The 0603 SMD LEDs on the current design was great but as I start to fit it into the AMT model, about 30% of these fragile LEDs get knocked off their solder pads by the plastic half-rings. So, I started to solder them in a slightly smaller radius. This did minimise the issue but I have still not solved the other two issues.
THE ISSUES
The first issue is that hand-soldering this board takes hours. There are 8x 0603 network resistors, 24x 0603 fragile LEDs, and 8x 5370 LEDs with each needing their own soldering techniques and also, testing and re-testing for every step with the multimeter to make sure it is connected.
The second issue is, aligning the 24x 0603 in the right polarity and away from the edge is really a pain in the ass.
OK, make that three issues. The third issue is the constant testing and re-testing of every soldering to make sure the components are well connected. It happened once when after taking it to a friend, one of the 0603 network resistor had a bad solder joint. At first I thought it was one of the 0603 LEDs but after some probing, it was that resistor. The problem showed itself when the board was ‘flexed’ slightly during transport. Yes, even a hard FR4 board also flexes even though they feel and look tough.
So, the only answer is to either get them populated from PCB manufacturers or, do some reflow soldering. And this is where the earlier 0603 LEDs problem must be taken care of. I need to re-design the Engine PCBs to have the 0603 LED solder pads placed slightly in, about 0.26mm. I call this version 5.0
HOW IT IS DONE
In the image below, the original reference circle (green) will be replaced by the newer smaller circle (yellow). This means I have to move the LEDs from the green circle to the Yellow circle. I will place the LED’s new position where the thin white lines intersect with the yellow ones. The extra LED (000) is to help me get the alignment angle and position right. Then move the actual LED onto the new position. All 24 of them. Luckily, I designed the board to be used for both sides of the Razor Crest engines.
Then, I re-aligned the tracks (red) to make sure they do not short with the repositioned LEDs solder pads. There is an easier way, which is to rip up all the tracks and use the autorouter instead. This can cut down a lot of time. After that, the remaining changes would be how the text and lines are added/ re-arranged/ deleted.
THE DIFFERENCE
The following image shows the subtle differences between version 4 and version 5. After moving all 24 0603 LEDs closer to the center, I rearranged the traces and also, made a common ground ring. More importantly, the round small white circles are to denote the polarity of the 0603 LEDs and also, shorten some texts as well. But other than that, all the positions of the components remain the same.
