JP2007226995A - Miniature switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniature switch having a grounding structure capable of connecting more surely and is easy to form. <P>SOLUTION: The waterproof sheet 18 of the miniature switch is provided with a conduction hole 18a. A conductive layer 22 is formed on the surface of the waterproof sheet 18 and the conduction hole 18a. This conductive layer 22 is conducted to a grounding pattern 14d provided on the substrate 10. The grounding pattern 14d is connected to a grounding through-hole pattern 14e provided on the substrate 10. This grounding through-hole pattern 14e is soldered, together with a mounting electrode at mounting. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a small switch such as a tact switch used in a portable electronic device such as a digital camera, a video camera, various AV terminals, or a mobile phone.

  Conventionally, even in a small switch such as a tact switch, a grounding portion is provided in order to prevent malfunctions and contact damage due to the influence of static electricity or the like. As a small switch having this ground portion, the one shown in FIG. 12 has been commercialized. This small switch has a metal cover 4 that covers the surface side of the mold case 2. At the lower end of the side wall portion 4a of the metal cover 4, a ground portion 4b made of a small piece protruding downward is provided, and this ground portion 4b is soldered to the ground pattern on the circuit boards of various devices when mounted. It was.

  However, since the ground part 4b as described above is a small plate-like piece perpendicular to the mounting surface, it is difficult for solder to be placed thereon, and it may become unsoldered during soldering. For this reason, there is a problem that not only the function as the ground cannot be performed, but also the function as the ground cannot be confirmed unless it is actually mounted.

  The problem to be solved by the present invention is to solve the above-mentioned conventional problems, and to provide a small switch having a ground structure that can be more reliably connected and can be easily formed.

  The small switch according to the present invention includes a waterproof sheet covering an upper surface and a substrate having an external connection terminal, and a conductive layer is provided on the waterproof sheet and in a conductive hole provided in the waterproof sheet, and the conductive hole is interposed through the conductive hole. The conductive layer is electrically connected to the ground pattern on the substrate, and the ground pattern is drawn and connected to the ground through-hole pattern provided on the substrate to form a ground terminal. The conductive layer in the small switch is formed by printing a conductive resin. The conductive layer in the conduction hole of the substrate is formed by the conductive resin printed on the waterproof sheet flowing into the conduction hole. The substrate has a corner at a position corresponding to the conduction hole, and the ground pattern is formed on the corner. Further, the substrate has a grounding through-hole portion and a through-hole portion at a position sandwiching the corner portion, and the grounding through-hole pattern is formed in the grounding through-hole portion.

  According to the present invention, since the ground terminal extending from the surface to the ground through hole pattern is formed, it can be reliably soldered in the same manner as the mounting terminal composed of other through holes. In the present invention, since the conductive layer is connected to the ground through hole pattern through the ground pattern from the conductive hole of the waterproof sheet, the conductive hole and the ground through hole can be formed without forcibly aligning each other. Each can be formed at an optimum position. Further, since the conductive layer is formed by printing a conductive resin, the conductive layer can be appropriately formed according to the shape and structure of the switch. Moreover, since the conductive layer is formed in the conduction hole by the conductive resin flowing from the waterproof sheet into the conduction hole, the conductive layer can be formed in the conduction hole without using a special manufacturing means. .

  The waterproof sheet in the small switch of the present invention is provided with a conduction hole. A conductive layer is formed in the conduction hole, and this conductive layer is brought into contact with a ground pattern provided on the substrate. This grounding pattern is connected to a grounding through hole pattern provided on the substrate, and this grounding throughhole pattern is soldered together with the mounting electrode during mounting. As described above, in the present invention, the ground terminal can be formed from the surface side of the switch to the through-hole electrode similar to the mounting terminal through the conduction hole and the grounding pattern, and thus soldering can be reliably performed. Can do.

