Patent Grant
10763052
The present application is a National Phase of International Application Number PCT/JP2017/035767, filed Oct. 2, 2017, which claims the benefit of priority from Japanese Patent Application No. 2016-198822 filed on Oct. 7, 2016, the contents of which are incorporated herein by reference. Additionally, the contents described in the patents, patent applications and literatures cited in this patent application are also incorporated herein by reference.
The present invention relates to a contact member, a contact member production method, and a push-button switch member equipped with the contact member.
In relation to push-button switch members, as a contact member that can elastically move into contact with and move apart from a contact on a circuit board, there is conventionally known a contact member in which a thin metal plate or a plated metal plate is affixed to a silicone rubber. As contact members of other forms, there are also conventionally known a contact member in which holes are opened in a thin metal plate, a contact member in which a wire mesh is affixed to a silicone rubber, and a contact member in which the wire mesh is covered with a different type of metal (refer to Patent Literatures 1 to 4).
The contact members 50, 60 illustrated in
Patent Literature 1: Japanese Utility Model Laid-Open No. 62-054433
Patent Literature 2: Japanese Patent Laid-Open No. 2004-342539
Patent Literature 3: Japanese Patent Laid-Open No. 2012-185956
Patent Literature 4: Japanese Patent Laid-Open No. 2014-240058
However, the following are required on the conventionally known contact members and push-button switch members provided with these contact members. A first requirement is not only to realize a high corrosion resistance by reducing the exposure of the metal such as nickel, SUS or the like but also to enhance the reliability of a contact by preventing the contact member from malfunctioning while in use. A second requirement is to realize a low cost by preventing holes from being made when punching or etching is performed and reducing an amount of coating metal to be used.
An object of the present invention is to meet the above requirements, that is, to provide a highly reliable and low-cost contact member and a push-button switch member including the contact member.
The inventor has made every effort to achieve the object, as a result of which a contact member has been completed in which part of a meshed contact represented by a wire mesh is embedded in a rubber, and a highly conductive metal different in type from the meshed contact is coated on the meshed contact exposed from the rubber with a bonding interface between the rubber and the meshed contact left as it is. A specific solution of the present invention to the problem described above is as follows.
With a view to achieving the object, according to an embodiment, there is provided a contact member including a meshed contact including one or more layers of a metal other than a noble metal, the meshed contact being embedded in one surface of a rubber-like elastic body in such a manner as to be exposed, in which a highly conductive metal coat layer having a higher conductivity than that of the metal in an outermost surface of the meshed contact is provided only on a region of the meshed contact exposed from the rubber-like elastic body.
In a contact member according to another embodiment, the meshed contact may be a wire mesh comprising a plurality of metal wires intersecting each other, and the wire mesh may be embedded in the rubber-like elastic body with at least the metal wires in one direction of the metal wires making up the wire mesh exposed.
In a contact member according to a further embodiment, the wire mesh may be formed by interlacing the metal wires in two directions, the metal wires in the two directions may be embedded in the rubber-like elastic body with both the metal wires in the two directions exposed, and the metal wires in either of the two directions may be covered with the coat layer over a wider area than an area where the metal wires in the other of the two directions are covered with the coat layer in a plan view.
In a contact member according to another embodiment, the wire mesh may be formed by interlacing the metal wires in two directions, the metal wires in the two directions may be embedded in the rubber-like elastic body with both the metal wires in the two directions exposed, and a number of points where the metal wires in either of the two directions are exposed from the rubber-like elastic body may be greater than a number of points where the metal wires in the other of the two directions are exposed from the rubber-like elastic body.
In a contact member according to another embodiment, the wire mesh may be formed by interlacing the metal wires in two directions, the metal wires in the two directions may be embedded in the rubber-like elastic body with both the metal wires in the two directions exposed, and a height in which the metal wires are exposed from the rubber-like elastic body may be smaller than a diameter of the metal wires so exposed.
In a contact member according to a further embodiment, the coat layer may be an electrolytic plating layer.
