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Subject:
From:
Dwight Mattix <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dwight Mattix <[log in to unmask]>
Date:
Thu, 29 Mar 2012 10:45:12 -0700
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That performance deserves 
<http://www.itst-shirttime.com/shop/1455-i-got-to-second-base-with-a-tsa-agent-funny-graphic-t-shirt.htm>a 
t-shirt.

09:44 AM 3/29/2012, Graham Collins wrote:
>I figure Doug should pack a bunch of cans in his checked luggage, maybe
>toss a couple of sample circuit boards on top of that, and chuck it
>through the x-ray machine.  What could possibly go wrong?
>
>Actually, since it has been brought up he will probably try to sneak
>that stuff into Hillman's luggage.
>
>A friend took a couple of boxes of chalk on a trip to a less privileged
>country, with the intent to give them to a school.  Apparently boxes of
>chalk when x-rayed straight on cause a bit of excitement at the x-ray
>machine...
>
>Nothing like a good strip search to start a trip.
>
>regards,
>  - Graham
>
>-----Original Message-----
>From: Gregg Owens [mailto:[log in to unmask]]
>Sent: Thursday, March 29, 2012 2:52 AM
>To: TechNet E-Mail Forum; Collins, Graham (FN) @ PRG - ESI
>Subject: RE: NTC RE: [TN] Rework Concern and Question / Mtn Dew
>
>Graham:
>
>Do you actually expect Americans to take large quantities of clear
>liquids on airplanes? I am sure our security people would tear such suit
>case apart after they looked at the x-ray of such a bag. Our security
>folks really don't have a well-developed sense of humor.
>
>Gregg Owens
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins
>Sent: Wednesday, March 28, 2012 6:12 AM
>To: [log in to unmask]
>Subject: [TN] NTC RE: [TN] Rework Concern and Question / Mtn Dew
>
>You don't bring your own supply???  Or is it considered a illegal
>substance in the UK, similar to trying to bring KinderEggs into the USA?
>
>regards,
>  - Graham
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
>Sent: Wednesday, March 28, 2012 10:09 AM
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>Ohhhhh, I can tell you from experience there is no Mt Dew or Diet Mt.
>Dew in the UK.  I go into withdrawal every time I go there.  Last time I
>came back through the Detroit Airport, the lady in the convenience shop
>said she had never seen someone so happy to find a bottle of Diet Mt.
>Dew. "Did
>you just get back from the UK?"   Hilarious.
>
>Doug Pauls
>
>
>
>From:   Joyce Koo <[log in to unmask]>
>To:     <[log in to unmask]>
>Date:   03/28/2012 07:57 AM
>Subject:        Re: [TN] Rework Concern and Question
>Sent by:        TechNet <[log in to unmask]>
>
>
>
>Depend upon which country, cross the boarder you don't have that much
>real "stuff" in it.  (not sure about UK.  It might be the same, since we
>both got Queen on our coins).
>
>Joyce Koo
>Materials Researcher - Materials Interconnect Lab Research In Motion
>Limited
>Office: (519) 888-7465 79945
>Mobile: (226) 220-4760
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
>Sent: Wednesday, March 28, 2012 8:53 AM
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>Mountain Dew also works for some people I know (one in particular)
>
>Regards,
>George
>George M. Wenger
>Senior Principal Reliability / FMA Engineer Andrew Corporation -
>Wireless Network Solutions
>40 Technology Drive, Warren, NJ 07059
>(908) 546-4531 Office (732) 309-8964 Mobile
>E-mail: [log in to unmask]
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Stewart McCracken
>Sent: Wednesday, March 28, 2012 8:42 AM
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>Oops, just noticed a couple of good typo's in my previous post!
>Should be keV and not kV throughout and Sn La1 peak is at 3.44keV not
>1.74kV!
>Other than that - perfect, the lesson here - more coffee before morning
>e-mails....
>
>(and its probably still an escape peak rather than a real Si peak!)
>
>Stewart
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Stewart McCracken
>Sent: 28 March 2012 09:43
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>Hi Folks,
>
>Following some of the previous posts, I believe that the "Si" peak which
>is being "detected" during EDX, is not a Si peak at all!
