JP5601646B2 - Conductive member for pushbutton switch and manufacturing method thereof - Google Patents

Description

  The present invention relates to a push button switch of an electronic device. More specifically, the present invention relates to a conductive member used for a push button switch of an electronic device.

  Conventionally, in order to reduce the resistance value of the conductive member used for the movable contact portion of the pushbutton switch, carbon such as acetylene black and carbon nanoparticles is added to the silicone rubber as a conductive filler (for example, see Patent Document 1). A method has been adopted in which a metal powder such as silver powder or nickel powder is contained in the silicone rubber material (see, for example, Patent Document 2).

  Furthermore, what stuck the metal plate and silicone is known (for example, refer patent document 3), The method (for example, refer patent document 4) which provides many holes in a metal plate and reduces the rigidity of a metal plate ) And a method using a wire mesh metal wire (for example, see Patent Document 5).

JP 2005-251515 A Japanese Patent Laid-Open No. 5-151853 JP-A 63-96822 International Publication No. 03/028054 Pamphlet JP 2004-342539 A

  However, as disclosed in Patent Document 1, a material obtained by adding carbon as a conductive filler to silicone rubber has a high resistance value, and if a high current is applied, the contact burns due to heat generation. There is a problem that cannot be used.

  In addition, the silicone rubber material disclosed in Patent Document 2 containing metal powder exhibits low resistance in the initial stage, but there is a gap between the metal powders as it is used. The resistance value increases, or because an insulator is sandwiched between metals, sparks occur between metal and metal during use of electricity, causing damage to contacts and substrates. There's a problem.

  In addition, the metal plate and the silicone rubber that are bonded to each other as disclosed in Patent Document 3 exhibit good low resistance due to the metal, but an insulating foreign substance has entered between the contact and the counter substrate electrode. In this case, there is a problem that the contact between the contact and the electrode cannot be obtained due to the high rigidity of the metal, and the contact cannot be turned on.

  If a metal plate having a large number of holes as disclosed in Patent Document 4 is used, this rigidity can be reduced. However, in order to produce holes, a punch method or an edging method is adopted. This requires a great deal of cost and lead time. In addition, there is a limit to the reduction in the rigidity of the metal due to the formation of holes, and there is a problem that it does not reach the ones added with carbon or metal powder as described in Patent Documents 1 and 2 with respect to foreign matter resistance.

  In the method using a wire net-like metal wire as disclosed in Patent Document 5, a process such as laminating a thin film material a plurality of times is required to prevent warping at the time of molding, and productivity is lacking. There's a problem.

  Accordingly, the present invention has been made in view of the above problems, and has a low contact resistance value that is stable even against repeated ON / OFF operations, and has excellent foreign matter resistance, and a method for manufacturing the same. Is intended to be provided at low cost.

  Such an object is achieved by the present inventions (1) to (10) below.

(1) A pushbutton switch conductive member made of a wire mesh and silicone rubber,
The conductive member for the pushbutton switch has a laminated structure of a wire mesh exposed portion / wire mesh embedded silicone rubber layer / silicone rubber layer, and the thickness of the wire mesh exposed portion is equal to or less than the thickness of the wire mesh embedded silicone rubber layer. A conductive member for a push button switch.

  (2) The silicone rubber layer includes 0.5 to 3 parts by mass of a silane coupling agent and 0.5 to 3 parts by mass of an adhesion assistant with respect to 100 parts by mass of silicone rubber. The conductive member for pushbutton switches as described.

  (3) The wire mesh is made of copper, copper-based alloy, brass or nickel wire having a diameter of 0.035 to 0.11 mm, and has a mesh density of 100 to 300 mesh (1) or (2) The conductive member for pushbutton switches as described.

  (4) The conductive member for a pushbutton switch according to (3), wherein the wire mesh is made of a brass wire.

  (5) The conductive member for a pushbutton switch according to any one of (1) to (4), wherein the exposed part of the wire mesh is plated.

