 discloses that a molten metal is brought into contact with a ceramic substrate in an inert gas atmosphere at the time of molten metal bonding, and then in an oxidizing gas atmosphere. It is disclosed that a molten metal is cooled and solidified. This prior example is intended to obtain a metal / ceramic bonding substrate having good dimensional accuracy by suppressing mold consumption.

  Patent Document 2 discloses a method of rapidly cooling a molten metal by pouring a cooling medium through a cooling water supply pipe penetrating the mold after pouring the molten metal into the mold. In this prior example, the metal structure is controlled by controlling the cooling rate of the molten metal, and it is intended to control the material properties such as elongation, impact value and fatigue strength, which represent the toughness of the casting.

  In addition, in an electronic device mounting substrate in which an aluminum-silicon-based aluminum alloy layer is bonded to at least one surface of an insulating substrate, the metal crystal grain size inside the aluminum alloy layer is controlled to refine the crystal grains. A technique for increasing the breaking strength at the joint interface between an insulating substrate and an aluminum alloy layer is known.

Japanese Patent No. 5478178 International Publication WO2013 / 172375

In the casting method according to Patent Document 1, directional solidification casting that suppresses internal defects such as sink marks and cracks due to solidification shrinkage is performed by cooling the molten metal in the mold from one direction by a cooling table in contact with the mold bottom surface. Yes. For this reason, there is a problem that the cooling table is in contact with the atmosphere temperature outside the mold and the mold temperature maintained at or above the molten metal temperature inside the mold, and the cooling rate is slow and the productivity is low.

  In addition, since the solidified metal crystal continues to grow from the vicinity of the cooling table, a very coarse and strongly anisotropic columnar crystal is formed in the cast product inside the mold. Such a crystal structure has a problem that it is greatly deformed by a thermal cycle in a use environment, particularly when used for a product mounting a semiconductor component such as an IGBT (Insulated Gate Bipolar Transistor). When the heat dissipation base plate is warped, excessive addition is applied to the semiconductor component joined to the metal circuit layer, which causes various defects such as destruction of the semiconductor component.

  When the metal circuit layer and the base plate are made of pure aluminum having a purity of about 99% to 99.9% by applying the manufacturing method of Patent Document 1, directivity from the downstream side of the molten metal flow at the time of molten metal joining Solidification begins and the metal structure may grow from 2 cm to more than 3 cm from downstream to upstream. As a result, a columnar crystal structure larger than the semiconductor component mounted on the metal circuit layer is formed on the surface of the base plate. The occurrence of such crystal anisotropy and crystal grain boundary defects is a starting point for destruction in various modes under the influence of changes in the product use environment, which causes quality degradation.

  Moreover, in patent document 2, since the molten metal and piping for cooling water supply with high thermal conductivity (hereinafter referred to as “cooling metal”) are in direct contact, the cooling efficiency is high and internal defects can be suppressed. At the same time, it is possible to form crystal grains near the cooled gold finely. However, since the product portion is directly cooled, there is a problem that a mark of chill remains on the product.

  Further, in Patent Document 2, although the molten metal and the chilled metal are brought into direct contact, the contact state between the molten metal and the chilled metal changes with the solidification shrinkage of the molten metal, and the cooling efficiency changes. Increasing the heat flow rate at the start of cooling increases the initial cooling temperature gradient inside the product, but the cooling temperature gradient decreases when the portion of the product far from the cooling metal solidifies. It is difficult to control the cooling temperature gradient in response to such a change in cooling efficiency.

  The present invention has been made to solve the above-described problems, and can efficiently cool the molten metal inside the mold and control the cooling temperature gradient, thereby suppressing the coarsening of crystal grains. An object of the present invention is to provide a manufacturing method and a manufacturing apparatus of a heat-dissipating base plate for semiconductor mounting.

  In addition, to obtain a heat-radiating base plate for semiconductor mounting that includes a heat-dissipating base in which the coarsening of crystal grains is suppressed and the anisotropy of metal crystals is relaxed, and which can suppress deformation due to a cooling cycle in a use environment. Objective.

  A heat dissipating base plate for semiconductor mounting according to the present invention is a heat dissipating base plate for semiconductor mounting in which a metal circuit layer for mounting a semiconductor component is bonded to one surface of an insulating ceramic substrate and a heat dissipating base is bonded to the other surface. The metal circuit layer and the heat dissipation base are made of aluminum having a purity of 99% or more and have an equiaxed crystal structure with an average crystal grain size of 5 mm or less.

