Layout question: TOP or BOTTOM for HAT PCB

Thread Starter

Rodrigo de la Torre

Joined Feb 22, 2016
2
Hi guys,

I am checking some online PCB designs for making my Raspberry HAT (figure 1).
figure 1
And I am confused with the wiring layout on female pin headers. I did vias (thru-hole) for connecting top with bottom layout like the figure 2. Given that I will weld the header on top layer for a HAT (figure 1).
figure 2
But in the figure 3 and 4 for example, the designers, with the same idea for the HAT, didn't make the connection between both layouts. They only wired the bottom component to the pin header in the bottom layout. Can you explain to me the reason why they don't connect both layout?
figure 3

figure 4

I appreciate your replies and time.
 

dl324

Joined Mar 30, 2015
13,328
Welcome to AAC!
But in the figure 3 and 4 for example, the designers, with the same idea for the HAT, didn't make the connection between both layouts. They only wired the bottom component to the pin header in the bottom layout. Can you explain to me the reason why they don't connect both layout?
When you say "both layouts", do you mean both layers? It would be helpful if you indicated an example of what you're questioning.
 

Thread Starter

Rodrigo de la Torre

Joined Feb 22, 2016
2
Hi Dennis!

Yes, both layers (top and bottom). I mean that the female header of the HAT PCB need to be welded on TOP layer. If the PCB has components in top layer like SMD, I only wire on top layer. In another hand, if the PCB needs a bottom connection, I used VIAS (yellow arrow in the figure). That I don't understand is why the designer don't use VIAS to connect other pins of the header (magenta arrow in the figure).

FIGURE 5.png
Thanks for your time
 

dl324

Joined Mar 30, 2015
13,328
That I don't understand is why the designer don't use VIAS to connect other pins of the header (magenta arrow in the figure).
There are no traces on the top going to the pads you indicated in magenta. If there were, the plated through hole would connect top to bottom.

For the traces circled in yellow, I agree, they just didn't turn on vias.

Personally, I wouldn't feel very confident in using work from someone who did board layout like that. Too many 90 degree bends and unnecessary congestion.
 
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