In a contact member according to another embodiment, one or a plurality of projecting portions may be provided on a surface of a side of the rubber-like elastic body, the side being opposite to the side where the meshed contact is exposed.
In a contact member according to another embodiment, a surface of each of the projecting portions may be a curved surface.
With a view to achieving the object, according to an embodiment, there is provided a contact member production method for producing the contact member of any one of the contact members described above, including a meshed contact portion embedding step of embedding a meshed contact including one or more layers of a metal other than a noble metal in a curable rubber composition that is in a stage before a rubber-like elastic body is cured completely in such a manner that the meshed contact is exposed, a curing step of curing the curable rubber composition following the meshed contact portion embedding step, and a plating layer forming step of forming a highly conductive metal coat layer having a higher conductivity than that of the metal in an outermost surface of the meshed contact only on a region of the meshed contact exposed from the rubber-like elastic body.
With a view to achieving the object, according to an embodiment, there is provided a push-button switch member including any one of the contact members described above.
According to the present invention, it is possible to provide the highly reliable and low-cost contact member and the push-button switch member including the contact member.
Next, preferred embodiments of the present invention will be described by reference to drawings. Note that embodiments that will be described below do not limit inventions according to claims and that all elements and combinations thereof that will be described in the following embodiments are not necessarily essential to a solution to the problem of the present invention.
As illustrated in
When the key top 3 is not pressed down from above, the contact member 10 and the circuit board side contacts 7, 8 are held in a non-contact state. When the key top 3 continues to be pressed down from above and the pressure exceeds a certain threshold, the dome portion 4 drastically deforms (buckles), whereby the contact member 10 comes into contact with the circuit board side contacts 7, 8. A conductive path is formed from the circuit board side contact 7 to the circuit board side contact 8 by way of the contact member 10 by the contact of the contact member 10 with the circuit board side contacts 7, 8, whereby a switch is on (or off). When the pressure is released from the key top 3, the dome portion 4 restores its original shape by virtue of its own elastic force, whereby the key top 3 rises. As a result, the contact member 10 separates from the circuit board side contacts 7, 8.
In this embodiment, the push-button switch member 1 is formed into an integral unit from a rubber material. However, the push-button switch member 1 does not have to be formed into the integral unit from the rubber material, and hence, the push-button switch member 1 may be formed from any other material, provided that only at least the dome portion 4 is formed from a rubber material. Thermosetting elastomer such as silicone rubber, urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene-propylene-diene rubber, nitrile rubber (NBR), or styrene-butadiene rubber (SBR); thermoplastic elastomer such as urethane-based, ester-based, styrene-based, olefin-based, butadiene-based, or fluorine-based elastomer; or combinations thereof are preferably used as a rubber material from which the push-button switch member 1 is formed. Silicone rubber is particularly preferable among the candidates described above.
The contact member 10 illustrated in
In this embodiment, the meshed contact 12 is a wire mesh made up of a plurality of metal wires 22, 23 intersecting each other. The wire mesh is preferably formed by interlacing a plurality of metal wires 22, 23, and is embedded in the rubber-like elastic body 11 in such a manner that in the metal wires 22, 23 that make up the wire mesh, at least the metal wires 22 in one direction (and/or the metal wires 23) are exposed. Note that the meshed contact 12 is not limited to the wire mesh and hence may be a plate having a plurality of holes or an integral structure having a mesh-like form. The meshed contact 12 is preferably attached directly to the rubber-like elastic body 11 without involving an adhesive layer on the rubber-like elastic body 11. Involving no adhesive layer or the like can reduce a risk of separation of the meshed contact 12 from the rubber-like elastic body 11, thereby making it possible to enhance more the quality of the push-button switch member 1. Omitting a step of forming an adhesive layer can also reduce the production cost of the push-button switch member 1.
