CN111048340A - Method for improving reliability of rubber and metal composite electric contact - Google Patents
Method for improving reliability of rubber and metal composite electric contact Download PDFInfo
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- CN111048340A CN111048340A CN201911322759.0A CN201911322759A CN111048340A CN 111048340 A CN111048340 A CN 111048340A CN 201911322759 A CN201911322759 A CN 201911322759A CN 111048340 A CN111048340 A CN 111048340A
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- 238000005530 etching Methods 0.000 claims abstract description 33
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- 238000003631 wet chemical etching Methods 0.000 claims description 2
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- 150000002736 metal compounds Chemical class 0.000 abstract 1
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Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
- H01H11/04—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts
- H01H11/06—Fixing of contacts to carrier ; Fixing of contacts to insulating carrier
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/04—Co-operating contacts of different material
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Laminated Bodies (AREA)
Abstract
The invention discloses a method for improving the reliability of a rubber and metal composite electric contact, which comprises the following steps: firstly, at least partially etching the inner surface of a metal sheet compounded with rubber by an etching process before the rubber and the metal sheet are compounded and molded, so that a fresh surface is generated on the inner surface of the metal sheet; step two, treating the inner surface of the metal sheet by using an adhesive, a primer or a coupling agent, or using self-adhesive rubber to realize the composite molding of the rubber and the metal sheet, wherein the rubber and the metal sheet are bonded together; and step three, cutting the sheet formed by compounding the rubber and the metal sheet into small wafers to obtain the electric contact. The inner surface of the metal sheet compounded with the rubber is partially etched through the etching process, so that the inner surface of the metal sheet has a fresh partial surface, and the metal sheet and the rubber can be firmly combined because the metal sheet does not contain any grease brought by the metal sheet, the metal sheet is prevented from being separated, and the reliability of the rubber and the metal compound type electric contact is ensured.
Description
Technical Field
The invention belongs to the field of materials or high polymer materials, and particularly relates to a method for improving the reliability of a rubber and metal composite electric contact.
Background
Rubber keys are used in remote controls, games, handsets, power tools, medical devices and automobiles, and one of the key components of a rubber key is an electrical contact (also called a "conductive particle") which, when pressed, contacts a PCB and functions as a circuit switch.
The invention patent 'composite conductive sheet' with Chinese patent application number of 201010592410.1 provides a composite conductive sheet composed of a polymer matrix and a metal foil, wherein the surface of the metal foil is uneven. The invention patent 'pitted surface metal and rubber composite conductive particle' with Chinese patent application number of 201110193369.5 discloses a composite conductive particle of pitted surface metal and rubber, wherein the metal surface is a pitted surface and is provided with pits, salient points or both. The invention patent 'a noble metal plated switch contact element and a preparation method thereof' of Chinese patent application No. 201410467116.6 discloses a method for preparing a noble metal switch contact element on the outer surface of a metal layer through plating resistance, plating and etching processes. The invention patent 'a multilayer porous metal and high polymer material composite sheet' of chinese patent application No. 201610798351 discloses a two-layer or multilayer porous metal and high polymer material composite sheet, and an electrical contact made of the composite sheet, the material composition of the two outer surfaces of the electrical contact is consistent, and the contact resistance is low.
