KR101890396B1 - Manufacturing method of tungsten-copper clad alloy and clad alloy using the same - Google Patents

Abstract

A method of manufacturing a tungsten-copper clad alloy according to the present invention comprises the steps of: a) pressing a tungsten metal powder having an average particle size of 10 μm or less (excluding 0) to produce a tungsten compact; b) impregnating the tungsten compact with copper to produce a tungsten-copper alloy; And c) hot-pressing an oxygen free copper on at least one side of the tungsten-copper alloy to diffusion bond the tungsten-copper alloy and the oxygen free copper.

Description

Description: TECHNICAL FIELD The present invention relates to a tungsten-copper clad alloy and a clad alloy using the tungsten-copper clad alloy,

The present invention relates to a method for producing a tungsten-copper clad alloy and a clad alloy using the same.

Generally, metals are metal bonded by free electrons. The relationship between the force acting on atoms and the distance of atoms is explained as follows. When two atoms are very far apart, mutual attraction acting on these two atoms is close to zero, And becomes maximum at a distance of 1.5 times the inter-track distance. As the atoms approach each other, the attraction and repulsion become equal in size and become energetically stable.

Diffusion bonding utilizes this principle, in which the two elements are brought into a manpower zone in a solid state by means of heating and pressing so that they are metal-bonded. In practice, to achieve this state, the metal surface must be completely clean and smooth

The general diffusion bonding process can be divided into the following three processes.

(1) High-temperature creep deformation process: By heating and pressing, plastic deformation similar to high-temperature creep deformation occurs, various kinds of surface coatings are destroyed, and a local pure surface appears. This phenomenon is accompanied by an increase in the area in contact with the pure metal as the time increases. At the same time, diffusion movement occurs between the parent materials.

(2) Grain migration and disappearance process of voids: The voids that are not elongated and remain in the non-contact area are spheroidized to reduce the interfacial energy, that is, the surface tension. As the bonding progresses, the voids gradually disappear due to the intergranular diffusion, and the grain boundary shifts to shift the energy of the line-shaped grain to a more stable state.

(3) Disappearance process of voids by solid diffusion: Grain shifts and voids are almost lost by shedding. In this process, grain growth or recrystallization often occurs. Various oxide coatings and surface coatings are generally employed or finely dispersed in the base material.

However, unlike ordinary diffusion bonding, interdiffusion bonding between dissimilar metals is complicated because intermetallic compound (or precipitate) is formed near the bonding interface or grain boundary.

Here, examples of dissimilar metals include W-Cu, Mo-Cu, and Cu / Mo / Cu (CMC). Cu is excellent in thermal conductivity, but has a large difference in thermal expansion coefficient from Si (silicon), GaAs (gallium arsenide), and Al ₂ O ₃ (alumina), which are semiconductor element substrates. Therefore, Cu is a small IC with low heat dissipation and its use is limited by soft soldering such as low melting point solder.

W and Mo are close to the thermal expansion coefficient of Si of the semiconductor element, but are not as excellent in thermal conductivity. Therefore, this W or Mo is used only for a large-sized IC which can form a wide heat-releasing surface as a substrate on which Si is mounted.

Thus, W-Cu, Mo-Cu composite alloys and clad type CMCs as composites utilizing the advantages of each of these single metal materials. And is being used for medium or large ICs.

Among these, W, Mo, and W-Cu or Mo-Cu containing a large amount of W, Cu, and Mo are high in weight and are not suitable for demanding reduction in weight. Also, since they have rigidity, plastic working is difficult.

On the other hand, Cu and CMC can be plastic-worked by the ductility of Cu. As described above, Cu has a large difference in thermal expansion coefficient from that of a semiconductor device and a ceramic. Therefore, it is easy to cause defects at the bonding interface with the counter material due to the influence of thermal stress during bonding and operation, It is easy to cause damage such as cracks.

In addition, due to such an intermetallic compound, voids are generated as a stress concentration source in the hot pressing process, and these voids eventually grow into cracks and cause grain boundary fracture.

Korean Patent No. 10-1612346

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method of manufacturing a tungsten-copper clad alloy having excellent mechanical strength and thermal conductivity by solving the unfavorable synthesis of an interface during dissimilar metal interdiffusion bonding.

The present invention also provides a clad alloy using the method for producing a tungsten-copper clad alloy.

