Thanks folks for the responses. Let me add a little more detail.
The flux is water soluble and we intend to wash it off. We want a measure
of how well we're doing that.
I should be clearer that the flux is flux-paste, stencil printed, 7-mil
square, for flip chip bumps only.
There are no other components at all. Not much of an assembly.
Glenn
-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Friday, May 23, 2003 9:57 AM
To: [log in to unmask]; Pelkey, Glenn R
Subject: Re: [TN] ROSE for Flip Chip
Glenn,
This argument is about as pointless as arguing temporal theories of
Schwartzeneggar movies.
Either way, you are going to get a pointless result. If you use the die
surface only, you are assuming that you will have no contribution from the
rest of your assembly. Bad assumption. If you use the board surface, then
you will swamp out what little signal you have by averaging over a much
larger surface area. You should use a different approach than ROSE. It
was NEVER meant for something like flip chips.
Doug Pauls
Rockwell Collins
Glenn Pelkey
<glenn.r.pelkey@M To:
[log in to unmask]
AXTEK.COM> cc:
Sent by: TechNet Subject: [TN] ROSE for Flip
Chip
<TechNet@listserv
.ipc.org>
05/23/2003 08:59
AM
Please respond to
"TechNet E-Mail
Forum."; Please
respond to
glenn.r.pelkey
Hi Technetters,
My buddy and I have a disagreement on using Resistivity of Solvent
Extract (ROSE) for measuring cleanliness on a Flip Chip board. So, we're
throwing it to league of experts on this forum for feedback
Here's the story: The board and assembly are very simple. One
flip chip die at about 0.002 square inches and one board about 0.490 square
inches. Flux is applied only to the flip chip die, reflowed, and DI inline
washed.
Here's the disagreement: I say use 2X the surface area of the die
for the calculation. My good friend says use 2X the board surface. Of
course, you can see one number is much higher than the other in ug/sq inch
NaCl equiv. My logic for using only the die area is to understand the
process cleanliness at that location only, but I recognize the entire board
surface could be cross contaminated in some manner. We also loaded the
machine with 32 of these units to get something measurable. When we only
put 4 in, nothing showed up, but the smallest entry for surface area is 0.1
square inches.
Thanks for your input!
Glenn
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