JPH049240A - Method for cutting fine metallic wire - Google Patents

Abstract

PURPOSE:To efficiently obtain wire pieces of a prescribed length with high accuracy by moving holding parts grabbing the end of a fine metallic wire and pulling out the wire by a specified length, then cutting the wire by means of cutting blades provided in proximity to the holding parts. CONSTITUTION:The holding parts 3a, 3b are moved to grab and fix the fine metallic wire 1 from the right and left. Clampers 5a, 5b are then opened and the holding parts 3a, 3b are moved downward by (d) while the metallic wire 1 is held gripped. The metallic wire 1 is eventually drawn out by the length (d) from guides 2 in this way. The clampers 5a, 5b are closed again and the blades 4a, 4b are operated to cut the metallic wire 1. The blades 4a, 4b are immediately returned to home positions. The cut wire piece 10 falls when the holding parts 3a, 3b grabbing the metallic wire 1 are released. Finally, the state exactly equal to the initial state is restored when the holding parts 3a, 3b and the blades 4a, 4b are risen by (d).

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention uses gold r This invention relates to a method for cutting a wire into a certain length.

[Conventional technology]

Various methods are used to connect the electrodes of the IC chip and external leads.

There is a method of connecting using ultra-thin wiring wire (bonding wire), but another method that has become widely used is to sandwich a metal protrusion called a hump between the chip electrode and the lead and bond by thermocompression.

T A B (Tape Automated Bon
ding) method is a technique that is attracting attention as a representative of the latter. In this method, bumps are formed in advance either on the electrodes of the IC chip or on the lead tips on the TAB tape, and then the IC chip electrodes and the TAB tape having the leads are bonded to form the bumps. The two are joined together by overlapping each other through the material. In addition to the TAB method, humps are also used in the flip chip method.

Up until now, the method of making humps provided for such uses has mainly been based on the metsuki method.

In other words, the mainstream methods are to directly plate metal to form bumps on the electrodes of IC chips, or to transfer bumps formed by plating on a glass substrate etc. to the lead tips on the TAB tape side. ing.

However, the method using plating has disadvantages in that it requires large equipment and is also subject to restrictions on the composition of the metal used as the bump. In addition, if bumps were to be formed by directly plating the electrode portions of IC chips, the chip itself would have to go through the plating process, which would deteriorate the yield of the chips, which was a problem.

As a way to overcome these drawbacks, bump forming methods that do not involve plating have come to be considered. We proposed a method to obtain spherical bumps using surface tension by cutting wires to a specified length and melting and solidifying them at intervals (Japanese Patent Application No. 1-3202).
No. 96). The spherical bump thus produced is used by being thermocompression bonded to the tip of the lead, etc. (Japanese Patent Application No. 1-234917).

Until now, the most common metal used for such humps was high-purity gold. Gold is certainly an effective metal for humps, but it is thought that there were constraints in the process of forming the humps using plating, which made it difficult for other metals to be considered as objects.

On the other hand, a new method of melting any piece of metal wire to form a bump without regard to metal wire makes it possible to use any metal with characteristics suitable for a joining member as a hump. has expanded significantly. Furthermore, even if gold is used as in the past, when forming bumps by plating, it is necessary to use high-purity gold close to pure gold. It is possible to fabricate bumps with any composition possible. In addition to gold, copper, silver, and various alloys based on these can now be easily formed into bumps.

When producing bumps by melting pieces of metal wire, it is necessary to cut the metal wire to a strictly constant length in order to obtain bumps of uniform size. In order to increase the precision of cutting the length, use material with the thinnest wire diameter possible.
It goes without saying that it is more convenient to make the cutting length longer, but since the size of the bump is generally smaller than 100 microns in diameter, even if the metal wire used is made thinner, the cutting length will be 0. It has to be as short as .5m or less, or about 2m at most.

