These sound very interesting.  We have had a similar problem on occasion.
Where might one obtain copies of these papers?  We have had the black
material analyzed and as I recall it was organic in nature, with trace
amounts of other in organic base materials.

Regards,

Tracy Black
Design Engineer
Microwave Engineering
MICROWAVE PRODUCTS
Gilbert Engineering Co., Inc.
5310 West Camelback Road
Glendale, AZ  85301-7597
Phone:  623-245-1050 xt 437
Fax:  623-934-5160
E-Mail:  [log in to unmask]



                    Kiiski Jarmo
                    <jarmo.kiiski@E        To:     [log in to unmask]
                    NERMET.FI>             cc:
                    Sent by:               Subject:     Re: [TN] Black nickel barrier problem w/immersion Ni/Ag
                    TechNet
                    <[log in to unmask]
                    G>


                    05/30/00 10:04
                    PM
                    Please respond
                    to "TechNet
                    E-Mail Forum.";
                    Please respond
                    to Kiiski Jarmo





Hi

There are two technical papers concidering this problem:
A Root cause failure mechanism for solder joint integrity of electroless
nickel/immersion gold surface finishes;Nicholas Biunno, Hadco; Presented at
IPC Printed Circuits Expo 1999 and
ITRI Project on electroless nickel/immersion gold joint cracking; Bruce
Houghton, Celestica; Presented at IPC Printed Circuits Expo 1999.

As far as I know, there is no fix.

B.R.
Jarmo Kiiski

> -----Original Message-----
> From: Michael Forrester [SMTP:[log in to unmask]]
> Sent: 30. toukokuuta 2000 19:43
> To:   [log in to unmask]
> Subject:      [TN] Black nickel barrier problem w/immersion Ni/Ag
>
> On a recent run of Ni/Ag boards (SM & PTH) we had solderability problems,
> especially on the thru-hole components.  Upon investigation by the board
> manufacturer,
> it was reported as a black nickel barrier problem.  Apparently this is a
> by-product of the immersion gold plating process.  What exactly is it,
> what
> causes it, and is there a way
> to prevent it?  Is there a way to "fix" a batch of boards with this
> problem?
> Thank you.
>
> Best Regards,
>
> Mike Forrester
> LeCroy Corp.
>
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