TechNetters, it has been some time since the subject of bare board shelf appeared on TechNet. As you probably know, IPC published IPC-1601 in August 2010, which discusses printed board storage.

IPC-1601 has some comments on HASL finish, referring to a technical paper which, I presume, was based on data. It mentions 8-9 month degradation of solderability in 'thin' areas of coating, with other areas degrading in 1-2 years. If my reading is correct, 1601 says the degradation 'plateaus' after these times, indicating that solderability deteriorates little after these storage periods. It does not say anything like 'solderability will be questionable' or 'it may be difficult to form an acceptable solder joint on boards stored for more than (X) months'.

Information on ENIG and Immersion Silver in 1601 is more limited than that for HASL.

I am trying to develop a shelf-life policy for this company to use, thinking that some official policy is better than none.

May I have comments on storage and shelf life of boards finished with HASL, ENIG, and ImAg? If anyone is interested, our storage area does not have climate control. I estimate the minimum temperature is at least a little greater than 10 C, maximum temperature is less than 30 C.

Louis Hart
Compunetics
Monroeville, PA
USA
[log in to unmask]<mailto:[log in to unmask]>
412-858-1272

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