JPS62202534A - Capillary for wire bonding - Google Patents

Abstract

PURPOSE:To inhibit the adhesion of a conductor and electrode powder, to improve hardness, abrasion resistance and heat-dissipating characteristics and to lengthen life by forming at least a nose section in a capillary by specific polycrystalline ceramics. CONSTITUTION:At least a nose section in a capillary 1 for wire bonding is shaped by alumina polycrystalline ceramics having purity of 99.9% or more and a mean pore diameter of 1mum or less. Consequently, the defective connection of a wire is difficult to be generated because a conductor and electrode powder to the nose section hardly adhere on the nose section, and the breaking and abrasion of the nose are reduced and life is lengthened because strength and abrasion resistance are increased and heat-dissipating characteristics are improved. The wires can be bonded stably, thus stabilizing the quality of a semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capillary used for wire bonding of semiconductor devices such as LSIs and ICs.

[Conventional technology]

In semiconductor devices, thin i-wires made of gold or aluminum with a diameter of about 0.015 to 0.1 mm are used to connect the electrodes of the semiconductor chip and the lead electrodes of the puff cage, and this connection process (wire bonding) for,
As shown in FIG. 3, a capillary 1 was used, which was equipped with a pore 1a having a diameter of about 0.025 to 0.1 mm, through which the conducting wire was delivered to the tip.

This capillary 1 has been widely used which is made entirely of alumina polycrystalline ceramics having a purity of about 98χ or alumina single crystal such as ruby or sapphire.

[Problems with conventional technology]

However, in the case of conventional capillaries made of alumina polycrystalline ceramics, due to voids and pinholes of 1 μm or more that exist on the surface, conductive wire and electrode powder easily adheres to the tip, and when a large amount of this deposit accumulates, the pores form. This was causing clogged holes in 1a, broken conductors, and loop abnormalities. moreover,
The tip of this capillary is always at about 300°C, and when the conductor is crimped onto the electrode at a high speed of about 14 times per second, it is hit by the electrode and can instantaneously reach a high temperature of about 1000°C. As a result, the tips were severely chipped and worn due to heat shock, making them unusable in a relatively short period of time.

In addition, in the case of capillaries made of alumina single crystals such as ruby and sapphire, there is less adhesion of conductive wires and electrode powder to the tip and less wear, but due to micro-cranks that occur during the manufacturing process of the capillary itself, Chips and bends often occur during handling, such as when attaching capillaries to a bonding device, and for every capillary that can complete its lifespan through bonding, approximately 50x of capillaries become unusable during the process. Furthermore, ruby and sapphire have a problem in that they are expensive compared to alumina polycrystalline ceramics.

[Means for solving problems]

In view of the above, in the present invention, at least the tip of a capillary for wire bonding is formed of polycrystalline alumina ceramic having a purity of 99.9% or more and an average pore diameter of 1 μm or less.

〔Example〕

The capillary 1 according to the present invention, as shown in FIG.
It is equipped with a pore 1a through which the conductive wire is sent out to the tip. This capillary 1 is entirely made of alumina polycrystalline ceramic with a purity of 99.9% or more, and has an average pore diameter of 1 μm or less.

Examples of such a capillary 1 include one with an alumina purity of 99.90χ and one with an alumina purity of 99.93χ.
I made a prototype of χ. Table 1 shows a comparison of the characteristics with a conventional capillary having an alumina purity of 98X and an average pore diameter of 1 μm or more.

Table 1 As is clear from Table 1, magnetic 1.
The l1h2 capillary is a conventional example 11111.
It can be seen that compared to the L3 capillary, the Vickers hardness and bending strength are greater, and the thermal conductivity is also higher.

Furthermore, the 1lhl capillary, which has the highest alumina purity, has a bulk specific gravity of 3.98, which is closer to an alumina single crystal (bulk specific gravity 3.99), and is also closer in properties to an alumina single crystal.

