JPH1161695A - Antirust paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antirust paper suitable for a lead frame made of a copper material by impregnating a paper having low chlorine ion and sulfate ion contents with a benzotriazole-type antirust agent. SOLUTION: The objective antirust paper effective for suppressing the generation of rust caused by chlorine ion and sulfate ion and having improved antirust performance is produced by impregnating a benzotriazole-type antirust agent in a paper having a Bekk smoothness of >=60 sec on at least one surface and containing 5-18 ppm of chlorine ion and 30-50 ppm of sulfate ion in the paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rust-proof paper used for a metal sheet such as a lead frame, and more particularly to a rust-proof paper for a lead frame using a copper material for a lead frame.

[0002]

2. Description of the Related Art In general, rust prevention during storage and transportation of a lead frame is performed by alternately stacking rust-preventive papers and lead frames so that each lead frame is sandwiched between the rust-preventive papers. Even if kept in such a manner, discoloration and rust may occur due to oxidation of the copper material surface or the like depending on conditions during storage and transportation. That is, the rustproofing performance of the rustproof paper is not sufficient. Further, if the surface of the rust-proof paper is not rough, the pin tip is not fixed to the surface, and the arrangement of the pins may be disturbed or bent.

[0003]

SUMMARY OF THE INVENTION The present invention is to provide a rust-proof paper having improved rust-preventing performance so that discoloration and rust due to oxidation during storage and transportation as described above do not occur. . Another object of the present invention is to provide a rust-preventive paper that reduces the occurrence of disorder and bending of the pin arrangement due to the pin tip not being fixed to the surface of the paper.

[0004]

According to the present invention, there is provided a rust-preventing paper obtained by impregnating a paper with a benzotriazole-based rust-preventive agent, wherein the paper has a small amount of chloride ions and sulfate ions. It is rust-proof paper.

[0005] The present invention also relates to the rustproofing paper of the above invention, wherein the smoothness of at least one side of the paper is 60 seconds (Beck smoothness) or more (poor smoothness).

Further, the present invention relates to the rust-proofing paper of the above invention, wherein the chlorine-ion content is 5 to 18 ppm.

[0007] The present invention also relates to the rust-proofing paper of the above invention, wherein the amount of sulfate ions is 30 to 50 ppm.

Further, the present invention relates to the rust-proof paper of the above-mentioned invention, which is used for a lead frame using a copper material.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on one embodiment. FIG. 1 is a side view illustrating an embodiment of a state in which the rust-proof paper according to the present invention is used. As shown in the side view of FIG. 1, when rust-proof paper (2) is used,
In order to prevent more than one lead frame (3) from coming into direct contact and overlapping each other, one lead frame (3) and one rust-preventive paper (2) are alternately overlapped with each other. Paper is what is used. FIG. 2 is a plan view of this state. As shown in FIG. 2, the rust-proof paper (2) has a larger area than the lead frame (3). FIG.
The lead frame (3) is stored in a state of 6 pieces,
An example of transportation is shown. Figure 4 shows one piece (4)
FIG. 6 is a plan view of a minute lead frame (3). 5 is a pin tip.

[0010] Rust generated by the reaction of metal with oxygen, water, salt and the like is more likely to occur as the amount of chloride ions increases, and in the present invention, the amount of chloride ions in the paper is reduced as paper impregnated with a rust inhibitor. A small amount of paper is used, and for example, one having a chlorine ion content of 5 to 18 ppm in the paper is suitable. Similarly, rust is more likely to occur as the amount of sulfate ions increases, and in the present invention, paper having a small amount of sulfate ions in the paper is used as the paper impregnated with the rust inhibitor,
For example, those having a sulfate ion content of 30 to 50 ppm in paper are suitable.

When the rust preventive is a benzotriazole-based rust preventive, the stronger the acidity in the paper, the more the rust preventive power of the rust preventive is reduced. When using benzotriazole-based rust preventives and using paper with a small amount of chloride ions and sulfate ions in the paper, the rust preventive maintains its rust-preventive power and exhibits the original rust-preventive effect. Becomes As the benzotriazole-based rust preventive, benzotriazole, tolyltriazole, carboxybenzotriazole and the like are preferable.

