i did say this quite right previously
s.b.
a neg expansion which would result in an opening a little larger or same size as the hole size
ds
_______________________________________________________________________ Integrated Controls, Inc. Tel: 415-647-0480 EXT 107 2851 21st Street Fax: 415-647-3003 San Francisco, CA 94110 www.integratedcontrolsinc.com
Dennis Saputelli wrote:
yes i think 'covered' is more precise term too when using LPI
a side note:
when wanting 'covering' of vias with larger size holes and using LPI mask don't use the protel 'tenting' feature
use a negative expansion a little bit larger than the hole size or the same size as the hole
this keeps the LPI from flowing excessively into the hole
i don't know the exact size at which one should start doing this but i have made a rule of thumb of > 28 mils
Dennis Saputelli
_______________________________________________________________________ Integrated Controls, Inc. Tel: 415-647-0480 EXT 107 2851 21st Street Fax: 415-647-3003 San Francisco, CA 94110 www.integratedcontrolsinc.com
Kulajew Waldemar wrote:
Dennis, see my comments below.
-----Original Message----- From: Dennis Saputelli [mailto:[EMAIL PROTECTED] Sent: Tuesday, January 11, 2005 9:03 PM Subject: Re: [PEDA] Tenting Phenomenon (Is it riskless)
<<---snipp-->>
but the fab shop was quibbling over the meaning of the term 'tenting'
(they probably got burned once)
'tenting' seems to imply that the hole is guaranteed blocked and gas tight, which at certain dimensions i guess can only be done with dry film
when they use the common LPI mask and the protel gerbered 'tented' vias they described the result as 'covered' vias
<<---snipp-->>
had the same discussion with our fab some time ago. They usualy
have customers which needed 'tenting' for PCB that are tested
with an incircuit tester. ICT mostly use vacuum to hold the PCB down. Therefore the vias have to be 'guaranteed blocked and gas
tight'.
Perhaps that is why they use the termination 'covered' for what
we call 'tented'?
Regards,
Waldemar
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