Frequently Asked Questions About Metal Domes

Q. Do you have local distributors in our area?

A. We do not use distributors. We ship worldwide by any shipping method you prefer. All of our products are manufactured entirely at our facility in Windsor, Colorado, U.S.A. Contact us to set up an account.

Q. How can I purchase metal domes from Snaptron?

A. All purchases are made directly from Snaptron. Snaptron offers a variety of ways to purchase metal domes. The most common way is by setting up Net 30 terms where we invoice you after a purchase is made. Snaptron also accepts major credit cards or payment in advance.

Q. How are the domes packaged?

A. There are several different packaging methods to choose from, depending on your specific application. The domes can be packaged in bulk (jars), in cartridges for use with the Dart™ placement pen and the SureShot™ automated dome placement machine, in pocketed reels for use with pick and place equipment, on polyester-adhesive sheets (Standard Peel-N-Place arrays or Custom Peel-N-Place arrays), and Peel-N-Place arrays in reel form.

Q. Can the domes be soldered to a circuit board?

A. Not recommended. When the domes are pushed, the feet actually move outward slightly. When soldered to a circuit board, the feet of the domes are restricted from their natural movement. This restriction can negatively affect the tactile response of the domes, and in some cases, cause irreparable damage to the domes or break the solder joint.

Q. How do I secure the metal domes to my PCB, membrane, or flex circuit?

A. Our metal domes are secured by means of pressure-sensitive adhesive tape. Several standard material options are available, as well as custom materials. See our Peel-N-Place Arrays for more information on placing the domes with tape.

Q. Can your domes be assembled with standard pick and place equipment?

A. Yes, Snaptron offers pocketed reel packaging for use with automated placement equipment. We also have dome arrays in reel form, which can be placed by fully automated label placement equipment. Please contact us for more information regarding automated dome placement equipment.

Q. What does trip force (Fmax), release force (Fmin), and tactile ratio of a dome mean?

A. Actuation force, or trip force, is the amount of force that is necessary for the dome to “snap”, changing the dome from the open position to the closed position. Typical actuation forces range from 40 grams, to 2,250 grams or higher depending on the size. Snaptron measures actuation force in grams. The release force is the amount of force the dome exerts on itself to return to its relaxed state.The combination of actuation force and release force gives you the tactile ratio for a dome. The higher the tactile ratio, the “crisper” a dome feels when actuated. Snaptron U-Series domes are specifically designed with high tactile ratio. A tactile ratio that is too high may affect the life of a dome in certain applications.

Tactile ratio = (Fmax – Fmin) / Fmax x 100

Q. What does it mean to over-travel a metal dome?

A. Actuating the dome past its designed travel. For most domes, this is beyond the flat plane of the foot. Domes can be designed to over-travel (see M-Series)

Q. Is there a recommended actuator for depressing the domes?

A. While there are any number of different sizes and shapes of actuators, we test the actuation force of our domes with a .050 diameter, flat-bottom plunger. See Test Procedures for more information on testing the domes.  We recommend that your actuator size is no more than 25% of the dome size.  Anything larger has the potential to damage the dome.

Q. Is venting required for optimal dome performance?

A. While venting is not absolutely necessary for every application, it is desirable in almost all applications. When the dome is depressed, air is trapped underneath it. To avoid compressing the air under the dome when actuated, it is recommended that a vent channel be present. The venting of the dome can be achieved a number of different ways. Some examples: a.) vent channel can go from dome to dome via a spacer layer b.) dome arrays can be top vented through the polyester material c.) vent channel can go through the board. Not properly venting the dome will result in significant loss of tactile response.

Q. What is the purpose of a dimple in the center of a dome?

A. Various Snaptron domes have a dimple located in the center of the dome. Typical depth of the dimple is .001” to .002” but may vary depending on the dome style. A dimple is used to reinforce or improve the dome contact with the PCB.

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