Conductive reel and method for manufacturing the same

Abstract

To provide a conductive reel with high impact strength while maintaining conductivity. [Solution] The conductive reel around which a carrier tape for housing electronic components is wound is a resin molded product formed by sandwich molding into a three-layer structure consisting of a core layer and skin layers on both sides thereof, wherein the core layer is made of a non-conductive resin that does not have conductivity, and the skin layers are made of a conductive resin that has conductivity.

Description

Technical Field

[0001] The present invention relates to a conductive reel for winding a carrier tape for packaging electronic components and the like, and a method for manufacturing the same.

Background Art

[0002] In recent years, the demand for high-performance and small-sized electronic components, particularly chip-type electronic components such as ICs, transistors, and diodes, has been increasing. These chip-type electronic components are stored in a carrier tape or tray obtained by secondarily molding a plastic sheet by vacuum molding, pressure-air molding, press molding, or the like, and are transported and stored.

[0003] The carrier tape has a pocket portion for storing an electronic component. After the electronic component is stored in the pocket portion and sealed with a cover tape as a lid material, it is wound around a reel and transported to a user as a package. The reel for the carrier tape is composed of a pair of opposing disk-shaped side plates and a circular winding core portion (hub portion) disposed at the center between these side plates. The carrier tape containing the electronic component is wound around the hub portion. Thus, the reel for the carrier tape winds up the carrier tape used for, for example, mounting, transporting, and storing electronic components and semiconductors, and is used for their transportation, management, feeding operation, and the like (Patent Document 1).

[0004] In order to suppress charging of electronic components and prevent electrostatic breakdown, conductivity is imparted to the reel for the carrier tape. As a reel for the carrier tape (conductive reel) imparted with conductivity for such a purpose, for example, a resin composition obtained by adding a conductive material (carbon powder) to polystyrene and kneading it is molded into a predetermined shape by injection molding or the like (Patent Documents 2 and 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, conductive reels made by molding a single composition containing carbon powder, a conductive material, contain a relatively large amount of carbon to ensure conductivity. Compared to reels made entirely of non-conductive resin, they have the disadvantage of being weak to impact, such as cracking if dropped during handling.

[0007] Therefore, the object of the present invention is to provide a conductive reel with high impact strength while maintaining conductivity, and a method for manufacturing the same. [Means for solving the problem]

[0008] The conductive reel configuration in the present invention is a resin molded product formed by sandwich molding into a three-layer structure consisting of a core layer and skin layers on both sides of the core layer, on which a carrier tape for housing electronic components is wound, characterized in that the core layer is made of a non-conductive resin that does not have conductivity, and the skin layers are made of a conductive resin that has conductivity. In the above configuration, preferably the conductive reel has two disc-shaped side plates, each of the side plates has a protruding portion that protrudes from its center in the direction of the rotation axis, and by joining the protruding portions facing each other, the conductive reel is formed in which the side plates are arranged facing each other with at least the width of the carrier tape separating them, and the tip portions of the protruding portions are molded so that the core layer is exposed. For example, the non-conductive resin is a recycled material produced by a recycling process. Alternatively, for example, the conductive resin is a mixed material in which a non-conductive resin and a recycled material produced by a recycling process are mixed to the extent that it has the necessary conductivity.

[0009] The present invention relates to a method for manufacturing a conductive reel on which a carrier tape for housing electronic components is wound, wherein the conductive reel has two disc-shaped side plates, each of the side plates has a protruding portion that protrudes from its center in the direction of the rotation axis, and the side plates are joined together with the protruding portions facing each other so that they are arranged facing each other with at least the width of the carrier tape separating them, wherein the side plates are formed into a three-layer structure consisting of a non-conductive core layer and conductive skin layers on both sides by sandwich molding, and furthermore, in the sandwich molding process, the tip portions of the protruding portions of the side plates are injection molded so that the core layer is exposed. [Effects of the Invention]

[0010] According to the present invention, a conductive reel is provided having a three-layer structure consisting of a conductive surface skin layer and a non-conductive internal core layer. By using a three-layer structure, it is possible to achieve a structure with high impact strength while maintaining conductivity. Furthermore, by injection molding so that the core layer is exposed from the tip of the protruding portion that protrudes from the side plate of the conductive reel, the welding strength between the side plates is increased, and the impact performance is improved. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows an example of the external configuration of a conductive reel in an embodiment of the present invention. [Figure 2] This diagram illustrates the three-layer structure of the side plate 10 of the conductive reel 1 in this embodiment. [Figure 3] This figure shows the relationship between carbon black content and surface resistivity. [Figure 4] This diagram illustrates the sandwich molding process for forming a conductive reel with a three-layer structure. [Figure 5] This diagram schematically shows the state in which the material is filled into the mold of conductive reel 1 by sandwich molding. [Figure 6]This is a diagram for explaining the structure of an injection molding machine for sandwich molding. [Figure 7] In the molding of the protruding portion 11 of the side plate 10, it is a schematic cross-sectional view showing a state where the core material is partially exposed from the skin material. [Figure 8] It is a photograph of a prototype conductive reel, showing a state where the core layer 30 is exposed from the skin layer. [Figure 9] This is experimental data showing the conductive characteristics of the conductive skin layer in the conductive reel 1 of the present invention.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, such embodiment examples do not limit the technical scope of the present invention.

[0013] FIG. 1 is a diagram showing an example of the external configuration of a conductive reel in an embodiment of the present invention. FIG. 1(a) is an overall perspective view of the conductive reel, FIG. 1(b) is a front view of the conductive reel, and FIG. 1(c) is a perspective view of only one side plate of the conductive reel.

[0014] The conductive reel 1 includes two side plates 10 formed in a disc shape, and the two side plates 10 are arranged to face each other with at least the width of a carrier tape (not shown) therebetween. At the center of each of the two side plates 10, an insertion hole 90 for inserting a rotating shaft (not shown) for rotatably supporting the conductive reel 1 is formed through, and around the insertion hole 90, a protruding portion (convex portion) 11 protruding in the direction of the rotating shaft from the surface of the side plate 10 is formed. The protruding portion 11 forms one side of the core portion (hub portion) of the conductive reel. The side plate 10 including the protruding portion 11 is generally made by injection molding, and by joining the protruding portions 11 of the two side plates 10 to face each other, the conductive reel 1 with a core portion (hub portion) formed is obtained. The disc portion of the side plate 10 may also be referred to as a flange portion, and the protruding portion 11 may be referred to as a core portion.

[0015] The tip portions 91 where the opposing protruding portions 11 contact each other are welded. The tip portions 91 are heat-welded by a known heat welding device, whereby the two side plates 10 are joined to form the conductive reel 1.

[0016] The side plate 10 of the conductive reel 1 in the present embodiment is a resin molded product formed into a three-layer structure composed of an inner core layer and skin layers on both sides thereof by sandwich molding. The skin layer is composed of a conductive resin material having conductivity, and the core layer is composed of a non-conductive resin material having no conductivity.

[0017] FIG. 2 is a diagram for explaining the three-layer structure of the side plate 10 of the conductive reel 1 in the present embodiment, and schematically shows a cross section of the side plate 10 of the conductive reel 1. The dimensions of the side plate 10 shown in FIG. 2 are examples. The side plate 10 has a three-layer structure composed of a conductive skin layer 20 formed on one surface side, a non-conductive core layer 30 located inside, and a conductive skin layer 20 on the opposite surface. The skin layer 20 is formed of a conductive resin material (skin material) containing a conductive filler such as carbon black or carbon nanotubes to impart conductivity, and the core layer 30 is composed of a general-purpose resin material (for example, polystyrene, polypropylene, etc.) that does not contain a conductive filler. The resin material (core material) forming the core layer 30 may be a recycled material (reclaimed material) produced by a predetermined recycling process (regeneration process). By using a recycled material (reclaimed material) as the core material, it is possible to reduce the material cost while suppressing variations in product quality. And the conductive reel having this three-layer structure can be manufactured by adopting a sandwich molding process.

[0018] Also, preferably, it is also possible to use a recycled material for the skin material. For example, a commercially available conductive resin material currently in circulation is composed of about 40% carbon black as a conductive filler and 60% polystyrene as a general-purpose resin material (virgin material). A mixture of a recycled material of a general-purpose resin material and this commercially available conductive resin material can be used as the skin material.

