Metal Domes « Metal-Dome

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Why Metal Dome Force Changed After Assembly on PCB

Friday, May 4th, 2012

Recently one customer complain that the metal dome force changed so much after assembly on PCB.

The metal dome used was “X6T-350-0.8*3.0”(A Triangle dome, Diameter 6mm, force 350gf, leg: 0.8*3.0mm). Before assembly, force is in normal force range 350gf, but after assembly on PCB, force change to about 500gf and then make whole dome key hard to press.

After saw customer’s PCB samples, we understand why this happened.

What method used was method A we recommend in “How to Assemble Triangle series metal domes on PCB (2)” (Please click to see more details for that article: http://www.metal-domes.com/blog/2010/07/02/assemble-triangle-metal-dome-on-pcb-2/)

Method is okay, but the problem was related with PCB design of customer. For Diameter 6mm triangle metal dome, the distance between two legs is 6.0mm, tolerance +/-0.2mm, so the tooling hole on PCB should be designed following that value.

6mm Triangle metal dome

But when we measure the PCB, the distance between holes on PCB is only5.35mm. You can see a picture bellowing.

PCB Hole Distance

Because hole distance on PCB is too narrow, so it’s difficult to insert leg of metal dome into the PCB. You can see when put metal dome on the PCB holes, it will not go into the holes, but remain above the PCB.

When you press metal dome and leg can be inserted into the hole, but only one leg is properly installed, another one was shifted. You can see the red arrow.

Wrong PCB Hole Distance

When press metal dome, people have to add extra force to bend the edge metal dome toward to center, to make the diameter from current6.0mmto5.35mm, so that end of metal dome leg will be on the same level of PCB. That extra force will be at least 150gf, so final metal dome force become 500gf (350gf+150gf). This is the reason why metal dome force altered so much between before and after assembly.

After realizing the problem, customer re-designs PCB and problem solved. Metal dome force keeps the same before and after assembly on PCB.

Just remember to have the same hole distance like metal dome diameter. If dome used is6mm, then distance6.0mm, for8mm, use8.0mmhole distance.

If you are not sure about that, please contact us before you design the PCB. We will be glad to provide service.

Tags: metal dome assembly, triangle metal dome
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Metal Dome in Tube

Monday, September 26th, 2011

Regarding the Four-leg metal domes, for small-medium volume production,
if people want a high assembly speed, but don’t have Automated SMT machine, we recommend us our metal dome in tube, as well as Peel & Place dome. And here, I’d like to say more words about metal dome in tube. Next article we will discuss another.

To use metal dome in tube, you must have a dome placement pen, or auto-pick-gun. You insert the tube into that device, then move the device above the place where you want to place a metal dome, then push a button, a dome will come out, to fall on that position.

Using tube dome, you only need to push the button to place the metal dome, and don’t need to pick a dome by a tweezers, so it’ll make dome placing become a easy job. You can put about 1,000-2,000 pcs per hour. In fact, some expert guy can reach up to 3,000 pcs, 5,000 pcs or more.

Also if you can send back the empty tube to us, we will give you some discount, but in most case, oversea customers will not do that, because shipping fee is more expensive than tube itself. But I think if some days later, the cost of tube increased and shipping cost lower down, people will consider to re-use them, in a green way. Just make sure the tube is clear, fresh from any dirt, dust.

All right, leave comments if you like this, or have some comments, or better idea to improve the tube metal dome.

Tags: Four Legs Metal Dome, metal dome in tube, metal dome packing, tube metal dome
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Four-Leg Dome with Legs

Tuesday, July 5th, 2011

As we know, there’re already four legs for our Four-leg series metal dome, and this is why it named four-leg dome, or cross metal dome. So what do you means “four-leg dome with legs”?

Let me firstly see the looking of a normal four-leg (Cross) metal dome.

Normal four leg metal dome

We can see there’s no extra legs except these four legs which will be put on contact PAD of PCB, FPC, or membrane.