The meshed contact 12 is preferably made up of metal wires 22, 23 in two directions that intersect each other and is embedded in the rubber-like elastic body 11 in such a manner that in the metal wires 22, 23 in the two directions, at least the metal wires 22 (or 23) in one direction are exposed. More preferably, the meshed contact 12 is embedded in the rubber-like elastic body 11 in such a manner that both the metal wires 22, 23 in the two directions are exposed, and either of the metal wires 22, 23 or the metal wires 22 are covered with the plating layer 30 over a wider area than an area where the other of the metal wires 22, 23 or the metal wires 23 are covered with the plating layer 30.
The meshed contact 12 (that may be referred to as a wire mesh) is formed by interlacing the metal wires 22, 23 in the two directions and is embedded in the rubber-like elastic body 11 in such a manner that both the metal wires 22, 23 in the two directions are exposed. Then, a number of points where either of the metal wires 22, 23 or the metal wires 22 are exposed from the rubber-like elastic body 11 can be made greater than a number of points where the other of the metal wires 22, 23 or the metal wires 23 are exposed from the rubber-like elastic body 11. Additionally, a height in which the metal wires 22, 23 are exposed from the rubber-like elastic body 11 can be made smaller than a diameter of the exposed metal wires 22, 23. This will be described in detail below.
The meshed contact 12 is formed by interlacing pluralities of metal wires 22, 23. The metal wires 22, 23 may have the same diameters or different diameters. A wire mesh formed using plain weave, twill weave or plain Dutch weave can be raised as an example of a preferred meshed contact 12. When referred to in this application, “to intersect” is construed as including not only a positional relationship in which metal wires intersect at right angles but also a positional relationship in which metal wires intersect at any other angle than right angles.
As illustrated in
As the covering state advances from X5 towards X1, the meshed contact 12 moves further in the direction in which the meshed contact 12 is embedded into the rubber-like elastic body 11. As a result, a bonding force between the meshed contact 12 and the rubber-like elastic body 11 becomes stronger. However, the covering area by the plating layer 30 becomes smaller, whereby the function of the meshed contact 12 as an electric contact is reduced. On the contrary, as the covering state advances from X1 to X5, the meshed contact 12 moves further in a direction in which the meshed contact 12 is exposed on the rubber-like elastic body 11. As a result, the bonding force between the meshed contact 12 and the rubber-like elastic body 11 becomes weaker. However, the covering area by the plating layer 30 becomes greater, whereby the function of the meshed contact 12 as the electric contact is increased.
To enhance the bonding force between the meshed contact 12 and the rubber-like elastic body 11 and allow the meshed contact 12 to exhibit its high functionality as the electric contact, the meshed contact 12 is preferably embedded in the rubber-like elastic body 11 in such a manner as to produce a state where the plating layer 30 covers at least either of the metal wires 22 and the metal wires 23 and the covering areas of the metal wires 22 and the metal wires 23 differ from each other (the covering states X2 to X4). The meshed contact 12 is more preferably embedded in the rubber-like elastic body 11 in such a manner as to produce a state where the plating layer 30 covers both the metal wires 22 and the metal wires 23 and the covering areas of the metal wires 22 and the metal wires 23 differ from each other (the covering states X3 and X4).
When attempting to enhance the bonding force between the meshed contact 12 and the rubber-like elastic body 11 and allow the meshed contact 12 to exhibit its high functionality as the electric contact from a different point of view, a ratio of the number of apexes of the metal wires 22 where the metal wires 22 project from the rubber-like elastic body 11 to the number of apexes of the metal wires 23 where the metal wires 23 project from the rubber-like elastic body 11 can be raised. Assuming that of the metal wires 22 and the metal wires 23, one smaller number of apexes is referred to as P1, while the other number of apexes is referred to as P2, 100(%)×P1/P2 is preferably 10% or greater and 90% or smaller, is more preferably 20% or greater and 70% or smaller, and is much more preferably 30% or greater and 50% or smaller. With 100(%)×P1/P2 set to fall within these ranges, the bonding force can be ensured as a result of an increase in the bonding area between the rubber-like elastic body 11 and the metal wires 22, 23 and an increase in the fitting effect, and the reliability can be ensured by an increase in the number of covering portions by the plating layer 30 that are brought into contact with the circuit board side contacts 7, 8. In addition to theses, the extent of the plating layer 30 covering the projecting portions of the metal wires 22, 23 does not have to be increased excessively, thereby making it possible to realize a reduction in production costs.
