JPH10340934A - Bonding tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure excellent flatness and abrasion resistance of tool working face and a sufficient bonding strength between the tip of a tool and a shank by brazing the tip of a tool, obtained by depositing polycrystalline diamond on a sintered substrate, to the shank made of an austenite based low thermal expansion cast iron thereby facilitating the machining. SOLUTION: The tip 14 of a tool, obtained by depositing polycrystalline diamond on a sintered substrate, is brazed to a shank made of an austenite based low thermal expansion cast iron to obtain a tool for enhancing machinability of the shank, flatness of the working face of the tool, and the positional accuracy with respect to an apparatus fixing part 11. Strain at the joint due to difference of thermal expansion is relaxed at the time of brazing the shank and the tip 14 of the tool and flatness is sustained at the tip 14 of the tool even if heating and cooling are repeated. Furthermore, a high bonding strength is attained because the austenite based low thermal expansion cast iron exhibits a good wettability to many brazing filter metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a bonding tool. More specifically, the present invention provides a TAB (Tape Automated) that is excellent in flatness of the tool working surface, has little wear of the tool working surface material, and has little deformation of the tool working surface.
The present invention relates to a bonding tool for an applied bonding process.

[0002]

2. Description of the Related Art In a TAB process, electrodes of an LSI chip and leads of a film carrier are connected. FIG.
FIG. 4 is an explanatory view of a TAB step. On the thermal insulator 2 on the heating stage 1, the film carrier 6 having the inner lead 5 is moved via the tape guide 7 to the chip 4 positioned by the chip guide 3, and the position of the inner lead and the electrode 8 are brought to coincide. In this state, the heated bonding tool 9 is pressed down by the pressing cylinder 10 to press the inner lead against the electrode, and to form an Au-Sn eutectic alloy between the inner lead and the electrode, or Is bonded to the inner lead by thermocompression bonding. In order to perform good bonding between the electrode and the lead, it is important to maintain the uniformity of the height of the electrode, the flatness of the working surface of the bonding tool, the wear resistance, and the uniform temperature distribution. Polycrystalline diamond having excellent wear resistance and high thermal conductivity has been developed as a material for the working surface of a bonding tool. Since polycrystalline diamond has a small coefficient of linear expansion, a low thermal expansion material is selected for the substrate on which the polycrystalline diamond film is formed. Furthermore, in the shank of the bonding tool, at the joint between the tool tip and the shank, which consist of polycrystalline diamond with a low coefficient of thermal expansion and a sintered substrate, the difference in the coefficient of thermal expansion between the two parts causes a decrease in bonding strength and the occurrence of peeling. In order to prevent this, the use of materials having a low coefficient of thermal expansion has been attempted. For example, Japanese Patent No. 2520971 discloses that
The coefficient of linear expansion from room temperature to 600 ° C. is 7.5 × 10 ⁻⁶ / ° C.
The following metal or alloy shanks have been proposed.
Examples of such a metal or alloy having a low coefficient of thermal expansion include Kovar, Invar alloy, molybdenum, tungsten, W-Cu alloy, and cemented carbide. However, such metals and alloys have poor wettability to a brazing material used for joining a shank to polycrystalline diamond or a SiC substrate or the like, which serves as a bonding tool working surface. Cracks easily occur on the surface. Further, such metals and alloys have poor workability, and there is a problem that shank processing of a bonding tool which requires processing into a complicated shape is difficult and cannot be produced economically advantageously.
Further, such metals and alloys are also expensive in materials themselves, and cause high cost in addition to the problem of workability.
Therefore, there is a demand for a bonding tool that has good wettability with a SiC substrate or the like, can easily be processed into a complicated shape, and can be manufactured economically and advantageously.

[0003]