These above patents all focus on the outer surface of the electrical contacts (the side of the electrical contacts that may contact the PCB). The attention on the inner surface of the electrical contact is limited to the use of adhesives and primers between the metal layer and the polymer material layer to enhance the adhesive strength between the metal layer and the polymer material layer. However, in the production practice, no matter how to strengthen the cleaning of the metal sheet, no matter how to enhance the adhesion by using various adhesives, or no matter how to use self-adhesive rubber as the polymer material layer, no matter what quality or brand of polymer material is used, no matter what vulcanization molding process is used, no release agent is used in the vulcanization molding process, no matter whether the vulcanization mold is cleaned, one hundred percent of firm adhesion between the metal layer and the polymer material layer (or the rubber layer) in the produced rubber-metal composite electric contact can not be maintained, and the metal layer can not fall off. The metal layer drops by itself, or the electric contact dropped after the metal layer lightly touches sometimes reaches the ppm level, which seriously affects the product quality and the production efficiency. This is probably due to the fact that the metal strip used for the production of the rubber-metal composite electrical contact is subjected to various contaminations during its production and transport, and the surface of the metal strip is provided with visible and invisible oil stains, rusts, dust impurities, chemicals such as paraffin, metal brighteners, etc., which, however, are not necessarily cleaned well by intensive cleaning processes. In such a case, even if the other process or material is preferable, it is not possible to ensure that the metal layer and the polymer material layer (or the rubber layer) are firmly bonded and the metal layer does not fall off.
In the rubber-metal composite type electrical contact, if separation occurs between the metal layer and the polymer material layer, the metal layer is peeled off, which not only makes the switching function of the key ineffective, but also may cause personal safety accidents, particularly in the case where such an electrical contact is used in an automobile.
Therefore, in the rubber-metal composite electrical contact industry, a method for preventing the metal layer from falling off is urgently needed.
Disclosure of Invention
The purpose of the invention is as follows: the invention discloses a method for improving the reliability of a rubber-metal composite electric contact, which is used for preventing a metal layer in the electric contact from falling off.
The technical scheme is as follows: the invention provides a concrete feasible method for improving the reliability of a rubber-metal composite electric contact, which comprises the following steps: the inner surface of the metal sheet, which is compounded with rubber, is at least partially etched by an etching process prior to the compounding of the rubber and the metal sheet, so that the inner surface of the metal sheet produces a fresh surface. Then, the inner surface of the metal sheet is treated by an adhesive, a primer or a coupling agent, or self-adhesive rubber is used to realize the heat vulcanization composite molding of the rubber and the metal sheet, and the rubber and the metal sheet are bonded together. Finally, the sheet material formed by compounding the rubber and the metal sheet is cut into small circular sheets with the diameter of 1.0-10.0 mm. The small round piece is the rubber-metal composite conductive particle. Each of the small metal sheets has at least one fresh etched surface, such as a circular fresh surface with a diameter of 0.25 mm. The fresh surface has enough metal characteristics, does not contain pollutants such as oil stains, metal brightening agents and the like brought by the surface of the metal sheet in the production and transportation processes, and is easy to be firmly bonded with rubber.
The fresh surface is in the shape of a circle, an ellipse, a square, a line or other geometric shapes when viewed from the surface of the metal sheet, and can be in the shape of a cylinder, a truncated cone, a sphere, a spherical cap or other regular or irregular shapes when viewed from the cross section. The area of each fresh surface is not more than one fifth of the surface area of one surface of the metal sheet in the rubber-metal composite type electric contact, so that more than two fresh surfaces are ensured on the inner surface of the nickel sheet of each electric contact before the nickel sheet is composited with the rubber, and good combination between the rubber and the metal sheet is facilitated.
The fresh surface is recessed, the depth of the recess being less than one half of the thickness of the metal sheet; the shape of the depression is spherical crown, hemispherical, semi-ellipsoidal, truncated spherical, cylindrical, truncated conical, prismatic, pyramidal, truncated pyramidal, or irregular geometric shape. The depth of the fresh surface depression is less than one-half of the thickness of the metal sheet, which ensures that when both sides of the metal sheet are etched to the same depth, no perforation occurs in the metal sheet.
