JPH0387099A - Lid of conductive carrying body for electronic parts - Google Patents

Abstract

PURPOSE:To obtain superior conductivity and improve adhesion with a bottom member, by laminating ethylene-vinyl acetate copolymer based resin composition containing antistatic agent of a specified range ratio, on the side in contact with electronic parts. CONSTITUTION:A conductive carrying body is constituted of a tape-type base member 1 and a tape-type lid 2 heat-sealed with the base member. The lid 2 is bonded to the upper surface of the bottom member 1, so as to completely cover a recessed part 11. The lid 2 is constituted of a base sheet 21 and a seal layer 22, and in case of need, an anchor coat layer 23 is arranged between the sheet and the seal layer. The layer 22 has a two-layer structure of a polyethylene layer 22a and ethylene-vinyl acetate copolymer 22b containing 0.2-0.5wt.% antistatic agent. Hence the lid 2 has sufficient conductivity as a lid, and further has the adhesion with the bottom member 1 and mechanical strength.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a lid for a conductive carrier for electronic components used for taping packaging of electronic components, and particularly has sufficient conductivity and has a bottom material that is heat-resistant. The present invention relates to a lid for a conductive carrier for electronic components that has good adhesion when sealed.

[Prior art and problems to be solved by the invention] In recent years, electronic components have been automatically attached to circuit boards for the purpose of automating the production of electronic devices. To make it easier, each electronic component is wrapped in a tape-like carrier called a carrier tape, and the carrier tape is sent out one after another to automatically pick up the electronic components and automatically place them at a predetermined location on the circuit board. I am wearing it.

The conveyor used for automatic mounting of electronic components is
Both generally consist of a tape-shaped bottom material and a lid (cover tape), and the bottom material has recesses for housing electronic components formed at regular intervals, and one or both sides of the recesses are formed at a constant pitch. The lid has a width that completely covers the recess containing the electronic component, and is bonded to the bottom material on both sides by heat sealing or the like.

Polystyrene, polyvinyl chloride, polyethylene, etc. are usually used as the bottom material of such carriers for electronic components due to their strength and cost, and ethylene-acetic acid is used as the lid material due to its adhesive properties. Vinyl copolymer (EVA) is used.

By the way, as electronic components become smaller and more precise, it is becoming increasingly important to prevent dielectric breakdown caused by high voltage. For this purpose, it is necessary to make the carrier conductive to prevent charge from accumulating.

For the purpose of imparting such conductivity, a large amount of fine particles of conductive substances such as carbon are blended into polyvinyl chloride resin as the bottom material of the carrier, and the surface resistance is reduced to 10@0.
Some use resin sheets with 7 holes or less.

Also, as a sheet for packaging electronic parts, JP-A-57-205
No. 145 contains 5 to 5 carbon black on one or both sides of a polystyrene or ABS resin sheet base material.
A composite plastic sheet is disclosed in which films or sheets of polystyrene or ABS resin containing 50% by weight and a surface resistance value of 1010Ω or less are integrally laminated by coextrusion. There is also a bottom material that uses a multilayer sheet made by laminating sheets.

On the other hand, it is desirable that the lid heat-sealed to the conductive bottom material as described above also has some degree of conductivity.

However, lids coated with a conductive paint or antistatic agent, or kneaded with a conductive material such as carbon black, have a problem of poor heat-sealability to the bottom material. In addition, since the total thickness of the lid is extremely thin compared to the bottom material, if a conductive material is mixed in, the content will be large! There was also the problem that the strength was likely to decrease.

In this way, (a) there is little variation in peel strength when heat-sealed to the bottom material, (b) it has antistatic properties, and (C
) - There has been no conventional lid that satisfies all of the requirements for a conductive lid, such as having mechanical strength greater than that of a window.

Therefore, an object of the present invention is to provide a lid for a conductive carrier for electronic components, which has electrical conductivity, good adhesion to the bottom material, and high mechanical strength.

[Means to solve the problem]

As a result of intensive research in view of the above purpose, the present inventor has found that even if the entire lid of the carrier is not made conductive, if the side that contacts the electronic components is made conductive, it is sufficient to protect the electronic components. The inventors have discovered that by incorporating a specific amount of an antistatic agent into BVA, it is possible to prevent a decrease in heat sealability and mechanical strength, and have come up with the present invention.