The present invention also provides a heat sink using a clad alloy.

On the other hand, other unspecified purposes of the present invention will be further considered within the scope of the following detailed description and easily deduced from the effects thereof.

According to an aspect of the present invention, there is provided a method of manufacturing a tungsten-copper clad alloy, comprising: a) preparing a tungsten compact by pressurizing a tungsten metal powder having an average particle size of 10 μm or less (excluding 0); b) impregnating the tungsten compact with copper to produce a tungsten-copper alloy; And c) hot-pressing an oxygen free copper on at least one side of the tungsten-copper alloy to diffusion bond the tungsten-copper alloy and the oxygen free copper.

In the method for manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the tungsten metal powder may be pressurized at 1 to 30 Ton / cm 2 in step a).

 In the method for manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, in the step b), the copper may be infiltrated at 1100 to 1600 캜 in a reducing atmosphere.

In the method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, in the step c), the hot pressing may be performed at a temperature lower than the melting point of copper.

In the method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the hot pressing may be performed at 850 to 1050 ° C.

In the method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, in the step c), the hot pressing may be performed at a pressure of 1 to 100 Ton / cm 2.

In the method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the tungsten-copper alloy may contain 5 to 30% by weight of copper.

In the method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the tungsten metal powder may include bimodal tungsten metal particles having different average particle diameters.

In the method for manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the tungsten metal particles may satisfy the following relational expressions 1 to 3:

[Relation 1]

1.5 占 퐉? D1? 3.5 占 퐉

[Relation 2]

4.0 占 퐉? D2? 6.0 占 퐉

[Relation 3]

0.5? H1 / h2? 1.5

(In the above relational expressions 1 to 3, D1 is the center size of the first peak having the smallest center size, with respect to the center size of the peak in the size distribution of the tungsten metal powder, D2 is the center size of the peak, H1 is the center height of the first peak, and h2 is the center height of the second peak.

The present invention also includes a clad alloy formed by the above-described production method.

A tungsten-copper clad alloy according to an embodiment of the present invention includes a first layer made of a tungsten-copper alloy; And a second layer of oxygen-free copper formed on one or both sides of the first layer.

In the tungsten-copper clad alloy according to an embodiment of the present invention, the clad alloy may satisfy the following relationship:

[Relation 4]

1.1? T1 / T2? 2.1

(In the above relational expression 4, T1 is the thickness of the first layer made of the tungsten-copper alloy, and T2 is the thickness of the second layer made of the oxygen-free copper.)

The present invention also includes a heat sink including the above-described clad alloy.

A method of manufacturing a tungsten-copper clad alloy according to the present invention is a method of manufacturing a tungsten-copper clad alloy capable of ensuring thermal characteristics such as thermal conductivity, preventing physical deformation occurring during a manufacturing process, Can be provided.

The method of manufacturing a tungsten-copper clad alloy according to the present invention solves the problem of plating and peeling off of a chip mounting surface which occurs when a conventional single tungsten-copper alloy is applied to a semiconductor package, .

On the other hand, even if the effects are not explicitly mentioned here, the effect described in the following specification, which is expected by the technical features of the present invention, and its potential effects are treated as described in the specification of the present invention.

1 is a SEM photograph of a CMC alloy manufactured using diffusion bonding.
FIG. 2 is a process flow chart showing a method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention.
3 is a cross-sectional SEM photograph of the tungsten-copper alloy according to Example 1 of the present invention and the analysis result of the EDS component.
Fig. 4 shows SEM photographs and EDS component analysis results of the tungsten-copper alloy according to Example 2 of the present invention.
5 shows SEM photographs and EDS component analysis results of a tungsten-copper alloy according to Example 3 of the present invention.
6 is a SEM photograph of a section of the tungsten-copper clad alloy produced in Example 2 of the present invention.

Hereinafter, the present invention will be described in detail. The following embodiments and drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. In addition, unless otherwise defined in the technical and scientific terms used herein, unless otherwise defined, the meaning of what is commonly understood by one of ordinary skill in the art to which this invention belongs is as follows, A description of known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

As used herein, the term "alloy" may refer to a mixture of two or more metals at a microscopic level. For example, the structure of the alloy may include a solid solution, an intermetallic compound, or a mixture thereof.

