Related to my question from last time (Pin mounts horizontal pin rows): I have the same device, but now I don't want to bend the legs, rendering SIP/DIP sockets useless. But I do not care anymore about the removability. What are then good ways to fixate the device on a pcb? One idea I had was to use overdimensioned smd pads, and solder it on them. Is that useful, or are there better ways?


You could use some right-angle female connector strips, but obviously from the topology once the leads are inserted and the strips soldered into a PCB it will no longer be possible to remove the laser. Photo from Sparkfun, but the parts are widely available from any distributor:"-

enter image description here

  • 1
    \$\begingroup\$ Well, you could put a matching SIP header on the PCB, but this is asking for trouble as both the laser and TEC draw about 2.2A each. \$\endgroup\$ – rdtsc Feb 17 '16 at 14:36
  • \$\begingroup\$ @rdtsc Indeed. Probably within ratings but with the contacts just floating there, the ratings may not be valid. \$\endgroup\$ – Spehro Pefhany Feb 17 '16 at 15:50

It isn't mentioned in the datasheet, but first of all, this module needs to be heat-sunk (bolted to something thermally conductive) to keep it cool. A dab of heat-sink grease (or pad) should be used to ensure good thermal transfer. The laser diode can be pulsed with up to 2.2A of current, which would quickly overheat it otherwise.

It looks as though it is intended to have a cut-out made on the PCB, and the device placed through the cut-out, with the legs touching the PCB, which are then soldered. Finally, mounting screws secure it to the case or a heat sink.

Interestingly, it also includes a TEC or thermo-electric cooler (peltier junction) device to help cool it, and a thermistor to measure it's temperature. If you do not already have a "driver" circuit for this beast, one would be required to:

  • Measure the temperature of the device (thermistor.)
  • Send power pulses to the laser (carefully regulated and limited.)
  • Monitor laser power output, adjust power accordingly (photodiode.)
  • As the temperature increases, begin powering the TEC to maintain temperature.
  • If the temperature cannot be controlled (too hot), shut down device.
  • If current or voltage limits to the laser are exceeded, shut down device.

Such a driver is likely something like one of these: http://www.laserdiodesource.com/laser-diode-drivers

I did manage to find one paper mentioning this module, but cannot find a reference driver circuit.

Designing such a driver will not be an easy or simple task.

  • \$\begingroup\$ I have already a driver, and a cooler. The problem is our current fixation system (aka free-air-connections). Thus I wanted to design a pcb for that (with a gap in the middle) where the diode can be fixed onto. \$\endgroup\$ – arc_lupus Feb 17 '16 at 14:20
  • \$\begingroup\$ Good, then just make a cut-out slightly larger than the laser base, optical fiber, and screw holes, and leave appropriate pads to solder the leads to. Could place the laser through the PCB, or easier, place the PCB on top of the laser and use bottom pads. Many PCB fab houses can route out areas of the PCB using a 100mil/2.54mm router bit. If your PCB is large, you will have to use PCB standoffs of some height (to be calculated by where you want the base of the laser module to reside - on the enclosure, through the enclosure?) \$\endgroup\$ – rdtsc Feb 17 '16 at 14:32

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.