JP4237284B2 - Metal-ceramic composite member manufacturing method, manufacturing apparatus, and manufacturing mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method, a manufacturing apparatus, and a manufacturing mold for a metal-ceramic composite member in which ceramics and a metal are firmly bonded by a direct bonding force at the interface between them.
[0002]
[Prior art]
Metal-ceramics that take advantage of the characteristics of ceramics such as chemical stability, high melting point, insulation, high hardness, and relatively high thermal conductivity, and high strength, high toughness, easy processability, and conductivity of metals Composite members are widely used in automobiles, electronic devices and the like, and typical examples thereof include a rotor for an automobile turbocharger, a metal-ceramic composite substrate for mounting a high-power electronic element, and a package.
[0003]
Adhesion, plating, metallization, thermal spraying, cast-in, brazing, and DBC methods are known as the main manufacturing methods for the metal-ceramic composite member. Thus, most metal-ceramic composite substrates are manufactured by the DBC method using an alumina substrate or the metal active brazing method using an aluminum nitride substrate.
[0004]
However, in the conventional method, as a method for directly bonding a metal to an alumina substrate, a DBC method for directly bonding a copper plate is known, but a method for directly bonding aluminum has not been known so far.
[0005]
The present applicant has previously proposed a “metal-ceramic composite member manufacturing apparatus” in Japanese Patent Laid-Open No. 8-198629 as an apparatus for directly joining aluminum as a metal plate to a ceramic member.
[0006]
This apparatus includes a conveying means for continuously supplying ceramic members, a preheating portion for preheating the conveyed ceramic members, and passing the preheated ceramic members through a molten metal in a crucible to surround the ceramic members. The main part is a joining part that joins metal to at least a part of the surface and a cooling part that becomes a metal-ceramic composite member by gradually cooling the joined ceramic member to solidify the metal. It is possible to manufacture a large number of metal-ceramic composite members having characteristics.
[0007]
[Problems to be solved by the invention]
By the way, in the case of joining a thin plate-like metal to a ceramic member, there has recently been a demand for extremely strict management of the thickness uniformity of the thin plate. However, there were cases where it was not always sufficient. In addition, ceramic composite substrates that improve heat dissipation characteristics by changing the thickness of the circuit surface and heat dissipation surface have been developed. However, in the above continuous manufacturing equipment, it is highly advanced to pull out the composite substrate straight after joining. Needed technology.
[0008]
That is, the conventional apparatus has a structure in which ceramic members are continuously supplied in the horizontal direction (lateral direction) and passed through the crucible. Therefore, when a metal is bonded to the two surfaces of the plate-shaped ceramic member, the molten metal moves while contacting both surfaces of the member and is bonded at the cooling unit.
[0009]
However, in the case of ceramic composite substrates with different thicknesses on the upper and lower surfaces of the bonded metal, there is a case where the metal tends to bend in the thick direction of the bonded metal surface even though the tip is pulled horizontally with a pinch roll. It turned out that this required advanced techniques to facilitate continuous production.
[0010]
The present invention has been made under the above-mentioned background, and a manufacturing method and manufacturing for making it possible to manufacture a wide variety of metal-ceramic composite members having particularly excellent bonding characteristics at low cost. An object is to provide an apparatus and a mold for production.
[0011]
[Means for Solving the Problems]
The manufacturing method of the invention of claim 1 holds a ceramic member in a mold, and injects a molten metal to be bonded into the mold so as to be in contact with the surface of the ceramic member and solidifies by cooling. In a method for producing a metal-ceramic composite member in which a metal is bonded to the surface of a ceramic member by a direct bonding force at the interface between the ceramic and the metal, the atmosphere in the mold is maintained while the ceramic member is held in the mold. A mold atmosphere replacement step for substituting the oxygen concentration to a predetermined value or less, a preheating step for preheating the mold after the step, and maintaining the temperature in the mold at the pouring temperature after the step, and a molten metal in the mold A pouring process for filling the mold so as to fill the mold, and after the process, the temperature in the mold is lowered to a joining temperature at which the molten metal starts to solidify and exerts a joining action. A bonding step of bonding the metal to the surface of the box member, characterized in that it includes a slow cooling step of slow-cooling the mold after the process.
