Low profile switches with protection ring?

Hello Folks,

For a project I am looking at switches. Digikey and the others don't seem to have the right kind. What I need is a momentary push button switch but in a way like they are done on Dell laptops:

• About 1/3" to 1/2" diameter.

• A bit recessed below a rim to prevent accidental touching.

• Very shallow profile, just a few 1/10th".

• preferably SMT gull wing mount, but doesn't have to be.

• Dirt cheap (of course...). 30c/10000qty or so.

It's basically going to be the on/off switch for a portable device where electronics do the actual switching. Accidental touching is an issue as people may throw the unit into a suitcase or pocket. They don't want to arrive somewhere only to find out it had turned itself on and depleted the battery. The uC can be somewhat nifty in detecting an 'erratic enough' push pattern to block unwanted turn-on. But that will have its limits so ideally there should be a ring around it that prevents something like a book to lean on the switch.

Regards, Joerg

Hello ZWS,

Not really. We have to start with machined housings, probably a Pactec ABS enclosure. Ideal would be a switch with a ring. Or a tact switch that is flat and that would be recessed far enough so the rim of the machined hole would act as enough of a ring. Problem with the latter is that most of those tact switches have just a tiny touch area. If there was one with a very low profile and a 1/2" or 1/3" round button area built in that might work.

Regards, Joerg

How much can you invest in designing this thing? If you're talking about the item being thrown into a book bag, how about a slide switch? If you only have a few hundred thousandths of an inch ( 3 mm? 5 mm? 7 mm?), you might have to invent something, but if so, my services are available. :-)

Good Luck! Rich

Hello Rich,

Pretty much nothing, We just want to buy them. There is enough custom design in this thing as it is.

I have found those to be notoriously unreliable. Even the one on my trusty TI SR-50 gave up :-(

More like 3mm. There are tact switches from Panasonic and others that cost less than 30c. The only issue with them is that their touch surface is too small. IOW if they wouldn't stick above the enclosure face panel (they can't because then the accidental touch protection would be gone) a normal finger could not reach.

Regards, Joerg

Joerg, I've seen soft plastic / rubber caps that fit into a simple circular hole in the enclosure. A SMD tact switch is positioned behind the cap. They need a definite finger tip press to actuate. They are similar to those on some car remote locking or immobiliser units. I've seen them in catalogues but cannot remember where.

The companies that make the "key fob" cases may sell them as an accessory.

Not as pretty as what you describe, but it would have the required function and might be ok.

May be something at:

Perhaps you could use an embossed flex membrane similar to described at:

r.

"Joerg" a écrit dans le message de news:I1Tyf.3297$ snipped-for-privacy@newssvr27.news.prodigy.net...

:-)

How is the enclosure machined? I guess it isn't molded since you weren't asking for this.

If you have openings, maybe you could switch to water/laser cutting, in which case you can just make a U shape, or like, cut in the case, just in front of a tact switch.

Hello Fred,

It isn't. If it were I'd just mold in a tongue where a cheap tact switch sits underneath.

Could also have it milled out. But all that would add another processing step and cost. The ideal thing would be a shallow switch with a short piece of tubing around it. The tubing could be made but the push surface of that switch would need to be large enough for an average to large index finger.

Regards, Joerg

google for tactile switches. that ended up being my suggested solution for another post for low travel type microswitch with two form "A" contacts.