Hi Steve - We use a number of "bga style" connectors where there is a
solder charge/preform on the connector which is designed to combine with
the solder paste deposit creating sufficient solder volume and good solder
joint integrity. I am not familiar with the having these types of
connectors with "dried flux" - flux has a shelf life so the manufacturer's
comment doesn't make much sense. From a practical point, the flux in the
solder paste deposit is doing the bulk of the oxide scrubbing action so
dried flux contribution is most likely a moot point. But - the fact that
the manufacturer did not acknowledge the possible shelf life issue is
dis-concerning.

Dave Hillman
Rockwell Collins
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On Thu, Aug 24, 2017 at 1:11 PM, Steven Kelly <[log in to unmask]> wrote:

> Hi All,
> I have a new hi-density BGA connector I am trying to assemble. When the
> supplier makes the connector they "solder balls onto the pin" (lead free).
> We see dried flux on the balls and when we solder the connector we are
> getting a few joints with head in pillow. The connector manufacturer says
> the dried flux is not an issue - is this true? Thanks. Steve Kelly
>