Electronics > Projects, Designs, and Technical Stuff
SMT PCBs subjected to torsion and high G forces
DaveW:
In a high G/torque situation, you will effectively have the PCB acting like a beam. Assuming I'm understanding correctly and the rotation is vertical as shown in the attached image, then the point of maximum inflection/bend will occur in the middle of the PCB. Right under your QFP, which will lever it straight off the board. You may well find just by moving it you eliminate the issue; in a previous job delivering stuff up to 1500g, one of the roles I wrote was not to have anything on the quarter or half lines of the board, and these combined with 2.4mm boards, supported circa every 30mm made everything survive.
Mecanix:
That sounds like a flex-pcb and redesign :(
profdc9:
Ok try again...
I don't see how I can add cutouts all the way across the board. That will completely sever the brushes from the rest of the board. My goal was to allow the brush to bend without torquing the PCB as much. I am thinking of cutting out a 1/4 inch 6061 aluminum plate and epoxying it to the back of the board to add stiffness as well.
So I moved the brushes to the opposite site of the board and flipped the display over so that now the farthest side from the brushes is the LQFP-100 package. All of the components near where the torsion is applied are small components, that is LEDs, and those are lined up with the axis of rotation. Take a look:
Perhaps this will take the strain off of the chip?
enjoy.cowboy:
Have you considered a solution by stacking smaller boards? I had high G and vibration issues when designing boards for a homemade rocket. Having them being circular and with screw-on board spacers to stack them with board to board interconnects more or less solved any bending
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