Ask Helena & Leo

Question: I am reviewing IPC-5704, and have a question. When reviewing table 4-1, the chloride limit is 0.75 ug/cm2, which converts to 4.4 ug/in2, however; IPC 6012 still has the board cleanliness limit for sodium chloride as 1.56 ug/cm2 (10.06 ug/in2). Granted, that is supposed to be before solder mask application, but it can be confusing to industry customers. Does IPC plan on revising the 6012 cleanliness limits, or at least point out the difference is before/after solder mask application, on the next revision of 6012?

Answer: Just going through those two documents, IPC-5704 and both Rev D and Rev C of IPC 6012, and both revisions of 6012 mention:

3.9. The contamination level shall not be greater than an equivalent of 1.56 μg/cm2 of sodium chloride” while the 5704 document mentions the .75mg/cm2″

So, yes there is some confusion between the two documents, which should be address by the 6012 committee.

The latest document Rev E comments has not changed the requirements, so I’ll send information to the IPC to look at the conflict. I believe this to be a synergy condition which should be easy to correct.

I would also make sure the customer contract calls out the correct document to be followed to make sure the correct numbers are used.