Ralph, I do not have a copy to hand but, I remember that IVF in Sweden did a detailed report about this issue some 8 years ago. Maybe Per-Erik Tegehall is looking in?? The conclusion was that using the right frequency made little or no difference with immersion up to around 8 hours or something. Kinda prolonged cleaning regime that would be! The other issue is that some of the newer solvents require substantially more USC power to achieve cavitation. I also recall from the British CFC Elimination Project run by Colin Lea of our NPL, that there was no appreciable difference in cleaning results between high pressure spraying and USC - spraying (which in those days employed far lower pump power than today) just got the vote. Regards, Graham Naisbitt [log in to unmask] Concoat Ltd Phone: +44 1276 691100 Alasan House Fax: +44 1276 691227 Albany Park CAMBERLEY GU15 2PL UK -----Original Message----- From: Vaughan, Ralph H <[log in to unmask]> To: 'TechNet E-Mail Forum.' <[log in to unmask]>; 'Graham Naisbitt' <[log in to unmask]> Date: 24 March 1999 16:22 Subject: RE: [TN] RF PCMCIAs and Cleanliness >Just a general inquiry on this cleaning issue: A while back when cleaning >alternatives was the subject of the day, the use of ultrasonics was one of >the viable candidates. Discussions always went like," ...ultrasonic >cleaning works great, but..." and then the stuff about possible part damage >scared everybody off. I always thought somebody would do a study >demonstrating liklihood of damage, or come up with a system that would be >safe for most parts, but the technology seems to just be sitting in the back >of the bus, not banned but not really used either. Are there actual >instances where responsible use of ultrasonics affected an assembly's >reliability? > >Ralph Vaughan > >> ---------- >> From: Graham Naisbitt[SMTP:[log in to unmask]] >> Reply To: TechNet E-Mail Forum.;Graham Naisbitt >> Sent: Wednesday, March 24, 1999 4:11 AM >> To: [log in to unmask] >> Subject: Re: [TN] RF PCMCIAs and Cleanliness >> >> Mike >> >> If this debate was 12 months old, I would have agreed with you 100%. >> >> However, if you are going to deal with BGA, MicroBGA, Flip-Chip and other >> COB packaging, then it becomes necessary to reduce the surface tension of >> the water to enable it to penetrate beneath such components. This means >> adding surfactants (wash chemistry) in the wash stage. Yes, I know that >> this >> renders a pure aqueous machine redundant, unless it is equipped with >> extended wet isolation and a separate wash stage. >> >> Removing OA residues particularly BGA is crucial when dealing with safety >> critical or high reliability devices. However, it is also crucial to >> ensure >> that the - dissolved or solubalised - contaminants are then adequately >> removed. >> >> As a suggestion to those who have concerns, make up (or I can help with) a >> coupon that includes the more difficult component types you are using or >> are >> proposing to use. Process them in parallel with your product and then run >> SIR testing using the latest methods - frequent monitoring and voltage >> gradient - if you have good results with pure OA or indeed no-clean, then >> no >> problem. You might also take a peek under some of them. >> >> From the evidence we have, I think you will need to adapt your process >> this >> way. Yeah! RMA could now be re-used - what goes around, comes around! >> >> Regards, Graham Naisbitt >> >> [log in to unmask] >> >> Concoat Ltd Phone: +44 1276 691100 >> Alasan House Fax: +44 1276 691227 >> Albany Park >> CAMBERLEY >> GU15 2PL UK >> -----Original Message----- >> From: McMonagle, Michael R. <[log in to unmask]> >> To: 'TechNet E-Mail Forum.' <[log in to unmask]>; 'Graham Naisbitt' >> <[log in to unmask]> >> Date: 23 March 1999 14:22 >> Subject: RE: [TN] RF PCMCIAs and Cleanliness >> >> >> >Graham, >> > Thanks for the reference, it provides some interesting >> >information. However, it is based on cleaning RMA fluxes, not OAs. Most >> >non-military assembly processes are using OA chemistries with straight >> >aqueous processes, or have moved towards no-clean. A robust high >> >pressure inline aqueous cleaner should handle most all low-profile >> >components