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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