JPH02288350A - Bonding tool - Google Patents

Abstract

PURPOSE:To enable simple and accurate positioning of a pair of junction electrodes, to improve quality and efficiency of bonding junction, and to exchange a bonding tool readily by forming a specified gap to a surface containing an end side which is a bonding junction section of a tool body to provide a pair of electrode layers. CONSTITUTION:A pair of electrodes 20 for bonding junction consist of a pair of electrode layers 20 which are separatedly formed with a gap 30 of a fixed interval on a tool body 10 which is composed of an insulating material by applying usual thin film formation technique, etc. In this case, an interval between the bonding junction electrodes 20 for bonding junction can be set accurately, thereby producing no step to right and left electrodes. Furthermore, since right and left electrodes are formed integrally to the tool body 10 which is a piece of part, no mechanism or connecting member to connect junction electrodes is required. When a tool is exchanged, exchanging of an entire tool body whereto an electrode layer is formed eliminates the necessity of positioning of all junction electrode.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bonding tool, and in detail,
The present invention relates to a bonding tool that heats and presses a bonding wire to a surface to be bonded when mounting or mounting an electronic component such as a C-chip using wire bonding.

[Conventional technology]

Bonding tools with various structures have been developed, and among them there is a bonding tool with a structure called a parallel gap method.

4 and 5 show the structure of a parallel gap type bonding tool, in which a pair of wedge-shaped electrodes 1.
A pair of wedge-shaped electrodes 1.1 are electrically connected by the bonding wire W while applying pressure to the surface to be bonded such as the circuit C of the wiring board l) with the bonding wire W at the tip of the bonding wire W.
A current is passed between them, and the bonding wire W is heated by the resistance heat generation of the bonding wire W itself, thereby bonding the bonded surface C.
It is designed to be bonded to metal. A bonding tool having such a structure is widely used because it can efficiently heat only the bonding wire W, so it has the advantage that it does not adversely affect peripheral circuits and the like.

[Problem to be solved by the invention]

In the parallel gap type bonding tool described above, the pair of wedge-shaped electrodes 1゜l mechanically joins two separately manufactured parts made of suitable conductive materials with an insulating material in between. , can be assembled integrally,
There was a problem in that manufacturing, such as assembly and processing, of this wedge-shaped electrode was difficult. The reason is as follows.

The pair of wedge-shaped electrodes 1, 1 generate heat by passing a current through the bonding wire W of a certain length between the points where their respective tips contact each other, so the heating temperature has a large effect on the bonding performance of the bonding wire W. To set accurately, a pair of wedge-shaped electrodes 1. It is necessary to accurately set the gap of l. Typically, a wedge-shaped electrode 1. The interval l is set to about 10 μi, but if it becomes narrower than this, the amount of heat generated by the bonding wire W will become small. On the other hand, if the interval becomes wider, the wedge-shaped electrode 1.
The entire bonding wire W between 1 does not generate heat uniformly,
Excessive heat generation may occur locally, causing the bonding wire W to melt, or sufficient pressing force may not be transmitted to the bonding wire W in the gap between the wedge-shaped electrodes 1.1.

Furthermore, if there is a step in the vertical direction at the tips of the left and right wedge-shaped electrodes 1.1, it will not be possible to bring both wedge-shaped electrodes 1.1 into even contact with the bonding wire W, resulting in uneven pressurization. Therefore, the height difference between the tips of the left and right wedge-shaped electrodes 1 must be set to at least 31 m or less. It is extremely difficult to set the spacing and the vertical position of 1 with high precision as described above, which reduces the productivity of the bonding tool and causes cost increases.

When using a bonding tool, the bonding tool is usually replaced every 100,000 bonding operations, which means that even under normal working conditions, the tool needs to be replaced frequently, about once a day. Each time the tool is replaced, the position of the wedge-shaped electrode 1.1 must be set as described above, which results in extremely poor work efficiency, and also causes errors in the position of the wedge-shaped electrode 1.1 each time the tool is replaced. There is a possibility that this may occur, and the quality performance of the bonding joint is likely to vary.

