criticality of using vias over silkscreen

[abhi002]

hi Friends,

i wanted to know about the criticality of using vias over silkscreen(legend) outline.I do not put vias intentionally but at the time of gerber generation we feel this problem.Again we have to do lots of rework.
is there any way to avoid this problem orelse can we just ignore it?

suggestions are most welcome!!

abhi

 

[Old Nick]

Could you try and explain that better.

Are you concerned about solkscreen/lettering going over via's?

If so. don't worry about it, the materials they use are non conductive.

 

[abhi002]

ya exactly ,i am concerned about solkscreen/lettering going over via's.
also i am worry beacause the material used is non-conductive for legend printing.It may disturb the signal flow through the via.

 

[rikie_rizza]

It wont disturb signal flow over the via. Via are made first, than solder mask, than lettering. No need to worry... unless your via is not a through hole type so you must fill the hole with solder.

If that is not the case, no worry are needed. I, thou, always move lettering from being placed over vias. the reason is... the letters are can not be read clearly. it's just a matter of esthetic.

 

[Awarapunshee]

If the via's are not cover with solder mask, even then legend/silkscreen do not disturb the signal flow. It is only PTH that can disturb signal flow if not properly done.

Regards

 

[Rame]

Hi,

You need not to worry,since the silkscreen is non conductive,even it is over the pth to another pth....please study the material properties in the fabrication process,it will help you understand better.

Here is the link underneath,go through the process,

https://www.thinktink.com/stack/volumes/volvi/filmimag.htm#Photo_resist

https://www.thinktink.com/stack/volumes/volvi/pcbproto.htm

Regards,

Ramesh

 

[vijaya_narayana]

the ledegend will cover the via it will difficult for us to trouble shoot the board after populating when the via is covered by the ledgend

 

[rikie_rizza]

Wow, there are legend, silkscreen, lettering, imprint, what else?

 

[touringmike]

The software package I use has a silkscreen generator that breaks text and lines to a user-set point beyound conductive pads. I normally use a break off point of .007" (0.18mm) because silkscreens have a tendancy to stretch.

If you don't have this capability, your next best option is to manually modify the silkscreen so you don't have these problems.
If the silkscreen covers a pad/via, and you don't want it there, move it, change the size, rotate it, or delete it.


Any good board designer should know this.

 

[abhi002]

thanks friends,

The reasons i found after the discussion:
1- esthetic look
2- trouble shoot the board

Actually i also not prefer via over silkscreens.Now i got the answers,why.

thanks a lot
//for touringmike
which software package you use?

 

[cyberrat]

Simple, just like you make an 0.008" oversized gerber of the pads, make one for the pads AND vias and call it "silkscreen scratch" and it will be used as a composite layer for the legend so that wherever pads/vias are on the scratch layer, they get removed from the silkscreen layer.

although you can jst ask your board manufacturer to do this as they will usually have a macro to do it.

 

[Awarapunshee]

thanks friends,

The reasons i found after the discussion:
1- esthetic look
2- trouble shoot the board

Actually i also not prefer via over silkscreens.Now i got the answers,why.

thanks a lot
//for touringmike
which software package you use?

I use PCAD2002, Pcad4.51( DOS base and Old version of Pcad2002). (OrCad a little bit).

 

[flypcb]

Just ignore this problem, the PCB shop engineer will remove the silkscreen overlap the via holes. Not the whole silkscreen word, just the part is overlapped. So in most case, you still can recognize the silksreen word.
In the past, Engineer relies a lot on silkscreen to differentiate the exact components. Nowadays, most of us depends on PC to confirm the component parts. No silkscreen on some parts is not a big problem.
In fact, a big number of companies have cancelled silkscreen on the PCB. For instance, Siemens is a good example.

 

[chinta]

OK, Here are three things you can do it.

1. Leave it over the masked via holes. This will not cause any problem.
2. If your CAD package have tha capability, clip the silkscreen text away from the via hole pads. So you won't see any silkscreen on via holes.
3. Ask the fabricator to clip the silkscreen which ever is falling on the via holes by certain distance so that they can edit the gerbers. CAM facility will have this function.

 

[cyberrat]

Or you can design your board so that you do not have text over the vias in the first place, if its an issue for you.

common sense really.