How to increase the click feeling of metal dome?

We know the click feeling of metal dome largely affects the use of the whole products, so how should we do to improve the click feeling of metal dome?

Here are the answers:

  1. Choose the high-height metal dome, such as four leg metal dome, metal dome with dimple on center or metal dome with dimple on side. Their has relatively strong touch feeling itself, can remian better click feeling after assembly.
  • Adjust the click ratio directly. We know click feeling (CC) has a equation to define: CC(%)=(CP-CL)/CP*100%, the higher the CC score, the better click feeling. But we don’t suggest to make CC score exceed 70%, because if the click feeling is too high then it will affect the life cycle of snap dome.
  • Make UV plunger on the surface of dome array, position on the center of switch dome to improve the click ratio, this kind products we called UV plunger dome array.
  • Don’t make thecontact silicon botton too large, large silicon botton will affect the click feeling as well.
  • Make the dome array accurately aligned with PCB pad during assembly. Becasue the click feeling in center of metal dome is the best, the deviation will also affect the click feeling.

Best Technology, as the top 5 metal dome & dome array manufacturer in China, we have more than 15 years experience in snap dome, metal dome sheet and tactile membrane switch industrial, our metal dome is equivalent with Snaptron & Nicomatic metal dome,we can always provide you the best solution for your dome switch project. If you have any doubt or inquiry about the snap dome please kindly call us or email us at any time.

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Why need to add an plunger (actuator) on metal dome array?

Why the customer want to make an plunger or actuator  on the top layer of metal dome array?

There are two main functions:

1. Increase the total height of overall product;

2. Increase the touch and click feeling of dome switch.

The height and diameter of the plunger or actuator should be based on the diameter of the tactile dome, and need to make a tooling for plunger making.

But at the same time, we need to pay attention for below issues when making plunger or actuator.

  1. It’s better to make the height of plunger or actuator under 1mm, then the defect rate is very low.
  2. If the height of plunger is larger than 1.0mm, the defective rate will be 20% to 30% more than the usual 1mm.
  3. The poor performance is mainly a small bubble inside a, can be seen by visual.
  4. There are also some bubbles around edge, this will cause the plunger to fall off with a gap.
  • The plunger itself can not be straight, showing a cone, because the plunger plastic molding curing, need to be pulled out of the mold, there will be a drawing Angle. 
  • The plunger is made on the top layer (MYLAR or dome retainer) and then transferred to spacer, there will be tolerance.
  • In addition, the assembly of dome switch (metal dome) on PET adheisve also has tolerances, so Plunger and tactile swithch (metal dome) can not be completely concentric.
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What the reasons for poor conduction of metal dome?

We all know that the metal dome is very important for the conduction of electronic product, if the metal dome has problem, the whole product will be affected. Then whether a product has conduction problem and its must caused by the metal dome? Sure, it isn’t.

Let’s briefly introduce several situations of poor contact of metal domes.

  1. When there are some dirts on contact side of metal dome and PCB boards, they will all affect the normal conduction of metal dome.
pads with adhesive
metal dome with dirts
  • If the PCB pad layout is incorrect, its will affect the metal dome conduction as well. For example, if the external diameter of PCB pad is 5mm, but the snap dome size is 6mm, when pressing down the metal dome, it will exceed the pad and can’t connecting so it won’t work.

Normally we suggest that the external diameter of PCB pad should exceed at least 1mm than metal dome.

metal dome and pads
  • If your product has a silicon keypad and the gap between silicon keypad and PCB boards is too large then it will result poor conduction problem. As we are pressing the silicon kepad to make metal dome down to connect with PCB board, if the gap is too large we can’t make the dome down on PCB pad, then it’s no conduction.
  • If the deviation of metal dome assembly is too big that may also affect the conduction, because normally we press the center of metal dome to make product connected, if the assembly is deviated too much, when we press the center of product it may acutally working on the side of metal dome but not on the center, and that means the dome can’t down on the PCB pad to make conduction.
assemble deviation

Best Technology, as the top 5 metal dome & dome array manufacturer in China, we have more than 15 years experience in snap dome, metal dome sheet and tactile membrane switch industrial, our metal dome is equivalent with Snaptron & Nicomatic metal dome,we can always provide you the best solution for your dome switch project. If you have any doubt or inquiry about the snap dome please kindly call us or email us at any time.

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How to distinguish quickly the suface of Nickel plated, gold plated, silver plated, stainless steel, phosphor bronze silver plated from metal dome?

