JPH04306856A - Manufacture of bonding tool for gold-gold bonding - Google Patents

Abstract

PURPOSE:To prevent residual silicon from reacting with a gold wire by a method wherein a sintered diamond which contains silicon carbide ceramic coupling agent and a small amount of silicon is covered with vapor-synthetic diamond, which is fixed to a shank so that the covered surface of the sintered diamond is made to serve as a bonding working surface. CONSTITUTION:A sintered diamond 2 which contains silicon carbide ceramic coupling agent and a small amount of silicon is covered with a vapor phase- synthetic diamond 1, which is fixed to a shank so as to enable the covered surface of the sintered diamond to serve as a bonding working surface. The diamond coat 1 is formed as thick as 20-1500mum, and it is preferable that the thickness of the diamond coat 1 ranges from 20 to 200mum. If the thickness concerned is less than 20mum, it is difficult to perform a precision attaining finish onto the bonding working surface of the diamond 1 by polishing, and if the thickness is over 1500mum, cracks are induced in the bonding working surface due to the inner distortion of the diamond film concerned.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bonding tool for gold-gold bonding. More specifically, in manufacturing a bonding tool having a structure in which a diamond sintered body is attached to a shank, the present invention forms a vapor-phase synthesized diamond film on the surface of the diamond sintered body with extremely good adhesion, provides excellent performance, and provides gold-gold bonding. The present invention relates to a method of manufacturing a bonding tool that has a long life even when used for bonding.

0002

[Prior Art] Commonly known as TAB (Tape Auto)
A bonding tool for rated bonding is a tool for bonding lead wires to an IC chip or an IC substrate. Usually, the bonding tool is heated to a temperature range of 300 to 600°C and subjected to repeated loads. Because bonding materials are used over a long period of time, they must be made of materials that have excellent heat resistance, abrasion resistance, and thermal conductivity, and are resistant to the adhesion of molten metal solder to the surface. Bonding tools are made by fixing materials such as single crystal diamond, diamond sintered bodies, CBN sintered bodies, etc. to a metal shank using methods such as sintering or brazing, or directly attached to the tool using heat-resistant alloys such as Mo or Inconel. The processed one is used. In recent years, the IC chips used in LCD TVs, calculators, watches, and IC cards have tended to become larger, and instead of single crystal diamond, which has size issues as a material, bonding using diamond sintered bodies allows for free selection of sizes. Its use for tools is increasing. Generally, diamond sintered bodies suitable for this purpose include those that use metals such as cobalt, molybdenum, and tungsten as binding materials, and those that use ceramics such as silicon carbide. Among these, those using a metal bonding agent have a heat resistance of 700℃ and can be used at a relatively low temperature of around 350℃, while those using a ceramic bonding agent have a heat resistance of 1100℃ and a temperature of 500℃. Can be used up to relatively high temperatures before and after. The TAB has inner lead bonding (which connects the IC chip and the lead wires formed on the film tape).
Internal lead bonding, I. L. There is B) and outer lead bonding (O.L.B.), in which lead wires of an IC chip are bonded to an IC substrate. I. L. Since O.B is carried out at a temperature range of 450 to 550°C, diamond sintered bodies using ceramics as a binder are often used. L. Since B is carried out in a temperature range of 250 to 350°C, a diamond sintered body using metal as a binder is often used. I. L. In B, lead wires are attached using a heated bonding tool to a large number of bumps made of materials such as gold, copper, and solder prepared as electrodes on the IC chip, and to a copper pattern formed on a film tape and lead wires plated with gold or tin. In contrast to the method of alloying and bonding all at once by pressing from the sides, recently the reverse method is to prepare bumps made of materials such as gold, copper, or solder on lead wires formed on film tape, and heat them to the aluminum electrodes on the IC chip. There is a method in which alloy bonding is performed at once by pressing a bonding tool that has been prepared from the lead wire side. Traditionally, alloy bonding of gold on the bump side and tin on the lead wire side has been commonly used as a bonding pattern for ICs and lead wires, but in recent years, gold bumps and tin lead wires have been used in terms of strength and contact resistance of the bonded portion. There is a trend toward a gold bump-gold lead wire bonding pattern, which is superior to the gold bump-gold lead wire bonding pattern. To bond gold bumps and tin lead wires, heat the bonding tool to a temperature range of 450 to 500°C and press the bonding tool against the tin lead wire for a relatively short time of about 0.2 seconds to melt the tin and bond it to the gold. Joining is performed by alloying reaction. On the other hand, bonding tools for bonding gold bumps and gold lead wires, which have become frequently used in recent years, require
The bonding tool is heated to a temperature range of 600° C. and pressed against the gold on the lead wire side for a relatively long time of 1 to 2 seconds, thereby diffusion bonding the gold bump and the gold lead wire. Conventionally, a diamond sintered body using silicon carbide ceramic binder has been used as a bonding tool material for bonding gold bumps and gold lead wires, but this diamond sintered body is usually used due to manufacturing process problems. Contains about 1 weight percent residual silicon. This means that when bonding gold bumps and gold lead wires, the residual silicon in the bonding tool material and the gold in the lead wires undergo an alloying reaction at a relatively low temperature of 370°C, making it impossible to maintain the cleanliness of the bonding surface. The number of times the bonding tool must be cleaned with a ceramic grindstone increases, resulting in a problem of lower work efficiency and shorter bonding tool life. Specifically, in the case of gold bump-tin lead wire bonding, the life of the diamond sintered bonding tool was 100,000 to 200,000 bonding times, but in the case of gold bump-gold lead wire, the lifespan of the diamond sintered bonding tool was 100,000 to 200,000 times. , depending on the bonding temperature, the bonding operation can only be performed about 40,000 to 80,000 times.