Therefore, it is an object of this invention to accurately and easily set the position of a pair of bonding bridges in a parallel gap type bonding tool as described above, to improve the quality performance of bonding, and to reduce the work of replacing the bonding tool. Another objective is to provide an easy bonding tool.

[Means to solve the problem]

A bonding tool according to the present invention that solves the above problems is provided by forming a predetermined gap on the surface of the tool body, which is entirely made of an insulating material, including the tip surface that becomes the bonding joint, and connecting a pair of electrodes. I try to have layers.

The entire tool body is made of an insulating material such as diamond, and like a normal bonding tool, the structure for attaching the tool to the holder and the electrode layer provided with wire holes for inserting the bonding wire, etc. It is made of a material that is electrically conductive and can withstand heat and pressure during bonding. For example, a conductive diamond is pasted on the tool body, or a thin layer of molybdenum, tungsten carbide, etc. is deposited on the surface of the tool body. , can be formed using ordinary thin film forming techniques. As the material for the electrode layer, a conductive ceramic thin film, a conductive SiN4 film, etc. can also be used. As the thin film forming technique, an appropriate method is adopted from among CVD, vacuum evaporation, PVD, etc., depending on the type of conductive material constituting the electrode layer.

The electrode layer needs to be formed at least on the tip surface of the tool body that will become the bonding joint. In addition, in order to make it easier to connect the wiring that supplies current to the electrode layer or to make it easier to form the electrode layer, it is possible to form the electrode layer from the tip to the upper side of the side, or over the entire surface of the tool body. It is preferable to keep it.

The gap provided between the pair of electrode layers can reliably insulate and isolate both types of electrode layers. The spacing between the electrode layers covering the tip surface of the tool body is set to such an extent that bonding can be performed satisfactorily. That is, this distance causes the bonding wire led to the bonding joint to generate resistance heat by an amount corresponding to the distance. Therefore, this interval is
It needs to be defined to the extent that bonding can be performed satisfactorily. Since the portions of the tool body other than the tip surface are not directly related to bonding, the gap interval and shape may be different from those of the tip surface.

As a method for forming a gap between electrode layers, various patterning means in ordinary thin film technology or microfabrication technology employed in semiconductor manufacturing etc. can be applied. For example, after forming an electrode layer on the entire surface of the tool body, the electrode layer in the gap area is removed by laser processing, etc., or after covering the gap area of the tool body with an appropriate resist material, the electrode layer is formed on the entire surface of the tool body. Examples include a method in which a layer is formed and the electrode layer in the gap part is peeled off together with the resist material, and a method in which a process is performed so that the electrode layer is not formed only in the gap part of the tool body when forming a thin electrode layer. It will be done.

[For production]

A pair of electrodes that perform bonding, as in the past,
Separate wedge-shaped electrodes are not mechanically assembled and joined, but are formed separately with regular gaps on a single tool body made of an insulating material by applying normal thin film formation technology. Since the electrode layer is made up of a pair of electrode layers, the distance between the bonding electrodes can be set accurately, and there is no difference in level between the left and right electrodes. Since the left and right electrodes are integrally formed in the tool body, which is one component, there is no need for a mechanism or connecting member to connect the bonding electrodes. When replacing the tool, if the entire tool body on which the electrode layer is formed is replaced, it is not necessary to set the position of the bonding electrode each time.

〔Example〕

Next, the present invention will be explained in detail below with reference to the drawings showing examples.

1 and 2 show the structure of a bonding tool, in which an electrode layer 20 made of a conductive material such as conductive diamond is provided on the surface of a tool body 10 made of an insulating material such as diamond. The electrode layer 20 is provided on the entire surface of the wool body 10, including the tip surface 12, and is separated from the left and right by an annular gap 30 that goes around the tool body 10 from the center of the tip surface 12 to the side and top surfaces. A pair of electrode layers 20 and 20 are formed. The tip end surface 12 of the tool body 10 that contacts the bonding wire W is placed between the left and right electrode layers 20.2 with the gap 30 in between.
0 is covered, and the electrode layer 20.20 on this tip surface 12 becomes a bonding joint.

