JP2000318080A - Conductive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate damage of an electronic component if an ion conductive material is used as a conductive agent or an antistatic agent, by forming an ion barrier layer containing an inorganic ion exchange material on a surface of a conductive layer or an antistatic layer provided at least on one side surface of a conductive sheet. SOLUTION: In a base material sheet 1 having a conductive layer 2, an ion barrier layer 3 containing an inorganic ion exchange material is formed on a surface of the layer 2. Then, as the sheet 1, for example, a sheet made of a general thermoplastic resin is used, and its thickness is, for example, about 0.2 to 1.5 mm. As a conductive agent, an electroconductive conductive agent may be used, and an ion conductive antistatic agent or a conductive polymer is particularly effective. Further, as a method for forming the barrier layer, a suitable film forming material is added to a mixing solvent together with an inorganic ion exchange material, the both are dispersed and dissolved to prepare a coating liquid, then the surface of the layer 2 is coated with the coating liquid and dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive sheet, and more particularly, to a conductive sheet useful for packaging various electronic parts.

[0002]

2. Description of the Related Art Conventionally, various electronic components such as ICs, capacitors, transistors, and LSIs are stored and transported in a container formed by molding a plastic sheet into a desired shape called a carrier tape or a carrier tray. Has been made. The electronic components and the like are easily broken by static electricity sparks or the like. Therefore, a conductive layer or an antistatic layer is formed on the plastic sheet used for the carrier tape or the like, or a conductive agent or an antistatic agent is mixed into the sheet to make the sheet conductive (antistatic). .

Examples of the conductive agent or antistatic agent include electronic conductive materials such as conductive carbon black, conductive metal oxides and metal powders, and surfactants having a quaternary ammonium group, polypyrrole, and the like. Polyurethane,
An organic material such as an ion conductive polymer obtained by doping a low molecular electrolyte into an acrylic resin or a polyester resin, or a polymer having a quaternary ammonium group introduced into these polymers is used. The above-mentioned electron conductive conductive agents other than conductive carbon black are generally expensive compared to their performance, and their use is not easy, and since conductive carbon black is strongly colored, Its use is often undesirable in appearance or in commercial terms.

[0004]

Unlike the electron conductive material, the ionic conductive agent is inexpensive and colorless in many cases, and because it is an organic substance, it is used as an antistatic agent. Easy and widely used. As a form of use, there are a form in which a conductive layer or an antistatic layer is formed on the surface of a plastic sheet as a base material sheet, and a form in which a plastic sheet is kneaded into a plastic and then formed into a sheet. Such a conductive sheet is easy and inexpensive to manufacture, but when the sheet is used for packaging electronic components, etc., the cation such as an alkali metal exhibiting conductivity or a counter ion thereof is used. An acid ion such as a halogen ion or a sulfate ion ion may be transferred to an electronic component, which may damage the electronic component, such as rust, and its use is subject to certain restrictions. Therefore, an object of the present invention is to provide a conductive sheet which does not damage electronic components even when an ion conductive material is used as a conductive agent or an antistatic agent.

[0005]

The above object is achieved by the present invention described below. That is, in the present invention, in a conductive sheet provided with a conductive layer or an antistatic layer on at least one surface, an ion barrier layer containing an inorganic ion exchanger is formed on the surface of the conductive layer or the antistatic layer. A conductive sheet, characterized in that an ion barrier layer containing an inorganic ion exchanger is formed on at least one surface of a conductive sheet and a conductive sheet containing a conductive agent and / or an antistatic agent. Provide a sheet.

According to the present invention, by forming an ion barrier layer containing an inorganic ion exchanger on the surface of a conductive sheet, contamination and damage to electronic components due to various ions migrating from the conductive sheet are prevented. be able to.
The present invention is not limited to the case where the conductive agent is an ionic conductive agent, but is of course effective when the conductive agent is an electron conductive conductive agent.