Also, the method for manufacturing a semiconductor mounting heat dissipation base plate according to the present invention includes a semiconductor in which a metal circuit layer for mounting a semiconductor component is bonded to one surface of an insulating ceramic substrate and a heat dissipation base is bonded to the other surface. A method of manufacturing a heat dissipation base plate for mounting, wherein heat is provided on the opposite side of the gate to the space in which the insulating ceramic substrate is installed, the space in which the metal circuit layer and the heat dissipation base are formed, and the space in which the heat dissipation base is formed. A mold having an overflow portion communicating with a space forming a base, a cooling opening communicating with the overflow portion and the outside, and a cooling metal having an outer shape similar to the internal shape of the cooling opening is prepared. A preparation process, a molten metal supply process in which a molten metal heated to a predetermined temperature is poured into the mold from the pouring gate, and a cooling metal is pushed into the cooling opening from the outside of the mold. A solidification cooling step in which the molten metal is solidified by controlling the cooling temperature gradient of the molten metal while cooling the metal according to the solidification shrinkage of the molten metal and pushing the gold into the mold. It includes a removal processing step of removing the overflow portion trace formed integrally with the heat dissipation base from the semiconductor mounting heat dissipation base plate taken out from the mold.

  The semiconductor mounting heat dissipation base plate manufacturing apparatus according to the present invention is a semiconductor in which a metal circuit layer for mounting a semiconductor component is bonded to one surface of an insulating ceramic substrate and a heat dissipation base is bonded to the other surface. A manufacturing apparatus for manufacturing a heat radiating base plate for mounting, provided on the opposite side of the gate to the space in which the insulating ceramic substrate is installed, the space in which the metal circuit layer and the heat radiating base are formed, and the space in which the heat radiating base is formed A mold having a cooling opening that communicates with the overflow portion and the outside, and an outer shape that is connected to the cooler and is similar to the internal shape of the cooling opening. The cooling metal having, a cooling metal pushing means for pushing the cooling metal into the mold at a predetermined speed, and a gas supply for feeding the assist gas from the gate into the mold. It is those with the means.

  According to the semiconductor mounting heat dissipation base plate of the present invention, the metal circuit layer and the heat dissipation base are made of aluminum having a purity of 99% or more and have an equiaxed crystal structure with an average crystal grain size of 5 mm or less. It is possible to suppress deformation due to the cooling and heating cycle in the use environment.

  Further, according to the manufacturing method and the manufacturing apparatus of the semiconductor mounting heat dissipation base plate according to the present invention, the cooling metal is brought into contact with the liquid surface of the molten metal from the outside of the mold through the cooling opening to solidify the molten metal. By cooling the metal according to the shrinkage and pushing the gold into the mold, the molten metal can be efficiently cooled and the molten metal can be solidified while controlling the cooling temperature gradient of the molten metal. It is possible to manufacture a semiconductor mounting heat dissipation base plate including a metal circuit layer having an equiaxed crystal structure in which coarsening of grains is suppressed and anisotropy of metal crystals is relaxed, and a heat dissipation base.

It is a perspective view which shows the structure of the heat sink base plate for semiconductor mounting which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the assembly of the casting_mold | template which comprises the manufacturing apparatus of the thermal radiation base plate for semiconductor mounting concerning Embodiment 1 of this invention. It is sectional drawing which shows the molten metal supply process in the manufacturing method of the thermal radiation base board for semiconductor mounting which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the solidification cooling process in the manufacturing method of the thermal radiation base board for semiconductor mounting which concerns on Embodiment 1 of this invention. It is the perspective view and sectional drawing which show the state which took out the heat sink base board for semiconductor mounting concerning Embodiment 1 of this invention from the casting_mold | template. It is a perspective view which shows the state which implemented the fastening hole process and the removal process to the heat sink base board for semiconductor mounting concerning Embodiment 1 of this invention. It is the perspective view and sectional drawing which show the state by which the circuit groove | channel was formed in the heat sink base board for semiconductor mounting concerning Embodiment 1 of this invention. It is sectional drawing which shows the thermal radiation base plate for semiconductor mounting which concerns on Embodiment 4 of this invention.

Embodiment 1 FIG.
Hereinafter, a semiconductor mounting heat dissipation base plate, a manufacturing method thereof, and a manufacturing apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration of a semiconductor mounting heat dissipation base plate according to the first embodiment, and FIG. 2 is an assembly of molds constituting the semiconductor mounting heat dissipation base plate manufacturing apparatus according to the first embodiment. FIG. Moreover, FIG. 3 is sectional drawing which shows the molten metal supply process in the manufacturing method of the thermal radiation base board for semiconductor mounting concerning this Embodiment 1. FIG. In the drawings, the same reference numerals are given to the same and corresponding parts in the drawings.