soldered with OA chemistries, without the use of wash >> >additives. However, each assembly must be evaluated on its own merits >> >and tested under production conditions to assure adequate cleanliness >> >for the specified end-use environment. >> > >> >Mike McMonagle >> >PCA Process Engineering Supervisor >> >K*Tec Electronics >> >1111 Gillingham Lane >> >Sugar Land, TX 77478 >> >(281) 243-5639 Phone >> >(281) 243-5539 Fax >> >[log in to unmask] >> > >> >> -----Original Message----- >> >> From: Graham Naisbitt [SMTP:[log in to unmask]] >> >> Sent: Tuesday, March 23, 1999 6:34 AM >> >> To: [log in to unmask] >> >> Subject: Re: [TN] RF PCMCIAs and Cleanliness >> >> >> >> John >> >> >> >> It would appear that no-one answered your question. So if it is not >> >> too >> >> late... >> >> >> >> How clean is clean is a great big topic. There was an interesting >> >> article in >> >> the Feb 99 issue of Precision Cleaning magazine written by people at >> >> Lockheed Martin that covers this subject well. This is a USA journal >> >> and if >> >> you need details, ask me. >> >> >> >> They basically found that with low stand-off components, you MUST use >> >> wash >> >> chemistry to lower surface tension of the water to get it underneath >> >> AND >> >> remove the contaminant. However, it involves power - (wash pressure) >> >> as well >> >> as solvent power (wash chemistry). >> >> >> >> Regards, Graham Naisbitt >> >> >> >> [log in to unmask] >> >> >> >> Concoat Ltd Phone: +44 1276 691100 >> >> Alasan House Fax: +44 1276 691227 >> >> Albany Park >> >> CAMBERLEY >> >> GU15 2PL UK >> >> -----Original Message----- >> >> From: John Gulley <[log in to unmask]> >> >> To: [log in to unmask] <[log in to unmask]> >> >> Date: 12 March 1999 17:24 >> >> Subject: [TN] RF PCMCIAs and Cleanliness >> >> >> >> >> >> >Address, >> >> > >> >> >We have an application where we are using OA Flux and Paste to >> >> process >> >> >RF PCMCIAs. The PCAs are thoroughly cleaned prior to test. I'm >> >> still >> >> >having test issues with RF PCMCIAs. >> >> > >> >> >If I remember correctly, I read an article that discussed cleanliness >> >> of >> >> >PCAs that are RF. If the PCA is not thoroughly cleaned, the organics >> >> >will wreak havoc on the RF tests. There are chemistries (saponifers) >> >> >available that will reliable remove the excess organics and provide >> >> >enough cleanliness to pass RF testing. >> >> > >> >> >CAN someone please provide some more light onto this issue or give me >> >> a >> >> >direction to pursue, e.g., contacts. Thanks. >> >> > >> >> >John >> >> > >> >> > >> >> > >> >> > >> >> > >> >> >> >> ################################################################ >> >> TechNet E-Mail Forum provided as a free service by IPC using LISTSERV >> >> 1.8c >> >> ################################################################ >> >> To subscribe/unsubscribe, send a message to [log in to unmask] with >> >> following text in the body: >> >> To subscribe: SUBSCRIBE TechNet <your full name> >> >> To unsubscribe: SIGNOFF TechNet >> >> ################################################################ >> >> Please visit IPC's web site (http://www.ipc.org) "On-Line Services" >> >> section for additional information. >> >> For technical support contact Hugo Scaramuzza at [log in to unmask] or >> >> 847-509-9700 ext.312 >> >> ################################################################ >> > >> >> ################################################################ >> TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c >> ################################################################ >> To subscribe/unsubscribe, send a message to [log in to unmask] with >> following text in the body: >> To subscribe: SUBSCRIBE TechNet <your full name> >> To unsubscribe: SIGNOFF TechNet >> ################################################################ >> Please visit IPC's web site (http://www.ipc.org) "On-Line Services" >> section for additional information. >> For technical support contact Hugo Scaramuzza at [log in to unmask] or >> 847-509-9700 ext.312 >> ################################################################ >> > ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################