JPH05329880A - Manufacturing method of composite housing - Google Patents

Abstract

PURPOSE:To obtain a thin-wall case having a required impact strength by a method wherein a mold is composed of a core and a cavity, an elastic sheet provided with a plurality of tapered holes or lugs is positioned on the inner surface of the cavity, and an injection molding is carried out. CONSTITUTION:A mold is composed of a core and a cavity. An elastic body 2 provided with tapered holes or an elastic body 5 provided with tapered lugs is inserted in the inner surface of the cavity to be positioned thereon. After that, a resin 3 is injected from a gate and cured. In this manner, a composite case having a good adhesion can be obtained. As the elastic bodies 2, 5, a silicone rubber or fluoro rubber sheet 0.8mm or more thick is preferably used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a composite housing for electronic equipment. In recent years, electronic devices have been reduced in size and weight, but the same applies to housings, which require thinning.

Here, the requirements for the housing for electronic equipment are high strength and excellent impact resistance.

[0003]

2. Description of the Related Art AB has hitherto been used as a resin having excellent impact resistance.
S (acrylonitrile butadiene styrene) resin and polycarbonate resin have been used.

Since these resins are inexpensive, they are generally used as casing materials for electronic equipment. However, since the resin has insufficient fluidity, molding becomes difficult as the housing becomes thinner.

Therefore, in place of these resins, attention has been paid to polyamide and PBT (polybutylene terephthalate), which have relatively good fluidity. However, although these resins have the required strength, they have insufficient impact resistance and do not meet the necessary conditions.

As a countermeasure against this, mixing rubber into a resin as a filler was also studied, but since the mixing amount of rubber is limited, the required impact resistance cannot be obtained, and the thin type However, the molding itself is difficult due to this.

[0007]

The housing is required to be thin due to the downsizing and weight reduction of electronic equipment, and a method for manufacturing a thin housing having a required impact strength without lowering the strength of resin is provided. The challenge is to put it into practical use.

[0008]

[Means for Solving the Problems] The above-mentioned problem is to position an elastic sheet having a plurality of tapered holes or projections on the inner surface of a cavity mold of an injection molding die including a core mold and a cavity mold. This can be solved by constructing a method for manufacturing a composite housing, which is characterized in that the mold is closed and resin injection molding is performed thereafter.

[0009]

Function: Strength and impact resistance are contradictory properties, and there is no resin excellent in both. Therefore, the inventors considered a composite as a method of satisfying both properties.

Here, a resin having good fluidity is selected as a resin having strength, and a rubber elastic body is selected as a resin imparting impact resistance, and the rubber elastic body is laminated to form a composite body. Satisfied.

Since the rubber elastic body and the resin are completely different in material and have different thermal expansion coefficients, a mechanical interlocking mechanism is required to realize a composite housing having excellent adhesiveness. The inventors have provided a rubber elastic body to be joined with a tapered hole or projection, and in this state, resin is injection molded to be integrated.

FIG. 1 is a cross-sectional view showing the structure of the composite housing thus formed. FIG. 1A shows an elastic body 2 having a tapered hole 1 on its inner surface and an injection molding of a resin 3 on the elastic body 2. The adhesiveness is improved by filling the resin 3 into the tapered hole 1, and FIG. 2B shows the injection molding of the resin 3 into the elastic body 5 having the tapered protrusion 4. Then, the taper-shaped projection 4 is tightened with the cured resin 3 to improve the adhesion.

FIG. 2 is a cross-sectional view showing a method for molding a composite housing according to the present invention. The mold 6 is composed of a core mold 7 and a cavity mold 8. The elastic body 2 having a tapered hole or the elastic body 5 having a tapered protrusion is inserted into the inner surface for positioning. (A in the same figure as above) Next, a resin 10 is injection-molded from the gate 9 and cured to obtain a composite housing having good adhesiveness. (As shown in FIG. 9B) In the present invention, as a method having both strength and impact resistance, a resin is injection-molded into an elastic body having a mechanical meshing mechanism so as to be integrated. Obtainable.

As a result of repeated trials and examinations, it is necessary that the shape of the tapered hole or protrusion is simple such as circular, triangular, or quadrangular so that there is no acute angle. This is to avoid local concentration of stress.

[0015]

[Examples] Polyamide was used as the resin, and three types of silicone rubber, fluorine rubber, and natural rubber were used as the elastic body, and elastic sheets having thicknesses of 0.8 mm, 1.0 mm, and 1.2 mm were made.

Then, as shown in FIG. 2, the elastic sheet was positioned in the cavity mold 8 and polyamide injection molding was performed. The conditions of injection molding are molding temperature 280 ℃ and molding pressure 200 Kg / cm ² .

Then, a test piece conforming to JIS-K7110 No. 2A was prepared from the molded product and subjected to an Izod impact test to examine the impact resistance. Table 1 shows this result. In the case of silicone rubber and fluororubber, if the sheet thickness is 0.8 mm or less, the sheet may be broken by the molding pressure, so the effect is low.
If it is 0.8 mm or more, impact resistance is improved.

A drop test was conducted on a molded product having a size of 25 × 20 mm and a thickness of 2.5 mm with a 1.5 Kg iron plate as a weight. In this case, an iron plate having a thickness of 1 cm was laid on the falling surface, and the height at which a crack having a length of 1 mm or more was generated in the falling resin part was measured, and the result was in agreement with the result of the Izod impact test.

[0019]

[Table 1]

[0020]

According to the present invention, it is possible to put into practical use a thin housing for electronic equipment which has both strength and impact resistance required by the practice of the present invention.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a composite housing.

FIG. 2 is a cross-sectional view showing a method for forming a composite housing.

[Explanation of symbols] 1 tapered hole 2, 5 elastic body 3, 10 resin 4 tapered protrusion 6 mold 7 core type 8 cavity type

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication H01L 23/29 23/31 // B29K 27:12 83:00 B29L 31:34 4F (72) Invention Person Takashi Muratani 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Within Fujitsu Limited (72) Inventor Koichi Kimura 1015 Kamitadanaka, Nakahara-ku, Kawasaki, Kanagawa Inside Fujitsu Limited

Claims (2)

[Claims] 1. An elastic sheet having a plurality of tapered holes or projections inside is positioned on the inner surface of a cavity mold of an injection molding mold including a core mold and a cavity mold, and then the mold is closed. A method for manufacturing a composite housing, characterized by performing resin injection molding. 2. The method for manufacturing a composite housing according to claim 1, wherein the elastic sheet is made of silicone rubber or fluororubber having a thickness of 0.8 mm or more.