Metal-Dome

Not everybogy knows everything, so does the purchasing of metal domes. I have got many enquiries about metal domes, but necessary information was missed, so I need to ask for that. The top quesionts which I asked for are as follows:

1) Shape
    Of course we need to know the shape of metal domes. It’s the initial step to decide what kind of metal dome is. Right now, we have four basic shapes, namely: Circle, Four-Legs(Cross), Triangle and Oblong. For more, please check: Metal Domes (http://www.metal-domes.com/products.htm)

 2) Diameter
     The diameter decide the size of metal domes. But the measure point of different metal dome is different, that is the starting point and the ending point is different. Today, I will discuss majorly about Four-Legs(Cross) series.

Firstly, look at following picture showing the metal domes with different diameters.

                           (F-series-metal-dome-with-dimple)

Then let me check how to measure the diameter of F series metal dome, using a vernier caliper.

Now, you can check the figure is 12.2mm, and this means the diameter of that dome is 12.2mm.  Yeah, absolutely right. Let’s exlain it by CAD Drawing. It’ll be more helpful for you to understand that.

Does it make a sense now?

3) Height and travel of metal dome

You will note from the above picture that how to measure the height and travel of metal dome. In fact, we have discussed this issue before. You can browse this article to get more parameters of metal dome: Metal Dome Technology and Parameters: http://www.metal-domes.com/blog/2006/11/11/metal-dome-tech-and-parameter

I hope you’ll understand what you will need after view the above. If you still have questions, please feel free to contact us.

In next article, we will talk about how to measure other metal domes with different shape.

(to be continue…)

We have posted an article name:Function of Dimple in Metal Dome Oct 18 to discuss function of dimple of metal dome. In that article, we ask our visit to talk about it, and received several emails. Thanks for everybody whom involved in that case. Today we’ll make a short conclusion regarding the dimple of metal dome.

First of all, we should know that all T (Triangle) series metal domes have dimples. So it’s a optional part for other three types of domes: C (Circle), F (4-Legs), O (Oblong) and Custom Designs.

Then let’s talk about its funtion as follows:

1) Increase the Travel (Stroke)

2) Increas the Contact Areas and Enhance the Stability of metal dome

When you press the dome and release it, the dimples can increase the contact areas on PCB, as well as other function, so it can enhance the stability. You can check this article New Circle Metal Domes to know our lastest new large dimple of domes.

3) Dust Resistance

If you want to know the details of this, don’t hesitate to contact us, we’ll send you more information.

Although we’ve said in the main products page of metal dome how it works, but without the assistance of visible picture, many person still don’t know its theory. Today I draw a simple sketch, help it can be helpful for friends to understand it.

While you research the picture, you can write our instruction of how metal dome works in metal domes, namely “They function in the following way: The metal domes are placed on the printed circuit board by means of pressure-sensitive adhesive tape. In their relaxed state, the metal domes rest on the outer rim of the primary pathway. When pushed, the domes collapse and make contact with the secondary pathway, thereby closing the circuit. ”

To know what a metal dome  is, maybe this article, Metal Dome VS Steel Dome,  can help you. Also the artiles in metal domes  maybe be helpful for you to learn more the metal dome (sometimes people call it metal snap domes) . 

Do you understand it now? Or think about the other things need to provide to enrich this explanation? Leave your response here!

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’s a CP or CL is, how’s the plating, and so on. Today, I’ll 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’s 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’s 1 out 1, for the normal factory of metal domes.

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%.

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’re basic four types: Circle (Round), Four-Legs (Cross), Triangle and Oblong. Also customers’ design is welcome.

8, Handling of Smudge

Cleanout: There’re two methods: one is multi-grade pure water filtration; another one is Ultrasonic cleanout. 
9, Plating

At present, there’re two methods. For Ni (Nickel) plating domes, generally factory purchase the material which already has Ni foil on the raw material. For Au (Gold), it’s 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’s 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’s 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
All right reserved. Be reproduced in the form of annotated links to the original source and author, and this statement.

Have you seen that picture? Do you know the name of four “dot” in the pictures, one in middle, three in peripheral?

Haha, maybe you already know it, maybe not. The name is “Dimple” in the metal dome industry. It’s a important parts of metal dome, though it’s a little small.

Do you know what’s the usage of that small dimple? And how important it is? You can tell me your answer, send email or leave your comments via this blog. I’ll release the answer in the coming day.

We call it “Dimple”,

As you know, the product lines of metal domes which is popular used currently are from 3mm to 12mm, whether the shape is circle, four-legs, triangle, or oblong. In fact, different shapes of metal domes have its own advantage and so do the product ranges. For examples, the most popular diameter of circule metal domes is from 3mm to 10mm, sometimes, 12mm. And if you need the larger diameter, you’d better consider to use the Cross metal domes or Triangle metal domes.  Why we reommend them?

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As we mention in our products metal dome arrays - EMI printing, on top of the Mayler which carries metal dome contacts, silver paste or silver carbon paste is printed as ESD (Electrostatic Discharge Control). In fact, not only we use ESD in metal dome arrays, but also other products need it, it’s such a important accessories that it can be found in most cases of all high precision end products, such as the Cell Phones, electronic transmitters, and so on. Now let’s take a brief glance at the following words to unveil it 

ESD

(Electrostatic Discharge) is the term used to describe the sensitivity of electronics components to static electrical charges. (more…)

 For the previous article, please view http://www.metal-domes.com/blog/2006/09/08/stainless-steel-material-of-metal-dome-1 

4) Families of stainless steels

There are several families of stainless steel: FERRITIC, MARTENSITIC, AUSTENITIC and DUPLEX. These names are derived from the crystal structure of the steels, which governs their metallurgical behaviour.

FERRITIC stainless steels are magnetic, have a low carbon content and contain chromium as the main alloying element, typically between 13% and 17%.They are not hardenable by heat treatment.

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As you know, the raw material of metal domes (or named snap domes) is stainless steel. (Sometimes the phosphor bronze are used, but much seldom). The quality of material will affect the quality of finished metal domes, so we must be much careful in purchasing stainless steel. Now let’s take a brief glance at the information about stainless steel, hope it’ll be useful for you to understand it and helpful in others. You are also welcomed to provie the supplements about it. Leave your response or send us an email.

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