SUMMARY OF THE INVENTION The present invention can be easily manufactured, and has excellent flatness of a tool working surface.
T with less wear of the tool working surface material, less deformation of the tool working surface, and a strong connection between the tool tip and the shank
The purpose of the present invention is to provide a bonding tool for the AB process.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the tip of a tool in which a polycrystalline diamond film has been deposited on a sintered body substrate has an austenitic low thermal expansion. By brazing to a cast iron shank, the shank can be easily processed,
In addition, it has been found that a bonding tool having excellent flatness and wear resistance of the working surface of the tool and having a large joining strength between the tool tip and the shank can be obtained. Based on this finding, the present invention has been completed. That is, the present invention provides (1)
A bonding tool in which a tool tip obtained by depositing a polycrystalline diamond film on a sintered substrate is brazed to a shank, wherein the material of the shank is austenitic low thermal expansion cast iron,
(2) The austenitic low thermal expansion cast iron has a linear expansion coefficient of 8 to 12 × 10 ⁻⁶ K ⁻¹ at room temperature to 600 ° C.
(1) The bonding tool according to (1), and (3) the austenitic low thermal expansion cast iron contains 0.8 to 3.0% by weight of carbon,
1.0 to 3.0% by weight of silicon, 30.0 to 34.0% of nickel
Weight percent and 4.0 to 6.0 weight percent cobalt.
A bonding tool according to the above mode (1) or (2).

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The bonding tool of the present invention
A tool tip obtained by depositing a polycrystalline diamond film on a sintered substrate is brazed to a shank made of austenitic low thermal expansion cast iron. 2A and 2B are explanatory views of the bonding tool. FIG. 2A is a front view, FIG. 2B is a side view, and FIG. 2C is a bottom view. In the shank of the bonding tool, the mounting portion 11 for the pressurized cylinder, the heater mounting hole 12, the thermocouple mounting hole 13
The tool tip 14 is brazed to the tip. In the present invention, the material of the sintered body substrate at the tip of the tool is not particularly limited.
C, Si ₃ N ₄ , AlN and the like can be mentioned. Among them, SiC can be particularly preferably used because it has both heat resistance, strength at high temperatures, low thermal expansion, and high thermal conductivity. In the present invention, the method of depositing the polycrystalline diamond film on the sintered substrate is not particularly limited, for example, a hot filament method, a microwave plasma method, a high-frequency plasma method, a DC discharge plasma method, an arc discharge plasma jet method, A combustion flame method and the like can be mentioned.

In the present invention, a shank made of austenitic low thermal expansion cast iron is used. Austenitic low-thermal-expansion cast iron has better workability than low-thermal-expansion alloys that have been used in the past. Therefore, the working accuracy of the shank is improved, and the flatness of the tool working surface and the device mounting portion (Fig. 2- Position accuracy with respect to 11) can be improved. Also, by using a shank made of austenitic low thermal expansion cast iron, when brazing the shank and the tool tip, the distortion of the joint generated due to the difference in the coefficient of thermal expansion is reduced, and even if heating and cooling are repeated, The flatness of the tool tip is maintained. In addition, austenitic low thermal expansion cast iron has good wettability to many brazing materials, so that a large bonding strength can be obtained. further,
In the austenitic low thermal expansion cast iron, the strain between the shank and the tool tip during brazing is reduced by the action of graphite dispersed in the matrix. In the present invention, there is no particular limitation on the brazing material for brazing the shank and the tool tip, for example, gold brazing, silver brazing, palladium brazing, copper brazing, brass brazing, phosphor copper brazing, nickel brazing,
Aluminum alloy brazing and the like can be mentioned. Among them, an active silver braze in which Ti, Ta, or the like is added to a silver-based brazing material can be particularly preferably used.

In the present invention, the austenitic low thermal expansion cast iron used as a material for the shank preferably has a linear expansion coefficient of from 8 to 12 × 10 ^-6 K ^-1 at room temperature to 600 ° C. Since the linear expansion coefficient of polycrystalline diamond is very small, a material with low thermal expansion has been conventionally selected for the sintered substrate on which the polycrystalline diamond film is deposited, and the shank that joins the tip of the tool has been expanded as much as possible. The idea of using a material with a small rate to prevent the destruction of the joint and to realize the flatness of the tool working surface was dominant. However, although the polycrystalline diamond at the tip of the tool is a substance having a low thermal expansion, the substrate used therein has a larger coefficient of thermal expansion than the polycrystalline diamond. Also, such as a pressurized cylinder that drives the bonding tool
Since the other part of the bonder is made of a normal steel material for machine tools, using a low thermal expansion material for the shank of the bonding tool does not necessarily improve the accuracy of the entire bonder. In the bonding tool of the present invention, the low thermal expansion polycrystalline joined to the tool tip by gradually reducing the linear expansion coefficient with the shank material and polycrystalline diamond from the linear expansion coefficient of the material forming the bonder body. The difference in deformation caused by the difference in the coefficient of linear expansion between the diamond and the bonder body is reduced, the accuracy of the bonder as a whole is improved, and the flatness of the tool working surface can be maintained. In the present invention, if the linear expansion coefficient of the austenitic low-thermal expansion cast iron is less than 8 × 10 ⁻⁶ K ⁻¹ at room temperature to 600 ° C., the accuracy when the shank and the bonder body are joined may be reduced. If the coefficient of linear expansion of the austenitic low thermal expansion cast iron exceeds 12 × 10 ⁻⁶ K ⁻¹ , cracks may easily occur at the joint between the shank and the tool tip due to repeated heating and cooling.

