JP4569043B2 - Cover tape for packaging electronic parts - Google Patents

Description

【００１３】
比較例４としてＶＡ＝１０％及びＶＡ＝２８％のエチレン−酢酸ビニル共重合体それぞれを混合比率、５０：５０となる様、混合し製膜を試みたが接着剤層の厚みが１５μｍにならない上に均一にならず剥離強度測定には至らなかった。透明性については光線透過率が６５％〜８５％、曇度は２０〜６５％の範囲でばらつき、電子部品の表面に記載された文字を正しく認識するのは困難な結果になった。
表１で得られたカバーテープを５．５ｍｍ巾にスリット後、８ｍｍ巾のポリスチレンを素材とするキャリアテープと１８０℃でシールを行いシール後、５分後に剥離強度を測定した値を表２の初期値に示した。また、それらを室温２３℃湿度５０％(以下、２３℃×５０％RHと略す)、４０℃×９０％、６０℃、−１５℃で３０日保管後、剥離強度を測定した値を表中該当欄に示した。
【００１４】
表２が示す様に比較例１の４０℃×９０％RH、６０℃及び比較例２の６０℃で保管後の測定値は初期値に比べ１０ｃＮ以上剥離強度が減少している事が観察された。また、比較例３では６０℃及び-15℃で保管後の測定値は初期値に比べ３０ｃＮ以上剥離強度が上昇し、また、脈打ち幅も３０ｃＮ以上になっている事が観察された。しかし、これら比較例１〜３で使用した接着剤を混合して得られた実施例１及び２は何れも初期値からの変位及び脈打ち幅共に１０ｃＮ以内に収まっているのが確認された。
【００１５】
【表２】

