1
\$\begingroup\$

I am using one of these Side LED's on the edge of a PCB to illuminate it through the light guide.

http://www.digikey.com/product-detail/en/osram-opto-semiconductors-inc/LB%20A67C-P2R1-35-Z/475-1163-2-ND/808879

These side LEDs were oriented wrong on my PCB design (placed inwards instead of outwards).

I can't think of a way to solve the problem on the board.

Can anyone think of a temporary short term fix for this?

I can solve the the design issue long term on the board.

\$\endgroup\$
  • 1
    \$\begingroup\$ Your pcb design or picture, and schematic w would help. \$\endgroup\$ – Passerby Apr 1 '16 at 7:23
  • \$\begingroup\$ Turn around and reroute? \$\endgroup\$ – PlasmaHH Apr 1 '16 at 7:37
  • \$\begingroup\$ @PlasmaHH : PCB arrived already and its too expensive(i mean in terms of lead time) now to re design \$\endgroup\$ – arjun c Apr 1 '16 at 8:18
7
\$\begingroup\$

I'm going to have a go but I'm no master artist so you'll have to forgive me for the crude drawings. I'm assuming that by 'oriented wrong' you mean the cathode and anode pads are in opposite positions than they should be. If it's a temporary fix then you can get round it with a sharp knife and a bit of wire with careful soldering

enter image description here

The grey is meant to be the LED pads, dark green is your tracks/traces, orange is the exposed copper and the red and blue are meant to be wires.

This way your LED will still have a solid connection to the board. You can always use a bit of epoxy afterwards to insulate the bits of exposed tracks if it causes an issue

|improve this answer|||||
\$\endgroup\$
  • \$\begingroup\$ Hot glue (ie, plastic from a glue gun) is an alternate approach .vs. the epoxy. \$\endgroup\$ – Ecnerwal Apr 1 '16 at 15:29
  • 1
    \$\begingroup\$ Hot glue, at least some types, is conductive. And there is at least one silicone type that will corrode copper. Don't use it. \$\endgroup\$ – user65586 Apr 1 '16 at 16:57
  • \$\begingroup\$ I have also seen cyanoacrylate used... (super/crazy glue) Just a dab to hold the floppy bits of blue wire down. \$\endgroup\$ – Daniel Apr 1 '16 at 17:40
2
\$\begingroup\$

You might try looking for a similar LED module with reversed lead polarity.

Or for a temporary fix you might just glue the LED module upside down at the original position, then the leads would be correct (left and right). Then using fine wire manually solder the PCB pads up to the correct LED module pads.

Since the module leads are .100" (2.54mm) spacing you might even try using a 2-pin .100 spaced male header and solder that to the far inner edge of the pads first, then solder the module upside down to the upper part of the header pins. (You might also try soldering a right angled header to the back of the module first, so the pins wrap around the back, then solder the opposite ends of the pins to the pads.)

|improve this answer|||||
\$\endgroup\$
  • \$\begingroup\$ I understand your suggestion but I need one clarification. Glue the LED on the solder pads ?In that case,glue will be non conductive?So how to solder the header then. \$\endgroup\$ – arjun c Apr 1 '16 at 12:05
1
\$\begingroup\$

You can place them with the contacts on upper side, then with a thin wire make the contacts criss-crossed. A little attention is needed, but it is a solution :)

|improve this answer|||||
\$\endgroup\$
0
\$\begingroup\$

The LEDs are slightly higher than the centre-line of the device. This means that you can invert them and have enough space underneath for some connections while maintaining the correct LED centre-line height. Also the leads wrap around the back of the package which will be a help.

enter image description here

  1. Cut a bare solid conductor of suitable gauge about 25 mm long and bend it into a U-shape 2.54 mm wide to match your PCB pads. Tin the wire and solder it to the pads with the U at the rear of the LED.
  2. Bend the wire up from the board at right-angles to line up with the rear of the LED.
  3. Glue the LED in upside-down on top of your joints. Solder on the back below the level of the top of the chip.
  4. Cut off the U flush with the top of the LED.

enter image description here

|improve this answer|||||
\$\endgroup\$
  • \$\begingroup\$ :thank you for detailed explanation.will try this option and let you know \$\endgroup\$ – arjun c Apr 2 '16 at 10:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.