  1 is a cross-sectional view of a main part of a small switch according to an embodiment of the present invention, and FIGS. 2 to 6 are a front side perspective view, a rear side perspective view, a plan view, a side view, and a bottom view of the small switch shown in FIG. It is. 1 is a cross-sectional view taken along the line AA in FIG. Reference numeral 10 denotes a substrate, which is composed of a substrate body 12 made of resin or the like and having insulating properties, and conductive patterns 14 formed on the front and back surfaces thereof. The substrate main body 12 has a rectangular planar shape, and through holes 12a formed of quarter-arc-shaped concave portions are provided at three of the four corners, and corner portions 12b are provided at the remaining one portion. . Further, the substrate body 12 is provided with a through-hole portion 12c formed of a half-arc-shaped concave portion and a grounding through-hole portion 12d in the vicinity of the corner portion 12b and on the side wall portion sandwiching the corner portion 12b. Yes. The through-hole portion 12c in the present embodiment is for forming a contact point with a dummy electrode or a spring provided in a circuit of the device for increasing the fixing force by soldering.

  On the other hand, various pattern configurations are applied to the conductive pattern 14 depending on the use and type of the switch. Here, a relatively simple pattern configuration as shown in FIG. 7 will be described. The conductive pattern 14 includes a central fixed contact pattern 14a formed at the center of the surface of the substrate body 12, an outer peripheral fixed contact pattern 14b formed in a ring shape around the periphery, and through holes 12a and 12c and the front and back peripheral edges thereof. A through hole pattern 14c formed on the surface of the corner portion 12b, and a ground through hole pattern 14e formed in the ground through hole portion 12d and on the front and back edges thereof. Have. The center fixed contact pattern 14 a is drawn out to the back side of the substrate body 12 through a through hole 12 e provided near the center of the substrate body 12. The outer peripheral fixed contact pattern 14b is routed and connected to one of the through-hole patterns 14c. The ground pattern 14d is formed in a substantially fan shape on the surface of the corner portion 12b, and is led to and connected to the ground through-hole pattern 14e.

  Reference numeral 16 denotes a contact spring made of a tact spring having a dome shape. The outer peripheral portion of the contact spring 16 is in contact with the outer peripheral fixed contact pattern 14b, and when the central portion is pushed in and reversed, it is arranged so as to contact the central fixed contact pattern 14a. The grounding pattern 14 d is provided outside the outer peripheral fixed contact pattern 14 b and is disposed at a position where it does not contact the contact spring 16.

  Reference numeral 18 denotes a waterproof sheet that covers the contact spring 16, and has a rectangular planar shape in which four corners form quarter-arc-shaped concave portions as shown in FIG. 8. A spacer 20 surrounding the contact spring 16 is integrally formed or fixed to the periphery of the waterproof sheet 18 in the present embodiment in order to cover the contact spring 16 without difficulty. The waterproof sheet 18 is attached by covering the contact spring 16 and fixing the spacer 20 to the surface of the substrate 10. In this embodiment, the grounding pattern 14d of the substrate 10 is exposed by the conduction hole 18a formed by the arc-shaped recess corresponding to the corner 12b of the substrate 10, and a conductive layer described later is grounded from the conduction hole 18a. It is possible to connect to the pattern 14d.

  Reference numeral 22 denotes a conductive layer formed by printing a conductive resin. The conductive layer 22 is formed on the surface of the waterproof sheet 18, and at that time, a conductive resin is poured into the conductive hole 18a, so that the conductive layer 22 is also formed in the conductive hole 18a. Further, the conductive resin poured into the conduction hole 18a is received by the ground pattern 14d on the substrate 10, whereby the conductive layer 22 and the ground pattern 14d are conducted. A circular hole 23 is provided in the central portion of the conductive layer 22 so that the center of the surface of the waterproof sheet 18 appears.

  In the small switch having the above configuration, the conductive layer 22 provided in the conduction hole 18a from the surface of the waterproof sheet 18 is conducted to the ground pattern 14d. Since the ground pattern 14d is connected to the ground through-hole pattern 14e, the conductive layer 22 is connected to the ground through-hole pattern 14e. Thus, in this embodiment, the grounding through-hole portion 12d provided with the grounding through-hole pattern 14e becomes the grounding terminal 24, and when this small switch is mounted on the circuit board of the device, the grounding terminal 24 is soldered to a ground pattern such as a circuit board of the device. As a result, when a current due to static electricity or the like is generated on the switch surface, the current flows from the conductive layer 22 to the ground through-hole pattern 14e, and can be dropped from the ground through-hole pattern 14e to a ground pattern such as a circuit board of the device. it can.

