Well, my first PCB is all designed up, including all manual traces, and a custom part…
I’ve inserted the important layers here, hoping that a few people more experienced than me would check them out before I send it off to get fabbed. Thank you so much!
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Before someone mentions the extra vias, they are there to insure low impedance between the top and bottom ground planes. Probably unnecessary but they’re free.
The board seems awfully big for the parts on it. Is there a case being targeted here? If not, you can save some money by shrinking it.
theatrus:
The board seems awfully big for the parts on it. Is there a case being targeted here? If not, you can save some money by shrinking it.
I think at most I could squeeze about $10 of savings if I was using batcpcb but I’m using 4pcb and with their $33 student special, size isn’t a concern. Another issue is that the 12V supply could have up to a 4 amp load so there will be a pretty big heat sink on that regulator and I wanted to ensure good airflow around it.
hockeyrcks9901:
the 12V supply could have up to a 4 amp load…
If that’s the case, you may want to make your traces larger.
-Bill
phalanx:
hockeyrcks9901:
the 12V supply could have up to a 4 amp load…If that’s the case, you may want to make your traces larger.
-Bill
They are 100 mils right now, is that not large enough? The online calculator I used said 80 mils minimum. The other option I considered was making the same traces on the bottom of the board so the two layers would be the same. I’m not sure if there was anything wrong with that do I just left it on the top only.
You are probably fine at 100mils but with the loads of space you have available, I would make them bigger to minimize temperature rise on the PCB.
-Bill
Check the data sheets for the various regulators to see what they need for bypass caps. The LT1083 specs a 10uF tantalum on the output for stability. The 7805 wants 330n (100n is usually OK) on the input.
Also, you may want to go to higher-value resistors. You are driving the LEDs with 14-20mA; depending on the LED they may be very bright…
/mike
If I were you, I would print out the board layout on plain paper and actually stick all the parts on the page. Just poke the through-hole leads through the paper. This is a great help to ensure you have proper space around connectors, heat sinks, tall parts, etc., and will also ensure you selected the correct footprints.