Moreover, since soft metals are mainly used for bumps in fishing boats, metal wires made from these materials are extremely difficult to handle as they bend under their own weight. In particular, in order to increase the precision of the cutting length, it is necessary to accurately feed the easily bendable metal wire to a certain length, but it is necessary to feed the easily bendable metal wire to a certain length with a diameter of about 10 microns for thin wires ranging from several tens of microns made of soft metal. It is extremely difficult to send out a single thin wire accurately without bending it.

Therefore, when attempting to accurately cut such thin metal wires for bump materials with an existing cutting machine that has a feeding mechanism at a constant pitch, it is necessary to bundle multiple thin metal wires or arrange them in parallel on a tape and fix them. Therefore, it is effective to cut the material after it has been treated so as not to hinder feeding. The method disclosed in the previous Japanese Patent Application No. 1-320296 was based on this idea.

[The section that the invention seeks to solve]

The object of the present invention is to use a
It is possible to cut large quantities of soft material metal wires such as gold, which are drawn to a diameter of about microns or less, efficiently and with high cutting accuracy by means that do not allow adhesives or alignment materials to be mixed in as impurities. It is an object of the present invention to provide a method that can cut wire pieces into lengths such that the wire pieces have a length of , and can cut the wire pieces without intertwining with each other after cutting.

[Means to solve the problem]

The present invention has the following features: (1) After pulling out a certain length of the fine metal wire from the guide outlet side by moving the holding part that grips the end of the fine metal wire, a cutting blade provided close to the holding part is provided. (2) A method for cutting a fine metal wire, characterized in that the fine metal wire is cut by a feed roll disposed on the exit side of the guide. A method for cutting a fine metal wire, characterized in that the fine metal wire is cut with a cutting blade provided with a cutting blade.

The present invention relates to cutting metal wire, and the cut metal wire pieces are then arranged and melted so as not to interfere with each other, so as to form a spherical hump. It is. Therefore, rather than thinking about cutting alone,
It is important to cut the material so that it can be easily used in the next melting process.

During the melting process, care must be taken first and foremost to avoid contamination with impurities. In general, the characteristics necessary for a hump may be significantly affected by even a small amount of impurity. Therefore, if impurities are mixed in the cut metal wire piece during the cutting process, it is necessary to remove the impurity by some method before melting. Furthermore, during the melting process, it is also necessary that each piece of metal wire be melted separately without interfering with each other. This is because if the melting process begins with a plurality of metal wire pieces in contact with each other, a large bump is obtained by combining the plurality of metal wire pieces, which is useless.

From the above, the cutting of ultra-fine metal according to the present invention is firstly a method that does not introduce impurities, and secondly, the cut metal wire pieces do not get entangled, and if possible, the cut metal wire pieces are not tangled. The aim was to create a method that would make it easy to control even the spacing between each piece of metal wire that falls into the container. In order to satisfy these aims, it is necessary to cut the bare fine metal wire as a single wire one by one, so that the cut wire pieces can be processed one by one.

When cutting a metal wire of a normal diameter to a certain length, the metal wire is fed out intermittently at a certain length using a feed roll, etc., rotated by a step motor, and the cutting blade is operated at each step. By cutting, a large number of gold rIA wire pieces of uniform length can be easily obtained. However, in the case of fine metal wires, when trying to feed them with feed rolls, they tend to bend, making it difficult to accurately feed them. In order to solve this problem, it has become clear that it is effective to pull out the fine metal wire passed through the guide from the exit side of the guide. As a method to accurately draw out fine metal wires of a certain length,
The following two methods were particularly effective.

The first method is to provide a holding part for gripping and fixing all or part of the tip of the fine metal wire that will be cut next, and to cut the fine metal wire through this holding part. In this method, the fine metal wire is pulled out by moving it away from the guide by a length exactly corresponding to the length of the wire.

As another method, a feed roll is installed on the exit side of the guide, and the fine metal wire is rotated by a step, a motor, etc. adjusted so that one step corresponds to the length to be cut. The method of eliciting this was equally effective. According to this method, there is no need to worry about bending, which tends to occur when fine metal wires are fed from the rear, and the problem of the fine metal wires getting stuck in the narrow part of the guide is extremely unlikely to occur. It was confirmed that

Having achieved a mechanism in which fine metal wires of a fixed length are drawn out in this way, we next investigated a cutting method that would be compatible with this fine metal wire supply mechanism. For accurate cutting, it is necessary to operate the cutting tool with the closest part of the tool fixed as possible.

