If it is the first time you try to use metal dome or metal dome array on circuit board (PCB or FPC), then probably you want to know what kind of surface finishing of circuit board should be used if metal dome will be assembled on.
Basically there’re two types of surface finishing can be chosen: Gold (immersion or plating) and HASL (Tin). In most of time, we suggest using Gold. Why?
As you know, function of metal dome or metal dome arrayis to act like a switch, to make circuit to be closed or opened. And low contact resistance will be helpful for smooth, stable currency. All of us know Gold bas much better performance than Tin on electric conductivity. This is why we recommend Gold.
Whatever metal dome will be assembled on Rigid PCB, or flex circuit, gold is primary choice. Here are some pictures.
But when you need lower price, does not need strict stable currency or don’t care too much on switch on/off time, and then you can choose HAL (Tin). For most of circuit board used in ESU pencil are of HAL (LF). Here are pictures.
I hope above is clear for everybody. If still have question, leave your comments or send an email, we will reply very soon.