It's late to say thank you, Georg Milad,
but better late than never as they say on Greenland.

Someone from Shipley have been here together with the PWB maker concerning a
superlarge BGA soldering problem. We have learnt a lot since september but
there remains issues still. What you said below is typical for most articles
and specs: layer thickness and phosphorous but little about foreign stuff
that can appear (even for the best in the game it seems), such as fenoxy,
epoxies, glycols, hydrates, carboxyls and a lot more. We made a TOFSIMS on
some board lands and found SiCH3, C2H3, C3H7, Fe, C5H9, In, SnOH, just to
mention an example. And added to that comes the morphologic aspects and
about microhardness and boundaries and size and shape of Nickel domes.

I thought I had learnt a lot about the BGA soldering, but suddenly I feel
how empirical a lot seems to be. "We use to..." or "We think that..".
Understand that too, but would like something more in the spec than just
thickness and P%.

If there is something I can hang up on the wall, and tell people 'this is
how a solder pad is being done' I would be vary glad. Guess all other
Ericsson groups agree (in silence, of course)
Best regards

Ingemar Hernefjord
Ericsson Microwave Systems

PS. Isn't Steph Meschter within Lockheed Martin any more or did he sign off?






-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: den 6 september 2000 21:04
To: [log in to unmask]; [log in to unmask]
Cc: [log in to unmask]
Subject: Re: [TN] Increased Phosphorus in Electroless Ni


Here is my two cents worth on the topic of Electroless Ni , Phosphorous
content.
Here at Shipley our recommendation for thickness of Electroless Ni is 100 to

250 uins or 2.5 to 6.0 microns.  For the gold thickness we recommend 2 - 4
uins (0.05 - 0.10 microns) as the best thickness to protect the Ni during
storage and not to create any Ni defects during processing.
As far as Phosphorous content in the Ni deposit we are presently staying
with
7 -9% P.  We have seen data, where High phos (10 - 12%) and Low phos (5 -7%)

gave equally good results, with regards to incidences of "Black Pad".
Our tests indicate that High Phos is prone to skip plating and gold adhesion

failure.
The IPC Plating Subcommittee 4-14 will be meeting in Miami, during IPC Works

2000, at 1:30 to 3:00pm on September the 11th, 2000.  The agenda of the
meeting is to define an IPC-Standard for Electroless Nickel and Immersion
Gold as well as Electroless Gold, as surface finishes widely used in the
industry today. Anyone interested in participating is welcome to join the
meeting or send his input to me, and I will keep him or her informed of the
committee progress.
George Milad
Tech Marketing Mgr.
Shipley Ronal Inc
Chairman IPC Subcommittee 4 -14

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