Lee,
Thanks again. No questions and no disagreement with Navier Stokes at all.
Didn't mean to imply so if that's how you took the response. Sorry.
Roger
----- Original Message -----
From: "Lee parker" <[log in to unmask]>
To: "EIMCNews" <[log in to unmask]>; <[log in to unmask]>
Sent: Wednesday, July 25, 2007 8:33 AM
Subject: Re: [TN] Question on plated through holes general
> Roger
>
> My paper made no assumptions about current density variation in the PTH.
>
> You are correct "linear" is correct
>
> My paper was presented at the IPC APEX meeting in LA this spring
>
> I suggest you get out your text book on fluid mechanics. The Navier Stokes
> equations are the most basic equations describing fluid flow whether it is
> grease in a bearing or the hypersonic flow around a reentry nose cone. I
> have used these relationships for studies in both areas. The flow rate in
> a PTH is dependent upon the entrance velocity, (or pressure gradient) the
> diameter of the hole, the length of the hole, the viscosity and density of
> the fluid. See Schlichting's book chapter 5.
>
> I also suggest you obtain a copy of my paper and if you still have
> questions give me call.
>
> Best regards
>
> Lee
>
>
> ----- Original Message -----
> From: "EIMCNews" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, July 25, 2007 2:28 AM
> Subject: Re: [TN] Question on plated through holes general
>
>
>> Lee,
>>
>> Werner is not incorrect but the percentage difference in current density
>> from the board surface to the center of the hole is relatively small.
>> Center-of-hole current density was extensively measured by several
>> electrochemical scientists working for those manufacturers trying to
>> fabricate outrageously thick boards for supercomputers in the 1980's.
>> What
>> I should have said is that the small current density difference from
>> surface
>> to hole does not account for the huge differences in plated copper
>> thickness. Differences in board design can of course vary but it's been
>> proven that if you get better through-hole solution movement you will
>> come
>> close to achieving 1:1
>>
>> I'm not sure what you mean in referring to your Apex paper and linier
>> relationship. You meant linear, right? Current density relationship to
>> thickness was better understood when Richard O. Hull made his simple Hull
>> Cell invention. I'm not disputing your Navier Stokes equations but
>> getting
>> the solution to flow through the hole is the key. It is not easy.
>> Solution
>> impingement has been mentioned but it is generally not successful because
>> it's not possible to get the same amount of solution flow in each hole of
>> a
>> circuit board, especially if that board has as many as 20,000 holes.
>>
>> Not only that, the composition and function of the diffusion layer varies
>> so
>> greatly from the planar surface of the board to individual holes that
>> it's
>> not just the copper ions that are inconsistently depleted in the holes
>> but
>> the organic additives as well. Plating circuit boards spawned a whole
>> generation of brighteners that supposedly aided throwing power. All they
>> really did was improve the color and physical appearance of deposits
>> without
>> improving plating thickness distribution.
>>
>> Reducing overall current density to less than 8 a.s.f. or less (I've seen
>> it
>> done and so probably have you) does nothing but give the solution
>> movement
>> in the holes more time to equalize to that on the surface. Plating at
>> low
>> CDs also equalizes the differences overall on the board but that's a
>> subject
>> for another day. Copper electrolytes are much healthier when they're
>> operated at far higher current densities than are common today. Another
>> subject for another day. True to form, plating discussions on TechNet
>> are
>> relatively infrequent but they can garner lots of disagreement.
>>
>> Sincerely,
>>
>> Roger Mouton
>>
>> EIMC - Advanced Plating Technologies
>> (949) 481-5194
>> www.smartcatshield.com
>> [log in to unmask]
>>
>>
>> Notice of Confidentiality
>> The information contained in and transmitted with this email may be
>> confidential and is intended only for the individual or entity named
>> above.
>> If you are not the intended recipient, you are hereby notified that
>> inadvertent disclosure of this information to you does not constitute a
>> waiver of confidentiality privilege and that any review, disclosure,
>> copying, or use of the contents of the email by you is prohibited.