[0012]
According to a second aspect of the present invention, there is provided a manufacturing method according to the first aspect, wherein in the pouring step, as the mold, a molten metal inlet for introducing a molten metal into the mold, a ceramic member is held and the surface of the ceramic member is And having a narrow portion for removing an oxide film formed on the surface of the molten metal in the middle of the path from the molten metal inlet to the bonded portion. The molten metal is poured using the molten metal after the oxide film is removed by the narrowed portion.
[0013]
According to a third aspect of the present invention, in the first or second aspect, the oxygen concentration is set to 1% or less in the template atmosphere replacement step.
[0014]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the pouring temperature in the pouring step is 700 to 800 ° C.
[0015]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the bonding temperature in the bonding step is 550 to 750 ° C.
[0016]
According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the operation of lowering the temperature in the mold to the joining temperature in the joining step is such that the temperature is lowered stepwise from the bottom to the top of the mold. It is characterized by being performed.
[0017]
According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the metal is aluminum or an alloy mainly composed of aluminum.
[0018]
The manufacturing method of the invention of claim 8 is the method according to any one of claims 1 to 7, wherein the ceramic member is one of aluminum oxide, nitride, carbide, silicon oxide, nitride, and carbide. Features.
[0019]
The manufacturing apparatus of the invention of claim 9 holds the ceramic member in the mold, and injects the molten metal to be joined into the mold so as to contact the surface of the ceramic member, and solidifies by cooling. In a metal-ceramic composite member manufacturing apparatus that joins metal to the surface of a ceramic member by direct bonding force at the interface between ceramic and metal, the atmosphere in the mold is maintained with the ceramic member held in the mold. A mold atmosphere replacement section having an atmosphere replacement means for substituting and reducing the oxygen concentration to a predetermined value, a preheating section having a temperature control means for preheating the mold after the template atmosphere replacement is performed in the mold atmosphere replacement section, A temperature control means for maintaining the temperature in the mold preheated in the preheating section at the pouring temperature, and a pouring hand for pouring the molten metal into the mold so as to fill the mold. A cooling joint that joins the metal to the ceramic by lowering the temperature in the mold poured by the pouring part to a joining temperature at which the molten metal starts to solidify and exhibits a joining action, And a slow cooling part for gradually cooling the mold.
[0020]
According to a tenth aspect of the present invention, there is provided the manufacturing apparatus according to the ninth aspect, wherein the mold atmosphere replacement part replaces the atmosphere in the mold with an inert gas atmosphere.
[0021]
The manufacturing apparatus according to an eleventh aspect of the present invention is the manufacturing apparatus according to the ninth or tenth aspect, wherein the cooling unit includes a heating unit that heats the mold from the side and a cooling unit that cools the mold from the bottom. And
[0022]
The mold for production of the invention of claim 12 holds a ceramic member in the mold, and injects a molten metal to be joined into the mold so as to contact the surface of the ceramic member and solidifies by cooling. In a manufacturing mold used in a method for manufacturing a metal-ceramic composite member in which a metal is bonded to the surface of a ceramic member by direct bonding force at the interface between the ceramic and the metal, a molten metal for introducing a molten metal into the mold An inlet, a joint that holds the ceramic member and secures a predetermined gap between the surface of the ceramic member and the inner wall of the mold, a molten metal passage that guides the molten metal from the molten metal inlet to the joint, A narrow portion for removing an oxide film formed on the surface of the molten metal provided at any location of the molten metal passage, and a gas vent hole provided in the joint portion When the molten metal is introduced into the mold from the molten metal inlet and supplied to the joint, the joint and the melt passage are configured so that the molten metal fills the mold. .
