Guenter, How do you check for this on a finished assembly, since the rest of the board is very clean and likely to still pass a general ionic contamination level determination procedure? Is there an approved cleaning method for assembled boards with BGAs, or is no-clean flux the only option? Regards, Karl Sauter ----- Begin Included Message ----- Date: Fri, 7 Mar 1997 14:12:32 +0100 To: [log in to unmask] From: [log in to unmask] (Guenter Grossmann) Subject: Re: Cleaning of BGA Resent-From: [log in to unmask] Hi Poh In my opinion there is no way to clean the solder joints underneath a BGA. You might even worsen the situation because the polymer matrix of the flux residues close to the edge of the BGA will be cracked in a cleaning agent. This solution is washed underneath your BGA and will contaminate the inner row of balls even worse than they where before. Additionally, if you have tracks underneath your BGA, the SIR between the tracks will be affected with all the rubbish you wash under the component. We made trials with QFP's, where we saw that residues are washed underneath the component but that the rinsing operations where not able to remove the sauce accumulating underneath the package. Best regards Guenter Grossmann ----- End Included Message ----- *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************