At 06:49 AM 6/4/2003 -0700, you wrote:
>Actually, metal shielding is not costly, but it IS custom. I normally use a
>a metal stamping shop, who can punch out and bend up quickly and cheaply.
>Just draw up what it needs to look like. If the radiation is magnetic, use
>mu-metal, otherwise use beryllium-copper. These punches are NC controlled,
>so the
>engineering costs are about $200 or less.

OTOH, a progressive die (the die set for the punch press has a number of
positions, each of which forms or punches the part partially, so that
complete finished parts fall out the end at a rate of one per strike (after
you fill the "pipeline") for a box assembly for a TV tuner shield might cost
US $25,000+, but the part cost will be so much less that it will pay for
itself quickly on a consumer product.

Is this BeCu material pre-plated, Bob?

>But the best way to reduce noise is to simply make the PCB a 4-layer board,
>with the VCC and GND connected to inner layers. This will kill 90% of all
>EM radiation

Probably cheaper too. Of course if it's not good enough, it's not really
cheaper at all. ;-)

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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