That is, the lid of the conductive carrier for electronic components of the present invention is made up of a sealing material layer and a base sheet in order from the adhesive side to the bottom material, and the sealing material layer is coated with antistatic agent 0 in order from the adhesive side.
．． It is characterized by consisting of an ethylene-vinyl acetate copolymer (BVA) layer containing 2 to 0.5% by weight and a polyethylene layer.

The present invention will be explained in detail below.

FIG. 1 is a plan view of a conductive carrier according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view taken along line AA in FIG.

The conductive carrier consists of a tape-like bottom material 1 and a tape-like lid 2 heat-sealed thereto.
) and feeding holes 12 provided at a constant pitch (b) on one side. Further, the lid 2 is bonded to the upper surface of the bottom material 1 by heat sealing or the like so as to completely cover the recess 11. In such a conductive carrier, electronic components 6 are loaded as shown by the dashed line in FIGS. 1 and 2.

In FIG. 2, the bottom material 1 has a three-layer structure of a conductive polystyrene layer 3/a polystyrene layer 4/a conductive polystyrene layer 5, as described later.

FIG. 3 shows the structure of a lid that is heat-sealed to the bottom material of such a conductive carrier. In the embodiment shown in FIG.
The conductive lid 2 includes a base sheet 21 and a sealing material layer 22.
An anchor coat layer 23 is provided between both layers as necessary. The sealing material layer 22 includes a polyethylene layer 22a and an ethylene layer containing an antistatic agent.
It has a two-layer structure including a vinyl acetate copolymer ([EVA) layer 22b.

From the viewpoint of mechanical strength, it is preferable to use polyester such as polyethylene terephthalate for the base sheet 21. Particularly in the present invention, it is preferable to use a sheet of polyethylene terephthalate that has been subjected to antistatic treatment with a nonionic surfactant or the like in order to obtain good layer conductivity.

For the polyethylene layer 22a constituting the sealing material layer 22, polyethylene to which a colorant, stabilizer, plasticizer, etc. are appropriately added can also be used.

Further, in the present invention, [EVA layer 22b is ethylene-
Adding antistatic agent to vinyl acetate copolymer (EVA) from 0.2 to
It consists of a BVA-based resin composition containing 0.5% by weight.

In the present invention, ethylene-vinyl acetate copolymer (IEV
A) is not particularly limited, but EVA preferably has a vinyl acetate content of 5 to 20% by weight. Generally, if the vinyl acetate content is too low, the heat seal strength with the bottom material and the shelf life will be significantly reduced.

Moreover, it is meaningless even if the content of vinyl acetate is too high.

As the antistatic agent, from the viewpoint of preventing deterioration of adhesion with the bottom material and moldability, surfactant-based antistatic agents, surfactant-based antistatic agents, fatty acid amides, aliphatic amines, It is preferable to use a mixture of an organic antistatic agent such as a urea derivative, and in particular a mixture of a nonionic surfactant or a combination of a nonionic surfactant + glycerin and a carboxylic acid (such as stearic acid). Preference is given to using monoesters.

The content of the antistatic agent is as follows: Composition 1 of the BVA layer 22b
The ratio is 0.2 to 0.5% by weight relative to 0.00% by weight. If the amount added is less than 0.2% by weight, the surface resistance value of the lid cannot be sufficiently lowered, and if it exceeds 0.5% by weight, the heat sealability with the bottom material will be significantly reduced. Due to the addition of anti-static agent, the surface resistance of the sealing surface of this lid is 10”
It is less than Ω/lo order, preferably less than 10907 units. Since the surface resistance of EVA without the addition of an antistatic agent is 1016 Ω/ro or more, it can be seen that the conductivity is significantly improved.

Furthermore, when the anchor coat layer 23 is provided between the base sheet 21 and the sealing material layer 22, a general-purpose anchor coat agent such as polyethyleneimine, urethane, isocyanate, etc. can be used as the anchor coat agent.

