Hello Pete,

I agree with Dave that RMA and RA type fluxes will easily remove tin oxides and be able to solder to the BGA spheres.  There are several no clean solder pastes that can do the trick, but gel/tacky flux might be a better option.  Using gel flux to solder the BGA to the circuit board rather than solder paste provides a much greater level of available activators to remove the oxide.  This assumes that the BGA spheres have enough solder volume to make an adequate joint.  


Best regards,

Tony Lentz
FCT Assembly
Technical Sales & Support
[log in to unmask]
970-566-0360 Mobile

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
Sent: Wednesday, April 8, 2015 12:22 PM
To: [log in to unmask]
Subject: Re: [TN] 5 year old BGAs

Hi Pete - with an adequate reflow profile and the selection of an adequate flux, not a big deal. Most of today's low residue flux formulations or the "old" RMA type flux formulations will remove 40nm of oxide without any issues.

Dave

On Wed, Apr 8, 2015 at 1:17 PM, Peter G. Houwen <[log in to unmask]>
wrote:

> Dave,
>
> So what is the impact of that 40nm on solderability?
>
> Pete
>


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