Ken, LF folks
I would have said 370C (700F) for LF hand solder tip temps on chips, and
higher for connectors and other heavy components, I think it works
better, and if you increase the temp, your dwell time can be reduced,
thereby limiting the time the component leads and component body see
temp.
I agree with your preheat temps.
asta
Rick Smith
Senior Materials & Process Engineer
Phone: (512)652-3544
Fax: (512)652-3545
Cell: (512)299-6925
Email: [log in to unmask]
ClearCube Technology, Inc
8834 Capital of Texas Hwy N
Austin, TX 78759
www.clearcube.com
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Lee Whiteman
Sent: Thursday, December 01, 2005 6:12 PM
To: [log in to unmask]
Subject: Re: [LF] Lead-free Hand Soldering Implementation
Ken,
Here are a few things that we found when performing Lead Free Hand
Soldering:
1. Because of the higher soldering temperatures, the solder tip
temperature
has to be set higher. For example, with the solder alloys soldered, ACI
found that the solder tip temperature had to be set at 343oC for Lead
Free
solders, as opposed for 315oC for SnPb.
2. Selecting the solder tip becomes more important for Lead Free
soldering.
Too small a solder tip will not provide sufficient heat transfer during
the
soldering process.
3. It was discovered that a longer dwell time - the time the soldering
iron
was in contact with the hardware - was required to promote adequate heat
transfer during the soldering process.
4. The higher soldering temperature requires that the soldering iron
must
remain clean and coated with the solder alloy. The higher soldering
temperatures can result in the soldering iron tip becoming oxidized if
not
cleaned and coated. Lead Free solders are more sensitive to the effects
of a
dirty soldering iron.
5. Solder tips used to solder with Lead Free solders must be separated
from
solder tips used with SnPb solders. Using a SnPb coated solder tip to
solder
with Lead Free solders can result in a solder joint contaminated with
Lead
(Pb). There is some evidence that Lead Free solders joints, contaminated
with Pb, are not as reliable as uncontaminated Lead Free solder joints.
6. Lead Free solders do not wet as well as SnPb solders. To improve
wetting,
a more active solder flux may be considered. However, if a more active
flux
is used, more aggressive cleaning processes will be required. Active
fluxes
leave residues on hardware, which will promote dendritic growth and poor
conformal coat adhesion.
7. Due to the higher soldering temperatures, the soldering iron had to
be
removed faster for Lead Free than for SnPb. Lead Free solders and SnPb
solders have different cooling rates and cooling characteristics. Quick
solder iron removal prevents the soldering process from disturbing the
solder joint and the board pads. Lifted pads and lifted fillets are more
prominent with Lead Free Solders.
8. Recommend preheating the PWA between 100C to 120C. These
temperatures
will be dependent upon the board material, board thickness, and
configuration. Preheating the boards before soldering offers several
advantages:
- Prevent board and component thermal shock
- Reduces the amount of thermal gradients in the board
- Prevent pad lifting by reducing the solder tip contact time
- Reduces soldering dwell time
- Improve wetting during the soldering process by having the board at an
elevated temperature during the soldering process
- Reduces the effect of Coefficient of Thermal Expansion (CTE) mismatch
between components and boards
9. Use a hot plate during hand soldering. We recently did a Lead Free
audit
at a customer's place and found the operator had a difficult time
performing
hand soldering with Lead Free solders (SAC-305). A hot plate was
provided to
the operator - the operator was able to perform hand soldering much
easier
than before.
If you have any questions, give me a call off-line.
Hope this helps.
Good Luck.
Lee Whiteman
Senior Manufacturing Engineer
American Competitiveness Institute
E-Mail: [log in to unmask]
Ph: (610) 362-1200 x208
Fax: (610) 362-1290
This message is for informational purposes only and does not supersede,
modify, or create any agreements with ACI. Information contained in this
message does not bind ACI or its affiliates to any commitment, either
express or implied, unless ratified in writing by an authorized
representative.
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Kanaiyalal Patel
Sent: Wednesday, November 30, 2005 1:10 PM
To: [log in to unmask]
Subject: [LF] Lead-free Hand Soldering Implementation
Lead-free Implementers,
I have been assigned to implement Lead-free Hand Soldering on our
manufacturing floor. I believe many of us have already implemented
similar
activities on their floor. I really appreciate if someone can share
their
experience to make it foolproof and also provide signs/warning/alert
documents prepared for the area to warn everyone including operators.
Any help will be highly appreciated.
Re,
Ken Patel
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To unsubscribe, send a message to [log in to unmask] with following text
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the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop/(start) delivery of Leadree for vacation breaks
send: SET Leadfree NOMAIL/(MAIL)
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
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-------------------------------------------------------------------------------Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL)
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
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