The color appearance of Nickel-plated and stainless steel is relatively indifference, so need to distinguish through the multimeter, adjusted the multimeter to the diode gear, the two pens moved on the metal dome at the same time, if the sound is continuous and crisp, it is nickel-plated, if it’s intermitten, then the surface is stainless steel.
The material is gold plated, silver plated, and phosphor bronze, which can be distinguished by appearance, gold plating is usually single plated, contact surface is gold. Silver plated is usually single side silver plated, contact surface is silver. And phosphor bronze is silver plated, the surface is copper, the contact surface is silver.

metal domes
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Can different shapes and size of metal domes be placed on a dome array?

Different metal dome shapes (four legs snap dome, triangle metal dome, round and oblong tactile dome) and diameter can be done on a dome array, we could do as the customer request. Why does the customer have such a request? The reasons as below:

  1. It may be the design problem of the customer’s circuit board.
  2. Different keys with different requirements, only use different domes, then could meet the requests. Such some keys require higher force, some keys require good click feeling;
  3. The size of the keys is different, so we have to use different diameters of metal domes.
    Although this kind of metal dome array can be made, the process of making is a little more complicated. It needs to make two or more laminate (assembly) fixtures and assemble them twice or more, it bases on the dome types. So the assembly time is twice or more as much as that of a single shape and specification, so the price will be higher.
    Recommendation: Use a shape and size of metal dome if no special requirements are required.
Plunger (actuator) dome array
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What performance should we learn about metal domes?

Do you know what is the force, rebound force and click ratio means in metal dome product?
Those are some basic performance we should know if you are going to buy metal dome, hereby we will tell you.

CP means compression peak force, we usually use it to define the operation force of metal dome, Its means the biggest force you pressed on the snap dome and make dome from a short opening status to the conductive status. CL means the compression low force, we also call it as rebound force. Its means the biggest force when the dome back from conductive status to opening status. Generally people use G(gram )or N (Newton force) to define all kinds force concepts. Please also refer to our blog how to test the life of metal dome .

Curve machine for force testing

And click ratio, someone also name it click feeling (CC) has a equation to define: CC(%)=(CP-CL)/CP*100%, this CC result(click ratio) is commonly required at 35%~6o%, if the click ratio is too high then it will affect the life cycle of metal dome. Briefly, you can also refer to the below chart to understand these concepts.

Fore test report for example
Best Technology, your best partner in Asia, is professional for dome sheet and dome switch more than 15 years in China. Please feel free to contact us if you have any question about snap dome.

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How to clean metal dome and what we should check after cleaned

The key point to determine the quality of metal dome and snap dome is that whether the metal dome is cleaned or not. If the metal dome switch is not cleaned, it will affect the conduction of circuit board, which causes a functional problem, so the process of cleaning is very important. The cleaning of metal dome is done by Ultrasonic, Steps as below:
1)Put unclean snap domes in box

2)Using a special chemical potion with about an hour of cleaning for tactile dome

3)Clean tactile dome by clean water after medicine cleaned

4)Drying metal dome for an hour

5)Taking out metal domes or snap dome from box and Loose packaging with bag.

If cleaning is not thorough, there may be laminated, rust and stains will be produced. So we need to check the appearance of metal domes carefully, such no scratch or crush on the surface and no deformation, spots, dirty.

Best Technology, your best partner in Asia, is professional for dome sheet and dome switch more than 15 years in China. Please feel free to contact us if you have any question about snap dome.

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How to make super large size dome array like 150*200mm?

As we already know there are two methods to manufacture metal dome array: laser-cutting or tooling produce . Usually when the dome sheet exceed than 150mm we will suggest to open a tooling to produce it. Is this the only way to make a snap dome array which dimension exceed 150mm? The answer is not.

Actually, for such super large size metal dome array (usually this super-sized dome array is more used on the keyboards), we have another method to do it beside tooling produce, especially when your demand quantity is not very large, consider from the perspective of cost saving we will suggest to make such dome sheet(also name dome cover) by laser-cutting. The precondition is we need dividing this super large dome array into several parts according the layout of metaldome, then we can produce those dome sheets by laser-cutting as supposed.

keyboards

Take an example for above PCB boards, the dimension is 212*161mm, except tooling produce we take another method as laser-cutting, we divided it into 3 parts accoridng the distribution of the snap domes( see the white frame line area in the PCB board), then those 3 dome arrays won’t exceed the range of laser machine, thus its very easy to produce the metal dome panel and save much cost as well.

dome array on keyboards

Although the assembly efficiency maybe a little bit slower than the whole sheet dome array assembly, but its does not matter, because we marked a white frame line on the circuit board, and we can also use it for alignment when assemble metal dome array on the PCB board, its very quick as well. For the assembly of dome array please visit our blog “How to Assemble Adhesive Tape of Metal Dome? “.

