Hi
I don't believe there is a recommended profile for hand soldering. I imagine
this is principally because it would be near impossible/impractical to set
up monitoring and process controls for it. Imagine probing or measuring and
recording joint temperature individually on a routine basis at every
soldering station. For various reasons (see below) I'm not sure how useful
it would be anyway.
Most soldering irons are temperature controlled to set an optimum tip
temperature, and it is possible to measure the excursions from that,
although it is not routinely done as a production control. The usual
temperature concern in hand soldering is overheating of device/component
followed by damage to PCB (measling, pad lift).
So process control is done by controlling tip temperature control and time.
If components are heat sensitive they can be protected by specially designed
tweezers applied to lead or similar procedures.
The tip temperature sets the max temperature possible and the time limit
sets the max temperature achieved in the soldered area and also the amount
of heat inputted.
To give you a rough idea of what could be going on. Assume a tip temperature
drop of say 20C on rapid soldering, a further drop of say 40C from tip to
work. So a notional 300C tip temperature could produce a temp on the work of
around 260 on the first joint and say 240C worst case on the last. The
actual temperature achieved by the work would depend on the rise
rate(determined by thermal inertia/mass of the joint and how long the tip is
in contact. Typically this is around 1.0 to 1.25 seconds. The time is
actually operator determined, as the tip is removed as soon as good joint
shape is achieved and will therefore vary, first joints might well be
shorter times than subsequent ones. So even if you had a profile it would
have to be specified with quite wide temperature and time bands.
These intrinsic variations were one of the original drivers to machine
soldering for mass production of solder joints.
I think it might be more useful to "probe" the customer rather than the
joint to identify the root  cause of his concern. Why is he asking? Then you
can address that. 


Regards


Mike Fenner

Bonding Services & Products
M: +44 [0] 7810 526 317
T: +44 [0] 1865 522 663
E: [log in to unmask]

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard D. Krug
Sent: Friday, September 21, 2012 1:35 PM
To: [log in to unmask]
Subject: [TN] IPC Standard Temperature Profile for RoHS Pb Free Solder (Hand
Soldering)?

A customer has asked whether IPC has a standard temperature profile for RoHS
Pb-Free hand soldering.  I'm not aware of one and since there are multiple
RoHS compliant alloys I don't know whether there should or could be one.  

Is there any such document or series of documents?  

Dick Krug, CSSBB, CSMTPE
Senior Process Engineer
Sparton Complex Systems
30167 Power Line Road
Brooksville, FL  34602-8299
p (352) 540-4012  (Internal Ext. 2012)
[log in to unmask]

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