First 4 layer pcb attempt

[Makaram]

https://i.imgur.com/hhSIIlZ.jpg
Link to picture showing all 4 layers.
This is my first attempt at 4 layer pcbs and would like some expert advice.
E.g. hows that pour stitching looking? Too little? Do I need the top and bottom ground planes?

The circuit is essentially a RN42 bluetooth modules, a pic32mx220f032d, a buck regulator and an H bridge hopefully capable of up to 15A @ 12v.

As for EMI reduction I've got a ferrite bead and 1nF bypass cap feeding the 3.3v plane for my mcu and all the RF stuff is handled by the RN42 module.

Thanks for any advice you guys can provide.

 

[Flyback]

just keep those current loops tight and as low in area as possible.......and enough cooling copper.
Did you use eagle?
https://pcblayout1.wordpress.com/pcb-layout-software-packages-need-better-tutorials/

eagle is Germanys most popular industrial package for 4 layers and less.

 

[ronsimpson]

It looks like you have done this before. Good wide traces. Lots of copper. Many feed-throughs in parallel.

You feed-through clearance is larger than I use.
Is there a thermal pad under the 44 pin IC?

 

[Makaram]

Thanks, that's very encouraging to hear as I'm self taught so am often unsure of my designs.
Does the term 'feed-through' refer to the via arrays used to connect pours?
There is no thermal pad under the Pic but I feel that my choice of mcu might be overkill in the end and may opt of a qfn package later.

 

[ronsimpson]

via....yes

I did not look to see what the heat rise is on the high current traces. Some times I do not put solder mask over the high current traces. The solder build up helps a little. The solder mask is a insulator for heat. If you remove solder mask talk to me first.

 

[Flyback]

The solder mask is a insulator for heat

I thought the copper corrodes without the resist over it?
also, resist is just a very thin film, does it insulate that much?

 

[crutschow]

I thought the copper corrodes without the resist over it?
also, resist is just a very thin film, does it insulate that much?

If the board is wave soldered then all the areas without solder mask will have a coating of solder. The reduces trace resistance some and prevents the copper from corroding.

 

[ronsimpson]

My PCBs come with no exposed copper. There is solder over all open copper areas.

If you look at the "PC" power supplies I made in China they pile solder on the high current traces.

 

[Flyback]

thanks, what if they don't wave solder...how do they then manage to pile solder on the copper traces?

 

[crutschow]

With a soldering iron.

 

[Flyback]

by hand for every pcb?

 

[ChrisP58]

by hand for every pcb?

How else? But if you need solder built up on a lot of boards then it makes sense to wave solder them, even if that's your only reason to do so.


As for the earlier question about leaving leaving bare copper exposed when opening up the solder mask, that really isn't a problem. The board fabricator will treat those areas just like they do exposed component pads and plate those areas with tin or tin/lead. So there will be no bare copper to corrode.

 

[dougy83]

thanks, what if they don't wave solder...how do they then manage to pile solder on the copper traces?

All PCBs that I've had manufactured have had a coating on all pads & exposed copper of gold or tin-lead (HASL). I'm referring to the blank PCB, so no wave soldering or other assembly steps have taken place.