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PCB Peer Review?

Former Member

If interested i need some help reviewing my design. I havent done any PCB work before and was looking for some review help before i order it.

The layout is attached the power net is 22mm and the Ground is 20mm. The signal will come in through a DB25 and exit on a DB25 power is supplied from an Acopian 28EB5E250 (because i have 28Vdc handy) .

IC:

http://www.deiaz.com/data-sheets/DS-MW-01026-02-D.pdf

 

Newark P/N's:

796949-4796949-4 Socket Adapter

85K7801 Terminal Board

69K7219 Header

89F3212 Cap

66C6057 Cap

 

 

Thanks for the help.

Attachments:
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image

  • Hi Paul,

     

    I had a look at your artwork and the width of the tracks seems small. The width is not only important for the impedance of the track but also for the robustness (mechanical stress on the headers and connectors).

     

    If you switch to SMD capacitors (100nF decoupling on the IC-sockets seems enough) you can move the capacitors as close as possible to the adapter sockets (solder side / bottom side). If the capacitors are too far away they are not effective.

     

    Best regards,

     

    Enrico Migchels

    Power Conversion Design Engineer

    Heliox B.V.

    Best - The Netherlands

    www.heliox.nl

  • in reply to enrico.migchels

    TY for looking.

    All signal traces are 12mm and the only reason I did not go to SMD capacitors is because I have the other ones on hand now.  Is 12mm a large enough width? I can try upping it, but was concerned about clearances and keeping everything on this specific board size.  I have some (http://www.polycase.com/item/dc-46f.html) on hand from another project that i was intending to use here.

    Again thanks for the help.

  • in reply to Former Member

    Do you mean 0.12mm and 0.22mm - if so that's much too small for a simple low cost board.

     

    A good start for minimum cost would be 0.3mm for the signals and try for 1mm for the power.

     

    Your picture doesn't show the vias well enough to comment.

     

    Can you list your design rules from your CAD system ?

  • in reply to michaelkellett

    My appologies i had typed in mm and it should have been mil. When i drew it it was in inches but the software put it all in mil.

    So the vias are 10 mil (.01 in.)

    12 mil for signals

    22 mil for power

    20 mil for ground

     

    So a big difference in overall size.

     

    I upped the power to 38 mil without issues and the ground to 30 mil with no issues. Any larger on the ground and i was running into clearance issues.

     

    The CAD system I am using is Ultiboard and Multisim from National Instruments.

    design rules are all in mil:

     

    Trace width = 12.0

    Max trace width = 393.0

     

    Min trace length = .03

    Max trace length = 39370.0

     

    Min trace neck length = .0393
    Max trace neck length = .0393

     

    Clearance to traces, pads, vias & copper areas = 14.0

     

    Allow pin swapping = yes

     

    Min tool size for drilling = 10.0

     

     

    Thanks for the help.

  • in reply to Former Member

    Those rules should be OK. I would advise you to specify finished hole size rather than drill size - you don't care what drill they use when your board is made you only care about the hole.

     

    The best way to get some workable design rules is to ask the people who will make the board. Many pcb companies have design rules on the web. I use www.pcbtrain.com but there are many others.

  • Hi Paul,

     

    I did some calculations and figured out that the dimensions are in mils. That's ok. Always stay above 10 mils trace width, otherwise your board supplier will have difficulties making that board (will add cost). In general your design should be ok, but reconsider the capacitors. If you make only 1 board you might consider soldering the capacitors on the adapter socket directly, but this could also be done afterwards if the decoupling causes problems.

     

    Good luck.

     

    Best regards,

     

    Enrico Migchels

    Power Conversion Design Engineer

    Heliox B.V.

    Best - The Netherlands

    www.heliox.nl

  • in reply to enrico.migchels
    Thanks for all the help everyone. It is greatly appreciated.