JP3310468B2 - Pretreatment method for etching material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretreatment method for an etching material, and more particularly to a method suitable for etching a lead frame material.

[0002]

2. Description of the Related Art Generally, iron, stainless steel, iron-nickel alloy (42% Ni-remainder F
e), copper, copper alloy, etc. are subjected to a pretreatment such as degreasing-water-washing-acid-washing, and then coated with an aqueous or oily photosensitive resist. However, in this method, even if the degreasing and pickling are complete, the adhesion of the photosensitive resist is inferior, so that the swelling occurs on the end face after etching, or the swelling becomes round, and the specified size is obtained. Often times it is not possible.

By the way, if the surface of a material is oxidized,
It is said that since the hydroxyl groups (OH) in the resist and the oxygen in the oxide film are combined, the adhesiveness of the photosensitive resist is improved. Therefore, conventionally, various methods for forming an oxide film before applying a photosensitive resist have been proposed.

For example, a method in which a metal film is subjected to a heat treatment (Japanese Patent Application Laid-Open No. 5-44062), a method in which an iron oxide layer having a thickness of 95 to 1000 angstroms is formed on a surface of an iron-based metal by a heat treatment (Japanese Patent Application Laid-Open No. Sho 63) -489 publication),
Heat treatment in an oxidizing atmosphere to form a thin metal oxide film on the surface of the metal film (JP-A-49-11184)
No. 0), one using an aqueous solution of an alkali sulfonic acid, a surfactant and an oxidizing agent (JP-A-4-218686).
Japanese Patent Application Laid-Open No. Sho 55 (1994)], a steel material is immersed in a mixed solution of chromic acid and sulfuric acid to form an oxide film on the surface of the steel material.
No. 122876).

[0005]

However, the above-mentioned conventional method has the following disadvantages.

In the case of heat treatment as described above, since the width of the etching material is wide and long, a uniform film cannot be formed and etching becomes difficult. The use of an aqueous solution of (1) mainly focuses on cleaning the surface of the material, and since the treatment for improving the adhesiveness of the resist has not been performed, improvement in the adhesiveness of the photosensitive resist cannot be expected. Further, the method using a mixed solution of (1) and (2) is a general method for improving the corrosion resistance of a steel material. Since the film is formed quickly, the film on the surface becomes too thick, and is not suitable as a pretreatment for a steel material for etching.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art by improving the uniformity of the photosensitive resist by forming a thin oxide film uniformly on the surface, and to finish the etching processing dimensions with high precision. It is an object of the present invention to provide a method for pre-treating an etching material, which is possible.

[0008]

A lead frame according to the present invention is provided.
Pretreatment methods use material, characterized in that before applying the photosensitive resist on the lead frame material to form an oxide film using a mixture of chromic acid and phosphoric acid Ridofu
In the method for pre-treating a material for lame, the composition of the mixture of chromic acid and phosphoric acid has a chromic acid concentration of 10 to 80 g /
l, there is provided a pre-treatment method of the lead frame material, which is a phosphoric acid concentration 40 to 100 g / l.

[0009]

When an oxide film is formed using a mixed solution of chromic acid and phosphoric acid, the film is formed slowly, so that the oxidizing property is slow and an oxide film on the order of angstroms is formed uniformly. Therefore, the adhesion of the photosensitive resist to the etching material can be greatly improved without impairing the etching property, and the etching is facilitated.

The etching material of the present invention includes iron, stainless steel, iron-nickel alloy (42% Ni-remaining Fe).
There are copper, copper alloy and the like. The photosensitive resist may be aqueous or oily.

As a result of various studies on the composition of a mixture of chromic acid and phosphoric acid used in the present invention, the chromic acid concentration was 10 to 80 g / l and the phosphoric acid concentration was 40 to 100 g / l.
l, the temperature of the working solution is from room temperature to 50 ° C, and the processing time is 30
It has been found that it is preferable to use in the range of up to 120 seconds. The optimal conditions within this range of use are chromic acid 5
0 g / l + phosphoric acid 80 g / l, liquid temperature 30 ° C., processing time 30 seconds.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pretreatment method for an etching material according to the present invention will be described below. FIG. 1 is an overall view of a pretreatment step when a lead frame material is used as an etching material. The lead frame material unwound from the material unwinder 1 is degreased, collected, and washed with water through the accumulator 2.
Where it is degreased, recovered and washed with water. further,
Pickling-recovery-Send to pickling unit 4 to pickle, recover and wash with water.

