Hi Mr. Parker:
Could you please give me direction how I can get your paper you presented at APEX.
Regards
----- Original Message ----
From: Lee parker <[log in to unmask]>
To: [log in to unmask]
Sent: Wednesday, April 11, 2007 12:41:40 PM
Subject: Re: [TN] Via hole plating corner crack
Victor
You mentioned that the current density is 30 amps per square foot. I
consider this to be extremely high and not only will cause brittle copper,
but highly non-uniform copper in the barrel. I presented a paper at Apex
that mathematically modeled the copper uniformity in the barrel to the
plating parameters including current density, you might want to review this
paper. The model shows there is an inverse linear dependence between the
copper uniformity and the plating density.
Best regards
Lee
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: "Victor G. Hernandez" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, April 10, 2007 10:36 AM
Subject: Re: [TN] Via hole plating corner crack
Can you please post the crack via cross section photo for viewing, "a
picture is worth one thousands words". Is this SnPb or LF?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of C J Long
Sent: Tuesday, April 10, 2007 9:20 AM
To: [log in to unmask]
Subject: [TN] Via hole plating corner crack
Dear Techneter:
I recently experienced customer return of corner crack. The PCB is 50
mil
thick, 10 mil via, OSP finish and corner crack is over the 4 corners of
top
and bottom
of hole. Crack is started from the bottom of external foil and crack
through
the entire plating. You can see the photo (file: crack through) of
actual
failure. Plating is unusual column type crystal on the surface. In the
hole
barrel, the plating crystal is regular. We also performed many in-procss
WIP
cross section (refer to the file "crack 9X IR") and we could only find
the
crack after 6X IR reflow and its crack is started from external foil top
corner. I have sucessfuly duplicated similar failire with very high
plating
current density of 30ASF with very low brighter (0.15cc/l), but its
failure
mode is crack on ehe top of external foil not the same as customer
return.
My questions are:
1. Are these two failre modes with the same root cause? What is the
reason
one crack is started from the foil top corner and the other is from the
bottom?
2.Is there any non-destructive method able screening the cracked
plating?
http://tw.pg.photos.yahoo.com/ph/minalong2003/album?.dir=/5c32scd
Thank you very much.
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