>>
>> ----- Original Message -----
>> From: "Lee parker" <[log in to unmask]>
>> To: "EIMCNews" <[log in to unmask]>; <[log in to unmask]>
>> Sent: Tuesday, July 24, 2007 10:22 AM
>> Subject: Re: [TN] Question on plated through holes general
>>
>>
>> > Roger
>> >
>> > Werner is correct.
>> >
>> > The paper I presented at Apex found a linier relationship between the
>> > current density and the cooper distribution in the hole which is often
>> > refered to as dog boning. My model combined the well known Navier
>> > Stokes
>> > equations for viscous flow and Faraday's law for electroplating. As the
>> > plating solution passes through the hole the copper ion concentration
>> > in
>> > the solution is diminished and consequently, the plating rate is
>> > reduced.
>> >
>> > I have been in the PCB business for over 30 years and was located in
>> > the
>> > AT&T shop in Richmond as part of Bell Laboratories staff. This was one
>> > of
>> > the largest shops in the world. We constantly saw the empirical
>> > evidence
>> > of this relationship. My paper confirmed the existence of the
>> > relationship
>> > using a first principals mathematical analysis.
>> >
>> > Best regards
>> >
>> > Lee
>> >
>> > J. Lee Parker, Ph.D.
>> > JLP Consultants LLC
>> > 804 779 3389
>> >
>> >
>> > ----- Original Message -----
>> > From: "EIMCNews" <[log in to unmask]>
>> > To: <[log in to unmask]>
>> > Sent: Tuesday, July 24, 2007 12:55 PM
>> > Subject: Re: [TN] Question on plated through holes general
>> >
>> >
>> >> There seems to be a continuing misunderstanding of the forces at work
>> >> in
>> >> plating through holes. First, you're reporting fairly thick copper at
>> >> the
>> >> knee of the hole. The assumption is that the thickness diminishes
>> >> toward
>> >> the center of the hole. If the hole is cross-sectioned do you find
>> >> this
>> >> to
>> >> be the case? If so, this is normal but not really desirable.
>> >>
>> >> There's more expansion at the knee of the hole (Werner can you weigh
>> >> in
>> >> on
>> >> this too please?). If the physical properties of the deposit are poor
>> >> then
>> >> there's the likelihood of cracks at the knee.
>> >>
>> >> As for plating thick boards at low current density, the only reason
>> >> for
>> >> doing this is that there's additional time for the electrolyte to
>> >> better
>> >> circulate through the barrel of the hole. Contrary to some popular
>> >> beliefs,
>> >> the holes of circuit boards are NOT low current density areas. The
>> >> thickness of the deposit in the hole is less than on the surface of
>> >> the
>> >> board because the hole doesn't see the same circulation of fresh
>> >> electrolyte
>> >> as the surface. Ogden and Tench proved this over 20+ years ago.
>> >> Numerous
>> >> attempts have been made over the years to improve plating solution
>> >> circulation through the hole. It becomes more difficult with thick
>> >> boards
>> >> and/or smaller holes.
>> >>
>> >> Sincerely,
>> >>
>> >> Roger Mouton
>> >>
>> >> EIMC - Advanced Plating Technologies
>> >> 949 481-5194
>> >> www.smartcatshield.com
>> >> [log in to unmask]
>> >>
>> >>
>> >> Notice of Confidentiality
>> >> The information contained in and transmitted with this email may be
>> >> confidential and is intended only for the individual or entity named
>> >> above.
>> >> If you are not the intended recipient, you are hereby notified that
>> >> inadvertent disclosure of this information to you does not constitute
>> >> a
>> >> waiver of confidentiality privilege and that any review, disclosure,
>> >> copying, or use of the contents of the email by you is prohibited.
>> >>
>> >> ----- Original Message -----
>> >> From: "Lee parker" <[log in to unmask]>
>> >> To: <[log in to unmask]>
>> >> Sent: Tuesday, July 24, 2007 5:49 AM
>> >> Subject: Re: [TN] Question on plated through holes general
>> >>
>> >>
>> >> > Ralph
>> >> >
>> >> > I presented a paper at IPC this spring on the variables which affect
>> >> > the
>> >> > copper uniformity in PTHs. You can probably get a copy by contacting
>> >> > Tom
>> >> > Newton at IPC.