The heat sink applied to the semiconductor package is manufactured by bonding substrates by brazing, diffusion bonding, etc., and examples of the heat sink include CMC (Cu-Mo-Cu), CPC (Cu-MoCu- S-CMC (Super CMC), and the like.

1 is a SEM photograph of a CMC alloy manufactured using diffusion bonding. Referring to FIG. 1, after the diffusion bonding, the CMC alloy 3 may include delamination, crack, etc. between the Cu layer 1 and the Mo layer 2. Defects at interfaces such as peeling and cracks are a factor for lowering thermal conductivity and mechanical strength.

In order to solve such a problem, the applicant of the present invention has found that, when copper is manufactured by diffusion bonding of copper to a tungsten-copper heat sink, thermal characteristics such as thermal conductivity are assured, physical deformation occurring during the manufacturing process can be prevented, Copper clad alloy which can provide a high surface hardness.

In particular, in the present invention, when the average particle diameter of the tungsten metal powder is 10 μm or less and the tungsten metal powder has a bimodal distribution with different average particle diameters, it exhibits sufficient thermal conductivity and mechanical strength for the purpose of the present invention The present invention has been completed. In the present invention, it is observed that when the average particle size of the tungsten metal powder is more than 10 탆, defects are still generated at the interface, and thermal conductivity and mechanical strength are remarkably lowered.

In order to solve the above problems, a method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention includes the steps of: a) pressing a tungsten metal powder having an average particle size of 10 μm or less (excluding 0) to produce a tungsten compact; b) impregnating the tungsten compact with copper to produce a tungsten-copper alloy; And c) hot-pressing an oxygen free copper on at least one side of the tungsten-copper alloy to diffusion bond the tungsten-copper alloy and the oxygen free copper.

FIG. 2 is a process flow chart showing a method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention. 2, the method for manufacturing a tungsten-copper clad alloy according to the present invention includes a step (S100) of forming a tungsten compact, a copper infiltration step (S200), and a diffusion bonding step (S300) of tungsten copper and oxygen- can do.

The step (S100) of producing a tungsten compact may mean mixing the tungsten metal powder and the binder, and putting the mixed mixture into the molder to produce a tungsten compact.

In the method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the binder may be selected from at least one or more of a thermosetting resin, a thermoplastic resin, and a photocurable resin.

As a specific and non-limiting example, the thermosetting resin may be a polyamide, a polyether, a polyimide, a polysulfone, an epoxy resin, an unsaturated polyester resin, a phenol resin, or the like.

As another specific and non-limiting example, the thermoplastic resin may be a nylon resin, a polyethylene resin, a polyamide resin, a polyester resin, a polycarbonate resin, a polyarylate resin, a cycloolefin resin or the like.

As a specific and non-limiting example, the photo-curable resin may be a radical curable resin (an acrylic oligomer, an unsaturated polyester, an ester polymer such as an acrylic monomer, a polyester acrylate, a urethane acrylate, or an epoxy acrylate) Cationic curing resin (epoxy resin, oxetane resin, vinyl ether resin), and the like.

Meanwhile, in the method for manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the binder may be about 0.1 to 10 parts by weight based on 100 parts by weight of the tungsten metal powder, but the present invention is not limited thereto . When the weight range of the binder is satisfied, the shape-retaining ability of the tungsten mold according to the present invention can be improved. Copper can be formed in the tungsten mold at a predetermined amount during the copper infiltration step (S200).

Further, in the method for manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the tungsten metal powder may have a bimodal distribution with an average particle diameter of 10 μm or less and different from each other. If the average particle size of the tungsten metal powder is more than 10 탆, the sintering ability of the tungsten-copper alloy may be deteriorated during the copper infiltration step (S200), and defects such as cracks and delamination It is difficult to expect an increase in the thermal conductivity and the mechanical strength of the present invention.

Further, in the method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, in order to further improve the thermal conductivity and mechanical strength of the tungsten-copper clad alloy, the tungsten metal powder satisfies the following relational formulas 1 to 3 have:

[Relation 1]

1.5 占 퐉? D1? 3.5 占 퐉

[Relation 2]

4.0 占 퐉? D2? 6.0 占 퐉

[Relation 3]

0.5? H1 / h2? 1.5

(In the above relational expressions 1 to 3, D1 is the center size of the first peak having the smallest center size, with respect to the center size of the peak in the size distribution of the tungsten metal powder, D2 is the center size of the peak, H1 is the center height of the first peak, and h2 is the center height of the second peak.

