Stella:

I have had similar experiences when we switched from an alcohol based flux 
(RMA) to a water based flux (Kester HF1189A).  While the HF1189A is not a 
no-clean material but is a water soluble flux, I believe that you are 
observing the same sizzling and popping of the the board in the solder wave 
which generates solder balls due to the moisture in the flux hitting the 
wave. Alcohol based fluxes dry much quicker allowing the flux to do what its 
supposed to do.

What I found was that I needed to dry out the moisture in the flux without 
overheating the flux. By turning up my air-knife after my foam fluxer I was 
able to apply a thinner amount of flux to the board. I also lowered my 
pre-heat settings and slowed down my conveyor to promote a slighly longer 
drying period for the amount of pre-heat area that I have.  (Note: I am 
considering the purchase of additional pre-heat panels so that I can return, 
at the very least, to my original conveyor speed.) This adjustment virtually 
eliminated the solder ball condition that we were observing. Additional 
adjustments to the solder wave temperature further improved the process to 
the point that our quality was equal or better to that when we ran alcohol 
based fluxes.

Bill Kasprzak  
Moog Inc.
716-652-2000 ext 2507
email --   [log in to unmask]  

***************************************************************************
* 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]      *
***************************************************************************