Try using leadfree solder on Nuclear Power  Plant..?




At 23:54 2011/5/12, Mike Fenner wrote:
>There are known compatibility issues with some alloys and joint
>configurations and in your case you would have determine the unknown ones.
>My question to you would be: Why go there?
>1) ROHS allows the use of leaded solders for repair of pre ROHS products.
>2) Infrastructure [power stations ] is presently excluded from ROHS along
>with anything else where high reliability is required  (Aviation, medical,
>automotive etc).
>3) Suggest that even assuming Pb free solders were environmentally superior
>(and some doubt this), in your application the environmental impact of using
>Pb-free solders would be negligible and far outweighed by the possible
>consequences of unreliable joints.
>Regards
>
>
>Mike
>ü Please consider the environment before printing this e-mail
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Goodyear, Patrick
>Sent: Sunday, May 01, 2011 7:12 AM
>To: [log in to unmask]
>Subject: [TN] Repair / Rework on non-in-house RoHS compliant boards
>
>As a technician that does frequent board level repair rework some
>questions have come to mind.   While the majority of my work is legacy
>i.e. vintage (1968) we will face these concerns in the near future.  The
>boards I primarly work on are Nuclear graded Class IE, (high
>reliability, seismically qualified, etc.) high dollar boards, typically
>in the 3-10g range and are not throw-aways, most have components that
>are no longer manufactured.
>I am looking to the industry to find best practices, this is one of the
>places that was suggested for posting.   Any help you can give me would
>be appreciated.
>
>With pre RoHS solders most if not all of major manufacturers used 63/37
>solders and repair rework was easy, one just used 63/37.
>
>With the adoption of RoHS controls and the subsequent use of many
>different alloys of lead free solders, (at least 6 I know of), the
>following comes to mind:
>1. Are there compatibility issues mixing between the various alloys of
>lead-free employed currently in electronics manufactures?   In strength
>and reliability primarly.
>2. How does the technician determine the correct alloy of lead-free
>solder to use?
>
>3. How does the technician determine what alloy was originally used by
>the manufacturer?
>
>4. Will IPC 7711A / 7721A standards be updated to delineate alloy
>determination and / or an alternate methods for the complete removal of
>lead-free solders and subsequent repair using 63/37 or lead-free alloys?
>Pat Goodyear
>Control Technician
>Pacific Gas and Electric Company
>Diablo Canyon Nuclear Power Plant
>PO Box 56
>Avila Beach, CA. 93424
>805-545-4312
>
>
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