Method of manufacturing a case for electronic component

Abstract: Contact member 21A, 21B is fixed to contact member holding board 26A, 26B by pushing-in and caulking works. Then, a box-shape case 29 is formed by an insert-moulding process with insulating resin so that the contact member holding board 26A, 26B is fixed at the bottom of case 29, with terminal 23A, 23B placed extruding outside the case while contact part 22A, 22B inside. A case for electronic component is thus manufactured. The use of contact member holding board 26A, 26B eliminates moulds of complicated structure, making the manufacture of case for electronic component having connecting terminals easy by an insert-moulding process.

Description: FIELD OF THE INVENTION The present invention relates to an insulating case comprising contact members having terminals, which case being used for switch and other electronic components, and to a method of manufacturing such case. BACKGROUND OF THE INVENTION Taking a case of a switch as an example to represent the prior art case for electronic component, the manufacturing method is described hereunder referring to Fig.5, a perspective view, and Fig.6, Fig.7, both cross sectional views. In a box-shape case 1 made of thermosetting resin having a square hole 2A and a square hole 2B, a contact member 3A comprised of a contact part(contact stud) 4A at the top and a terminal 5A at the bottom, and a contact member 3B comprised of a contact part(movable contact member holding section) 4B at the top and a terminal 5B at the bottom, are inserted respectively into the holes from the inside of case 1 as deep as the middle step 6A, 6B. And then, a caulking step 7A, 7B extruding outside the case 1 is spreaded for caulking, as shown in Fig.6. The contact members 3A and 3B are fixed to case 1 by the caulking work. Further, a bonding agent 8 is applied around the caulking step 7A, 7B and the square hole 2A, 2B and hardened, in order to prevent soldering flux used when connecting a lead wire(not shown) to terminal 5A, 5B from infiltrating through the gap of square hole 2A, 2B to contact part 4A, 4B. Then, as shown in Fig.7, a movable contact member 9 is coupled on the hollow of movable contact member holding section 4B from the top opening of case 1. An operating rod 11 comprising an elastic arm 10 is provided pressing the movable contact member 9 from the above, and a lid 12 is fixed on the case 1. A switch is thus completed. Along with the recent trends towards the smaller and the lower cost electronic appliances, electronic components constituting such appliances are strongly requested to be compact and inexpensive. A case for electronic component as described above, however, requires additional processing steps for applying and hardening bonding agent 8 in order to prevent the infiltration of flux, which result in an extra cost for additional manufacturing processes. Furthermore, the terminal 5A, 5B requires an extra length corresponding to an area needed for applying the bonding agent 8. This creates an extra height to the overall height of an electornic component. Meanwhile, if one intends to manufacture a box-shaped case 1 comprising the above described contact member 3A, 3B by an insert-moulding method with an aim to increase the productivity and reduce the cost, use of very complicated moulds is inevitable for holding the contact member 3A, 3B, because the contact part 4A, 4B is larger than the part to be buried into the square hole 2A, 2B. Furthermore, if a possible slanting of the contact member caused by softening of the bottom of case 1 due to heat applied when soldering a lead wire is to be avoided the case 1 needs to be made with a thermosetting resin. The thermosetting resin does not fit to an insert-moulding method employing moulds of very complicated structure. Therefore, it was very difficult to manufacture the above described box-shape case 1 having contact member 3A, 3B through the insert-moulding method. SUMMARY OF THE INVENTION The present invention is intended to present a case for electronic component. The present invention is also intended to present a method of manufacturing said case, that is suitable for reducing the overall size as well as the cost. These aims are achieved by a case according to claim 4 and by a method according to claim 1. According to the invented method of manufacturing a case for electronic component, a contact member comprised of a contact part at the top and a terminal at the bottom is fixed perpendicular to a contact member holding board made of metal by pushing into the latter's hole and caulking, and then the contact member holding board is insert-moulded with the board placed at the bottom of box-shaped case whose top is open. In this way, a case for electronic component is produced, with which case only the terminal of contact member is extruding outside the case while the contact part is located inside the case. Through a manufacturing method according to the present invention, a case for electronic component in which a contact member having contact part is fixed at the bottom is easily available by insert-moulding method, without necessitating moulds of complicated construction. BRIEF DESCRIPTION OF THE DRAWINGS Figs.1 through 4 are for explaining an invented method of manufacturing a case for electronic component, being a preferred embodiment of the present invention; Fig.1(a) is a perspective view showing the appearance of contact member and contact member holding board, Fig.1(b) is a perspective view showing the contact member fixed on the contact member holding board, Fig.1(c) is a perspective view showing a part the case for switch mounted with the contact member, Fig.2 is a cross sectional view showing the contact member fixed to the contact member holding board, Fig.3 is a cross sectional view of moulds used for the insert-moulding, Fig.4 is a cross sectional view showing a part of the case for switch having contact members. Figs.5 through 7 are for explaining a prior art method of manufacturing a case for electronic component; Fig.5 is a perspective view of the case exploded, Fig.6(a) is a lengthwise cross sectional view of the case, Fig.6(b) is a cross sectional view at A-A of Fig.6(a), Fig.7 a cross sectional view showing a state of the case with switching members assembled in. DESCRIPTION OF THE PREFERRED EMBODIMENTS A case for a switch comprising two contact members is described hereunder as one of the preferred embodiments of the present invention, referring to Fig.1 through Fig.4. Two pieces of contact members 21A and 21B are made of metal plate having good electro-conductivity such as copper, brass, and contact member holding boards 26A and 26B are made of iron or other metal plate having the same thickness as the contact members 21A, 21B. Contact member 21A comprises a contact part (contact stud) 22A at the top and a terminal 23A at the bottom. Contact member 21B comprises a contact part(contact member holding part) 22B at the top and a terminal 23B at the bottom. Between the contact part 22A, 22B and the terminal 23A, 23B, there are a middle step 24A, 24B for acting as the stopper when pushing-in and a caulking step 25A, 25B. As the first processing step, contact member 21A, 21B is pushed into a holding hole 27A, 27B of contact member holding board 26A, 26B down to the step 24A, 24B, as shown in Fig.1(b). And then, as shown in Fig.2, the caulking step 25A, 25B extruding from the rear surface of contact member holding board 26A, 26B is caulked. Through the process steps of pushing-in and caulking, the contact member 21A, 21B is fixed perpendicular to contact member holding board 26A, 26B. Then, as shown in Fig.3, the contact member holding boards 26A and 26B, having respectively the contact members 21A and 21B, are placed, providing an insulating distance, vertically between moulds 28A and 28B, to be insert-moulded with a thermoplastic insulation resin. Through the above insert-moulding process, a box-shaped case 29 for a switch is produced, wherein the contact member holding boards 26A and 26B are fixed at the bottom with contact parts 22A and 22B locating inside while terminals 23A and 23B extruding outside, as shown in Fig.1(c) and Fig.4. For completing a switch with the case 29, a movable contact member and an operating rod are assembled on the case 29, and then the top opening of case 29 is closed with a lid, in the same way as in the prior art shown in Fig.7. As shown in Fig.3, a press pin(s) 31 is provided in the mould 28B for holding contact member holding board 26A, 26B in place, which pin 31 being equipped with a spring 30 so as the pin 31 is pushed back to the outside of mould 28B by the pressure of resin injected. By this constitution, the holding board 26A, 26B is prevented from being left exposed due to no supply of resin at an area corresponding to the press pin 31, after the insert-moulding is finished. It is therefore preferred to use a press pin 31 equipped with spring 30. The thickness of contact member 21A, 21B and the thickness of contact member holding board 26A, 26B should preferably be identical to each other, in view of the processing ease at the pushing-in and caulking, as well as the mould life and cost. In a case where the thickness of contact member 21A, 21B is too small relative to the thickness of contact member holding board 26A, 26B the width of holding hole 27A, 27B becomes very small, making the push-in work difficult. Contrary, if contact member 21A, 21B is thick and contact member holding board 26A, 26B is thin the contact member becomes costly and the strength of contact member holding board becomes weak. Therefore, it is preferred that the thicknesses of the two items are almost identical. Because in the invented method of manufacturing a case for electronic component the contact member is placed on moulds in a state being attached to a contact member holding board, structure of the moulds may be simplified; which enables the manufacture by insert-moulding process. Therefore, the volume production at lower cost becomes easy. The effectiveness of the invented method becomes especially significant when manufacturing a case for electronic component in which a plurality of contact members, being insulated to each other, are disposed at the bottom. In the invented method, structure of the moulds is quite simplified and the manufacturing becomes much easier as compared with prior art production methods. In a manufacturing method according to the present invention, the contact member is fixed to the contact member holding board by a push-in method, and the contact member holding board is fixed to the bottom of case by an insert-moulding process; therefore, the contact part and the terminal are separated by the contact member holding board and the bottom of case. This avoids the infiltration of flux to contact part when soldering a lead wire to terminal; as a result, the application of bonding agent around the terminal turns out to be unnecessary. Furthermore, a section corresponding to the area for applying bonding agent can be eliminated, and the bottom thickness of case can be made thinner as the contact member holding board plays an enforcement role. These altogether contribute to make the overall size of case smaller. As the contact member holding board works also as a heat radiating board, the possible tilting of contact member caused by softened case bottom due to soldering heat is prevented even if a thermoplastic material is used for the case. Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is not to be interpreted as limiting. Various alterations and modifications will no doubt become apparent; for example, besides the thermoplastic resin a thermosetting resin may be used for the case, the invented method may be utilized also for manufacturing other types of cases, besides a case for switch, for electronic component comprising different kinds of terminals.