  As shown in FIG. 1, the semiconductor mounting heat dissipation base plate 1 according to the first embodiment includes a metal circuit layer 11, an insulating ceramic substrate 12, a strength member 13, and a heat dissipation base 14. The insulating ceramic substrate 12 has a metal circuit layer 11 for mounting a semiconductor component (not shown) bonded to one surface and a heat dissipation base 14 bonded to the other surface. A strength member 13 is disposed inside the heat dissipation base 14 so as to face the insulating ceramic substrate 12. Further, a bolt fastening hole 15 having a diameter of 3 mm to 8 mm is provided in the peripheral portion of the heat dissipation base 14, and a fastening portion 16 including the bolt fastening hole 15 and its periphery is formed.

  The metal circuit layer 11 and the heat dissipation base 14 are made of aluminum having a purity of 99% or more, and have an equiaxed crystal structure with an average crystal grain size of 5 mm or less. The metal circuit layer 11 is, for example, aluminum having a thickness of 0.3 mm to 1.5 mm and a purity of 99% to 99.99%, the insulating ceramic substrate 12 is aluminum nitride having a thickness of 0.3 mm to 2.0 mm, and the strength member 13 is insulated. Aluminum nitride similar to the ceramic substrate, the heat dissipation base 14 is aluminum having a thickness of 1 mm to 5 mm and a purity of 99% to 99.99%.

  The insulating ceramic substrate 12 and the strength member 13 are manufactured by a doctor blade method, an extrusion method, or the like. The doctor blade method will be briefly described. A mixture of powdered ceramic powder, organic solvent, plasticizer, binder and the like was stirred and kneaded and transported in a slurry state. The bottom surface was composed of a thermoplastic film (hereinafter abbreviated as a film) connected to a rotating roll. Store in bathtub. By continuously pulling out the film, the slurry is extended from the gap between the bathtub and the film. This gap amount is the thickness of the plate member.

  Thereafter, the organic solvent component of the slurry on the film is volatilized to form a green body, cut into a predetermined length, or cut into a predetermined shape with a press die or the like, and peeled off from the film. The green body peeled off from the film is fixed to a boron nitride jig, heated to a predetermined temperature and fired to obtain a ceramic plate. In the extrusion molding method, a mixture of plastic and aluminum nitride is heated instead of an organic solvent, and a product having a constant cross section is continuously extruded from a die called a die. Thereafter, a ceramic plate is obtained through degreasing and firing steps of the resin and binder.

  An apparatus for manufacturing a semiconductor mounting heat dissipation base plate according to the first embodiment will be described with reference to FIGS. The semiconductor mounting heat dissipation base plate manufacturing apparatus according to the first embodiment includes an aluminum casting mold 20, a cooling metal 30 and a cooler (not shown) as cooling means, a cooling gold pushing means, and a gas supply means. (Both are not shown).

  As the material of the mold 20, graphite carbon having continuous pores and excellent air permeability is mainly used. The mold 20 includes a heat radiation surface side mold 20A and a circuit side mold 20B, and a space in which the metal circuit layer forming portion 21 that is a space for forming the metal circuit layer 11 and the insulating ceramic substrate 12 are installed. It has an insulating ceramic substrate installation part 22, a strength member installation part 23 which is a space for installing the strength member 13, and a heat dissipation base formation part 24 which is a space for forming the heat dissipation base 14.

The mold 20 has an overflow portion 28 provided on the opposite side of the pouring gate 26 with respect to the heat radiating base forming portion 24, and a cooling opening 29 that allows the overflow portion 28 to communicate with the outside. Inside the mold 20, the metal circuit layer forming part 21, the heat dissipation base forming part 24, and the overflow part 28 are in communication with each other, and the molten metal poured from the gate 26 (molten aluminum in the first embodiment) is Each space is filled through the runner 27. Note that the cooling opening 29 is desirably provided at the final filling location of the molten metal farthest from the gate 26 of the mold 20, and in the example illustrated in FIG. 3, is provided close to the final filling location.