In one embodiment of the present invention, the size distribution of the tungsten metal powder may be measured using Dynamic Light Scattering (DLS). In detail, the size distribution of the tungsten metal powder may be measured under conditions of a temperature of 25 and a sample concentration of 0.01 to 0.1 wt%. The size distribution of the tungsten metal powder may be a size distribution shown by the diameter of the particles and the number of particles having the diameter. On the other hand, a size distribution of at least bimodal may mean that at least two peaks exist in the size distribution of the tungsten powder. At this time, the particles (particle diameter) corresponding to the center of the peak are the center sizes, the particles belonging to the first peak having the smallest center size are the first particles, and the particles belonging to the second peak having the largest center size 2 particles.

As described above, the tungsten metal powder according to the present invention has a bimodal distribution or satisfies the relational expressions 1 to 3, so that the copper is infiltrated into the above-mentioned tungsten formed body during the copper infiltration step S200 to form a uniform tungsten- And it is also possible to prevent the occurrence of defects such as cracks and voids on the inside or the surface of the tungsten-copper alloy.

In the method of manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the tungsten metal powder may be pressurized at 1 to 30 Ton / cm < 2 > during the step (S100) of manufacturing the tungsten compact.

Accordingly, the tungsten formed body according to one embodiment of the present invention can satisfy the following relationship:

[Equation 5]

0.70? D / d? 0? 0.95

[In the above-mentioned relational expression 5, d is the apparent density of the tungsten compact, and d0 is the theoretical density of the tungsten compact.]

When the relationship (5) is satisfied, the shape-retaining ability of the tungsten formed body according to the present invention can be improved. Copper is infiltrated into the tungsten formed body at a certain amount during the copper infiltration step (S200) And can be uniformly formed on the surface. These tungsten-copper alloys also enable diffusion bonding with copper metal.

Meanwhile, the above-described tungsten compact forming step (S100) may include a mixing step of a tungsten powder and a binder, a drying step, a sorting step, a molding step, and the like. However, such a process is generally sufficient for a method commonly used in this field, so a detailed description of the structure is omitted.

Next, the copper infiltration step S200 will be described. The copper-impregnating step (S200) may refer to a step of manufacturing a tungsten-copper alloy material by using the tungsten formed body and copper in the above-described tungsten compact forming step (S100).

In detail, the copper infiltration step (S200) includes the steps of: preparing copper on one side or both sides of the tungsten compact so that molten copper in the melted state is infiltrated into the tungsten compact; And a second step of heating the molten copper to infiltrate into the tungsten compact.

In one embodiment of the present invention, the copper in the first step may have a purity of 99% or more, and the present invention may use a plate-shaped member made of copper.

In another embodiment of the present invention, the second step may be a step of heating the tungsten formed body and the copper after the first step in a reducing atmosphere. In describing the present invention, the term "reducing atmosphere" may refer to an environment in which an oxide present in a metal compound is removed by reaction with a reducing gas or converted into another material. For example, the reducing gas may contain hydrogen or ammonia .

In addition, the second step may be performed at a temperature higher than the melting point of copper. In one embodiment of the present invention, the heating temperature in the second step may be 1100 to 1600 ° C. When the heating temperature is satisfied, the present invention can remove oxides remaining on the copper or tungsten surface, and copper can be uniformly formed in the tungsten-copper-containing gold material and on the surface thereof. Meanwhile, the heating temperature in the second step is preferably 1200 to 1500 ° C, and more preferably 1400 to 1500 ° C to achieve the object of the present invention, but the present invention is not limited thereto.

Meanwhile, as a specific and non-limiting example of the present invention, the holding time in the copper infiltration step (S200) may be 1 to 20 hours.

Meanwhile, in the method for manufacturing a tungsten-copper clad alloy according to an embodiment of the present invention, the tungsten-copper alloy material produced through the second step may contain 5 to 30% by weight of copper. If the copper content is less than 5% by weight, defects such as delamination may be generated at the interface at the time of diffusion bonding with a copper metal material to be described later, whereby the mechanical strength and ductility are weakened, and the thermal conductivity property is rapidly deteriorated . On the other hand, when the content of copper exceeds 30% by weight, it is likely to be deformed from an external impact, so that the shape-retaining ability is lowered, and it is difficult to expect an increase in thermal conductivity with an increase in copper content.