Claims: A method of manufacturing a case for electronic component comprising the steps of: fixing a contact member comprised of a contact part at the top and a terminal at the bottom perpendiculaly to a contact member holding board made of metal and having a hole, by pushing said contact member into the hole of said contact member holding board and by caulking a middle part of said contact member; and forming a box-shape case with an insulating resin by insert-moulding so that said contact member holding board is fixed at the bottom of the box-shape case having opening upward, with said terminal placed outside the box-shape case while said contact part inside. The method of manufacturing a case for electronic component by insert-moulding as claimed in Claim 1, wherein said contact member holding board on which a contact member is attached is provided in pluralities, and said plural contact member holding boards are disposed insulated to each other. The method of manufacturing a case for electronic component as claimed in either Claim 1 or Claim 2, wherein said contact member and said contact member holding board are made of metal sheet the thicknesses of which are identical. A case for electronic component comprising: a contact member comprised of a contact part at the top and a terminal at the bottom; a contact member holding board made of metal for perpendicularly holding and fixing said contact member at a point between said contact part and said terminal; and an insulating box-shape case made by an insert moulding process so that said contact member holding board is fixed at the bottom, with said contact part placed inside the case and said terminal extruding outside. The case for electronic component as claimed in Claim 4, wherein said contact member holding board on which a contact member is attached is provided in pluralities and said plural contact member holding boards are disposed insulated to each other. The case for electronic component as claimed in either Claim 4 or Claim 5, wherein said contact member and said contact member holding board are made of metal sheet the thicknesses of which are identical.

Inventors: KUBOKI YASUO, KUDO YASUCHIKA, NAKASE YUSHO, KUBOKI, YASUO, KUDO, YASUCHIKA, NAKASE, YUSHO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1996
Main classification: H01H11
IPC codes: H01H11, H01H9, H05K5