De-bouncing keypad and preparation method thereof

A de-bouncing keypad, comprising:

• a rubber substrate;
• and
• a metal contact, which is a layered complex including a first layer, a second layer, and a third layer, attached with the rubber substrate,
• wherein the first layer is a rubber layer having a thickness of 0.1-10 mm,
• wherein the second layer is a sheet metal layer having a thickness of 0.1-10 mm and containing magnesium, aluminum, titanium, chromium, manganese, ferrum, cobalt, nickel, copper, zinc, niobium, molybdenum, silver, tin, tantalum or tungsten, and
• wherein the third layer is a tin alloy plated layer or lead alloy plated layer having a thickness of 0.1-10 μm selectively deposited onto the second layer.

A method of preparing a de-bouncing keypad, the method comprising:

• (1) treating sheet metal, wherein the sheet metal is a stainless steel sheet, a copper or copper alloy sheet, and a nickel or nickel alloy sheet having a thickness of 0.01-1.0 mm by:
• using a cleaning agent and an organic solvent to deoil and clean the sheet metal,
• mechanically roughing a surface of the sheet metal through sand blasting and polishing,
• processing the sheet metal through chemical etching into concave pits or convex points having a diameter less than 1 mm, or
• plating a pure nickel layer or a nickel alloy layer, and a cobalt or cobalt alloy layer having a thickness of 0.1-10 μm on one side or two sides of the sheet metal by electroplating or chemical plating, then using the cleaning agent and the organic solvent to deoil and clean the sheet metal obtained,
• (2) adhering a hydrophobic rubber to the sheet metal by:
• adhering a hydrophobic rubber layer onto the sheet metal plated with a prime coat or an adhesion promoter through heat vulcanization adhesion and heat vulcanization shaping, to form a layered composite sheet, or
• adhering the hydrophobic rubber layer with self-adhesiveness on the sheet metal plated with a prime coat or not plated with a prime coat through heat vulcanization adhesion and heat vulcanization shaping, to form a layered composite sheet,
• (3) cutting the layered composite sheet by separating or punching the layered composite sheet into an object, wherein the object is a cylinder comprising the hydrophobic rubber layer and the sheet metal layer having a diameter of 2-10 mm or the object has a cross section in a shape of ellipse, polygon, crisscross, star or crescent or any combinations thereof, and using a basic cleaning liquid to wash the object for about 5 min, washing the object by water, then using 5% hydrochloric acid to clean the object for about 1 min, using deionized water to clean the object, and then draining off the object;
• (4) preparing a plated layer by
• dipping the object in a chemical plating bath containing a soluble tin or lead compound and stirring to form the plated layer on a metal surface of the object by chemical plating, or
• putting the object into a roller for a chemical plating bath containing a soluble tin or lead compound and making the roller rotate and form a plated layer on the metal surface of the object by chemical plating;
• wherein the chemical plating bath contains 5-100 g/L soluble tin compound or lead compound, 5-100 g/L complexing agent, 5-100 g/L reducing agent and 2-50 g/L pH regulator,
• (5) cleaning and drying the plated object by taking out the plated object, using distilled water or deionized water to rinse the object, then draining the object off, and using cold air to blow-dry, or putting the object into a 70° C. constant temperature oven to dry, thus obtaining a contact with a metal surface layer plated with a tin alloy or lead alloy;
• (6) applying the contact obtained in step (5) to step (7) or applying the object before or after to step (7), and performing after-plating treatment on the contact plated with the tin alloy or lead alloy, wherein a method for after-plating treatment comprises applying a layer of water-soluble or an organic solvent tin alloy protective agent or a tin plated layer surface inhibitor on a surface of the tin alloy or lead alloy of the contact using a leady alkaline solution to treat the contact plated with the tin alloy to replace partial tin on the surface of the contact with lead, to form a tin lead alloy on the surface of the contact;
• and
• (7) performing heat vulcanization adhesion and heat vulcanization shaping on the metal contact and the rubber, wherein the rubber layer in the metal contact is combined with other rubber in the metal contact while shaping, and prepared into a de-bouncing rubber keypad, or preparing the plated layer firstly, then performing adhesion treatment on the sheet metal having the plated layer with the hydrophobic rubber layer, to prepare a composite sheet having the plated layer.

A method of preparing a de-bouncing keypad, the method comprising:

• (1) treating a sheet metal layer, which is a stainless steel sheet, a copper or copper alloy sheet, and a nickel or nickel alloy sheet having a thickness of 0.01-1.0 mm;
• either by roughing one side or two sides of the stainless steel, copper or copper alloy, nickel or nickel alloy sheet through mechanical polishing, sand blasting and chemical etching, or plating a pure nickel layer or a nickel alloy layer, a pure cobalt layer or a cobalt alloy layer, and a molybdenum layer or a molybdenum alloy layer having a thickness of 0.05-10 μm through a vacuum plating, electroplating or chemical plating method, or only cleaning the sheet;
• (2) adhering a hydrophobic rubber layer onto the sheet metal layer plated with a prime coat or an adhesion promoter through heat vulcanization adhesion and heat vulcanization shaping, to form a composite sheet, or adhering the hydrophobic rubber with self-adhesiveness on a sheet metal layer plated with a prime coat or not plated with a prime coat through heat vulcanization adhesion and heat vulcanization shaping, to form a composite sheet;
• (3) dipping the composite sheet in an electroplating bath containing a soluble tin or lead compound to form a tin alloy or lead alloy plated layer on a metal surface of the composite sheet by electroplating, the electroplating bath containing 5-100 g/L soluble tin compound or lead compound, 0-100 g/L complexing agent and 10-120 g/L pH regulator;
• (4) applying the sheet to step (5) or applying a cylinder before or after step (5), and performing after-plating treatment on the sheet plated with the tin alloy or lead alloy, wherein a method for after-plating treatment comprises applying a layer of water-soluble or an organic solvent tin alloy protective agent or a tin plated layer surface inhibitor on a surface of the tin alloy or lead alloy of the sheet;
• or coating a layer of a complex of non-conductive lubricating oil, lithium-based grease or silicone having arc extinction and lubrication effects on the surface of the tin alloy or lead alloy of the sheet, wherein commercialized arc extinction grease is preferably selected;
• or using a leady alkaline solution to treat the sheet plated with the tin alloy to replace partial tin on the surface of the sheet with lead, to form a tin lead alloy on the surface of the sheet;
• (5) separating or punching the composite sheet in step (6) into a cylinder comprising a rubber layer, a sheet metal layer and a plated layer and having a diameter of 2-10 mm;
• and
• (6) taking the cylinder as a metal contact to perform heat vulcanization adhesion and heat vulcanization shaping with the rubber, wherein the rubber layer in the metal contact above is combined with other rubber in the rubber layer while shaping, and prepared into a de-bouncing rubber keypad;
• or, preparing the plated layer firstly, then performing adhesion treatment on the sheet metal having the plated layer with the hydrophobic rubber layer, to prepare a composite sheet having the plated layer.