In the production of metal sheets, it is generally necessary to perform rolling using vegetable oil, mineral oil or lubricating grease, and sometimes chemicals such as a metal protectant, brightener or bright oil are used. Downstream sheet metal users often cannot determine and control the specific composition of the greases and chemicals used in the sheet metal production process. These greases or chemicals inevitably remain on the metal sheet. Before use, the grease or chemicals attached to the surface of the metal sheet need to be removed. For this reason, many cleaning methods such as an alkaline cleaning solution cleaning method, a solvent cleaning method, an electrolytic cleaning method, and the like have been developed by technologists. However, whether the various cleaning methods are effective at all percent is the productionIt is often difficult to judge in practice. Undoubtedly, the cleaning of the metal sheet before the compounding with the rubber is an important process for ensuring the bonding quality, and is a commonly used and popular process. However, the cleaning process cannot ensure that the metal piece and the rubber are firmly bonded and the metal piece does not fall off in each electrical contact regardless of the reinforcement. To this end, the invention discloses the pre-etching of the metal sheet to create a plurality of fresh surfaces to ensure that there is at least one fresh surface for each electrical contact, even if the fresh surfaces are as small as 0.01mm in area2Because the fresh surface energy and the rubber are firmly adhered, the metal sheet can be ensured not to fall off, and the phenomenon that the electric contact falls off by light collision in the installation and use processes is avoided.
Any etching process that produces a fresh metal surface on the metal sheet may be used, such as chemical, laser, plasma, electron beam or ion beam etching processes, and the like. The inner surface of the metal sheet may be etched only in advance, or both the inner surface and the outer surface of the metal sheet may be etched before the metal sheet and the rubber are compounded. The shapes of the inner and outer surfaces of the metal sheet after the etching process prior to the compounding of the metal sheet and the rubber may be different, may be uniform or substantially uniform. For example, uniformly distributed pits with a diameter of about 0.25mm and a depth of about 0.03mm are etched into both the inner and outer surfaces of the metal sheet. Or, pits with the diameter of about 0.25mm and the depth of about 0.03mm are evenly distributed on the outer surface of the metal, and pits with the diameter of about 0.25mm and the depth of about 0.015mm are evenly distributed on the inner surface of the metal.
The metal sheet may be made of a metal that is relatively stable at room temperature, such as gold, silver, copper, zinc, molybdenum, iridium, tungsten, cobalt, nickel, indium, iron, platinum, rhodium, palladium, tin, titanium, or an alloy of one of these metal elements. As a specific example of the metal sheet, stainless steel, nickel or a nickel alloy, cobalt or a cobalt alloy is preferable.
The invention requires that the metal sheet of each electrical contact has at least one fresh surface etched away before it is compounded with rubber. The fresh surface may be of various shapes. As an example, a plurality of pits with the diameter of about 0.25mm are etched on both surfaces of a nickel sheet with the thickness of 0.075-0.10mm by a wet chemical etching or laser etching method, the shape of each pit is cylindrical, truncated cone, conical, truncated pyramid, hemispherical, spherical crown or other irregular shapes, the depth of each pit is 0.025-0.035mm, and the distance between the axial centers of two adjacent pits is about 0.75 mm. The depth of the pits on the inner and outer surfaces needs to be well controlled. The pits on the outer surface are beneficial to improving the dust resistance of the electric contact in use. In particular, the pits on the inner surface do not need to be too deep, and a fresh metal surface can be generated under proper process conditions.
Although many rubbers can be used to prepare the rubber-metal composite type electrical contact, in the present invention, silicone rubbers, including thermosetting silicone rubbers or self-adhesive silicone rubbers, are preferably used because of their excellent high and low temperature resistance, chemical stability and elasticity. The thermosetting silicone rubber may be prepared from liquid silicone rubber or solid silicone rubber. The thickness of the silicone rubber layer is 0.1-1.0 mm. The shape of the outer surface of the silicon rubber in the composite electric contact is not limited, the surface of the silicon rubber is flat, or the material is a cylinder, a cone or a cone with the raised height of the silicon rubber being 0.01-1.0mm and the diameter of the cross section being not more than 2.0 mm.
