[SI-LIST] Re: Immersion gold
- From: "szimmer" <szimmer@xxxxxxxxxxx>
- To: <brian.p.moran@xxxxxxxxx>, <leeritchey@xxxxxxxxxxxxx>,<si-list@xxxxxxxxxxxxx>, "Martin Euredjian" <martin@xxxxxxxxxxxxxx>
- Date: Tue, 15 Apr 2003 10:38:33 -0400
Another possible alternative is to use an Organic Solderability Preservative
(OSP). This is applied to the bare copper surface after Soldermask,
typically just prior to shipping. This thin coating has very good
coplanarity and is less expensive than some of the alternatives previously
mentioned.
----- Original Message -----
From: "Moran, Brian P" <brian.p.moran@xxxxxxxxx>
To: <leeritchey@xxxxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>; "Martin Euredjian"
<martin@xxxxxxxxxxxxxx>
Sent: Monday, April 14, 2003 8:44 PM
Subject: [SI-LIST] Re: Immersion gold
>
> Martin,
>
> Folks are always looking for ways to improve the coplanarity or =
> smoothness of SMT pads as we go to smaller and smaller geometries. You =
> have to coat the exposed pads after plating and the soldermask is =
> applied with something to keep the exposed pads from oxidizing, and for =
> the solderpaste to adhere to. The cheap and dirty approach is to dip the =
> board in tin/lead solder and then blow off all the excess. Of course =
> this can leave puddles and rough surfaces. So various alternatives have =
> been attempted over the years to coat the bare platting pad surface. I =
> forget the names of some of the coatings people have tried to make work =
> with mixed results. The last time I was involved in such discussions =
> people were looking at immersion gold, which is expensive, or immersion =
> tin, which was discussed as a lower cost alternative to immersion gold. =
> Not sure it ever caught on or what the trade offs were. In either case =
> case the object is to prevent the pads from oxidizing while maintaining =
> optimal flatness.=20
>
> Brian P. Moran
> Signal Integrity Engineer
> Intel Corporation
> brian.p.moran@xxxxxxxxx
>
>
> -----Original Message-----
> From: Lee Ritchey [mailto:leeritchey@xxxxxxxxxxxxx]
> Sent: Sunday, April 13, 2003 1:26 PM
> To: si-list@xxxxxxxxxxxxx; Martin Euredjian
> Subject: [SI-LIST] Re: Immersion gold
>
>
>
> Martin,
>
> The proper term for this kind of PCB finish is immersion gold over
> electroless nickel (ENIG). It is a "noncorrosive" finish applied after
> solder mask has been applied over bare copper.
>
> It is a way to maintain solderability of the pads and holes. White =
> nickel
> is not a substitute for this finish.
>
> The ENIG process can go unstable and produce a black pad failure. A =
> safer
> finish is electroplated gold over electroplated nickel.
>
> Lee
>
> Lee Ritchey
> leeritchey@xxxxxxxxxxxxx
> Why Wait? Move to EarthLink.
>
>
> > [Original Message]
> > From: Martin Euredjian <martin@xxxxxxxxxxxxxx>
> > To: <si-list@xxxxxxxxxxxxx>
> > Date: 4/12/2003 12:06:46 PM
> > Subject: [SI-LIST] Immersion gold
> >
> >
> > Can someone explain the primary need/benefits of the immersion gold
> process?
> > Some have told me that "white nickel" is comparable in certain =
> aspects.
> >
> > Thanks,
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Martin Euredjian
> > eCinema Systems, Inc.
> > voice: 661-305-9320
> > fax: 661-775-4876
> > martin@xxxxxxxxxxxxxx
> > www.ecinemasys.com
> >
> >
> >
> >
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