Posted by Kramski: Sat Sep 16, 2006 5:57 am    Post subject: frontside contaminants

I'm currently handling backside operations (Wirebond, saw, E-test). What are the common practices when cleaning the frontside of the dice? My problem is that when we see some particles, we try to remove it by scrapping them with the vacuum wand tip. I suspect that we are contributing more particles (from the rubber) than actually removing the dirt.

Posted by Jarod: Sat Sep 16, 2006 7:33 am    Post subject:

Have you determined what are these contaminants? (i.e. silicon dust). If its silicon dust, you can check your sawing process esp during washing.

Posted by Techsurfer: Sun Sep 17, 2006 1:12 am    Post subject:

I agree with Jarod. It would be good to identify the contam. If the contam is just ordinary dust particles, then maybe it's better to address the particle count in the cleanroom than pick the contam from the die.

Posted by Jefriz: Mon Sep 25, 2006 12:43 pm    Post subject:

Hi Kramski,

   
I agree with Jarod & Techsurfer, to identify the rootcause of the contaminant. Try the several problem solving techniques in this site.
  
For containment action, you may try using liquid cleaning. If you see the contaminant while the dice are still in wafer frame, you might as well process again in the wafer cleaning area after wafer saw. You might need to use surfactant for better results. If already mounted on leadframe / substrate, try the flux washing process but use only DI water. You can also try using the Ultrasonic cleaner (DI water). If the particle is somewhat microscopic and affects the wirebondability, try plasma cleaning. Or maybe, you might just need to use dry air, evaluate the correct pressure.
 
But you need all to evaluate carefully and observe the packaging integrity deliverables (WPT, BST, DPT and others). Cleaning might be one problem but after cleaning could induced more problem.
 
Best regards, Jefriz