In place of or in addition to the view points of the covering areas of the metal wires 22 and the metal wires 23 covered by the plating layer 30 and the numbers of exposed apexes of the metal wires 22 and the metal wires 23, the balance between the function to enhance the bonding force between the meshed contact 12 and the rubber-like elastic body 11 and the function to allow the meshed contact 12 to exhibit its high performance as the electric contact can be controlled based on exposed heights of the metal wires 22 and the metal wires 23 as below. As illustrated in
The metal wires 22, 23 should be formed of a conductive metal other than a noble metal whether the metal wires 22, 23 are formed of the same material or different materials. For example, the metal wires 22, 23 are preferably formed of any one of nickel (Ni), copper (Cu), tungsten (W), and stainless steel (SUS) or an alloy of any two or more metals selected from them. When referred to herein, the noble metal denotes one or some of gold (Au), platinum (Pt), silver (Ag), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru) or osmium (Os). The plating layer 30 is preferably formed of one or some of, for example, gold (Au), silver (Ag), nickel (Ni), palladium (Pd), tungsten (W), molybdenum (Mo), and copper (Cu) on the premise that the plating layer 30 is formed of a metal differing from the metal wires 22, 23 and a highly conductive metal having superior conductivity to that of the metal wires 22, 23. A preferred metal making up the plating layer 30 is a noble metal. In the case where electrolytic plating is used as a method of forming the plating layer 30, which will be described later, the metal forming the plating layer 30 needs to be ionized less than the metal making up the metal wires 22, 23. The plating layer 30 is preferably formed through electrolytic plating or electroless plating, and the plating layer 30 is more preferably formed through electrolytic plating. The electrolytic plating and the electroless plating will be described in detail later. A wire mesh formed by interlacing metal wires 22, 23 formed by applying a nickel layer around a copper core can be raised as a preferred example of the meshed contact 12. As an example of a form of the meshed contact 12, a plating layer 30 of gold is formed only on regions of the meshed contact 12 where the meshed contact 12 is exposed on the rubber-like elastic body 11.
In a contact member 10a according to the second embodiment, like reference signs will be given to like configurations to those of the contact member 10 according to the first embodiment, so that descriptions thereof will be omitted here based on the understanding that the descriptions are replaced by the similar descriptions made in the first embodiment.
In the contact member 10a according to the second embodiment, a meshed contact 12 is embedded deeper into a rubber-like elastic body 11 than in the first embodiment. Due to this, a plating layer 30 is coated only on metal wires 22 making up the meshed contact 12. In a cross-sectional view taken along a line B-B in
In a contact member 10b according to the third embodiment, like reference signs will be given to like configurations to those of the contact members 10, 10a of the first and second embodiments, so that descriptions thereof will be omitted here based on the understanding that the descriptions are replaced by the similar descriptions made in the first and second embodiments.
The contact member 10b according to the third embodiment is like to the contact member 10 according to the first embodiment except that a plurality of projecting portions 40 are provided on a side of a rubber-like elastic body 11 opposite to a side where a meshed contact 12 is formed. In a cross-sectional view taken along a line C-C in
In addition, the state of the surface of the contact member 10b where the projecting portions 40 are formed can be differentiated from the state of the surface thereof where the meshed contact 12 is formed, and hence, in disposing the contact member 10b in an interior of a forming mold, it is possible to reduce a risk of the contact member 10b being disposed in the interior of the forming mold with an opposite surface to a proper layered surface thereof erroneously oriented upwards.
