How to mount LED in a product front panel

[VEGETA]

Light pipes are mechanically mounted to the case and on the PCB side they just hover over the LED. That's the whole advantage - you do mechanical stuff separately from electrical stuff. Minor inaccuracies in LED positioning or board mount within the device won't matter.

The specific one you link has alignment pins that would need alignment holes in the PCB. This is not how this is usually done. But I guess if you are working with off the shelf components, you have to deal with whatever you can get.

And the description says "press fit", so I guess you are supposed to undersize the holes. But this does not sound interesting to me, I don't see how this is useful in any way. You will have more control with a through hole LED with a spacer. It makes more sense to me mechanically.

I think I am a bit lost.

is the light pipe press fitted on top of the led itself on the main PCB, then peeks through the case? or press fitting on the case? I cannot imagine how to press fit it on the case without it being able to be pushed inside... the one i linked has 2 little pipes which I assumed they need to be press fitted in the main pcb.

please correct me.

if i ever gonna go with these light pipes, then smd leds are the choice not through hole ones.

if through holes to be used then we need to see how to fit them firmly on both sides.

I actually prefer smaller size led\pipe to be peeking on top so I am ok with very small diameter ones if available.

[ataradov]

Usually light pipes are fixed to the case and don't even physically touch the LEDs. They don't have to be press fit, they may be mounted any way you like or suits your application. There is a picture in this thread of them being glued to the case.

Yes, the whole point of using light pipes is that you can use SMD LEDs.

I personally would design things around through hole LEDs and regular holes in the case. Only go with light pipes if you are making a custom case and a custom light pipe design. Off the shelf light pipes make no sense to me in most cases, you still have to design your stuff around a fixed product, so might as well design around the LEDs themselves.

If alignment becomes challenging, it is far cheaper to make (3D print) alignment tool, or even custom spacers. They don't have to be pretty, since they will be inside the case.

[Jackster]

They press fit into your case and hover 1-2mm above the SMD led.
They don't go all the way through as there is a mushroom cap on the top to prevent this.
That is why in my assembly photo, I have added some glue to stop them coming back out the same way I pushed them in.
The datasheet for the ones I linked show how they fit in as well as the profile.

[VEGETA]

I don't want any type of manual gluing stuff, no hot glue or anything.

so for through hole leds... you use those plastic stand-offs which have 2 holes for the LED legs? and pick the appropriate standoff size? this way it becomes firm but you would still need to match the lengths with the pcb stand-offs themselves.

I was hoping for some light pipes that would stick to the main board for much easier installation... then it would peek a bit out of the top panel while being firmly installed on main pcb. i can't find why it does not work this way.

Is there any pictures of real products available to demonstrate this? I saw many teardowns but couldn't see an example, or i wasn't interested to notice it.

[mariush]

Digikey also has some things in the Optoelectronics - Lenses    or Spacers

For example, a transparent lens cap that you can press fit from above and then insert through hole led from the other side : https://www.digikey.com/en/products/detail/keystone-electronics/8659/317087

They also have them in various colors , here's the whole list : https://www.digikey.com/short/dd1j0mz3

And here's a red example : https://www.digikey.com/en/products/detail/keystone-electronics/8668/317093
or another red : https://www.digikey.com/en/products/detail/visual-communications-company-vcc/SMB-200-RTP/4515614


You could potentially also check the light bar category, as there are there pieces with 2 or more leds in a case that you could in theory glue to the top pcb/case, or maybe have some thermal/adhesive pad/ some pad between the base pcb and the led bar to keep the led bar pressed into the top cover

Example of such led bar with 2 red leds : https://www.digikey.com/en/products/detail/kingbright/WP934EB-2ID/1747693

Check the Panel indicators / Panel lights as well  , and even the LED spacer sections - maybe you'd find spacers just the right height and in big enough stock that you could get them cheaply.

[ataradov]

you use those plastic stand-offs which have 2 holes for the LED legs? and pick the appropriate standoff size?

You may not need the standoff. The challenge with LEDs like this is to mount them straight and at the right height. Once this done they don't need to be supported. So, how you approach this depends on the design. If LEDs are in the tight spot where no removable jig can be placed, then you would probably have to use a standoff. Otherwise you can design a spacer that you use during assembly and then remove.

I was hoping for some light pipes that would stick to the main board for much easier installation... then it would peek a bit out of the top panel while being firmly installed on main pcb. i can't find why it does not work this way.

The one you linked is press fit into the PCB. You would still need to design some tool to make sure it is inserted perpendicular to the PCB, but it might work.

