My Advanced Realistic Humanoid Robots Project

I soldered on the rest of the SMD components. I noticed the PCB peeled back off the chip in one corner though so I plan to use kapton tape to tape off everything but that corner, use a couple alligator clips to pinch the PCB onto the chip tightly so it can't move, and then use hot air from a heat gun to reflow that corner so it reattaches to the PCB. Once that is done, I will attach jumper leads to the 6 inputs/outputs so I can run a full proper test of the whole circuit using a lab power...

I wanted to be able to get in there and test this board for shorts and check all traces for continuity with my multimeter but felt its leads were too big for this tiny of a board setup. So I came up with this idea to use alligator jumper cables to attach sewing needles to the multimeter probes thereby making the sewing needles the new probes. This way I could get into the tiniest areas and run the tests I wanted. It worked pretty well! I have now tested everywhere quite thoroughly and...

Ok so I had multiple failed attempts to solder the chip on. Despite pretinning the PCB, on both attempts when the solder went molten the chip did not center itself and lock into place as would be expected but instead slid out of position significantly both attempts. After the first attempt I assumed it was the outlet bus/landing pad on the left side of the board that was to blame - it being a larger solder mass than the other solder masses on the other edges of the board - causing the chip...

Ok I managed to apply the UV solder mask today and it seems like it worked quite smoothly. I used the tip of a small sewing needle to spread it over the trace and then held the UV light on it for 10 seconds to play it safe. I used transparent UV solder mask so you can still see the trace but its a bit more murky/cloudy when you see it. I used the tip of an exacto knife to put little scratches on the UV solder mask to test its thickness by feel and test its durability a bit to scratching. And...

Ok so the Relife RL-UVH902 UV fast cure solder mask order has arrived and so has my order for a Relife UV curing light to cure the solder mask quickly and effectively. So now I just need to solder mask off that little trace that goes under the half bridge IC chip.

So the plan I have for the heat sinking main conductors that attach to the bottom pads of the IC chip I decided to draw up to explain it. It will be in layers. First you have the chip on the bottom facing bottom side up so the pads are exposed upwards. Then on the first attachment layer I cut out matching shaped copper plates from copper sheeting and solder that down with low temp solder paste and a soldering iron. In theory, this first layer attachment will basically just be extending the...

Ok I used the tip of my exacto knife to carefully scoop on low temp solder paste and then carefully drag soldered it over the key areas I wanted pre-tinned. There do not appear to be any short circuits and the amount of solder on each pad and trace seems a decent amount to me. I forgot to wipe it with alcohol wipe but have done so since taking this snapshot. The next step is I have to carefully uv cure solder mask that little trace runs under the IC chip. It definitely will short a pad to...

So as I fast approach motor controller wiring phase, I figured I would revisit placement again. Upon further reflection I decided hovering midair motor controllers attached to nothing might not work as they'd perhaps be a bit in the way of getting at the motors and just be a bit overwhelming. I'm not positive on this and could revisit the concept but for now I'm thinking of just mounting it side saddle onto the motor again. I decided to place them side by side with inlets on the output shaft...

Here's the center cutout now which was the last thing I needed to do before soldering down the chip. This access window will enable me to solder the main power lines to the main pads on the bottom of the chip. The circuitboard is aimed at tying into the various perimeter pins of the chip but this window is for the high power lines on a separate layer below. I was able to cut this window out with the highest zoom setting of my magnifier visor (I think like 20x zoom?) and an exacto knife...

I got together my temperature sensor and my hot plate and my glass container and some water and figured out where on the hotplate temp dial I need to be to get the desired water temperature. I then used label paper sticker and marked it off and wrote 118f on it which is the average temperature of that spot on the dial. It has about 15 degrees variance I think up or down. Good enough. Next, I mixed up a batch of water and PCB etchant (Ammonium Persulfate crystals and water mixture) using a...