As we don’t recommend soldering metal domes on the board, so how do I adhere the dome, except normal “dome array“, “single key dome array“, or in the socket? Can I fix it on like triangle metal dome using two legs insert into the board hole? That’s the reason whey there’re extra legs for F series (cross) dome. You can see pictures.

four-leg dome with legs

Now is everything clear? There’re two extra leg, and you can insert the into the holes of board like triangle metal dome do. Currently on our Dia 11.4mm four-leg dome, these extra legs length is 1.2mm and width 0.9mm.

If you need more information about this special four-leg (Cross) dome with legs, contact BEST and we will give details to you. We can also make new tooling to make new diameter four-leg metal domes.

Tags: Four Legs Metal Dome, metal dome, metal dome assembly
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Circle Metal Dome with Leg

Sunday, June 5th, 2011

Previous we have discuss how to assemble triangle metal dome, some people told me they also want a circle dome with a leg. But for most of circle (round) series metal dome, there’s no leg.

So when assemble with a circle metal dome dome, you need to put it on a printed circuit board, or a flex circuit, by a adhesive tape, or put it in a socket.

For 1st method, you can use our “standard single key dome array“; for 2nd way, just buy dome in bulk. it’s easy, but if you also want to fix circle dome in the socket, then you will hope this circle dome with a leg. Am I right? Hooo, dream comes true. Here are some pictures for them.

Circle dome with leg details 1

circle dome with leg details 2

Currently, there’re few circle domes has leg, because this kind of requirement can be replaced by triangle dome. So now only Diameter 5mm is available in the market now. Force 160gf, 180gf are standard, 130gf and 200gf also no problem to be made.

If you need other legged circle metal dome, we can set up new tooling to make the special dome. Contact BEST if you interest in this circle metal dome with leg.

Tags: circle metal dome, metal dome, metal dome assembly, round metal dome
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How to Assemble Triangle Series Metal Dome on PCB (2)

Friday, July 2nd, 2010

See previous article here: How to Assemble Triangle Series Metal Dome on PCB

Question # 2: If soldering triangle dome is not recommended, then is there any better method to fix it?

Best Tech Answer:Of course. There’re three methods to make it:

A) For the triangle metal dome with leg, you can insert the leg directly to the PCB, and then curve the leg at back side, make sure it could buckle the PCB. That’s the common way.

Triangle metal dome with leg on PCB

But to be noted that the assembly speed is slow. So you need to calculate how much you need to pay for extra human handling fee.

To have two location holes on the PCB and choose the different leg length in accordance with thickness of PCB are two important things should be considered during your design.

PCB with triangle metal dome

Normally thickness of PCB which will use triangle metal dome are 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 2.0mm, and the leg length of our triangle metal dome are 0.8mm, 1.5mm, 3.0mm, and a special one: 2.4mm. You need to choose a longer leg to insert into PCB and bend it. For examples, if you use 1.6mm dome, then our 3.0mm leg will be fine.

B) Directly using the adhesive tape to stick on the metal dome on PCB.

It will save little time compare with insert leg into hole of PCB (method 1).

But the stickiness of common transparent adhesive tape is not so well, metal dome was intended to be shifted or peeled off.

Also thickness of adhesive tape is too thin compare with height of metal dome, it’ll cause uneven of whole products, and too many bubble between PCB and adhesive tape.

C) Using metal dome array.

Triangle metal dome array on PCB

This is the most convenient and precision assembly method. Although the price is a little higher than other two methods mentioned before, but you will save a lot of time on inserting leg into hole of PCB or put adhesive tape on PCB, you only need to peel off dome array from liner paper and put whole products on PCB. In a word, this will increase assembly efficiency, precision (avoid potential alignment problem), and then reduce whole price.

According to different request of clicking feeling, you could use circle/triangle/four leg metal dome. If you want to get more information, please kindly visit our website for reference: http://www.metal-domes.com/cn/product-dome-array.htm

Ok, my friend, now do you have a idea to design and assemble your PCB with triangle metal dome? J

Let me know if you want to know more information on installing triangle metal dome, I will be happy to answer you anytime. We, Best Technology, are always be your best partner in metal dome and metal dome array in China.

Tags: metal dome, metal dome array, metal dome assembly, PCB, triangle metal dome
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Archive for the ‘Metal Domes’ Category

Four-Leg Dome with Legs

Circle Metal Dome with Leg

How to Assemble Triangle Series Metal Dome on PCB (2)

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