It seemed that Metal Dome is a strange and mystery products in most people eyes, esp. to the green handle in this industry, and not mention person outside of our industry. Also sometimes my clients ask about the questions of technology or parameter of Metal Domes, such as what is a CP or CL is, how the plating, and so on. Today, I will talk something about these things, with the hope of covering basic technology and parameter in the fields of Metal Domes.
1, Material of Metal Domes
Generally it is SUS 301 or SUS 304. The hardness of SUS 301 is higher than SUS 304, normal between 490 and 530 Hv (Tensile Strength 186kg/mm²). Or sometimes people divided them into four basic types, according to the hardness of Japanese pencil: 1/4 H, 1/2 H, H and EH. The higher the hardness, the more stability of life cycles and click feeling, and the more expensive price will be. For more information about material, view About Stainless Steel – Raw Material of Metal Dome (1), About Stainless Steel – Raw Material of Metal Dome (2)
2, Number of Sockets in Mould of Metal Domes
The more number of sockets in mould, the less stability will be. Right now, it is 1 out 1, for the normal factory of metal domes, for small circle metal dome, such as 3~5mm, maybe 3 or 5 pcs.
3, OQA Control
The items of OQA including outlook(shape, burs), force (force tester), click feeling, life testing (life tester), generally inspect 3 out 10,000 pcs randomly.
4, Click Feeling
CC: Click Feeling; CP: Compression Peak Force; CL: Compression Low Force; RL: Release Low Force; RP: Compression Peak Force
CC(%)=(CP-CL)/CP x 100%, it’s normally between 35% and 60%.
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5, Stroke (Travel) of Metal Domes
Please see the figure, generally the stroke (travel) for Diameter 4mm metal dome is 0.16mm “ 0.18mm, +/- 0.003mm, Dia 5mm 0.18mm “ 0.23mm and 0.23mm “ 0.28mm for Dia 6mm.
6, Height of Metal Domes
Height equal to stroke (travel) + thickness of material. For examples, the stroke is 0.20mm, thickness of material is 0.06, then height will be 0.20+0.06=0.26mm.
7, Shape of Metal Domes
There are basic four types: Circle (Round), Four-Legs (Cross), Triangle and Oblong. Also customers design is welcome.
8, Handling of Smudge
Cleanout: There are two methods: one is multi-grade pure water filtration; another one is Ultrasonic clean-out.
9, Plating
At present, there are two methods. For Ni (Nickel) plating domes, generally factory purchase the material which already has Ni foil on the raw material. For Au (Gold), there are two ways: one is Au on raw material, another is manufacture metal domes without any foil firstly, then send them to electroplate workshop to have Au plating. Also it can divide into single side and two sided Au plating.
10, Usage of Metal Domes
Peter from Best Hardware Co., Ltd., believe that it is a future direction that more and more products which require click feeling, excellent electric capability, long life performance, better acclimatization will use metal domes or metal dome arrays (metal dome switches).
Right now it is widely used in communication electronics, home electric appliances, industry control equipments, medical machines, with the macroscopical view.
For more usage of metal domes in microcosmic view, please browse our website (http://www.metal-domes.com) to learn more. I hope right now everyone can understand the basic technology and parameter of metal domes in our industry.
If you still have any questions, or have different thought or views with us, or have some suggestion or comments, please leave your messages here or contact us.
Author: Peter
Published: Metal Domes Technology and Parameters; Metal Dome Blog
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