JP6704321B2 - Push-button switch - Google Patents

Description

The present invention relates to a push button switch used in a mobile terminal device such as a mobile phone or a small game machine.

BACKGROUND ART Push button switches are well known as operation switches used in mobile terminal devices and the like. The push button switch is mounted on the circuit board by soldering the end portion of the lead frame exposed from the housing of the push button switch to the metal wiring portion of the circuit board. For the base that constitutes the housing of the push button switch, insert the lead frame, which is a metal plate, into the mold, inject the molten resin around this lead frame, and integrally mold the lead frame and resin base material. It was produced by insert molding (Patent Document 1).

When insert-molding a base having a lead frame that is not a flat plate, the lead frame is pressed against the mold by pins so that the lead frame does not float in the mold. Therefore, when the base for the push button switch is manufactured by insert molding, the hole for the pin remains in the resin base material. Furthermore, when a base for a push button switch is manufactured by insert molding, a gap is created at the boundary between the resin base material and the lead frame. Therefore, when the push button switch is mounted on the circuit board by soldering, the flux flows in from the periphery of this hole or from this gap and covers the contact portion between the switch spring and the lead frame, and the switch electrical May cause poor contact.

If a base for a push button switch is manufactured by the 3D-MID (Three Dimensional Molded Interconnect Device) method, the base of the push button switch is not left on the resin base material, and the resin base material and the metal wiring There is no gap at the boundary. However, since the inside of the case of the push button switch using the base made by the 3D-MID method is airtight, when the push button switch is mounted on the circuit board by reflow soldering, the air inside the case expands. Then, the housing may be deformed.

JP, 2007-213880, A

The present invention has been made in view of the above circumstances, and provides a push button switch that suppresses the deformation of the housing and the inflow of flux into the conductor contact portion inside the housing during reflow soldering. The purpose is to

The push button switch of the present invention is formed on at least a part of the upper surface of the base material apart from the resin base material, the first plating layer formed on at least a part of the upper surface of the base material, and the first plating layer. A housing provided with a base having a second plated layer formed thereon and a lid provided above the base, and an inside of the housing insulated from the first plated layer and electrically connected to the second plated layer. And a movable conductor that comes into contact with the first plating layer at a contact point when it is pushed, and the base has an air passage for aerating the inside and the outside of the housing, and a midway portion of the air passage. , And a flux reservoir groove provided outside the contact point.

In the push button switch of the present invention, a recess may be provided in the center of the upper surface of the base material, and the movable conductor may be provided in the recess. In the push-button switch of the present invention, the base material has a high edge portion and a first low edge portion and a second low edge portion each having an upper surface lower than the upper surface of the high edge portion and higher than the bottom surface of the concave portion at the periphery of the upper surface. The first plating layer is provided on the upper surface of the first lower edge portion and the upper surface of the second lower edge portion so that a gap is formed between at least one of the first plating layer and the second plating layer and the high edge portion. It is preferable that the second plating layer is provided on each of the first and second surfaces, and the gap is at least a part of the ventilation path.

In the push button switch of the present invention, it is preferable that the flux collecting groove is provided in at least one of the first lower edge portion and the second lower edge portion. In the push button switch of the present invention, it is preferable that the gap is formed between the side surface of the high edge portion and at least one side surface of the first plating layer and the second plating layer. In the push button switch of the present invention, the width of the gap may be 20 to 100 μm. In the push button switch of the present invention, the base material may include a plurality of protrusions on the lower surface.

Since the push button switch of the present invention has the ventilation passage, it is possible to suppress the deformation of the housing due to the expansion of the internal air during the reflow soldering. Further, since the push button switch of the present invention is provided with the flux collecting groove on the outside of the conductor contact portion, it is possible to prevent the flux from reaching the conductor contact portion even if the flux flows into the housing during the reflow soldering. It can be suppressed.

The push button switch of 1st embodiment of this invention is shown, (a) is a perspective view from the upper part, (b) is a perspective view from the lower part. The exploded view of the push button switch of a first embodiment of the present invention. FIG. 3 is a central sectional view in the longitudinal direction of the push button switch according to the first embodiment of the present invention. The perspective view from the upper part of the base of the push button switch of a first embodiment of the present invention. The partial expanded sectional view of FIG. The push button switch of 2nd embodiment of this invention is shown, (a) is a perspective view from the upper part, (b) is a perspective view from the lower part. The exploded view of the push button switch of a second embodiment of the present invention. The exploded view of the push button switch of the modification of a second embodiment of the present invention.