Meanwhile, the present invention may further include a step of cooling the tungsten-copper alloy in an inert atmosphere between the copper infiltration step (S200) described above and the diffusion bonding step between tungsten-copper and oxygen-free copper. The inert atmosphere may be an atomosphere containing nitrogen or argon.

Further, in another embodiment of the present invention, the copper infiltration step (S200) described above can perform the infiltration step using a continuous heat treatment apparatus using a belt. Accordingly, the purity of the tungsten-copper alloy according to the present invention can be improved and the efficiency of the process can be increased.

Next, the diffusion bonding step (S300) of tungsten-copper and copper will be described. The diffusion bonding step (S300) of tungsten-copper and copper is performed by providing an OFHC oxygen-free high-conductivity copper plate on one side or both sides of the tungsten-copper alloy produced in the copper infiltration step S200 Hot-pressing, and the solid-phase diffusion bonding of the tungsten-copper alloy and the oxygen-free copper may be performed.

Specifically, the oxygen-free high-conductivity copper (OFHC) may have a purity of 99.9% or more at the diffusion bonding step S300 of the tungsten-copper and oxygen-free copper. As a preferred example, the purity of oxygen-free copper may be 99.99% or more. When the purity of the oxygen-free copper is 99.9% or more or 99.99% or more, the tungsten-copper clad alloy according to the present invention can exhibit a higher thermal conductivity, and the tungsten-copper alloy layer and the oxygen- It is possible to prevent generation of defects such as cracks and delamination.

On the other hand, the hot pressing may be performed at a temperature lower than the melting point (m.p .: about 1084 ° C) of the copper. In one embodiment of the present invention, the hot pressing may be performed at 850 to 1050 캜, preferably at 920 to 1020 캜. When the temperature of the hot pressing is less than 850 占 폚, tungsten atoms and copper atoms do not sufficiently diffuse, and bonding due to solid-phase diffusion becomes difficult. Further, when the temperature of the hot pressing exceeds 1050 DEG C, a liquid phase is formed between the tungsten-copper alloy and the oxygen-free copper to generate a large amount of tungsten-copper compound. Therefore, The oxygen-free copper bonding is inhibited, and the bonding reliability is lowered.

Accordingly, when the hot-pressing is performed at a temperature lower than the melting point of copper or is performed in the temperature range, the tungsten-copper clad alloy according to the present invention has a structure in which the tungsten-copper alloy and the oxygen- - Crack-like gaps are unlikely to occur at the junction of the copper alloy layer and the oxygen-free copper layer, the thermal conductivity of the junction can be improved, and the thermal resistance can be reduced.

Further, since copper or a copper alloy having excellent thermal conductivity and excellent electrical conductivity is formed on at least one surface of the tungsten-copper alloy, it is easy to discharge heat from the semiconductor element to the outside, and a tungsten-copper clad alloy The plating ability can be improved.

As a specific and non-limiting example of the present invention, the holding time in the diffusion bonding step S300 of the tungsten-copper and oxygen-free copper may be 1 to 20 hours.

Further, as another specific and non-limiting example of the present invention, diffusion bonding may be performed by hot pressing in a vacuum atmosphere in a standby state during the diffusion bonding step (S300) of the tungsten-copper and oxygen-free copper.

At this time, the hot pressing may be performed by pressurizing the oxygen free copper plate located on one side or both sides of the tungsten-copper alloy at 1 to 100 Ton / cm < 2 >. When the load applied to the tungsten-copper alloy and the oxygen-free copper is less than 1 Ton / cm 2, it becomes difficult to sufficiently bond the tungsten-copper alloy and the oxygen-free copper, A gap may be generated. On the other hand, if it exceeds 100 Ton / cm 2, the load to be loaded is excessively high, so that cracks may be generated inside the tungsten-copper clad alloy of the present invention.

In summary, the method for producing a tungsten-copper clad alloy according to the present invention includes the step (S100) of producing a tungsten compact, the copper infiltration step (S200), and the diffusion bonding step (S300) of copper- The heat conduction characteristics are excellent, and the mechanical deformation that occurs during the manufacturing process can be prevented.

The present invention also includes a clad alloy formed by the above-described method for producing a tungsten-copper clad alloy.

