Have any of you experience with the MacDermid process Sterling as a alternative to Alpha and electroless Ni/Au.
I made some test comparing the wetting balance. The result was a better wetting than even HASL and much better than Ni/Au
Jacob Ransborg
----- Oprindelig meddelelse -----
Fra: Paul Klasek <[log in to unmask]>
Til: <[log in to unmask]>
Sendt: 9. juni 1999 01:53
Emne: Re: [TN] Immersion Silver [HASL Alternatives] <IPC TN>
> Hi Mike
>
> As I said ; I'm stuck with NiAu because of the switch pads ;
> I tested the Alpha Level(which Neil made sure he did not mention)just from
> curiosity, for life (vacuum packed); solderability ; and abrasion, on
> switching ; all in line with what Kathy reported .
> However ; being as good as it is (good enough); I agree with Neil as well it
> does tarnish more readily than tin .
> Mind you again ; I did not find the tarnish (greasy fingerprints mainly)
> impeding the solderability to noticeable degree.
>
> It must be actually a real hasl of a pick even from fab folks investment
> point of view (crossroads) ;
> as here one major house invested to silver ; while other came to me with tin
> samples ; and my HK buddy is doing nothing but gold .
>
> The solid deposit I went through ages back ; again the switching precluded
> me from implementation ;
> it must have it's uses (some positive feedback sits in archives); not for
> efficiency freaks like me .
>
> It really depends on applications ; on mass telephone phenolics the organic
> copper did fine as well .
> There 's nice and simple "finish line" page 13 in IPC Review (June 99) ;
> giving the trends vectors so far .
>
> See you
>
> Paul Klasek
> http://www.resmed.com
>
> -----Original Message-----
> From: [log in to unmask] [mailto:[log in to unmask]]
> Sent: Wednesday, June 09, 1999 12:38 AM
> To: 'IPCtechnet'
> Subject: Re: Immersion Silver [HASL Alternatives] <IPC TN>
>
>
> Kathy, Paul-
>
> We've started looking into Immersion Tin (Dexter's FST) and solid solder
> deposit [Masktek, in Anaheim CA, and SiPAD [licensed from Siemens], through
> board supplier MPCS, in Round Lake Beach, Illinois). I have to admit to not
> considering/knowing about immersion silver.
>
> A paper on immersion tin was presented at IPC PC EXPO'99, at Long Beach
> earlier this year, co-authored by Dexter Elec Materials and DSC Alcatel
> (TX). The test data presented by the user is worth checking out.
>
> Have you considered these as alternatives to HASL [what an appropriate
> acronym!]? In HASL's defense, "...nothing solders like solder.", an
> observation from a supplier of an alternative finish. And, HASL has served
> it's purpose up to the realm of fine pitch SMT patterns [pitch > 0.5
> mm/.0196.. inch].
>
> NOTE: the May 1999 issue of Circuits Assembly Magazine has a concise, well
> written article on alternative finishes, by Matt Kehoe of MPCS.
>
>
> Check out sites...
>
> http://www.dexelec.com/pwb/products/advanced_process/plating_tech.html
>
>
>
> http://www.midwestpcb.com/sales/fullnasa.htm
>
>
>
> http://www.masktek.com/our_products.htm
>
>
> -Regards,
>
> Michael Alderete
> Aerojet, Azusa CA
>
>
>
> you wrote...
> ----------------------------------------------------------------------
>
> Date: Mon, 7 Jun 1999 16:56:07 -0700
> From: Paul Klasek <[log in to unmask]>
> Subject: Re: Immersion Silver
>
> Concur with Kathy on all points .
> On the switching (contact points) we tested with no resistivity changes on
> carbon pill mounted in silicon pad action up to 50K cycles before we got
> down to copper .
> On the contact however ; once you wear the organic from top ; it does
> oxidize ;
> therefore unsuitable for more repeated low force low current switching . OK
> for edge con's in commercial applications , just.
>
> Which was the only reason why we keep NiAu ; which is not such a dream to
> solder ; as we have the silipad switching .
>
> Paul Klasek
> http://www.resmed.com
>
> -----Original Message-----
> From: Kathy Palumbo [mailto:[log in to unmask]]
> Sent: Tuesday, June 08, 1999 9:35 AM
> To: [log in to unmask]
> Subject: Re: [TN] Imersion Silver
>
>
> Charles,
>
> I did an extensive analysis (temperature cycling, vibration, humidity, lead
> pull testing, and cross sectioning) on completed assemblies with this
> coating on the PCB prior to approving it as an alternative coating to HASL.
> I found that the coating is a direct drop in replacement to HASL. In other
> words you can use the coatings interchangeable with no problems. The
> storage life is equivalent to HASL. The coating has no special handeling,
> or storage requirements. Keep in mind that if you are using the coating on
> your PCB as a contact point (i.e. a KEY BOARD) then the silver immersion
> coating is not the way to go (too thin). If you intend to solder to the
> coating, then it is not a problem.
>
> We have been using silver immersion as an alternative coating to HASL for
> more than 1 1/2 years with no problems. The wetting action of the solder to
> the pads was better than HASL coated PCB's, and the cross sectioning of
> several solder joints showed an even better fill of the solder under the
> leads than with HASL (which had quite a few voids). The biggest advantage
> was the elimination of bridging issues on fine pitch devices caused by the
> variance of the HASL deposit. We have virtually eliminated all of our
> bridging issues on fine pitch devices. This includes our PCMCIA Fax Modem
> product, which use to be our worse yeild and now is one of the best.
>
> Contact Steve Biegle with Alpha at (219) 922-7990. He has a lot of good
> data which you can review and use to set-up your own testing/evaluation
> process.
>
> If you have more specific questions regarding the testing I did you can
> contact me direct.
>
> Good Luck!!
>
> Kathy Palumbo
> Manufacturing Engineer
> Viking COmponents
> BUS.: (949) 643-7255
>
> ----- Original Message -----
> From: CharlesC <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: 07 June 1999 14:33
> Subject: [TN] Imersion Silver
>
>
> > Once again I need help.
> > I am looking for information on Alpha Metal's "AlphaLevel" Imersion
> silver
> > deposition. I have never built boards made with this process and would
> like to
> > know what experience anyone else may have had with this (good or bad ).
> The PWB
> > is mixed, some through hole mostly surface mount. I would especially like
> to
> > know about solderability and storage life.
> >
> > Thanks in advance.
> >
> > Charles Caswell
> > Process Lead,
> > Printed Circuit Board Dept.
> > Frontier Electronic Systems
> >
>
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