0003

[Problems to be Solved by the Invention] Under these circumstances, the present invention aims to eliminate residual silicon and gold leads in the diamond sintered body when using a bonding tool using a diamond sintered body with a silicon carbide ceramic binder. This was done for the purpose of providing a method for manufacturing a bonding tool that can prevent reactions with wires.

0004

[Means for Solving the Problem] As a result of extensive research in order to achieve the above object, the present inventors have developed a vapor phase synthesized diamond film on the bonding tool surface of a diamond sintered body made of a silicon carbide ceramic binder. It was discovered that the object could be achieved by forming a coating, and based on this knowledge, the present invention was completed. That is, the present invention is characterized in that a sintered diamond containing a silicon carbide ceramic binder and a small amount of silicon is coated with vapor-phase synthetic diamond, and the coated surface is attached to the shank as a bonding work surface. money to do
The present invention provides a method for manufacturing a bonding tool for gold bonding. In particular, the diamond film thickness is 20 μm to 150 μm.
The present invention provides a method for manufacturing a bonding tool for gold-gold bonding, characterized in that a bonding tool for gold-gold bonding is used that has a diameter of 0 μm, preferably in the range of 20 to 200 μm.

In the method of the present invention, a diamond film is coated on the surface of a diamond sintered body made of a silicon carbide ceramic binder by vapor phase synthesis, and the diamond film thickness is 20 μm to 1500 μm, preferably 20 μm.
It is necessary to use a material in the range of m to 200 μm. If this film thickness is less than 20 μm, it will be difficult to achieve precision finishing by polishing the bonding surface, and
If it exceeds m, cracks will occur during polishing of the bonding surface due to internal strain in the diamond film.

In the present invention, a diamond film is formed on the surface of a diamond sintered body made of a silicon carbide ceramic binder by vapor phase synthesis. There are no particular restrictions on the method of forming a diamond film by vapor phase synthesis, and methods conventionally used for forming diamond films by vapor phase synthesis, such as physical vapor deposition and chemical vapor deposition, can be used. Chemical vapor deposition methods such as microwave CVD, RF plasma CVD, DC plasma CVD, hot filament CVD, and ion beam CVD are preferably used.

In this way, a vapor-phase synthetic diamond film is formed on the surface of the diamond sintered substrate made of the silicon carbide ceramic binder. The thickness of this diamond film is usually 20 μm to 1500 μm, preferably 20 μm to 1500 μm.
The thickness is selected in the range of ~200 μm, and this film thickness ensures sufficiently strong adhesion of the diamond film to the diamond sintered body serving as the substrate. If the film thickness is less than 20 μm, the product yield will be poor due to difficulty in processing the surface of the bonding tool.
If it exceeds 500 μm, it is not preferable because internal strain in the diamond film may cause defects during processing, and the film formation time will be too long, resulting in a decrease in production efficiency.

In the manufacturing method of the present invention, the diamond sintered body made of a silicon carbide ceramic binder having a vapor phase synthesized diamond film on its surface is attached to a metal shank so that the diamond film surface becomes the bonding film surface. Be soldered. As the metal shank in the manufacturing method of the present invention, for example, one made of a low thermal expansion material such as tungsten, molybdenum, or an alloy thereof can be suitably used.

There are no particular restrictions on the brazing method, and any method conventionally used for brazing a diamond sintered body to a metal shank can be used. FIG. 1 is a cross-sectional view of one example of a bonding tool obtained by the method of the present invention, in which a diamond sintered body 2 with a vapor-phase synthetic diamond film 1 provided on the bonding surface is connected to a thermocouple mounting hole 3 and a heater. The structure is shown brazed to a metal shank 5 with mounting holes 4.

0010

[Function] In the present invention, by coating a diamond sintered body made of a silicon carbide ceramic binder containing a small amount of residual silicon with a vapor phase synthesized diamond film, the diamond sintered body This prevents the reaction between the silicon inside and the gold of the lead wire, and the diamond coating formed on it is made of pure diamond without any binders, so the bonding surface remains extremely clean during bonding, extending the life of the tool. It also improves greatly. The method of forming a vapor-phase synthetic diamond film in the method of the present invention can be used not only for bonding tools but also for wear-resistant tools such as work rests, shoes, center diamond contacts, and diamond dies.