  The cooling metal 30 connected to the cooler has an external shape similar to the internal shape of the cooling opening 29 and is inserted into the cooling opening 29 with almost no gap. The cooling metal pushing means holds the cooling metal 30 so as to be movable up and down, and pushes the cooling metal 30 inserted into the cooling opening 29 into the mold 20 at a predetermined speed. The predetermined speed is a speed determined in advance based on the solidification shrinkage of the molten aluminum, so that the cooled gold 30 can be kept in contact with the liquid surface of the molten aluminum even when the molten aluminum solidifies and shrinks. It is required by experiment or simulation.

  The chilling metal 30 controls the cooling temperature gradient of the molten aluminum in contact with the molten aluminum, and the temperature can be adjusted by a cooler so as to obtain a preset cooling temperature gradient. Further, the cooling metal 30 is held so as to pressurize the liquid level of the molten aluminum by the cooling metal pushing means in order to suppress the generation of sink marks and voids. As the cooler connected to the cooling metal 30, a cooling pump that circulates cooling water or a cooling solvent can be used, but the cooler is not limited to this. The cooler is installed outside the vacuum heating furnace. The gas supply means feeds nitrogen gas, which is assist gas, from the gate 26 into the mold 20.

  Next, a method for manufacturing a semiconductor mounting heat dissipation base plate according to the first embodiment will be described with reference to FIGS. First, as shown in FIG. 2, a metal circuit layer forming portion 21, an insulating ceramic substrate setting portion 22, a strength member setting portion 23, a heat radiation base forming portion 24, and an overflow portion 28 are included therein. A mold 20 having a cooling opening 29 communicating with each other and a cooling metal 30 having an external shape similar to the internal shape of the cooling opening 29 are prepared (preparation step).

  Subsequently, a release film is formed on the gate 26 and the runner 27 of the mold 20 in order to prevent the molten aluminum and the surface of the graphite carbon mold 20 from reacting with each other. As a method for forming a release film, for example, a release film having a thickness of 100 μm or less can be formed by spray coating a boron nitride powder diluted with a solvent such as dimethyl ether or methyl ethyl ketone. After the release film is formed, the insulating ceramic substrate 12 and the strength member 13 are respectively installed on the insulating ceramic substrate installation portion 22 and the strength member installation portion 23 of the circuit side mold 20B, and the heat radiation surface side mold 20A is placed thereon. Thereafter, the mold opening prevention screws 25 are tightened at both ends of the mold 20 to complete the mold assembling operation.

  Next, the mold 20 is put into a vacuum heating furnace (not shown), evacuated and purged with nitrogen, and then heated to about 700 ° C., which is higher than the melting temperature of aluminum. Subsequently, as shown in FIG. 3, molten aluminum (indicated by an arrow A in FIG. 3) heated to a predetermined temperature is poured from the gate 26 into the mold 20 (melt supply step). At this time, since only the water head pressure of molten aluminum does not sufficiently reach the mold 20, nitrogen gas is fed from the gate 26 and is filled while being pressurized.

  Subsequently, as shown in FIG. 4, the cooling gold 29 is pushed into the cooling opening 29 from the outside of the mold 20, and the cooling gold 30 is brought into contact with the liquid surface of the molten aluminum to control the cooling temperature gradient of the molten aluminum. Then, the molten aluminum is solidified (solidification cooling step).

  The cooling metal 30 pushed into the cooling opening 29 of the mold 20 is in direct contact with the liquid surface of the molten aluminum and absorbs the solidification latent heat of the molten aluminum. The cooling opening 29 is connected to the heat radiating base forming part 24 via the overflow part 28, and the molten aluminum is cooled at the cooling opening 29, and the surface of the molten aluminum that has come into contact with the gold 30 is the cooling start point. Solidification progresses toward

  As described above, in the method in which the cooling metal 30 is brought into direct contact with the liquid surface of the molten aluminum, compared to the conventional method (Patent Document 1) in which the mold is provided in the cooling path (Patent Document 1), and between the molten metal and the mold and the mold and the cooling metal. The thermal resistance corresponding to the thickness of the mold itself is reduced. For this reason, the cooling rate of molten aluminum is increased, the crystal grains after solidification are small, and an equiaxed crystal structure with random orientation is obtained.

  When the molten aluminum is solidified, volume shrinkage may cause sinking in which the size of the semiconductor mounting heat dissipation base plate is smaller than that of the mold 20 and voids due to solidification in the semiconductor mounting heat dissipation base plate. is there. In order to suppress the occurrence of these sink marks and voids, the cooling gold is pushed in according to the solidification shrinkage of the molten aluminum by the cooling gold pushing means from the start of cooling until the molten aluminum solidifies, and the gas supply means Thus, nitrogen gas is fed from the gate 26.