>There is a very good chance that what the system is showing is an
>artefact of the EDX system know as an "escape peak". In this case, a
>small "false"
>peak occurs at 1.74kV below strongest peak (which in this case will be
>Sn
>La1 at 1.74kV), giving you what appears as a peak at around 1.7kV which
>is around the same as the Si Ka peak 1.74kV).
>Bottom line is that the "Si" peak which is being described is most
>likely an EDX artefact and not a Si peak at all!
>
>Kind regards,
>
>Stewart
>
>
>Stewart McCracken
>MCS Ltd.
>Centre House
>Midlothian Innovation Centre
>Roslin
>Midlothian
>EH25 9RE
>U.K.
>
>t. +44 (0)131 440 9090
>m. +44(0)7711 541735
>e. [log in to unmask]
>w. www.themcsgroup.co.uk
>
>
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Fenner
>Sent: 28 March 2012 00:30
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>I sincerely doubt any Si in the solder, Probably the Si you are seeing
>is from silica filler in the device body or something like that.
>So what is happening to stop solder re-melting?
>Possibly if the device leads are copper then with extended heating the
>Cu can dissolve into the near pure Sn solder and drive the liquidus up -
>and the longer you heat the greater the Cu dissolution and the higher
>the MP.
>You are probably dissolving out the PCB pad/through hole barrel as well.
>The Cu/Sn phase diagram looks like a tick or check mark. The short Sn
>down stroke side is from 232 to low point of 227 and the Cu up stroke
>side is near vertical to MP of Cu somewhere over 1000C, so you get a
>very rapid temp increase for small compositional change.
>
>Suggest try come in with a hot iron (more than 700) to melt out the
>existing composition quickly or flush with more solder to add tin to the
>mix and depress MP.  Or both.
>
>
>Regards
>
>Mike Fenner
>Bonding Services & Products
>T: +44 [0] 1865 522 663 E: [log in to unmask]
>
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
>Sent: Tuesday, March 27, 2012 10:01 PM
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>I think, but am not sure, that you are attempting to remove a new
>component whose leads are FINISHED (not soldered) with SAC305 solder,
>and that is why you measure Sn98 on the parts straight out of the tape
>(I am going to disregard the SEM analysis of 2% silicon for a moment).
>
>Secondly, the new parts were probably soldered to the PWB with SAC305
>solder as well, and that is why when you attempt to unsolder them or
>bring them into liquidus, you are having more difficulty than you did
>with the old parts.
>
>Not only were the old parts finished with Sn63 solder, but they were
>also soldered in place with Sn63 solder.
>The new parts are meant to be RoHS compliant, and apparently they are,
>with a Sn level of 98%, and no Pb in sight on the SEM diagram. If that
>were the only change, you should notice no difference in the ability to
>remove the part if they were, in fact, soldered to the PWB with Sn63;
>the plating change alone would not make any noticeable difference.
>
>Soldering them to the PWB with lead-free SAC305 alloy would make a huge
>difference in your ability to unsolder and remove the part, no matter
>what finish was used to plate the part.
>
>Silicon will not break down and become part of an alloy under 1000 deg.
>C.
>The 2% SEM pickup is probably silicon chips or dust from the component
>body.
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
>Sent: Tuesday, March 27, 2012 3:25 PM
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>Dave Hillman,
>
>With your metallurgical background you might be a better person than I
>to make a comment.  I'm not sure I've even had or seen an occasion where
>something dissolved in the bulk solder and increased the
>melting/solidification temperature.  Yes I've seen the leading edge of
>solder as it flows and wets a surface dissolve metallization and freeze
>because the local meting temperature changed but I've never seen that
>happen to the bulk of a solder joint
>
>Regards,
>George
>George M. Wenger
>Senior Principal Reliability / FMA Engineer Andrew Corporation -
>Wireless Network Solutions
>40 Technology Drive, Warren, NJ 07059
>(908) 546-4531 Office (732) 309-8964 Mobile
>E-mail: [log in to unmask]
>
>
>-----Original Message-----
>From: Leland Woodall [mailto:[log in to unmask]]
>Sent: Tuesday, March 27, 2012 4:14 PM
>To: TechNet E-Mail Forum; Wenger, George M.
>Subject: RE: [TN] Rework Concern and Question
>
>George,
>
>It's been a long day, and maybe I'm not making myself too clear.