In order to ensure a certain adhesive strength between the metal sheet and the silicone rubber, a self-adhesive silicone rubber having adhesiveness to the metal sheet itself may be used, or an adhesive, an adhesion promoter, a primer or a coupling agent for improving the adhesive strength between the metal sheet and the rubber may be coated on the inner surface of the metal sheet, or on the inner surface and the outer surface thereof in an average thickness of not more than 1 μm. The application of a layer of adhesive, adhesion promoter, primer or coupling agent to the outer surface of the metal sheet is not necessary to improve the adhesion strength between the metal sheet and the rubber, and its thickness must be controlled, otherwise it has an effect on the electrical conductivity of the electrical contact. Dip coating is a simple and economical process, but it tends to coat both sides of the metal sheet.
The rubber-metal sheet composite sheet may be of large size. The rubber-metal composite electrical contact is a small round piece with the circumscribed circle diameter of 1-10mm, which is prepared by mechanically punching or laser cutting the large-size rubber-metal composite sheet prepared by the method. The electrical contacts may be circular, square or other shapes.
Has the advantages that: the rubber-metal composite electric contact prepared by the invention has the advantages that the metal sheet has a fresh metal surface before being compounded with rubber, uncontrollable factors such as pollution brought by the metal sheet are eliminated, the reliable bonding strength is ensured between the rubber and the metal sheet, the metal sheet is effectively prevented from falling off, the reliability and the safety of the electric contact are improved, and the electric contact has good application prospect. By adopting the method provided by the invention, the phenomenon that the metal sheet in the rubber-metal composite electric contact falls off is avoided.
Drawings
Fig. 1 is a schematic sectional view of an electrical contact of embodiment 1 of the present invention.
Fig. 2 is a schematic sectional view of an electrical contact of embodiment 2 of the present invention.
In the figure, 1, a metal sheet (stainless steel); 2. rubber (silicone rubber).
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below so that those skilled in the art can better understand the advantages and features of the present invention, thereby making the scope of the present invention more clearly defined. The embodiments described herein are only a few embodiments of the present invention, rather than all embodiments, and all other embodiments that can be derived by one of ordinary skill in the art without inventive faculty based on the embodiments described herein are intended to fall within the scope of the present invention.
Example 1
The stainless steel sheet of 0.08mm thickness was cleaned to remove as much as possible the oily stains on the surface of the sheet. Through a laser etching method, a plurality of pits with the pit opening diameter of 0.25mm are formed on two surfaces of the stainless steel sheet through laser etching, the shape of each pit is cylindrical, the depth of each pit is 0.030 +/-0.005 mm, and the distance between the axial centers of two adjacent pits is 0.75 mm. After dip-coating the stainless steel sheet with a primer for improving adhesion with the silicone rubber, the stainless steel sheet is molded with methyl vinyl silicone rubber containing 0.5% of 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane for 10min at about 165 ℃, and the silicone rubber and the stainless steel sheet are adhered together to form a silicone rubber-stainless steel sheet with the thickness of 0.85 mm.
And punching the obtained silicon rubber-stainless steel sheet into a small wafer with the diameter of 3.5mm to obtain the rubber-metal composite electric contact. The outer surface of the electrical contact thus obtained has a certain resistance to dust in use, due to the presence of the pits. Because the inner surface (the surface combined with the silicon rubber) of the stainless steel in each electric contact is provided with more than ten fresh surfaces etched by the laser, the fresh surfaces do not have any oil stain, stain and special chemicals, the inner surface of the stainless steel is firmly bonded with the silicon rubber, and the stainless steel is prevented from falling off from the silicon rubber.
Example 2
Essentially the same as example 1, but with the depth of the laser etched pits on both sides of the stainless steel being different. During laser etching, the depth of a cylindrical pit etched on one surface of the stainless steel is 0.03-0.05mm, and the depth of a pit etched on the other surface of the stainless steel is 0.001-0.01 mm. The surface with the pit depth of 0.03-0.05mm is exposed in the rubber-stainless steel sheet to form the outer surface of the composite sheet, and the surface with the pit depth of 0.001-0.01mm is combined with the silicone rubber to form the inner surface.
