In case you guys haven't had a chance to see it yet, there's a great
article in January's issue of CircuiTree regarding ENIG and black pad. It
states, among other things, that those of you who are dealing with a
modified general metal finishing bath (as most are) will most likely suffer
some amount of black pad (in essence, regardless of phosphorous
content). The cause of the black pad phenomenon has been found and fixed,
and it has nothing to do with phosphorous.
Mark Mazzoli
At 04:42 PM 1/22/01 +0100, you wrote:
>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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