[0007]

Next, the present invention will be described in more detail with reference to preferred embodiments. FIG. 1 is a diagram illustrating one embodiment of the conductive sheet of the present invention, and FIG. 2 is a diagram illustrating another embodiment. In the conductive sheet of the example shown in FIG. 1, an ion barrier layer 3 containing an inorganic ion exchanger is formed on the surface of the conductive layer 2 in a base sheet 1 provided with a conductive layer 2. In the conductive sheet of the example shown in FIG. 2, an ion barrier layer 3 containing an inorganic ion exchanger is formed on at least one surface of a conductive sheet 4 containing a conductive agent.
In the example shown in FIG. 2, the ion barrier layers are formed on both sides of the conductive sheet, but the formation may be performed on only one side.

The plastic substrate sheet used in the present invention is made of, for example, a general thermoplastic resin such as a polyester resin such as polyethylene terephthalate, a polypropylene resin, a polycarbonate resin, a polystyrene resin, a polyvinyl chloride resin and a polyamide resin. The sheet is not particularly limited in thickness, but generally has a thickness of 0.1 mm.
It is about 2 to 1.5 mm.

In the example shown in FIG. 1, a conductive layer 2 is formed on at least one surface of the base sheet 1. The conductive agent used here may be the above-mentioned electron conductive conductive agent, but the present invention is particularly effective when the conductive agent is an ion conductive antistatic agent or a conductive polymer. . Examples of the antistatic agent or the conductive polymer include a surfactant or a polymer compound having a quaternary ammonium group, or a conductive polymer obtained by doping various polymer materials with an electrolyte. Hereinafter, the conductive agent and the antistatic agent are collectively referred to as a conductive agent, and the conductive layer and the antistatic layer are collectively referred to as a conductive layer.

The formation of the conductive layer is not particularly limited, and a known method can be used as it is. For example, if the conductive agent is not capable of forming a film by itself, such as a low molecular weight surfactant, a suitable film forming material, for example, acrylic resin, polyester resin, polyurethane resin, vinyl chloride or vinyl acetate A conductive layer is formed using a homopolymer, a copolymer with another monomer, or the like. Usually, a conductive agent and a film forming material are dispersed and dissolved in an appropriate solvent to prepare a coating solution, which is applied to a substrate sheet and dried to form a conductive layer.

On the other hand, when the conductive agent is a polymer conductive agent, it is not always necessary to use a film forming agent, but a film forming material is used to increase the adhesion to the base sheet and the strength of the film. Is preferred. The method for forming the conductive layer is the same as described above. The thickness of the conductive layer thus formed is not particularly limited, but is usually about 1 to 5 μm, and its surface resistance is in the range of about 10 ² to 10 ¹⁰ Ω / cm. In the case of the example shown in FIG. 2, an amount of a conductive agent that expresses a predetermined surface resistance value as described above is melt-kneaded in advance with the plastic material for a base sheet as described above, and this is formed into a sheet according to a conventional method. I just need.

In the present invention, an ion barrier layer 3 containing an inorganic ion exchanger is formed on the surface of the conductive sheet as described above. The barrier layer is formed on one surface of the base sheet in the example of FIG. 1, and is formed on both surfaces of the conductive sheet in the example shown in FIG. 2, but according to the intended use of the conductive sheet, In any case, it can be formed on one surface or both surfaces.

The inorganic ion exchanger used in the present invention is a known material, for example, “Mitsuo Abe, Japan Analys
t, 23, 1254 and 1561 (1974) ", JP-A-60-1685.
No. 41, JP-A-60-172353, JP-A-63-1452, JP-A-63-60112, JP-A-3-4940, JP-A-4-45854
And various treatments may be added to the inorganic ion exchanger described in these documents. Specifically, the product name “IXE” -100, 150,
200, 300, 400, 500, 550, 600, 8
00, 680, 700, 702, 900, 1000, 1
Under the trade names of 100, 1320, etc., for example, it can be obtained from Toa Gosei Chemical Industry Co., Ltd. or the like and used in the present invention. Particularly, inorganic ion exchangers such as magnesium-aluminum-based, antimony-based, and calcium-based are useful.

