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September 2011

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Subject:
From:
Inge Hernefjord <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Inge Hernefjord <[log in to unmask]>
Date:
Thu, 15 Sep 2011 23:27:50 +0200
Content-Type:
text/plain
Parts/Attachments:
text/plain (276 lines)
no  RF... and no bananas ...

the bad reputation of ENIG, does it not belong to history now?  I used to
get ENIG issues on my desk once a week, but have not heard of any problems
for years. Probable cause is that they buy lots and that there is a
stringent quality/process control, not only in a bunch of papers,* but in
the daily routines.* Our purchaser or the component guy knows that he can't
sit in his chair all day, but got to visit the board maker frequently. A
ticket to Shanghai or Tokyo or like costs less than a handful of PWBs.
Don't tell me that your company is a small one, then the reason for personal
contacts is even more worthful. Standing still one week can be catastrophic
for a small entrepeneur with only one source and only one product,  while a
mega one can redirigate to another plant in the country or abroad.

I've heard that american electronic engineers  in general are little slow
when it comes to 'benchmarking' , but I do not know  if it's true.

//Inge


On 15 September 2011 22:40, Phil Nutting <[log in to unmask]> wrote:

> Ok, so we use SMT and PTH circuit boards, all are low speed (20 kHz to 50
> kHz), no BGAs, smallest parts are typically 0603, no Bluetooth, no RF,
> typically 0.015 pitch.  Environment might be a medical office, airport,
> semiconductor fab or research lab.
>
> As for all the geniuses getting together to decide... I'm it.  There is no
> one else that has in depth knowledge of all the possible factors.   I guess
> I could go out to lunch and discuss it with myself over a couple of
> martinis.  Yum!
>
> Phil
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
>  Sent: Thursday, September 15, 2011 3:19 PM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG versus LFHASL
>
> Regarding my previous post, I am not saying anyone should not use ENIG. You
> just need to be knowledgeable in ALL surface finishes before you make a
> selection.
> Surface finish is not something you pull out of your hat based just on
> whether the CCA is going to be lead-free, although that is definitely one of
> the factors.
> For example, you need to consider the type of circuitry. If it is an
> analog, high RF, Bluetooth CCA for example, ENIG would be your last choice
> (it may be too lossy, and if you do not understand what that means you
> should not be determining the surface finish alone).
>
> If it is a double sided SMT CCA with BGAs on both sides, with through-hole
> parts that require hand soldering, and must be processed using lead-free
> solder, why then, ENIG might just be the best choice. Or it might not. In
> that case, OSP is definitely not the best choice.
>
> Selection of finish should be left to a team of engineers who know all of
> the advantages/disadvantages of each finish and understands (intimately)
> his/her particular circuit design types (RF receiver/converter, digital
> processor card, power supply card, D/A card, thermoswitch device, etc,) and
> there are many to consider. The designer, process engineer, and quality
> engineer should also be familiar with the fabrication capabilities (or
> conversely, the weaknesses) of the different fabricators they have a
> business relationship with, and have that in mind when selecting a finish
> also.
>
> It is definitely NOT something a manufacturing engineer alone should decide
> based solely on process type or "personal favorite".
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
> Sent: Thursday, September 15, 2011 1:37 PM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG versus LFHASL
>
> In fact, Werner wrote entire papers about the possible problems with using
> ENIG. Here are some;
> http://content.yudu.com/Library/A1qwqg/GlobalSMTampPackagin/resources/61.htm
>
> http://www.trafalgar2.com/documents/Issue_Archive/global_7.3_us_opt.pdf
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Reuven Rokah
> Sent: Thursday, September 15, 2011 1:19 PM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG versus LFHASL
>
> I am in favor of LFHASL because of its robust in processes and storage
> conditions. You just have to choose the right alloy in the HASL process.
>
> You can search in the IPC archive and read Werner recommendations, he was
> favor of Immersion Silver and against ENIG because of the Ni3Sn4 IMC layer,
> High thermal energy (15 degC) at reflow soldering, lnferior electrical
> properties of solder joints and other reasons such solder  d black pads.
>
> Reuven
>
> On Thu, Sep 15, 2011 at 8:00 PM, Phil Nutting <[log in to unmask]
> >wrote:
>
> > Hello Technetters,
> >
> > We are having a discussion about the merits of both ENIG and LFHASL.
> > In
> > 2006 when we switch to a RoHS compliant process we evaluated many
> > board finishes and decided, for our volumes, that although ENIG was
> > more expensive it was more robust.  LFHASL wasn't ready for prime
> > time, Immersion Silver was great but required careful storage and
> > handling, OSP was not something that fit our process.
> >
> > Now that LFHASL appears to be more main stream we are reconsidering it.
> >  ENIG is not always done in-house at some of our fab shops, so that
> > adds time and money to the delivery.  These shops now have LFHASL
> > in-house, so there is a potential for some savings here.  We have been
> > given stories of storage issues with LFHASL and other concerns too.
> >
> > As I recall, the industry recommended method of storage of bare
> > circuit boards is in a sealed bag with desiccant, regardless of board
> finish.
> >  Leaving bare boards unwrapped and in an open bin is just plain bad
> > practice especially if near the ocean.
> >
> > Several of us here think LFHASL is now right for our processes.
> >
> > Please advise if we are off base.
> >
> > Phil Nutting
> > Design for Manufacturing Engineer
> > Kaiser Systems, Inc.
> > 126 Sohier Road
> > Beverly, MA 01915
> > Phone: 978-922-9300 x1310
> > Fax: 978-922-8374
> > e-mail: [log in to unmask]<mailto:[log in to unmask]>
> > www.kaisersystems.com<http://www.kaisersystems.com>
> > www.linkedin.com/in/philnutting<http://www.linkedin.com/in/philnutting
> > >
> >
> >
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>
> --
>
> Best Regards,
>
> *Reuven Rokah*
>
> Mobile: 972-52-60-120-18
> Tele-fax: 97239360688
> <http://www.rokah-technologies.com/>[log in to unmask]
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