  (6) A first laminate comprising a release resin film, a wire mesh, a silicone rubber layer, and a release resin film, wherein a release resin film, a silicone rubber film, a wire mesh, and a release resin film are sequentially laminated. A forming step, a step of putting the first laminate into a mold cavity and heating and pressurizing, and a release resin film obtained by taking out the first laminate from the die and laminating the first laminate on both surfaces. And forming a second laminated body having a laminated structure of a wire mesh exposed portion / wire mesh embedded silicone rubber layer / silicone rubber layer, and a step of punching the second laminated body to a predetermined size. In the laminate, the first laminate is heated and pressed so that the thickness of the exposed portion of the wire mesh is equal to or less than the thickness of the silicone rubber embedded silicone rubber layer.

  (7) The silicone rubber layer includes 0.5 to 3 parts by mass of a silane coupling agent and 0.5 to 3 parts by mass of an adhesion assistant with respect to 100 parts by mass of silicone rubber. The manufacturing method of the electrically-conductive member for pushbutton switches of description.

  (8) The wire mesh is made of copper, copper alloy, brass or nickel wire having a diameter of 0.035 to 0.11 mm, and the mesh density is 100 to 300 mesh (6) or (7) The manufacturing method of the electrically-conductive member for pushbutton switches of description.

  (9) The method for manufacturing a conductive member for a pushbutton switch according to (8), wherein the wire mesh is made of a brass wire.

  (10) The method for manufacturing a conductive member for a pushbutton switch according to any one of (7) to (9), further including a step of performing gold plating on the wire mesh exposed portion of the second laminate.

  ADVANTAGE OF THE INVENTION According to this invention, the electrically conductive member for pushbutton switches which has the stable low contact resistance value also to repeated ON / OFF operation | movement, and was excellent in the foreign material resistance, and its manufacturing method can be provided at low cost.

It is sectional drawing which shows schematic structure of the pushbutton switch which concerns on embodiment of this invention. It is typical sectional drawing of the 2nd laminated body which shows the structure of the electrically-conductive member for pushbutton switches which concerns on embodiment of this invention. It is a flowchart which shows the manufacturing process of the electrically-conductive member for pushbutton switches which concerns on embodiment of this invention. It is a typical sectional view of the 1st layered product concerning the embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view illustrating a state in which a pushbutton switch conductive member according to an embodiment of the present invention is provided at a movable contact portion of a pushbutton switch. FIG. 2 is a schematic cross-sectional view of a second laminated body showing a laminated state of a wire mesh and silicone rubber (SR) of the conductive member for a pushbutton switch according to the embodiment of the present invention. FIG. 3 is a flowchart showing a manufacturing process of the pushbutton switch conductive member according to the embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of a first laminate in which a peeling resin film is bonded to both surfaces according to an embodiment of the present invention.

  The conductive member 3 made of the second laminated body 31 having the wire mesh exposed portion 311 is placed on the movable contact portion 2 of the pushbutton switch 1 that contacts the fixed contact 5 on the substrate 4, and the wire mesh exposed portion 311 faces downward in FIG. It is provided as follows.

  The conductive member 3 made of silicone rubber (SR) and a wire mesh is manufactured by punching from the second laminate 31 shown in FIG. SR may be insulative or conductive, but a metal adhesive is used. In the second laminate 31, a wire mesh exposed portion 311 is formed so that 1/2 or less of the thickness of the wire mesh is exposed on one side, and the remaining portion exceeding 1/2 of the thickness of the wire mesh is the metal adhesive SR. It is physically fitted inside and chemically bonded to the SR, and the wire mesh-SR is firmly joined to form the wire mesh embedded SR layer 312. If the wire mesh exposed portion 311 is exposed beyond 1/2 of the thickness of the wire mesh, a problem arises in durability when the pushbutton switch 1 is repeatedly turned ON / OFF many times. The SR layer 313 is composed only of SR.

  When a metal mesh is used for the conductive member 3, (a) a metal is used as the conductive filler, so that low resistance can be developed. (B) a metal mesh connected to the metal is used as the conductive filler, so it is used like a metal powder. The contact between metal powders is not lost and the resistance value does not increase. (C) Conductive filler made of metal wire provides flexibility and resistance to foreign matters There is an advantage that the conductivity is ensured by avoiding foreign matters by deformation.

