As far as I know Chromate layer is present on top of the copper foil. 99.9% of probability that this is removed during surface preparation procedures prior to plating and/or before photoresist application. Edward > -----Original Message----- > From: David D. Hillman [SMTP:[log in to unmask]] > Sent: ד מרץ 22 2006 2:03 > To: [log in to unmask] > Subject: Re: [TN] chromates on copper surface (Cr6)? > > Hi Eddie! Just to add to Rudy's comments - any chromate conversion coating > that is Cr+6 based does convert to Cr+3 when damaged (e.g. the self > healing > aspect) but there is always some of the Cr+6 species around. Any chromate > conversion coating that is Cr+6 based is not RoHS compliant. Your supplier > is incorrect unless he/she is supplying a Cr+3 or zero chromate conversion > coating as Rudy described. Qualifying a substitute conversion coating that > is "as good as or better than" a Cr+6 conversion coating is not an easy > task depending on your use environment conditions. Good Luck. > > Dave > > > > Eddie Rocha > <[log in to unmask] > M> To > Sent by: TechNet [log in to unmask] > <[log in to unmask]> cc > > Subject > 03/21/2006 05:56 Re: [TN] chromates on copper > PM surface (Cr6)? > > > Please respond to > TechNet E-Mail > Forum > <[log in to unmask]> > ; Please respond > to > Eddie Rocha > <[log in to unmask] > M> > > > > > > > Was this a tough question? I didn't receive but one > response. Thanks Rudy. > > > > > Eddie: > > Not clear I can "explain" something which is likely > incorrect. > If your vendors start with Cr +6, the likelihood of there > being zero Cr+6 on the foil is near zero... certainly some > of the Cr +6 reacts with Copper metal Cu0 to form Cr+3 and > Cu+2, but all of it? Hah... dream on. > > However, before you go off and begin screaming, I suspect > strongly that some producers of foil may well be switching > from Cr+6 to zero Cr coating... I cannot fathom why > organics could not do as good a job... > > And if there are foil producers who need some technology to > assist this change, contact me... :-) > > Rudy Sedlak > RD Chemical Company > > Eddie Rocha <[log in to unmask]> wrote: I understand that > copper foils are protected with chromates > (Cr6) prior to producing laminate. Since this is an RoHS > banned substance I need to understand why all my laminate > suppliers have certified their material to be RoHS > compliant. > > One supplier responded by stating that Cr6 is reduced to a > state of Cr3 or Cr0 which is not a restricted substance. > > Can somebody explain how it goes from a state of Cr6 to one > of the reduced states and why sometimes Cr3 versus Cr0? > > > Thank you, > Eddie Rocha > > --------------------------------------------------- > Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for > additional information, or contact Keach Sasamori at > [log in to unmask] or 847-615-7100 ext.2815 > ----------------------------------------------------- > > > > --------------------------------- > Brings words and photos together (easily) with > > --------------------------------------------------- > Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for > additional information, or contact Keach Sasamori at > [log in to unmask] or 847-615-7100 ext.2815 > ----------------------------------------------------- > PhotoMail - it's free and works with Yahoo! 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