[0023]
According to the above-described configuration, the mold atmosphere replacement process is performed to replace the atmosphere in the mold with the ceramic member held in the mold to reduce the oxygen concentration to a predetermined value or less, and then the preheating process to preheat the mold is performed. Next, the temperature in the mold is maintained at the pouring temperature, and the molten metal is moved from one side to the other side while the molten metal is in contact with the ceramic surface while filling the mold. Then, the temperature in the mold is lowered to the bonding temperature at which the molten metal begins to solidify and the bonding effect is exerted, and the bonding process is performed to bond the metal to the surface of the ceramic member. Then, by performing the slow cooling process of gradually cooling the mold, the direct bonding force at the interface between the ceramic and the metal can be made extremely strong. Face and Even when joining thin metal plates with different thicknesses on both sides, such as joining thin metal plates and heat sinking surfaces, it is easy to achieve high accuracy by making the mold accuracy appropriate. It is possible to join thin metal plates having a uniform thickness. In addition, in the preheating process, the pouring process, and the joining process, the temperature is set appropriately, so that excessive thermal stress is not applied to the ceramic member, and therefore, there is no possibility of breakage due to the thermal stress.
[0024]
Further, as a mold, there is a melt introduction port for introducing a molten metal into the mold, and a joining portion that holds the ceramic member and secures a predetermined gap between the surface of the ceramic member and the inner wall of the mold. The oxide film is removed from the joint by performing a pouring process using a material having a narrow part that removes the oxide film formed on the surface of the molten metal anywhere in the path from the mouth to the joint. It is possible to obtain a stronger bonding force by supplying only the pure metal melt that has been produced.
[0025]
The present inventors discovered that the joining force can be obtained by bringing the molten metal into contact with the ceramic surface and solidifying it by bringing it into contact under specific conditions in contrast to the conventional common sense that the joining force is not obtained. It is based on. Although the mechanism by which this bonding force is obtained has not yet been fully elucidated, the above specific conditions have been obtained by the inventors through trial and error.
[0026]
That is, it is advantageous to obtain a strong joining force when the oxygen concentration in the joining site and the surrounding atmosphere is as low as possible during joining, and the ceramic surface and the molten metal are moved relative to each other to rub both. It is advantageous to obtain a stronger joining force, and the metal melt to be contacted is advantageous in obtaining a strong joining force that the oxide film is removed. , Etc.
[0027]
As the metal used in the present invention, aluminum or an alloy containing aluminum as a main component can be used. In addition, as the ceramic member used in the present invention, aluminum, silicon oxide, nitride, carbide or the like can be used.
[0028]
According to these combinations, for example, when a power module substrate in which a metal thin plate serving as a circuit surface and a metal thin plate serving as a heat radiating surface are joined to both surfaces of a ceramic substrate, the heat generated between the aluminum and the ceramic substrate due to heat generated by the power module is formed. Although the expansion difference is relatively large, since the strength of aluminum is low, it is possible to obtain a material with little joint deterioration due to the thermal expansion difference.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 is a diagram showing a configuration of a metal-ceramic composite member manufacturing apparatus, FIGS. 2 to 6 are mold configuration diagrams, FIG. 2 is a perspective view of a manufacturing mold, and FIG. 3 is an arrow III-III in FIG. 4 is an exploded plan view of the mold as viewed in the viewing direction, FIG. 4 is a view taken along arrows IV-IV in FIG. 2, FIG. 5 is a sectional view taken along arrows V-V in FIG. FIG.
[0030]
This manufacturing apparatus uses a specially shaped mold 10, holds a ceramic substrate K (see FIG. 3 and FIG. 6B) inside the mold 10, and brings a metal melt into contact therewith, thereby making a metal -Manufacturing ceramic composite members. As shown in FIG. 1, this manufacturing apparatus includes an atmosphere replacement unit (atmosphere replacement unit) 1 that adjusts the atmosphere in the mold 10 to an inert gas atmosphere condition with an oxygen concentration of 1% or less, and the atmosphere replacement unit 1 to change the atmosphere. The preheating part 2 for preheating the mold 10 after replacement, and the temperature in the mold 10 preheated by the preheating part 2 are maintained at the pouring temperature, and in this state, the molten metal is put into the mold 10 on the surface of the ceramic member. A pouring part 3 for pouring so that the molten metal moves from one side to the other side in contact with each other and fills the inside of the mold sequentially, and the temperature in the mold 10 poured by the pouring part 3 The molten metal starts to solidify and is cooled to a joining temperature at which the joining action is exerted to join the metal to the ceramic, and the slow cooling part 5 that slowly cools the mold 10.
