Does anyone know of a pushbutton switch
that can be surface mounted to the back
side of a PCB with the actuator button
protruding through a hole in the PCB?

On 27.10.2012 20:33, Jim Stewart wrote:
> Does anyone know of a pushbutton switch
> that can be surface mounted to the back
> side of a PCB with the actuator button
> protruding through a hole in the PCB?

I would hope that such devices do not exist, because they would be 
doomed to fail mechanically.

SMD means you have only the solder joints to keep your part in place. 
For the setup you're looking at that would mean every push of the button 
exerts exactly the kind of force solder joints to PCB pads really can't 
stand: shear-pull away from the board.  That mechanical setup 
practically begs for the pad and a piece of track to be torn loose off 
the base material, leaving your whole button dangling in the wind.

SMD push buttons exist, but there's a reason they always go on the 
front, where the push force can be passed via the back of the switch 
housing directly to the PCB, without stressing the solder joints.

On 28 Okt., 11:28, Hans-Bernhard Bröker <HBBroe...@t-online.de> wrote:
> On 27.10.2012 20:33, Jim Stewart wrote:
>
> > Does anyone know of a pushbutton switch
> > that can be surface mounted to the back
> > side of a PCB with the actuator button
> > protruding through a hole in the PCB?
>
> I would hope that such devices do not exist, because they would be
> doomed to fail mechanically.
>
> SMD means you have only the solder joints to keep your part in place.
> For the setup you're looking at that would mean every push of the button
> exerts exactly the kind of force solder joints to PCB pads really can't
> stand: shear-pull away from the board.  That mechanical setup
> practically begs for the pad and a piece of track to be torn loose off
> the base material, leaving your whole button dangling in the wind.
>
> SMD push buttons exist, but there's a reason they always go on the
> front, where the push force can be passed via the back of the switch
> housing directly to the PCB, without stressing the solder joints.

yep reverse mount smd wouldn't work unless they were glued down or
something

you can get reverse mount:
http://www.e-switch.com/product/tabid/96/productid/9/sename/tl1107-series-tact-switches/default.aspx
but it is through hole and you'll need a milled hole for the switch

-Lasse

On 10/28/2012 7:50 AM, l...@fonz.dk wrote:
> On 28 Okt., 11:28, Hans-Bernhard Bröker<HBBroe...@t-online.de>  wrote:
>> On 27.10.2012 20:33, Jim Stewart wrote:
>>
>>> Does anyone know of a pushbutton switch
>>> that can be surface mounted to the back
>>> side of a PCB with the actuator button
>>> protruding through a hole in the PCB?
>>
>> I would hope that such devices do not exist, because they would be
>> doomed to fail mechanically.
>>
>> SMD means you have only the solder joints to keep your part in place.
>> For the setup you're looking at that would mean every push of the button
>> exerts exactly the kind of force solder joints to PCB pads really can't
>> stand: shear-pull away from the board.  That mechanical setup
>> practically begs for the pad and a piece of track to be torn loose off
>> the base material, leaving your whole button dangling in the wind.
>>
>> SMD push buttons exist, but there's a reason they always go on the
>> front, where the push force can be passed via the back of the switch
>> housing directly to the PCB, without stressing the solder joints.
>
> yep reverse mount smd wouldn't work unless they were glued down or
> something
>
> you can get reverse mount:
> http://www.e-switch.com/product/tabid/96/productid/9/sename/tl1107-series-tact-switches/default.aspx
> but it is through hole and you'll need a milled hole for the switch
>
> -Lasse

I have seen transformers mounted with part of the unit protruding 
through the board, but still soldered on the top side.  Maybe a switch 
like this exists, it recesses into the board from the top, not stressing 
the solder joints but is very low profile on the top side.

Rick

In article <k6k1eg$sbb$1...@dont-email.me>, g...@gmail.com says...
> On 10/28/2012 7:50 AM, l...@fonz.dk wrote:
> > On 28 Okt., 11:28, Hans-Bernhard Bröker<HBBroe...@t-online.de>  wrote:
> >> On 27.10.2012 20:33, Jim Stewart wrote:
> >>
> >>> Does anyone know of a pushbutton switch
> >>> that can be surface mounted to the back
> >>> side of a PCB with the actuator button
> >>> protruding through a hole in the PCB?
> >>
> >> I would hope that such devices do not exist, because they would be
> >> doomed to fail mechanically.
> >>
> >> SMD means you have only the solder joints to keep your part in place.
> >> For the setup you're looking at that would mean every push of the button
> >> exerts exactly the kind of force solder joints to PCB pads really can't
> >> stand: shear-pull away from the board.  That mechanical setup
> >> practically begs for the pad and a piece of track to be torn loose off
> >> the base material, leaving your whole button dangling in the wind.
> >>
> >> SMD push buttons exist, but there's a reason they always go on the
> >> front, where the push force can be passed via the back of the switch
> >> housing directly to the PCB, without stressing the solder joints.
> >
> > yep reverse mount smd wouldn't work unless they were glued down or
> > something
> >
> > you can get reverse mount:
> > http://www.e-switch.com/product/tabid/96/productid/9/sename/tl1107-series-tact-switches/default.aspx
> > but it is through hole and you'll need a milled hole for the switch
> >
> > -Lasse
> 
> I have seen transformers mounted with part of the unit protruding 
> through the board, but still soldered on the top side.  Maybe a switch 
> like this exists, it recesses into the board from the top, not stressing 
> the solder joints but is very low profile on the top side.

