JPH0139655B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION For example, when manufacturing a semiconductor lead frame whose surface is partially coated with aluminum, the present invention eliminates the need for composite metal strips in which aluminum is vapor-deposited or clad in stripes on the entire surface or in the longitudinal direction. This invention relates to a continuous partial etching method for long strips that can be applied to cases where aluminum is partially removed.

Traditionally, in the manufacture of lead frames used in the assembly of transistors and integrated circuits (ICs), or lead frames for electrical terminals, composite metal strips, in which parts of base metal strips are coated with dissimilar metals by coating or vapor deposition, have been used. Used as a material. As dissimilar metals, metals such as gold, silver, copper, and aluminum are mainly used, but due to the high price of precious metals, there is a tendency to change from gold and silver to cheaper ones such as copper and aluminum. There is also a tendency to change from full-surface or striped coverage to spot coverage, limiting the area to functional or necessary areas.

Currently, such composite metal strips are often made by coating a base metal strip with dissimilar metals in the form of stripes or spots, and in this case, the dimensional accuracy of the coated dissimilar metals, including the thickness, is extremely severe. Things are becoming more and more demanded.

However, it is extremely difficult to coat and bond dissimilar metals onto a base metal strip with high precision in the form of spots, and apart from plating, methods such as coating or vapor deposition are used to coat dissimilar metals onto a base metal strip. After the entire surface is coated, unnecessary portions of the dissimilar metal are generally removed partially by a printing-etching method.

By the way, in the printing-etching method, after applying etching resist ink to the necessary parts of the composite metal strip, the whole is immersed in an etching liquid. , etching, and ink removal, and each step requires maintenance and inspection of the equipment based on strict quality control, making the time required for each step of the composite metal strip irregular. It is extremely difficult to do this on a line, and it is common to do it on multiple lines.

Therefore, in the case of the above-mentioned printing-etching method, operations such as winding up, carrying out, and rewinding the composite metal strip are always required during the process, but these moving operations reduce work efficiency and reduce the number of composite metal strips. There is a problem in that the yield rate and quality deteriorate due to damage to the metal strip and adhesion of dust and the like.

Furthermore, in the case of the printing-etching method, there are problems in terms of working environment and economy due to the use of ink.

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and by adopting a method of etching using a mechanical mask in a closed room, there is no need to apply ink, etc., and the etching can be performed continuously on one line. It is an object of the present invention to provide a method for continuous partial etching of a long strip, which can significantly improve quality and manufacturing efficiency since it can be etched.

The continuous partial etching method of the present invention includes the steps of preparing a long strip of coated metal strip to be etched, and intermittently moving the long strip through a sealed chamber for etching. ,
The step of arranging the mechanical mask in the sealed chamber so that it can come into contact with and separate from the long strip, and when the long strip is stopped in the sealed chamber, the mechanical mask in the sealed chamber is placed in the long strip. Etching is carried out by contacting the parts of the strip that do not need etching and at the same time bringing other parts that need to be etched into contact with the etching solution. After the etching process, the etching solution is discharged from the sealed chamber and the mechanical mask is attached to the long strip. This method is characterized by comprising a process of moving the long strip toward and away from the body, and a process of repeatedly performing the etching process by moving the elongated strip intermittently.

In the present invention, by intermittently moving the long strip and etching it using a finite length mechanical mask, it is possible to eliminate the need for applying ink, etc. Since the etching process can be performed continuously on one line, the etching process can be performed efficiently and the quality can be improved.Furthermore, the etching process can be performed by placing the mask in a closed chamber. This prevents the etching solution from scattering and improves the working environment, making it possible for the first time to carry out continuous etching on an industrial scale.

The mechanical mask is used to prevent the surface of the elongated strip in contact with the etching solution, and the following methods can be considered as methods of masking using the mechanical mask.

(1) A method using a mechanical mask made of a soft elastic material such as rubber or resin material, or a rigid material such as metal, and pressing it against the portion of a long strip that does not require etching.

(2) In addition to the method described in (1) above, a method of airtightly preventing etching liquid from entering areas where etching is not required using a gas such as air.

Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

1 and 2 are a sectional view and a top view of an etching apparatus used in the present invention. In these figures, the elongated strip 1 is a composite metal strip made of a base metal made of, for example, an iron-nickel alloy and one entire surface of which is coated with aluminum. The elongated strip 1 is intermittently moved through a closed chamber 4 for etching, and a portion thereof is located within the closed chamber 4. The sealed chamber 4 consists of a base 2 and an upper lid 3, and two mechanical masks 5 are disposed therein together with a part of the elongated strip 1. The mechanical mask 5 has a main body part 6 and a tip part 1 as shown in FIG.
4, and in the case of FIG. 3, the tip 14 is made of a soft elastic material such as rubber about 7 mm square. The main body part 6 of the mechanical mask 5 is provided so as to be slidable while maintaining the straightness of contact with the elongated strip 1 by the upper cover 3. Long strips 1 of mechanical mask 5
The air cylinder 7 makes contact with and separation from the material. In order to maintain a high degree of airtightness in the sealed chamber 4, a packing 8 is arranged as necessary, and an air cylinder 10 is installed in accordance with the movement of the elongated strip 1.
It is becoming more liberating.

Next, in the etching process, as shown in FIG. Etching liquid is injected or press-fitted from 11, and during the etching process, the etching liquid is discharged from the outlet 12 provided in the upper lid 3 in order to fill the space 9 in the sealed chamber 4 with the etching liquid. base 2
The etching process is carried out by discharging the etching solution from an outlet 13 provided in the. In the case of this example, by setting the pressure of the mask 5 against the aluminum-coated elongated strip 1 to 3 to 5 kgf, extremely good etching accuracy could be obtained.

In this embodiment, the number of masks 5 is two, but this number can be increased as long as the manufacturing accuracy of the space structure of the sealed room 4 allows. A soft sheet material may be inserted between the base 2 and the elongated strip 1 so that the tip of the mask 5 uniformly contacts the elongated strip 1. Further, after the etching is completed, cleaning can be performed using cleaning water using the space 9 of the sealed chamber 4 of this apparatus.

FIG. 4 shows another embodiment of the present invention, in which the tip 15 at the end of the main body 6' of the Max is made of a rigid body such as stainless steel, and the inside of the main body 6' is a hollow part that communicates with the outside. 16. According to the main body part 6' of this mask,
During the etching process, 0.05
By applying an internal pressure of ~0.9 atmospheres (gauge pressure), it is possible to reliably prevent the etching solution from entering the mask, and as a result, an etched surface with extremely clear boundaries can be obtained. 17
is an aluminum coating provided on the elongated strip 1.

FIGS. 5 and 6 each show an example of a product etched according to this embodiment. That is, according to FIG. 5, the main body portion 6 or 6' of the mask is brought into contact with the elongated strip 1 made of an aluminum-coated metal strip, and the etching process is performed, leaving the necessary aluminum coating portions in spots. This figure shows an IC lead frame patterned using the following methods. FIG. 6 shows an IC lead frame formed by punching out the lead frame with a press.

As described above, according to the etching method of the present invention, the etching process is performed using a finite-length mechanical mask while moving the long strip intermittently, thereby eliminating the need for applying ink, etc. In addition, the mechanical mask method allows the etching process to be performed continuously on one line, making it possible to perform the etching process effectively and improve quality. By arranging the mask and performing the etching process, it is possible to prevent the etching solution from scattering, thereby improving the problem of the working environment, and making it possible to perform the etching process on a long strip for the first time industrially and economically. Its industrial value is extremely significant compared to the conventional printing-etching method.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an etching apparatus according to an embodiment of the present invention, FIG. 2 is a top view of the etching apparatus shown in FIG. 1, FIG. 3 is a front view and bottom view of a mechanical mask, and FIG. The cross-sectional view and bottom view of the target mask, and FIGS. 5 and 6 are front views of the IC lead frame manufactured by etching, respectively. 1: Long strip, 2: Base, 3: Upper lid, 4: Sealed chamber, 5: Mechanical mass, 6: Main body, 7,1
0: Air cylinder, 8: Packing, 9: Closed space, 11: Inlet, 12, 13: Outlet.

Claims (1)

[Claims] 1. A step of preparing a long strip of coated metal strip to be etched, and intermittently moving the long strip through a sealed chamber for etching, and placing a mechanical mask inside the sealed chamber. The process of arranging the long strip so that it can come into contact with and separate from the long strip, and when the long strip is stopped inside the closed chamber,
Etching is carried out by bringing the mechanical mask in a sealed chamber into contact with the parts of the elongated strip that do not need to be etched, and at the same time bringing the other parts that need to be etched into contact with the etching solution, and after the etching,
A long strip characterized by comprising a step of discharging the etching solution from the sealed chamber and moving the mechanical mask toward and away from the long strip, and a step of repeating the etching step by intermittently moving the long strip. Continuous partial etching method of the ulnar body.