JPH1160343A - Production of joined body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a joined body consisting of ceramics and metallic sheets which has high durability to thermal shock and thermal histeresis such as heat cycles, etc., and are adequate for the manufacture of powder module circuits at a good yield with enhanced productivity. SOLUTION: One or plural pieces of the laminates formed by laminating the ceramic sheets and the metallic sheets with or without the intervention of joining materials are stacked in a longitudinal direction or are pressed and arrayed in a traverse direction with or without the intervention of spacers and are arranged in a furnace. The one or >=2 flanks of the metallic sheets of the laminates are brought into contact with a heating member and are heated. The heating member is a jig comprising a frame 3, a pressure plate 4 and a pressing means 5 for the pressure plate 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a joined body composed of a ceramic plate and a metal plate, which is particularly suitable for manufacturing a power module substrate.

[0002] In recent years, power modules such as high-power and high-efficiency inverters have been transitioning with the advancement of the performance of industrial equipment such as robots and motors, and the heat generated from semiconductor elements has been increasing steadily. In order to efficiently dissipate this heat, various methods have conventionally been used for power module substrates. In particular, since ceramic substrates with good heat conduction have become available recently, a copper plate such as copper is bonded on the substrate, and after forming a circuit, the substrate is subjected to a treatment such as plating or plating, and then a semiconductor element is mounted on the circuit surface. Is installed. In this case, there is a structure in which a metal radiating plate for attaching a radiating fin is joined to the opposite side of the circuit.

[0003] Such modules were initially used for simple machine tools, but have been used in welding machines, train drives and electric vehicles in recent years. In addition, the environment in which the power module is used is becoming severer, and requirements for quality are becoming more severe. Therefore, development of mass production technology for power module substrates with stable quality is awaited. For this requirement, the joining of the ceramic plate and the metal plate is an important point.

There are various methods for joining a metal and a ceramic, but from the viewpoint of manufacturing a circuit board, Mo-Mn
Method, active metal brazing method, copper sulfide method, DBC method, copper metallization method and the like. Of these, for joining copper and a ceramic substrate, an active metal brazing method is used to form a joined body by interposing a brazing filler metal containing an active metal between the two to form a joined body (see, for example, JP-A-60-177634). And a DBC method in which a ceramic substrate and a copper plate whose surfaces are oxidized are heated and joined at a temperature lower than the melting point of copper and higher than the eutectic temperature of Cu-O (for example, JP-A-56-163093).

In the active metal brazing method, (a) the processing temperature for obtaining the joined body is lower than that of the DBC method, so that the residual thermal stress caused by the difference in thermal expansion between the ceramic substrate and copper is small. Since the brazing filler metal containing the active metal is a ductile metal, there are advantages such as high durability against heat shock and heat cycle.

[0006] In the DBC method, it is important to control its own unique bonding mechanism, especially temperature control. On the other hand, even in the active metal brazing method, in order to satisfy the characteristics of the power module substrate required at present, the brittleness of the ceramic due to excessive penetration of the active metal into the ceramic side and the formation of the brazing metal component into the metal plate. It is necessary to prevent the hardening of the metal due to excessive diffusion of the metal, and this requires bonding at a temperature range difference of about 10 ° C.

[0007]

However, in the case of the conventional active metal brazing method, it is necessary to maintain a non-oxidizing atmosphere such as in a vacuum, so that in order to improve mass productivity, it is necessary to rely on a batch type furnace. However, since a large amount of workpieces are charged at one time, there are many deficiencies in temperature control, and the quality tends to vary widely.

The inventors of the present invention have made intensive studies in view of the above, and as a result, in a laminate comprising a ceramic plate and a metal plate, if the side of the metal plate is brought into contact with a heating member and heated, the laminate is formed. Can precisely control the amount of heat applied to the product, resulting in less variation in the quality of the joined body, and improved yield and productivity.
The present invention has been completed.