  After the solidification of the aluminum is completed and the mold 20 is cooled to near room temperature, the screws 25 are removed from the mold 20 and the semiconductor mounting heat dissipation base plate is taken out. FIG. 5A is a perspective view showing a semiconductor mounting heat dissipation base plate taken out from the mold 20, and FIG. 5B is a cross-sectional view of a portion indicated by BB in FIG. 5A. is there. The overflow trace 28a, the gate trace 26a, the runner trace 27a, etc., which are integrally formed with the heat dissipation base 14, are removed from the semiconductor mounting heat dissipation base plate shown in FIG. 5 (removal processing step).

  As the removal processing method, machining, pressing, laser cutting, ultrasonic cutting, or the like is used. Further, bolt fastening holes 15 for fastening the semiconductor mounting heat radiating base plate to other components are formed at the four corners of the heat radiating base 14 (fastening hole machining step). Since the bolt fastening hole 15 is formed by machining, pressing, or the like, the fastening hole machining process may be performed simultaneously with the removal machining process. FIG. 6 shows a semiconductor mounting heat radiating base plate in which the fastening hole processing step has been subjected to the removal processing step.

  Thereafter, as shown in FIG. 7, a part of the aluminum of the metal circuit layer 11 is removed by chemical treatment or the like to form the circuit groove 17 (circuit groove forming step). FIG. 7A is a perspective view showing a semiconductor mounting heat dissipation base plate in which circuit grooves are formed, and FIG. 7B is a cross-sectional view taken along the line CC in FIG. 7A. Thereby, a plurality of metal circuit layers 11A, 11B, 11C, and 11D (collectively, the metal circuit layer 11) divided by the circuit grooves 17 are formed on the semiconductor mounting heat dissipation base plate.

  Aluminum nitride is exposed in the circuit groove 17, and is electrically insulated with a gap between each metal circuit layer 11 and a gap between the metal circuit layer 11 and the outer heat dissipation base 14. The insulation width W of the circuit groove 17 shown in FIG. 7B is determined between the metal circuit layers 11A and 11C and the metal circuit layers 11A and 11C and the heat dissipation base 14 according to the product specifications of the semiconductor mounting heat dissipation base plate. It is determined by the potential difference generated during For example, in a circuit that generates a potential difference of a maximum of several kV, an insulation width W of about 0.5 mm to 2 mm is provided.

If it is difficult for quality control to form the circuit groove 17 only by chemical treatment, such as when the aluminum thickness of the metal circuit layer 11 is larger than the insulation width W, a part of the circuit groove 17 is formed in advance in the casting process. May be. Alternatively, from the casting to the chemical treatment process, machining such as milling using an end mill or engraving with ytterbium (Yb) fiber laser is performed, and the insulation width W of the circuit groove 17 is the chemical. You may process so that it may become larger than the aluminum thickness removed by a process.

  A metal thin film 18 capable of soldering the semiconductor component 2 is provided on a part of the metal circuit layer 11, and paste solder or the like is printed on the metal thin film 18 to form a solder layer 19. The metal thin film 18 is a nickel film by a plating process, a copper film by a cold spray, a copper film or a nickel film by a PVD process, or the like. On the metal circuit layer 11, the semiconductor component 2 is bonded via a metal thin film 18 and a solder layer 19.

  As described above, according to the method and apparatus for manufacturing a semiconductor mounting heat-radiating base plate according to the first embodiment, the cooling metal 30 connected to the cooler is transferred to the mold 20 through the cooling opening 29. Since it is made to contact directly with the molten aluminum inside, the molten metal can be cooled very efficiently, and the productivity is improved. In addition, since the cooling metal 30 is pushed in according to the solidification shrinkage of the molten aluminum, the cooling metal 30 is kept in contact with the molten aluminum inside the mold 20, and the cooling temperature gradient of the molten aluminum is controlled. It is possible to solidify while.

  In addition, until the solidification of the molten aluminum is completed, the cooling metal 30 is pushed in according to the solidification shrinkage of the molten aluminum and the nitrogen gas is fed from the gate 26. Pressure is applied from both sides on the opening 29 side, and the occurrence of sink marks and voids can be suppressed.