In the present invention, the austenitic low thermal expansion cast iron has a carbon content of 0.8 to 3.0% by weight and a silicon content of 1.0 to 3.0%.
It is preferable to contain 0% by weight, 30.0% to 34.0% by weight of nickel and 4.0% to 6.0% by weight of cobalt. By containing 0.8 to 3.0% by weight of carbon and 1.0 to 3.0% by weight of silicon, carbon precipitates in cast iron as an appropriate amount of flake graphite or spheroidal graphite, and has good castability and workability. Sex is maintained. If the carbon content is less than 0.8% by weight, the carbon becomes carbide and does not precipitate as graphite, so that castability may be impaired. 3.0% by weight carbon
If it exceeds 300, the amount of graphite deposited will be excessive and castability may be impaired. When the content of nickel is 30.0
If the amount is less than 3% by weight or exceeds 34.0% by weight, the coefficient of linear expansion may be too high. If the cobalt content is less than 4.0% by weight or exceeds 6.0% by weight, the coefficient of linear expansion may be too high. In the bonding tool of the present invention, a tool tip having a polycrystalline diamond film having excellent wear resistance is brazed to a shank made of austenitic low thermal expansion cast iron having good workability and an appropriate linear expansion coefficient. Therefore, it is possible to obtain a high-precision bonder excellent in flatness of the tool working surface.

[0009]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 An SiC intermediate layer having a thickness of 40 μm was formed on a SiC substrate having a thickness of 4 mm and a size of 10 mm × 10 mm by a microwave plasma method. Next, the SiC substrate is heated to 900 ° C.
0.8% by volume of methane under reduced pressure of Torr. 99.2% by volume of hydrogen
Gas mixture is introduced for 20 hours by the hot filament method, a polycrystalline diamond film having a thickness of 80 μm is formed on the SiC intermediate layer, and a mirror-finished surface is lapped to obtain a tool tip. Was. Room temperature to 6
Using an austenitic low-thermal-expansion cast iron [Enomoto Casting Co., Ltd., CN-5] having a linear expansion coefficient of 8.7 × 10 ⁻⁶ K ⁻¹ at 00 ° C., a shank having a shape shown in FIG. Produced.
Processing of the shank was easy. The tool tip was brazed to this shank using an active silver braze to obtain a bonding tool. The flatness of the tool working surface is 50
When heated to 0 ° C., the concave was 0.8 μm. The bonding tool was attached to a bonder, the temperature of the tool working surface was maintained at 500 ° C., and a shot test was continued for 28 days at a heating stage with a tool load of 5 kg and a pressure cycle of 30 times / min. After the test, the flatness of the tool working surface was 1.3 μm concave when heated to 500 ° C., and the change in flatness before and after the test was 0.5 μm.
When the interface between the tool tip and the shank after the test was completed was observed using a scanning electron microscope, no change was observed. Example 2 The material of the shank has a linear expansion coefficient from room temperature to 600 ° C. of 11.
Example 1 except that austenitic low thermal expansion cast iron of 1 × 10 ⁻⁶ K ⁻¹ [Enomoto Casting Co., Ltd., CS-5] was used.
The same operation was repeated. The flatness of the tool working surface before the shot test was 1.2 μm in a state where the tool was heated to 500 ° C.
m convex, flatness of tool working surface after shot test is 5
When heated to 00 ° C., the concave was 0.5 μm, and the change in flatness before and after the test was 1.7 μm. When the interface between the tool tip and the shank after the test was completed was observed using a scanning electron microscope, no change was observed. Comparative Example 1 The material of the shank was changed so that the linear expansion coefficient from room temperature to 600 ° C. was 7.0.
The same operation as in Example 1 was repeated except that a 54 wt% Fe-28Ni-Co alloy of × 10 ^-6 K ^-1 was used. The flatness of the tool working surface before the shot test was 2.0 μm concave when heated to 500 ° C., and the flatness of the tool working surface after the shot test was 1.0 μm heated to 500 ° C. It was concave and the change in flatness before and after the test was 1.0 μm. When the interface between the tool tip and the shank after the test was completed was observed using a scanning electron microscope, no change was observed. Comparative Example 2 The material of the shank was changed from room temperature to 600 ° C. with a linear expansion coefficient of 7.6.
The same operation as in Example 1 was repeated, except that a cemented carbide of JIS K10 class of ^10-6 K ^-1 was used. The flatness of the tool working surface before the shot test was 1.5 μm concave when heated to 500 ° C., and the flatness of the tool working surface after the shot test was heated to 500 ° C.
The convexity was 1.5 μm, and the change in flatness before and after the test was 3.0.
μm. When the interface between the tool tip and the shank after the test was completed was observed using a scanning electron microscope, cracks were observed. In addition, the surface of the shank was discolored to green due to the loss of Co and became brittle. Comparative Example 3 The material of the shank was changed from room temperature to 600 ° C. with a linear expansion coefficient of 5.1.
Example 1 except that molybdenum which was × 10 ⁻⁶ K ⁻¹ was used.
The same operation was repeated. The flatness of the working surface of the tool before the shot test was 0.5 μm when heated to 500 ° C.
m concave, the flatness of the tool working surface after the shot test is 2.7 μm convex when heated to 500 ° C.,
The change in flatness before and after the test was 3.2 μm. When the interface between the tool tip and the shank after the test was completed was observed using a scanning electron microscope, cracks were observed. Further, the shank surface turned yellow and became brittle. Examples 1-2 and Comparative Examples 1
Table 3 shows the results of No. 3.