As a method of forming an ion barrier layer using the above-mentioned inorganic ion exchanger, a suitable film-forming material, for example, an acrylic resin, a polyester resin, a polyurethane resin, a homopolymer of vinyl chloride or vinyl acetate, or another polymer may be used. Film-forming materials such as copolymers with monomers, for example, alcohols such as isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, ketone solvents such as cyclohexanone, toluene, aromatic solvents such as xylene,
An inorganic ion exchanger is added to an amide solvent or a mixed solvent thereof together with an inorganic ion exchanger, and both are dispersed and dissolved to prepare a coating solution, which is applied to the surface of the conductive layer 2 or the conductive sheet 4 and dried to form a coating solution. do it.

The content of the inorganic ion exchanger in the formed ion barrier layer is preferably in the range of about 10 to 30 parts by weight per 100 parts by weight of the film-forming material. If the concentration of the inorganic ion exchanger is too low, a sufficient ion barrier is obtained. On the other hand, if the amount of the inorganic ion exchanger is too large, a sufficiently tough film is not formed, the inorganic ion exchanger may fall off, and the electronic components may be contaminated. or,
The thickness of the formed ion barrier layer is preferably about 1 to 3 μm. If the ion barrier layer is too thin, sufficient barrier properties cannot be obtained, and when forming the conductive sheet into an appropriate shape, the barrier layer becomes thin at corners and the like, and the barrier properties are partially reduced. On the other hand, if the ion barrier layer is too thick, the performance is not particularly improved, which is disadvantageous in cost.

The conductive sheet of the present invention obtained as described above is useful as a raw material for various packaging materials such as carrier tapes and trays for various electronic components. To form a desired shape. At this time, it is necessary that the surface in contact with the electronic component be the surface of the ion barrier layer. When the cations such as lithium, potassium, and sodium present in the conductive layer migrate to the surface of the conductive layer by packaging the electronic component in this way, the inorganic ion exchanger in the ion barrier layer transfers the cations. Since these cations are replaced with protons, these cations do not contact and contaminate the electronic component. Also, when anions such as chloride ions and the like, sulfate ions, nitrate ions, perchlorate ions and the like existing in the conductive layer migrate to the surface of the conductive layer, inorganic ions in the ion barrier layer may be removed. Since the hydroxyl group ions are replaced by the ion exchanger, these anions do not come into contact with the electronic component to rust or contaminate the electronic component.

[0017]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following, "parts" and "%" are based on weight unless otherwise specified. 1. To 100 parts of a resin solution comprising 15 parts of a polyurethane resin, 35 parts of toluene and 50 parts of methyl ethyl ketone, 5 parts of alkylammonium ethosulfate was added and stirred to obtain a uniform conductive layer forming solution (solution A). This solution A contains an equivalent amount of an alkyl quaternary ammonium salt as a cation and an alkyl sulfate ester as an anion.

2. Dissolve 10 parts of ferric chloride hexahydrate in a solution of 8 parts of methylcellulose in 2000 parts of water. To this solution, 2.4 parts of pyrrole was added with good stirring to carry out oxidative polymerization of pyrrole to prepare a polypyrrole dispersion (solution B). This solution B contains oxidized iron ions and equivalent amounts of chloride ions. 3. A mixture obtained by adding 10 parts of 1,4-butanediol to 70 parts of polyethylene glycol (molecular weight: 2,000) coordinated with 7 parts of lithium perchlorate is dissolved in a mixed solvent of 50 parts of dimethylformamide and 140 parts of methyl ethyl ketone. . Then, while gradually adding 4,4′-diphenylmethane diisocyanate, the viscosity of
React until 00 poise. After the completion of the reaction, this solution is diluted with methyl ethyl ketone to a solid content of 13%. This diluted solution is referred to as solution C. This solution C contains lithium ions and perchlorate ions in equivalent amounts.

4. 15 parts of a vinyl chloride-acryl copolymer is dissolved in 35 parts of toluene and 50 parts of methyl ethyl ketone to prepare a solution D. 5. To 100 parts of solution D, 3 parts of each of the inorganic ion exchangers shown in Table 1 below were added and dispersed sufficiently. This dispersion is referred to as dispersions D1, D2, and D3.