The rubber-metal composite electric contact prepared by the method has good dust resistance, and meanwhile, the laser etching depth of the inner surface of the metal layer is smaller, so that the laser etching time is favorably shortened, and the production efficiency is improved.
Example 3
The pattern for exposure is designed first. Cleaning a nickel sheet with the thickness of 0.10mm and the nickel content of more than 99.5 percent, then respectively printing a layer of cured photosensitive resist with the thickness of 3-9 mu m and washed off by alkali liquor on two surfaces of the nickel sheet by a metal screen printing method, drying, exposing according to a designed pattern, developing (namely washing off the photosensitive resist on the unexposed part by water), thereby preparing the nickel sheet with the two surfaces covered by the cured photosensitive resist film and exposed metal (namely nickel) small round points which are uniformly distributed. The diameter of the metal small dots is 0.2mm, and the distance between the centers of two adjacent metal small dots is 0.65 mm.
Etching the nickel sheet protected by the photosensitive resist by using an acidic etching solution containing ferric trichloride or copper chloride, and etching small pits with the depth of 0.025-0.040mm at the exposed small metal round points on the nickel sheet protected by the photosensitive resist. And cleaning the nickel plate protected by the photosensitive resist with a sodium hydroxide solution, removing the photosensitive resist on two sides of the nickel plate, rinsing the nickel plate with deionized water, and drying for later use.
The recipe of one etching solution used in this example was: every 100g of etching solution contains 8g of ferric chloride, 10g of 30% hydrogen peroxide, 8g of citric acid, 8g of sodium citrate, 0.1g of thiosemicarbazide and the balance of water. The above formula is prepared for use immediately. A square nickel plate with the side length of 100mm, which is protected by the photosensitive resist but has small metal dots exposed uniformly, is etched by the etching solution. The nickel plate was put into 2L of an etching solution at 20 ℃ and stirred. And taking out after 20 minutes. Washing with tap water and deionized water, washing with anhydrous ethanol, and air drying or oven drying. Each exposed metal dot is etched to a depth of about 30 μm to produce a fresh metal surface in the shape of a spherical cap. Because the thiosemicarbazide is added into the etching solution, the obtained etching surface is bright.
And treating one or two surfaces of the obtained nickel sheet with an adhesive, a primer or a coupling agent, and then carrying out hot vulcanization molding on the treated nickel sheet and the silicon rubber to obtain the sheet-shaped composite material containing a layer of nickel sheet and a layer of silicon rubber. The specific treatment method comprises the following steps: a commercially available primer for the hot vulcanization adhesion of metal and silicone rubber (Chemlok 608 manufactured by Lord chemical (Shanghai) Co., Ltd.) is diluted by 7.5 times with a mixed solution of anhydrous ethanol and xylene in a ratio of 1:1, and the mixture is uniformly mixed to obtain the primer to be used. The primer is brushed on one surface (inner surface) of the nickel sheet, or the nickel sheet is taken out after being soaked in the primer for 15 seconds and then baked for half an hour at 70 ℃. The nickel sheet and the methyl vinyl silicone rubber containing 0.5% of peroxide DCP were vulcanized at 170 ℃ for 6 minutes, and the inner surface of the nickel sheet was bonded to the silicone rubber to form a nickel sheet-silicone rubber laminate.
And (3) punching and cutting the layered composite material into small wafers with the diameters of 2.5mm, 3.0mm and 5.0mm to obtain the rubber-metal composite electric contact. The inner surface (the surface combined with the silicon rubber) of the nickel sheet in each electric contact is provided with more than ten fresh metal surfaces which are etched before being combined with the silicon rubber, and the fresh surfaces are free from pollution of oil stains and the like, so that firm adhesion between the nickel sheet and the silicon rubber is ensured. And the outer surface of the nickel sheet in each electric contact is provided with small etched pits, so that the dust resistance of the electric contact is improved.
