Corrosion inside brand-new 393 motors

We opened 3 brand new 393 motors last night (serial number 3182AA, all recieved within the last 2 weeks) and there was some sort of corrosion and crystallization on the circuit boards inside the motor, as shown in the picture:

Our area RECF rep told us that this could be “corrosion from the soldering flux,” although I have no idea what that means or how it effects the functionality of the motor. We didn’t get a chance to test the motor, but we know it was brand new when we opened it out of the package yesterday,

Does anyone else have this on recently ordered motors? What about motors from months ago? I want to see how widespread an issue this is.

From what I can tell, it is just some residue from the soldering (attaching the components to the circuit board). It might not look nice, but it shouldn’t have any effect on the operation of the motors. It is probably possible to clean it off with the right cleaning agent, but I would just leave it as it can’t degrade further.

We tend to see this residue on all cheaply made consumer grade boards, here’s a picture of the joystick, same problem.

I do not believe this is an issue apart from a cosmetic one. The ‘green’ solder fluxes, especially the ‘no clean’ ones can leave this sort of residue. We have just become used to PCBs that have been cleaned in hazardous chemicals. There are 'no clean’products out there but would you pay more for a pretty PCB?

The white residue / crystallization is a remnant of the low-residue solder paste used by our manufacturer. This solder paste is commonly called no-clean solder paste. It does not affect the form, fit, function or life of our products. It is acceptable to leave as is.

We are working with our manufacturers to get the boards cleaned better at the end of the production process, but since it isn’t hurting anything we haven’t made a big deal about it.

Let us know if you have any other questions.

I do for the boards I build at work, but then cost is not a huge consideration for us. This is part of a typical (quite old now) board.

Ok, it is good to know that this won’t affect the function or life of the motors. Our mentors thought it was some kind of salt or chemical corrosion from shipping (based on the fact that the new packages aren’t plastic sealed) but if it is only harmless residue then we have no cause for concern.

Thanks everyone for your input!