Forming the projecting portions 40 enhances the reliability of the push-button switch member 1 including the contact member 10b and contributes to a reduction in production cost due to the following reason. As another method for preventing the affixation of the contact members 10b, a method is also considered in which ultraviolet ray is shone onto a surface of a contact member 10b where projecting portions 40 are formed to reduce tackiness. However, including the step of shining ultraviolet ray in the production process contradicts the attempt to reduce the production cost of the contact member 10b. Forming projecting portions 40 in the process of molding a contact member 10b results in a lower production cost, compared with a case where the ultraviolet ray shining step is included in the production process.
When the contact member 10b has a diameter of 3 mm, 3 to 20 projecting portions 40 are formed, preferably, 4 to 15 projecting portions 40 are formed, and more preferably, 6 to 12 projecting portions 40 are formed. The projecting portion 40 has preferably a substantially semi-spherical shape. In the projecting portions 40 formed in any of the numbers described above, some may fail to be shaped perfect. However, at least three projecting portions 40 should preferably be formed perfect in shape. The projecting portions 40 are desirably disposed to be aligned regularly while being spaced apart from one another at constant intervals on the whole of one surface of the rubber-like elastic body 11. As a form of disposing the projecting portions 40, the projecting portions 40 are preferably disposed in square or in a zigzag fashion. In the case where the projecting portions 40 are disposed regularly, when the contact member 10b is bonded to the lower projecting portion 6, the contact member 10b can easily be bonded horizontally to the lower projecting portion 6.
The diameter of a bottom area of the projecting portion 40 ranges preferably from 0.1 mm to 2.0 mm, more preferably from 0.2 mm to 1.0 mm, and much more preferably from 0.4 mm to 0.6 mm. The height of the projecting portion 40 ranges preferably from 0.01 mm to 1.0 mm, more preferably from 0.03 mm to 0.50 mm, and much more preferably from 0.05 mm to 0.15 mm. The affixation of contact members 10b to each other can be reduced more by setting the size of the projecting portion 40 to those described above.
Next, an example of a production process of the contact members 10, 10a, 10b (hereinafter, referred to as “10 or the like”) described above will be described.
A most typical approach to production of the contact member 10 or the like will be as follows. Firstly, a meshed contact 12 made up of one or more layers of a metal other than a noble metal is embedded in a curable rubber composition that is in a stage before a rubber-like elastic body 11 is cured completely in such a manner that the meshed contact 12 is exposed (a meshed contact portion embedding step: S51). Following the meshed contact portion embedding step (S51), the curable rubber composition is cured (a curing step: S52). The curing step may be executed a plurality of times. Next, a highly conductive metal plating layer 30 (an example of a coat layer) having a higher conductivity than that of the metal in an outermost surface of the meshed contact 12 is formed only on a region of the meshed contact 12 exposed from the rubber-like elastic body 11 (a coat layer forming step: S53). The plating layer 30 may be formed using any method.
Firstly, a compound such as silicone rubber is metered and masticated (S101). In parallel with this, a crosslinking agent is metered (S102). The metered crosslinking agent is kneaded with the masticated compound (S103). One type or two or more types of crosslinking agents may be used. A coloring material is metered (S104), and the coloring material is kneaded with the compound that has been processed accordingly in S103 (S105). Note that the coloring material includes, for example, pigment and/or dye.
A filler is metered (S201), an auxiliary is metered (S202), and a silane coupling is metered (S203). Then, the metered filler, auxiliary and silane coupling agent are mixed together (S204). The mixed filler, auxiliary and silane coupling agent are kneaded together with the compound that has been processed accordingly in S105 (S301). Note that filler, auxiliary and silane coupling agent are not essential, and at least one of them may be added. Following this, the compound that has been processed accordingly in S301 is formed into the shape of a sheet and is then cut in an appropriate size (S302).