>> >> >
>> >> > It is difficult for me to imagine a greater copper thickness causing
>> >> > the
>> >> > barrel to become more susceptible to cracks. The thicker the copper
>> >> > the
>> >> > lower the stress for a given load and consequently the lower the
>> >> > strain.
>> >> > What may be going on is the uniformity of the copper which causes
>> >> > stress
>> >> > concentrations and the ductility of the plated copper. As I
>> >> > mathematically
>> >> > demonstrated in my paper, the current density used in plating has a
>> >> > strong
>> >> > impact on these parameters. The thicker the board the greater the
>> >> > need
>> >> > for
>> >> > low current density.
>> >> >
>> >> > I would ask the supplier to measure the ductility of the plated
>> >> > copper
>> >> > for
>> >> > several current densities and draw your own conclusions.
>> >> >
>> >> > Best regards
>> >> >
>> >> > Lee
>> >> >
>> >> > J. Lee Parker, Ph.D.
>> >> > JLP Consultants LLC
>> >> > 804 779 3389
>> >> >
>> >> >
>> >> > ----- Original Message -----
>> >> > From: <[log in to unmask]>
>> >> > To: <[log in to unmask]>; <[log in to unmask]>
>> >> > Sent: Tuesday, July 24, 2007 9:00 AM
>> >> > Subject: RE: [TN] Question on plated through holes general
>> >> >
>> >> >
>> >> > Lee,
>> >> >
>> >> > Do you also have any inromation about max Cu thickness in the PTH?
>> >> > In
>> >> > the recent past we had some cracks and the min was ok but the max
>> >> > showed
>> >> > values aroung .045mm. Our supplier said that the crack was caused
>> >> > due
>> >> > to
>> >> > too thick copper. The crack location was on the top just below the
>> >> > Cu
>> >> > ring.
>> >> > Do you or anybody else has a suggestion how to handle or specify
>> >> > this?
>> >> >
>> >> > Regards
>> >> > Ralph
>> >> >
>> >> > -----Original Message-----
>> >> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee parker
>> >> > Sent: Friday, July 20, 2007 10:42 PM
>> >> > To: [log in to unmask]
>> >> > Subject: Re: [TN] Question on plated through holes general
>> >> >
>> >> > David
>> >> >
>> >> > I always advise one mil or more in the PTH. Given the non-uniformity
>> >> > often seen in the PTH I would also spec the drill quality and the
>> >> > ratio
>> >> > of the copper at the top of the hole and in the center.
>> >> >
>> >> > Best regards
>> >> >
>> >> > Lee
>> >> >
>> >> > J. Lee Parker, Ph.D.
>> >> > JLP Consultants LLC
>> >> > 804 779 3389
>> >> >
>> >> >
>> >> > ----- Original Message -----
>> >> > From: "David Harman" <[log in to unmask]>
>> >> > To: <[log in to unmask]>
>> >> > Sent: Friday, July 20, 2007 4:23 PM
>> >> > Subject: [TN] Question on plated through holes general
>> >> >
>> >> >
>> >> > I have a quick question and our standard that we have maybe an older
>> >> > one. We currently use the ANSI/IPC-A-600 Rev E
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > Page 70 Micro section:
>> >> >
>> >> >
>> >> >
>> >> > There is a table describing copper plating thickness min,
>> >> > requirements
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > Class 1
>> >> > Class 2 Class 3
>> >> >
>> >> > Average Min Thickness .020mm (0.0008in) 0.025mm
>> >> > (0.001 in) 0.025 mm (0.001 in)
>> >> >
>> >> >
>> >> >
>> >> > Minimum this area .0015 mm( .0006 in)
>> >> > 0.020
>> >> > mm
>> >> > (.0008 in) 0.020mm (.0008 in)
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > Can anyone tell me if this still is a current standards for copper
>> >> > plating thickness measurements.
>> >> >
>> >> >
>> >> >
>> >> > David Harman
>> >> >
>> >> >
>> >> >
>> >> >
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