George,
Thanks!
brgds,Ricardo (not Roberto)
>>> "Wenger, George M. [Contractor]" <[log in to unmask]>
09/07/2014 19:24 >>>
Hi Steve,
I know the attachment to this email will be stripped off by TN but I
assume that since your email is also on the distribution you will get
the attachment and might be able to post it for others to see.
The first slide in the attachment one of Roberto's photos and since I
didn't know if this was vertical or horizontal HASL I put two images on
the slide indicating what I think was the HASL direction and the air
Knife directions. You are correct that this does look like "typical
HASL" One of the problems with HASL is you can't look at a HASL surface
finish on a pad and be certain if it is solderable or not. I've always
over simplified HASL by saying you can have FLAT HASL by blowing hard
with the HASL machine air knives or you can have SOLDERABLE HASL by not
blowing hard with the HASL machine air knives but you then typically
have topography issues which effect fine pitch component solder paste
printing and placement. The real trick with HASL is to blow hard enough
with the air knives to level the HASL surface finish but not blow TOO
HARD to remove all of the solder and leave IMC. That means the PCB
fabricator doing the HASL surface finish has to pay lots of attention to
his HASL process.
I assume from Roberto's photos that Location I marked as Location #1 is
solderable because there looks like thick solder in that area. The
Location I marked as Location #2 may or may not be solderable. If you
do an XRF measurement in that area and fine you have 20 to 50
micro-inches of solder the chances are you have IMC and will have
solderability issues. If the XRF measurement indicates you have over 50
micro-inches of solder the features will probably be solderable. My
preference has always been that I want at least 100 micro-inches of
solder on a HASL feature to insure that it will be solderable.
The second slide in the attachment is a really old analysis of a SnPb
HASL board where there were solderable and non-solderable areas on a
HASL feature.
My suggestion to Roberto is if he is concerned he should do XRF
measurements because they are easy, non-destructive, and give almost
just as much good information as doing a solderability test.
Regards,
George
George M. Wenger
Failure Signature & Characterization Lab LLC
609 Cokesbury Road, High Bridge, NJ 08829
(908) 638-8771 Home (732) 309-8964 Mobile
E-mail [log in to unmask]
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Wednesday, July 09, 2014 1:30 PM
To: [log in to unmask]
Subject: Re: [TN] HASL Plated PCB Matter
Hi Ricardo,
I finally have your pictures posted. Sorry it took me so long, I can
usually post things much sooner than this, but I was tied-up all day
with jury duty yesterday, and when I came into work today it's been
hectic.
So here are your photos:
http://stevezeva.homestead.com/HASL1.jpg
http://stevezeva.homestead.com/HASL2.jpg
To me, this looks pretty typical of the HASL that I see, you don't ever
get perfectly flat pads with HASL.
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ricardo
Moncaglieri
Sent: Tuesday, July 8, 2014 10:16 AM
To: [log in to unmask]
Subject: [TN] HASL Plated PCB Matter
Dear Colleagues,
I´m working in the aerospace industry at INVAP SE - ARGENTINA and my
rol is QA Electronic Service Manager.
Would like to know your comments on following matter:
Have requested to a new PCB provider some HASL plated pcb specimens in
order to verify its quality and found out what enclosed pictures show:
100% of plated pads have its plating drained or slided off toward the
same direction from left to right affecting coplanarity.
As per our visual inspection at first conclusion we stated that it is
an Indicator Process (not necessary dewetting related issue) and could
be caused between others, from:
1) Pb % degraded.
2) Low air flow temperature trend.
3) Angle of impact of air flow.
We asked the provider to define cause of this issue. We didnt do a
metallographic analisys to verify Cu6Sn5 presence to confirm
intermetallic fusion.
We run the J-STD-003 test "C" to verify solderability and it is 100% Ok
well wetted, furthermore we soldered a desoldering ribbon (previously
tin plated) directly to a pad without using of Flux nor solder and
verified that its adherence is very good which indicates pad surface
would be well plated.
As per your experience: Do you agree with us on our conclusions
specially that it seems to be not a strictly dewetting matter?
Appreciate too much your feedback on such a matter.
Brgds, Ricardo Moncaglieri
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud
service.
For more information please contact helpdesk at x2960 or
[log in to unmask]
______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud
service.
For more information please contact helpdesk at x2960 or
[log in to unmask]
______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud
service.
For more information please contact helpdesk at x2960 or
[log in to unmask]
______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