The method disclosed in this example was adopted to perform trial production, and a total of more than 1000 ten thousand rubber-metal composite electrical contacts with a diameter of 3.0mm were produced and used on silicone rubber keys, and after manual peeling examination of the metal sheets of the conductive particles in all keys before shipment, no metal sheet was peeled off. Without the prior art method of pre-treating the metal pieces to create a fresh surface prior to bonding with the silicone rubber, the quality problem of 1 or several metal pieces falling off the electrical contacts by themselves or with a light touch by hand, has occurred per one million electrical contacts.
Example 4
The materials and processes used in this example were the same as in example 3, but the exposure pattern was designed such that a parallel concave line was etched into the inner and outer surfaces of a 0.10mm thick nickel plate. The depth of the concave lines is 0.025-0.035mm, and the width of the concave lines from the outer surface or the inner surface of the nickel plate is 0.2 mm. The distance between two adjacent concave lines is 0.2-0.5 mm. The concave lines in the nickel sheet are vertical to the concave lines on the outer surface of the nickel sheet.
The rubber-metal composite electric contact prepared from the nickel sheet can ensure firm adhesion between the nickel sheet and the rubber, and has good dust resistance.
Example 5
The embodiment uses a dry film process, and uses a dry film having a three-layer structure of a PE protection film, a dry film layer and a PET protection film, wherein the thickness of the dry film is 2 mil. Removing the protective film of the dry film, respectively pressing on two surfaces of a nickel sheet with the thickness of 0.10mm, exposing and developing to obtain the nickel sheet with the two surfaces covered by the dry film and exposed metal (namely nickel) small dots which are uniformly distributed. As in example 3, the diameter of the metal dots is 0.2mm and the distance between the centers of two adjacent metal dots is 0.65 mm.
The dry film is etched by the acid etching solution containing ferric trichloride used in the embodiment 3 or a plasma etching machine, small pits with the depth of about 0.03mm are etched at the small exposed metal round points, then the dry film on the nickel plate is removed, and the nickel plate is cleaned. The obtained nickel sheet and self-adhesive silicone rubber are compounded by thermal vulcanization to form a silicone rubber-nickel sheet with the thickness of 0.8 mm. When the self-adhesive silicon rubber and the nickel sheet are bonded by hot vulcanization, the nickel sheet can be bonded with the self-adhesive silicon rubber without pre-treating the nickel sheet by using an adhesive, a primer or a coupling agent. Because the surface of the nickel sheet is etched to form a fresh small circular surface before the self-adhesive silicon rubber is thermally vulcanized and bonded, the firm bonding of a production line between the self-adhesive silicon rubber and the nickel sheet is ensured, and the nickel sheet can not fall off from the silicon rubber once colliding.
And (3) punching and cutting the obtained silicon rubber-nickel sheet into small round particles with the diameter of 3mm, 5mm or other sizes to obtain the rubber-metal composite electric contact with the nickel sheet and the silicon rubber firmly bonded and having excellent dust resistance.
The above examples are intended to illustrate some of the practice of the invention. It will be apparent to those skilled in the art that various changes, modifications and alterations can be made without departing from the principles of the invention, and such changes, modifications and alterations should also be viewed as being within the scope of the invention.
Claims (10)
1. A method for improving the reliability of a rubber and metal composite electric contact is characterized in that: the method comprises the following steps:
firstly, at least partially etching the inner surface of a metal sheet compounded with rubber by an etching process before the rubber and the metal sheet are compounded and molded, so that a fresh surface is generated on the inner surface of the metal sheet;
step two, treating the inner surface of the metal sheet by using an adhesive, a primer or a coupling agent, or using self-adhesive rubber to realize the composite molding of the rubber and the metal sheet, wherein the rubber and the metal sheet are bonded together;
step three, cutting the sheet formed by compounding the rubber and the metal sheet into small wafers with the diameter of 1.0-10.0mm, namely the rubber-metal compound electric contact; at least one etched area of each metal sheet of the rubber-metal composite electric contact is not less than 0.01mm2The fresh surface to which the rubber is bonded.
