JP2901857B2 - Cover tape for packaging chip-type electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package having a function of protecting chip-type electronic components from contamination, and aligning and taking out the chip-type electronic components for mounting on electronic circuit boards when storing, transporting and mounting the chip-type electronic components. The present invention relates to a cover tape which can be heat-sealed to a plastic carrier tape having a storage pocket.

[0002]

2. Description of the Related Art In recent years, transistors such as ICs, transistors, diodes, capacitors, piezoelectric element resistors,
A chip-type electronic component for surface mounting, for example, comprises a plastic carrier tape in which embossed pockets that can be accommodated are continuously formed according to the shape of the electronic component, and a cover tape that can be heat-sealed to the carrier tape. It is supplied in a package. After peeling off the cover tape of the package, the electronic components of the contents are automatically taken out and surface-mounted on the electronic circuit board. The strength at which the cover tape is peeled off from the carrier tape is called peel-off strength. If the strength is too low, the cover tape comes off when the package is transported, and there is a problem that the electronic components as contents fall off. On the other hand, if the cover tape is too strong, the carrier tape vibrates when the cover tape is peeled off, causing a phenomenon of jumping out of the storage pocket immediately before the electronic component is mounted, that is, a jumping trouble. In addition, with the recent significant improvement in surface mounting technology, as high performance and miniaturized electronic components have become more and more chips, the electronic components have been subjected to vibration during transfer of the package, and the carrier tape embossed inner surface, or
Static electricity generated by the friction caused by contact with the inner surface of the cover tape and the spark generated when the cover tape was peeled off from the carrier tape also caused static electricity damage such as destruction / deterioration of electronic components. It has been considered that countermeasures against static electricity on packages such as carrier tapes and cover tapes are the most important issues. Conventionally, the electrostatic treatment of a carrier tape has been performed by kneading or coating carbon black into a material to be used, and a satisfactory effect has been obtained. However, sufficient measures have not yet been taken for the electrostatic treatment of the cover tape, and at present, only the outer layer of the cover tape is coated with an antistatic agent or a conductive material. However, the effect of the treatment is not sufficient for the protection of the enclosed electronic component due to the treatment on the outside of the cover tape, and there is no effect particularly on the static electricity generated by the contact between the inside surface of the cover tape and the electronic component. Also, the electrostatic treatment on the inner surface of the cover tape, that is, the adhesive layer can be performed by coating the antistatic agent or kneading the adhesive layer. In this case, the antistatic agent kneaded into the adhesive layer covers the cover. Bleeding on the inner surface of the tape causes instability of the sealing property, resulting in frequent failure of the sealing, and the electrostatic effect also decreases with time, or the temperature and humidity of the environment in which the package is used. In particular, there is a strong dependence on humidity, and a sufficient effect such as a remarkable decrease in the electrostatic effect has not been obtained under a low humidity of 10% RH. In addition, it is difficult to select a binder that can be stably bonded to the carrier tape for coating, and the peel-off strength is significantly reduced because the original adhesive layer is covered and concealed. In addition, the electrostatic effect has not been performed because the effect is further reduced with time as compared with the time of kneading.

[0003]

SUMMARY OF THE INVENTION The present invention provides a cover tape for packaging a chip-type electronic component in which a countermeasure against static electricity in an adhesive layer is taken, the peel-off strength is dependent on the sealing condition, and the sealing property is stable with little change over time. Is what you do.

[0004]

The present invention has been intensively studied to solve the above-mentioned problems. As a result, a biaxially stretched polyester film is used as an outer layer, and a polyethylene film is used as an intermediate layer between the outer layer and the adhesive layer. A transparent composite film with a high-molecular-weight polyethylene dispersed uniformly in an ethylene vinyl acetate resin as the adhesive layer and a cationic surfactant containing trimethylalkylammonium chloride as the main component is coated on the surface. The present inventors have found that a cover tape having good characteristics can be obtained, and have completed the present invention. That is, the present invention is a cover tape that can be heat-sealed to a plastic carrier tape in which pockets for accommodating chip-type electronic components are continuously formed, and the cover tape has an outer layer of a biaxially stretched polyester film,
The intermediate layer between the outer layer and the adhesive layer is a polyethylene film, and the adhesive layer is a cationic surfactant containing trimethylalkylammonium chloride as a main component, in which high molecular weight polyethylene is uniformly dispersed in an ethylene vinyl acetate resin. A chip type electronic component packaging cover tape characterized by being coated with In a preferred embodiment of the present invention, the amount of the cationic surfactant containing trimethylalkylammonium chloride as a main component is 0.001 to 10 parts by weight with respect to 100 parts by weight of the ethylene vinyl acetate resin in the adhesive layer. The adhesive force between the adhesive layer of the carrier tape and the sealing surface of the carrier tape is a seal width of 1 m.
It is 10 to 120 gr per m, and the visible light transmittance of the cover tape is 75% or more.

