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. --------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------