looking for HASL TIN thickness specification

You should have a few microns of Sn on a board.

Vlad

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IPC-6012 Table 3-2. States "Fused tin-lead or solder coat - Coverage and Solderable". The lack of any specific dimension criteria doesn't make this any less a requirement. There must be complete coverage of solder on the land, and it must be wettable.

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At a former employer we required HASL thicknes to be a minimum of 0.75 micron (30 microinches), as measured at the thinnest point on any given pad. This would generally assure a minimum 1 year solderability shelf life. Usually when we saw a solderability problem, we found HASL thickness to be less than 0.25 microns, or the boards to be very old. Assuming the starting Copper pads were clean, the HASL process would produce an IMC layer with a starting thickness of typically about 2 microns. The IMC (Cu3Sn and Cu6Sn5) is readily solderable unless oxidized by exposure to the atmosphere. The HASL coating prevents this oxidation, but it is not completely impermeable to Oxygen. Thus, the limited shelf life, depending primarily on HASL thickness, time, and storage temperature.

Glenn

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Not sure why you would... but here are a couple of links that may help if you are having manufacturing problems

http://www.smtinfo.net/docs/Electronic%20Production/9.htm

http://www.midwestpcb.com/capabilities/plating2.html

Granted I only have a Masters from Purdue, and been in this business for over 20 years.....

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