[0005]

The constituent elements of the cover tape 1 of the present invention will be described with reference to FIG. 1. The outer layer 2 is a biaxially stretched polyester film and is a transparent and highly rigid film having a thickness of 6 to 100 .mu.m. If it is less than 6μ, the rigidity will be lost, and if it exceeds 100μ, it will be too hard and the seal will be unstable. The mid layer 4 is a polyethylene film. The adhesive layer 5 is made of a transparent ethylene vinyl acetate resin having a molecular weight of 1,000,000 to 600.
In this case, polyethylene having a particle diameter of 0.5 to 200 .mu. Is uniformly dispersed, and has a property capable of being heat-sealed to a plastic carrier tape 6 as a mating material. In addition, the surface of the adhesive layer is uniformly coated with a cationic surfactant containing trimethylalkylammonium chloride as a main component. At this time, the surface resistance of the adhesive layer must be at least 10 ¹³ Ω / □ or less. Preferably, the range is 10 ⁶ Ω / □ to 10 ¹⁰ Ω / □. 10 ¹³
If it is larger than Ω / □, the electrostatic effect becomes extremely poor, and the desired performance cannot be obtained. The addition amount is 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the ethylene vinyl acetate resin of the adhesive layer, depending on the surface resistance characteristics. When the amount is less than 0.001 part by weight, the electrostatic effect is not exhibited, and when the amount is more than 10 parts by weight, the peel-off strength is remarkably reduced, which is not suitable for practical use.
In addition, since the surface resistance of the adhesive layer is adjusted to 10 ¹³ Ω / □ or less, the electronic components come into contact with the cover tape 1 during the transportation in which the electronic components are sealed in the carrier tape 6 with the cover tape 1. Even when the electronic component is picked up by peeling off the cover tape 1, static electricity is not generated, and the electronic component can be protected from an electrostatic failure. In order to further enhance the electrostatic effect, an antistatic treatment layer or a conductive layer may be provided on the outer layer side, that is, on the front and back surfaces of the biaxially stretched polyester film. As for the method of forming the heat-sealable adhesive, the extrusion lamination method is inexpensive and desirable from the viewpoint of hygiene. The thickness of the adhesive layer is 10 to 8
0 μ is preferred, and more preferably 20 to 50 μ.
If the film thickness is 10 μm or less, it is difficult to form a film due to the characteristics of a laminating machine. If the film thickness is 80 μm or more, the winding diameter during long winding becomes large, making it difficult to store the film. In addition, for the purpose of improving the lamination strength of the outer layer and the intermediate layer, both may be laminated via a thermosetting adhesive layer such as an isocyanate type or an imine type. In this case, the adhesive force between the cover tape 1 and the carrier tape 6 is 10 to 10 mm per seal width.
The ethylene vinyl acetate resin for the adhesive layer is selected so as to be 120 gr, more preferably 10 to 70 gr. If the peel-off strength is lower than 10 gr, there is a problem that the cover tape comes off when the package is transferred, and the electronic components as contents fall off. Conversely, if it is higher than 120 gr, the carrier tape will vibrate when the cover tape is peeled off, causing a phenomenon of jumping out of the storage pocket immediately before mounting the electronic component, that is, a jumping trouble. ADVANTAGE OF THE INVENTION According to this invention, the dependence on sealing conditions is low, and the target performance which the peel-off strength and the surface resistance value change with time by storage environment is small can be obtained.

In addition, since high molecular weight polyethylene is dispersed in the adhesive layer, blocking during unwinding of the cover tape is prevented, and at the same time, a void is formed between the adhesive layer and the outer layer during winding, so that trimethylalkylammonium chloride is formed. Is prevented from transferring to the outer layer, and the change in surface resistance over time is suppressed. The alkyl group of the cationic surfactant containing trimethylalkylammonium chloride as a main component preferably has 10 to 20 carbon atoms, and more preferably 12 to 16 carbon atoms. When the concentration is 10 or less, or 20 or more, it is difficult to obtain a surface resistance value at a low concentration. Therefore, when the concentration is adjusted so that the surface resistance value is 10 ¹³ Ω / □ or less, the peel-off strength becomes weak. Become. Since the effective surface resistance value is obtained in a very dilute form with a very low concentration of the agent, the effect of the agent, which is originally said to deteriorate the heat sealability, can be minimized. The particle size of the high molecular weight polyethylene is preferably from 0.5 to 200 µ, more preferably from 10 to 100 µ. When the particle size is 0.5 μm or less, the anti-blocking effect and the effect of suppressing the change with time of the surface resistance value cannot be obtained, and when the particle size is 200 μm or more, the peel-off strength varies greatly. The addition amount is 0.01 to ethylene vinyl acetate resin.
To 50 parts by weight, more preferably 0.01 to 50 parts by weight.
5 parts by weight is good. If the added amount is less than 0.01 part by weight, the anti-blocking effect and the effect of suppressing the time-dependent change of the surface resistance value cannot be obtained, and if it is more than 50 parts by weight, the transparency of the film is remarkably deteriorated. The molecular weight is preferably from 1 to 6 million, and more preferably from 3 to 5.5 million. If the molecular weight is 1,000,000 or less, it will be melted during extrusion lamination, and the anti-blocking effect and the effect of suppressing the change of the surface resistance over time will not be obtained. If the molecular weight is 6,000,000 or more, polyethylene will not be easily melted during purging of a laminating machine. In addition, the man-hour for replacing the resin is reduced. In addition, since the visible light transmittance of the cover tape is 75% or more, preferably 80% or more, the internal electronic components enclosed in the carrier tape can be visually or mechanically confirmed. If it is lower than 10%, it is difficult to confirm the electronic components inside.

