Walter Thanks for the explanation. However, it does lead to a question: if organic compounds such as oxyfluorocarbons are deposited on conductors and can deteriorate the solderability, would this not also destroy the "bondability"? I can also see that reducing gases could deoxidise metals, but they would possibly not break down the F-C bond??? Brian "Dr.Walter Schmidt" wrote: > Brian > > Plasma can also be used with desoxidizing gases, like hydrogen, methane > and others. In addition inert gases like argon can be used to "sputter" > off the surface and clean it. In some special cases, even the short UV > photons, generated within the plasma when He is used as a gas, can help > to modify a surface. > > Plasma cleaning is widely used in the hybrid world to improve > bondability of metal surfaces. > > Solderability is adversely affected by plasma, when organic molecules > are formed within the chamber and they deposit on the surface. When CF4 > is used, for instance, together with organic substrates and water is > released from the organic material in vacuum, very stable C-F-O > molecules may be formed. > > Walter > > Brian Ellis schrieb: > > > > Mike > > > > Was this gold-on-gold bonding, aluminium or what? I'm not an expert on plasma cleaning, but I was > > given to understand that an oxidising gas is used which converts organics to CO2 and H2O. As O, as > > opposed to non-ionised O2, is a violently reactive substance, this reaction occurs easily, but, > > equally, M + O > MO (where M is a base metal). Or am I up the pole? > > > > Brian > > > > Michael Fenner wrote: > > > > > I was peripherally involved in this some years ago with a company looking to improve wire > > > bonding and cleanliness generally. A half an eye was kept on solderability "just in case." > > > They noted that the type of plasma cleaning, had a noticeable effect on whether surfaces became > > > more or less wirebondable, but where the work became more bondable there was no change in > > > solderability. We put this down to the fact that whether there was a little oxide, non or a > > > lot the flux had more than adequate capability to remove it anyway. However if the plasma type > > > chosen made wirebonding worse it also screwed solderability. We put this down to the fact that > > > the plasma was chewing off organics and then allowing them to be re-deposited. As this was a > > > side issue and not the object of the exercise it was not investigated and remained a surmised > > > comment in the footnotes. > > > > > > Hope this helps. > > > > > > Mike > > > > > > ----- Original Message ----- > > > From: Brian Ellis <[log in to unmask]> > > > To: <[log in to unmask]> > > > Sent: Thursday, April 27, 2000 11:41 AM > > > Subject: Re: [TN] Solderability > > > > > > > Raj > > > > > > > > No, but it's an interesting thought. I should imagine that some types of > > > > plasma could be quite active towards oxidising base metals. > > > > > > > > Brian > > > > > > > > Rajkumar wrote: > > > > > > > > > Hello everyone Hope everyone had a good easter break. I need to know, > > > > > if anyone is working on solderability degradation after plasma > > > > > cleaning? 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