  Here, examples of the wire mesh material include stainless steel, nickel, copper, phosphor bronze, brass, and the like, but brass is preferable in terms of cost. The wire diameter of the metal wire used for the wire mesh is preferably 0.035 to 0.11 mm, more preferably 0.040 to 0.090 mm. The mesh density in this case is preferably 100 to 300 mesh (the number of meshes between 25.4 mm is 100 to 300), more preferably 120 to 250 mesh. If the wire diameter of the metal wire is less than 0.035 mm, there is a possibility of disconnection due to an insulating foreign material, so that it is not preferable. Cause problems. When the mesh density exceeds 300 mesh, the rigidity of the wire mesh is too small, and therefore, the conductive member 3 warps due to the shrinkage of the silicone rubber when it is attached to the movable contact portion 2, which is not appropriate. Those having a mesh density of less than 100 mesh are too coarse as conductive members.

  As the structure of the wire mesh, a plain woven wire mesh is easily available and inexpensive, and the performance as a contact point is sufficient and suitable. However, other knitting methods may be used, and a sintering process may be performed.

  In consideration of the environmental resistance against the surface oxidation of the wire mesh, it is effective to apply gold plating to the wire mesh exposed portion 311.

  Moreover, as metal-adhesive SR material, with respect to 100 mass parts of silicone rubbers (for example, Shin-Etsu Chemical Co., Ltd. product, KE-961U), cross-linking agent C-25A (Shin-Etsu Chemical Co., Ltd.) 0. 5-3 parts by mass, cross-linking agent C-25B (manufactured by Shin-Etsu Chemical Co., Ltd.) 2.0 parts by mass, silane coupling agent (for example, Shin-Etsu Chemical Co., Ltd., KBM-403) 0.5-3 mass It is effective to use a mixture of 0.5 to 3 parts by mass of a part and an adhesion assistant (for example, X-93-3046 manufactured by Shin-Etsu Chemical Co., Ltd.).

  In the metal-adhesive SR composed of such components, by adding an adhesion assistant that is incompatible with silicone rubber, the adhesion assistant silane coupling agent can be efficiently used by using the adhesion assistant as a solvent. It can ooze out to the adhesive interface.

  In addition, both the silane coupling agent and the adhesion assistant develop an adhesive force to the SR and the metal mesh, but the silane coupling agent is strongly attracted to the metal side by the polarity and is effective for adhesion to the metal mesh. Since the adhesion assistant has a Si—H group in the structure, it works relatively strongly toward the SR side and is effective for adhesion to the SR. As a result of these synergistic effects, a strong adhesive force between the SR and the wire net is obtained as a result.

  Hereinafter, the manufacturing method of the conductive member for a pushbutton switch according to the embodiment of the present invention will be described with reference to the manufacturing process flowchart shown in FIG.

  First, a wire mesh, a metal adhesive silicone rubber (SR), and two release resin films are prepared and bonded together, and the release resin film / wire mesh / SR layer / removal shown in FIG. A first laminated body 32 having a predetermined size made of a resin film is formed (S101).

  The first laminated body 32 is put into a mold having a cavity with a predetermined dimension (S102), and is heated and pressed (S103).

  By heating and pressing, the wire mesh is pushed into the SR layer 322 and physically fitted, and the wire mesh and SR are integrated, but after the heat and pressure forming, 1/2 or less of the thickness of the wire mesh is exposed. Therefore, the thickness of the mold cavity and the heating and pressing molding conditions are set.

  When the heat and pressure molding is completed, the first laminated body 32 is taken out (S104), the peeling resin films 323a and 323b on both surfaces of the first laminated body 32 are peeled off, and the wire mesh exposed portion / wire mesh embedded silicone shown in FIG. The second laminated body 31 having a laminated structure of rubber layer / silicone rubber layer is taken out (S105).

  The second laminated body 31 is punched out to a predetermined dimension to form the conductive member 3 of the pushbutton switch 1 (S106).

