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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.

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