Dave,
Since we stencil print the boards, and machine place onto the stencil
printed paste coplanarity does not seem like a issue.
Other than coplanarity are there any other problems with a HASL finish?
Thanks,
Bob Kondner
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Wednesday, September 30, 2009 4:29 PM
To: [log in to unmask]
Subject: Re: [TN] ENIG / HASL CO-PLANARITY
Hi Paul - the reason the coplanarity issue comes up is that many folks
have issues with getting consistent and reproducible HASL finish
coplanarity. All of the pwb surface finishes have advantages/disadvantages
and HASL is no exception. HASL surface finishes were the primary finish of
choice for our surface mount lines for many years and as you detailed, we
also ran a very successful process. However, the inherent coplanarity of
the immersion surface finish family (ImAg, ImSn, and ENIG) is better than
HASL for our approved group of pwb fabricators. I have little doubt that
if I had more control over pwb fabricator selection, I would share your
experience but I have found that the immersion surface finish family
provides me an expanded process window for BGAs/CSPs and many of the new
Bottom Terminated Component styles (such as QFNs, ). HASL is still one of
our approved finishes but we now include the immersion surface finish
family as additional options in our "tool box".
Dave Hillman
Rockwell Collins
[log in to unmask]
Paul Edwards <[log in to unmask]>
09/30/2009 12:27 PM
To
TechNet E-Mail Forum <[log in to unmask]>, "[log in to unmask]"
<[log in to unmask]>
cc
Subject
RE: [TN] ENIG / HASL CO-PLANARITY
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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