JPS6222467A - Manufacture of lead frame - Google Patents

Abstract

PURPOSE:To eliminate complicated Al sectional evaporation process, to enable lead frames to be massproduced, and to reduce the cost, by forming preliminarily a metal thin film all over one side of a metal substrate, and by etching selectively the metal thin film. CONSTITUTION:After an Al evaporated film 14 with a predetermined thickness is formed on a metal substrate 11, in order to remove unrequired Al evaporated film 14 portions a resist film 12 is coated on the Al evaporated film 14, is exposed through a photo mask, and is developed. Thereafter, a mask pattern of the resist film 12 is formed, and the Al evaporated film 14 is etched with a sodium hydroxide solution to remove the resist film 12. In order to etch the metal substrate 11 in the lead frame shape, resist films are coated on both sides, are exposed through photo masks 16 for a lead frame pattern, and are developed. In this case, the photo masks 16 cover the Al evaporated film 14 including the side sections. Next, using the resist film 15 as a mask, the metal substrate 11 is etched with a ferric chloride solution into a lead frame pattern, and then the resist film 15 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a lead frame, and particularly to a method for manufacturing a lead frame for a semiconductor device using an etching method.

〔overview〕

The present invention is a method for manufacturing a lead frame for a semiconductor device using an etching method, in which a metal thin film of A1, for example, necessary for later forming a bonding part is formed on the entire surface of one side of a metal substrate, and a predetermined pattern is formed by etching. By including the steps of forming the patterned metal thin film, including the side surfaces thereof, with a resist and etching the metal substrate into the pattern of the lead frame, the complex partial metal vapor deposition process required in the past is eliminated. This made mass production possible.

[Conventional technology]

Conventionally, when manufacturing a lead frame by etching, a metal substrate of a fixed length is used, as shown in FIGS. 4(a) to (f).
It was manufactured using the photo-etching method shown in . That is, a resist film 2 is coated on both sides of the metal substrate l shown in FIG. 4(a) as shown in FIG. 4(bl), and exposed and developed through a photomask 3 as shown in FIG. 4(C). By doing this, a mask consisting of the resist film 2 is formed as shown in FIG.
A lead frame pattern is formed as shown in the figure (el),
Lead frames were manufactured by peeling off the resist film 2. This lead frame does not have the Al (aluminum) film required for wire bonding, so the normal part A
1 vapor deposition was being carried out.

[Problem that the invention seeks to solve]

The conventional lead frame manufacturing method described above is based on partial AI
An evaporation process is required, and this partial AJ evaporation process requires surface purification of the lead frame in order to carry out what has been removed from the lead frame, and partial Affi evaporation requires a special fixing jig that matches the lead frame. , required a mask and also required alignment of the lead frame. Therefore, it is impossible to process in large quantities, requires a large number of man-hours, and has the drawback of extremely high manufacturing costs.

An object of the present invention is to provide a method for manufacturing a lead frame, which eliminates the above-mentioned drawbacks and allows lead frames to be manufactured at low cost by an etching method without requiring a partial Al vapor deposition process.

[Means for solving problems]

The present invention provides a lead frame manufacturing method in which a lead frame is manufactured by etching a metal substrate. and a second step of selectively etching the metal substrate into a predetermined pattern with the metal thin film etched in the first step covered with a resist film including the side surfaces.

[Effect]

The present invention provides a metal thin film on one side of a metal substrate, such as A
A1 vapor deposited film is formed, and unnecessary portions of this Al vapor deposited film are A1 etched before the lead frame pattern etching process, and the Al vapor deposited film is protected from metal substrate corrosive liquid during lead frame pattern etching. Cover the side surface of the AFi vapor deposited film with a resist film so as to
Prevent l from being corroded. Thus, the complicated Ai! The partial vapor deposition process is eliminated, making it possible to mass produce lead frames and reducing costs.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1(a) to 1(kl) show partial cross-sectional views of main manufacturing steps of a lead frame according to an embodiment of the present invention.

Note that the lead frame here is for a sardine dip package. First, as shown in Figure 1(a), 42%Ni-Fe
An Al vapor deposition film 14 is formed to a predetermined thickness on a metal substrate 11 made of an alloy. Next, in order to remove unnecessary Al deposited film 14, a resist film 12 is applied to the surface of AI deposited film 14 as shown in FIG.
Expose and develop via 3.

After that, a mask pattern is formed using the resist film 12 as shown in FIG. 1+d), and the A1 deposited film 14 is etched with a sodium hydroxide solution to form the pattern shown in FIG. 1(e), and then the resist film 12 is removed. In order to etch the metal substrate 11 into the shape of a lead frame, the resist film 15 is etched as shown in FIG. 1(f).
is coated on both sides, exposed and developed through a runt mask 16 for a lead frame pattern as shown in FIG. 1(h). In this case, the photomask 16 is A
The side surfaces of the Il vapor deposited film 14 are also covered. Therefore, since the foot mask 16 needs to be accurately aligned, a resist film is placed around the metal substrate 11 to prevent misalignment by setting alignment bins around the metal substrate 11. Using 15 as a mask, the metal substrate 11 is etched into a lead frame pattern using a ferric chloride solution, as shown in FIG. 1(J). Thereafter, as shown in FIG. 1(G), the resist film 15 is removed to form a lead frame for a 16-pin sardine impedance package having an Al deposited film 14 (shaded area) as shown in FIG.

FIG. 3 is a plan view of a lead frame according to another embodiment of the present invention. According to the present invention, it is possible to easily manufacture such a flat lead frame for a cerdip package with leads extending in four directions.

Although the resist removal was performed twice in this embodiment described above, it is also possible to remove the resist once at the end. Furthermore, although the example of the lead frame for sardine puff packages has been given, it is obvious that the present invention can also be applied to lead frames for plastic puff cages.

〔Effect of the invention〕

As described above, the present invention eliminates the need for partial metal deposition on the lead frame by forming a metal thin film on the entire surface of a metal substrate in advance and selectively etching the metal thin film. In addition, single-sided, full-surface metal deposition on a metal substrate does not require special fixing jigs and masks unlike partial metal deposition on lead frames, and selective etching of the metal deposition film is similar to lead frame pattern etching. Since no jigs are required, it can be easily carried out in large quantities, resulting in low cost.

Therefore, the present invention has the advantage that lead frames can be manufactured in large quantities at low cost.

[Brief explanation of drawings]

FIGS. 1(a) to 1(k) are partial cross-sectional views showing the steps of manufacturing a lead frame according to an embodiment of the present invention. FIG. 2 is a plan view of a lead frame according to an embodiment of the present invention. FIG. 3 is a plan view of a lead frame according to another embodiment of the present invention. FIGS. 4(al) to (f) are partial cross-sectional views of the process order of a lead frame according to a conventional example. 1.11...metal substrate, 2.12.15...resist film, 3.13.16...・Photomask, 14...
AI vapor deposited film. Helmet 1 Example Tsuta 2 Group Example 'A3 Diagram

Claims (1)

[Claims] (1) In a lead frame manufacturing method in which a lead frame is manufactured by etching a metal substrate, a first step of forming a predetermined metal thin film on the entire surface of one side of the metal substrate and selectively etching this metal thin film into a predetermined pattern. and a second step of selectively etching the metal substrate into a predetermined pattern while covering the metal thin film etched in the first step with a resist film including the side surfaces. Production method.