Best Technology, as the top 5 metal dome & dome array manufacturer in China, we have more than 15 years experience in snap dome, metal dome sheet and tactile membrane switch industrial, our metal dome is equivalent with Snaptron & Nicomatic metal dome,we can always provide you the best solution for your dome switch project. If you have any doubt or inquiry about the snap dome please kindly call us or email us at any time.

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Why dome array sometimes can’t be firmed very strongly?

We usually make metal dome array or dome sheet with the standard and normal tape (datasheet of PET adhesive ) . But sometimes we still would hear feedback from some customers that dome array can not be sticked firmly and strongly on PCB (print circuit board) or FPC (Flex PCB), see below photo. 

Specific reasons are analyzed as follows, wish it would be helpful for your product design..

  1. The dome film sheet made with high dome force and stroke (height) as the customer required, lead to the adhesive can’t be pasted well on board, because adhesive layer will be jacked up.
  • The adhesive tape area of snap dome array reserved and pasted in the customer’s drawings and specifications is not enough or too little. Generally keep a distance of at least 2.0mm above.

3. The viscosity tolerance of each batch of materials is different. If the material tolerance goes to the lower limit and the above two factors are added, the adhesion may not be very firm.

In general, our metal dome array is unlikely to have such a problem. For these special specifications, we can generally use a more viscous adheisve tape (such as 3M) to solve this problem. We have stronger adhesive materials for some special specifications of the snap dome sheet. However, there is a disadvantage is that it is not easy to tear after sticking, so you should stick to a good position at one time.

Best Technology, your best partner in Asia, is professional for dome sheet and dome switch in China. Please feel free to contact us if you have any question about snap dome.

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How to make dome array by laser and machine (1)?

Many people think that the production of metal dome array is very complicated, in fact it’s not. It’s easy to produce and the cost is not very high. Let me take you through the production process of metal dome array.

As all know, we need to control the production environment of our products well, so before we enter the workshop, we must put on dustproof overcoat, cap and shoe covers, and then be dusted by dust removal system in a closed room.

dustproof overcoat

Firstly, we need to do incoming inspection, raw material of PET adheisve with width, thickness, appearance and tension and metal domes switch with life times , force, diameter, height, burr, resistance and appearance, in order to make sure the snaptron domes are all same standard and meet customers’ requirements.

PET paper

There’re many kinds of PET paper with different colors, such as white, transparent, black, gold, etc. The gold one is most expensive and few customer use it. We often use transparent and white adhesive.      

PET paper

There are two methods to make snap dome array, one method is by laser-cutting, that produce with small qty, a litter longer lead time and higher unit cost, but could save tooling cost; And another method is by machine with tooling, that we can produce big quantities and save manufacturing cost in this way, but the customer need to pay tooling fee.

laser cutting machine with tooling

Now please let me briefly describe the process of how to make dome array by laser cutting. Laser cutting, the temperature of its operation can be 500 degrees. The cost for this manufacture is lower, but the processing charges is a little bit higher.

Firstly, we need to laser cut spacer hole (dome hole)

laser cutting

Second, do first article inspection. Put dome array on assembly Jig, check whether the snap dome hole on assembly Jig and spacer hole on spacer overlap.  

assembly Jig

Third, we can place other materials on the top of spacer to meet customers’ requirement after spacer production is finished, such place mylar, silver paste, rubber glue or LGF layer. No fingerprints are allowed to be on the spacer, so we’ll gently scrub the spacer by alcohol, and we can have pony-size spacer after machine cutting.

Coverlayer machine

After that, we need to laser cut outline and air channel.

laser cut

And then, Dimensional measurement for this dome array.

Dimensional measurement

After measure the size of dome array, we’ll assemble the metal domes switch on spacer by fixture.

fixture

There are dots on fixture, when the fixture is operating, we will put the snaptron domes on it, and the dots will fix the metal domes on them. Put the spacer (sticky side) on the top of Snap domes in dots until all the metal domes switch adhere to it. This is what metal dome array first looks like.

fixture

Afeter assemble sanptron dome on array, we need to check whether have double metal domes. Normally we use magnet to check it, will put metal dome array on powerful magnet, if there’s needless Snap dome, it can be attracted away by magnet.

magnet

Or use Electrical measuring fixture to check double metal dome, but the customer need to pay the fixture cost by themselves.

Electrical measuring fixture

After check the doubel metal dome, we’ll settle release paper on metal dome array. Finally we need to do finished product inspection and Pack & Shipping.

Pack & Shipping

Do you know how to make dome array by laser now after reading this article? Please feel free to contact us if you have any question. And I will introduce how to make dome array by machine in next article, please pay attention for us always.

Best Technology is your best partner in Asia, we are always here and waiting for your coming warmly.

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