  For these reasons, the semiconductor mounting heat-radiating base plate 1 according to the first embodiment is made of aluminum having a purity of 99% or more, suppresses coarsening of crystal grains, and relaxes anisotropy of metal crystals. In addition, by providing the metal circuit layer 11 and the heat dissipation base 14 having an equiaxed crystal structure with an average crystal grain size of 5 mm or less, it is possible to suppress deformation due to a cooling cycle in a use environment.

  Further, since the crystal grain size around the fastening portion 16 of the heat radiating base 14 is fine, a higher fastening force can be obtained compared to a conventional heat radiating base plate having a coarse crystal grain size. Furthermore, when the overflow portion trace 28a is removed from the semiconductor mounting heat dissipation base plate taken out from the mold 20, the cooling opening trace 29a is also removed, so that the conventional problem that the trace of the cooling metal remains in the product. Is resolved.

Embodiment 2. FIG.
Since the overall configuration of the semiconductor mounting heat dissipation base plate according to the second embodiment of the present invention is the same as that of the first embodiment, description will be made with reference to FIG. In the first embodiment, aluminum nitride similar to the insulating ceramic substrate 12 is used as the strength member 13 embedded in the heat dissipation base 14 of the semiconductor mounting heat dissipation base plate 1, but in the present embodiment 2, the strength member is used. An example using a member different from the insulating ceramic substrate 12 as 13 will be described. Since the other configuration, manufacturing method, and manufacturing apparatus of the semiconductor mounting heat dissipation base plate 1 according to the second embodiment are the same as those of the first embodiment, description thereof is omitted.

  In the insulating ceramic substrate 12 bonded to the metal circuit layer 11, the substrate material is between the patterns of each metal circuit layer, and it is necessary to maintain insulation on the creeping surface. Further, high heat conductivity is required to radiate heat generated during the operation of the semiconductor component to the heat radiating base 14. However, in the semiconductor mounting heat-radiating base plate 1 having the configuration shown in FIG. 1, the strength member 13 does not need to be an insulating member.

  As a condition of the strength member 13 used for the semiconductor mounting heat dissipation base plate 1 using aluminum nitride as the insulating ceramic substrate 12 and aluminum in the metal part, the linear expansion coefficient and thermal conductivity are equivalent to those of aluminum nitride. Can be mentioned. In particular, it is important that the linear expansion coefficient is the same as that of aluminum nitride from the viewpoint of suppressing warpage of the entire heat dissipation base 14 due to the cooling / heating cycle of the heat dissipation base 14. In addition, since cast bonding in a nitrogen atmosphere is used, a material that has at least bondability with aluminum, does not impair physical properties at a temperature of about 700 ° C., which is the melting temperature of aluminum, and is chemically stable. desirable.

  In addition, when using the member which does not have joining property with aluminum, joining property with aluminum can be given by performing surface processing. For example, when using ceramics that are not bonded to aluminum, an intermediate layer that is bonded to both ceramics and aluminum is applied to the ceramic surface by high-speed flame spraying, plasma spraying, cold spraying, ion plating, infiltration and vacuum deposition. It can be formed by a physical method such as plating or a chemical method such as plating.

  Examples of the strength member 13 satisfying the above conditions include a copper-tungsten alloy, a composite alloy in which tungsten particles are dispersed in a copper matrix, a composite alloy in which metal fibers and ceramic fibers are dispersed in a metal matrix, gallium nitride, copper Examples include molybdenum, aluminum-nitrogen carbide, nitrogen carbide, aluminum carbide, and copper carbide.

  According to the second embodiment, in addition to the same effects as those of the first embodiment, the material selection range of the strength member 13 is widened, and it is possible to reduce the cost and improve the thermal conductivity.

Embodiment 3 FIG.
Since the overall configuration of the semiconductor mounting heat dissipation base plate according to the third embodiment of the present invention is the same as that of the first embodiment, description will be made with reference to FIGS. The apparatus for manufacturing a semiconductor mounting heat dissipation base plate according to the third embodiment includes an ultrasonic oscillator (not shown) that applies ultrasonic vibrations to the molten metal filled in the mold 20 via the cooling metal 30. I have.

  Using this ultrasonic oscillator, ultrasonic vibration is applied to the molten aluminum through the cooling gold 30 in the solidification cooling step. Since the other configuration and other manufacturing method of the semiconductor mounting heat dissipation base plate manufacturing apparatus according to the third embodiment are the same as those of the first embodiment, description thereof will be omitted.

