JPH0541549Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement of a spool for winding a bonding wire for a semiconductor device.

[Prior Art] Generally, bonding wire for semiconductor devices (hereinafter simply referred to as wire) used as a material for electronic components is transported and stored while being wound around a spool. A known method for winding the wire is to tightly wind the wire by making the winding pitch the same as the diameter of the wire. However, when multiple layers are wound using this method, the wires in the upper layer may get stuck between the wires in the lower layer, which may cause trouble when the wire is paid out from the spool. Therefore, conventionally, a method called cross winding has been adopted in which the winding pitch is increased to leave a gap between the wires, and the wires in the upper layer are wound so as to cross over the wires in the lower layer. Conventionally, the spool used for such cross winding has flanges formed at both ends, and the winding drum around which the wire is wound has a circular cross section, and the diameter of the winding drum is constant. things are used.

By the way, the wire is extremely thin with a diameter of 25 to 50 μm and is soft, so it is easily damaged and broken. For this reason, conventionally, the surface roughness of the winding drum of the spool is set to 0.2 to 0.4 Ra to prevent the first layer of wire wound around the winding drum from being damaged.

[Problems to be solved by the invention] However, in the above-mentioned conventional spool, the wound wire may loosen during transportation, etc.
In such cases, there was a problem that the wires would slip down and get tangled. That is, the wire is wound around the winding drum with a predetermined tension applied thereto, and this tension creates a frictional force between the wire and the winding drum, so that the wire is held on the spool. However, in the above-mentioned spool, since the surface of the winding drum is extremely smooth, the frictional force generated between the winding drum and the wire is small, and as a result, the entire wire tends to shift in the axial direction of the spool and become loose. be.

To deal with this, it is possible to adjust the winding tension, but in recent years, semiconductor devices have become more highly integrated and smaller, and the diameter of the wire used in semiconductor devices has also tended to become thinner. As a result, the yield strength of the wire tends to decrease accordingly. Therefore, if the winding tension is increased so that the tension exceeds the yield strength of the wire, the wire may be deformed or its physical properties may change, which is undesirable.

This idea was made in view of the above circumstances,
Not only can it prevent the wire from breaking, but it can also prevent the occurrence of slack without deforming the wire or changing its physical properties. It is an object of the present invention to provide a spool for bonding wire of a semiconductor device that can be bonded smoothly.

[Structure of the present invention] The bonding wire spool of the semiconductor device of this invention is constructed by setting the surface roughness of the drum around which the wire is wound to 0.5 to 2 Ra. This surface roughness value was obtained through numerous experiments as the most suitable value for achieving the purpose of this invention, and is based on the frictional force required between the wire and the winding drum of the bonding wire spool. 0.5Ra is set as the lower limit to give the wire, and 2Ra is set as the upper limit to prevent damage to the wire.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. FIG. 1 is a perspective view showing a bonding wire spool (hereinafter simply referred to as spool in this embodiment) of a semiconductor device according to an embodiment. The spool shown in this figure has flanges 2, 2 formed at both ends of a cylindrical main body 1, and a winding drum 3 formed in the middle of the flanges 2, 2. Surface roughness is 0.5~2Ra
It is set to . As shown in FIG. 2, such a spool is made by winding the wire 4 around the winding drum 3 in one layer with large intervals, and then winding the wire 4 in multiple layers so that the wire 4 in the upper layer crosses the wire 4 in the lower layer. It is beginning to be used. In this spool, the winding drum 3
Since the surface roughness of the wire is set to 0.5 to 2Ra, it is possible to prevent wire damage and loosening.