The idea here is to order some of the tings you think may work and experiment. It is hard to tell what may or may not work in your case.

Is there any pictures of real products available to demonstrate this? I saw many teardowns but couldn't see an example, or i wasn't interested to notice it.

Demonstrate what?

[VEGETA]

I believe the press fit lenses are ok if managed correctly, then the through hole led does not need any standoff or spacer... just soldered and inserted.

Still, the press fit pipes into the main pcb seem the best overall but i also need to make sure when i press it down it does not touch or squeeze the smt led itself. also the size of the led...etc. the drawings does not include all info and i could not find 3d model to check.

I need for now a blue light, so getting a blue smd led with clear pipe of vise versa. what type of smt led works well with the pipe i listed above do you think? for example this led: https://www.digikey.com/en/products/detail/harvatek-corporation/B1931NB-20C007614U1930/15861263

You may not need the standoff. The challenge with LEDs like this is to mount them straight and at the right height. Once this done they don't need to be supported. So, how you approach this depends on the design. If LEDs are in the tight spot where no removable jig can be placed, then you would probably have to use a standoff. Otherwise you can design a spacer that you use during assembly and then remove.

if you solder them and let them peek from the case or top pcb, i guess they can be pressed down or move if not supported by a standoff or spacer.

The one you linked is press fit into the PCB. You would still need to design some tool to make sure it is inserted perpendicular to the PCB, but it might work.

why a tool?

it has 2 legs where you press them till they both click. no way it won't be perpendicular i guess. but my concert is the space for the led is it enough? and what sizes of leds are supported.

The idea here is to order some of the tings you think may work and experiment. It is hard to tell what may or may not work in your case.

well, i might just finish the design, then order a prototype board from pcbway to test its main function... along with that i let them buy a couple of those stuff to test them as you said.

Demonstrate what?

i meant pictures to show all these options we talked about in real product for more clearer picture for someone like me who never done them before

[PlainName]

These are the light pipes I used for a project some time ago: Tru Opto LPC060CTP.

Basically you drill a hole in the case and push these through. There's a lip which stops them going all the way through, and a spring clip on the other side stops them coming back out. Ten second job to mount. LED on the PCB sits under the light pipe and the result is a nice diffuse light on the panel with no hole for nasty stuff to get inside. Use with SMD or PTH LEDs as the whim takes you.

There are many other similar. A lot of light pipes mount on the PCB but that means they can't fill the hole in the front panel (easily - in theory they could be the tolerance would have to be fine enough that they would be a pain to assemble). Generally, those types have a hole with a light behind and don't look quite as neat.

[ataradov]

I need for now a blue light, so getting a blue smd led with clear pipe of vise versa. what type of smt led works well with the pipe i listed above do you think?

No idea, you will have to experiment.

if you solder them and let them peek from the case or top pcb, i guess they can be pressed down or move if not supported by a standoff or spacer.

Again, you are theorizing this, but have you tried? This method is used a lot and it works fine. It also depends on how tall your LED/light pipe needs to be.

why a tool?
it has 2 legs where you press them till they both click. no way it won't be perpendicular i guess. but my concert is the space for the led is it enough? and what sizes of leds are supported.

It is very long, at this length minor misalignment would result in quite a bit of misalignment at the top. Regular LEDs have a domed shape and can generally align themselves quite well. Light pipes with flat top may be more frustrating to assemble. If you pick a light pipe with rounded top or just a short one, it would probably be fine.

But I really see no reason to use a light pipe here.It seems just strange to me. Usually you use light pipes if your outside indicator shape is unconventional or the geometry is such that you can't do it with a simple trough hole LED.

But if you are considering this straight light pipe, then just use a regular LED. Especially if you are not assembling a lot of those boards, since LED part would need to be mounted by hand.

i meant pictures to show all these options we talked about in real product for more clearer picture for someone like me who never done them before

It is hard to think of particular products right away. Here is one example where light pipes make sense :
https://des.gbtcdn.com/uploads/2015/201504/heditor/201504061001509379.JPG / https://www.tag-connect.com/wp-content/uploads/2021/06/ulink-pro-case-opened-with-tc2030-ctx-debug-programming-cable-installed.jpg You can see outside indicators of unconventional shape, they would be impossible with regular LEDs.

Of course, a big advantage of light pipes, even the simple ones is that you may not want to have people with any soldering skills doing final assembly. In case of a light pipe only mechanical assembly is required, and this mya be easier. But this is something I would worry about if I'm making more than 1000 of something. For smaller quantities, I can't see how it would be worth it.