Next, a wire bonding test was conducted using these capillaries and capillaries made of other materials. Ten capillaries of each type were prepared and bonded with gold wire under the same conditions, and the relationship between the number of bondings and the connection state of the conductor wires was investigated, and the average values for each were as shown in Table 2.

Table 2 O: No abnormalities Δ: Some wire connection failures occurred x: Wire connection failures occurred frequently, making this second table unusable.
As can be seen from the table, the capillary made of N[Ll ultra-hard material can be used for about 300,000 cycles, and the capillary made of alumina polycrystalline ceramic (purity 98χ) in Case 2 is used for about 600,000 cycles.
After about 10,000 bonding cycles, many wire connection failures occurred and the device became unusable. Capillaries made of N12 alumina polycrystalline ceramics (purity 98χ) often get clogged with deposits, and although they can be reused by cleaning the deposits midway through, they can only be used about 1 million times before becoming completely unusable due to wear. It became. Also, 1lh
Capillaries made of ruby No. 3 can be bonded about 4 million times, but three capillaries were unusable due to chipping or bending when attached to the bonding device. In contrast, the alumina polycrystalline ceramics (purity 99.9
The capillary made of χ) and the capillary made of alumina polycrystalline ceramics No. 5 (purity 99.93χ) can be bonded up to 2.4 million times and 4 million times, respectively, and they do not break when attached to the bonding device. There were no cracks or creases.

As described above, the capillary according to the present invention has less adhesion of conducting wires and electrode powder, has high hardness and wear resistance, and has good heat dissipation characteristics, so it is less likely to chip or wear due to heat shock and has a long life. Furthermore, since it does not have a single crystal structure like ruby, even if it has microcranks, it will not grow beyond a certain point, and there is less risk of breakage or chipping during handling.

The capillary in the above example is made of 99.9% or more alumina with a sintering aid such as MgO added,
By performing any one of the hot pressing method, old P (hot isostatic pressing) treatment, vacuum firing, etc., a very dense structure can be obtained, and the average pore diameter can be set to 1 μm or less. In addition, we prototyped capillaries made of alumina polycrystalline ceramics with various alumina purity and average pore size, and conducted the same bonding test as above. The tip is severely chipped and worn, and the average pore diameter is 1μ.
If the diameter was larger than m, the adhesion of conductive wires and electrode powder was large, and both had short lifespans.

In addition, in the above embodiment, the entire capillary was made of alumina polycrystalline ceramic with a purity of 99.9% or more and an average pore diameter of 1 μm or less, but the capillary is not limited to this, as shown in FIG. Alternatively, only the tip portion S may be formed of an alumina polycrystalline ceramic having a purity of 99.9% or more and an average pore diameter of 1 μm or less, and the other portions may be made of a different material.

〔Effect of the invention〕

As described above, according to the present invention, at least the tip of the capillary for wire bonding is made of alumina polycrystalline ceramics having a purity of 99.9% or more and an average pore diameter of 1 μm or less. Because there is less adhesion of conductor or electrode powder to the wire, poor wire connections are less likely to occur.Also, the wire has high strength and wear resistance, and has good heat dissipation properties, so there is less chipping and wear on the tip, which not only extends the lifespan but also provides stability. Accordingly, it is possible to perform wire bonding with a high quality, and the quality of the semiconductor device can be stabilized.

Furthermore, it is possible to provide a capillary for wire bonding that has many features such as lower cost than ruby and sapphire.

[Brief explanation of drawings]

FIG. 1 is a partially broken sectional view showing a wire bonding capillary according to the present invention, FIG. 2 is a partially broken sectional view showing another embodiment of the wire bonding capillary according to the present invention, and FIG. 3 is a conventional FIG. 2 is an enlarged cross-sectional view showing the tip of the capillary for wire bonding. 1: Capillary 1a: Pore F: Deposit

Claims (1)

[Claims] 1. A capillary for wire bonding, characterized in that at least a tip portion thereof is formed of alumina polycrystalline ceramic having a purity of 99.9% or more and an average pore diameter of 1 μm or less.