Next, a meshed contact 12 is prepared, and the meshed contact 12 is affixed to the sheet-formed body and is cut (S401). Following this, the sheet-formed body to which the meshed contact 12 is affixed is placed in a mold for molding. In this molding, the mold is heated, so that the sheet-formed body in the mold is subjected to a primary vulcanization (S402). Next, the mold is opened, and a molded form removed from the mold is heated to be subjected to a secondary vulcanization (S403). Next, a plating treatment using gold or the like is applied to the meshed contact 12 exposed on a rubber-like elastic body 11 (S404). Finally, the rubber-like elastic body 11 with the plated meshed contact 12 is punched in a size of a diameter of about 3 mm, whereby contact members 10 or the like are completed (S405).
The plating treatment (S404) in
For electrolytic plating, similar steps to those for electroless plating are executed except that a step of connecting wiring to the meshed contact 12 (S40451) is interposed between the rinsing (S4045) and the plating treatment (S4046). As with electroless plating, in the case of electrolytic plating, too, alkali degreasing (S4042) may be replaced by acid degreasing. In the case of electrolytic plating, metal wires 22, 23 of the meshed contact 12 function as electrodes, and ionization of the metal wires 22, 23 and deposition of gold or the like to the electrode are performed. Although as the plating layer 30 formed on the metal wires 22, 23 constituting the meshed contact 12, either of an electrolytic plating layer and an electroless plating layer will do, in selecting one of the two plating layers, the electrolytic plating layer is preferable. The reason that the electrolytic plating layer is preferable will be described as follows.
As shown in
Thus, while the preferred embodiments of the present invention have been described heretofore, the present invention is not limited to the embodiments described above but can be carried out in various modified forms.
For example, the meshed contact 12 is not limited to the one made up of the metal wires 22, 23 in the two directions that intersect each other, and hence, a contact will do which is formed by interlacing metal wires using any method, provided that the resulting contact is a meshed one. Alternatively, a contact will do which is formed using any other method than the method of interlacing such metal wires. Although the plating layer 30 is preferably the electrolytic plating layer, an electroless plating layer will do. Although the projecting portion 40 is preferably the semi-spherical member having the curved surface, the projecting portion 40 is not limited to the member that is configured so. Hence, the projecting portion 40 may be, for example, a substantially rectangular parallelepiped projecting portion of which a distal end terminates into a flat surface. The projecting portion 40 may have a shape of circular cone. In addition, steps S402 to S403 in the flow of
Next, an example of the present invention will be described. However, the present invention is not limited to the following example.
(Production Method)
A crosslinking agent (Product No.: C-25A/B, produced by Shin-Etsu Chemical Co., Ltd.) containing 0.5 parts by mass an agent A and 2.0 parts by mass of an agent B and 1.0 parts by mass of a red coloring agent (Product No.: X-93-942 produced by Shin-Etsu Chemical Co., Ltd.) were metered individually and added together to 100 parts by mass of silicone rubber compound (Product No.: KE-9510-U produced by Shin-Etsu Chemical Co., Ltd.) for kneading. Further, 1.0 parts by mass of adhesion assistant (Product No.: X-93-3046 produced by Shin-Etsu Chemical Co., Ltd.) and 1.0 parts by mass of silane coupling agent (Product No.: KBM-403 produced by Shin-Etsu Chemical Co., Ltd.) were added to 0.1 parts by mass of silica (Product Name: AEROSIL200) for kneading. Next, the resulting kneaded substance was mixed into the kneaded substance of silicone rubber compound and was then distributed into a sheet-like form of a thickness of 0.5 mm, whereby material ribbons were prepared.
Next, a 0.08 mm diameter and 120 mesh wire mesh of nickel and a one-side removable treated PET of a thickness of 25 μm were prepared, and PET, material ribbon, wire mesh and PET were layered sequentially on one another in that order. Next, this layered sheet was placed in a mold including a flat upper mold and a lower mold provided with a plurality of recessed portions to provide corresponding projecting portions on a molded form, and a compression and heating molding was executed for four minutes at 125° C. (a primary vulcanization). The mold is opened after molding, and a secondary vulcanization was executed on a molded form with PET sheets on both sides removed for 60 minutes at 175° C. As a result, a sheet was obtained in which part of the wire mesh of nickel was embedded in one side of the silicone rubber and a plurality of projecting portions are formed on a surface of an opposite side. The sheet after the secondary vulcanization was subjected to gold plating with respect to the exposed metal portion by electrolytic plating. Finally, the sheet, to which the gold plating treatment was applied, was punched using a punching die of a diameter of 3 mm, whereby contact members of a diameter of 3 mm are completed.
