steve, you are dealing with the cleanliness GURU. The GURU as below. > Steve > > Just a few thoughts before the gurus speak. If you do an extraction > conductivity test, as you suggest, what will you be measuring after > soldering? The residues from your no-clean flux, not the cleanliness of > your assembly. Are these important? Possibly, but... > > What may be important (depending mainly on your board manufacturer) is > whether the boards are clean before fluxing/soldering/reflow. IMHO, this > is the most important thing to test. > > Personally, for a 'no-clean' process I would not test for ionic > contamination after soldering. Instead, I would rely on a reputable > well-chosen flux and let it go at that. This does not mean you can use > out-dated or contaminated flux/paste or that your housekeeping leaves to > be desired. You will still need good, ordinary, practices. > > FWIW > > Brian > > On 23/06/2017 14:50, Steve wrote: >> I realize that this is an old and continuing subject of debate in the >> industry, but I am interested in the current updated consensus on the >> topic. Specifically, what kind of PCBA cleanliness level should be >> reasonably expected to achieve? >> >> Of course the answer is always "it depends," because that is the >> reality. And the actual acceptance or control level needs to be set >> according to product requirements. But what I am after is slightly >> different: What level of cleanliness would you expect to be readily >> achieved by a good quality manufacturing process under normal >> circumstances? >> >> Some general parameters to narrow down the question: >> >> - Measurement technique bulk solvent (ROSE per IPC TM-650 2.2.25) >> - Pretty normal PCBA design - 0403 components, some through hole, >> nothing really unusual >> - Pretty normal process, RoHS, no-clean. >> - Class 2 PCBA, but high impedance low current battery powered >> application >> - High production volume (>1 million units annually) >> >> I am not aware of anything that has replaced the 1.56/cm^2 "standard." >> but this has been around forever, it seems. Common sense tells me that >> even if a formal standard has not changed general performance might have >> improved, on account of smaller components, tighter board spacing and >> general technological improvements. >> >> What has been your actual experience in this regard? >> >> Thanks in advance, >> Steve >> > >