[0031]
These atmosphere replacement part 1, preheating part 2, pouring part 3, cooling joint part 4, and slow cooling part 5 are arranged in series in the horizontal direction, and between the atmosphere replacement part 1 and preheating part 2, the pouring part Shielding shutters 6A, 6B, and 6C are provided between the cooling unit 4 and the cooling unit 4 and between the cooling unit 4 and the slow cooling unit 5. Further, heaters 8A, 8B and 8C as heating means and temperature control means are provided on the side walls of the preheating part 2, the pouring part 3 and the cooling part 4 so that the temperature of the mold 10 accommodated in the room can be appropriately controlled. It is like that. In particular, the cooling joint 5 is provided with a water cooling jacket 9 as a cooling means so that the mold 10 can be cooled from the bottom. In addition, in the pouring part 3 of FIG. 1, what is shown by the code | symbol 21 attached to the casting_mold | template 10 is a linear motor, 22 is a graphite piston. These correspond to pouring means.
[0032]
Next, the mold 10 made of graphite will be described.
As shown in FIGS. 2 and 3, the mold 10 used here is a combination of three front and back mold plates 10A and 10A and a central mold plate 10B, which are combined to form four circuit boards (metals at a time). -Ceramic composite material). 4 shows the shape of the inner wall surface of the front and back mold plates 10A, and FIG. 5 shows the shape of both wall surfaces of the central mold plate 10B.
[0033]
These mold plates 10A and 10B have recesses 11A, 11B, 13A, 13B, 14A and 14B having a predetermined shape. When combined as the mold 10, the injection plate fixing portion 11 as a molten metal inlet, the molten metal An introduction passage 13 and a joint 14 are formed. The molten metal injection cylinder fixing portion 11 is disposed at the center of the mold 10, and the molten metal introduction passage 13 is expanded in the horizontal direction so as to branch from the lower portion thereof, and each joint portion 14 is communicated with the tip of each molten metal introduction passage 13. Is provided. The space as the joint portion 14 is formed on both front and back surfaces of the central mold plate 10B, and two spaces are formed symmetrically with the molten metal injection tube fixing portion 11 interposed therebetween. Therefore, there are four in total.
[0034]
Further, the mold 10 constituted by the three mold plates 10A, 10A, and 10B is formed with a narrow portion 12 that is located at the boundary between the molten metal injection cylinder fixing portion 11 and the molten metal introduction passage 13 and communicates the two. A ceramic member fixing recess 16 is formed in such a manner that the central region overlaps with the joint portion 14, and a gas vent hole 15 is formed so as to communicate with the upper portion of the joint portion 14. As shown in FIG. 6B, the relationship between the ceramic member fixing recess 16 and the joint 14 is such that when the mold 10 is closed with the ceramic member K fitted in the ceramic member fixing recess 16, The relationship is such that a predetermined gap 29 can be secured between the inner wall surface and the ceramic member K.
[0035]
Further, the narrow portion 12 is a portion for removing the oxide film on the surface of the molten metal injected from the molten metal injection cylinder fixing portion (corresponding to the molten metal introduction port) 11 and has a diameter that does not allow the passage of the oxide film (for example, 1 mm or less, preferably 0.8 mm or less). The molten metal from which the oxide film has been removed by the narrow portion 12 enters a vertical space of the molten metal introduction passage 13 and is then introduced into the bottom of the joint portion 14 through the horizontal space of the molten metal introduction passage 13. It moves upward from the bottom of the part 14 and contacts the surface of the ceramic member K held in the ceramic member fixing recess 16 during that time. Therefore, after the molten metal is injected into the molten metal injection cylinder fixing portion 11, the molten metal path is configured so that the molten metal once falls downward and then contacts the ceramic member K while moving upward.