  When the molten aluminum solidifies, when cooled in one direction from the cooling gold 30, columnar crystals exhibiting strong anisotropy may be formed in the crystal structure after solidification, and crystals that are the interface of the columnar crystals There is a problem that large solidification defects are likely to occur at the grain boundaries. In the first embodiment, the cooling gold 30 is solidified while controlling the cooling temperature gradient of the molten aluminum, thereby suppressing the coarsening of the crystal grains and relaxing the anisotropy of the metal crystal.

  In the third embodiment, in the solidification cooling step, the above problem is solved by applying fine ultrasonic vibration coaxially with the pushing direction while pushing the cooling metal 30 at a constant speed. Ultrasonic vibration propagates inside the aluminum sufficiently faster than the growth of columnar crystals and disturbs the crystal growth at the time of solidification, so by applying ultrasonic vibration, equiaxed grains are finer than the columnar crystals. A crystal structure can be formed. In the equiaxed crystal structure, since the individual crystal grain size is fine and the crystal orientation is random, the grain boundary defects at the crystal grain boundary are formed relatively small.

According to the third embodiment, by applying ultrasonic vibration to the molten aluminum via the cooling gold 30 in the solidification cooling step, the coarsening of the crystal grains is further suppressed than in the first embodiment, and the metal crystal The effect of alleviating the anisotropy is obtained, and the heat-radiating base plate 1 for semiconductor mounting in which all the crystal structures of the portion made of aluminum are fine equiaxed crystals can be obtained.

Embodiment 4 FIG.
FIG. 8 is a cross-sectional view showing the configuration of a semiconductor mounting heat dissipation base plate according to Embodiment 4 of the present invention. The heat dissipating base plate for semiconductor mounting according to the fourth embodiment has a plurality of cylindrical protrusions 3 as heat dissipating fins on the surface of the heat dissipating base 14 opposite to the joint surface with the insulating ceramic substrate 12. . The remaining configuration of the semiconductor mounting heat dissipation base plate according to the fourth embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

  The heat radiation surface side mold 20A (see FIG. 3) constituting the semiconductor mounting heat radiation base plate manufacturing apparatus according to the fourth embodiment has a plurality of cylindrical shapes that form heat radiation fins adjacent to the heat radiation base forming portion 24. It has a hole (not shown). Further, the side surface of each hole is tapered by 1 to 10 degrees in order to improve the releasability when releasing the product from the mold 20. Accordingly, the side surface of each protrusion 3 formed on the heat dissipation base 14 is also tapered by 1 to 10 degrees. The other configuration and manufacturing method of the semiconductor mounting heat dissipation base plate manufacturing apparatus according to the fourth embodiment are the same as those in the first embodiment, and a description thereof will be omitted.

  The semiconductor mounting heat dissipation base plate according to the fourth embodiment is a form in which heat generated in the semiconductor component 2 is directly dissipated from the protrusion 3 of the heat dissipation base 14 to the cooling medium. Since such a configuration is excellent in cooling performance, it is adopted when the shape of the radiating fin can be negotiated between the manufacturer and the user of the radiating base plate for semiconductor mounting.

  On the other hand, in Embodiment 1 described above, the heat generated by the semiconductor component 2 is cooled by sticking heat radiation fins to the heat radiation surface side of the heat radiation base 14 via heat radiation grease or the like. Such a configuration is adopted when the user of the semiconductor mounting heat dissipation base plate uses any heat dissipation fin, but because the heat generated in the semiconductor component 2 is dissipated through the heat dissipation grease, Thermal resistance is large and cooling performance is inferior.

  According to the fourth embodiment, in addition to the same effects as those of the first embodiment, the cooling performance can be improved by providing the heat radiating base 14 with a plurality of cylindrical protrusions 3 as heat radiating fins. It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  The present invention can be used as a semiconductor mounting heat dissipation base plate, particularly as a power module heat dissipation base plate.

DESCRIPTION OF SYMBOLS 1 Thermal mounting base plate for semiconductor mounting, 2 Semiconductor components, 3 Protrusion, 11 Metal circuit layer, 12
Insulating ceramic substrate, 13 strength member, 14 heat dissipation base, 15 bolt fastening hole, 16 fastening portion, 17 circuit groove, 18 metal thin film, 19 solder layer, 20 mold, 20A heat radiation surface side mold, 20B circuit side mold, 21 metal circuit Layer formation part, 22 Insulating ceramic substrate installation part, 23 Strength member installation part, 24 Radiation base formation part, 25 Screw, 26 Spout, 26a Spout trace, 27 Runway, 27a Runway trace, 28 Overflow part, 28a Overflow part trace , 29 Cooling opening, 29a Cooling opening trace, 30 Cooling gold