Then, it is sent to an oxidation-recovery-rinse device 5 constituting a pretreatment device which is a main part of the present embodiment. The oxidation treatment in the oxidation-recovery-washing device 5 is performed by forming an oxide film on the surface of the lead frame material using a mixed solution of chromic acid and phosphoric acid.

The lead frame material on which the oxide film has been formed is sent to a photosensitive resist coating machine 7 via a water heater 6 where the photosensitive resist is coated. After the application, the resist is sent to a hot-air dryer 8 to dry the resist, and a material take-up device 9 winds up the lead frame material with the resist.

The lead frame material with resist wound by the winder 9 is then exposed and etched using a mask pattern of a predetermined shape to form a lead frame of a predetermined shape.

As described above, since the oxide film is formed before the application of the photosensitive resist to the lead frame material, the adhesion of the photosensitive resist is improved. Further, since a mixed solution of chromic acid and phosphoric acid is used to form an oxide film, the oxidizing property is slow and an oxide film of the order of Angstrom is formed uniformly.

As a result, the etching is improved, and the yield of the etched product is greatly improved. Further, the dimensional accuracy of the lead frame is significantly improved. Furthermore, the appearance of the product is improved, and chipping of leads, pinholes and the like are eliminated. In addition, since the treatment with a mixed solution of chromic acid and phosphoric acid is performed before the application of the photosensitive resist, deterioration of the photosensitive resist is eliminated.

(Specific Example) 42% N with 0.15 mmt thickness
Using the remaining Fe alloy strip, i-160
When manufacturing the lead frame of the pin, a photosensitive resist was applied by applying the method of the above embodiment to the pretreatment of the lead frame material. The conditions are as follows.

Degreasing (30 g / l caustic soda, soaked at 40 ° C., 30 seconds) ↓ Pickling (10 g / l hydrochloric acid, room temperature, soaked for 30 seconds) ↓ Oxidation treatment (30 g / l chromic anhydride + 50 g / l phosphoric acid, 50 ° C.) , 30 seconds immersion) For comparison, degreasing → pickling →
A photosensitive resist was applied by applying a conventional method of oxidation treatment (20 g / l chromic anhydride + 600 g / l sulfuric acid, immersion at 85 ° C. for 30 seconds). Table 1 shows the results of the adhesion, dimensional accuracy, yield, and appearance of the resist applied to the alloy strip by applying these two methods.

[0020]

[Table 1]

As is apparent from Table 1, the adhesiveness of the resist was measured by using a cellophane peel test. Although stripping of the resist was recognized in the conventional method, all the samples in the present embodiment were sound.

The dimensional accuracy of the round hole and the lead width is ± 0.02 mm in this embodiment, but ± 0.05 mm in the case of the conventional method. there were.

As is clear from Table 1, the yield is 97% in the present embodiment, whereas it is 7% in the conventional method.
0%, which indicates that the method of this example is significantly superior. In the case of the present example, the appearance of the lead shape was linear, and almost no "undulation", chipping, or pinhole was recognized, whereas in the case of the conventional method, these were recognized.

[0024]

According to the present invention, the chromic acid concentration is 10 to 8
Since the oxide film is formed using a mixture of 0 g / l and phosphoric acid concentration of 40 to 100 g / l, a thin oxide film can be uniformly formed on the surface, and the adhesion of the photosensitive resist is improved. However, the dimensional accuracy of the lead frame material can be significantly improved.

[Brief description of the drawings]

FIG. 1 is an overall view of a lead frame material pre-etching process for explaining an embodiment of the etching material pre-treatment method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Material unwinder 2 Accumulator 3 Degreasing-collection-washing device 4 Pickling-collection-washing device 5 Oxidation-collection-washing device 6 Water heater 7 Photosensitive resist coating machine 8 Hot air dryer 9 Material winder

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroshi Yamada 3-1-1, Sukekawa-cho, Hitachi City, Ibaraki Prefecture Inside the wire plant of Hitachi Cable Co., Ltd.

Claims (2)

(57) [Claims] 1. A lead frame material , wherein an oxide film is formed using a mixed solution of chromic acid and phosphoric acid before applying a photosensitive resist to the lead frame material.
In charge of the pre-processing method, leads to the composition of the mixed solution of the chromic acid and phosphoric acid, chromic acid concentration 10 to 80 g / l, characterized in that the phosphoric acid concentration 40 to 100 g / l
Pretreatment method for frame material . 2. The method for pretreating a lead frame material according to claim 1, wherein the mixed solution of chromic acid and phosphoric acid is used at room temperature to 50 ° C. for a processing time of 30 to 120 seconds.