The total thickness of the lid consisting of each layer as described above is 47 to 145.
μm1 is preferably 55 to 85 μm. If the thickness of the lid material is thinner than 47 μm, the strength will be impaired, and 14
If it is thicker than 5 μm, heat transfer during heat sealing will be poor.

The thickness of each layer is 12 to 50 μm for the base sheet 21.
1. The sealing material layer 22 has a thickness of 35 to 95 μm, the polyethylene layer 22a in the sealing material layer has a thickness of 15 to 50 μm, and EVA
The layer 22b has a thickness of 15 to 50 μm. Preferably, the paste sheet 21 has a thickness of 15 to 25 μm and the sealing material layer 22 has a thickness of 4 μm.
0 to 60 μm, and the polyethylene layer 2 in the sealing material layer
2a is 20-30 μm 5IEVA layer 22b is 2
It is 0 to 30 μm.

The thickness of the base sheet 21 is determined for the purpose of reinforcement, and if it is not within the above range, the strength will be impaired. Furthermore, if the sealing material layer 22 is less than 35 μm, the peel strength will vary widely, making it difficult to open the conductive carrier gently, and if it exceeds 95 μm, there is no point. Furthermore, if the BVA layer 22b in the sealing material layer 22 is less than 15 μm,
It becomes difficult to obtain sufficient conductivity and adhesion, and the
Even if it exceeds m, a commensurate improvement in the effect cannot be obtained,
It is not economical because the amount of the BVA resin bottom composition used increases.

A conductive lid having such a multilayer structure can be obtained by the following method.

First, the above-mentioned EVA and antistatic agent were mixed at 140 to 22
The mixture is kneaded at 0°C, then extruded through a gouer, and molded by a T-die method or the like to form a BV^ film.

Next, using this EV^ film, a laminated sheet that will become a lid is manufactured using an apparatus as shown in FIG. This device includes each roll 42A for guiding the base sheet 41.
~42F and Zara 4, a paint containing anchor coating agent
3, anchor roll 44, 44', and drying device 4
5, a polyethylene extruder 46, a die 47, and a BV
A. It has a roll 49 for guiding the sheet 48, a pressure roll 50, 50', and a roll 51 for guiding the laminated sheet to a take-up roll (not shown).

In such an apparatus, an anchor coating agent is applied to the base sheet 41 and dried in a drying device 45 to improve the anchor coating layer, and then polyethylene is extruded between the base sheet 41 and the BVA sheet 48 and laminated. A laminated sheet can be obtained by this. Furthermore, if an anchor coat layer is not required, similar extrusion lamination may be performed without performing the steps of applying and drying the anchor coat agent.

The bottom material to which this conductive lid is heat-sealed is not particularly limited, but from the viewpoint of adhesion, it is preferable that the layer to be heat-sealed contains 5 to 20% by weight of BVA.

An example of such a bottom material is shown in FIG. The bottom material 1 has a conductive polystyrene layer 3 and a polystyrene layer 4, and further has a conductive polystyrene layer 5 below the polystyrene layer 4, if necessary.

The conductive polystyrene layer contains 65 to 75% by weight of polystyrene and 5 to 5% of ethylene-vinyl acetate copolymer (E!VA).
It is made of a conductive polystyrene resin composition containing 15% by weight and 10 to 25% by weight of carbon.

There are no particular restrictions on the molecular weight of polystyrene, and its blending ratio is 65 to 75% by weight.

If the blending ratio of polystyrene is less than 65% by weight, E! V.A.
If the amount exceeds 75% by weight, the blending amount of EVA and carbon becomes too low.

The blending ratio of ethylene-vinyl acetate copolymer (BVA) is generally 5 to 15% by weight, and preferably in the range of 5 to IO weight%. BVA blending ratio is 5% by weight
If it is less than 1, the adhesive strength with the lid will decrease over time, and if it is less than 1
If it exceeds 5% by weight, blending with polystyrene becomes difficult.

In addition, the content of vinyl acetate (VA) in BVA is
Depending on the amount of A used, generally 0.8 for the total composition
It is preferable that the amount is at least % by weight.