Personally if the switch is so close to the outside, that you need to 
save height, I would be looking at touch sensors anyway, just areas of 
PCB track.

-- 
Paul Carpenter          | p...@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
<http://www.gnuh8.org.uk/>  GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
<http://www.badweb.org.uk/> For those web sites you hate

On 28.10.2012 21:34, Paul wrote:

> Personally if the switch is so close to the outside, that you need to
> save height, I would be looking at touch sensors anyway, just areas of
> PCB track.

But those come with their own can of worms attached that's bigger and 
heavier than an entire PC keyboard's worth of conventional push buttons.

SMD push buttons are routinely below 4 mm in height, and can be had down 
to 1.2 mm.  Rubber-mat-with-conductor-pads type buttons are of similar 
height.  If you can fit neither of those, then your PCB is entirely too 
close to the front panel ;-P

On 10/28/2012 5:53 PM, Hans-Bernhard Bröker wrote:
> On 28.10.2012 21:34, Paul wrote:
>
>> Personally if the switch is so close to the outside, that you need to
>> save height, I would be looking at touch sensors anyway, just areas of
>> PCB track.
>
> But those come with their own can of worms attached that's bigger and
> heavier than an entire PC keyboard's worth of conventional push buttons.
>
> SMD push buttons are routinely below 4 mm in height, and can be had down
> to 1.2 mm. Rubber-mat-with-conductor-pads type buttons are of similar
> height. If you can fit neither of those, then your PCB is entirely too
> close to the front panel ;-P
>

You could use the Forth methodology.  If the problem is too hard to 
solve, solve a different problem.

Rick

On 28 Okt., 22:53, Hans-Bernhard Bröker <HBBroe...@t-online.de> wrote:
> On 28.10.2012 21:34, Paul wrote:
>
> > Personally if the switch is so close to the outside, that you need to
> > save height, I would be looking at touch sensors anyway, just areas of
> > PCB track.
>
> But those come with their own can of worms attached that's bigger and
> heavier than an entire PC keyboard's worth of conventional push buttons.
>
> SMD push buttons are routinely below 4 mm in height, and can be had down
> to 1.2 mm.  Rubber-mat-with-conductor-pads type buttons are of similar
> height.  If you can fit neither of those, then your PCB is entirely too
> close to the front panel ;-P

my immediate guess is that he wants to use the pcb as the front panel

All components on the back side, button actuators protruding through
holes in the PCB, add some reverse mount leds silkscreen what ever
text
needed

-Lasse

On Saturday, October 27, 2012 1:33:36 PM UTC-5, Jim Stewart wrote:
> Does anyone know of a pushbutton switch
> 
> that can be surface mounted to the back
> 
> side of a PCB with the actuator button
> 
> protruding through a hole in the PCB?

I saw a patent for a tact switch like this, but it was not listed as being assigned to anyone.

You didn't mention if you needed push-push or momentary.  For momentary, how about a snap dome, they are pretty low profile.  I've used a few from snaptron on prototypes and I think Omron also makes them.

l...@fonz.dk wrote:
> On 28 Okt., 22:53, Hans-Bernhard Bröker<HBBroe...@t-online.de>  wrote:
>> On 28.10.2012 21:34, Paul wrote:
>>
>>> Personally if the switch is so close to the outside, that you need to
>>> save height, I would be looking at touch sensors anyway, just areas of
>>> PCB track.
>>
>> But those come with their own can of worms attached that's bigger and
>> heavier than an entire PC keyboard's worth of conventional push buttons.
>>
>> SMD push buttons are routinely below 4 mm in height, and can be had down
>> to 1.2 mm.  Rubber-mat-with-conductor-pads type buttons are of similar
>> height.  If you can fit neither of those, then your PCB is entirely too
>> close to the front panel ;-P
>
> my immediate guess is that he wants to use the pcb as the front panel
>
> All components on the back side, button actuators protruding through
> holes in the PCB, add some reverse mount leds silkscreen what ever
> text
> needed

Close.  Using the PCB as an end panel for an extruded
enclosure.  Small LCD mounted on the inside pointing
out through a hole.  Switches mounted on the backside
poking through holes, laser cut Mylar overlay on the
front.

Hans concern about the switch lead fragility is something
I haven't thought about and needs to be considered.