Example 1 The above solution A was applied to the surface of an amorphous polyethylene terephthalate sheet having a thickness of 0.5 mm by a gravure coating method at a rate of a coating thickness of 1 g / m ² when dried to form a conductive layer. Thus, a conductive sheet (a) was obtained. The surface resistance of this conductive sheet (a) at a temperature of 20 ° C. and a humidity of 70% was 10 ⁸ / □. On the surface of the conductive layer of the conductive sheet (a), the dispersion D was dried to have a film thickness of 0.8 g /
The layer was formed by coating and drying at a ratio of m ² to obtain a conductive sheet (ID) of Comparative Example.

Example 2 In place of Dispersion D, Dispersions D1, D2 and D3 were respectively used, and the others were the same as in Example 1, except that the conductive sheet (a-D1), A-D2) and a conductive sheet (A-D3) were obtained.

Example 3 The above solution B was applied to the surface of a 0.7 mm thick polystyrene sheet at a rate of 0.8 g / m ² when dried to form a conductive layer. Seat (b)
And The temperature of this conductive sheet (b) 20 ° C x humidity 7
The surface resistance at 0% was 10 ⁶ / □. The dispersions D, D1, D2, and D3 were applied to the surface of the conductive layer of the conductive sheet (b) in the same manner as in Examples 1 and ² at a rate such that the film thickness when dried was 0.8 g / m ^2. And dry,
The conductive sheet (b-D) of the comparative example, the conductive sheet (b-D1), the conductive sheet (b-D2), and the conductive sheet (b-D3) of the present invention were obtained.

Example 4 On the surface of a polyvinyl chloride sheet having a thickness of 0.4 mm, the solution C was applied by a gravure method at a rate of a coating thickness of 1 g / m ² when dried, and dried to form a conductive layer. To form a conductive sheet (c). Temperature 2 of this conductive sheet (c)
The surface resistance at 0 ° C. × 70% humidity was 10 ⁶ / □. Example 1, on the surface of the conductive layer of the conductive sheet (c),
The dispersions D, D1, D2 and D3 were applied and dried in the same manner as in Example ^{2 so} that the film thickness when dried was 0.8 g / m ^2. Inventive conductive sheet (C-D1), conductive sheet (C-D2)
And a conductive sheet (C-D3).

Evaluation: A clean 0.1 mm thick copper plate was 3 ×
It was cut into 3 cm to obtain a sample for evaluation. On the other hand, each of the conductive sheets (a), (b), and (c), the conductive sheets obtained in the comparative examples and the examples was 5 × 5 cm.
Cut into pieces. The copper plate is made of two sheets of the conductive sheet,
The ion barrier layer was sandwiched so as to face the copper plate, and the whole was wrapped with a damp cloth, which was sealed in a polyethylene bag so that the moisture of the cloth did not evaporate to the outside. A load of 1 kg was applied from above the bag, and the bag was left at 70 ° C. × 24 hours.
Thereafter, the temperature was returned to room temperature, the copper plate was taken out, and rust generated on the surface of the copper plate was observed. The results are shown in Table 2 below.

[0025]

[0026]

According to the present invention as described above, it is possible to provide a conductive sheet which does not damage electronic components even when an ionic conductive agent is used as a conductive agent or an antistatic agent.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross section of an example of a conductive sheet of the present invention.

FIG. 2 is a diagram schematically showing a cross section of another example of the conductive sheet of the present invention.

[Explanation of symbols]

 1: base material sheet 2: conductive layer 3: ion barrier layer 4: conductive sheet

Claims (3)

[Claims] 1. A conductive sheet having a conductive layer or an antistatic layer provided on at least one surface, wherein an ion barrier layer containing an inorganic ion exchanger is formed on the surface of the conductive layer or the antistatic layer. A conductive sheet characterized by the above-mentioned. 2. An electroconductive sheet, wherein an ion barrier layer containing an inorganic ion exchanger is formed on at least one surface of the electroconductive sheet containing an electroconductive agent and / or an antistatic agent. 3. The conductive sheet according to claim 1, wherein the conductive layer or the antistatic layer contains an ion-conductive conductive agent or an antistatic agent.