  In the manufacturing process flow chart shown in FIG. 3, there is no process of bonding the metal mesh and SR using an adhesive, and the adhesion between the metal mesh and SR is the physical property of the metal mesh to the SR in the heat-press molding of the mold. The manufacturing cost is reduced because it is made by chemical bonding by mechanical fitting and SR of metal adhesion.

(Example)
A mold having a cavity having a length of 120 mm, a width of 70 mm, and a depth of 0.55 mm was used. In Examples 1 to 6, a metal mesh (sold by Kukara Co., Ltd.) made of different metals was cut into a length of 70 mm and a width of 50 mm, and a polyethylene terephthalate (PET) sheet having a thickness of 0.055 mm as a release resin film was obtained. Two sheets and a silicone rubber (SR) sheet are cut into a length of 90 mm and a width of 50 mm, and these are bonded together to form a first laminate 32 made of PET film / metal mesh / SR layer / PET film, and mold Into the cavity.

  The thickness of the SR sheet is such that the thickness of the wire mesh exposed portion 311 in the second laminate 31 taken out in step S105 of FIG. 3 is equal to or less than the thickness of the wire mesh embedded silicone rubber layer 312. It was set appropriately according to.

The SR layer 322 in the first laminate 32 is obtained by adding a crosslinking agent C-25A and B (manufactured by Shin-Etsu Chemical Co., Ltd.) to C-25A in 100 parts by mass of silicone rubber compound KE-961U (manufactured by Shin-Etsu Chemical Co., Ltd.). 0.5 parts by weight of the material, 2.0 parts by weight of the C-25B material, 1 part by weight of the silane coupling material KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.) and an epoxy-based adhesive aid X-93-3046 (Shin-Etsu Chemical ( (Made by Co., Ltd.) 1 part by mass was added and kneaded and dispensed to a predetermined size on a PET film. The above-mentioned materials are laminated in the order of PET film / metal mesh / SR / PET film to form a first laminate 32, which is put into a mold cavity and heated and pressed under conditions of 20.0 MPa at 125 ° C. for 4 minutes. Thus, a second laminated body 31 of an integrated sheet of SR and a wire mesh projecting 1/2 or less of the thickness of the wire mesh on one side was produced. The conductive member 3 was produced by punching the integrated sheet with a punching die adjusted so as to be punched to a diameter of φ3, and a push button switch was produced using the conductive member 3 and tested.

Example 1
A plain weave wire mesh having a thickness of 0.17 mm and 120 mesh using a brass wire having a diameter of 0.09 mm was used. An SR sheet having a thickness of 0.355 mm was used.

(Example 2)
A 200 mesh 3D wire mesh using a 0.04 mm diameter stainless steel wire was used.

(Example 3)
A 150 mesh sintered wire mesh using a 0.06 mm diameter stainless steel wire was used.

Example 4
A 200 mesh plain woven wire mesh using copper wire with a diameter of 0.05 mm was used.

(Example 5)
A 120 mesh twill wire mesh using an aluminum wire with a diameter of 0.10 mm was used.

(Example 6)
A 150 mesh plain woven wire mesh using nickel wire with a diameter of 0.065 mm was used.

(Comparative example)
A mold capable of forming a rubber sheet having a length of 115 mm, a width of 65 mm, and a depth of 0.5 mm and the following materials were prepared.
Metal sheet: Primer No. on the Ni-plated surface side of Ni-plated 50 μm white with double-sided Ni plating and Au plating on one side. 18 (Shin-Etsu Chemical Co., Ltd.) was applied and heat-treated with a dryer at 200 ° C. for 1 hour was prepared.
Dispensing rubber sheet: Silicone rubber compound KE-961U (Shin-Etsu Chemical Co., Ltd.) 100 parts by mass and 2.0 parts by mass of cross-linking agent C-8 (Shin-Etsu Chemical Co., Ltd.) were kneaded on a 50 μm PET. Into 0.5 mm thickness.
The metal sheet primer and coated surface are placed on a silicone rubber sheet and placed in a mold, heated and pressed at 165 ° C. for 5 minutes to obtain a sheet of 0.5 mm thickness, one side is metal and the other side is silicone rubber. Then, this was punched out with a punching die adjusted so as to be punched to a diameter of 3 mm to produce a contact member, and further, a push button switch was produced and tested using this contact member.

