Victor,
We use MasterPrep all the time and don't see the problem you are referring to. As Wade indicated if there is separation between your sample and mounting material, or for that matter if you have lots of voids in the solder joints you will trap water and polishing compound in the separation or voids that well come out slowing and mess you nicely polished surface up.
Regards,
George
George M. Wenger
Reliability / FMA Engineer
Base Station and Subsystems Group
Andrew Corporation, 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of McFaddin, Wade
Sent: Monday, April 25, 2005 4:51 PM
To: [log in to unmask]
Subject: Re: [TN] Lead Free, Ball Grid Array, solder bump cross section
Hi Victor,
We use a colloidal silica solution (0.05 micron) for our final polish. We
polish for about one and a half minutes, with the final half minute running
water on the cloth (Buehler's micro-cloth) and cross-section. This cleans
the cloth and the cross-section mount of the colloidal solution. We then
rinse just the cross-section mount again with water and then quickly rinse
with alcohol (IPA) and blow dry with nitrogen and wipe lightly with a cotton
ball. This usually gives us a clean, stain free surface. However, if you
have pull-away (separation) of your mounting epoxy to the sample surface, it
can be very difficult to get all the water and polishing solution out of the
separation area.
Hope this helps.
Wade McFaddin
Nextek Inc.
-----Original Message-----
From: Victor G. Hernandez [mailto:[log in to unmask]]
Sent: Monday, April 25, 2005 1:48 PM
To: [log in to unmask]
Subject: [TN] Lead Free, Ball Grid Array, solder bump cross section
Fellow TechNetters:
I have conducted many of LF solder bump cross section and final
polish is conducted with a Buehler Masterprep
Polishing Suspension Alumina 0.05 microns. Micro craves, epoxy
shrinkage/voids, on the sample surface retain
the polishing compound which contaminate the surface appearance. This
step can cause staining and/or water
marks on the bulb solder prior to mid range magnification examination
with inverted stage microscope.
Can some one recommend a LF chemical etchant that I can replace the
alumina step in my process?
Victor,
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