Claims (12)

A semiconductor mounting heat dissipation base plate in which a metal circuit layer for mounting a semiconductor component is bonded to one surface of an insulating ceramic substrate, and a heat dissipation base is bonded to the other surface,
The heat dissipation base plate for semiconductor mounting, wherein the metal circuit layer and the heat dissipation base are made of aluminum having a purity of 99% or more and have an equiaxed crystal structure with an average crystal grain size of 5 mm or less.   The heat-radiating base plate for semiconductor mounting according to claim 1, further comprising a strength member made of a material different from that of the insulating ceramic substrate and having a linear expansion coefficient equal to that of the insulating ceramic substrate.   The heat dissipating base has a plurality of cylindrical protrusions as heat dissipating fins on the surface opposite to the joint surface with the insulating ceramic substrate, and the side surface of each protrusion has a taper of 1 to 10 degrees. The heat-dissipating base plate for semiconductor mounting according to claim 1 or 2, wherein the base plate is mounted. A method of manufacturing a semiconductor mounting heat dissipation base plate in which a metal circuit layer for mounting a semiconductor component is bonded to one surface of an insulating ceramic substrate and a heat dissipation base is bonded to the other surface,
A space in which the insulating ceramic substrate is installed, a space in which the metal circuit layer and the heat dissipation base are formed, and a space that is provided on the opposite side of the gate to the space in which the heat dissipation base is formed communicate with the space that forms the heat dissipation base. A preparatory step of preparing a casting mold having a cooling opening that communicates the overflow part with the outside, and a cooling metal having an external shape similar to the internal shape of the cooling opening,
A molten metal supply step for pouring a molten metal heated to a predetermined temperature from the gate into the mold,
The molten metal is pushed from the outside of the mold into the cooling opening and brought into contact with the surface of the molten metal, and the molten metal is pushed into the mold according to the solidification shrinkage of the molten metal. A solidification cooling step for solidifying the molten metal by controlling the cooling temperature gradient of the metal, and a removal processing step for removing the overflow portion trace formed integrally with the heat dissipation base from the heat dissipation base plate for semiconductor mounting taken out from the mold A method for manufacturing a heat-radiating base plate for semiconductor mounting, comprising:   The method for producing a heat-radiating base plate for semiconductor mounting according to claim 4, wherein the molten metal is aluminum having a purity of 99% or more.   6. The method of manufacturing a heat-radiating base plate for semiconductor mounting according to claim 4, wherein in the solidification cooling step, ultrasonic vibration is applied to the molten metal through the cooling metal.   The method for manufacturing a heat-radiating base plate for semiconductor mounting according to any one of claims 4 to 6, wherein in the solidification cooling step, an assist gas is fed from the gate into the mold. A manufacturing apparatus for manufacturing a semiconductor mounting heat dissipation base plate in which a metal circuit layer for mounting a semiconductor component is bonded to one surface of an insulating ceramic substrate and a heat dissipation base is bonded to the other surface,
A space in which the insulating ceramic substrate is installed, a space in which the metal circuit layer and the heat dissipation base are formed, and a space that is provided on the opposite side of the gate to the space in which the heat dissipation base is formed communicate with the space that forms the heat dissipation base. A mold having a cooling opening that communicates the overflow part with the outside, and an overflow part
A cooling metal connected to the cooler and having an external shape similar to the internal shape of the cooling opening;
A heat dissipating device for semiconductor mounting, comprising: a cooling metal pushing means for pushing the cooling metal into the mold at a predetermined speed; and a gas supply means for feeding an assist gas from the gate into the mold. Base plate manufacturing equipment.   9. The apparatus for manufacturing a heat radiating base plate for semiconductor mounting according to claim 8, further comprising an ultrasonic oscillator for applying ultrasonic vibration to the molten metal filled in the mold through the cooling metal.   The apparatus for manufacturing a heat-radiating base plate for semiconductor mounting according to claim 8, wherein the mold includes graphite.   The mold has a plurality of cylindrical holes forming heat radiating fins adjacent to a space forming the heat radiating base, and a side surface of each hole is tapered by 1 to 10 degrees. The method for manufacturing a heat-radiating base plate for semiconductor mounting according to any one of claims 8 to 10, wherein:   12. The heat dissipation for semiconductor mounting according to claim 8, wherein the cooling opening is provided at a final filling position of the molten metal farthest from the pouring gate of the mold. Base plate manufacturing equipment.

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