【００１６】
【発明の効果】
本発明によれば、剥離強度が適度で且つ、透明なカバーテープが得られ、各種の実装トラブルを防止することができる。
【図面の簡単な説明】
【図１】本発明のカバーテープの層構成を示す断面図である。
【図２】実施例で作製したカバーテープの層構成を示す断面図である。
【符号の説明】
１：カバーテープ
２：帯電防止剤層（第１層）
３：二軸延伸フィルム（第２層）
４：接着剤層（第３層）
５：熱硬化性樹脂層
６：ポリエチレン層[0001]
[Technical field to which the invention belongs]
The present invention relates to a plastic carrier in which a storage pocket is formed out of a package that has functions of protecting electronic components from contamination and arranging and taking them out for mounting on an electronic circuit board when storing, transporting and mounting the electronic components. The present invention relates to a cover tape that can be sealed to the tape.
[0002]
[Prior art]
Surface mount electronic components such as ICs, transistors, diodes, capacitors, and piezoelectric element resistors are plastic carrier tapes that are continuously formed with embossed pockets that can be accommodated according to the shape of the electronic components. And a cover tape that can be sealed with a carrier tape. The electronic components of the contents are automatically taken out after the cover tape of the package is peeled off and mounted on the surface of the electronic circuit board. In recent years, electronic components have become smaller and lighter and thinner.
On the other hand, the surface mounting speed has been increased and the speed at which the cover tape is peeled off from the carrier tape has also been increased. For this reason, the pulsation phenomenon that the strength when peeled off (hereinafter referred to as peel strength) becomes stronger or weaker appears remarkably, and so-called jumping troubles that the packaged electronic parts jump out of the carrier tape increase. is doing. In order to prevent such troubles, the number of cases where the peel strength is set to a low value is increasing. For this reason, the cover tape may be peeled off during transportation due to slight changes in peel strength or external force, and the electronic components may spill from the carrier tape. Has also occurred.
When the electronic components to be packaged are relatively large, the peel strength is often set in advance to prevent the carrier tape from popping out during transportation. However, in that case, if the peel strength changes with time and the peel strength becomes too strong, the cover tape may not be smoothly peeled off during mounting, and troubles may occur in which the electronic component cannot be taken out or the cover tape breaks.
[0003]
[Problems to be solved by the invention]
The present invention prevents the above-described jumping troubles during mounting, pop-out of electronic components during transportation due to changes in peel strength over time, and mounting troubles that the cover tape cannot be peeled off smoothly or broken during mounting. A transparent cover tape having a moderate peel strength is provided.
[0004]
[Means for Solving the Problems]
The present invention is a cover tape that can be heat-sealed on a plastic carrier tape in which storage pockets for storing electronic components are continuously formed, and the cover tape is a film made of either polyester or nylon (hereinafter, referred to as a tape). Base material layer) and an adhesive layer made of a thermoplastic resin, and the adhesive layer is made of two or more ethylene-α / olefin copolymers having different weight ratios of ethylene and α / olefin. This is a cover tape for packaging electronic parts.
In the present invention, the α-olefin is vinyl acetate, acrylic acid, methyl acrylate, ethyl acrylate, methacrylic acid, methyl methacrylate, or ionomer, and further has a total light transmittance of 70% or more and a haze of 60. % Is a cover tape for packaging electronic parts.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
An example of components of the cover tape 1 of the present invention will be described with reference to FIG. In the first aspect of the present invention, the surface of the base material layer 3 does not have the antistatic agent layer 2, but it is more preferable to have the antistatic agent layer 2. Antistatic agent layer 2 that is the first layer is a surfactant, polypyrrole-based, polyaniline-based, polythiophene-based π-electron conjugated conductive polymer, or tin oxide, indium oxide, zinc oxide, titanium oxide, carbon black, Consists of conductive fillers such as Si-based organic compounds, polyalkylene glycols and perchlorate complexes such as lithium perchlorate. Uses conductive fillers doped with antimony to improve antistatic properties. May be.
When the antistatic agent layer 2 is not provided, a surfactant such as the above-mentioned antistatic agent or alkylammonium salt is kneaded into the base material layer in advance to impart antistatic properties.
[0006]
The second layer is either a polyester film or a nylon film, but it is preferable to use a stretched film to give rigidity. It is a transparent film with a thickness of 6 to 100 μm.
[0007]
The third layer is made of a thermoplastic resin, is an adhesive layer 4 having a thickness of 0.5 to 100 μm, and is a transparent layer. In order to increase the adhesive strength between the second layer and the third layer, the adhesive surface of the second layer may be subjected to corona treatment, or a thermosetting resin layer 5 such as isocyanate may be provided between the layers. FIG. 1A shows a case where a thermosetting resin layer is not provided between the second layer and the third layer, and FIG. 1B shows a case where a thermosetting resin layer 5 is provided between the second layer and the third layer. Indicates. Further, a polyolefin layer may be provided between the thermosetting resin layer 5 and the adhesive layer 4 in order to provide cushioning properties as a film or to reduce costs.
[0008]
Adhesive layer 4 has ethylene / α / olefin co-polymers in which α / olefin is vinyl acetate, acrylic acid, methyl acrylate, ethyl acrylate, methacrylic acid, methyl methacrylate, and ionomer, and the weight ratio of ethylene and α / olefin is different. It consists of a mixture of two or more coalesces.
In order to impart antistatic properties, the surface of the adhesive layer may be coated or kneaded with an antistatic agent such as a conductive polymer, a conductive filler, or a surfactant.
The lamination method is by extrusion coating, die coater or gravure coater.
[0009]
The cover tape must be laminated so that the total light transmittance is 70% or more and the haze is 60% or less. If the total light transmittance is less than 70% or the haze is 60% or more, it becomes difficult to inspect whether or not the contents are correctly inserted after packaging the electronic component with the cover tape, depending on the inspector.
[0010]
【Example】
Examples of the present invention are shown below, but the present invention is not limited to these examples.
For the adhesive layer 4, vinyl acetate is given as an example of α · olefin. This is because the other α · olefin described above is very similar to vinyl acetate as the adhesive for the cover tape. To represent.
Regarding the base material layer, regarding the peel strength and transparency mentioned as characteristics this time, even if both polyester and nylon are substituted, no significant difference is observed, so polyester is unified.
[0011]
<< About Comparative Examples 1-3, Examples 1 and 2 >>
An antistatic agent layer (first layer) is laminated on one side of a biaxially stretched polyethylene terephthalate film (second layer) having a thickness of 25 μm by a gravure coating method, and then a polyurethane-based thermosetting is applied to the other surface of the second layer. A cover resin having a layer structure as shown in FIG. 2 was obtained by coating an adhesive resin, laminating a 15 μm thick polyethylene on the surface, and laminating an adhesive layer having a thickness of 15 μm on the surface.
The adhesive layer was prepared by previously mixing a mixture of ethylene vinyl acetate copolymers having different weight ratios of ethylene and vinyl acetate shown in Table 1 with a twin-screw continuous extruder.
The total light transmittance and haze were measured according to JIS K7105.
[0012]
[Table 1]