[0010]

[Table 1]

From the results shown in Table 1, it can be seen that the bonding tools of Examples 1 and 2, in which the material of the shank is austenitic low thermal expansion cast iron, showed a change in the flatness of the tool working surface even after a 28-day shot test. And there is no abnormality at the interface between the tool tip and the joint of the shank. The shank used in Examples 1 and 2 was easy to process. On the other hand, the material of the shank is Fe-N
In Comparative Example 1, which is an i-Co alloy, the amount of change in the flatness of the working surface of the tool and the point that no abnormality occurs at the interface between the tool tip and the junction of the shank are the same as in the example, but Processing of this shank was significantly more difficult than the processing of the shank of the example. In Comparative Example 2 in which the cemented carbide was used as the material for the shank, the change in the flatness of the tool working surface was large, and cracks occurred at the interface between the tool tip and the joint of the shank. In addition, the coefficient of linear expansion is F
In Comparative Example 3 in which molybdenum smaller than the e-Ni-Co alloy was used as the material for the shank, the amount of change in the flatness of the tool working surface was larger than in Comparative Example 1, and the tool tip was joined to the shank. From the occurrence of cracks at the boundary surfaces of the portions, it can be seen that the smaller the coefficient of linear expansion of the material of the shank, the better the result.

[0012]

The bonding tool of the present invention has good workability of the shank, can be easily manufactured, has excellent flatness of the working surface of the tool, has little wear on the working surface of the tool, and has a small working surface of the tool. The deformation is small, the connection between the tool tip and the shank is strong, and it can be suitably used in the TAB process.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a TAB step.

FIG. 2 is an explanatory diagram of a bonding tool.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating stage 2 Thermal insulator 3 Chip guide 4 Chip 5 Inner lead 6 Film carrier 7 Tape guide 8 Electrode 9 Bonding tool 10 Pressure cylinder 11 Mounting part to pressure cylinder 12 Heater mounting hole 13 Thermocouple mounting hole 14 Tool tip Department

Claims (3)

[Claims] 1. A bonding tool obtained by brazing a tool tip having a polycrystalline diamond film deposited on a sintered body substrate to a shank, wherein the material of the shank is austenitic low thermal expansion cast iron. tool. 2. The bonding tool according to claim ¹ , wherein the linear expansion coefficient of the austenitic low thermal expansion cast iron is 8 to 12 × 10 ⁻⁶ K ⁻¹ at room temperature to 600 ° C. 3. An austenitic low thermal expansion cast iron comprising 0.8 to 3.0% by weight of carbon, 1.0 to 3.0% by weight of silicon, 30.0 to 34.0% by weight of nickel and 4.0 to 3.0% by weight of cobalt. 6.0
The bonding tool according to claim 1, wherein the bonding tool contains a weight%.