I vote for Chris' minor change. This best covers most of the scenarios we will see. Randy Reed Merix Corporation -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Conklin, C J Sent: Wednesday, April 20, 2005 4:02 AM To: [log in to unmask] Subject: Re: [IPC-600-6012] Proposed IPC-6012B Change for SnPb in SMOBC I would agree with the wording as proposed by Clarence Knapp with one minor change just for consistency: "Solder may extends 0.010" on the circuitry underneath the solder mask at the interfaces of the soldered areas and non-soldered areas. Final finish used to preserve solderability under SMOBC on areas not to be soldered is permitted on 1% of the conductor surfaces for Class 3 and 5% of the conductor surfaces for Class 1 and 2." Interestingly, I just had this same conversation with Mark Buechner on Friday. We build very few solder plated and selectively striped PWBs. However, we do produce a significant number of conventional SMOBC PWBs with HASL. From time to time, we end up with small areas where the circuit has solder mask over solder. Criteria that would allow this to be accepted on a limited basis would have our approval. Therefore, we would vote yes for criteria that covered both the encroachment under the mask at the interface for selectively stripped parts and solder, or whatever final finish is being used, under solder mask on interior circuits as described by Mike Hill. Best regards, Chris Conklin PWB Quality Engineering Lockheed Martin Systems Integration - Owego 1801 State Route 17C MD0409 Owego, NY 13827 Phone: 607-751-4251 FAX: 607-751-7714 e-mail: [log in to unmask] <mailto:[log in to unmask]> -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]]On Behalf Of Michael E. Hill Sent: Tuesday, April 19, 2005 5:49 PM To: [log in to unmask] Subject: Re: [IPC-600-6012] Proposed IPC-6012B Change for SnPb in SMOBC Clarence, That's looks very good. Nice job. It's got my vote. Mike Hill -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]]On Behalf Of Knapp, Clarence W. Sent: Tuesday, April 19, 2005 4:21 PM To: [log in to unmask] Subject: Re: [IPC-600-6012] Proposed IPC-6012B Change for SnPb in SMOBC I like the distance measurement of 0.010" at the interface of solder mask to circuit. But Mike has a good point. May be the criteria should be something like "Solder may extends 0.010" on the circuitry underneath the solder mask at the interfaces of the soldered areas and non-soldered areas. Plating used to preserve solderability under SMOBC on areas not to be soldered is permitted on 1% of the conductor surfaces for Class 3 and 5% of the conductor surfaces for Class 1 and 2." Clarence W Knapp M&P Engineering Ph 818 715 2478 Fx 818 719 7769 [log in to unmask] -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Michael E. Hill Sent: Tuesday, April 19, 2005 10:40 AM To: [log in to unmask] Subject: Re: [IPC-600-6012] Proposed IPC-6012B Change for SnPb in SMOBC There is a problem just using distance. If a small piece of solder left on an interior curcuit, we would be scrapping a good board. Also, since the exposed copper statement has always been in these percentages, it makes both paragraphs the "same criteria" (i.e. easier to understand and remember). Mike Hill -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]]On Behalf Of w.glenn.colescott Sent: Tuesday, April 19, 2005 1:18 PM To: [log in to unmask] Subject: Re: [IPC-600-6012] Proposed IPC-6012B Change for SnPb in SMOBC John, I like the idea of defining the distance under the mask better than listing a percentage. I agree it is easier to understand, measure, and enforce. Other than that, I would support the change. Thanks, W. Glenn Colescott Component Line Leader - PCBs & Substrates Component Engineering Liaison Manager - North America Delphi Electronics & Safety Division One Corporate Center - Mail Station R117 P.O. Box 9005 Kokomo, IN 46904-9005 Phone; (765)-451-1258 FAX; (765)-451-9647 Email; [log in to unmask] -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]]On Behalf Of Nick Koop Sent: Tuesday, April 19, 2005 11:35 AM To: [log in to unmask] Subject: Re: [IPC-600-6012] Proposed IPC-6012B Change for SnPb in SMOBC John, For some perspective, paragraph 3.3.2.12 in IPC 6013 "Solder Wicking/Penetration" (see pg 9) was intended to cover issues of flexible coverlay and solder that extends underneath the coverlay on occasion. We did not distinguish between coverfilm, soldermask, PIC or the like. The limits are more generous and easier to measure than percentages. Class 3 allows 0.3 mm (0.012"), Class 2 allows 0.5 mm (0.020"), Class 3 allows as agreed between user and supplier. This may be something the 6012 team may want to consider. Regards, Nick Koop Minco Products, Inc >>> [log in to unmask] 04/19/05 11:05AM >>> Colleagues, The IPC D-33a Rigid Board Performance Task Group is beginning the development of an Amendment 1 to IPC-6012 Revision B. Relative to this is a request to modify and append text in section 3.5.4.7, Final Finish Coverage (Areas not to be soldered). Background on change request: A printed board was found to have small amounts of Tin Lead under the solder mask with reflow/SMOBC finish. The part has been fabricated using the selective solder strip process. The customer rejected the parts for small amounts of tin lead found on bare copper and under the solder mask, claiming with Tin Lead, the part no longer was Solder Mask over Bare Copper. There is currently no IPC specification that prohibits such Tin Lead on the bare copper. However, at some point it becomes a workmanship issue per IPC 6012B paragraph 3.3.9. Rationale for change request: This new accept/reject criteria provides a check and balance for the tin lead strip process (i.e., the process is not capable of absolute ZERO tin lead as there is always trace amounts on some circuits) and at the same time we don't want to be throwing away printed boards that are functionally fine. Proposed Change within 3.5.4.7 of IPC-6012B: 3.5.4.7 Final Finish Coverage Final finish shall meet the solderability requirements of J-STD-003. 3.5.4.7.1 Exposed Copper (Areas not to be soldered) Exposed copper on areas not to be soldered is permitted on 1% of the conductor surfaces for Class 3 and 5% of the conductor surfaces for Class 1 and Class 2. Coverage does not apply to vertical conductor edges. 3.5.4.7.2 Tin-Lead under SMOBC Tin or Tin Lead under SMOBC on areas not to be soldered is permitted on 1% of the conductor surfaces for Class 3 and 5% of the conductor surfaces for Class 1 and 2. If you approve the proposed change without comment, please send your approval, by May 3rd, to [log in to unmask] If there is a need to comment on and discuss this within the task group, please respond through this e-mail forum. Thanks, John Perry Technical Project Manager IPC 3000 Lakeside Drive # 309S Bannockburn, IL 60015 [log in to unmask] 1-847-597-2818 (Phone) 1-847-615-7105 (Fax) 1-847-615-7100 (Main) ************************************************************************ **** ************ Note: The information contained in this message may be privileged and confidential and thus protected from disclosure. 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