[0011]

[Examples] The present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Note that the performance of the bonding tool obtained in the example was evaluated using the test apparatus shown in FIG. 2. That is, the bonding tool 6 is maintained at a predetermined bonding temperature by the heater 7, and the piston 9 is actuated by the air cylinder 8 to apply pressure of 25 kg/cm2 to the gold base 11.
The bonding surface was struck 500,000 times and the reaction between the bonding surface and the gold was observed after the strikes.

Example 1 Gas composition CH4/H2 volume ratio 1/99 gas pressure 40 Torr, filament temperature 2 on the surface of a sintered diamond containing a silicon carbide ceramic binder and a small amount of silicon.
A bonding tool was manufactured by forming a diamond film with a thickness of 100 μm by plasma CVD at a substrate temperature of 850° C. The condition of the bonding surface after this bonding tool was struck 500,000 times at a bonding temperature of 450° C. using the testing apparatus shown in FIG. 2 was observed. The bonding surface of the bonding tool of this example was kept extremely clean and did not react with gold at all, and there was no peeling or chipping from the substrate, indicating that the bonding tool was sufficiently durable for practical use.

Comparative Example 1 On the other hand, for comparison, a diamond sintered body bonding tool containing silicon carbide and a small amount of silicon as a binder before the vapor-phase synthetic diamond film forming process of Example 1 was used. When the impact was performed 100,000 times at the same temperature and under the same conditions as in Example 1, a reaction with gold was observed, and the bonding surface was so dirty that it could not be used in actual bonding work.

Example 2 A sintered diamond surface containing a silicon carbide ceramic bonding agent and a small amount of silicon has a gas composition of CH4/H2 volume ratio of 1/99, gas pressure of 40 Torr, and filament temperature of 2.
A bonding tool was manufactured by forming a diamond film with a thickness of 200 μm by plasma CVD at a substrate temperature of 850° C. The condition of the bonding surface after this bonding tool was struck 500,000 times at a bonding temperature of 550° C. using the testing apparatus shown in FIG. 2 was observed. The bonding surface of the bonding tool was kept extremely clean, had no reaction with gold, and had no peeling or chipping from the substrate, indicating that the bonding tool was sufficiently durable for practical use.

Comparative Example 2 On the other hand, for comparison, a diamond sintered body bonding tool containing silicon carbide and a small amount of silicon as a binder before the vapor-phase synthetic diamond film forming process of Example 2 was used. When the impact was performed 50,000 times at the same temperature and under the same conditions as in Example 2, a reaction with gold was observed, and the bonding surface was so dirty that it could not be used in actual bonding work.

Example 3 Gas composition CH4/H2 volume ratio 1/99 gas pressure 100 Torr, DC voltage 1500 on the surface of a sintered diamond containing a silicon carbide ceramic binder and a small amount of silicon.
Thickness: 500 μm by DC plasma CVD method under V conditions
A bonding tool was fabricated by forming a diamond film. The condition of the bonding surface after this bonding tool was struck 500,000 times at a bonding temperature of 600° C. using the testing apparatus shown in FIG. 2 was observed. The bonding surface of the bonding tool was kept extremely clean and did not react with gold at all, and there was no peeling or chipping from the substrate, indicating that the bonding tool was sufficiently durable for practical use.

Comparative Example 3 On the other hand, for comparison, in Example 3, the bonding tool of a diamond sintered body containing silicon carbide and a small amount of silicon as a binder before the film forming process of a vapor phase synthesized diamond film was used. When it was struck 30,000 times at the same temperature and under the same conditions as in Example 1, a reaction with gold was observed, and the bonding surface was so dirty that it could not be used in actual bonding work.

[0018]

According to the present invention, the silicon carbide ceramic binder and the diamond sintered body substrate containing a small amount of silicon are bonded to the silicon carbide ceramic binder and the silicon in the diamond sintered body during bonding and the lead is removed by the vapor phase synthesized diamond film firmly adhered to the diamond sintered body substrate. Since reaction of the wire with gold is prevented and the vapor phase synthesized diamond film does not contain any binder, the cleanliness of the bonding surface is maintained for an extremely long time, resulting in a bonding tool with a long life.

[0019]

[Brief explanation of drawings]

FIG. 1 is a sectional view of an example of a bonding tool obtained by the method of the present invention.

[0020]

FIG. 2 is a schematic diagram of a test device for evaluating the performance of the bonding tool obtained in the example.

[0021]

[Explanation of symbols]

1 Vapor phase synthetic diamond film 2　Diamond sintered body 3 Thermocouple mounting hole 4 Heater installation hole 5 Metal shank 6 Bonding tool 7 Heater 8 Air cylinder 9 Piston 10 Thermocouple 11 Gold pedestal 12 Ceramic pedestal

Claims (2)

[Claims] Claim 1: A sintered diamond containing a silicon carbide ceramic binder and a small amount of silicon is coated with vapor-phase synthetic diamond, and the coated surface is attached to a shank as a bonding work surface. A method for manufacturing a bonding tool for gold-gold bonding. Claim 2: The thickness of the diamond film to be coated is 20 μm.
The method for manufacturing a bonding tool for gold-gold bonding according to claim 1, characterized in that the thickness is in the range of ~1500 μm.