A variety of plating options are available depending on your specific application. Plating may vary depending on your requirements (life, contact resistance, etc).
Contact Snaptron with questions about plating in your specific applications. As a general guideline, Snaptron recommends the following:
Recommended PCB Plating for Dome Applications
(Proper plating is essential to prevent deterioration of the circuit pad over time)
Electro-Deposited Nickel, Bright Hard
<1,000,000 cycle life: 0.00005” – 0.0002” thick (50-200 micro inches or 1.25 – 5.0 microns)
>1,000,000 cycles life: 0.0002” – 0.0005” thick (200-500 micro inches or 5.0 – 12.5 microns)
Electro-Deposited Gold, Hard (Ref – MIL-G-45204C, Type II, Grade C)
<1,000,000 cycles life: 0.000015” – 0.00003” thick (15 – 30 micro inches or 0.38 – 0.76 microns)
>1,000,000 cycles life: 0.00003” – 0.00005” thick (30 – 50 micro inches or 0.76 – 1.27 microns)
Electroless Nickel/Immersion Gold (ENIG) (Ref – IPC-4552)
For lower life-cycle applications (contact Snaptron for more information)
Recommendations for plating are based on upon maintaining a stable electrical contact closure.
The movement of air is called “venting” and is important so that the dome functions properly. Lack of venting can cause adverse affects on the feel and function of the switch. 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.
Contact Snaptron for more information about venting.
Actuators / Plungers
Snaptron recommends a flat bottom actuator where applicable. The actuator (plunger) should be no more than 25% of the dome diameter. Actuators should always be placed at the center of the dome.