Hereinafter, a push button switch of the present invention will be described based on embodiments with reference to the drawings. It should be noted that the drawings schematically show the push button switches and the members that constitute the push button switches, and the dimensions and dimensional ratios of these actual products do not necessarily match the dimensions and dimensional ratios in the drawings. Further, unless otherwise specified, in this specification, for convenience, directions such as “up” and “down” are expressed based on the orientation of the push button switch shown in FIG. In addition, when a numerical range is represented by using "-" between two numerical values, these two numerical values are also included in the range. In addition, duplicate description may be omitted as appropriate, and the same reference numerals may be given to the same members.

(First embodiment)
1A and 1B show a push button switch 10 according to a first embodiment of the present invention, FIG. 1A is a perspective view from above, and FIG. 1B is a perspective view from below. FIG. 2 is an exploded view of the push button switch 10. FIG. 3 is a cross-sectional view of the push button switch 10 taken vertically from the center of the upper surface thereof downward in the longitudinal direction. The push button switch 10 includes a housing 12, a tact spring 14 that is a movable conductor, and a button 16. The housing 12 includes a base 18 and a cover sheet 20 that is a lid.

FIG. 4 is a perspective view of the base 18 from above. FIG. 5 shows a portion surrounded by a dotted line in FIG. 4 together with a cross section when the base 18 is cut parallel to the side surface 22Sa of the base material 22. The base 18 includes a resin base material 22, a first plating layer 24, a second plating layer 26, a ventilation passage 30 for ventilating the inside and the outside of the housing 12, and an intermediate portion of the ventilation passage 30. , And a flux collecting groove 32 provided outside the electrical contact point of the switch. By providing the air passage 30 in the base 18, when the push button switch 10 is mounted on the circuit board by reflow soldering, the air expanded inside the housing 12 passes through the air passage 30 to the outside of the housing 12. Is discharged. Therefore, it is possible to substantially prevent the cover sheet 20 from being peeled off and the housing 12 from warping up due to the expanded air.

The base 18 is manufactured by, for example, the 3D-MID method. That is, the base material 22 is manufactured by injection molding of a thermoplastic resin, and the first plating layer 24 and the second plating layer 26 are formed on the surface of the base material 22 as follows. First, the surface of the base material 22 on which the first plating layer 24 and the second plating layer 26 are to be formed is irradiated with laser light. The portion of the base material 22 irradiated with the laser light is activated and metal nuclei are formed. Next, for example, the base material 22 is immersed in an electroless copper bath to deposit copper on the surface portion of the base material 22 irradiated with laser light. The wiring may be thickened by electrolytic copper plating. Then, the copper surface is plated with nickel, gold, or the like by flash plating processing.

As described above, since the conductor layer provided on the base 18 is not the lead frame integrated with the resin by insert molding but the plating layer, there is no gap between the conductor layer and the base material. Therefore, when the push button switch 10 is mounted on the circuit board by reflow soldering, flux does not flow into the housing 12 from between the conductor layer and the base material. Even if the flux flows from the air passage 30 into the housing 12, the flux that has flowed into the flux reservoir groove 32 provided outside the electrical contact point of the switch is accumulated in the air passage 30. Therefore, the flux does not reach the electrical contact point near the center inside the housing 12.

The first plating layer 24 is formed on at least a part of the upper surface 22U of the base material 22. The second plating layer 26 is formed on at least a part of the upper surface 22U of the base material 22 so as to be separated from the first plating layer 24, that is, to be insulated from the first plating layer 24. In the present embodiment, the first plating layer 24 and the second plating layer 26 are also formed on part of the side surfaces 22Sa, 22Sb of the base material 22 and part of the lower surface 22L.

A recess 22R is provided in the center of the upper surface 22U of the base material 22. By providing the recess 22R in the base material 22, the tact spring 14 can be housed in the recess 22R, and the push button switch 10 can be made thin. By providing the concave portion 22R in the base material 22, when flux flows from the ventilation passage 30 into the inside of the housing 12, the flux easily flows into the concave portion 22R lower than the surroundings. Since the flux collects in the flux collecting groove 32 provided outside the electrical contact point of the switch, the flux does not reach the electrical contact point near the center of the recess 22R.

The first plating layer 24 and the second plating layer 26 are also formed on the bottom 22RB of the recess 22R. However, the bottom 22RB of the recess 22R has two steps, and the first plating layer 24 is formed on the upper surface 22RBa of the lower step and the second plating layer 26 is formed on the upper surface 22RBb of the higher step. A high edge portion 22UEa, a first low edge portion 22UEb, and a second low edge portion 22UEc are formed on a peripheral edge 22UE of the upper surface 22U of the base material 22. The upper surfaces of the first low edge portion 22UEb and the second low edge portion 22UEc are higher than the bottom surface of the recess 22R, that is, the lower step upper surface 22RBa of the bottom 22RB of the recess 22R.

