What’s light guild film and what function of it?

Posted on September 24, 2021 by Love Dome

LGF, also known as light guide film , is a new product designed to improve the existing light guide film. It is to add a layer of LGF to the current common double layer metal dome structure, so as to achieve good light distribution effect.

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double layer metal dome structure

Using LGF( light guide film) on PCB (print circuit board), such as POS machine light source only need 1-4 LED lights, the use of light reflection and refraction principle, combined with special optical software design, do microstructure processing on the fiber film, so that the “point light source” expanded to “surface light source”.The beam propagates from the medium at the right Angle and density, so as to achieve the excellent effect of uniform softness and high brightness.

LGF dome array

Various parameters and advantages of light guide film (LGF) are as follows:

  1. Light guide film (LGF) has two types material: PC and PU; Both materials have the same light guiding effect; Comparatively speaking, PU material is softer and feels better. And PC material in the price advantage.

2. LGF thickness of light guide film has two kinds: 0.125mm and 0.1mm, both of which are the same. Thick light guide film has good light guide effect, strong light spot and concentrated light.And the light guide film of thin point has the advantage on feel.

3. Good luminous effect, uniform brightness, high light intensity.

4. Light, soft, thin thickness.In the use of mobile phones, different from the light guide plate takes up a large space.

5. Save LED qty, save power consumption, save cost.

6. Simple structure, does not affect the overall product design (does not affect the click sound of metal dome) and feel good.

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What’s caused the poor click feeling when pressing metal dome?

Posted on September 22, 2021 by Love Dome

The click feeling of metal dome is very important for the using of whole product, a good click feeling not only need the metal dome has very good click feeling, but also related with the assembly of whole product, if you find a product with poor click feeling, you might analyze from below aspects:

  1. Click feeling of the metal dome is not good, we can test the metal dome by load curve tester and get the test result for height, force and rebound force, when the height is too low or rebound force is too high, it’s easy to cause bad click feeling. For this aspect, we can improve the click feeling by adjusting the height or rebound of the metal dome.
Dome array assembled with another overlay
  • Whether the silicon button which contacted with metal dome is too big? If this silicon botton is too large it will also affect the metal dome’s click feeling. For this problem we can improve the click feeling by reduce the diameter of silicon button.
dome array with silicon button
  • Whether the space between silicon button and PCB board is appropriate? The space too large or too small will both affect the press feeling.
  • Metal dome assembly deviation. Usually the metal dome was assembled on PCB borad by manual, so there is some deviation, and large deviation will cause bad click feeling. For this problem, we suggest to make assembly by jig and located position to reduce the deviation and improve click feeling.
  • There is another condition that some clients may put another coverlay on the surface of metal dome after assembly, if the coverlay is too thick then it will affect the click feeling as well.
Curve test performance

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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What factors will influence the click feeling of the metal dome after assembly on PCB

Posted on August 19, 2021 by Love Dome

We always get feedback from customers that the click of dome switch or metal dome is not good after assembly on PCB, what reasons cause this issue? That’s what they care about most. Today I will analyze it from the following reasons.

  1. There is an 0.15mm assembly tolerance when assemble metal dome onto PET adhesive
  • If place four legs or triangle metal dome, there will also be a 5 percent angular tilt tolerance.
  • If place round metal dome, the diameter of hole on spacer would be 0.3mm larger than metal dome, then could ensure unilateral tolerance of 0.15mm
  • There is a assembly tolerance when customer place dome array on PCB (print circuit board)
  • The press key or press rubber key is very large, exceed 30% of contact surface of metal dome from center, lead to hard to press and influence the click.

All above factors would influence the click of snap dome, so we need to take these factors into account when we produce. Avoid trouble in next step.

If you still have any question after read, please feel free to contact us, we are here always and would solve your issue and provide our help to you.

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New product launch in line

Posted on August 18, 2021 by Love Dome

Good news, we developed and new prouct and lauched in line now! An special square metal dome with Ø 3.0 hole in center,  which allow you place an LED on the PCB board directly. The dome dimension is 7.4*7.4mm, standard trip force from 220gf to 350gf, 0.1mm SUS301 material. Except the standard stainless steel product, nickel plated or gold plated both optional.

Technical drawing

This unique square metal dome is durable and reliable while maintianing good click feeling. There are four “ball shape” leg in all four corners to enhance the contuctivity between metal dome and PCB board.  

Product picture
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What problem or issue would have if the metal dome height and PET adhesive size are not suitable?

Posted on July 16, 2021 by Love Dome

Recently, we got feedback fron one of our customers that found Plastic of Dome Switch bulge and peel off as below photo when production after assembly dome array on PCB, we could see the place from the red arrow. Why will have such issue happened? See the following analysis.

PCB with dome array

This is due to the product design flaws, it’s not the problem of the PET adhesive, two reasons below that lead to this issue:

  1. The height of dome switch that used is around 0.75-0.80mm, it’s very high height.
  2. The adhesive tape area from metal dome to edge is only 0.40-0.60mm, you could see from above photo, and only cover a layer of PET with 0.05mm glue, viscous tension is not enough to support for a long time; It will inevitably jack up the material with such high dome height.

We can use the schematic diagram below to understand above issue. If we want to achieve the ideal, we need to use the right height of snap domel and the suitable adhesive tape size. If we want to solve this issue above, we could do below based on the actual situation:

  1. Drecease the height of metal dome, keep original adhesive tape size.
  2. Increase the adhesive tape size, keep the original height of metal dome
  3. Drecease the height of metal dome and Increase the adhesive tape size.
structure analysis
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What the difference between metal dome with dimple and without dimple?

