JPS6237953A - Manufacture of lead frame - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is particularly applicable to the production of 1' frames used in semiconductor devices, etc., in which an aluminum film is deposited on the surface of a lead frame (hereinafter abbreviated as A1 deposition). It is known from a lead frame manufacturer θ that in a method, 1% aluminum skin is deposited on the surface of a lead frame shaped by photoetching to improve wire bonding.

To explain in more detail the method for manufacturing the -1 frame, first, the photo-etching process is performed as follows. For example, a flat plate of 42 alloy material with a thickness of 0.25 mm is prepared, and the surface of this flat plate is rolled over, a resist layer is coated and dried, and a lead frame pattern is baked and developed. Etching is performed with an etchant containing this l&ferric chloride solution as a main component, washing with water, peeling off the resist l-film, washing with pure water, etc., followed by draining and drying.

Then, a substrate (jig) for performing Al vapor deposition is attached to the main parts of the lead frame obtained in this way, including the wire bonding area, and A7! Perform vapor deposition.

(Problems to be Solved by the Invention) However, the conventional lead frame manufacturing method described above has the following problems.

In other words, the surface of the LEET frame, which has been subjected to photoetching into the shape 4J-F, is in direct contact with the etching solution, lettuce peeling liquid, etc. due to the WesoE process, and foreign matter remains. In order to remove these substances, cleaning and further washing with pure water are performed after each process.

Even if such cleaning is performed, residual foreign matter cannot be completely removed, and when washing with water, deterioration (discoloration) such as rust may occur depending on conditions such as washing time and drying method, and when washing with pure water, However, in order to prevent the lead frame from being damaged by the time the cleaning water is poured, the method of draining is limited, resulting in partially incomplete draining, resulting in stains and the like. Furthermore, liquid pools and foreign matter remain in the microscopic pinholes and the like that occur during etching7, and the reality is that there is no means to effectively prevent this.

Incidentally, this kind of problem causes Ap deposits in post-processing, such as lead frames, and causes blistering of the aluminum film and poor adhesion for semiconductor device parts that require high precision and high purity. etc., resulting in fatal defects.

(Means for Solving the Problems) The present invention is a lead frame manufacturing method that solves two problems in the conventional methods, and can be achieved by the following means.

In other words, as shown in the drawing, A
In a method for manufacturing a lead frame in which Affi deposition is performed in the vapor deposition process, the etching solution culms A and A are
P vapor deposition Z is characterized by including a cleaning step B in which the lead frame is left in an atmosphere containing hydrogen at high temperature for a certain period of time.

(effect) Next, the operation of the present invention will be explained.

In the above-mentioned purification step B, deterioration such as rust on the lead frame is recovered by the reducing action of hydrogen, and attached foreign matter is removed by combustion and vaporization at high temperatures. In this case, due to the trial process, there is no subsequent deterioration due to moisture or residual foreign matter, and complete purification can be achieved.

(Example) Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

The drawings are process diagrams of a method for manufacturing a lead frame according to the present invention.

Note that the steps (A) to (D) shown in the drawings indicate the main steps for manufacturing a lead frame, and in this process, the present invention particularly adds a cleaning step B or replaces it with another cleaning step, etc. It is characterized by:

Next, each step will be sequentially explained according to the figure.

[Photoetching process A]

As described above, a flat plate made of 42 alloy material or the like is cleaned, a resist film is applied and dried, and a lead frame pattern is baked and developed.

Thereafter, etching is performed with a corrosive solution containing ferric chloride solution as a main component, and the resist film is removed and cleaning is performed to complete the shape of the lead frame.

[Purification process B]

The surface of the lead frame is cleaned by a cleaning process provided in accordance with the present invention.

Although the cleaning in the photoetching step A described above is not complete, most of the foreign matter is removed. However, since fine residual foreign matter and surface deterioration cannot be removed, the surface is completely cleaned in step B.

This step B is carried out by leaving the lead frame in an atmosphere under the following conditions.

Temperature: Approximately 500° C. Time: Approximately 10 minutes Flowing gas (H hydrogen gas): A mixed gas of N, (nitrogen gas)-11 is flowed.

It has been confirmed that a temperature of about 400° C. or higher is sufficiently effective. Further, a mixed gas may be used as the flowing gas, or another inert gas may be mixed therein.

In this case, mixing of oxygen should be avoided in order to cause a reduction effect.

[Board mounting is step C]

The surface is purified by the above T culm B, and the area where A1M should be attached is exposed on a part of the frame, and the rest is covered.
! It is attached to a predetermined board (jig) such as "

This ensures that Aρ is deposited only on the necessary areas in consideration of areas necessary for wire bonding, glass sealing, and the like.

[Al! Stem attaching step D] In step C described below, an A1 film of about 3 μm is applied to the frame partially masked by the substrate or to a part of the frame using a film forming method such as a vacuum evaporation method to complete a desired lead frame.

Although the embodiments have been described in detail above, the present invention is not limited to such embodiments, and the detailed configuration,
Any changes may be made in the procedures, processing methods, numerical values, etc. without departing from the spirit of the present invention.

(Effects of the Invention) As described above, in the lead frame manufacturing method according to the present invention, between the photolithography process and the aluminum lining process,
Since this process includes a purification process in which the lead frame is left in an atmosphere containing hydrogen at high temperatures for a certain period of time, it is possible to completely remove foreign matter and deterioration from the lead frame before the aluminum deposition process. Failures caused by such problems, such as peeling and blistering of the aluminum vapor deposited film (poor adhesion), and fatal defects in the semiconductor device W manufacturing process such as wire bonding defects can be significantly reduced. In particular, since it is a dry process, stable processing can be easily performed.

[Brief explanation of drawings]

The drawings are process diagrams showing a method for manufacturing a lead frame according to the present invention. In addition, in the drawings, A... Esoching process, B... Purification process, D... Aρ stem-attaching process.

Claims (1)

[Claims] 1. In a lead frame manufacturing method in which an aluminum film is deposited on the surface of a lead frame formed by photo-etching, between the photo-etching step and the aluminum vapor deposition step, the lead frame is placed in an atmosphere containing hydrogen at high temperature for a certain period of time. A method for manufacturing a lead frame, comprising a purification step of leaving the lead frame alone.