That's a good point. From a PCB shop's view, allowing the vias to be plated shut means we have one last thing to worry about when checking final hole sizes. The other possibility that comes to mind is that if you require LPI solder mask, we can't coat over vias. The mask runs through the holes and makes a mess. The solution, as was mentioned here, would be to plug the holes. However, this adds a couple production steps, thus increasing the cost. I guess it depends on what you want. Higher cost but better product, or lower cost and possible chemistry entrapment. Our customers are typically government contractors. They usually have a contract already in place and are looking for cost savings. (Within reason, of course.)

Karl

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David Greig
Sent: Thursday, April 26, 2007 11:39 AM
To: [log in to unmask]
Subject: [BULK] [TN] "plated shut vias"
Importance: Low


Hi List,
 
Yet again I've come across fabrication notes on other pcb designers notes that specify that thru board via's may be plated shut.
 
Is there any historical reason for this, or is it just hysterical?
 
I would be rather concerned to see a closed via that is neither blind or filled, mental images of trapped process chemistry etc.
 
Best Regards
 
David Greig
______________________________
 
GigaDyne Ltd
5 Albany Business Centre
Gardeners Street
Dunfermline KY12 0RN
United Kingdom
t: +44 (0)1383 624 975
www.gigadyne.co.uk
______________________________
 

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