2. A method of improving the reliability of a rubber and metal composite electrical contact according to claim 1, wherein: the fresh surfaces are in a circular shape, an oval shape, a square shape, a line shape or other geometric shapes when viewed from the surface of the metal sheet, and the area of each fresh surface is not more than one fifth of the surface area of one surface of the metal sheet in the rubber-metal composite electric contact; the fresh surface is recessed, the depth of the recess being less than one half of the thickness of the metal sheet; the shape of the depression is spherical crown, hemispherical, semi-ellipsoidal, truncated spherical, cylindrical, truncated conical, prismatic, pyramidal, truncated pyramidal, or irregular geometric shape.
3. A method of improving the reliability of a rubber and metal composite electrical contact according to claim 1, wherein: the etching process is a chemical etching, electrical etching, laser etching, plasma etching, electron beam etching or ion beam etching process; the chemical etching process is characterized in that after exposure plate making and development are carried out, a protective film of an area to be etched is removed, and the area is contacted with a chemical solution during etching, so that the effect of dissolution and corrosion is achieved, and the etching effect is generated; the electroetching process is characterized in that under the action of a power supply, the unprotected metal surface is subjected to anodic dissolution in an electrolyte solution, so that the purpose of etching is achieved; the laser etching, plasma etching, electron beam etching or ion beam etching process is dry etching, and is characterized in that the energy of laser, plasma, electron beam or ion beam is respectively utilized to act on the surface of an etched object to knock out atoms of the etched object material, thereby achieving the purpose of etching by utilizing physical energy transfer.
4. A method of improving the reliability of a rubber and metal composite electrical contact according to claim 1, wherein: the inner and outer surfaces of the metal sheet are both subjected to an etching process prior to the metal sheet and rubber being compounded.
5. A method of improving the reliability of a rubber and metal composite electrical contact according to claim 1, wherein: before the metal sheet and the rubber are compounded, the inner surface and the outer surface of the metal sheet are subjected to an etching process to obtain a consistent shape.
6. A method of improving the reliability of a rubber and metal composite electrical contact according to claim 1, wherein: the metal sheet is gold, silver, copper, zinc, molybdenum, iridium, tungsten, cobalt, nickel, indium, iron, platinum, rhodium, palladium, tin, titanium, or an alloy of one of these metal elements.
7. A method of improving the reliability of a rubber and metal composite electrical contact according to claim 1, wherein: a plurality of pits with the pit mouth diameter of 0.25mm are etched on two surfaces of a nickel sheet with the thickness of 0.075-0.10mm by a wet chemical etching or laser etching method, the shape of each pit is cylindrical, truncated cone, conical, truncated pyramid, hemispherical, spherical crown or other irregular shapes, the depth of each pit is 0.025-0.035mm, and the distance between the axle centers of two adjacent pits is 0.75 mm.
8. A method of improving the reliability of a rubber and metal composite electrical contact according to claim 1, wherein: the rubber is silicon rubber: thermosetting silicone rubber or self-adhesive silicone rubber; the thickness of the silicon rubber layer is 0.1-1.0mm, the surface of the silicon rubber is flat, or the material is a cylinder, a cone or a cone with the raised height of the silicon rubber being 0.01-1.0mm and the diameter of the cross section being not more than 2.0 mm.
9. The method of claim 1, wherein the metal sheet is coated on its inner surface, or both the inner surface and the outer surface with a layer of adhesive, adhesion promoter, primer or coupling agent having an average thickness of not more than 1 μm for improving the adhesion between the metal sheet and the rubber.
10. A method of improving the reliability of a rubber and metal composite electrical contact according to claim 1, wherein: the electric contact is a small round piece with the circumscribed circle diameter of 1-10mm, which is manufactured by mechanical punching or laser cutting.
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