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 --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------