[0007]

EXAMPLES Examples of the present invention are shown below, but the present invention is not limited by these examples. << Examples 1, 2, 3, 4, 5 >><< Comparative Examples 1, 2, 3, 3 >>
4,5 >> Biaxially oriented polyester film having a thickness of 25 μm and a thickness of 15
An adhesive layer made of an ethylene vinyl acetate resin and 1 part by weight of polyethylene having a molecular weight of 5,000,000 and a particle diameter of 100μ uniformly dispersed in an ethylene vinyl acetate resin to a thickness of 15μ on the polyethylene film side of a laminated product of a polyethylene film of μμ. The cationic surfactant containing trimethyldodecylammonium chloride as the main component (Kao Co., Ltd.)
1) coated with a surfactant (a surfactant). Apply the obtained cover tape to 13.4
After slitting to a mm width, heat sealing was performed with a PS carrier tape having a width of 16 mm, and the peel-off strength was measured. or,
The surface resistance of the adhesive layer was measured in accordance with JIS-K-6911, and the characteristics evaluation results are shown in Table 1. * The adhesive layer in the comparative example is a resin instead of the ethylene vinyl acetate resin. * The number of surfactant is the amount added to 100 parts by weight of ethylene vinyl acetate resin in the adhesive layer. * Heat sealing conditions: 140-180 ° C / 20psi / 1s
ec. Seal width 0.4mm × 2 * Peel condition: 180 ° peel, peel speed
300mm / min.n = 3

[0008]

[Table 1]

[0009]

[Table 2]

[0010]

According to the present invention, the adhesive layer is electrostatically treated, so that the static electricity generated when the electronic component comes into contact with the cover tape or the cover tape is peeled off is suppressed, and the electrostatic effect is used. It is stable to the environment and changes over time and does not affect the sealing performance.
Point that can be set arbitrarily in the range of 10 to 120 gr per mm,
Due to these two problems, there are the conventional problems of the contact between the electronic component and the cover tape or the problem of static electricity generated when the cover tape is peeled off, the problem that the peel-off strength greatly depends on the sealing conditions, and the aging due to the storage environment. In this way, the problem which changes gradually can be solved, and a stable peel-off strength can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a layer structure of a cover tape of the present invention.

FIG. 2 is a cross-sectional view showing a state in which the cover tape of the present invention is adhered to a carrier tape and used.

Claims (7)

(57) [Claims] 1. A cover tape that can be heat-sealed on a plastic carrier tape in which storage pockets for accommodating chip-type electronic components are continuously formed, wherein the cover tape has a biaxially stretched polyester film as an outer layer. ,
The intermediate layer is a polyethylene film, and the adhesive layer is formed by uniformly dispersing a high-molecular-weight polyethylene in an ethylene vinyl acetate resin, and a cationic surfactant containing trimethylalkylammonium chloride as a main component is further provided on the adhesive layer surface. A chip-type electronic component packaging cover tape characterized by being coated. 2. The high-molecular-weight polyethylene has a particle size of 0.5 to 0.5.
2. The cover tape for packaging chip-type electronic components according to claim 1, which has a thickness of 200 μm. 3. The cover tape for packaging chip-type electronic parts according to claim 1, wherein the amount of the high-molecular-weight polyethylene is 0.01 to 50 parts by weight based on 100 parts by weight of the ethylene vinyl acetate resin in the adhesive layer. . 4. The high molecular weight polyethylene having a molecular weight of 100
The cover tape for packaging a chip-type electronic component according to claim 1, wherein the number is in the range of 10,000 to 6,000,000. 5. The method according to claim 1, wherein the alkyl group of the trimethylalkylammonium chloride has 10 to 20 carbon atoms.
5. The cover tape for packaging a chip-type electronic component according to 3 or 4. 6. The amount of the cationic surfactant containing trimethylalkylammonium chloride as a main component is 0.001 to 10 parts by weight based on 100 parts by weight of the ethylene vinyl acetate resin of the adhesive layer, and the surface of the adhesive layer is The resistance value
The cover tape for packaging chip-type electronic components according to claim 1, 2, 3, 4, or 5, which has a resistivity of 10 ¹³ Ω / □ or less. 7. The visible light transmittance of the cover tape is 75%.
7. The cover tape for packaging a chip-type electronic component according to claim 1, 2, 3, 4, 5, or 6.