The contact member prepared in the manner described above was placed in a mold prepared to mold a rubber key pad, and a silicone rubber producing material was supplied into the mold for molding. As a result, a push-button switch member was obtained which had a meshed contact at a contact portion.
(Evaluation)
(1) Keying Durability Test
The push-button switch member was fixed to a comb teeth-like gold plated circuit board having electrodes of which an electrode width was 0.5 mm, an electrode gap was 0.5 mm, and a thickness was a copper foil thickness of 35 μm+Ni plating thickness of 3 μm+Au plating thickness of 0.3 μm, and keying was performed up to 500,000 times under a load of 6 N/key and at a keying speed of three times per second, and when the number of times of keying reached a predetermined number of times of keying, a contact resistance value was measured using the ADVANTEST R6561 DIGITAL MULTIETER as a measuring. When the measured contact resistance values did not differ greatly from initial values, and a failure in external appearance such as dislocation of the metal wires was not recognized, the push-button switch member was recognized as being “acceptable”.
As shown in Table 1, no remarkable increase in contact resistance value was recognized in the keying test up to 500,000 times. Additionally, nothing abnormal was recognized in external appearance.
(2) High Temperature and High Humidity Durability Test
An environment test was carried out using a push-button switch member prepared under the production conditions described above. As a comparison, a push-button switch member having the contact member mounted thereto was used which was prepared without executing the step of applying a gold plating in the production method of the example. Contact resistance values were measured under a load of 9 N using the ADVANTEST R6561 DIGITAL MULTIETER as a measuring. Contact resistance values were measured using the comb teeth-like gold plated circuit board having electrodes of which an electrode width was 0.5 mm, an electrode gap was 0.5 mm, and a thickness was a copper foil thickness of 35 μm+Ni plating thickness of 3 μm+Au plating thickness of 0.3 μm. A high temperature and high humidity condition (room temperature of 65° C., room humidity of 95% RH, storage time of 500 hours) was adopted as environment condition. Then, contact resistance values were measured before the test (at the time of start), 240 hours (240H) later, and 500 hours (500H) later. In Table 2, values given in rows of Max., Min., and Av. are those obtained under a condition of N=12. In evaluating the results of the high temperature and high humidity durability test, when the measured contact resistance values did not differ greatly from initial values, and a failure in external appearance was not recognized (that is, neither a dislocation of the metal wires nor a remarkable generation of corrosion product was recognized), the push-button switch member was recognized as being “acceptable”.
As shown in Table 2, a reduction in contact resistance value due to application of the gold plating was recognized, and it was recognized that an increase in contact resistance value was suppressed even under the high temperature and high humidity condition. Additionally, nothing abnormal in external appearance was recognized.
The present invention can be applied to a device including a push-button switch.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-198822 | Oct 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/035767 | 10/2/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2018/066490 | 4/12/2018 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20110266129 | Inagaki | Nov 2011 | A1 |
| 20160372276 | Han | Dec 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| S62-54433 | Apr 1987 | JP |
| H3-57828 | Jun 1991 | JP |
| H8-276435 | Oct 1996 | JP |
| 2004-342539 | Dec 2004 | JP |
| 2012-185956 | Sep 2012 | JP |
| 2014-240058 | Dec 2014 | JP |
| Entry |
|---|
| International Search Report in PCT/JP2017/035767, dated Dec. 19, 2017, 4pp. |
| Number | Date | Country | |
|---|---|---|---|
| 20190287739 A1 | Sep 2019 | US |
