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

>