Actually it was from David Bergman.
Here is what I received as a follow up from Harvey Miller which is actually
more useful,
Kind regards,
John
From California Circuits letter, November 10, 2006 -----FYI-----Harvey
Miller
Lead Free is not FREE!!
Joe Grondona, President of Sprig Circuits, recently copied me on a letter
that he had sent to Chrys Shea about her article in PCD&M concerning an
issue with soldering lead free components that once were not a problem. I
have copied Joe's letter below.
"Hi Chrys,
Thank you for addressing the difficulties of ROHS soldering in the October
issue of Printed Circuit Design and Manufacture. I have been having a
difficult time with one particular customer regarding blowholes. You
describe it perfectly, boards solder fine with tin lead but blow horribly
with lead free.
We have found that traditional cross-sectioning does not expose the rough
drilling that seems to cause this problem.
Assume an 18x24 panel is in a North, South, East and West (NSEW)
orientation.
Most component holes are designed in that same orientation. Typically when
we punch a coupon we attempt to orient a row of holes so that we can inspect
a number of holes with the one sample. NSEW The glass fibers which make up
the panel are also in a NSEW so when we grind one of these x-sections all of
the fibers are aligned almost perfectly with the hole wall and plating we
are inspecting. Result: perfect cross section.
Now rotate the punch or cross section 45 degrees in relationship to the
panel or more importantly glass fibers. Northwest, Northeast, Southeast and
Southwest. This is where the rough drilling is taking place. Most board
fabricators would not believe that they could be producing hole walls that
look so bad. It appears that when the glass is not aligned with the drill,
it gouges and pulls out in chunks. This is especially so with regards to the
170 Tg, high temp phenolic resin material now being specified by so many
OEMs. All laminates gouge this way but the gouging appears to be deeper and
more severe with 170 Tg laminates.
The brightener and leveler systems in our electrolytic copper plating baths
are supposed to be able to level and fill these gouges and in fact some of
them can (for a very short time). Carbon filtration of the bath to remove
breakdown byproducts and the addition of new organic chemistry must be done
on a very frequent basis in comparison to tin lead assembly products.
I believe this is an industry-wide issue as I have cross sectioned numerous
boards from a number of other manufacturers. All have exhibited some level
of this phenomenon.
I have taken the opportunity of this letter to copy both Dennis McGuirk of
IPC and Dick Crowe of California Circuits Association.
Joe Grondona
President
Sprig Circuits, Inc.
Since Joe's note to us, we have held a teleconference and have discussed
this subject at length. If you have any suggestions, please feel free to
e-mail Joe or me at [log in to unmask] and I will make certain that Joe gets
your response. In the meantime, IPC is working to help identify the issues
as it now appears that there are others as well.
John Burke
(408) 515 4992
-----Original Message-----
From: John Burke [mailto:[log in to unmask]]
Sent: Friday, December 01, 2006 8:50 AM
To: [log in to unmask]; [log in to unmask]
Subject: RE: [TN] Solder Voids in Hole barrel after W/S
I will dig it out,
Give me a minute,
John
John Burke
(408) 515 4992
-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Friday, December 01, 2006 8:41 AM
To: [log in to unmask]; [log in to unmask]
Subject: RE: [TN] Solder Voids in Hole barrel after W/S
I MISSED THAT NOTE, CAN SOMEONE RESEND THAT INFO.
VICTOR,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: Friday, December 01, 2006 10:06 AM
To: [log in to unmask]
Subject: Re: [TN] Solder Voids in Hole barrel after W/S
See the mail by Dieter Bergman on this channel a few weeks ago. There is
a
problem with drilling on lead free laminate materials that is causing
this
issue - it is wide spread.
John
John Burke
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Fenner
Sent: Friday, December 01, 2006 12:29 AM
To: [log in to unmask]
Subject: Re: [TN] Solder Voids in Hole barrel after W/S
Assuming you have adequate top and bottom preheating the cause is almost
certainly poor PCB fabrication. You could try baking out the boards
before
soldering to see if this has an effect on the incidence/severity. This
won't
cure the problem but a change will point to the cause.
Regards
Mike Fenner
Indium Corporation
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Irving Lee
Sent: Thursday, November 30, 2006 4:31 PM
To: [log in to unmask]
Subject: [TN] Solder Voids in Hole barrel after W/S
What are the critical control factors to avoid solder voids in hole
barrel
after W/S ?
We have checked following items , but still have serious solder void
problem
.
1. Good Hole Wall Quality
2. Good solderability for component tail
3. Good HASL thickness
4. No Ionic contamination
Irving Lee
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