Minimum Gang Solder Mask Web

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   Hi, I’d like to understand how work Minimum Gang Solder
Mask Web in SMD Pad Stack Rules

I have these specifications in Component Data

If I use 0.10 mm for the Minimum Gang Solder web mask, I get a
0.83 x 0.40 mm mask, so the web mask = 0.10 mm that is correct

If
I use 0.10 mm for the Minimum Gang Solder web mask, I get a 0.83 x 0.50 mm mask,
hence the web mask. I don't understand why the mask becomes 0.40 mm to 0.50 mm.
I
expected the mask to stay at 0.40 mm for a 0.10 mm web

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yvoren1 Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 07 Jun 2013 Status: Offline Points: 17	Post Options Post Reply Quote yvoren1 Report Post Thanks(1) Quote Reply Topic: Minimum Gang Solder Mask Web Posted: 19 Dec 2023 at 1:17pm
	Hi, I’d like to understand how work Minimum Gang Solder Mask Web in SMD Pad Stack Rules I have these specifications in Component Data If I use 0.10 mm for the Minimum Gang Solder web mask, I get a 0.83 x 0.40 mm mask, so the web mask = 0.10 mm that is correct If I use 0.10 mm for the Minimum Gang Solder web mask, I get a 0.83 x 0.50 mm mask, hence the web mask. I don't understand why the mask becomes 0.40 mm to 0.50 mm. I expected the mask to stay at 0.40 mm for a 0.10 mm web



Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 19 Dec 2023 at 4:35pm
	Are you wondering why the solder mask excess isn’t limited to prevent a sliver instead of increased to fill the sliver?
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yvoren1 Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 07 Jun 2013 Status: Offline Points: 17	Post Options Post Reply Quote yvoren1 Report Post Thanks(0) Quote Reply Posted: 20 Dec 2023 at 6:43am
	Yes, that’s what I would like to know!

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 20 Dec 2023 at 9:57am
	First, setting the solder mask web to 0.10 is overkill. Fabrication shops can easily produce a 0.07 solder mask sliver. Where the Fabrication industry needs is a 0.05 mm solder mask swell and a 0.05 solder mask web. This will ensure a solder mask sliver between every SMD pad stack and eliminate Gang Masking of entire rows of pads. Ask your fabrication shop how accurate is their solder mask application process.
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yvoren1 Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 07 Jun 2013 Status: Offline Points: 17	Post Options Post Reply Quote yvoren1 Report Post Thanks(1) Quote Reply Posted: 20 Dec 2023 at 10:04am
	OK , Some of my fab shop don't want to go under 0.1mm , but now i know how far i can go Thank you Tom!

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 20 Dec 2023 at 10:12am
	There is something you need to know. If your fabrication shop requires a 0.10 mm solder mask sliver, if you don't Gang Mask the row of pads in your PCB library, your fabrication shop will run a check on your Gerber data to find every pad that has a sliver less than 0.10 mm and they will gang mask the row of pads without even asking you. So either you provide the correct data or they will correct your data.
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bab27 Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 01 Sep 2024 Status: Offline Points: 13	Post Options Post Reply Quote bab27 Report Post Thanks(1) Quote Reply Posted: 03 Sep 2024 at 5:58am
	I'm looking for an IPC for these kinds of specification. IPC-7352 Page 34, there is an example with 0.50 mm Pitch SOP with 0.05 mm Solder Mask from copper and 0.075 mm from Solder Mask to Legend (silkscreen). Do you know if there is more information according to the fabrication level, A, B or C about that?

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(1) Quote Reply Posted: 03 Sep 2024 at 8:15am
	I provided IPC-7352 with the silkscreen and solder mask illustration on page 34. IPC (as a standards organization) does not have any guidelines for silkscreen because they don't believe in silkscreen. They're recommendation is "No Silkscreen", but I think that's in reference to mass production boards. As PCB designers we all create prototype boards that require silkscreen for small batches. We recommend a silkscreen line width between 0.12 mm minimum, 0.15 mm nominal and 0.20 mm maximum. IPC has no rules or guidelines on solder mask. The current range for solder mask annular ring in the electronics industry (from component manufacturers recommendations) is between 0.05 mm minimum, 0.07 mm nominal and 0.10 mm maximum. The gap between the silkscreen and solder mask would be the tolerance of the application of both, which is 0.07 total. You don't want any silkscreen encroaching in the solder mask removal area. If there is silkscreen in the solder mask removal area, the fabrication shop will automatically trim it off for you.
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bab27 Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 01 Sep 2024 Status: Offline Points: 13	Post Options Post Reply Quote bab27 Report Post Thanks(1) Quote Reply Posted: 11 Sep 2024 at 7:40am
	Thank you very much for your reply.