>
>We're not being able to achieve a liquidus state with a 700 degree F
>soldering iron.  We're not trying to melt the lead, just the solder
>that's holding it to the PCB.  We're not accomplishing that with the new
>component, so I'm thinking something has mixed with the solder joint and
>
>has raised the resultant reflow temperature.
>
>Leland
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
>Sent: Tuesday, March 27, 2012 4:10 PM
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>Leland,
>
>Am I missing something?  I don't think it really matter that the lead
>base material or lead surface finish is.  What matters is the solder
>used to attach the lead to the board.  When you desolder a lead you
>don't melt the lead you melt the solder.
>
>Regards,
>George
>George M. Wenger
>Senior Principal Reliability / FMA Engineer Andrew Corporation -
>Wireless Network Solutions
>40 Technology Drive, Warren, NJ 07059
>(908) 546-4531 Office (732) 309-8964 Mobile
>E-mail: [log in to unmask]
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
>Sent: Tuesday, March 27, 2012 4:05 PM
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>Hi Leland - I recommend you find out the lead base metal composition. If
>
>you shot an SEM-EDS of the lead toe, you could be getting the Si from
>the base metal composition and not part of the solder alloy composition.
>
>Dave Hillman
>Rockwell Collins
>[log in to unmask]
>
>
>
>Leland Woodall <[log in to unmask]> Sent by: TechNet
><[log in to unmask]>
>03/27/2012 02:52 PM
>Please respond to
>TechNet E-Mail Forum <[log in to unmask]>; Please respond to Leland Woodall
>
><[log in to unmask]>
>
>
>To
><[log in to unmask]>
>cc
>
>Subject
>Re: [TN] Rework Concern and Question
>
>
>
>
>
>
>Vladimir,
>
>We analyzed raw components straight out of the tape and reel packaging.
>The site selection was on the bottom side of the leads at the toe.
>
>Leland
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of vladimir Igoshev
>Sent: Tuesday, March 27, 2012 3:12 PM
>To: [log in to unmask]
>Subject: Re: [TN] Rework Concern and Question
>
>Sorry Ben, it doesn't.
>Leland,
>
>What you are saying sounds strange. What does it mean: "We've analyzed
>the lead material beneath the SEM and it returns 98% tin and 2%
>silicone"?
>Did
>you analyzed leads or solder? Where the analysis was taken from? Did you
>
>analyzed leads with pads ripped off?
>
>Regards,
>
>Vladimir
>
>SENTEC Testing Laboratory Inc.
>11 Canadian Road, Unit 7.
>Scarborough, ON M1R 5G1
>Tel: (416) 899-1882
>Fax: (905) 882-8812
>www.sentec.ca
>
>-----Original Message-----
>From: "Gumpert, Ben" <[log in to unmask]>
>Sender: TechNet <[log in to unmask]>
>Date: Tue, 27 Mar 2012 18:58:21
>To: <[log in to unmask]>
>Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
>         "Gumpert, Ben"
>         <[log in to unmask]>
>Subject: Re: [TN] Rework Concern and Question
>
>Leland,
>
>I won't claim to be an expert, but this website seems to imply something
>
>along those lines.
>http://resource.npl.co.uk/mtdata/phdiagrams/sisn.htm
>
>Ben
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall
>Sent: Tuesday, March 27, 2012 2:18 PM
>To: [log in to unmask]
>Subject: EXTERNAL: [TN] Rework Concern and Question
>
>Folks,
>
>We've ran across a strange incident and I'd like a little advice from
>the group.
>
>We recently underwent a component vendor change, and part of the first
>group of boards were misbuilt due to incorrect polarity (the part
>marking was misinterpreted by the vision operator).
>
>Anyway, an attempt to remove the part by our Repair group resulted in
>lifted pads on 10 of the first 12 boards.  We've analyzed the lead
>material beneath the SEM and it returns 98% tin and 2% silicone.  The
>old style component comes off quite easily (within 3 seconds), and an
>analysis of its leads shows to be 100% tin.  It's a 6 pin diode with
>very little mass.
>
>What's going on here?  Does a 2% silicone mix raise the melting point of
>
>solder by 200 degrees C?
>
>Please help me understand.
>
>Thanks,
>
>Leland
>
>________________________________
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