[0036]
The outer peripheral portions of the mold plates 10A, 10A, and 10B are provided with concave and convex portions 19A and 19B that are fitted together to position the mold plates 10A, 10A, and 10B.
[0037]
Next, a method for producing a target composite member using the mold 10 and the manufacturing apparatus will be described.
Here, four alumina ceramic substrates of 62 mm × 112 mm × 0.635 mm are prepared as ceramic members K, and these substrates K are used for fixing the ceramic members of the front and back mold plates 10A and 10B as shown in FIG. The integrated mold 10 is made by fitting into the recess 16 and combining the front and back mold plates 10A and 10A with the central mold plate 10B. Next, the mold 10 is placed in the atmosphere replacement unit 1 and nitrogen gas is allowed to flow into the furnace of the atmosphere replacement unit 1 so that the oxygen concentration in the mold 10 is 1% or less, preferably 0 to 500 ppm (atmosphere Replacement step).
[0038]
Next, the mold 10 is moved to the preheating unit 2, and the temperature of the mold 10 is raised from room temperature to 800 ° C. in 1 hour by the heater 8A in the preheating unit 2 (preheating step). In this case, the temperature must be increased so that the ceramic member K in the mold 10 does not break.
[0039]
Next, the preheated mold 10 is moved to the injection section 3, and the graphite piston 22 and the linear motor 11 are set in the molten metal injection cylinder fixing section 11 at the upper part of the mold 10. Then, with the molten aluminum (metal melt) injected into the mold 10, the linear piston 21 pressurizes the graphite piston 22 to push the molten aluminum into the mold 10 (the pushing force is 70 kg MAX) and passes through the narrow portion 12. By doing so, only the pure aluminum molten metal after breaking the aluminum surface oxidation is supplied to the molten metal introducing passage 13 below the narrow portion 12. It is preferable to inject the molten aluminum into the mold 1 so that the molten aluminum moves on the ceramic substrate at a speed of 1000 mm / min or less.
[0040]
As described above, when the molten aluminum is pushed into the molten metal introduction passage 13, the molten aluminum is introduced into the bottom of the joint portion 14 from the molten metal introduction passage 13 and is fixed to both sides of the ceramic member positioning recess 16. To reach the upper end (molten reservoir) of the joint 14 (a pouring process). When a part of them escapes from the vent hole 15, the operation of the linear motor 21 is stopped.
[0041]
During the pouring step, the furnace temperature of the pouring part 3 is adjusted to 700 to 850 ° C. with the heater 8B. This is because, since the melting point of aluminum is 660 ° C., the flowability of hot water becomes poor at 700 ° C. or lower, and conversely, when it is 850 ° C. or higher, it reacts with the mold release material and the mold separation becomes worse.
[0042]
When the pouring step is completed, the mold 10 is moved to the cooling joint 4, and the cooling joint 4 is cooled by the lower water-cooling jacket 9 while being heated by the heaters 8 </ b> C on both walls. While applying a temperature gradient of 3 to 5 ° C. per 1 cm in the height direction, it is gradually cooled to 600 ° C. over 30 minutes to join aluminum to the ceramic substrate (joining step).
[0043]
Next, after the mold 10 is taken out to the slow cooling part 5 and gradually annealed to near room temperature (slow cooling process), the mold 10 is taken out, and four aluminum-alumina ceramic composite members are taken out from the mold 10 to perform the work. Complete.
[0044]
The aluminum-alumina ceramic composite member thus obtained exhibited a uniform surface free from shrinkage cavities on the aluminum surface.
[0045]
In addition, even when the same treatment was performed using an aluminum nitride member or a silicon nitride member as the ceramic member, a composite member having a uniform surface without shrinkage cavities was obtained.
