Low profile switches with protection ring?

[Joerg]

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

 

[[email protected]]

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:

On the Dell laptop, isn't it a standard cheapo gull-wing SMT tact
switch with some custom plastic around it? Can't you build this ring
into your housing?

 

[Joerg]

Hello ZWS,

On the Dell laptop, isn't it a standard cheapo gull-wing SMT tact
switch with some custom plastic around it? Can't you build this ring
into your housing?

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

 

[Rob]

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

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:

http://www.tekoenclosures.com or www.polycase.com

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

http://www.maplin.co.uk/Module.aspx?C=SEO&U=SiteMapByDept&ModuleNo=25101

r.

 

[Rich Grise]

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.

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

 

[Joerg]

Hello Rich,

How much can you invest in designing this thing? ...

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

... If you're talking about
the item being thrown into a book bag, how about a slide switch? ...

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

... 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.

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

 

[Fred Bartoli]

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.

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.

 

[Joerg]

Hello Fred,

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

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

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.

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

 

[Joseph2k]

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

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