Page 17 - PACE Katalógus

Lead Free

Working with Lead Free
solders

Lead Free solders do not behave or look like their lead containing counter- When using Lead Free solders, regardless of alloy, it is absolutely imperative
parts. As our industry changes over to Lead Free solders, individual PCB that tips are properly maintained, otherwise tip life will be reduced significantly.
assemblers will need to address several issues relating to hand soldering and Tips should be cleaned frequently to remove oxidation before it becomes
rework. These issues include: impossible to remove. Tips should always be tinned when not being used,
otherwise oxidation will quickly form on the tip. If the iron will not be used for
• Higher melting temperatures – which mistakenly lead to extended periods of time, they should be turned off.
operators increasing equipment operating temperatures. Higher
operating temperatures do not make the process quicker, they can The use of equipment with SetBack and Auto-Off functions (standard on all
actually slow it down. PACE equipment), is very desirable. Additionally, optional accessories such as
PACE’s Tip & Tool Stand with Instant-Setback ensure that tip life is maximized.
• Poor wetting and spreading properties – Additional time is The Tip & Tool Stand with Instant-Setback puts the system into “SetBack”
required when working with Lead Free solders, they do not spread or after 45 seconds of inactivity. When the iron is removed from the Tip & Tool
wet like lead containing solders do. Operators must slow down. Stand, it restores itself to the set temperature almost immediately.

• Difficult to work with – Bridging and insufficient solder defects The use of nitrogen assisted soldering equipment helps to mitigate the
are common, even for experienced operators, leading to operator problems associated with using Lead Free solders. Nitrogen helps on two
frustration and poor quality. fronts. First, it creates an inert environment around the soldering tip, reducing
the potential for tip to oxidize. Second, it assists in the soldering process at
• Dull grainy finish – makes inspection difficult. the PCB level by purging oxygen from the immediate area which reduces or
eliminates the formation of oxidation on the work site. This not only reduces
Because Lead Free solders oxidize quickly, more aggressive and longer lasting the amount of flux that is required, but it also helps to improve wetting,
fluxes are required to keep surfaces clean and free from oxidation. Working spreading and leaves a finish that is shinier and less grainy.
with no-clean fluxes is challenging as their process window is often small.
Once they are burned off, oxidation immediately begins to form which can PACE’s nitrogen assisted soldering systems pass the nitrogen through or
result in a marginal or defective solder joint. Additionally, increasing operating around the heater before it is directed to the work site. This “pre-heats” the
temperatures creates an ideal environment for oxidation to form and will also immediate area which can also help to reduce thermal shock to component
lead to flux and solder ball splatter on the PCB. If the flux is splattered all over leads and to components themselves. Pre-heating also allows for the use of
the PCB, it’s not able to do its job on the surfaces to be joined during the lower, safer and more effective soldering temperatures.
soldering process.
PACE’s soldering systems offer legendary thermal control as well as advanced
Lead Free solders also affect soldering and rework tools and their effect is features to maintain your process. Unique PACE features such as IntelliHeat,
detrimental. Lead Free solders contain high percentages of tin, almost always Power Modules and password protection ensure consistency and quality
over 94%. Tin is a corrosive and active metal. When it mixes with iron (the in your process. Economical tips and standard features such as “SetBack”
protective layer on soldering tips), an inter-metallic compound is formed that and “Auto-Off” maximize tip life to reduce operating costs and increase your
wears away more quickly than the iron would either by itself or when used bottom line.
with lead containing solder. This causes two problems, one is shorter tip
life as the protective iron coating is dissolved in the tin, and the second is
that oxidation forms more quickly which is further exacerbated by the high
temperature environment the tips work in. As a result, tin oxides form and
create an inter-metallic compound with the iron plating on the tip. Once the
oxidation begins to form, the tip will lose its ability to wet with solder and if
not cleaned off quickly, it becomes almost impossible to remove and the tip
must be replaced.

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