JPH0155578B2 - - Google Patents

Abstract

PURPOSE:To improve the efficiency of wire bonding operation, by forming both of bonding and soldering surfaces on the opposite end faces of a post. CONSTITUTION:The main body 5a of a square-pillar-shaped post is made of a first metal having a soldering property, such as nickel, and wire-connecting parts 5b, which are jointed to the oposite end faces of the main body 5a of the post respectively, are made of a second metal which can be bonded with wires by ultrasonic bonding. Each wire-connecting part 5b has a smaller surface area than the opposite and faces 5A of the main body 5a of the post. Moreover, each wire-connecting part 5b is formed, for instance, in the shape of a strip having a smaller width than that of the end face of the main body 5a of the post, and is jointed to the central portion of each end face of said main body. Accordingly, a surface B to which the ultrasonic bonding can be applied is formed in the center of each end face of the wire bonding post 5, while a surface A to which soldering can be applied is formed on both sides of the surface B, and thus the soldering and the ultrasonic bonding can be applied to each of the end faces.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a wire bonding post that is interposed between a bonding wire and a conductive portion of a substrate when forming a hybrid integrated circuit or the like.

Prior Art When configuring a hybrid integrated circuit by mounting chips of semiconductor elements (including integrated circuits) such as transistors and electronic components such as resistors and capacitors on a substrate, one side 1a of the chip 1 is mounted as shown in FIG. The chip 1 is attached to the board 2 by connecting the provided electrode to the conductive part 2a on the board 2 with solder 3.
A predetermined circuit is constructed by connecting the electrode 1c provided on the other surface 1b to another conductive portion 2b provided on the substrate 2 via the bonding wire 4 and the wire bonding post 5. There is.

Recently, as a wire bonding method, an ultrasonic bonding method is often used, and in this case, aluminum is used as the bonding wire from the viewpoint of cost and conductivity. In the ultrasonic bonding method, the metals to be joined are brought together and rubbed together by transmitting ultrasonic waves from the bonding head to the butt joint, which removes oxides on the metal surfaces and generates frictional heat. Both metals are joined together by melting the joint. In this case, the metals to be joined may be different types of metals, but in the case of different types of metals, the conditions are severe and productivity decreases, so generally the same types of metals are used. Therefore, when connecting the electrode 1c of the chip to the electrode 2b of the substrate by the wire bonding method using aluminum wire, the electrode 1c of the chip 1 is formed of aluminum and can be soldered as shown in FIG. Post main body 5a made of metal
The post body 5a of the post 5 is bonded using a wire bonding post 5 in which a wire connection portion 5b made of aluminum and a wire connection portion 5b are bonded together by a cladding method or the like.
is connected to the electrode 2b of the substrate 2 by solder 3, and both ends of the wire 4 are bonded to the electrode 1c of the chip 1 and the wire connection portion of the post 5. In this case, the thickness t of the wire connection portion 5b is about 10 μm, and the thickness of the post main body 5a is about 0.2 to 0.5 mm.

By the way, in the wire bonding post 5 used for this kind of purpose, the post main body 5a
Nickel is used as a metal that can be easily joined to aluminum and has solderability, but since nickel has almost the same color as aluminum, it is difficult to distinguish between the two, as shown in Figure 2. In the structure in which the wire connection portion 5b is bonded to one side of the post main body 5a, there is a drawback that many mistakes occur during assembly, such as misidentifying the bonding surface and the soldering surface, resulting in poor assembly work efficiency. Ta. In order to make it possible to distinguish between the bonding surface and the soldering surface, measures are taken such as making the shapes of both surfaces different, but generally wire bonding posts are approximately 1 mm square to 2 mm square. Since it is small, it is not easy to distinguish the shape of its surface, and it has not been possible to eliminate mistakes in identifying both sides.

OBJECTS OF THE INVENTION An object of the present invention is to provide a wire bonding post that eliminates the above-mentioned drawbacks by having a structure that eliminates the need to distinguish between a soldering surface and a bonding surface.

Structure of the Invention The present invention comprises a post main body made of a first metal that can be soldered, and a wire connection part made of a second metal to which a wire can be bonded and integrally joined to the post main body. This is an improved wire bonding post, and in the present invention, the wire connection portion is formed to have a surface area smaller than the surface area of both end surfaces of the post main body, and the wire connection portion is formed so as to have a surface area smaller than the surface area of both end surfaces of the post main body. are located in each.

In the above configuration, since the wire connection part has a smaller surface area than the post main body, both end surfaces of the post main body are formed with both a soldering surface that can be soldered and a bonding surface that can be bonded. Ru. Therefore, with the wire bonding post of the present invention, bonding and soldering can be performed on either side of the wire bonding post, and there is no need to identify the surface of the wire bonding post when assembling a hybrid integrated circuit or the like. .

