The Silver Saver paper is simply a paper with a very low sulpher content. Standard paper liners will cause the IAg finish to tarnish, more quickly than if no liner is used at all. But as Franklin pointed out, no paper leads to abrasion issues. The finish is typically only 15-17 uinches (not microns) thick, and can be abraded through, exposing the underlying copper to oxidize. So, a good practice is to specify the silver saver paper between each board, and hermetically seal the brick with a special low-outgassing shrinkwrap with dessicant included. If the IAg finish is inadvertently exposed and does tarnish slightly, it usually does not affect the solderability, unless the silver oxides are such that the copper is exposed. Then troubles begin. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard Sent: Thursday, June 01, 2006 10:20 AM To: [log in to unmask] Subject: Re: [TN] Packaging requirements for IAg Finished PWBs This is very timely. We have just been realizing that we have no formal handling procedures in place for the newer finishes, either. We have used the robust HASL finish for so long, I don't think people realize how different these PCB's can be. Can you tell me if you have any guidelines for Immersion white Sn finish, as well? Or is the information below applicable to that as well? We had a board supplier tell us that ImmSn needs silver saver paper as well. The idea of getting them packaged in small quant's from the manufacturer is a great idea, as well. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell Sent: June 1, 2006 9:00 AM To: [log in to unmask] Subject: Re: [TN] Packaging requirements for IAg Finished PWBs Yes, we use a neutral pH paper, almost like tissue paper and fold 10 bds max into bundles, then package these in neutral pH plastic bags. Scratches are not so much this issue, it's more of abrasion prevention as well as protection from the environment. We have customer's however that once the product is received they completely remove the product from the packaging and place them open in bins until use. As a practice we pass along assembly and handling guidelines to all customers who request silver finish for the first time, and with new customers order silver finish product. Silver finish reacts to atmosphere more dramatic than tin-lead, the tin-lead finish is also more durable and less affected by handling, contaminates, etc so more controlled measures must be taken with silver finish. Also, it is best to perform the silver finish process as close to the end of the fabrication process as possible. We typically perform this process after rout and final inspection. Silver finish is applied, tape testing and visual inspection is performed and the product is immediately packaged. The following is an excerpt from such a procedure. ============== 5.0 Handling, packaging, and storage 5.1 It is recommended that gloves be used for all handling after the immersion silver process. 5.2 Salts and acids from fingerprints may tarnish the silver finish. 5.3 Surfactants and/or acid cleaners should not be used on silver finish boards. Clean only with DI water rinses. 5.4 Silver plated boards should be packaged as soon as possible to avoid exposure to sulfides and chlorides in the air. 5.5 Bundle wrap silver parts in clean acid/sulfur free paper. Neutral pH paper is sufficient. 5.6 Storage should be in sealed neutral pH plastic bags to eliminate direct contact with the air. 5.7 Do not allow sulfur bearing plastic to contact the silver finish. 5.8 Do not use desiccant in the packages with silver plated boards. 5.9 Do not use rubber bands on boards. Most rubber bands contain Sulfur compounds. ============== Franklin -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Gary Camac Sent: Thursday, June 01, 2006 9:47 AM To: [log in to unmask] Subject: [TN] Packaging requirements for IAg Finished PWBs Good morning all, I am struggling through a rewrite of our material specification for PWBs. I have seen the recommendation that cover sheets and interleaf sheets should be used to prevent scratches on IAg finished PWBs. Have those that are using IAg seen this as necessary? We eliminated this requirement on Sn/Pb finished PWBs some time ago without any negative effects. Thanks, Gary Camac --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------