Posted on July 16, 2021 by Love Dome

We had knew that metal dome has different types, without dimple and with one or several dimples, but do you know what the difference between with dimple and without dimple?

the metal dome without dimple

The biggest difference is the difference in conduction stability, the metal dome with dimple has better conduction stability than no dimple metal dome.

Because in the using process, once there are dust on the contact side of metal dome, the no dimple metal dome is surface-surface contacting with PCB pad, and the dust will block the conduction.

the metal dome with dimple

For the metal dome with dimple, there are dimple to surface contact with PCB pad, as long as the dust didn’t exsit on the dimple, it will not affect the conduction, even the dust is on the dimple as long as you press the dome several times the dust will fall off. So the conduction stability is more better.

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 improve the metal dome assembly efficienc?

Posted on June 19, 2021 by Love Dome

As the labor cost increase every year, more and more customer pursue the assembly efficiency of metal dome. So how to increase the assembly efficiency?

There are many methods for metal dome assembly, such as the triangle with legs is fixed with the pin hole of the boards, for this kind metal dome we need manually place the dome one by one, the assembly efficiency is very low, cost many labor.

triangle-metal-dome-insert-in-PCB

And some customer might manually place the metal dome on PCB boards one by one and then stick adhesive tape to fix the dome with PCB board, although save material cost but this methold also has the disatvantage of low assembly efficiency and high labor cost.

stick-adhesive-tape-to-fix-the-dome-with-PCB-board

Currently the most popular assembly method is customorize a dome array according customer’s PCB boards, put several kinds metal dome or several quantity metal dome on one dome array sheet, customers only need to stick a board one times. Not only the assembly efficiency increased and saved labor cost but also improved the functional stability.

dome-array-with-many-metal-domes

Furthermore, if you want improve the assembly efficiency on the basis of this method, we can design the layout of dome array sheet according customer’s PCB panel layout, put several or dozens dome array in an specific layout thus we can assemble several or dozens dome array on PCB boards at one time, this method can greatly increase the assembly efficiencyof metal dome.

dome-array-with-many-different-metal-domes

In addition, we have other method to improve the assemble effiency, such as make many dome sheets in one entire sheet according the PCB panle and then assemble the entire sheet on PCB panel at one time. More details you can refer to another blog

How to assemble entire sheet dome array on PCB panel at one time?

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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What’s air vent hole and function of it on dome array?

Posted on June 16, 2021 by Love Dome

The hole on PET around metal dome or the slot between dome and dome is called the “vent hole” or “vent slot”, which is very important for the normal operation of metal dome. It will result in poor feel and affect the function of the switch if without the vent hole. Although this design may not be used in every applicable product, it is desirable in almost all applications. When you press on metal dome, the air is trapped underneath it. So when we press on snap dome, in order to prevent the air from being compressed underneath, we have to make a vent slot for dome switch.

There are different ways to make vent holes of dome array, for example:

  1. the vent holes can be designed between metal dome and the spacer;
Dome array
  • A small opening hole can be made on the top layer of dome retainer;
Dome array drawing

pcb

In a word, the improper design of the vent hole of Dome array will seriously affect the feel of metal dome when pressed. Please pay attention for this issue.

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Can metal dome be weld on PCB board?

Posted on May 14, 2021 by Love Dome

We know there are different assembly methods for metal dome, such as metal dome with legs can insert in PCB’s pin hole to fix, similar like below picture. Most of the dome switch with legs are triangle type. It has several leg specifiication: 0.8*0.8mm, 0.8*1.5mm and 0.8*3.0mm. Usually we can choose the metal dome with the appropriate leg length according to the PCB’S thickness. If you want know further information about how to assemble it please refer to another article “How to assembly triangle series metal dome on PCB”.

triangle metal dome insert in pcb
triangle metal dome with different size legs pcb

Another method is making metal dome with adhesive tape to be dome array and stick on PCB to conduct with it, we also call it as dome sheet, peel dome. The advantage of making dome array is that its assembly efficiency will be faster than insert one by one, especially when the number of metal domes on a dome array is relatively large, and one dome array can contain different types metal dome but only assemble one time.

dome array with many different metal domes pcb

Beside those two methods, some clients chose to weld metal dome on PCB board directly, normally we don’t suggest to do it so . Because the metal dome has a little arc with a certain ductility, when we pressing it the metal dome will extend around, if welding it on PCB board, the metal dome can’t extend around when you pressing it, as we pressing for a long time it will easily cause the metal dome to be concave, so it is not recommended to weld metal dome directly.

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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Can metal dome sheet go through high temperature furnace?

Posted on May 14, 2021 by Love Dome

Some customers could ask whether metal dome array or dome sheet can pass high temperature furnace? The answer is no.

Why some customers would have such a request? That’s because they need to do the welding and soldering process after place the dome switch into the print circuit board, thus they need to go over a high temperature stove. But the maximum temperature of the PET adhesive material can withstand is around 125 degrees (suitable working temperature is around 60-80 degrees), and the temperature in a high-temperature furnace is more than 200 degrees. The material melts when it enters a high temperature furnace, so it’s definitely not going to work.

If the customer must do as that, then need to change to use a material that can withstand high temperatures. However, there are many improvements in the difficulty of the production process and the cost of materials is very high. Therefore, we will suggest that the customers assemble the dome array 

after welding the high-temperature furnace, which is very reasonable and convenient.

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