Hi Dennis, Dewey, G, W, IPC LF Listservers
<Because moving towards higher Tg increases the costs of the PCBs, where
<ever possible I would have liked to not change the laminate.
As I have wrote before, this is possible yet you have to know your entire
product which includes processing, usage, servicability, reliability.
<Having different spec PCBs would also cause confusion with our purchasing
<& IQA departments and/or our customers (who supply the PCB specs). Some
<may not be aware of the implications of higher processing temperatures and
<rely on us to provide this expertise.
Absolutely I agree. You are the OEM, You are the GOD, customer, and can not
delegate that to a subordinate. Some do to First Tier EMS suppliers yet
they do themselves and their customers a great disservice.
<Therefore if there was a general rule, which perhaps could be "up to
<6layers, FR4 Tg140C is sufficient, all else use Tg170C or greater", it
<provides a good guideline, and would ultimately help us and our
<customers ensure a reliable product.
ANYONE who suggests to you without knowing your product, materials,
components, life expectancy i.e. "materials, methods, men, management,
more" would be WRONG and you will pay in "end games"
You have to find out for your current product how close you are now to the
limits of what you are guaranteeing to your customers. Hire a Reliability
Engineer, or a Good Product Engineer and set them free.
BTW our buddy Honeywell-Dewey gave a good answer, I knew we could could on
him for more than humour.
Yours in Engineering, Dave
Y i Engr, MA/NY DDave
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