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September 2009

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Subject:
From:
Paul Edwards <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Paul Edwards <[log in to unmask]>
Date:
Wed, 30 Sep 2009 10:27:32 -0700
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Why does this always come up?

With everything that is said about the real and potential metallurgical problems with ENIG, how can ENIG be considered a good replacement for a HASLed PCB, unless you are considering only the PCB fabrication of RoHS boards or the bulk buying PCB materials ?

Look at the flatness numbers for HASLed PCBs...Unless you have huge pads and a very bad PCB fabricator the HASL thickness variation is typically no more than 0.0007" on standard part pads... That is better than the planarity on everything but LCCs and QFN type structures and well within the solder paste print height tolerances of most systems...

Besides the last time I checked we all put solder paste on pads before we stuck parts to the PCB so there is at least 0.004" of solder compliance to compensate for any bumping of the HASL...

Have built a lot of high-density high-rel PCAs and over a lot of years and I will take a HASLed PCA over any other kind of surface finish...

Paul

Paul Edwards
Surface Art Engineering


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Wednesday, September 30, 2009 7:54 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG / HASL CO-PLANARITY

Hi Lee - You might try another approach with the customer. Image that you
have a very large, nonflexible beach ball and you are trying to balance it
on your local parking lot speed bump - if you are using a HASL finish and
processing BGAs or CSPs you are doing the same procedure. Sometimes having
a visual reference is worth a pound of tolerance measurements. Good Luck.

Dave Hillman
Rockwell Collins
[log in to unmask]




Lee Whiteman <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
09/25/2009 09:09 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
[log in to unmask]


To
[log in to unmask]
cc

Subject
[TN] ENIG / HASL CO-PLANARITY






Happy Friday.

Does anyone have a reference on comparing the co-planarity between ENIG
and HASL (SnPb)? I know that ENIG is more planar than HASL, but by how
much (quantifying the argument). I'm anticipating a question from my
customer on why I want to use ENIG instead of HASL for fine pitch
applications.

Thanks.

Lee Whiteman, PMP
Senior Member Engineering Staff
L-3 Communications East
Telephone: (856) 338-3508
FAX: (856) 338-2906
E-Mail: [log in to unmask]

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