[0009]

That is, the present invention relates to a method of forming one or a plurality of laminated bodies obtained by laminating a ceramic plate and a metal plate with or without a bonding material therebetween, with or without a spacer. Ceramics characterized in that they are stacked in a vertical direction or arranged in a furnace by being pressed and arranged in a horizontal direction and placed in a furnace, and heated by bringing one or more side surfaces of the metal plate of the laminate into contact with a heating member. The present invention relates to a method for producing a joined body composed of a plate and a metal plate, and more particularly to a method for producing a joined body characterized in that a heating member has a heater function.

[0010] The present invention also relates to the heating member (10).
Is a jig composed of a frame (3), a pressing plate (4), and a pressing means (5) for the pressing plate. In the method for manufacturing a joined body, the ceramic is aluminum nitride, the metal is copper or a copper alloy, the joining material is a brazing material containing an active metal, and the heating member is a carbon jig.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

Examples of the ceramic plate used in the present invention include alumina, silicon nitride, and aluminum nitride. Aluminum nitride having high thermal conductivity is particularly desirable. The aluminum nitride plate is obtained by adding about 2 to 5% by weight of a sintering aid such as a rare earth oxide (for example, yttria) or an alkaline earth oxide (for example, calcia) to aluminum nitride powder and firing after molding. Can be manufactured by The thickness of the ceramic plate is preferably about 0.5 to 1.0 mm, because if it is too thick, the thermal resistance increases, and if it is too thin, the durability is lost.

On the other hand, the metal plate serving as a metal circuit and / or a metal radiator plate includes copper, aluminum, tungsten,
Molybdenum or the like is used, but copper or a copper alloy is generally used. Regarding the thickness of the metal plate, in the case of a metal plate for forming a metal circuit, the current density tends to increase in recent years.
The thickness is preferably greater than 3 mm, and in the case of a metal plate for forming a metal heat sink, it is preferably 0.2 mm or less.

The method of joining the ceramic plate and the metal plate may be the DBC method or the active metal brazing method. DBC
Although it is not necessary to use a bonding material in the method, the active metal brazing method uses silver and copper as the main components as the bonding material, and the active metal as a sub-component to ensure the wettability with the ceramic plate during melting Things are used. The active metal component reacts with the ceramic plate to generate oxides and nitrides, and these products strengthen the bond between the brazing material and the ceramic plate. Specific examples of active metals include titanium,
Zirconium, hafnium, niobium, tantalum, vanadium and their compounds. These percentages are
Total amount of 80 to 97 parts by weight of silver and 20 to 3 parts by weight of copper 100
1 to 7 parts by weight of active metal per part by weight.

In the present invention, one or a plurality of laminates obtained by laminating a ceramic plate and a metal plate with or without a bonding material are stacked vertically or arranged in a state of being pressed in the horizontal direction. And place in a furnace to heat. At this time, in the case of stacking or arranging such that the metal plates of the laminate are in contact with each other, depending on the type of the metal plates, the metal plates may be fused at a joining temperature, and therefore, a material that does not react with the metal plates. It is desirable to arrange a spacer made of a metal plate or a spacer made of a metal plate whose surface is coated with a material that does not react with the metal plate.

In the present invention, as described above, the laminates are stacked in the vertical direction or arranged in a furnace while being pressed in the horizontal direction, and are arranged in the furnace. This is preferable because the arrangement is easy and the arrangement state is stable. When arranging horizontally,
Pressing is performed in the horizontal direction in order to maintain the contact between the ceramic plate and the metal plate. However, in the case of stacking in the vertical direction, the pressing is not particularly necessary because the contact is maintained by its own weight. The pressing is preferably performed by the jig shown in FIG.

An important point in the present invention is that when heating the above-mentioned laminate, one or more side surfaces of the metal plate of the laminate are heated by contacting with a heating member. As a result, heat is uniformly and smoothly transmitted from the heating member to the metal plate,
It is possible to adjust the amount of heat applied to each of the laminates in a more severe range than before. As a result, the ceramic plate and the metal plate are easily joined, and the temperature distribution between the laminates is reduced, so that the yield is improved.

