Via soldermask quality question

Discussion in 'General Electronics Chat' started by tracecom, Jan 6, 2014.

  1. tracecom

    Thread Starter AAC Fanatic!

    Apr 16, 2010
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    In the attached photo, there are two vias. The one nearer the top left does not have a good soldermask covering, whereas the one nearer the lower right does have a good soldermask covering. In this particular PCB, it doesn't matter, but in another layout, the lack of a soldermask could be significant.

    Should I complain to the PCB house, or is this acceptable?

    Thanks.
     
    Last edited: Jan 6, 2014
  2. mcgyvr

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    Oct 15, 2009
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    Its a VIA not a plated through hole.. soldermask really doesn't matter there..
    Did you request vias be "tented" or plugged or anything?
     
  3. tracecom

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    I was hoping you would reply because the layout was done in DipTrace.

    No, I didn't request anything special. I thought vias were always plated through; isn't that true?

    Oh, and I think I saw today that there is an option in Gerber file prep for vias to be left unmasked, but I didn't select that.
     
  4. mcgyvr

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    Vias are always plated through.. What I meant by the "via not a plated through hole" is that the soldermask for a via doesn't really matter like it does for a regular plated through hole.

    But how the soldermask is handled for a via is either specified by you (plugged/tented,etc..) or mostly left up to manufacturers discretion.

    Some good info here..(just the first link I came across)
    http://www.epectec.com/pcb/plug-via/

    Id have to see your gerber files but I suspect they were not included in the masking and as such they were going to be "tented" and thats usually never guaranteed to always happen. as you can see

    Next time make sure the mask includes via holes if it didn't already... Nothing to be concerned with though..
     
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  5. t06afre

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    May 11, 2009
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    We had a related discussion about this here http://forum.allaboutcircuits.com/showthread.php?p=677415#post677415
    I do not know DipTrace. But in the tools I use. The solder mask expansion. Can be defined either on component level or by a global design rule setting or a combination of both. So it could be that the solder mask expansion on those components are a result of a component specific setting
     
  6. #12

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    Nov 30, 2010
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    Could you guys dumb this down for me? All I see is that (upper) A is not through plated and there's a hair in the soup. Are you saying you wanted the surface rims of the through holes to be painted green?
     
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  7. mcgyvr

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    He was just expecting both "via" holes to be capped or covered completely with soldermask..
    and it IS through plated it just didn't get hot air solder leveled because its partly covered with masking.. the mask just "sank" into the hole more than the other..
     
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  8. tracecom

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    Shhh! Now, everybody will want one.
     
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  9. tubeguy

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    Nov 3, 2012
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    What's worse?
    A hair in the soup or a hare in the soup? :rolleyes:
     
  10. bance

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    Aug 11, 2012
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    That would depend on whether it was 'Tomato soup' or 'Hare soup' !
     
  11. ErnieM

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    Apr 24, 2011
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    First you should check the mask layer gerber file and see if there is a hole over that via, but without any other fill I wouldn't expect a via to fill 100% of the time with the mask material.

    I say check the gerber as it appears to me the mask is simply non existent on that "via," and perhaps it is just a small thru hole. I've had that happen in my projects when I change the via size mid way.

    It doesn't hurt to query your board house and ask suggestions for times this is a serious error (as opposed to simply not desirable but well tolerated).

    I cannot tell from the image if the thru holes are plated or not.

    An angle to the board would help show the innards. It may also let the hairball fall off.
     
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