[0013]
As Comparative Example 4, an attempt was made to form a film by mixing ethylene-vinyl acetate copolymers of VA = 10% and VA = 28% so that the mixing ratio was 50:50, but the thickness of the adhesive layer was not 15 μm. It was not uniform on top, and the peel strength was not measured. Regarding the transparency, the light transmittance varied from 65% to 85% and the haze ranged from 20% to 65%, and it was difficult to correctly recognize the characters written on the surface of the electronic component.
After slitting the cover tape obtained in Table 1 to a width of 5.5 mm and sealing with a carrier tape made of 8 mm width polystyrene at 180 ° C. and sealing, the values measured for peel strength after 5 minutes are shown in Table 2. Shown in the initial value. In addition, the values measured for peel strength after storage at room temperature 23 ° C., humidity 50% (hereinafter abbreviated as 23 ° C. × 50% RH), 40 ° C. × 90%, 60 ° C., −15 ° C. for 30 days Shown in the corresponding column.
[0014]
As shown in Table 2, it was observed that the measured values after storage at 40 ° C. × 90% RH, 60 ° C. of Comparative Example 1 and 60 ° C. of Comparative Example 2 decreased by 10 cN or more compared to the initial value. It was. In Comparative Example 3, it was observed that the measured values after storage at 60 ° C. and −15 ° C. increased the peel strength by 30 cN or more compared to the initial value, and the pulse width was 30 cN or more. However, it was confirmed that both Examples 1 and 2 obtained by mixing the adhesives used in Comparative Examples 1 to 3 were within 10 cN in both the displacement from the initial value and the pulse width.
[0015]
[Table 2]

[0016]
【The invention's effect】
According to the present invention, a transparent cover tape having an appropriate peel strength can be obtained, and various mounting troubles can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a layer structure of a cover tape of the present invention.
FIG. 2 is a cross-sectional view showing a layer structure of a cover tape manufactured in an example.
[Explanation of symbols]
1: Cover tape 2: Antistatic agent layer (first layer)
3: Biaxially stretched film (second layer)
4: Adhesive layer (third layer)
5: Thermosetting resin layer 6: Polyethylene layer

Claims (3)

A cover tape that can be heat-sealed to a plastic carrier tape in which storage pockets for storing electronic components are continuously formed. A cover tape for packaging electronic parts, comprising an adhesive layer, wherein the adhesive layer is made of two or more ethylene-α / olefin copolymers having different weight ratios of ethylene and α / olefin. The electronic component packaging cover tape according to claim 1, wherein the α-olefin according to claim 1 is any one of vinyl acetate, acrylic acid, methyl acrylate, ethyl acrylate, methacrylic acid, methyl methacrylate, and ionomer. The cover tape for packaging electronic parts according to claim 1 or 2, wherein the total light transmittance of the cover tape is 70% or more and the haze is 60% or less.

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