  In the present embodiment, the conductive layer 22 is not formed in the center of the surface of the waterproof sheet 18 and light from a light emitting element or the like that is turned on in response to on / off of the switch is configured to be transmitted. The conductive layer 22 may be formed on the entire surface of the waterproof sheet 18.

  Further, the ground pattern 14d in the present embodiment can be disposed at almost any position as long as it is outside the outer peripheral fixed contact pattern 14b. This is the same even when a complicated contact pattern 34 as shown in FIG. 9 is formed on the substrate body 12. That is, as shown in FIG. 10 and FIG. 11, a part of a round spring 26 having a circular planar shape or a star spring 36 having a planar shape is mounted on the corner portion 12b that is originally a through hole. There is nothing. Therefore, if the ground pattern 14d is routed along one side of the substrate body 12 from the corner 12b, the ground pattern 14d can be easily formed by avoiding the complicated contact pattern 34, the round spring 26 and the star spring 36. can do.

  In this embodiment, if one corner of the substrate body 12 is a corner portion 12b, the corner portion 12b is not fixed to the circuit board or the like of the device by soldering, so that the ground through hole is sandwiched between the corner portions 12b. The portion 12d and the through hole portion 12c are arranged to increase the fixing strength near the corner portion 12b.

  The present invention relates to a small-sized switch such as a surface mount tact switch. In addition, the present invention can be applied to a product that requires countermeasures against static electricity, such as a semiconductor element or a circuit on which it is mounted. It is.

It is principal part sectional drawing of the small switch which concerns on one Example of this invention. It is a surface side perspective view of the small switch shown in FIG. It is a back surface side perspective view of the small switch shown in FIG. It is a top view of the small switch shown in FIG. It is a side view of the small switch shown in FIG. It is a bottom view of the small switch shown in FIG. It is a top view of the board | substrate which shows an example of a conductive pattern. It is a top view of a waterproof sheet. It is a top view of the board | substrate which shows another conductive pattern. It is a top view of the board | substrate which shows the state which has arrange | positioned the round spring on the electrically conductive pattern shown in FIG. It is a top view of the board | substrate which shows the state which has arrange | positioned the star-shaped spring on the conductive pattern shown in FIG. It is a perspective view which shows the earth structure in the conventional small switch.

Explanation of symbols

2 Mold case 4 Metal cover 4a Side wall part 4b Ground part 10 Substrate 12 Substrate body 12a, 12c Through hole part 12b Corner part 12d Ground through hole part 14 Conductive pattern 14a Center fixed contact pattern 14b Peripheral fixed contact pattern 14c Through hole pattern 14d Ground pattern 14e Ground through hole pattern 16 Contact spring 18 Waterproof sheet 18a Conductive hole 20 Spacer 22 Conductive layer 24 Ground terminal 26 Round spring 36 Star spring

Claims (5)

A waterproof sheet covering the upper surface, and a substrate having external connection terminals,
A conductive layer is provided on the waterproof sheet and in a conduction hole provided in the waterproof sheet, the conductive layer is conducted to the ground pattern on the substrate through the conduction hole, and the ground pattern is provided on the substrate. A small switch characterized in that a ground terminal is formed by connecting to a through-hole pattern for grounding.   The small switch according to claim 1, wherein the conductive layer is formed by printing a conductive resin.   The small switch according to claim 2, wherein the conductive layer in the conduction hole of the substrate is formed by the conductive resin printed on the waterproof sheet flowing into the conduction hole.   The small switch according to claim 1, wherein the substrate has a corner portion at a position corresponding to the conduction hole, and the grounding pattern is formed on the corner portion.   5. The substrate has a ground through-hole portion and a through-hole portion at a position sandwiching the corner portion, and the ground through-hole pattern is formed in the ground through-hole portion. Small switch as described.

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