The farther the fixed part is from the blade, the more the fine metal wire will be moved by the movement of the blade itself during cutting, and cutting accuracy will inevitably deteriorate accordingly. Moreover, it is necessary to limit the part to be fixed to the part as close as possible to the tip of the fine metal wire.

If possible, I would like to grasp the tip of the fine metal wire that is about to be cut off, which is outside the blade, rather than between the guide and the cutter, so that the fine metal wire that has been deformed by the grip will be After being cut off, the next position that the gripping part tries to fix is a position that has been largely unaffected by the deformation caused by the previous gripping or cutting, so the reliability of the method of the present invention is extremely high when automating it. This is because.

The present invention was achieved by combining the above findings, and the details will be explained in more detail later based on Examples.

[Effect]

The fine metal wire to be cut is intermittently pulled out from the exit side of the guide by a length corresponding to a predetermined cutting length. The fine gold rIAvA is pulled out by the operation of the feed roll or holding section on the exit side of the guide. The cutting is
This is done by a cutting blade provided close to the feed roll or holding part. Since the fine metal wire is pulled out from the exit side rather than being fed into a narrow guide hole, cutting work suitable for mass production can be performed without the fine metal wire bending at the large guide entrance or becoming clogged inside.

〔Example〕

Example 1 FIG. 1 is a schematic diagram showing the basic operation of the present invention.

The diameter is 2DI for fine metal H1! m gold wire was used.

The fine metal vA1 is drawn out downward through a guide 2 made of quartz and having a narrow hole with an inner diameter of 30 μm. The tip of the fine metal wire 1 is connected to the holding parts 3a and 3b during release.
, and the same (reaching between the cutting blades 4a and 4b that are being released).

Furthermore, clampers 5a and 5b were provided on the entry side of the guide 2 to prevent the fine metal wire I from naturally flowing out through the guide 2 (FIG. 1(A)).

The holding parts 3a and 3b are made of ceramics, and were first operated to grip and fix the fine metal Ml from the left and right sides (FIG. 1(b)). Next, clampers 5a, 5
b is released and the holding parts 3a and 3b are attached to the fine metal wire 1.
While still holding it, move it downward by d. Cutting knife 4
Razor blades are used as a and 4b, but since their vertical movement is linked to the holding parts 3a and 3b, the cutting blades 4a and 4b are also moved to d by the downward movement of the holding parts. By the operations up to this point, the fine metal wire has been pulled out from the guide 2 by a length d (FIG. 1(c)).

Here, the clampers 5a and 5b are closed again, and the cutting blades 4a and 4b are operated in the horizontal direction to remove the fine metal wire 1.
was cut (Figure 1 (d)). Immediately after cutting, the cutting blades 4a and 4b are pulled back to their original standby positions, and the fine metal wire 1 is further removed.
When the holding parts 3a and 3b that were holding the wire were also released, the cut wire piece lO fell (FIG. 1 (e)). Finally, the holding part 3a.

3b and the cutting blades 4a and 4b together by an amount d (Fig. 1(a)), this state has been restored to exactly the same state as the initial state shown in Fig. 1(a). Recognize. Therefore, by repeating the steps (a) to (f) in FIG. 1, the fine metal wire 1 can be successively cut into wire pieces of uniform length d.

The wire diameter d of the fine metal wire was tested with 0.3, 0.50.
It was possible to cut with an accuracy of within m.

Example 2 In the previous example 1, the roles of the clampers 5a and 5b are as follows:
The purpose was to prevent the fine metal wire from coming out and returning naturally from the guide when holding parts 3a and 3b, which act to grip and pull out the fine metal wire on the exit side of the guide, are in a released state. This role can also be fulfilled by another means other than the ramper, as in the first embodiment.