Conventionally, it has been thought that the surface roughness of the winding drum needs to be as small as possible in order to avoid damaging the wire. However, as a result of intensive research by the inventors of the present invention, it has been found that if the surface roughness of the winding drum is within the range of 0.5 to 2Ra, the wire will be less likely to be damaged, and the necessary frictional force between the wire and the winding drum can be obtained. I gained the knowledge that it is possible. In other words, whether the wrapped wire is easy to break or not,
It is affected by conditions such as the surface roughness of the winding drum, the winding tension, the winding pitch, and the total weight of the wire wound. Therefore, the present inventors varied these various conditions and vibrated the spool around which the wire was wound in the axial direction for a certain period of time, and determined through experiments the frequency at which the wire broke.

Figure 3 is a diagram showing the frequency of wire breakage when the surface roughness is changed under the conditions that the winding pitch is 6 mm, the total weight of the wire wrapped is 12 g, and the winding tension is 1 g, 2 g, and 3 g, respectively. be. Also, in Figure 4, the winding tension is 2g,
The total weight of the wire is 12g, the winding pitch is 3mm, 6mm, and 9mm, respectively, and Figure 5 shows the above conditions under the conditions that the winding pitch is 6mm, the winding tension is 2g, and the total weight of the wire is 6g, 12g, and 18g, respectively. This shows the results of a similar experiment. The experimental sample used was a wire with a diameter of 20μ wound around a winding drum in five layers. From these figures, it can be seen that even if the winding tension, winding pitch, and total weight of the wire change, the frequency of wire breakage sharply decreases when the surface roughness is 0.5Ra or more.

Furthermore, whether or not the wound wire is susceptible to damage is influenced by the surface roughness of the winding drum as well as the magnitude of the winding tension. Therefore, the inventors of the present invention changed these conditions, wound the wire around the winding drum, then let the wire out, and determined through experiments the frequency with which the wire was damaged. Figure 6 shows that the winding pitch is 6mm and the total weight of the wire is
12g, and the winding tension is 1g, 2g, and 3g, respectively, and is a diagram showing the frequency of damage to the wire when the surface roughness is changed. From this figure, it can be seen that even if the winding tension changes, the wire will not be damaged as long as the surface roughness of the winding drum 3 is 2a or less.

In this way, in the case of the above spool, the surface roughness of the winding drum 3 is set to 0.5 to 2Ra, so the wire 4 is less likely to be damaged, and the necessary friction between the winding drum 4 and the wire 3 is reduced. It can give you strength. Therefore, it is possible not only to prevent the wire 4 from being cut, but also to prevent the wire 4 from becoming loose without deforming or changing its physical properties. Unwinding work can be performed smoothly.

In addition, although the cross-sectional shape of the winding drum 3 is circular in the above embodiment, it is not limited to this shape, and the same effect as in the above embodiment can be obtained by using various shapes such as an ellipse. . Further, although the flange portions 2, 2 are formed at both ends of the main body 1, they may be formed only at one end.

[Effects of the invention] As explained above, in the bonding wire spool for semiconductor devices of this invention, the surface roughness of the drum around which the wire is wound is set to 0.5 to 0.5.
Since it is set to 2Ra, the wire is less likely to be damaged and can provide the necessary frictional force between the winding drum and the wire. Therefore, not only can the wire be prevented from breaking, but also the generation of slack can be prevented without deforming the wire or changing its physical properties, making it easier to carry, store, or unwind the wire. The effect is that the process can be carried out smoothly.

[Brief explanation of the drawing]

1 to 6 are views showing one embodiment of the present invention, in which FIG. 1 is a perspective view showing a spool, FIG. 2 is a side view showing a state in which the wire is wound around the spool, and FIG. 3 is a diagram showing an embodiment of the present invention. 5 to 5 are diagrams showing the relationship between the surface roughness of the winding drum and the frequency at which the wire breaks, and FIG. 6 is a diagram showing the relationship between the surface roughness of the winding drum and the frequency at which the wire is damaged. 3... Winding trunk, 4... Wire.

Claims (1)

[Scope of utility model registration request] The surface roughness of the winding drum around which the wire is wound
0.5~2Ra (Ra indicates center line average roughness)
A spool for bonding wire for semiconductor devices, characterized in that it is set to: