JP5786506B2 - Manufacturing method of housing - Google Patents

Description

  The present invention relates to a method for manufacturing a housing.

  Electronic devices such as mobile phones, PDAs (Personal Digital Assistants), notebook personal computers, and portable audio devices are becoming smaller and lighter. Along with this, thinning and weight reduction of electronic device housings are also required.

  The housing for electronic devices has not only a role of storing electronic components, but also a role of a housing component that protects electronic components from impacts. For this reason, the housing for electronic devices is also required to have high strength.

  Generally, the housing of an electronic device has a box-shaped base material and auxiliary members such as bosses and ribs arranged inside the base material. For example, by providing a screw boss inside the base material, the electronic component can be fixed to the housing without exposing the screw to the outer surface of the housing. Moreover, the strength of the housing is ensured by providing the ribs on the inner side of the base material, and the thickness of the base material can be reduced to reduce the weight.

  As a manufacturing method of such a casing, there are, for example, a method of integrally forming the base material and the auxiliary member by injection molding, and a method of separately manufacturing the base material and the auxiliary member and bonding them with an adhesive.

Japanese Patent Laid-Open No. 11-70796 Japanese Patent Laid-Open No. 5-92546 Japanese Unexamined Patent Publication No. 7-98566

  An object of the present invention is to provide a method of manufacturing a casing that includes auxiliary members such as bosses and ribs and that can manufacture a thin and lightweight casing relatively easily.

According to one aspect of the disclosed technology, a process of applying a rubber-based solvent-type adhesive to which thermally expanded microcapsules are added to the surface of a sheet formed of any of polyolefin, polyamide, and fluororesin, and a vacuum Using a pressure forming machine, a vacuum forming machine or a pressure forming machine, the sheet is brought into close contact with the surface of the base material and the adhesive is transferred to the surface of the base material. And a step of forming an auxiliary member by injecting a thermoplastic resin to a portion to which the adhesive is attached.

  According to the one aspect described above, auxiliary members such as bosses and ribs are provided, and a thin and lightweight housing can be manufactured relatively easily.

Drawing 1 is a mimetic diagram (the 1) explaining the manufacturing method of the frame concerning an embodiment. Drawing 2 is a mimetic diagram (the 2) explaining the manufacturing method of the frame concerning an embodiment. Drawing 3 is a mimetic diagram (the 3) explaining the manufacturing method of the frame concerning an embodiment. Drawing 4 is a mimetic diagram (the 4) explaining the manufacturing method of the frame concerning an embodiment. Drawing 5 is a mimetic diagram (the 5) explaining the manufacturing method of the frame concerning an embodiment. FIG. 6 is a diagram showing the relationship between the adhesive application thickness and the adhesive strength.

  Hereinafter, before describing the embodiment, a preliminary matter for facilitating understanding of the embodiment will be described.

  As described above, as a method for manufacturing a housing for an electronic device, a method of integrally forming a base material and an auxiliary member by injection molding, a method of separately manufacturing a base material and an auxiliary member, and bonding them with an adhesive, etc. There is.

  In injection molding, a housing having bosses and ribs can be manufactured relatively easily and at low cost. However, in the injection molding, it is difficult to reduce the thickness of the base material portion, and it is difficult to further reduce the weight of the casing.

  On the other hand, in the method in which the base material and the auxiliary member are separately manufactured and joined, a metal plate or the like having high strength can be used as the base material, but the weight of the housing can be reduced. However, this method requires a step of applying an adhesive to the base material and a step of placing an auxiliary member on the adhesive, but at present, a method of easily joining the auxiliary member inside the box-shaped base material. Has not been established, and there is a drawback that the manufacturing cost becomes high.

  In the following embodiments, a method of manufacturing a casing that includes auxiliary members such as bosses and ribs and that can manufacture a thin and lightweight casing relatively easily will be described.

(Embodiment)
1-5 is a schematic diagram explaining the manufacturing method of the housing which concerns on embodiment to process order.

  First, the process shown in FIG. 1 will be described. In the process shown in FIG. 1, a flexible sheet 11 is prepared, and an adhesive 12 is applied on a predetermined region of the sheet 11 by a screen printing method using a printing mask 13. The application thickness of the adhesive 12 is, for example, 30 μm.

  In this embodiment, as will be described later, the adhesive 12 applied to the sheet 11 is transferred to the inside of the base material 14. For this reason, it is required that the adhesive 12 can be applied to the sheet 11 with high accuracy, the adhesive 12 does not bleed or shift in position before transfer, and the adhesive 12 can be easily peeled off during transfer. The

  In the present embodiment, it is assumed that the sheet 11 is formed of a resin such as polyolefin, polyamide, or fluororesin. These resins can satisfy the above requirements and are not dissolved in the organic solvent contained in the adhesive 12.

  The sheet 11 may be formed of, for example, a resin selected from polyethylene (PE) and polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA), and polytetrafluoroethylene (PTFE).

  The sheet 11 is also required to have flexibility to follow the inner surface shape of the base material 14 when the adhesive 12 is transferred to the base material 14. If the thickness of the sheet 11 exceeds 100 μm, sufficient flexibility may not be obtained. Moreover, when the thickness of the sheet 11 is less than 50 μm, the sheet 11 may be torn when the adhesive 12 is transferred to the base material 14. For this reason, it is preferable that the thickness of the sheet | seat 11 shall be 50 micrometers-100 micrometers.

  The adhesive 12 is required to have an appropriate adhesive force with respect to the sheet 11. Since the adhesive 12 is separated from the sheet 11 in a subsequent process, it is not preferable that the adhesive force to the sheet 11 is too strong.

  In the present embodiment, as the adhesive 12, for example, a rubber solvent type adhesive in which styrene / butadiene / styrene rubber, nitrile rubber, chloroprene rubber or the like is dissolved in an organic solvent is used. These rubber-based solvent type adhesives have an appropriate adhesive force to the sheet 11 formed of the above-described resin.

  Moreover, these rubber-based solvent-type adhesives solidify to lose adhesive strength when dried, but have a so-called hot-melt property in which the adhesive strength is recovered by heating even after solidification. An adhesive having hot melt properties is easy to handle because it does not have to worry about the time (open time) from application to bonding.

  Furthermore, since the adhesive having hot melt property has almost no tackiness after being solidified, it is not necessary to attach a separator for preventing the adhesion of dust to the surface of the adhesive.

  In this embodiment, the adhesive 12 is applied to the sheet 11 by screen printing. However, the method of applying the adhesive 12 is not limited to screen printing, and other methods such as lithographic printing or plateless printing. May be adopted. Moreover, in order to ensure the application | coating thickness of the adhesive agent 12, the adhesive agent 12 may be printed in multiple times and an adhesive bond layer may be piled up.

  Next, the process shown in FIG. 2 will be described. In the process shown in FIG. 2, the adhesive 12 applied to the sheet 11 is transferred to the base material 14 using a vacuum / pressure forming machine 15.

  The base material 14 is formed by pressing a metal plate such as an aluminum alloy plate or a magnesium alloy plate into a box shape. Here, the base material 14 shall have a rectangular-shaped baseplate part and the side-plate part which stands | starts up substantially perpendicularly from the edge of a baseplate part.

  In addition, the base material 14 is not limited to the pressed metal plate, For example, what was produced by FRP (Fiber Reinforced Plastics) etc. which used glass fiber or carbon fiber etc. may be used.

  The vacuum / pressure forming machine 15 includes a mold 18 provided with a concave portion on which the base material 14 is disposed on the upper side, and a sheet fixing member 16 that fixes the sheet 11 with the edge of the sheet 11 interposed therebetween. A heater 17 for heating the sheet 11 is disposed above the mold 18. Further, the space inside the vacuum / pressure forming machine 15 is connected to a vacuum pump (not shown) via a valve 19.

  In order to transfer the adhesive 12 to the base material 14, the base material 14 is disposed in the recess of the mold 18 as shown in FIG. 2, and the sheet 11 is positioned and disposed on the base material 14. And after fixing the sheet | seat 11 on both sides of the edge of the sheet | seat 11 with the metal mold | die 18 and the sheet | seat fixing member 16, the vacuum pump is operated and the inside of the vacuum pressure forming machine 15 is pressure-reduced to predetermined pressure. In addition, power is supplied to the heater 17 to heat the sheet 11 to, for example, 80 ° C. to 100 ° C. By this heating, the adhesive force of the adhesive 12 applied to the sheet 11 is restored.

  Instead of heating the sheet 11 by the heater 17 in the vacuum / pressure forming machine 15, the sheet 11 may be heated before being placed in the vacuum / pressure forming machine 15. Alternatively, a heater may be incorporated in the mold 18 to heat the sheet 11 from the mold 18 side.

  Next, air is introduced into the upper side of the sheet 11 in the vacuum / pressure forming machine 15. As a result, a pressure difference is generated between the upper side and the lower side of the sheet 11, so that the sheet 11 adheres to the inner surface of the base material 14. At this time, a pressure higher than the atmospheric pressure may be applied to the upper side of the sheet 11.

  Thereafter, when the sheet 11 is sufficiently in close contact with the inner surface of the substrate 14, the power supply to the heater 17 is stopped. And it waits until temperature falls and sufficient adhesive force between the base material 14 and the adhesive agent 12 is ensured.

  Next, the base material 14 is removed from the vacuum / pressure forming machine 15, and the sheet 11 is peeled off from the base material 14. At this time, since the adhesive 12 is more strongly bonded to the base material 14 than the sheet 11, the adhesive 12 and the sheet 11 can be easily separated. In this way, the adhesive 12 is transferred to the inner surface of the substrate 14.

  FIG. 3 is a schematic cross-sectional view showing the base material 14 after transferring the adhesive 12. As shown in FIG. 3, in this embodiment, it is assumed that the adhesive 12 is transferred onto a predetermined region of the bottom plate portion of the base material 14 and the inner surface of the side plate portion.

  In this embodiment, the adhesive 12 is transferred from the sheet 11 to the inner surface of the base material 14 using the vacuum / pressure forming machine 15, but instead of the vacuum / pressure forming machine 15, a vacuum forming machine or a pressure forming machine is used. It may be used.

  Next, the process shown in FIG. 4 will be described. In the process shown in FIG. 4, the base material 14 is disposed between the molds 21 a and 21 b of the injection molding machine 20. When the molds 21a and 21b are combined, a cavity (mold space) 22 having a desired auxiliary member shape is formed. The adhesive 12 is transferred to the base material 14 at a position corresponding to the cavity 22.

  When a molten thermoplastic resin is injected into the cavity 22 from the injection machine 23, the thermoplastic resin and the adhesive 12 are brought into close contact with each other by the pressure at the time of injection. Also, the adhesive 12 is heated by the thermoplastic resin to recover the adhesive force. Thereafter, when the thermoplastic resin is cured in the cavity 22, the thermoplastic resin (auxiliary member) in the cavity 22 and the base material 14 are firmly bonded via the adhesive 12.

  Note that the thermoplastic resin injected into the cavity 22 is not particularly limited as long as it has a high adhesive force to the adhesive 12. For example, polyolefin or polyester can be used as the thermoplastic resin.

  Next, the molds 21a and 21b are opened and the base material 14 is taken out. In this way, as shown in the schematic perspective view of FIG. 5, the housing 1 is completed in which auxiliary members such as the screwing boss 2 and the reinforcing rib 3 are provided inside the base material 14.

  As described above, according to the present embodiment, an adhesive is attached to the inner surface of the box-shaped base material 14 using a printing method and a transfer method, and a resin is applied to the portion where the adhesive is attached by an injection molding machine. By injecting, auxiliary parts such as the boss 2 and the rib 3 are formed. For this reason, the box-shaped housing 1 having auxiliary members such as the boss 2 and the rib 3 can be manufactured relatively easily.

  In the present embodiment, for example, by forming the rib 3 on the inner side of the base material 14, sufficient strength can be ensured even if the thickness of the base material 14 is reduced, and the casing 1 can be reduced in weight. it can. Furthermore, by forming the boss 2 for screwing on the inner side of the base material 14, it is possible to avoid exposing a screw or the like for fixing the electronic component to the outside of the housing 1.

  Furthermore, in this embodiment, the base material 14 and the auxiliary member can be made of different materials. For this reason, for example, by using a thin metal plate as the base material 14, the casing 1 can be further reduced in weight.

  A filler may be added to the adhesive 12 in order to adjust the elongation rate of the adhesive 12, suppress foaming, or adjust the coating thickness. In that case, since the wettability and dispersibility with respect to the adhesive agent 12 are good, it is preferable to add a silicic acid-based filler such as silica, glass balloon, and glass flake.

  Moreover, you may add a commercially available thermal expansion microcapsule to the adhesive agent 12 as a filler. The thermal expansion microcapsule is one in which an expansion agent is filled inside an outer shell made of a resin such as acrylic, and the expansion agent expands when heat is applied.

  When a thermal expansion microcapsule is added to the adhesive 12, the coating thickness of the adhesive 12 can be easily adjusted. Further, for example, when the electronic device is discarded, when the casing 1 is heated to sufficiently expand the thermal expansion microcapsule contained in the adhesive 12, the base material 14 and the auxiliary member can be easily separated, Recycling of materials becomes easy.

  Note that it is preferable to use thermal expansion microcapsules having a thermal expansion temperature higher than the drying temperature of the adhesive 12 so that the thermal expansion microcapsules do not expand when the adhesive 12 is dried.

  Next, a description will be given of the result of actually manufacturing the casing by the above-described method and examining the bonding strength between the base material and the auxiliary member.

Example 1
The pellets of high-density polyethylene (Hi-Zex 5100B manufactured by Prime Polymer Co., Ltd.) were heated to 270 ° C. and dissolved, and then rolled with a roller mill to produce a sheet 11 having a thickness of 60 μm.

  Moreover, 70 g of isophorone (solvent) and 2 g of silica having an average particle diameter of 2 μm were added to 100 g of a commercially available chloroprene rubber adhesive (CS4503F manufactured by Cemedine Co., Ltd.) to obtain an adhesive 12 for screen printing.

  And the adhesive agent 12 was printed on the predetermined area | region of the sheet | seat 11 using the 80 mesh stainless steel screen. The coating thickness of the adhesive 12 was about 30 μm. Thereafter, the adhesive 12 was solidified by holding at a temperature of 80 ° C. for about 30 minutes.

  On the other hand, a magnesium alloy plate (AZ31B) of 260 mm (vertical) × 160 mm (horizontal) × 0.5 mm (thickness) is prepared, and this magnesium alloy plate is drawn by a servo press machine to form a shallow box having a depth of 10 mm. A substrate 14 was prepared.

  And the adhesive agent 12 printed on the sheet | seat 11 was transcribe | transferred to the inner surface of the base material 14 using the vacuum pressure forming machine (refer FIG. 2). At this time, the heater 17 was energized, and the adhesive 12 was heated to 90 ° C. and held for 20 seconds.

  Thereafter, the base material 14 is placed in a mold of an injection molding machine, and a thermoplastic resin (polycarbonate) is injected to a portion where the adhesive 12 is adhered, thereby forming auxiliary members such as the boss 2 and the rib 3. (See FIG. 4). At this time, the heating temperature is 300 ° C., the injection speed is 50 mm / s, and the mold temperature is about 100 ° C.

  The side plate portion and the boss portion of the housing 1 thus manufactured were cut out and subjected to a tensile test, and the adhesive force between the base material and the resin was measured. As a result, the adhesive force between the substrate and the resin was about 6 MPa.

(Example 2)
To 100 g of a commercially available chloroprene rubber adhesive (CS4503F manufactured by Cemedine Co., Ltd.), 70 g of isophorone and 10 g of thermal expansion microcapsules having an average particle diameter of 20 μm were added to obtain an adhesive 12 for screen printing. The adhesive 12 was screen-printed on the same sheet 11 as used in Example 1. The coating thickness of the adhesive 12 was 20 μm.

  Thereafter, the adhesive was transferred to the inside of the substrate 14 in the same manner as in Example 1, and then heated at a temperature of 130 ° C. for 10 minutes. By this heating, the thermally expanded microcapsules in the adhesive 12 were expanded, and the coating thickness of the adhesive 12 was about 30 μm.

  Next, similarly to Example 1, the base material 14 was placed in a mold of an injection molding machine, and a thermoplastic resin (polycarbonate) was injected to form bosses and ribs.

