Recieved the following message May, 8, 1996

>We are facing a shortage of an IEC input connector which is 
>wave soldered into our board.  The pins are tin plating over 
>copper.  The connector supplier is offering substitute parts 
>which are nickel plating over brass.  We are concerned about 
>the solderability.  Is this a valid concern?  

Yes, but a lot depends on what else you are doing in your factory.
1. Are you solderability testing with or without steam aging?  Probably not,
or you wouldn't be so concerned
2. What flux type are you using in your soldering process.  If you are using
RMA or No-Clean, I would be much more worried than if I used a highly
activated OA flux.

>Does anyone have 
>any success or failure stories regarding similar situations.  
>Any input would be appreciated.  I would also appreciate it if 
>responses could be sent direct to [log in to unmask] in addition 
>to TechNet.
>

I have many stories to tell about nickel plated parts, both good and bad,
but I will save the bandwidth for now.  Simply put, bad nickel plating
probably won't solder until the flux etches through to the base metal.  I
have seen gold over nickel over phosphor-bronze connector pins where
successive tinnings only removed more nickel until unsolderable bronze
appeared.  On the other hand, I currently build a device that uses a nickel
plated aluminum housing that we pretin and then seal by soldering.  The
pretin is performed using an old Lonco flux (CF430) no longer available. It
was designed as a lead tinning flux for hard to solder metals such as nickel
and Alloy 42.   Alpha now recommends 260HF, which i will be testing soon.
Oxidized nickel is difficult to solder to, so be aware of the age, storage
conditions, and general condition of the connector leads. 
         I am always suspicious of vendors who want to substitute parts with
wrong lead finishes.  I always wonder why he has these parts on the shelf.
During Nepcon '93, I attended a Bob Willis course on solderability testing
where some lively discussions were held.  One of the most interesting was
from several individuals from different companies that had returned parts on
reels after marking the reels for later identification if returned by the
distributor.  These individuals traded information regarding part types, lot
date codes, and markings.  They were suprised how the parts were sent from
company to company by the distributor in an attempt to get rid of the parts,
instead of dereeling the parts, fixing them, and repackaging them.
So, to protect yourself, have him tin the parts for you, or have someone
test the solderability of these parts.  Get a sample and test them with your
process.  But most of all, do your homework up front.

Good Luck, Steve Mikell, Process Engineer, Soldering & Cleaning
SCI Systems, Government Division, Plant 13
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>Regards,
>
>Pat Bailey
>Supplier Quality Engineer
>Zytec Corporation
>507 637-2966 x355
>[log in to unmask]
>
>
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