Quality Test Procedure for Desoldering Braids (Wicks)
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prepared by and copyright for by Ernest Spirig DE-SOLDERING with a wick is actually SOLDERING the wick with the solder to be removed . Solderability is therefore a reliable test to predict the desoldering "power" of a wick . A Desolder Wick (or braid) is a copper mesh pre-coated with a flux of natural or synthetic rosin. Desolder Braids are available in various widths to fit the desoldering task area. The different wick width means differentthermal masses or different heat flow needed to bring the wick to the melting temperature of the solder to be removed. > The wick end is placed on top of the solder to be removed. A hot soldering iron tip is pressed from top onto the wick. The wick heats up and the highly heat conductive copper braid of the wick conducts the heat to the solder and melts the solder if heat supply is sufficient. The heat source must heat up the copper mass AND thesolder mass simultaneously. The heat source must be able to quickly supply the neededthermal calories to the job. The heat source must therefore correspond to the wick size. The heat source is normally the heated tip of a solderingiron. > Quick and undelayed heat transfer stems from the heat stored in the thermal mass of the hot copper tip and only secon-dary from the available continuous heating power (wattage) of the iron. A geometric too small tip size compared to the wick width will be (even if set to an increased soldering temperaturelevel) immediately cooled below the melting temperature and this obviously means unsatisfactory desoldering action or no desoldering action at all. Ideally, a soldering iron tip will have a chisel like shape and the tip width should be at least as wide as the wick width.This rule is a good fit for almost any desoldering task. The soldering iron should be a thermostatic or electronic tempera- ture controlled unit. and the temperature set on the iron temperature control to 320 C or temperature code 8 on aWeller TCP iron version. >

Testing a desoldering braid with a soldering iron gives a quick and rough idea of its function (good / no good) but willgive no "measurable" results, or results which can be easily verified or repeated by the same test set-up.Spirig has used the Solderability definition in nearly 35 years (2004) of wick manufacture as its internal quality controland audit instrument. Due to the unavailability of a commercial solderability tester in the late 60's, Spirig designed such a tester). The Solderability Tester received a US patent 4,227,415.Today solderability testers are available with similar or...

Upon impact with the molten solder surface the wick will push the solder surface down (negative). After a short delay(time until wick is enough heated up from solder bath to start its own fluxing activity), the solder surface will turn into an upwards positive curve.The capillary forces of the wick surfaces / interstices do draw the solder into the wick end and if solderability of thewick surfaces is satisfactory it will will even lift the solder level penetrating the wick more or less above the fluid solder level in the pot.This solder flow into the wick can be easily seen and allows a...