PCB Libraries Forum : Blind Via With Smaller Solder Mask Opening https://www.PCBLibraries.com/forum/ Wed, 15 Apr 2026 07:12:55 +0000 Thu, 19 Sep 2013 07:44:17 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 360 https://www.PCBLibraries.com/forum/RSS_post_feed.asp?TID=1110 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[Blind Via With Smaller Solder Mask Opening : It was in San Diego, CA about...]]> https://www.PCBLibraries.com/forum/blind-via-with-smaller-solder-mask-opening_topic1110_post4364.html#4364 Author: Tom H
Subject: 1110
Posted: 19 Sep 2013 at 7:44am

It was in San Diego, CA about 10 years ago. I don't remember their name. They said it was no big deal.
 
I'm sure you can Google an answer.
 
]]> Thu, 19 Sep 2013 07:44:17 +0000 https://www.PCBLibraries.com/forum/blind-via-with-smaller-solder-mask-opening_topic1110_post4364.html#4364 <![CDATA[Blind Via With Smaller Solder Mask Opening : Hi Tom, Do you remember the...]]> https://www.PCBLibraries.com/forum/blind-via-with-smaller-solder-mask-opening_topic1110_post4362.html#4362 Author: NB168
Subject: 1110
Posted: 19 Sep 2013 at 2:05am

Hi Tom,
 
Do you remember the assembly shop that you sent to for touch up? Possible to send the contact please. Many thanks.
 
Best Regards,
NB.
]]> Thu, 19 Sep 2013 02:05:41 +0000 https://www.PCBLibraries.com/forum/blind-via-with-smaller-solder-mask-opening_topic1110_post4362.html#4362 <![CDATA[Blind Via With Smaller Solder Mask Opening : All vias under BGA&#039;s need...]]> https://www.PCBLibraries.com/forum/blind-via-with-smaller-solder-mask-opening_topic1110_post4358.html#4358 Author: Tom H
Subject: 1110
Posted: 18 Sep 2013 at 7:04pm

All vias under BGA's need to be "Tented" with solder mask to prevent solder bridging under the component.
 
I did the same thing once and the bare boards got to assembly and rejected. Tried to go back to the fabrication shop but they turned me down saying that the solder mask has been cured and there was nothing they could do.
 
So I contacted a different assembly shop and they said "No problem, bring in the bare boards and we'll touch up the exposed vias with a special mask material that we'll manually apply and oven cure".
 
I only wish I would have written down the name of the mask material, but I didn't because I knew from that day forward I would never have exposed vias under a BGA. It cost extra and delayed the delivery, but I did not have to rebuild the boards.
 
]]> Wed, 18 Sep 2013 19:04:38 +0000 https://www.PCBLibraries.com/forum/blind-via-with-smaller-solder-mask-opening_topic1110_post4358.html#4358 <![CDATA[Blind Via With Smaller Solder Mask Opening : Hi, Have received a design file...]]> https://www.PCBLibraries.com/forum/blind-via-with-smaller-solder-mask-opening_topic1110_post4357.html#4357 Author: NB168
Subject: 1110
Posted: 18 Sep 2013 at 6:04pm

Hi,
 
Have received a design file from customer for layout modification, this is a HDI designer and the previous designer has created blind via (L8-L7) for the 8 layers board with small solder mask opening. The drill for this blind via is 0.1mm, pad is 0.3mm and the solder mask opening is 0.2mm. These vias are under the BGA.
 
Any idea what is the intention of previous designer of opening the solder mask under the BGA, now the board is fabricated and we are worry of short under the BGA and need to re-do the fabrication with the solder mask close and affected our schedule.Confused
 
Any suggestion on rework on the existing board or the rationale of the open solder mask of the previous designer.
 
Thanks,
NB
 
]]> Wed, 18 Sep 2013 18:04:03 +0000 https://www.PCBLibraries.com/forum/blind-via-with-smaller-solder-mask-opening_topic1110_post4357.html#4357