In this embodiment, as shown in FIG.
By making it spiral, we decided to make it have the function of a clamper. Holding part 3 a.

3b and the same cutting tools 4a and 4b as in Example 1 were used. When the fine metal wire 1 passes through the inside of the spiral guide 21, it comes to rest at the pulled-out position due to the resistance given by the inner wall of the guide. Cuts were made with the same precision.

Example 3 FIG. 3 is a schematic diagram of the apparatus used. 2 is a fine metal wire, 2 is a guide, 3a and 3b are holding parts, and 4a and 4b are cutting blades. A feed roll 6a is provided on the exit side of the guide 2.
, 6b was installed. This feed roll was made of ceramics and had a diameter of 3fi, and was installed at a position 10 m away from the exit side of the guide 2.

The roll was rotated by a step motor (not shown), and the fine metal wire was intermittently drawn out to the exit side of the guide 2 in constant lengths.

In the case of this embodiment, the fine metal wire is automatically fed to the position of the cutting blade by the action of the feed roll as described above, so that both the holding parts 3a and 3b and the cutting blades 4a and 4b are vertically spaced. When both the holding parts 3a and 3b and the cutting blades 4a and 4b are released, the feed roll rotates 1 step to hold the tip of the fine metal wire 1 pulled out. After the parts 3a and 3b moved horizontally to grip and fix, the cutting blades 4a and 4b also moved horizontally to cut the fine metal vA1.

A gold wire with a diameter of 30 μm was used as the fine metal wire 1, and the cutting length was set to 0.4=n, allowing for accurate cutting.

Example 4 The method of the present invention cuts fine metal wires in the form of single wires with high precision, but in order to further improve the cutting efficiency,
It is also possible to combine multiple cutting elements for each single line and perform parallel processing. Figure 4 shows an example.
This is a case where a book of fine metal wires l is cut at the same time. The guide 2 is made of ceramics, and is split in two and has grooves for passing fine metal wires inside, and is used with the left and right sides aligned. The feed roll 6a6b is also made of ceramics, and in order to pass the fine metal wire straight through,
It is a grooved roll. A step motor (not shown) is used to rotate the rolls, and the four fine metal wires 1 can be drawn out to the same length at the same time.

The holding parts 3a, 3b and the cutting blades 4a, 4b can also act on the four fine metal vAl at the same time, and when both are released, the feed roll rotates and pulls out a certain length of fine metal wire. , first, after the holding parts 3a and 3b are closed and the tip of the fine metal wire is fixed, the cutting blade 4a,
4b works and disconnects.

Using this method, it was possible to efficiently cut gold wire with a diameter of 20 μm into uniform wire pieces with a length of 0.8 mm.

〔Effect of the invention〕

Fine metal wires can be cut with high precision without coming into contact with impurities, and the cut wire pieces can be taken out individually, making it easy to feed them to the subsequent melting process. be.

[Brief explanation of drawings]

In the present invention, Fig. 1 is a schematic diagram for explaining the operation status of the cutting process, Fig. 2 is a schematic diagram when a part of it is replaced by another means, and Fig. 3 is a schematic diagram for explaining the operating status of the cutting process. FIG. 4 is a schematic diagram showing an example of a case in which the method of the present invention is carried out more efficiently. 1. Fine metal wire, 20.・Guide, 3a, 3b...
- Holding part, 4a, 4b... Cutting knife, 5a, 5b... Clamper 6a, 6b... Feed roll, 10,... Cut fine metal wire piece, 21... Spiral guide.

Claims (2)

[Claims] (1) By moving the holding part that grips the end of the fine metal wire, the fine metal wire is pulled out by a certain length from the guide outlet side, and then the fine metal wire is cut with a cutting blade provided close to the holding part. A method for cutting a fine metal wire, characterized by cutting the fine metal wire. (2) A fine metal wire characterized in that the fine metal wire is pulled out by a certain length from the guide by a feed roll placed on the guide outlet side, and then the fine metal wire is cut by a cutting blade provided close to the feed roll. How to cut the line.