Good morning Steve,

Yes, It Depends.  IPC sends people my way when they have questions in this
area.
What you want are two documents
IPC-948095  Cleanliness Requirements for Pretty Normal Processes
IPC-948096  Cleanliness Requirements for Weird Ass Processes.

Just kidding.

Over the last two years, I have been leading a small team of SMEs for the
J-STD-001 committee on what should replace ROSE testing for the next
generation of ionic residue testing.  Although we missed the window for the
upcoming G revision, I believe that the committee will review our proposal
as an Amendment activity, though I have not yet discussed this with the
J-STD-001 leaders.  The draft of our proposal and an associated white paper
explaining the proposal, was turned in to the committee earlier this
month.  It should be circulated sometime this summer.


Doug Pauls
Principal Materials and Process Engineer
Rockwell Collins

On Fri, Jun 23, 2017 at 6:50 AM, Steve <[log in to unmask]> 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
>