[0019] Figure 3 shows the relationship between carbon black content and surface resistivity. The conductive properties of the skin layer formed by the skin material are as follows: surface resistivity 10 4 -10 9 The required conductivity is within the range of Ω / □. As shown in the graph in Figure 3, even with a carbon black content of about 20%, the required conductivity is a surface resistivity of 10 4 -10 9 Since the Ω / □ range can be maintained, a conductive resin material (mixed material) can be used as a skin material by mixing the above-mentioned commercially available conductive resin material with recycled general-purpose resin material that does not have conductivity in a mixing ratio of approximately 1:1, for example, and adding about 20% carbon black. The mixing ratio of the recycled material (recycled material) is adjusted to obtain the conductivity required for the skin layer. By using recycled material (recycled material) for the skin material, material costs can be reduced, and the use of recycled material contributes to environmental protection.

[0020] Figure 4 illustrates the sandwich molding process for forming a conductive reel with a three-layer structure. First, in an injection molding machine, as shown in Figure 4(a), the skin material (conductive resin) in the main cylinder is injected from a nozzle connected to the main cylinder, with the outer circumference of the inner nozzle serving as a flow path, to form a skin layer 20 on the inner wall surface of the mold. Next, as shown in Figure 4(b), the core material (non-conductive resin) in the sub-cylinder is injected from the inner nozzle, thereby filling the inside of the skin layer 20 with a core layer 30. Furthermore, as shown in Figure 4(c), the skin material (conductive resin) is injected again to seal the gate portion, forming a three-layer structure of skin layer 20 / core layer 30 / skin layer 20.

[0021] Figure 5 schematically shows the state in which the mold for the conductive reel 1 is filled with material by sandwich molding. As an example, conductive resin, which is the material for the skin layer 20 (skin material), is filled from the main cylinder of the injection molding machine, and non-conductive resin, which is the material for the core layer 30 (core material), is filled from the sub-cylinder. The core layer 30 is located in the central part, and the skin layer 20 is formed on both surfaces of it, creating a structure that combines conductivity and mechanical strength. The tip of the outer peripheral portion of the side plate 10 has a structure in which the core layer 30 is covered with the skin layer 20, but as will be described later, the tip of the protruding portion 11 has a structure in which the core layer 30 is intentionally exposed by causing a so-called breakthrough phenomenon.

[0022] Figure 6 illustrates the structure of an injection molding machine for sandwich molding. In order to inject a conductive resin, which has relatively low fluidity, thinly and uniformly into a mold, it is necessary to prepare an injection molding machine with high speed and high injection pressure to prevent solidification. In particular, in order to mold thin-walled resin molded products such as conductive reels into a three-layer structure, it is preferable to use a needle-type shutoff mechanism, which has low pressure loss and can be controlled at high speed, as the shutoff mechanism of the main cylinder of the injection molding machine 100 shown in Figure 6(a), and a rotary-type shutoff mechanism, which also has low pressure loss, as the shutoff mechanism of the sub-cylinder. The specifications of the shutoff mechanism and injection pressure can be appropriately designed according to the molding conditions, etc. Figure 6(b) shows a schematic diagram of a needle-type shutoff mechanism using a needle valve, and Figure 6(c) shows a schematic diagram of a rotary-type shutoff mechanism using a rotary valve. The inner nozzle is the flow path for the skin material and core material, respectively, and is a component that connects each cylinder to the nozzle. The nozzle is the same flow path for the skin material flowing from the outer circumference of the inner nozzle and the core material injected from the inner nozzle, and is a component that comes into contact with the mold.

[0023] Figure 7 is a schematic cross-sectional view showing the state in which the core material is partially exposed from the skin material during the molding of the protruding portion 11 of the side plate 10. In sandwich molding, the tip portion 91 of the protruding portion 11 is molded so that the core layer 30 is exposed. That is, in the sandwich molding process in the order of steps I, II, III, and IV shown in Figure 7, a breakthrough phenomenon is intentionally caused at the tip portion of the protruding portion 11, and the core layer 30 is exposed at the tip portion 91 of the protruding portion 11, which is the planned joining point. This makes it possible to heat-weld the exposed core materials 30 together when the two side plates 10 are brought into contact with each other.

[0024] In Figure 7, when the core material reaches the leading edge of the skin material flow (Step I), it cannot break through the skin layer 20 because of the presence of a solidified layer of skin material. Instead, the core material flows towards the unsolidified skin material, becoming thicker (Step II). However, the solidified layer of skin material remains intact, causing the core material to expand like a balloon at the leading edge of the flow (Step III). This stretches and breaks the solidified layer, exposing the core material at the leading edge of the flow (Step IV). While breakthrough phenomena are typically recognized as defects during molding, by intentionally causing this breakthrough phenomenon at an arbitrary location (in this embodiment, the leading edge 91 of the protruding portion 11), a three-layer structure is created in which the core layer 30 is exposed from the skin layer 20.

