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Reduce process variation in lead-free soldering

Connect, no. 138, September/October 2005, p.8

A board-mounted component is lowered onto a ball of molten solder for measurement
A board-mounted component is lowered onto a ball of molten solder for measurement

Many companies starting to explore lead-free solders experience problems when trying to control the wetting of components and substrates.

Failure to achieve a high quality, controllable process leads to wastage, re-working and poor product reliability.

Increasing numbers of companies are approaching TWI, seeking to avoid these problems. TWI has responded by investing in equipment to provide a better understanding of the factors relevant in the lead-free soldering process. It is also a useful tool to evaluate the effectiveness of the new lead-free flux chemistries for removing oxide and surface contamination from component terminations and PCB finishes.

This is achieved by measuring the wetting force of the solder on a particular substrate and the time for wetting to occur. A component or substrate is immersed into molten solder. The equipment then measures the force exerted on the component as the solder wets the surface.

Components ranging from though-hole to 0402 surface mount parts can be accommodated in these tests.

The testing procedure delivers a graph of wetting force versus time for a set of components. Profiling such as this leads to a reduction in process variation and increased confidence in the use of lead free solders.

TWI's solderability testing machine
TWI's solderability testing machine

For more information, please contact us.

For more information please email:


contactus@twi.co.uk