In addition, in the figure, in order to make the explanation easier to understand, there is a clear step on the tip surface 12 of the tool body 10 between the left and right electrode layers 2020 and the surface of the tool body 10 exposed in the gap 30 between them. However, in reality, the thickness of the electrode layer 20 is extremely thin, and the surfaces of the electrode layer 20 and the tool body 10 are almost the same surface.

A wire hole 11 passing through the tool body 1O in an oblique direction is provided in a side portion of the tool body 10, and a bonding wire W is inserted and held in this wire hole 11 to perform a bonding operation.

Although omitted in the figure, a pair of electrode layers 20.2
0 is connected to wiring for supplying current, and is also provided with a mechanism for holding and moving the bonding tool. These structures are implemented with 1, similar to conventional bonding tools.

The bonding tool described above can be used in exactly the same way as a normal bonding tool, and as shown in FIG. Press with the tip surface 12 of. The left and right electrode layers 20 are attached to the bonding wire W.
When a current is passed between the electrode layers 20 and 20 with the electrodes 20 and 20 in contact with each other, the current flows through the bonding wire W between the electrode layers 20 and 20, generating heat. The bonding wire W is bonded to the circuit C by this heat generation and pressure applied by the bonding tool. The bonding tool according to this invention includes:
In addition to the usage shown in the figure, it can be used in various wire bonding operations for semiconductor chips, wiring circuits, etc. in the same way as a normal bonding tool.

Next, Figure 3 shows one of the bonding tool manufacturing methods.
An example is shown. First, as shown in step (a), the tool body 10 is manufactured using diamond or the like as a material by ordinary machining or molding, and then, as shown in step (b), the entire surface of the tool body 10 is An electrode ff120 is formed on. After that, in the step (as shown in C1), if the electrode layer 20 at the gear part 30 is removed by means such as laser processing,
A bonding tool as shown in FIG. 1 can be manufactured.

〔Effect of the invention〕

The above-described bonding tool according to the present invention separates the electrode layer provided on the surface of the tool body made of an insulating material by a gap at a constant interval, thereby forming a pair of bonding electrodes. There is no need to mechanically join and assemble wedge-shaped electrodes, which are manufactured as separate left and right parts, as in the past, and the spacing between a pair of bonding electrodes can be set extremely accurately. There is no difference in height between the electrodes. Therefore, the effort of adjusting the position of the bonding electrodes can be saved, and the quality performance of the bonding bonding is also good and stable.

The formation of the electrode layer on the tool body and the formation of the gap are
It can be performed accurately and easily using normal thin film formation technology and microfabrication technology that are common in semiconductor manufacturing, etc., so bonding tools with uniform shape accuracy and quality performance of bonding electrodes can be manufactured efficiently in large quantities. becomes possible.

To replace the bonding tool, you only need to replace the entire tool body on which the electrode layer is integrally formed.
There is no need to disassemble, assemble, and position the wedge-shaped electrode every time the tool is replaced, and the tool can be replaced extremely quickly and easily.

[Brief explanation of drawings]

Fig. 1 is a side view of a bonding work state showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view taken along line nn from the previous time, Fig. 3 is a schematic process diagram showing an example of the manufacturing method, and Fig. 4 is A perspective view of the conventional example, and FIG. 5 is an enlarged side view in a state of use. ■0...Tool body 20.20...Electrode layer...
Gap W...Bonding wire Figure 1 Agent's name Patent attorney Shigetaka Awano Haka 1 person Figure 2

Claims (1)

[Claims] 1. A bonding tool in which a pair of electrode layers are provided with a predetermined gap formed on the surface of the tool body, which is entirely made of an insulating material, including the tip surface that becomes the bonding joint.