[0025] Figure 8 is a photograph of a prototype conductive reel, showing the core layer 30 exposed from the skin layer. At the tip portion 91 of the protruding portion 11 enclosed by the dotted line in the figure, the white-colored core layer 30 is exposed from the black-colored skin layer 20. In a three-layer structure formed by sandwich molding, the core layer can be exposed from its tip portion.

[0026] The welding strength is higher in the conductive resin of the core layer 30 than in the conductive resin of the skin layer 20, which firmly bonds the protruding portion 11 and improves the strength and durability of the winding core. In this embodiment, a welding strength of 700N or more can be secured by utilizing the breakthrough phenomenon.

[0027] Figure 9 shows experimental data illustrating the conductive properties of the conductive skin layer in the conductive reel 1 of the present invention. Figure 9(a) is a cross-sectional photograph of the prototype conductive reel, Figure 9(b) is a magnified portion of the skin layer and core layer in the cross-sectional photograph, Figure 9(c) shows the distribution (mapping) data of carbon as a conductive material, and Figure 9(d) shows the measurement results of the surface resistivity. The measurement evaluated the surface resistivity of the skin layer 20 in accordance with JIS standards. As a result, the range of surface resistivity in which the desired conductivity can be ensured in the skin layer (e.g., 10) 4 -10 9 It was confirmed that the ratio Ω / □ was ensured. Furthermore, it was confirmed that carbon was uniformly dispersed in the skin layer 20. As a result, the entire reel can be provided with antistatic properties, and electrostatic discharge damage to the electronic components and semiconductors being transported can be effectively prevented. Figure 9(d) shows, as comparative data, the measured surface resistivity of a conductive reel having a three-layer structure by sandwich molding according to the present invention (with a core material filling rate of 10%), as well as conventional conductive reels using a single material (virgin material only, recycled material only). By increasing the material ratio (filling rate) of the core material to the skin material, material costs can be reduced, and by increasing the proportion of recycled material used as the core material, the product becomes more environmentally friendly.

[0028] As described above, the conductive reel 1 of the present invention is composed of a three-layer structure consisting of a conductive skin layer and a non-conductive core layer, enabling simultaneous achievement of conductivity, lightweight design, and reduced manufacturing costs. In particular, by utilizing sandwich molding, it becomes possible to achieve both conductivity and cost reduction, which was difficult with a single material, and furthermore, a robust bonding method is provided by exposing the core layer at protruding portions. [Explanation of Symbols]

[0029] 1: Conductive reel, 10: Side plate, 11: Protruding part, 90: Through hole, 91: Tip of the protruding part, 100: Injection molding machine

Claims

1. A conductive reel on which a carrier tape for housing electronic components is wound, A resin molded product formed by sandwich molding into a three-layer structure consisting of a core layer and skin layers on both sides thereof, The core layer is made of a non-conductive resin that does not have conductivity, and the skin layer is made of a conductive resin that has conductivity. The conductive reel has two disc-shaped side plates, each of which has a protruding portion that extends from its center in the direction of the rotation axis, and the tip portions of the protruding portions are joined together so that the side plates are arranged opposite each other with at least the width of the carrier tape separating them, thereby forming the conductive reel. A conductive reel characterized in that the core layer is exposed at the tip of the protruding portion, the exposed core layer covers the skin layer, and the exposed core layers are joined together.

2. The conductive reel according to claim 1, characterized in that the non-conductive resin is a recycled material produced by a recycling process.

3. The conductive reel according to claim 1, characterized in that the conductive resin is a mixed material in which a recycled material produced by reprocessing a non-conductive resin to the extent that it has the required conductivity is mixed.

4. In a method for manufacturing a conductive reel around which a carrier tape for housing electronic components is wound, The conductive reel has two disc-shaped side plates, each of which has a protruding portion that extends from its center in the direction of the rotation axis, and the side plates are joined together with the protruding portions facing each other so that they are arranged facing each other with at least the width of the carrier tape separating them. The side plate is formed by sandwich molding into a three-layer structure consisting of a non-conductive core layer and conductive skin layers on both sides thereof. Furthermore, the method for manufacturing a conductive reel is characterized in that, in the sandwich molding process, the tip portion of the protruding portion of the side plate is injection molded so that the core layer is exposed.

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