It is preferable that the heating member itself has a heater function, but it does not have to be.
Any material may be used as long as the material or the heat capacity is such that heat generated from the heater provided in the furnace is quickly transmitted to the metal plate of the laminate. As such a material, carbon is convenient, but a metal such as copper having good thermal conductivity may be used. However, a material that reacts with and fuses with the metal plate of the laminate is inappropriate.

The heating member suitable for the present invention is, as shown in FIG. 1, a jig composed of a frame (3), a pressing plate (4), and pressing means (5) for the pressing plate. is there. FIG.
FIG. 3 is a schematic side view showing a state in which a laminate (1) is arranged on a jig as a heating member. The laminate (1) is arranged via a spacer (2) between the left end plate of the frame (3) and the push plate (4), and the side surface of the metal plate of the laminate is a bottom plate of the frame (3). And that the entire laminate is pressed by the screw-type pressing means (5). In this case, it is preferable that the entire jig has a heater function such as carbon. The pressing means is preferably of a screw type, but may be of another type such as a spring type as long as it can fix the laminate.

In the present invention, another advantage of employing the pressing means is that the wettability between the metal plate or the ceramic plate and the active metal brazing material is adjusted by changing the pressing force for fixing the laminate. Is made possible. As a result, it is possible to join even at a temperature where joining was not possible by the conventional method of stacking the stacked bodies in the vertical direction and placing the weight on the top. Another problem is that the problem of misalignment caused by a difference in thermal expansion between the metal plate and the ceramic plate can be avoided. Furthermore, the number of heat treatments of the laminated body was at most about 20 per unit in the conventional stacking method, but this can be increased to about 80, which is a significant improvement in productivity. .

[0021]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

Examples 1 to 3 Comparative Example 1 96 parts by weight of aluminum nitride powder, 4 parts by weight of a sintering aid (yttria) and 2 parts by weight of a surface treating agent (oleic acid) were premixed in a vibration mill, and then organically bonded. 8 parts by weight of a material (ethyl cellulose), 3 parts by weight of a plasticizer (glycerin triolate) and 12 parts by weight of water were mixed and mixed by a mixer, and the mixture was extruded. Next, the extruded body was heated at 120 ° C. × 5.
After drying for 5 minutes, degreasing was performed in the air at 480 ° C. for 10 hours, and calcination was performed at 1860 ° C. × 2 hours. The obtained sintered body was processed into a size of 60 mm × 36 mm × 0.65 mm, and the surface was honed to produce an aluminum nitride plate.

90 parts by weight of silver powder, 10 parts by weight of copper powder, 3 parts by weight of zirconium powder, 3 parts by weight of titanium powder, 15 parts by weight of terpineol and an organic binder (a toluene solution of polyisobutyl methacrylate) were solidified as a whole. On the other hand, 5% by weight was added and kneaded well to prepare a brazing filler metal paste. This brazing material paste was applied to both surfaces of the aluminum nitride plate by screen printing over the entire surface. The coating amount (after drying) at that time was 9 mg / cm ² .

Next, as shown in FIG. 2, a 60 mm × 36 mm aluminum nitride plate [ceramic plate (8)] coated with a brazing material paste [joining material (9)] is applied.
A copper plate [metal plate (7)] of × 0.3 mm and a copper plate [metal plate (7)] of 60 mm × 36 mm × 0.15 mm on the opposite surface were placed in contact with each other to form a laminate (1). .

In the first embodiment, 20 pieces of the above-mentioned laminates are stacked as shown in FIG. 3 and a weight member (11) is placed thereon. Then, the side surface of the metal plate (7) of the laminate is attached to a heating member (10) made of carbon. ), And the 18 units thereof are uniformly arranged via a shelf plate (6) in an external heating type furnace in which the inside of the furnace is divided into upper and lower two rooms, and the degree of vacuum is 1 × 10 ⁻⁵ Torr or less. After holding at various temperatures shown in Table 1 for 30 minutes under vacuum, the bonded body was manufactured by cooling at a temperature lowering rate of 2 ° C./min. The heating member is
It was screwed and fixed to a shelf plate in the furnace via a support (not shown).

