Electronics > PCB/EDA/CAD

What do you think of my PCB design?

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Regarding the decoupling caps, I agree, I just forgot to add them :). The teacher is an idiot yes, my knowledge far surpasses his (i'm also an idiot, still learning), but it's high school so it's understandable. He's still stuck with single sided boards with like 100 thou track widths max, I want to get the highest grade possible so I have decided to get the board professionally made with SMT parts. Lovely bloke though.

I'm going to integrate this schematic into my main board (Which will be controlling stepper motors, LCD, eeprom etc) so this was a useful exercise.

In future I'll be: routing gnd and power (And data) first, with larger track sizes and the most direct route, adding decoupling caps, making sure the angles are OK (I used a default option in Eagle for the majority).

Is putting a via on a SMD pad OK? bringing the wires out seems a little silly to me...


--- Quote from: Christopher on June 15, 2012, 12:17:19 pm ---Is putting a via on a SMD pad OK? bringing the wires out seems a little silly to me...

--- End quote ---

no vias in pads, unless you instruct the board manufacturer to cap them and plate over with copper. a via in the pad will wick away all the solder to the other side of the board and leave your component with little to nothing holding it on.

Careful with Howard Johnsons statements ! He is right , but ....

1) he is talking about purely digital signals where you already have a large noise margin

2) talking about single signals. Differential or buses change the picture as the bend inserts delay and skew.... which he explains towards the end . The problem is most people only remember 'it doesn't matter', they forget the conditions.... Because they stopped reading halfway through.

3) the article is 12 years old... We are way beyond the rates he talks about. SATA, PCIX, Thunderbolt, push at triple to quadruple the speeds he talks about...

4) he talks about 8 mil traces... On a modern board with fine pitch FPGA we are going down to 3 mil track and gap ... And then manufacturing will start growling at you because the corners become an etchant trap... For pcb etching an inner corner should never be sharper than 90 degrees, 135 is preferred. In small features the sharp corners become etchant traps and there is a tendency to etch them open.... Try doing a flip chip board with 1.7 mil track...


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