The clad alloy according to the present invention comprises a first layer made of the above-mentioned tungsten-copper alloy; And a second layer of oxygen-free copper formed on one or both sides of the first layer.

In order to produce a heat sink using the tungsten-copper clad alloy of the present invention, it is necessary to mold the clad alloy into a desired shape. It can be seen that tungsten used as the material of the first layer is hard and difficult to process. For this reason, it is difficult to apply the press-punching method known as a method of easily performing molding, for example. Accordingly, in the clad alloy in which these layers are laminated, the processing can be facilitated as the thickness of the second layer is smaller than that of the first layer.

Accordingly, the clad alloy according to one embodiment of the present invention can satisfy the following relational expression 4:

[Relation 4]

1.1? T1 / T2? 2.1

(In the above relational expression 4, T1 is the thickness of the first layer made of the tungsten-copper alloy, and T2 is the thickness of the second layer made of the oxygen-free copper.)

The clad alloy according to the present invention preferably has a T1 / T2 of 1.3 to 1.9, more preferably 1.45 to 1.75, in view of further improved thermal conductivity and mechanical strength.

Meanwhile, the clad alloy according to one embodiment of the present invention satisfying the relational expression 3 may have a thermal conductivity of 150 to 250 W / m · K in the vertical direction.

The present invention also includes a heat sink including the above-described clad alloy.

Hereinafter, the present invention will be described in detail with reference to the following examples. However, the present invention is not limited to the following examples.

Example 1

tungsten Shaped body  Produce

500 g of a first tungsten powder having an average particle diameter of 2.3 탆, 500 g of a second tungsten powder having an average particle diameter of 4.7 탆, and 4 g of a modified polyetylene glycol (HS-BD-25 available from Kobunshi Kogyo Co., Ltd.) This was put into a rotary evaporator, and the solvent was removed by mixing and heating. Then, the solvent-removed mixed powder was dried in a dryer maintained at 120 ° C. The dried powder was screened by 200 mesh, and then a tungsten compact was produced by using a press molding machine. At this time, the molding pressure was 17.5 Ton / cm 2.

Manufacture of tungsten-copper alloy ( Cu10% W )

Next, a copper sheet was placed on the tungsten formed body and charged into a heat treatment furnace in a hydrogen atmosphere to prepare a tungsten-copper alloy having about 10% by weight of copper impregnated therein. At this time, the infiltration temperature was 1430 DEG C and the process holding time was 7 hours. The infused tungsten-copper alloy was then cooled in a nitrogen atmosphere.

Tungsten-copper Clad  Alloy manufacturing (copper / tungsten-copper / copper)

The cooled tungsten-copper alloy was placed in an upper portion and a lower portion of an oxygen free copper (OFHC) sheet, followed by diffusion bonding in vacuum using a hot press to produce a final tungsten-copper clad alloy. The diffusion bonding temperature was 970 ℃, the process holding time was 6 hours, and the hot pressing pressure was maintained at 19 Ton / ㎠.

Example 2

The procedure of Example 1 was repeated except that the molding pressure was changed to 12.2 Ton / cm < 2 > A tungsten-copper alloy having about 15% by weight of copper infiltrated according to Example 2 was prepared.

Example 3

The same procedure as in Example 1 was carried out except that the molding pressure was set to 8.7 Ton / cm < 2 > A tungsten-copper alloy having about 20% by weight of copper infiltrated according to Example 3 was prepared.

Example 4

The procedure of Example 2 was repeated except that 500 g of a second tungsten powder having an average particle diameter of 4.7 탆 was used so as to have a monododal distribution in the production of the tungsten compact.

Comparative Example 1

A single tungsten-copper alloy was produced in the same manner as in Example 2 except that the preparation was performed only up to the tungsten-copper alloy production (Cu15% W).

Comparative Example 2

A single tungsten-copper alloy was produced in the same manner as in Example 3 except that the preparation of tungsten-copper alloy (Cu 20% W) was performed.

Comparative Example 3

A tungsten compact was produced in the same manner as in Example 2 except that tungsten powder having a monodomal distribution and an average particle diameter of 15 탆 was used.

Measurement example 1

SEM photographs and components of the tungsten-copper clad alloy prepared in Examples 1 to 3 are shown in FIGS. 3 to 5. FIG. FIG. 3 is a cross-sectional SEM photograph of the tungsten-copper alloy according to Example 1 and an analysis result of the EDS component. FIG. 4 is a cross-sectional SEM photograph of the tungsten- FIG. 5 is a cross-sectional SEM photograph of the tungsten-copper alloy according to the third embodiment and the analysis result of the EDS component.

