| A tester for measuring the surface tension of solder alloys has been developed by using the wetting balance method, which can acquire the accurate data in a fully quantitative way. In the modern electronics industry, packages and pitches of conductor and solder land are becoming smaller and smaller due to the miniaturization of components. Consequently, the parts suffer problems such as the displacement of minute chip components and solder bridging to short-circuit the neighboring conductors on a printed circuit board. These problems are associated with the surface tension of molten solder alloy. Furthermore, the use of lead is going to be regulated in the electronics industry because of its toxicity. Therefore, researches to develop new lead-free solders that do not contain lead have been pursued. From these points of view, it is impendency to develop the Wetting Balance Tester, which can measure the surface tension of solder alloy easily.A non-wetting rod is immersed into a molten solder bath at a fixed speed in the Wetting Balance Tester, while the load cell and the amplifier collecting the data, PC processing the data at the same time. Later, the data been processed by PC are used to evaluate the wettability performance of solder alloys. The Wetting Balance Tester includes the motion system, the temperature control system, the testing system and the data processing part.Sn-37Pb, Sn-0.7Cu and Sn-3.5Ag are three important metallic solders with lead free. We use the Wetting Balance Tester to measure their surface tensions in the air atmosphere and in the nitrogen atmosphere respectively. Afterwards, comparing the data got from these experiments with the published data, we can know that the Wetting Balance Tester is rather reliable.
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