Wayne:

To my knowledge IPC standards have never specifically addressed a quantity limit (accept/defect) of flux (whether cleanable or no-clean) that can be used in the manufacturing process. The old engineering answer of "it depends" applies. The only requirement established has been on the cleanliness requirements. 

Gregg 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - IS
Sent: Monday, November 05, 2012 3:50 PM
To: [log in to unmask]
Subject: [TN] Limits on flux residue

Is there a spec somewhere which limits the amount of residue allowed for no clean processing?  I just saw a board where a BGA was about 70% "underfilled" by flux residue.  No, this was not a flux/underfill product!  A quick look at JSTD-001 Section 8 didn't seem to have specific guidance on this condition.

Wayne Thayer

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