The blending ratio of carbon in the conductive polystyrene resin composition is 10 to 25% by weight, particularly preferably 10 to 20% by weight. If the blending ratio of carbon is less than 10% by weight, the conductivity of the conductive polystyrene resin composition will not be sufficient, and if it exceeds 25% by weight, if the bottom material is stored at high temperatures for a long period of time, carbon will cause the surface of the bottom material to deteriorate. This bleeds out, reducing the shelf life of the heat seal with the lid. The surface resistance of the conductive polystyrene layer containing an appropriate amount of carbon is 10@07 or less, preferably 10'0.
7 mouths or less.

In particular, in the conductive polystyrene resin composition as described above, in order to improve the compatibility between polystyrene and ethylene-vinyl acetate copolymer (13VA), styrene-
It is preferable to add the butadiene rubber in an amount of 7 to 10% by weight based on the total composition.

In addition to the above-mentioned components, appropriate amounts of heat stabilizers, antioxidants, light stabilizers, flame retardants, plasticizers, antistatic agents, etc. may be added as necessary.

The polystyrene layer 4 is not limited to a polystyrene homopolymer, but may also be a blend of other components such as rubber.

Note that in order to protect the electronic components, it is sufficient if the conductive polystyrene layer 3 is provided on the electronic component side.
In order to obtain good layer conductivity, as shown in Figure 2,
Preferably, a conductive polystyrene layer 5 is also provided on the outside.

The total thickness of the bottom material made up of each layer as described above can be changed as appropriate depending on the size and weight of the electronic components to be loaded.
Generally it is 0.2-2.0 mm.

Further, the thickness of the conductive polystyrene layer 3 is preferably 30 to 85 μm in order to obtain sufficient conductivity. In addition, when the conductive polystyrene layer 5 is also provided on the lower side, the thickness of the conductive polystyrene layer 5 may be the same as the thickness of the conductive polystyrene layer 3; For example, the material is made by extruding two or three layers of each required resin from a gooey having a multi-manifold, then stretching this to form a laminated sheet, forming recesses 11 in the obtained laminated sheet, and It can be obtained by drilling a feed hole 12 in the part.

Such a bottom material weighs 10 to 70 g for the lid of the present invention.
Peel strength within f (strength when heat-sealed with a width of 1 + + + n and peeled at a speed of 300 mm and 7 minutes)
has. Further, the peel strength has little variation throughout, and the difference between the maximum and minimum is only within 30 gf.

[For production]

The lid of the conductive carrier of the present invention has a side that comes into contact with electronic components.
Since the bottom is laminated with an εV^-based resin containing an antistatic agent, it has a sufficiently small surface resistance value as a lid.

Further, although the EVA layer contains an antistatic agent, the content is within a specific range, so that heat sealability does not deteriorate.

In particular, the antistatic agent-containing EVA-based resin composition forming the back layer exhibits good heat-sealing properties for lids containing EVA and has extremely small variations in sealing strength.

〔Example〕

The present invention will be explained in further detail by the following specific examples.

Example 1, Comparative Example 1 Creating a lid A 30 μm BVA resin sheet and a 25 μm polyethylene terephthalate sheet treated with antistatic treatment using a nonionic surfactant were extruded and laminated with 15 μm polyethylene to form a lid. A laminated sheet was obtained.

In addition, the EvA resin is used as an antistatic agent in a total of 10
0% by weight, 0.5% by weight of a nonionic surfactant (Stayside, manufactured by Tokyo Denki Kagaku Kogyo ■) was added.In addition, the polyethylene terephthalate sheet was added with incyanate as an anchor coating agent on the laminate surface. It is coated to form an anchor coat layer.

For each test, the bottom material for heat-sealing the lid of the present invention had a three-layer structure of conductive polystyrene layer/polystyrene layer/conductive polystyrene layer, with a total thickness of 0.4 a + m and a ratio of the thickness of each layer. A sheet with a ratio of 1:5:1 was prepared by coextrusion, and this sheet was provided with recesses and feed holes to be used as a bottom material. In addition, the conductive polystyrene resin composition forming the conductive polystyrene layer has a content of 15% based on the entire resin composition.
% by weight of carbon. Moreover, the surface resistance value of this bottom material was 2 XIO' Ω/mouth.

