Optical Flow Sensor - How is it Assembled?

[jgsuw]

Hello everyone,

This is my first post on the Bitcraze forums, however I have been working with Crazyflie and other Bitcraze hardware for a year now (mostly I have interacted with the developer community through git issues). My background is in electrical engineering, I am currently a masters student at the University of Washington with my studies focusing on control theory and embedded systems.

I am interested in building a device which will combine an array of optical flow sensors. Since the Crazyflie flow deck has been a great success, I would like to use the optical flow sensor that it is based around, so that I can leverage the existing drivers produced by Bitcraze. If I am successful, I would like give back to the community by making my own contribution to the ecosystem of Crazyflie sensors and add-ons.

With that in mind, I was wondering how are these sensors, namely the PMW3901MB, assembled onto a PCB? The manufacturer datasheet has no assembly information beyond the land pattern recommendation, whereas I was expecting to see a re-flow profile. Furthermore, I see that the package is classified as a chip-on-board, a type of which I am unfamiliar.

What kind of tools and expertise are required to assemble these sensors on a PCB? Can this be accomplished with a soldering iron, re-flow tool or a re-flow oven?

[tobias]

You probably have to contact Pixart to get the details for production. It probably requires you to sign an NDA with them as well. If you only will be making some prototypes we have successfully soldered the sensors using hot-air and by heating the board from underneath (not blowing on top of the sensor). Also the lens can not be attached when doing this as it can't take much heat.

[jgsuw]

Thanks for your reply Tobias! Yes I am only exploring some preliminary ideas right now, and for the foreseeable future will just be trying out some prototypes. I look forward to trying what you describe.