  A side plate portion and a boss portion of the casing 1 manufactured as described above were cut out, a tensile test was performed, and an adhesive force between the base material and the resin was measured. As a result, the adhesive force between the substrate and the resin was about 5 MPa.

  In addition, since the housing manufactured by the method of Example 2 contains thermally expanded microcapsules in the adhesive, the thermally expanded microcapsules are further expanded by heating to, for example, 170 ° C., and the adhesive strength of the adhesive is increased. It is significantly reduced and the substrate and the resin can be easily separated.

  By the way, the adhesive strength of the adhesive is related to the coating thickness of the adhesive. FIG. 6 is a diagram showing the relationship between the horizontal axis with the adhesive coating thickness and the vertical axis with the adhesive strength.

  As can be seen from FIG. 6, in the case of an adhesive (main agent only) to which silica and thermal expansion microcapsules are not added, an adhesive force of 5 MPa or more can be secured if the coating thickness is 30 μm. Moreover, it turns out that adhesive force improves from FIG. 6 by adding a silica and a thermal expansion microcapsule to an adhesive agent (main ingredient).

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1) Applying an adhesive to the surface of the sheet;
A step of bringing the sheet into close contact with the surface of the substrate and transferring the adhesive to the surface of the substrate;
And a step of forming an auxiliary member by injecting a thermoplastic resin onto a portion of the base material to which the adhesive is adhered by an injection molding machine.

  (Additional remark 2) The said base material has a box-shaped shape, The manufacturing method of the housing of Additional remark 1 characterized by the above-mentioned.

  (Supplementary Note 3) In the step of bringing the sheet into close contact with the surface of the base material, any one of a vacuum / pressure forming machine, a vacuum forming machine, and a pressure forming machine is used. Method.

  (Additional remark 4) The said sheet | seat is formed from either polyolefin, polyamide, and a fluororesin, The manufacturing method of the housing of any one of Additional remark 1 thru | or 3 characterized by the above-mentioned.

  (Additional remark 5) The said adhesive agent has hot-melt property, The manufacturing method of the housing of any one of Additional remark 1 thru | or 4 characterized by the above-mentioned.

  (Additional remark 6) The said adhesive agent has a styrene, butadiene, styrene rubber, a nitrile rubber, or a chloroprene rubber as a main component, The manufacturing method of the housing of Additional remark 5 characterized by the above-mentioned.

  (Additional remark 7) The manufacturing method of the housing | casing of any one of additional remark 1 thru | or 5 characterized by adding the silicic acid type filler to the said adhesive agent.

  (Additional remark 8) The thermal expansion microcapsule is added to the said adhesive agent, The manufacturing method of the housing of any one of Additional remark 1 thru | or 5 characterized by the above-mentioned.

  (Additional remark 9) The said auxiliary member is the boss | hub for fixing an electronic component, or the rib for reinforcement, The manufacturing method of the housing of any one of Additional remark 1 thru | or 8 characterized by the above-mentioned.

  DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Boss, 3 ... Rib, 11 ... Sheet, 12 ... Adhesive, 13 ... Printing mask, 14 ... Base material, 15 ... Vacuum / pressure forming machine, 16 ... Sheet fixing member, 17 ... Heater, 18 ... Die, 19 ... valve, 20 ... injection molding machine, 21a, 21b ... mold, 22 ... cavity, 23 ... injection machine.

Claims (4)

Applying a rubber-based solvent-type adhesive to which thermally expanded microcapsules are added to the surface of a sheet formed of any of polyolefin, polyamide and fluororesin ;
Using a vacuum / pressure forming machine, a vacuum forming machine, or a pressure forming machine, the step of bringing the sheet into close contact with the surface of the substrate and transferring the adhesive to the surface of the substrate;
And a step of forming an auxiliary member by injecting a thermoplastic resin onto a portion of the base material to which the adhesive is adhered by an injection molding machine. The method of manufacturing a housing according to claim 1, wherein the thickness of the sheet is 50 μm to 100 μm. The said base material has a box-shaped shape, The manufacturing method of the housing of Claim 1 or 2 characterized by the above-mentioned. The said adhesive agent has hot-melt property, The manufacturing method of the housing of any one of Claim 1 thru | or 3 characterized by the above-mentioned.

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