silkscreen question

Discussion in 'General Electronics Chat' started by chimera, Aug 5, 2011.

  1. chimera

    Thread Starter Member

    Oct 21, 2010
    Hello there!

    I am about to give a circuit to be professionally fabricated. This is my first circuit that's going to get turned into a PCB.

    So as u can imagine, I have been pulling threads out of every little detail. A little OCD over it I guess.

    I have a question and its really basic.

    Does a silkscreen for, lets a say a SMD component, create a short if its lying over the pads?

    Or it doesnt matter because the copper is lying under it and the silkscreen is not going to conduct?

    I have attached an 'example' jpeg. The green arrow will point to where I am concerned about.

    Thanks for looking!
  2. chimera

    Thread Starter Member

    Oct 21, 2010

    tht was a funny reply. I am sure I will get an answer least a more useful one than the one I got previously.. :p
  3. MartinM

    New Member

    Nov 16, 2009
    No, it won't short anything out but it will stop the component being soldered properly. Don't run silksceen printing over any solder pads. Period.

    Good luck with the board....
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    It will not short, but it ain't gonna solder nice either.

    Don't be surprised if any silkscreen over pads disappears. I have (legal!) access to Orcad PCB Editor (very $$ pro package) and it will automatically with no override delete silkscreen ink over any and all pads.

    Most houses run a design check on your gerbers, the good ones will flag things like this, then either kick your job out till you fix, or just fix it themselves and go.
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    BTW, as SMD parts are so tiny you can waste 50% of your board just indicating where they are I have no issues leaving out values (not a good idea anyway IMHO) and ref designations as you can indicate those on the assembly drawing.

    For an outline I just use lines to show where the long side goes. For a diode like you have I also add a line between the pads on the side of the cathode to mark it.

    It all works till the day you hit serious production and the guy supposed to build it complains you ain't got no fiducials.
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Yep the PCB software will delete any silkscreen (overlay) data anywhere it is over exposed copper (anywhere there is no solder mask).

    It is good practice to generate your Gerber files early (like NOW) and look at them in a Gerber viewer program so you can see exactly what it is doing with your artwork when the Gerbers are generated.

    You might also want to check drill sizes, pros modify some of their components to use the same drill sizes you reduce number of drills, and can negotiate better pricing with the PCB house.

    Also it's very good practice to use rounded corners on SMD pads, this improves solderin immensely. It looks like you are using Eagle, have a look in tools->DRC options I think it is, and try a few mil radius on SMD pad corners. :)
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    NEVER put actual component values on a PCB silkscreen. Ref Designators HELL YES, Component Value HELL NO. It will/might change.
  8. chimera

    Thread Starter Member

    Oct 21, 2010
    Thanks for the input everyone. This forum has always helped me!!

    I have sent my board for production and when it turns up, I will for sure post a picture on this forum (in case someone wants to look :p)

    I will pay attention to the pointers given here :)
  9. nerdegutta


    Dec 15, 2009
    That would be nice. :)