Pradeep,
you'll get into deep problems! Are you sure it's really 13,000 revolutions
per MINUTE? And the board is not circular but rectangular. 13,000 rpm,
that's the max for a Laverda racer bike. Imagine the littlest unbalance in
such a machine, and there will be a catastroph. You have to consider:
1. The starting acceleration of that thing. If the start is too violent, you
can get an acceleration force that will make the componensts fly off.
2. How do you make a perfect balance of a PWB? By counterweights or trimming
by drilling holes etc ?
3. Even a very, very small wobbling will make the hole thing crash.
4. What kind of bearings? These may cause additional vibrations that can
destroy sensitive components.
5. What kind of components are you going to use? Check if there are
mechanical data available for each of them.
6. How do you dare give life expectancy (if this thing has to work for a
long time.
7. There may be standing wave nodes between the mounting points. Not healthy
for microvias and solder joints.
Without knowing what strange design you are working with, I'd suggest a
circular LTCC with all resistors and caps and maybe even inductors
integrated in the ceramic. And make a symmetrical design. The balance must
be as perfect as possible.
Finally, when you test your product, see that you are not near it, because
at that speed you have a dangerous thing in front of you. Your speed is not
far from a spinning CD-ROM. Such a disk is very close to perfection in a
balance point of view, nevertheless, things can happen. Some guys tested
what happens with a CD, if you double the rotational speed, and you can see
yourself below.
http://www.qedata.se/e_js_n-cdrom.htm#inledning
Good Luck and take care
Inge
----- Original Message -----
From: "Pradeep Menon" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, December 15, 2009 2:05 AM
Subject: [TN] Tensile strrength
> We have one of our customers who will be mounting a 6 layer PCB of size
> 110x45mm on a shaft which will be rotating at 13000 rpm. The pcb is
> mounted on a supporting plate with 3 -6 mounting points. He wanted our
> suggestion on whether he can use normal FR4 or he should be going with a
> metal core PCB. The board is 1.6mm thick.
>
> We felt that FR4 might be sufficient and the bond strength of the
> components mounted on the board will be more critical than the PCB tensile
> strength. We felt since thermal management is not an issue in this case,
> metal core may not be required. Will tensile strength of the board be a
> critical parameter in this case and if so, any inputs on what can be
> suggested. Any other suggestions for this application.
>
> Rgds
>
> Pradeep
>
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