Rudolph, You have an interesting case. Did the outside lab you used interpret the results for you? If so, what did they say? I saw many such cases when I was at CSL. I suspect that the reason that you are seeing the residue levels jump around so much is due to your bare boards. If you can trust your flux and paste vendors, and you are truly using halide free materials, then the only source of these residues is prior to entry into your assembly operation. In the scenario that you give, it is not likely that you are using the same test sample for extraction at the different points of the assembly process. You are probably using different assemblies on a sample basis. Therefore, you may have differing bare board cleanliness levels. If you are dealing with multiple vendors, I can almost guarantee that you will get different residue levels on incoming boards. I presume that all of the boards are coming in tin-lead coated. HASL fluxes and fusing fluids generally come in one of three flavors: high in chloride (e.g. HCl), high in bromide (HBr), or high in both. And I can just hear Brother Ellis warming up the keyboard to straighten me out on this score. Anyway, if the post-HASL or post-fusing cleaning process is not adequate to remove the HASL flux, or the laminate/solder mask absorbs the flux or fusing fluid, then you get bare boards with high levels of chloride and bromide. It is not unusual for a high volume fabricator, such as Photocircuits or Sanmina, to have a chloride-based HASL line running in parallel to a bromide-based HASL line, both of which may be producing your bare boards. Therefore, in one pack of bare boards, you can have a mix of high chloride and high bromide. An even wider mix in residues if you have multiple vendors. I once worked with a vendor with 20 different board sources. Imagine the mix of residues there. It is normal for bromide levels to increase with each exposure to reflow temperatures. Such exposure tends to make the laminate and solder mask more porous, so more flame retardant bromide can be extracted in the ion chromatography analyses. I recognize your customers cleanliness spec as CSL's recommended guidelines for a no-clean assembly operation. A value of 7 for bromide suggests to me that you are using either CEM laminate or polyimide, which have lower amounts of added bromide flame retardant. The bottom line is that the residue levels are probably not jumping around due to your assembly processes, but are due to the varying condition of the boards going in to your process. You ask the question of whether your customer's cleanliness spec is reasonable for a no-clean assembly process. Since I had a large part in developing that recommended cleanliness level, OF COURSE it is reasonable. Brilliantly written. Impeccible data. Sage advice. As Graham Naisbitt might say, "All that rot". If you have other questions, post 'em. I'll give it another shot. Doug Pauls Rockwell Collins I can just hear the incoming rejoiner coming from Cyprus. How is the weather there today Brian? --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------