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 3 shows one embodiment of the present invention, in which 5a is a prismatic post main body made of a first metal with solderability such as nickel, and 5b and 5b are respectively attached to both end surfaces of the post main body 5a. joined,
It is a wire connection part made of a second metal (of the same type as the metal constituting the bonding wire) that can be ultrasonically bonded with the wire, and each wire connection part 5b has a surface area larger than the surface area of both end surfaces 5A, 5A of the post main body 5a. also has a small surface area. In the illustrated example, each wire connection portion 5b is formed in a band-like shape having a width smaller than the width of the end surface of the post main body 5a, and each wire connection portion 5b is joined to the center of each end surface of the post main body 5a. ing. Therefore, a surface (bonding surface) B on which ultrasonic bonding is possible is formed at the center of each end surface of the wire bonding post 5, and surfaces (soldering surface) A on which soldering is possible are formed on both sides of the surface B. Soldering and ultrasonic bonding are also possible on the end faces.
Note that the metal forming the wire connection portion 5b and the metal forming the post main body 5a may be joined by pressure welding, or a thin film of the metal forming the wire connection portion 5b may be deposited on both end surfaces of the post main body 5a. It may be fixed by sputtering or the like.

The size of each wire connection portion 5b (the size of the bonding surface B) is such that a sufficient soldering surface A is secured on each end surface of the post 5, and the wire 4 can be applied to each end surface of the post 5 from any direction. The bonding surface is set to an appropriate size in consideration of the width of the wire and the size of the main body of the post so that the bonding surface can contact the wire with a sufficient area even if the wire is moved.

Figure 4 shows the above wire bonding post 5.
The wire 4 is bonded to the bonding surface B of the upper end surface of the post 5, and the soldering surfaces A, A of the lower end surface of the post 5 are bonded to the substrate 2 by the solder 3. It is connected to electrode 2b.

In the above embodiment, the wire connection part 5b is formed in a band shape, and the wire connection part 5b is arranged so as to cross the center of each end surface of the post main body 5b, so that two soldering surfaces A, A and one bonding surface B are formed, but the wire connection portion 5b may be provided in any manner.For example, as shown in FIG. Or rectangular wire connection part 5b
may be joined together.

Further, the post body 5a may have any shape as long as it can distinguish between the end surfaces 5A and 5B on which the soldering surface A and the bonding surface B are provided and the side surface on which these surfaces A and B are not provided, and is limited to a prismatic shape. It's not something you can do. For example, as shown in FIG. 6, the post body 5a may be formed into a cylindrical shape. If the post body 5a is formed into a prismatic shape, it should be formed into a flat shape whose thickness is sufficiently small compared to the vertical and horizontal dimensions, so that both end surfaces 5A and 5B can be distinguished from other side surfaces (the post 5 direction identification).

If the shape of the post body 5a is cylindrical as shown in FIG. 6, the orientation of the post can be reliably identified. In this case, the wire connection portion 5b can also be formed in a band shape as in the example shown in FIG.

In the above explanation, nickel and aluminum were mentioned as the metal forming the post body 5a and the metal forming the wire connection part 5b, respectively.
Of course, the present invention can be similarly applied to cases where other different types of metals are combined.

Effects of the Invention As described above, according to the present invention, since both the bonding surface and the soldering surface are formed on both end surfaces of the post, it is not necessary to distinguish between the soldering surface and the bonding surface of the post. This has the advantage of improving the efficiency of wire bonding work.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of wire bonding using a conventional wire bonding post, Fig. 2 is a perspective view of a conventionally used wire bonding post, and Fig. 3 is an example of the present invention. FIG. 4 is a perspective view showing the wire bonding post of the example. FIG. 4 is a sectional view showing an example of wire bonding using the wire bonding post of the same example. FIGS. FIG. 7 is a perspective view showing another different embodiment of the invention. 1...Semiconductor element chip, 2...Substrate, 2
a, 2b... Conductive part, 3... Solder, 4... Wire, 5... Post for wire bonding, 5a...
...Post body, 5b...Wire connection part, 5A, 5
B... End face of post, A... Soldering surface, B...
Bonding side.

Claims (1)

[Claims] 1. A wire bonding post comprising a post main body made of a first metal that can be soldered, and a wire connection part made of a second metal capable of bonding a wire and integrally joined to the post main body, The wire connection portion is formed to have a surface area smaller than the surface area of both end surfaces of the post main body, and is disposed on both end faces of the post main body, and has both a soldering surface and a bonding surface on each end surface of the post. A wire bonding post characterized in that a wire bonding post is formed.