Valerie,
my ignorance doesn't let me full understand what you are saying.
Would you please explain to me the meaning of DMA, DSC and TMA test
methods?
THX, Ivan
P.S. I value your comments. :-)
Il giorno 04/nov/05, alle ore 22:10, Valerie St.Cyr ha scritto:
> for what it's worth, I have added my thoughts on the subject after
> Dewey's
> (see below)
>
>
>
>
>
> "Whittaker, Dewey (AZ75)" <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]
>
> To: [log in to unmask]
> cc:
> Subject: Re: [TN] board material for high temp
> James and others,
> You have had some good responses, but as Richard said when he
> quoted Sir
> Doug,"It depends", is still the best answer. It depends on the layer
> count, smallest PTH, smallest via, aspect ratio, thermal management of
> your design, number of reflow processes prior to ship, max reflow
> temperature[eutectic vs. RoHS compliant( Lead-Free)], time above
> liquidness, need to support rework, life cycle (1-3 years; 5-7 years;
> 20+ years) and end use environment.
>
> As it stands right now, going up the scale in a slash sheet sort of
> way,
> you have the following:IPC-4101/21, /24, /26, /121, /124, /101, /99,
> and my personnel favorite /126.
>
> The attributes that are key are as follows:
> * Tg - I favor minimum 170 C, others agree a minimum 150 C is
> adequate.
>>>> As your layercount and thickness increase you should be
> looking at 170C. This is a "tricky" requirement, in that if
> you do not specify the test method, you will never really
> know what you have ... I favor 170C by TMA; which should be
> about 180C by DSC and 200C or better by DMA.
>
> * Moisture - 0.5% or less
>>>> This will be critical at these temperatures!
>
> * Thermal Resistance
> T260 - 30 minutes minimum
> T288 - 5 minutes minimum( some believe 2 minutes is sufficient)
>>>> I'm not sure that 2 minutes is sufficient; 5 should be
> achievable; should be the minimum
>
> T300 - AABUS( as agreed between user and supplier)
>
> * Decomposition Temperature - I would like 350 C ( 5% wt. loss)
> general
> consensus 330 C minimum
>>>> Like T288, as your design complexity increases, you need better
> decomp temps. Also, you should see the plots. You want to know
> the 2% wt. loss temp and 5% wt. loss. I don't know what the
> temp should be for 2%, but for 5% I also like 350 (maybe 340, but
> not 330 - unless you have a not too demanding application)
>
>
> * Z Axis CTE - I want 3% or less, general consensus 3.5% maximum
>>>> less is better; they should all be able to be 3% or less
>
> * CAF Resistance - AABUS
>>>> this is really hard to specify!
>
> * Curing Agent - Although this is a dicy subject, I'll mention it
> anyway. Phenolic cure systems presently outperform traditional FR4
> formulations as it pertains to maintaining functionality while being
> exposed to a greater number of higher thermal excursions.
>>>> This isn't a "functional" specification, but rather an indication
> based on current thinking: non-dicy laminates are doing very well for
> lead-free assembly conditions; but does that mean that dicy laminates
> will never be able to be lead-free? not true - depends on your
> application.
>
>>>> Unfortunately, with "lead-free assembly" processing, life just
> got a whole lot harder. For awhile, anyway, it will be difficult to
> know what is going to be OK, or not, without specific trials on
> specific designs manufacturered by specific fabricators and run on
> specific assembly lines - we simply have not tested all combinations
> and permutations as yet ... and process control at assembly will also
> take on even more importance. <<<
>
>
> The Rev B of IPC-4101 will include additional rhetoric, as well as the
> new slash sheets, to help you make an informed choice as it
> pertains to
> laminate selection, but it can not do it alone. IPC-6012, IPC-2221,
> IPC-600 and the Via Protection Task Group will also have to be revised
> for them to be an effective reference source to deal with all the new
> performance requirements of today's Market Place. I will, with
> others be
> working to make that happen.
> Chairman of IPC-4101
> Wannebee Poet Laureate of Tech-net
> Dewey
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of James TerVeen
> Sent: Wednesday, November 02, 2005 12:14 PM
> To: [log in to unmask]
> Subject: [TN] board material for high temp
>
> What does everyone us for board material for High temperature solder
> applications. We have a new product that will require the use of
> high
> temperature solder. Will the use of conventional FR4 be sufficient.
>
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