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 [log in to unmask] 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 >