Dave,
If the surface was heavily oxidized then how the component was originally soldered???
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: "David D. Hillman" <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
Date: Tue, 27 Mar 2012 17:24:01
To: <[log in to unmask]>
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
<[log in to unmask]>
Subject: Re: [TN] Rework Concern and Question
Hi George - yes, what ever is the lowest temperature melting element in
the "mix", it will typically sets the stage for what will be the initial
melting point depending on how the different elements can combine/alloy.
What Leland has been describing almost sounds like "foot in mud" where he
is not getting a metallurgical reaction at the component foot interface.
If it was organic driven, we would expect some type of burning or
charring. Richard may have hit the right clue - what if the component lead
is a lead-free, high tin content surface finish and was heavily oxidized?
That would give a poor melting response. I think the Si SEM reading is
just a confusing factor that my not be related to the issue.
Dave
"Wenger, George M." <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
03/27/2012 03:25 PM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
"Wenger, George M." <[log in to unmask]>
To
<[log in to unmask]>
cc
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
________________________________
?Confidentiality Notice:
This transmission (including any attachments) may contain confidential
information belonging to the sender and is intended only for the use of
the party or entity to which it is addressed. If you are not the intended
recipient, you are hereby notified that any disclosure, copying,
distribution, retention or the taking of action in reliance on the
contents of this transmission is strictly prohibited. If you have received
this transmission in error, please immediately notify the sender and erase
all information and attachments.?
______________________________________________________________________
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]
______________________________________________________________________
________________________________
?Confidentiality Notice:
This transmission (including any attachments) may contain confidential
information belonging to the sender and is intended only for the use of
the party or entity to which it is addressed. If you are not the intended
recipient, you are hereby notified that any disclosure, copying,
distribution, retention or the taking of action in reliance on the
contents of this transmission is strictly prohibited. If you have received
this transmission in error, please immediately notify the sender and erase
all information and attachments.?
______________________________________________________________________
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]
______________________________________________________________________
________________________________
?Confidentiality Notice:
This transmission (including any attachments) may contain confidential
information belonging to the sender and is intended only for the use of
the party or entity to which it is addressed. If you are not the intended
recipient, you are hereby notified that any disclosure, copying,
distribution, retention or the taking of action in reliance on the
contents of this transmission is strictly prohibited. If you have received
this transmission in error, please immediately notify the sender and erase
all information and attachments.?
______________________________________________________________________
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]
______________________________________________________________________
|