In the second embodiment, as shown in FIG. 4, twenty of the above-mentioned laminates are arranged in a horizontal direction, and both ends thereof are supported by a carbon support member (not shown). ) Was brought into contact with a heating member (10) made of carbon, and its 18 units were placed in a furnace, heated and cooled to produce a joined body. The heating member was fixed to the shelf plate in the furnace by screwing via a support (not shown).

In the third embodiment, as shown in FIG. 1, 80 pieces of the above-mentioned laminates are housed in a jig which is a heating member (10).
The eight units were placed in a furnace, heated and cooled to produce a joined body.

In Comparative Example 1, a joined body was manufactured in the same manner as in Example 1, except that heating and cooling were performed without using a heating member.

A UV curing type etching resist is applied on the copper plate of the joined body obtained above by screen printing, and then an etching process is performed using a cupric chloride solution to dissolve and remove unnecessary portions of the copper plate and further etching. 5 resist
Exfoliated with a sodium hydroxide solution. In the joined body after this etching process, there is a residual unnecessary brazing material or a reaction product between the active metal component and the aluminum nitride plate between the copper circuit patterns.
To remove it, it was immersed in a 10% ammonium fluoride solution at a temperature of 60 ° C. for 10 minutes.

With respect to the aluminum nitride substrate manufactured through these series of processes and having a copper circuit on one surface and a heat-dissipating copper plate on the other surface, one sample was extracted from each of the 18 units, and a sample was taken from the heat-dissipating copper plate side. The three-point bending strength when pressed is as follows: span 30 mm, crosshead speed 0.5
It was measured under the condition of mm / min. In addition, a heat cycle resistance test was performed at -40 ° C for 30 minutes in the air, and then at 25 ° C for 1 hour.
Leave for 0 minutes, hold at 125 ° C x 30 minutes, then 25 ° C x 1
Leaving for 0 minute was regarded as one cycle, and the number of heat cycles at which the copper circuit or the heat radiating copper plate started to peel was measured. Table 1 shows the results of 18 test pieces.

[0031]

[Table 1]

[0032]

According to the present invention, a joined body composed of a ceramic and a metal plate, which has high durability against thermal shocks and heat histories such as a heat cycle and is suitable for manufacturing a power joule substrate, has a good yield, and has a high productivity. Can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a state in which laminates are arranged on a jig as a heating member.

FIG. 2 is a schematic side view of a laminate.

FIG. 3 is a schematic front view showing a state in which the laminates are stacked in a vertical direction, and a side surface of a metal plate of the laminate is in contact with a heating member.

FIG. 4 is a schematic side view showing a state in which the laminate is arranged in a horizontal direction, and a side surface of a metal plate of the laminate is in contact with a heating member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joined body 2 Spacer 3 Frame 4 Push plate 5 Pressing means 6 Shelf plate 7 Metal plate 8 Ceramic plate 9 Joining material 10 Heating member 11 Weight material

Claims (4)

[Claims] 1. One or a plurality of laminates obtained by laminating a ceramic plate and a metal plate with or without a bonding material are stacked vertically or horizontally with or without a spacer. Arranged in the furnace by pressing in the direction,
A method for manufacturing a joined body comprising a ceramic plate and a metal plate, wherein one or two or more side surfaces of the metal plate of the laminate are heated by being brought into contact with a heating member. 2. The method according to claim 1, wherein the heating member has a heater function. 3. The heating member (10) is a jig comprising a frame (3), a pressing plate (4), and pressing means (5) for the pressing plate. 3. The method for producing a joined body according to 1 or 2. 4. The method according to claim 3, wherein the ceramic is aluminum nitride, the metal is copper or a copper alloy, the joining material is a brazing material containing an active metal, and the heating member is a carbon jig.
A method for producing the joined body according to the above.