ASTM B579-73 pdf free

04-14-2021 comment

ASTM B579-73 pdf free.Standard Specification for Electrodeposited Coatings of Tin-Lead Alloy (Solder Plate).
The use of automated testerseliminates possible operator errors and assures repeatableresults; in these units,the dipping operation,temperaturecontrol,and timing sequences are automated. One availableunit provides a means for testing flat surfaces,wires,andcomponent terminations by vertical immersion into the solder;in addition, a holding fixture is available to lower wire sampleshorizontally and face down through the solder, the speed ofrotation being varied to produce a range of immersion times.Progressively increase contact times with the solder usingseparate specimens, and determine the least time required forcomplete wetting and the onset of dewetting by visual exami-nation of the series of specimens. The best conditions ofsolderability would have the shortest wetting time, and would show no signs of dewetting within the longest contact timerequired. A minimum wetting time under 2 s is evidence of good solderability.An auxiliary attachment is available for thedetermination of spread values. The specimen is lowered ontothe surface of the solder and a delay timer built into theequipment holds the test piece in contact with the solder forany preselected time up to 10 s. Determine spread values as in9.3.4.This method involves placement of a fixed volumeof solder on the surface of a specimen with a few drops of rosinflux (Type W flux,MIL-F-14256) and heating the specimen fora fixed period of time at a controlled temperature. The area of spread can be measured with a planimeter. This test method was devised for assessing thesolderability of wires,component leads etc.This method consists of lowering the specimen ofwire (or component lead) previously fluxed, horizontally ontoa molten globule of solder, which is thereby cut in two. Thetime in seconds for the solder to flow around the wire and uniteabove it is a measure of the solderability.Use a fresh pellet ofsolder for each test, the size of the pellet being determined bythe diameter of the specimen wire.Commercial test machinesare available.Artificial Aging (When Specified By the Purchaser) Place the sample for test in a suitable vessel aboveboiling water and leave it there,with the water boilingcontinuously, for 24 h.Keep the vessel covered and ensure thatthe sample does not come into contact with the wall of thevessel and that its lower edge is not less than 50 mm (2 in.) ormore than 100 mm (4 in.) above the surface of the boilingwater. Arrange the cover on the vessel and the steam con-denser, if used, so that they do not discharge condensed waterover the sample. Disregard any discoloration of the sampleoccurring during this aging treatment.After the 24-h treatment,remove the sample from the steam and allow it to dry in the air. Test methods outlined in 9.3.2,9.3.3,9.3.4, or 9.3.5are used to assess the solderability of the aged specimens.ASTM B579 pdf download.

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