The first plating layer 24 is also formed on the upper surface of the first lower edge portion 22UEb. The second plating layer 26 is also formed on the upper surface of the second lower edge portion 22UEc. Then, a gap is formed between at least one of the first plating layer 24 and the second plating layer 26 and the high edge portion 22UEa. In the present embodiment, a gap is formed between both the first plating layer 24 and the second plating layer 26 and the high edge portion 22UEa. This gap is also a gap between the side surface of the high edge portion 22UEa and the side surface of the first plating layer 24, and a gap between the side surface of the high edge portion 22UEa and the side surface of the second plating layer 26. The gap has a width of 20 to 100 μm and is at least a part of the ventilation path 30 that vents the inside and the outside of the housing 12. In the present embodiment, since the conductor layer provided on the base material 22 is the plating layer, such a gap having a minute width is provided between the high edge portion 22UEa and the first plating layer 24 and the second plating layer 26. It is provided.

The flux pool groove 32 is provided in at least one of the first lower edge portion 22UEb and the second lower edge portion 22UEc. In the present embodiment, two flux collecting grooves 32 are provided on both the first low edge portion 22UEb and the second low edge portion 22UEc. Since the flux collecting groove 32 is provided in the first lower edge portion 22UEb and the second lower edge portion 22UEc, the flux flowing into the inside of the housing 12 is introduced into the flux collecting groove 32. In addition, since the opening of the flux pool groove 32 is higher than the bottom surface of the recess 22R and has the same height as the upper surfaces of the first low edge portion 22UEb and the second low edge portion 22UEc, the flux flowing into the housing 12 is The bottom of the flux recess 22R hardly reaches the bottom.

As shown in FIGS. 2 and 5, the air passage 30 extends from the opening of the side surface 22Sa of the base material 22, the side surface of the high edge portion 22UEa, the side surface of the first plating layer 24, the lower surface of the adhesive sheet 34, and the first low surface. After passing through the space surrounded by the upper surface of the edge portion 22UEb, the flux collecting groove 32 joins, the side surface of the high edge portion 22UEa, the side surface of the first plating layer 24, the lower surface of the adhesive sheet 34, and the first low edge portion 22UEb. It further connects to the recess 22R through a space surrounded by the upper surface.

The tact spring 14 is a thin metal plate having a dome shape. In this embodiment, three tact springs 14 are used in a stacked manner. The tact spring 14 is provided in the recess 22R inside the housing 12. Specifically, both ends of the tact spring 14 are placed on the upper surface 22RBb of the higher step of the bottom 22RB of the recess 22R. At this time, the one end 14a of the tact spring 14 is placed apart from the first plating layer 24 formed on the lower surface 22RBa of the bottom 22RB of the recess 22R, that is, so as to be insulated from the first plating layer 24. On the other hand, the other end 14b of the tact spring 14 is placed so as to come into contact with the upper surface of the second plating layer 26 formed on the upper surface 22RBb of the higher step of the bottom 22RB of the recess 22R, that is, so as to be conductive with the second plating layer 26. It has been.

When the central portion of the tact spring 14 is pushed from above, the central portion of the tact spring 14 is dented and comes into contact with the circular portion 24C of the first plating layer 24 at the contact point. At this time, the first plating layer 24 and the second plating layer 26 are electrically connected via the tact spring 14. In this embodiment, when the portion of the cover sheet 20 covering the button 16 is pressed with a finger, the tact spring 14 is pressed via the button 16. The tact spring 14 may be directly covered with the cover sheet 20 without providing the button 16.

On the other hand, when the central portion of the tact spring 14 is not pushed from above, for example, when the finger pushing the cover sheet 20 is released from the cover sheet 20, the tact spring 14 restores to the dome shape and becomes the first plating layer 24. The second plating layer 26 is insulated. In this way, when the first plating layer 24 and the second plating layer 26 are switched from the insulating state to the conducting state, it is recognized that the push button switch 10 has been pressed, and the circuit board operates. That is, the CPU on the circuit board executes a predetermined program in response to the push button switch 10 being pressed. The material, shape, thickness, quantity, etc. of the tact spring 14 are not particularly limited as long as the tact spring 14 functions as a movable member. The cover sheet 20 is made of an insulating material such as resin or rubber. The cover sheet 20 is bonded above the base 18 via the adhesive sheet 34.