(Characteristic test)
The results of a characteristic test on the pushbutton switch 1 having the configuration shown in FIG. 1 manufactured in Examples 1 to 6 and Comparative Example will be described below.

  As the substrate 4 of the push button switch 1, a comb-tooth type gold plating substrate having an electrode width of 0.5 mm, an electrode interval of 0.5 mm, and an electrode of copper foil 35 μm + Ni plating 3 μm + Au plating 0.3 μm was used.

(Contact resistance value)
The contact resistance value was measured using the pushbutton switch produced in Examples 1-6 and the comparative example. Measurement is ADVANTEST R6561 with a load of 4.9 N as a measuring instrument.
DIGITAL MULTITIMER was used.
Table 1 shows the measurement results of the contact resistance value. The criterion is 2Ω or less.

  From Table 1, it was found that good contact resistance values were obtained in Examples 1, 3, and 6.

(Electric keying test)
An energization keying test was performed using the pushbutton switches produced in Examples 1 to 3 and 6 and the comparative example, and a voltage drop was measured when 100 mA was applied with an applied voltage of 13.5V. The voltage drop was measured with a load of 4.9 N, 2 seconds / cycle (ON 1 second / OFF 1 second), and ADVANTEST R6551 as a measuring instrument.
Using DIGITAL MULTITIMER, the number of keystrokes was up to 300,000.
Table 2 shows the measurement results of the voltage drop (V). The criterion is 1V or less.

  From Table 2, it was found that in Examples 1 and 6, the voltage drop was small with respect to the number of keystrokes up to 300,000.

(Keystroke durability test)
Using the pushbutton switches produced in Examples 1 and 3 and the comparative example, a keystroke durability test was performed to measure a contact resistance value. The contact resistance value is measured with a load of 4.9 N, 2 seconds / cycle (ON 1 second / OFF 1 second), and ADVANTEST R6551 as a measuring instrument.
Using DIGITAL MULTITIMER, the number of keystrokes was up to 300,000.
Table 3 shows the measurement results of the contact resistance value (Ω).

  From Table 3, it was found that Example 1 showed good keystroke durability with respect to the number of keystrokes up to 300,000.

(Environmental testing)
An environmental test was performed using the pushbutton switches produced in Examples 1 and 6 and the comparative example, and the contact resistance values before and after the test were measured. The contact resistance value is measured with a load of 4.9 N and ADVANTEST R6551 as a measuring instrument.
This was done using a DIGITAL MULTITIMER. There were three environmental conditions: high temperature and high humidity (65 ° C. and 95% RH 240H), high temperature (85 ° C. and 240 H), and hydrogen sulfide resistance (3 ppm H ₂ S, 40 ° C. and 80% RH 240H).
Table 4 shows the measurement results of the contact resistance value (Ω). The criterion is 2Ω or less.

  From Table 4, it was found that Examples 1 and 6 showed good environmental resistance.

(Foreign matter resistance test)
A foreign matter resistance test was performed using the pushbutton switch manufactured in Example 1 and the comparative example. The voltage drop when the current was applied 100 mA at an applied voltage of 13.5 V and the key was pressed up to 500 times was measured every initial, once, 100 times, 300 times, and 500 times. As foreign matters, up to 20 glass beads having a diameter of 100 μm of insulating foreign matter were randomly arranged on the fixed contacts 5. The voltage drop is measured with a load of 4.9 N, 1 cycle / second, and ADVANTEST R6143 as a measuring instrument.
This was done using a DIGITAL MULTITIMER.
Table 5 shows the measurement results of the foreign matter resistance test. In Table 2, “-” indicates “conduction failure” indicating a state in which no conduction occurs or the voltage drop value is unstable and cannot be read. Table 6 shows the detailed results of the foreign matter resistance test of Example 1, and Table 7 shows the detailed results of the foreign matter resistance test of the comparative example.