When the surface of the rust-preventive paper has good smoothness, the pin tip (5) does not stick to the paper surface, and the arrangement of the pin tip (5) of the lead frame is likely to be disturbed or bent. It is. The occurrence of such disturbance or bending is caused when the material of the lead frame is a copper material or a copper alloy material (hereinafter simply referred to as a copper material) and the thickness thereof is, for example, 0.125 m.
The lead frame having a relatively small thickness is used for the lead frame having a thickness of about 100 m. The number of pins of the lead frame is, for example, about several hundred. This is likely to occur in a thin lead frame of about 125 mm.

This is because copper is a material having low rigidity and easy to be deformed by an external force as compared with 42 materials (Ni 42%, balance iron) which are widely used as a material of a lead frame.

Therefore, the present invention uses a rough paper having a poor surface smoothness in order to prevent the arrangement of pin tips (5) of a lead frame using a copper material from being disturbed or bent. Specifically, a paper is used in which the smoothness of at least one side of the paper is about 60 seconds (Beck smoothness) or more (poor smoothness).

Table 1 shows, as examples, the amounts of chloride ions and sulfate ions of the paper used in the present invention, and the compositions of the rust preventives. Also, as comparative examples, the amounts of the above-mentioned chloride ion and sulfate ion and the composition of the rust preventive agent in the conventional rust preventive paper are shown.

[0016]

[Table 1]

Table 2 shows the test results of the state of rust generation on the front and back surfaces of the copper material when the rust-preventing paper of the present invention was used, comparing the above Examples and Comparative Examples. In the present invention, under the test conditions of 40 ° C., 90%, 480 h, and 22 ° C., 60%, 480 h (atmosphere left), in the above example, there was almost no rust, and “no abnormality” was found. In the comparative example, rust was generated and "discolored", and the rust prevention performance of the example was superior to that of the comparative example.

[0018]

[Table 2]

The smoothness of the paper surface in the embodiment of Table 1 is as low as 4.6 seconds, because this surface is the surface coated with the rust preventive coating solution. Further, in the embodiment, since the pin tip is not disturbed or bent (not shown), it is sufficient if the smoothness of at least one side of the paper is 60 seconds (Beck smoothness) or more. It is shown that. Further, the rust preventive applied to the surface of the paper evaporates also from the back side of the paper and has a rust preventive effect.
The result of "No abnormality" was obtained for both the front and back surfaces in the example of (1).

[0020]

According to the present invention, the amount of chloride ions and the amount of sulfate ions in the rust-proof paper are suppressed to a low level.
Further, the generation of rust due to the influence of sulfate ions is suppressed, and the rust prevention performance is improved. In addition, when the rust inhibitor is a benzotriazole-based rust inhibitor, the amount of chloride ions and sulfate ions in the paper has been suppressed to a low level, so the rust inhibitor maintains its rust-preventive power and improves the rust-prevention of the original. The effect is exhibited, and the rust prevention performance is improved. Further, since the smoothness of the paper is set to an appropriate value, the occurrence of disorder and bending in the pin tip arrangement is reduced.

[Brief description of the drawings]

FIG. 1 is a side view illustrating an embodiment in which a rust-proof paper according to the present invention is used.

FIG. 2 is a plan view illustrating one embodiment of a state in which the rust-proof paper according to the present invention is used.

FIG. 3 is a view for explaining a state of a general lead frame in which a lead frame is composed of six pieces.

FIG. 4 is a plan view of a lead frame for one piece.

[Explanation of symbols]

 2: Rustproof paper 3: Lead frame 4: Lead frame for one piece 5: Pin tip

Claims (5)

[Claims] 1. A rustproofing paper comprising a paper impregnated with a benzotriazole-based rustproofing agent, wherein the paper has a small amount of chloride ions and a small amount of sulfate ions. 2. The rust-proof paper according to claim 1, wherein the smoothness of at least one side of the paper is 60 seconds (Beck smoothness) or more. 3. The rust-preventive paper according to claim 1, wherein said chlorine ion content is 5 to 18 ppm. 4. The rustproofing paper according to claim 1, wherein said chlorine ion content is 5 to 18 ppm. 5. The rust-proof paper according to claim 1, which is a rust-proof paper used for a lead frame using a copper material.