I attended a class at the PCB Design Conference
by Rick Hartley where this topic came up, and in
a later email he gave me this note.
(I hope he doesn't mind me broadcasting it)
Laminate to be Fiber Glass / Epoxy, Flame Retardant per IPC-4101/126, 170
Degrees C Minimum, as tested per IPC-TM-650, 2.4.24C (TMA method).
Decomposition Temperature to be 340 Degrees C minimum, as tested per
IPC-TM-650, 2.4.24.6. A T288 Delamination time of 35 minutes minimum, as
tested per IPC-TM-650, 2.4.24.1C. A maximum thickness expansion of 3% from
50 – 260 Degrees C. Prepreg materials per IPC-4101/126 shall meet these
same requirements.
Hope it helps,
Jack
On 8/27/07, Klefisch, Ted J <[log in to unmask]> wrote:
>
> Hello Designers,
>
> I work for a medical OEM. We will soon be producing RoHS-compliant
> PCBA's. I am not sure what exactly to include in the fab notes to
> specify the PCB base materials for compatibility with lead-free assembly
> temperatures.
>
> For pre-RoHS boards I have included a note on the fab drawing that
> specifies "FR4, copper-clad laminates" plus board thickness and UL
> rating requirements. Our boards are generally .062" thick and 8-layers
> or less. As far as I know, we've always used conventional FR4.
>
> What would you suggest I include in a fab drawing note to assure that
> the boards survive the higher assembly temperatures? Is it enough to
> specify decomposition temperature alone or should glass transition
> temperature also be called out? Td=330C? Tg=150C?
>
> I really appreciate your suggestions and advice.
>
> Thank you.
>
> Ted Klefisch, CID
> Covidien
> 444 McDonnell Blvd.
> Hazelwood, MO 63042
>
>
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