Stop Mask Error - Silk Layer

Thiago Henrique wrote on Sun, 31 January 2010 13:47

I am getting the Stop Mask error on DRC because the silk screen layer

and text is overlapping the stopmask. Can I keep this and send to board

manufacturer, for automated assembly (maybe without silkscreen on the

board) or should I correct? I would be a big trouble to correct.

Most board houses will automatically clip the silkscreen to the soldermask,

but it's bad practice to rely on that and you need to check with the board

house to be sure.

Why is it "big trouble" to fix it the right way?  So far I haven't

ecountered such a problem and it's hard to imagine how you'd run into one

without something stupid going on.  If the offending silkscreen is coming

from a name or value, then it's easy enough to move it, resize it, or

delete it.  If it's coming from tPlace (or bPlace) in a library part, then

that's a badly made part and should be fixed.  Library parts shouldn't have

silkscreen so far outside their own outline that a pad of another part

could be placed there.

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Thiago Henrique wrote on Sun, 31 January 2010 13:47

I am getting the Stop Mask error on DRC because the silk screen layer

and text is overlapping the stopmask. Can I keep this and send to board

manufacturer, for automated assembly (maybe without silkscreen on the

board) or should I correct? I would be a big trouble to correct.

 

Most board houses will automatically clip the silkscreen to the

soldermask,

but it's bad practice to rely on that and you need to check with the board

house to be sure.

 

Why is it "big trouble" to fix it the right way?  So far I haven't

ecountered such a problem and it's hard to imagine how you'd run into one

without something stupid going on.  If the offending silkscreen is coming

from a name or value, then it's easy enough to move it, resize it, or

delete it.  If it's coming from tPlace (or bPlace) in a library part, then

that's a badly made part and should be fixed.  Library parts shouldn't

have

silkscreen so far outside their own outline that a pad of another part

could be placed there.

--

Browser access to CadSoft Support Forums at http://www.eaglecentral.ca

I see. Please check the picture attached. I resized the silkscreen frame, it

is inside the Stop Mask. What do you suggest? To resize the stop mask also?

Attachments:

On Sun, 31 Jan 2010, Thiago Henrique Rodrigues wrote to us saying :

 

I see. Please check the picture attached. I resized the silkscreen frame, it

is inside the Stop Mask. What do you suggest? To resize the stop mask also?

 

I would suggest doing the silk screen frame like most of the Eagle

libraries. That is, the bits which should be clear of the stop mask (two

short parallel lines) should be on the tPlace layer, while the bits that

overlap the stop mask should be on the tDocu layer. This allows the

designer to see the whole outline when placing components, but by

excluding tDocu and bDocu from the CAM job you send a trouble-free silk

screen to your board house. This does need a bit more up-front care and

effort in creating library parts, but it makes life easier in the long

run.

--

Rob Pearce                       http://www.bdt-home.demon.co.uk

The contents of this | Windows NT crashed.

message are purely   | I am the Blue Screen of Death.

my opinion. Don't    | No one hears your screams.

believe a word.      |

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On Sun, 31 Jan 2010, Thiago Henrique Rodrigues wrote to us saying :

 

I see. Please check the picture attached. I resized the silkscreen frame,

it

is inside the Stop Mask. What do you suggest? To resize the stop mask

also?

 

I would suggest doing the silk screen frame like most of the Eagle

libraries. That is, the bits which should be clear of the stop mask (two

short parallel lines) should be on the tPlace layer, while the bits that

overlap the stop mask should be on the tDocu layer. This allows the

designer to see the whole outline when placing components, but by

excluding tDocu and bDocu from the CAM job you send a trouble-free silk

screen to your board house. This does need a bit more up-front care and

effort in creating library parts, but it makes life easier in the long

run.

--

Rob Pearce                       http://www.bdt-home.demon.co.uk

 

The contents of this | Windows NT crashed.

message are purely   | I am the Blue Screen of Death.

my opinion. Don't    | No one hears your screams.

believe a word.      |

I switched the silk frame from tPlace to tDocu layer. The DRC is no longer

generating errors. I hope this is ok for the pcb house.

