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November 2005

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Subject:
From:
"Dehoyos, Ramon" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dehoyos, Ramon
Date:
Thu, 10 Nov 2005 10:33:36 -0500
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        Hi Steve:
                        Could a database of gold plated lead parts that have been used in the past be created? Maybe your software system will allow  to see which parts have had the leads dipped in solder pots to remove the gold. Perhaps if stock could be flagged when a part that just arrived matched one in that data base and be processed accordingly. Sometimes by adding one extra person to look into special cases like this will save a ton of time. A person that would check that the entire kit is ready to roll. Latest stencil rev or the appropriate stencil rev, parts prepped, .......
        Regards,
        Ramon 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Thursday, November 10, 2005 9:37 AM
To: [log in to unmask]
Subject: [TN] Gold plated components, what a pain!!

Good Mornin' Everyone!

We've got a little problem here that I think everyone goes through, and maybe I can get some pointers on how to deal with it.

J-STD-001 states that:

3.9.3 Gold Removal

Gold shall be removed:

   From at least 95% of the surface to be soldered of the through-hole
   component leads with 2.5 ìm [0.0984 mil] or more of gold.

   From 95% of all surfaces of surface mount components to be soldered
   regardless of gold thickness.

   From the surface of solder terminals plated with 2.5 ìm [0.0984 mil] or
   more of gold.

A double tinning process or dynamic solder wave may be used for gold removal.

Electroless nickel immersion gold (ENIG) finishes on PCBs are exempt from this requirement.

These requirements may be eliminated if there is documented objective evidence available for review that there are no gold related solder embrittlement problems associated with the soldering process being used.

I have no problem with the requirement, and I understand why the requirement is there, but the problem that we're having is that these gold plated parts sometimes are discovered only when they've been pulled for a work order to be released for production, or even worse, when they are being loaded on a feeder during machine set-up.

"Hey Steve, we got a gold plated part here!" So the set-up will be delayed, or the assembly will be built short and then the gold plated part hand-soldered later after the gold has been removed depending on how urgent the schedule is.

We try to catch these gold plated parts in parts in receiving, if they can be identified there. But there are many parts are coming in sealed, and we've discouraged sealed packaging from being opened until it is used.

Our manufacturing engineers say that they can't identify every single part that is gold plated without going through the datasheet of every single part, or calling the component manufacturer, which there isn't enough hours in the day for them to do.

On top of the problem trying to identify the parts before they hit the SMT line, there is the difficulty of actually removing the gold from some of these little beasts because of the size and geometry. For example, look at:

http://www.stevezeva.homestead.com/LEDFootPrint.jpg

How do you go about removing the gold on something like that? JANTX transistors are another one...

We've got a few customers that are giving indications that they might start banning 100% tin plated components unless they've been tinned with standard tin/lead solder which will only intensify the problems that we're seeing now.

I'm just wondering how everyone else deals with this? I'm open for anything...any suggestions at all.

Kind regards,

-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX

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