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SirJames , 12-11-2023, 07:58 PM

Hello,

as the title suggests I have a question about green LEDs placed on the bottom side of the industrial control PCB I am designing. PCB is placed behind the machine's front panel and green LEDs are supposed to shine through the transparent part of that panel to indicate power ON.

Every other component on my PCB is either SMD (placed on top) or THT connector (also placed on top side). I am pretty sure that in the first step of assembly, SMDs will be placed on solder paste and reflow soldering will be used. Then by wave soldering all of the remaining components (THT connectors) will be soldered.

Now, is there any way to add 2 or 4 LEDs that will shine to the bottom side of PCB without adding another unnecessary step to assembly process (which would make production more expensive)?

I've found "reverse mount" LEDs but I feel like they aren't that universal and if the manufacturer decides to stop producing them it could be difficult to find exactly the same LED from different manufacturer.

Now, my question is: what would be your solution to this problem?

Robert Feranec , 12-11-2023, 08:15 PM

some leds can be mounted upside down and shine through a hole in pcb

Robert Feranec , 12-11-2023, 08:15 PM

https://www.google.com/search?sca_esv=589872414&q=upside+down+led&tbm=isch&source=lnms&sa=X&ved=2ahUKEwij3e_JmYiDAxWiiv0HHSbQBoAQ0pQJegQICBAB&biw=1920&bih=963&dpr=1

SirJames , 12-11-2023, 08:23 PM

I guess I will go with them. Thanks! Hopefully different manufacturers will be making these with similar footprint dimensions.

QDrives , 12-12-2023, 07:53 PM

I'd say there is plenty to choose from: https://www.digikey.nl/en/products/filter/led-indication-discrete/105?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALAAxwVhUgC6hADgC5QgDKbATgJYA7AOYgAvoQC0AJkQgUkPgFcCxMiASEArEwkhJAZjkLlqkpHL1dUhNHlRThc5d1ixQA
If it is low quantity, you could go for manually mounting TH LEDs.
But to answer your last question: I would go for bottom entry SMD LED.

SirJames , 12-12-2023, 09:46 PM

yeah thanks for info, I guess I will go with these reverse mounted SMD LEDs