To elaborate a little on the answer below, the appropriate tip temperature for a
particular application varies considerably depending on both the technology used
and the characteristics of the individual models.
There are two technologies in use right now - stored heat and direct power. A
direct power iron can, as a general rule, solder the same joint roughly 100
degrees lower than a stored heat iron. This is because the relevant factor is
not really the temperature of the tip, but is the amount of heat energy the tip
can deliver to the joint.
A stored heat iron uses a large heater to store heat in a high mass tip. When
you apply that tip to the joint the stored heat is dumped into the joint and the
heater begins restoring the energy to the tip. (Different models do this more or
less efficiently.) In order to deliver enough heat energy to the joint to do the
job the temperature of the tip has to be set fairly high above the melting point
of solder. (Of course, the mass of the joint has a lot to do with it too, but
we're assuming comparable loads and tip shapes.)
A direct power iron uses a very low mass tip and a small mass heater inserted
directly into the tip. This means that there is very little stored heat in the
tip - the heat delivery comes from the heater, not the tip. In this case the tip
is acting not as a storage medium for the heat energy, but as an interface
between the heater and the joint. Because of this the mass of the joint, rather
than the mass of the tip, determines how much heat is delivered to it. Putting
all these dynmamics together gives us an iron that will solder the same joints
at lower temperatures and with higher throughput (consitency of heat delivery
from joint to joint.)
For more detailed information on the subject see the tech note "Reduced Cycle
Times And Lower Temperatures: Direct Power Applied To SMT Conduction Rework" at
http://www.metcal.com/tchnotes/redcyc1.html, or email [log in to unmask] for a
hard copy.
Reed Hopkins
User Development Manager,
Metcal, Inc
[log in to unmask]
(415) 325-3291
_______________________________________________________________________________
Subject: ASSY: Re: Soldering iron tip temperatures
From: [log in to unmask] at Internet-Mail
Date: 3/21/96 8:50 AM
Maurice:
IPC does not recommend tip temperatures. Suitable temperatures
should be based on recommendations of the equipment supplier and
component supplier.
IPC-R-700C, pp. 144-145, gives a number of heat-related considerations for
manual soldering. J-STD-001B, App. A, maintains that the equipment to be
used should be controlled within +/-5C of the idle tip temperature.
Mike Buetow
IPC Technical Staff
2215 Sanders Road
Northbrook, IL 60062
P: 847-509-9700, ext. 335
F: 847-509-9798
[log in to unmask]
On Thu, 21 Mar 1996, Maurice Dore * wrote:
>
>
>
>
> I'm investigating the different soldering iron tip temperatures used for SMT
>
> components. Could you please forward me information on the relevant IPC
> recommended tip temperatures for individual components and the relevant
> documentation references.
>
> Cheers
> Moss
>
>
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