Lutefisk, dried cod cured in lye. On Thu, Dec 12, 2013 at 2:29 PM, Stadem, Richard D. < [log in to unmask]> wrote: > What fish? > > -----Original Message----- > From: Whittaker, Dewey (EHCOE) [mailto:[log in to unmask]] > Sent: Wednesday, December 11, 2013 9:29 AM > To: TechNet E-Mail Forum; Stadem, Richard D. > Subject: RE: [TN] Moisture Level Determination of PCB > > I (out of this world class; The PB, Class 3, 3/A Aerospace) do not allow > any Lead-free Tin finishes and will never allow ImSn. Fresh raspberry > croissants at the local Starbucks have a longer shelf life than ImSn. IMHO, > if you must use them, keep them in the approved packaging (bags, etc.)with > the HIC still showing acceptable and a CoC that they were dry (at or below > the allowable percentage level of moisture) and solderable at time of > delivery and stored in a controlled (monitored) atmosphere, until time of > use. When they are pulled for use (out of package), they should be held in > a nitrogen environment until paste and reflow and or after paste and place > if reflow is not immediate. A general rule is a 72 hour window prior to > final reflow assembly. Any other handling/baking is like playing > Wisconsin/Minnesota roulette (all the chambers are full, they don't want > any loose lead rounds falling into the ice holes and endangering the fish). > Dewey > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. > Sent: Wednesday, December 11, 2013 7:50 AM > To: [log in to unmask] > Subject: Re: [TN] Moisture Level Determination of PCB > > But you do not need to bake tin-finished CCAs, IPC-1601 also includes > information on how to desiccate them at room temperature. While it may take > a week or two, you can still ensure the board is sufficiently dry such that > it can withstand normal leaded and lead-free mass reflow and wave solder > processes without loss of solderability, delamination, CAF formation, and > other moisture-related issues. That is the point I am trying to get across. > And I consider both you and Grunde to be top-tier engineers. > > -----Original Message----- > From: Steve Gregory [mailto:[log in to unmask]] > Sent: Wednesday, December 11, 2013 8:00 AM > To: [log in to unmask]; Stadem, Richard D. > Subject: RE: [TN] Moisture Level Determination of PCB > > Hi Richard, > > I guess I'm not top-tier because I've never had any luck with tin finished > boards. It's turned into a huge disaster every time I've baked them. So I > just don't anymore... > > Steve > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. > Sent: Wednesday, December 11, 2013 6:32 AM > To: [log in to unmask] > Subject: Re: [TN] Moisture Level Determination of PCB > > If the guidelines within IPC-1601 are followed, there should be no grief, > not even for PWB finishes other than ENIG and HASL. > A top-tier process engineer understands how to set up the optimum baking > time and temperature schedule for any given PWB size and type, such that > you can remove at least 80% of the saturated moisture content by weight > with no compromise to the PWB solderability, for any PWB, for any finish. > > Just because the boards are stored in sealed bags means very little. > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Grunde Gjertsen > Sent: Tuesday, December 10, 2013 5:23 PM > To: [log in to unmask] > Subject: Re: [TN] Moisture Level Determination of PCB > > Hi > > Without being too scientific about it. > > 1. For FR4 it is generally not that critical if storage and shop floor > conditions is reasonably controlled and the boards are stored in sealed > bags. J-STD-033 is not really relevant but if you can handle the logistics > comfortably it seems like a good idea to me. > Be very careful about baking out anything other than HASL and ENIG, all > sorts of grief can follow. > If what worries you are delamination and leadfree soldering the key is to > choose a laminate that is suitable for the design, process and to some > extent end user application. (Class 3) Anything polyimide/flex take much > more care and bake out prior to soldering and for each thermal event > according to manufacturers recommendations unless you can store the boards > in a dry cabinet between. Do not trust the boards to be dry enough from the > manufacturer. > > 2. Yes. > > Best regards > Grunde > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of MaryJane Chism > Sent: 10.desember 2013 18:32 > To: [log in to unmask] > Subject: [TN] Moisture Level Determination of PCB > > Hi Group, > > I have a question concerning the moisture level of a printed circuit board. > > 1) Does a printed circuit board have an MSL level? We have been treating > the printed circuit as an MSL Level 3. > 2) Should we consider the wave solder as a thermal event even though the > wave carriers shield all areas of the printed circuit board except the > specific through hole areas. We currently do but should we? > > Any information you give will be helpful, > > Thanks, > > Mary Jane > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. 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