  From Tables 5 to 7, it was found that Example 1 was more excellent in foreign matter resistance than the Comparative Example.

From the results relating to the embodiments of the present invention, the following has become clear.
(A) The conductive member for a pushbutton switch manufactured by integrally molding with a metal-adhesive silicone rubber using a brass wire mesh is particularly resistant to foreign matters as compared to the conductive member for a pushbutton switch manufactured using a white sheet. Excellent in properties.
(B) A conductive member for a pushbutton switch manufactured by integrally molding with a metal-adhesive silicone rubber using a brass wire mesh satisfies all the required performance for a pushbutton switch and is excellent in cost.

  As mentioned above, although this invention was demonstrated using embodiment, it cannot be overemphasized that the technical scope of this invention is not limited to the range as described in the said embodiment. It is obvious that various modifications or improvements can be added to the above embodiment. In addition, embodiments with such changes or improvements are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Pushbutton switch 2 Movable contact part 3 Conductive member 4 Board | substrate 5 Fixed contact 31 2nd laminated body 311 Wire mesh exposure part 312 Wire mesh embedded SR layer 313 SR layer 32 1st laminated body 321 Wire mesh 322 SR layer 323a, 323b Release resin film

Claims (4)

A step of laminating a release resin film, a silicone rubber film, a wire mesh, and a release resin film in this order to form a first laminate composed of a release resin film / wire mesh / silicone rubber layer / release resin film. A and
A step B of performing heating in a state where the a process performed next the first laminate was pressurized and charged into the cavity of the mold of the step A,
In the step performed after the step B, the first laminated body is taken out from the mold, and the release resin film laminated on both surfaces from the first laminated body is peeled off, and a wire mesh exposed portion / a step C of forming a second laminate having a laminated structure of wire mesh embedded silicone rubber layer / the silicone rubber layer,
The process is performed after the process C, and the process D includes punching the second laminated body into a predetermined size.
In the step B, in the second laminate , heating is performed in a state where the first laminate is pressurized so that the thickness of the exposed portion of the wire mesh is equal to or less than the thickness of the silicone rubber embedded silicone rubber layer. And
The pushbutton switch characterized in that the silicone rubber film comprises 0.5 to 3 parts by mass of a silane coupling agent and 0.5 to 3 parts by mass of an adhesion assistant with respect to 100 parts by mass of the silicone rubber compound. For producing a conductive member. A step of laminating a release resin film, a silicone rubber film, a wire mesh, and a release resin film in this order to form a first laminate composed of a release resin film / wire mesh / silicone rubber layer / release resin film. E and
Step F performed after Step E, in which heating is performed in a state where the first laminate is put into a cavity of a mold and pressurized,
In the step performed after the step F, the first laminated body is taken out from the mold, and the peeling resin film laminated on both surfaces from the first laminated body is peeled off, and a wire mesh exposed portion / Forming a second laminate having a laminate structure of a wire mesh embedded silicone rubber layer / silicone rubber layer; and
A step H that is performed next to the step G, and a step H of performing gold plating on the wire mesh exposed portion of the second laminate;
The process is performed after the process H, and includes the process I for punching the second laminated body into a predetermined size.
In the step F, the first laminate is heated in the second laminate so that the thickness of the exposed portion of the wire mesh is equal to or less than the thickness of the silicone rubber embedded silicone rubber layer. And
The pushbutton switch characterized in that the silicone rubber film comprises 0.5 to 3 parts by mass of a silane coupling agent and 0.5 to 3 parts by mass of an adhesion assistant with respect to 100 parts by mass of the silicone rubber compound. For producing a conductive member. The wire mesh is copper Fai0.035～0.11Mm, copper-based alloys, made from the line of brass or nickel, a push button switch according to claim 1 or 2 mesh density is characterized by a 100 to 300 mesh For producing a conductive member. The method for manufacturing a conductive member for a pushbutton switch according to claim 3 , wherein the wire mesh is made of a brass wire.

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