[0046]
【The invention's effect】
As described above, according to the present invention, the direct bonding force at the interface between the ceramic and the metal can be extremely strengthened, and a composite substrate free from shrinkage can be manufactured with a high yield. Therefore, for example, when joining thin metal plates as circuit surfaces and thin metal plates as heat dissipation surfaces to both surfaces of a ceramic substrate, and joining thin metal plates with different thicknesses to both surfaces, the accuracy of the mold is reduced. By making it appropriate, it is possible to easily join metal thin plates with high precision and uniform thickness. In addition, by setting the mold to an appropriate temperature in each process such as the preheating process, the pouring process, and the joining process, it is possible to avoid applying excessive thermal stress to the ceramic member, and there is a risk of damage due to thermal stress. It can be lost. Further, if a narrow portion for removing the oxide film is provided inside the mold and only the pure molten metal from which the oxide film has been removed is supplied to the joint, a stronger bonding force can be obtained. Therefore, a wide variety of metal-ceramic composite members having excellent bonding characteristics can be manufactured at low cost.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a configuration of a main part of a metal-ceramic composite member manufacturing apparatus according to the present invention.
FIG. 2 is a schematic perspective view of a mold used in the metal-ceramic composite member manufacturing apparatus of the present invention.
3 is an exploded plan view of the mold as seen from the direction of arrows III-III in FIG.
4 is a view taken along arrow IV-IV in FIG. 2;
5 is a VV arrow view of FIG. 2;
6A is a cross-sectional view taken along the line VIa-VIa in FIG. 2, and FIG. 6B is a cross-sectional view taken along the line VIb-VIb in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Atmosphere substitution part 2 Preheating part 3 Injection | pouring part 4 Cooling part 5 Slow cooling part 8A, 8B, 8C Heater (heating means, temperature control means)
9 Water cooling jacket (cooling means)
DESCRIPTION OF SYMBOLS 10 Mold 11 Molten inlet 12 Narrow part 13 Metal molten metal path 14 Joint part 15 Gas vent hole K Ceramic member

Claims (5)

A molten metal inlet for introducing a molten metal into the mold, and a joint for holding a ceramic member and securing a predetermined gap between the surface of the ceramic member and the inner wall of the mold, and from the molten metal inlet Using a mold having a narrow portion for removing the oxide film formed on the surface of the molten metal in the middle of the path leading to the joint,
The ceramic member is held in the mold, and a molten metal of the metal to be joined is poured into the mold so as to be in contact with the surface of the ceramic member to be cooled and solidified, whereby the interface between the ceramic and the metal is obtained. In a method for producing a metal-ceramic composite member in which a metal is bonded to the surface of a ceramic member by direct bonding force at
A mold atmosphere replacement step of replacing the atmosphere in the mold with the ceramic member held in the mold to reduce the oxygen concentration to a predetermined value or less;
A preheating step for preheating the mold after the step, and a temperature in the mold is maintained at a pouring temperature after the step, and the molten metal after the oxide film is removed by the narrow portion is supplied to the joint portion. time, said the molten metal is brought into contact with the ceramic member while moving upward, and poured as we meet in the template, the molten metal within the template, meets the said template, said A pouring process of pouring so as to reach the molten metal reservoir at the upper end of the joint where the ceramic member and the metal are joined;
After the step, the temperature in the mold is lowered to a bonding temperature at which the molten metal starts to solidify and exhibits a bonding action, and the metal is bonded to the surface of the ceramic member. A lowering operation, a joining step in which the temperature is lowered stepwise from the bottom of the mold toward the top;
And a slow cooling step of slowly cooling the mold after the step,
In the pouring step, when the molten metal is brought into contact with the ceramic member while being moved upward, the molten metal is moved on the ceramic member at a speed of 1000 mm / min or less, and the metal is A method for producing a metal-ceramic composite member, characterized by being aluminum or an alloy containing aluminum as a main component.   2. The method for producing a metal-ceramic composite member according to claim 1, wherein in the template atmosphere replacement step, the oxygen concentration is set to 1% or less.   The method for producing a metal-ceramic composite member according to claim 2, wherein the pouring temperature is set to 700 to 800 ° C in the pouring step.   The method for producing a metal-ceramic composite member according to claim 2 or 3, wherein in the joining step, a joining temperature is set to 550 to 750 ° C.   5. The metal-ceramic composite member according to claim 1, wherein the ceramic member is one of aluminum oxide, nitride, carbide, silicon oxide, nitride, and carbide. Manufacturing method.

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