IPC-TR-462 "Solderability Evaluation of Printed Boards with Protective 
Coatings over long Term Storage"  established that boards with good 
solderability would last up to 2 years. I have included details from a 
May 95 response to a technet question.

Regards, Dave Bergman, IPC

Date: Mon, 15 May 1995 09:16:52 -0500 (CDT)
From: David Bergman <[log in to unmask]>
To: MR DOUGLAS C JEFFERY <[log in to unmask]>
Cc: [log in to unmask]
Subject: Re: Tin/lead plating vs HAL

In the IPC technical report IPC-TR-462 (1987)  Solderability Evaluation 
of Printed Boards with Protective Coatings Over Long Term Storage, after 
a 2 year storage period the report concludes:

"3. Both tin-lead plated and solder coated boards echibited good 
soldering performance after two (2) years of storage.  The solder coated 
boards were more consistent;  however, the solder plated boards 
exhibited higher ratings.  Copper-only boards, protected by organic 
coatings, did not solder as well."

Please note that there has been significant improvements in organic 
coatings since 1987.  Also to consider, the use of HASL instead of 
tin/lead plate should decrease the amount of lead waste.

The IPC-TR-462 report is available from IPC for $27 for member companies 
and $55 for non-members.

Regards
***************************************************
David W. Bergman, Director of Technical Programs
IPC
7380 N. Lincoln Avenue
Lincolnwood, IL  60646
708-677-2850 x340 Phone
708-677-9570 Fax
email  [log in to unmask]
***************************************************


On Thu, 11 May 1995, MR DOUGLAS C JEFFERY wrote:

> -- [ From: Douglas C. Jeffery * EMC.Ver #2.10P ] --
> 
> 
> I recently had a customer inquire about the advantages or disadvantages
> of using tin/lead plating over HAL for a connector application (SIMMs).
> We have been 100% HAL for several years and I couldn't really answer
> his question other than to say we don't have a tin/lead bath...So..Are
> there any thoughts as to one method being preferred over the other? 
> (note. the question is about the insertion tabs not component
> attachment, and he currently is not using ni/au).
> 
> Thanks for any insight.
> 
> 
> Doug Jeffery
> Electrotek, Inc.
> [log in to unmask]
> 414-762-1390
> 
> 
> 




 On Fri, 2 Jun 1995, Houle, Terry R 
@EAG wrote:

> 
> I am looking for input on what is felt to be a reasonable timeframe to store 
> unpopulated printed circuit boards with a HAL finish?  This is assuming no 
> extraordinary storage conditions. Looking to avoid/minimize solderability 
> problems during population.
> 
> 
> Terry Houle
> Loral Defense Systems-Eagan
> 
>