lee,
Can you provide us the paper you have mentioned in your mail for the barrel to copper.
Please provide me your mail id so that i can correspond with you on this further.
Thanks in advance for your reply.
Regards
suresh
Dehoyos, Ramon wrote at Thu Apr 12 18:04:28 GMT+05:30 2007:
>
> Lee:
> Good to know info. ^ current density, ^ brittleness, v plating
>uniformity and density. Good things take time.
> Thanks,
> Ramon
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee parker
>Sent: Wednesday, April 11, 2007 12:42 PM
>To: [log in to unmask]
>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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--
Thanks in advance for your reply.
Regards
T.Suresh Babu
Asst.Manager-Development.
Plot No.16,Jigani Indl Area,
Anekal Taluk
Micropack Ltd.,
Bangalore 562106
Ph-091-80-27825223/27826422
Fax:091-80-27825225
Email: [log in to unmask]
-------------------------------
Micropack Ltd, Bangalore, India
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