Don,
You are indeed correct in stating that the material properties have only a little to do with delamination.
A material with a high Tg and Td simply means that the materials themselves will stand up a little better in higher Pb-free reflow temperatures. The suppliers of the prepreg still need to do a good job of lamination, or it does not really matter if the materials themselves have better capabilities. Some very good postings on this subject from Susan Mansilla and Werner Engelmaier, amongst others, were posted here within the last two months.
The N4000-6 and -13 have been delaminating at several of my clients at NORMAL (read 210-235 C.) reflow temperatures, and in addition have proven to have very poor pad retention. I do not know enough about board fabrication to determine why that is, I can only report what I see happening. It has not been isolated to a single board fabricator or prepreg supplier.
In addition, during normal BGA rework, the pads without trace attachments literally slide off of the boards when the BGA is removed. We could not do anything to the process to prevent it.
These boards were baked to remove moisture. Did not make any difference, they still delaminated when passed through the reflow at 200 deg. C.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Donald Kyle
Sent: Wednesday, March 01, 2006 7:47 AM
To: [log in to unmask]
Subject: Re: [TN] High-frequency losses (e.g., SATA)
All;
Sounds like N4000-6 and N4000-13 are not suitable for a LF assembly processes. Is that what I am hearing?
According to Nelco's web site, the N4000-13* materials are LF assembly compatible.
Their Tg is 210C. The N4000-6 is not LF compatible and has a Tg of 175C.
There's more of course to it than just the Tg.
I have seen delamination problems with N4000-6 as well as N4000-13.
According to Nelco, the N4000-12* materials are LF assembly compatible as well. The Tg for this material is 190C.
Has anyone tested N4000-12 with a LF process and then temperature cycled it?
Donald
At 04:32 PM 2/28/2006, you wrote:
>John,
>
>Do you have fact about it?
>
>I'm asking because I'm working on a design which has 3.125 GHz signals
>on it and I'm looking for Nelco 4000-13.
>
>If I can avoid problem of delamination during the lead free assembly
>process and get rid of another simulation pass and rework because of
>change in material, it will be appreciated.
>
>
>Louis Guérin, C.I.D.+
>
>Conception de Plaquette de Circuit Imprimé| PCB Designer
>
>Lyrtech RD inc.
>( Téléphone - International/Phone - Worldwide: 1 (418) 877-4644 # 242
>( Sans frais - Canada et É.-U./Toll-free - Canada and USA: 1 (888)
>922-4644 # 242
>1 Téléc./Fax: 1 (418) 877-7710
>
> Infinite possibilities...TM
>
>
>-----Message d'origine-----
>De : TechNet [mailto:[log in to unmask]] De la part de John Burke Envoyé :
>28 février 2006 14:01 À : [log in to unmask] Objet : Re: [TN]
>High-frequency losses (e.g., SATA)
>
>Agreed,
>
>One thing though, if you are using lead free soldering temperatures
>Nelco - 12 works fine, Nelco - 13 does not work at all.
>
>John
>
>John Burke
>Senior Manager - Operations , Optichron [log in to unmask]
>W: 510 249 5233
>M: 408 515 4992
>http://www.optichron.com
>Profile: https://www.linkedin.com/e/fps/2665502/
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Dwight Mattix
>Sent: Tuesday, February 28, 2006 10:09 AM
>To: [log in to unmask]
>Subject: Re: [TN] High-frequency losses (e.g., SATA)
>
>Have a look at FR408. It's more like N4000-12 electrically. However,
>both
>FR408 and -12 have been close enough to -13 electrical performance to
>drop in as replacements in our sub-2GHz applications. Both FR408 and
>-12 have similar innerlaminar bond strength as N4000-6. That is nearly
>double the inner laminar bond strength of -13. Equally important in
>multi-lam single ply uVia build up constructions has been -12 and
>FR408's (apparently) lower delam sensitivity to retained moisture. -13
>is not very hydroscopic but it will separate from it's glass sooner
>than 408, -6 or -12 if there is retained moisture.
>
>We've used a ton of -13 over the years and still use it in selected
>applications for it's higher Tg and marginally lower loss but if it's
>single ply and sequential lam FR408 or -12 are the way to go.
>
>my $.02,
>dw
>
>At 10:21 PM 2/27/2006, Ofer Cohen wrote:
> >In similar occasion of similar frequency (3.125GB/s) we've declined
> >IS410 and other, and approved IS620 and Nelco 4000-13. We are
> >checking no Nelco 4000-12 which is supposed to be electrically
> >equivalent to the
> >-13 but chipper and LF compliant.
> >
> >Regards
> >Ofer Cohen
> >Manager - Quality Assurance and Reliability SIEMENS COM FN A SB
> >
> >-----Original Message-----
> >From: TechNet [mailto:[log in to unmask]] On Behalf Of Michael Dunn
> >Sent: Monday, February 27, 2006 22:40
> >To: [log in to unmask]
> >Subject: [TN] High-frequency losses (e.g., SATA)
> >
> >Hello from a new member.
> >
> >We're wanting to run 1.5Gbps (differential) SATA signals over a
> >backplane, and naturally have SI concerns. The distance will be up
> >to 15". We're considering IS410 and IS620 (620 has about 2.5x less loss).
> >
> >I've tried using calculators from Rogers and Isola, but for some
>reason,
> >they only report losses in single-ended lines.
> >
> >Can anyone share experiences, or suggest other tools that may be of
>use?
> >
> >
> >Thanks!!!
> >
> >
> >
> >Michael Dunn
> >Sr. Hardware Engineer
> >Kaleidescape Canada Inc.
> >611 Kumpf Drive, Unit 100
> >Waterloo, ON N2V 1K8
> >Canada
> >Ph: 519-772-6427
> >Fx: 519-772-6401
> >
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