The push button switch 10 is mounted on the circuit board by soldering to the metal wiring portion of the circuit board. That is, a circuit board in which a solder paste containing solder powder and flux is printed on a predetermined portion of a metal wiring is prepared, and the push button switch 10 is placed on the solder paste. Then, after heating the circuit board to melt the solder powder, the circuit board is cooled and the push button switch 10 is mounted on the circuit board. In this heating step, when the temperature of the push button switch 10 reaches, for example, about 80° C., the air inside the housing 12 is discharged to the outside via the ventilation path 30 (see the broken line arrow in FIG. 5 ). When the push button switch 10 reaches a temperature of, for example, about 150° C. in the cooling process after heating to a higher temperature, the flux may flow from the ventilation passage 30 into the inside of the housing 12. Since the flux that has flowed into the pool is accumulated, the flux does not reach the recess 22R.

(Second embodiment)
6A and 6B show a push button switch 40 according to a second embodiment of the present invention, FIG. 6A is a perspective view from above, and FIG. 6B is a perspective view from below. FIG. 7 is an exploded view of the push button switch 40. Unlike the base material 22 of the push button switch 10 of the first embodiment, the base material 42 of the push button switch 40 of the present embodiment has two protrusions 44, 44 on the lower surface 42L. The other constituent members of the push button switch 40 are the same as those of the push button switch 10. In this way, since the plurality of protrusions are provided on the bottom surface of the push button switch 40, the push button switch 40 can be mounted on the circuit board with high positional accuracy. Then, similar to the push button switch 10, during the reflow soldering, the flux hardly flows into the contact point between the tact spring 14 and the first plating layer 24.

FIG. 8 is an exploded view of the push button switch 50 of the application example of the second embodiment. No recess for accommodating the tact spring 14 is provided on the upper surface of the base material 52 of the push button switch 50. Therefore, between the base 54 and the cover sheet 20, an intermediate sheet 56 having a hole for accommodating the tact spring 14 in the center is provided. The base 54 and the intermediate sheet 56 are bonded via an adhesive layer provided on the lower surface of the intermediate sheet 56, and the intermediate sheet 56 and the cover sheet 20 are bonded via an adhesive layer provided on the upper surface of the intermediate sheet 56. Has been done. The base 54, the intermediate sheet 56, and the cover sheet 20 form a housing 58. In addition, in the push button switch 40, when the number of the tact springs 14 is increased, an intermediate sheet 56 may be provided between the cover sheet 20 and the base 46.

10 push button switch 12 housing 14 tact spring 14a one end 14b other end 16 button 18 base 20 cover sheet 22 base material 22U upper surface 22UE peripheral edge 22UEa high edge portion 22UEb first low edge portion 22UEc second low edge portion 22Sa, 22Sb side surface 22L Lower surface 22R Recessed portion 22RB Bottom 22RBa Lower step upper surface 22RBb Higher step upper surface 24 First plating layer 24C Circular portion 26 Second plating layer 30 Vent passage 32 Flux collecting groove 34 Adhesive sheet 40 Push button switch 42 Base material 42L Lower surface 44 Protrusion 46 Base 50 Push button switch 52 Base 54 Base 56 Intermediate sheet 58 Housing

Claims (7)

A resin base material, a first plating layer formed on at least a part of the upper surface of the base material, and a second plating formed on at least a part of the upper surface of the base material, apart from the first plating layer. A housing including a base including layers, and a lid provided above the base,
A movable conductor that is insulated from the first plating layer, is provided inside the housing so as to be electrically connected to the second plating layer, and contacts the first plating layer at a contact point when pressed,
A push button switch having
A push button switch in which the base includes an air passage for ventilating the inside and the outside of the housing, and a flux collecting groove provided outside the contact point in the middle of the air passage. In claim 1,
A recess is provided in the center of the upper surface of the base material,
A push button switch in which the movable conductor is provided in the recess. In claim 2,
The base material, on the periphery of the upper surface, a high edge portion, a first lower edge portion and a second lower edge portion that are lower than the upper surface of the high edge portion and have an upper surface that is higher than the bottom surface of the recessed portion,
At least one of the first plating layer and the second plating layer, the first plating layer on the upper surface of the first low edge portion, the second low The second plating layer is provided on the upper surface of the edge portion,
A push button switch in which the gap is at least a part of the ventilation path. In claim 3,
A push button switch in which the flux collecting groove is provided in at least one of the first lower edge portion and the second lower edge portion. In Claim 3 or 4,
A push button switch in which the gap is formed between a side surface of the high edge portion and at least one side surface of the first plating layer and the second plating layer. In claim 5,
A push button switch in which the width of the gap is 20 to 100 μm. In any one of Claim 1 to 6,
A push button switch in which the substrate has a plurality of protrusions on its lower surface.

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