The above-mentioned lid was heat-sealed to this bottom material with a width of 1 mm at 170 °C for 1 second, and the peel strength was measured immediately after heat-sealing and after storage at a temperature of 60 °C and humidity of 90% for 5 days, IO days, and 30 days. and surface resistance values were measured. Also,
For comparison, a lid containing no antistatic agent (Comparative Example 1) was prepared, and its peel strength and surface resistance were measured in the same manner.

The conditions for measuring peel strength were as follows.

Peeling angle: 180 to the tape surface.

Peeling speed: 300mm/min In addition, Surface resistance value is made by Mitsubishi Yuka. lorester Measured using.

The results are shown in Table 1.

Table 1 shows that the lid of the conductive carrier of the present invention maintains a surface resistance value of 10 even when stored for 30 days under strict storage conditions.
It can be seen that the peel strength can be on the order of Ω/mm, and that there is little variation in peel strength.

〔Effect of the invention〕

As detailed above, the lid of the conductive carrier of the present invention has an antistatic agent-containing EVA layer on the side that is bonded to the bottom material, so it has sufficient conductivity as a lid. Moreover, it has good adhesion to the bottom material and good mechanical strength. Especially EVA
The bottom material containing not only good heat sealability but also very small variation in peel strength (difference between maximum and minimum). Therefore, the lid of the electronic component carrier can be stably peeled off with a constant force, making automatic handling of electronic components reliable and easy. Furthermore, since the heat seal strength has good storage stability, there is almost no variation in peel strength depending on the length of the storage period.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a conductive carrier, FIG. 2 is an enlarged sectional view taken along the line A-A in FIG. 1, and FIG. 3 is a layered structure of the lid of the conductive carrier of the present invention. FIG. 4 is a schematic diagram showing the manufacturing process of the lid of the conductive carrier of the present invention. 1... Bottom material 11... Recessed part 12 for attaching components - Sprocket hole 2 - Lid 3.5 - Conductive polystyrene layer 4... Polystyrene layer 6... Electronic components 21 - Base sheet 22・・Seal material layer 22 & ・・Polyethylene layer 22b ・・Ethylene-vinyl acetate copolymer layer 23
... Anchor coat layer 41... Base sheet 42A-F, 49.51... Roll 43...
Paint roll 44.44'... Anchor roll 45... Drying device 46... Extruder 47... Gui 48... EVA sheet 50.50'... Pressing roll

Claims (5)

[Claims] (1) The bottom material of a tape-shaped conductive carrier for electronic components, which has concave portions for loading electronic components at regular intervals and has sprocket holes provided at a constant pitch on one or both of its sides. A tape-shaped lid that is adhered to the bottom material so as to completely cover the recess is made up of a sealing material layer and a base sheet in order from the adhesive surface side to the bottom material, and the sealing material layer is bonded to the bottom material from the adhesive surface side. Antistatic agent 0.2-0.5% by weight in order
1. A lid for a conductive carrier for electronic components, comprising an ethylene-vinyl acetate copolymer layer containing polyethylene and a polyethylene layer. (2) In the lid of a conductive carrier for electronic components according to claim 1, the antistatic agent is a nonionic surfactant, or a nonionic surfactant and a monoester of glycerin and carboxylic acid. A lid for a conductive carrier for electronic components, characterized by: (3) In the lid of the conductive carrier for electronic components according to claim 1 or 2, the total thickness of the lid is 47 to 145 μm, the base sheet has a thickness of 12 to 50 μm, and the sealing material layer has a thickness of 35 μm. 95 μm, the ethylene-vinyl acetate copolymer layer in the sealing material layer has a thickness of 15 to 50 μm, and the polyethylene layer has a thickness of 15 to 50 μm. (4) A lid for a conductive carrier for electronic components according to any one of claims 1 to 3, wherein the base sheet is made of a polyethylene terephthalate sheet subjected to antistatic treatment. Lid for conductive carrier. (5) The lid of the conductive carrier for electronic components according to any one of claims 1 to 4, further comprising an anchor coat layer between the base sheet and the sealing material layer. Lid for conductive carrier.