Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


No Clean and Underfill

Views: 3789


CL

#58257

No Clean and Underfill | 4 March, 2009

Good Afternoon Everyone, I have a customer who is inquiring as to the use of a no clean solder paste on their RoHS assembly. We are currently building this with OA, cleaning and then underfilling the QFN, BGA comonents after a sucessful ICT. Does anyone have experience with assembly using no clean with an underfill? Any comments or suggestions would be greatly appreciated.

Thanks

Chris

reply »

#58261

No Clean and Underfill | 4 March, 2009

Underfill epoxies may be classified into major groups [Capillary Underfill Manufacturing Development and Characterization for 2nd Level Electronic Interconnect Processes; B Salom�n; University of Puerto Rico, Mayaguez Campus; Dec 2004]: * Capillary. * Fluxing (No-Flow) - not used for 2nd level interconnect applications. * Removable (Repairable) � repairable underfill. * Corner Bond � underfill placed only at the corners of the component.

Here are some articles at Daan Terstegge's excellent jump site: http://www.smtinfo.net/Db/_Underfilling.html

reply »


CL

#58265

No Clean and Underfill | 5 March, 2009

Thanks Dave

reply »

#61410

No Clean and Underfill | 19 March, 2010

No clean pastes leave more flux residues. These can result in void formation and inhibtion of underfill curing. Selection of an underfill that is compatible with the flux residue is important.

One company that has written about the effect of flux residues on underfill is Zymet.

reply »

#61411

No Clean and Underfill | 19 March, 2010

Be carefull if you go to no clean. Or be prepared from complaints from the test department regarding their ICT pins getting dirty.

reply »

HeatShield Gel- thermal PCB shield during reflow