> - Bargain-price/cheapie/fallout zeners diodes are basically units that
> fail to pass the manufacturer's final test. I was given a box of them
> which was marked "semiconductor scrap". Some were usuable. Some were
> not. None were first class.
<snip>
> quality semiconductors.
>
<snip>
::I wonder: What is the difference in "quality" between fallout and
first-class, in Zeners? Having fabricated a lot of these (starting with
undoped silicon), the "fallout" in manufacturing is usually -- oops! missed
the target avalanche voltage! -- or -- oops! failed to meet another
parameter such as leakage current below avalanche, or dynamic impedance
(slope of Vz/Iz). Missing a parameter didn't mean the devices were lesser
quality in any way, just missed a JEDEC (EIA) or military specification,
many of which are arbitrary to begin with. "Quality" rejects, resulting
from bad diffusion lots, are normally destroyed prior to lead attachment
(dice are probed at the wafer or die level) and would never find their way
into anyone's inventory, surplus or otherwise.
-WB2WIK/6
> cheers, Ian
>
> - R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
> www.vcnet.com/measures.
> end
>
>
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