| Author |
 Topic  |
|
|
Benno
Netherlands
79 Posts |
 Posted - 21 Jul 2013 : 17:43:44
|
Hi,
I think I have created an issue somehow in my setup that I do not understand. I just send a board to a productionhouse and viewing their production setup I see that there is no solder-resist between the pads (at least on-screen).
So I rechecked the Gerbers I have send, there is a soldermask across all the pads, where I would have excpected a mask slightly bigger then the SMD pad on the resist layer. As far as I know resist is negative?
I checked the components layer setup in technology file with the footprint open in the editor. There the resist is setup as absolute +0.127. Paste mask is setup absolute -0.127. In this case it was a modified footprint from my Microchip library. I modified the standard MSOP10 to comply with the info on the datasheet for this component (LT3440).
I also have an ATTiny processor on this board, that seems to get a correct solderstop mask. This is a SOIC20-W_MC footprint. If I open that component (footprint) in the editor and look at the Technology file layer setup the Mask is setup as ansolute +5.
In my design file I use standard technology file, and in the layer setup it is also absolute +5.
Does anyone have a clue about what I am missing? I still use EasyPC 15 and could not find the right pointer to my problem in the help or the manual.
I need to create a number of new components shortly, among them small connectors where I really need a soldermask between the pins.
Any info is welcome.
Thanks.
Benno
|
|
|
Iain Wilkie
United Kingdom
1015 Posts |
Posted - 21 Jul 2013 : 20:21:47
|
If the solder mask is +5 thou in you design and the gap between pads is 10 thou or less, then there will be no resist between, is this the case ?
To be quite honest don't use the inbuilt resist and paste masks, generate your own layers and this means you can see exactly what these layers look like from within the pcb editor.
Iain |
 |
|
|
edrees
United Kingdom
779 Posts |
Posted - 22 Jul 2013 : 09:10:08
|
| As Iain says, but view the gerbers you produce with a 3rd party gerber viewer like Viewmate or GC Preview. You can then independently verify that the resist and paste layers are what you expect. |
|
|
|
Benno
Netherlands
79 Posts |
Posted - 22 Jul 2013 : 22:20:04
|
Hi Ed and Iain,
I do check my gerbers, but in this case was too fast sending them to production. I also never had issues on my soldermask before, probably because most was pth and bigger smd components. That seems to work OK with the standard setup producing gerbers.
Iain, you advise to create an extra layer in my pcb design for the solderstop. What is the best scenario I can use to do that? Is it something I can do when defining my footprints in component editor or is it only possible in the design?
What is your advice when creating a soldermask, how much should I add to the pad?
Is this auto generating issue with soldermask solved in V16? In that case I will buy the update.
Thanks for any advise on these SMD issues. |
|
|
|
Iain Wilkie
United Kingdom
1015 Posts |
Posted - 23 Jul 2013 : 08:30:25
|
To create specific "in editor" resist and paste masks see here (technique 2) http://www.numberone.com/faq.aspx?KB020043
This is much better than letting easy pc do it for you (technique 1) and means you can also easily add exceptions into these masks. The clearance amounts to use on these masks is really up to you and your manufacturer.
Iain
|
|
|
|
Benno
Netherlands
79 Posts |
Posted - 23 Jul 2013 : 11:16:56
|
| Thanks Iain. |
|
|
| |
Topic |
|
Soldermask Issues on some SDM components