"Thiago Henrique Rodrigues" <thiago_hr@yahoo.com.br> wrote in message

news:hk4j80$llh$1@cheetah.cadsoft.de...

I am getting the Stop Mask error on DRC because the silk screen layer and

text is overlapping the stopmask. Can I keep this and send to board

manufacturer, for automated assembly (maybe without silkscreen on the

board) or should I correct? I would be a big trouble to correct.

If you don't need the silkscreen, just disable the values,names and place

layers when running DRC and leave out the silk process in the CAM.

IMHO silkscreen does more damage than good, unless you have very good

reasons to have it.

I do high density stuff, and there is just not space for silkscreen. I do

not really want to waste time positioning stuff that have no use. The

manufacturer has told me they don't need it.

Also note that silkscreen may cause problems even if DRC does not detect

errors. Say you have a very flat or small smd component and some silk under

it, you may have problems getting both ends touching the pcb at the same

time, cause the silk build slightly up under it.

Thiago Henrique wrote on Sun, 31 January 2010 16:53

I see. Please check the picture attached. I resized the silkscreen

frame, it

is inside the Stop Mask. What do you suggest? To resize the stop mask

also?

The holes in your solder mask do look quite large.  However, the numbers in

the middle of each pad are the more serious problem.  Those should

definitely not be on the silkscreen.  Put them in the tDocu layer if you

really want them in the board drawing.

--

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Morten Leikvoll wrote on Mon, 01 February 2010 03:46

IMHO silkscreen does more damage than good, unless you have very good

reasons to have it.  I do high density stuff, and there is just not

space for silkscreen. I do not really want to waste time positioning

stuff that have no use.

There are certainly issues with silkscreen and high density boards, but to

make a blanket statement that silkscreen "does more damage than good" is

just silly and possibly misleading to newbies.  Silkscreen can be very

useful in decreasing human error.  Even if the entire assembly process is

automated, the silkscreen can still help later in part identification,

inventory, installation into the bigger system, etc.  It may not do much

for your specific case, but there are many designs where it does help,

which probably include the majority of boards designed by the people here.

--

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silk is also important in troubleshooting, but oh yeah, we never have

that problem.

seriously, thiago, as olin mentioned, almost all board houses will

remove the silk from offending areas these days, check with yours

regarding their policy. it's easy to miss small areas.

do we have a ULP that does this?

"Gary Gofstein" <nospam@use.forum.net> escreveu na mensagem

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silk is also important in troubleshooting, but oh yeah, we never have that

problem.

 

seriously, thiago, as olin mentioned, almost all board houses will remove

the silk from offending areas these days, check with yours regarding their

policy. it's easy to miss small areas.

 

do we have a ULP that does this?

I see. Well this is my first board that is not for "amateur" purposes. I'll

have it fabricated and assembled in scale, and I can't afford running into

mistakes. The DRC error scare me, like something could go wrong during

fabrication/assembly process. I just want to get rid of the errors and make

it pretty easy to the PCB house to understand the board. I would appreciate

some tips from someone who has boards manufactured all the time.

Regards,

Thiago Henrique Rodrigues wrote:

"Gary Gofstein" <nospam@use.forum.net> escreveu na mensagem

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silk is also important in troubleshooting, but oh yeah, we never have that

problem.

 

seriously, thiago, as olin mentioned, almost all board houses will remove

the silk from offending areas these days, check with yours regarding their

policy. it's easy to miss small areas.

 

do we have a ULP that does this?

 

I see. Well this is my first board that is not for "amateur" purposes. I'll

have it fabricated and assembled in scale, and I can't afford running into

mistakes. The DRC error scare me, like something could go wrong during

fabrication/assembly process. I just want to get rid of the errors and make

it pretty easy to the PCB house to understand the board. I would appreciate

some tips from someone who has boards manufactured all the time.

 

Regards,

 

 

Why don't you generate gerbers and submit the gerber set to

www.freedfm.com.   Their tools will review your files and send you an

email w/ what they deem to be pcb manufacturing problems.   If there are

no "show stoppers" then chances are that Advanced Circuits could

manufacture your board w/o difficulty.    Note that the automated tools

do not look for potential assembly problems however....like very sort

component in between two very tall ones.

Jim