Referring to the SEM photographs of FIGS. 3 to 5, it can be seen that copper is uniformly infiltrated into the tungsten formed body to produce a tungsten-copper alloy, and voids such as voids are not present.

On the other hand, referring to the analysis results of the EDS component in FIGS. 3 to 5, it was slightly higher than the sedimentation amount for copper as shown in Examples 1 to 3 described above. That is, the mass ratio of the tungsten and copper is about 80:15 to 65:29.

6 is a SEM photograph of a section of the tungsten-copper clad alloy produced in Example 2. FIG. 6 (a) shows a first layer 100 made of a tungsten-copper alloy and a second layer 200 made of anoxic copper formed on the first layer 100. FIG. 6 (b) shows a tungsten- A first layer 100 made of a copper alloy and a second layer 201 made of oxygen-free copper formed under the first layer 100.

Referring to FIGS. 6A and 6B, a diffusion of about 1 to 50 μm is formed between the first layer 100 made of the tungsten-copper alloy and the second layer 200 or 201 made of oxygen-free copper. It can be seen that the bonding layer is formed, and the diffusion bonding layer is formed by solid phase diffusion bonding of tungsten atoms and copper atoms. Also, it was confirmed that defects such as cracks and delamination generated in the conventional CMC alloy 3 shown in FIG. 1 were not generated.

Measurement example 2

The thermal conductivity and thermal expansion coefficient of the tungsten-copper clad alloy prepared in Examples 1 to 3 are shown in Tables 1 and 2, respectively.

[Table 1]

[Table 2]

As shown in Table 1 and Table 2, the thermal conductivity of the tungsten-copper clad alloy according to the present invention shows a thermal conductivity of 180 to 200 W / mK in the thickness direction (vertical direction) The thermal expansion coefficient of the tungsten-copper clad alloy is 8 to 10 ppm / K.

Measurement example 3

Sections of the tungsten-copper clad alloy prepared in Examples 1 to 4 and Comparative Example 3 were confirmed by SEM. In Table 3, the product quantities of the tungsten-copper clad alloy and defective PASS quantities without defects were recorded. As a result, it was confirmed that the tungsten-copper clad alloy according to Comparative Example 3 is smaller than the crack size generated in the conventional CMC alloy, but still has minute cracks.

 [Table 3]

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

100: first layer, 200, 201: second layer

Claims (12)

a) preparing a tungsten compact by pressing a tungsten metal powder having a bimodal distribution and having an average particle diameter of 10 占 퐉 or less (excluding 0);
b) impregnating the tungsten mold with copper to produce a tungsten-copper alloy containing 10 to 20% by weight of copper; And
c) providing oxygen-free copper on at least one surface of the tungsten-copper alloy and subjecting the tungsten-copper alloy and the oxygen-free copper to diffusion bonding by hot pressing,
Wherein the tungsten metal powder satisfies the following relational expressions (1) to (3), the tungsten-copper alloy having a tungsten-copper alloy which prevents diffusion of the tungsten-copper alloy into the tungsten- Method of producing clad alloy:
[Relation 1]
1.5 占 퐉? D1? 3.5 占 퐉
[Relation 2]
4.0 占 퐉? D2? 6.0 占 퐉
[Relation 3]
0.5? H1 / h2? 1.5
(In the above relational expressions 1 to 3, D1 is the center size of the first peak having the smallest center size, with respect to the center size of the peak in the size distribution of the tungsten metal powder, D2 is the center size of the peak, H1 is the center height of the first peak, and h2 is the center height of the second peak.
The method according to claim 1,
Wherein the tungsten metal powder is pressurized at 1 to 30 Ton / cm < 2 > during the step a).
The method according to claim 1,
Wherein the copper is infiltrated in a reducing atmosphere at 1100 to 1600 占 폚 in the step b).
The method according to claim 1,
In the step c), the hot pressing is performed at a temperature lower than the melting point of copper.
5. The method of claim 4,
Wherein the hot pressing is performed at 850 to 1050 占 폚.
The method according to claim 1,
In the step c), the hot pressing is performed at a pressure of 1 to 100 Ton / cm < 2 >.
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