Filters such as copper or zinc in the beam path help with “clipping”
specific wavelengths that are outside the detector’s sensitivity range.
Dropping the voltage or current doesn’t have the same effect.

On Saturday, September 7, 2019, Wayne Thayer <[log in to unmask]> wrote:

> What's the difference between a filter and just dropping the power?
>
> On Fri, Sep 6, 2019 at 12:39 PM Bev Christian <[log in to unmask]
> >
> wrote:
>
> > TechNetters,
> > Guy nailed it when he mentioned "Zn filter".  We (BlackBerry) just used
> > commercial grade Al foil and that seemed to do the trick.  With regards
> to
> > 2D/3D, I would think if your 3D machine is fast enough this shouldn't be
> a
> > problem (with filter).  Comments?
> >
> > Regards,
> > Bev
> >
> > -----Original Message-----
> > From: TechNet <[log in to unmask]> On Behalf Of Guy Ramsey
> > Sent: Friday, September 6, 2019 3:24 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] XRAY inspection of SMT
> >
> > We had a great discussion on this topic last year. In response we
> > purchased a gross of little dosimeters from Landauer, and characterized
> our
> > 3D AXI.
> > The results were truly horrifying.
> > We shared our results with the manufacturer. Characterized their new
> > machine and decided 3D AXI was not for us. We traded the machine for two
> > upgraded AOI machines.
> > Then we evaluated x-ray equipment with new knowledge. Added a zinc filter
> > and now do 2D x-ray at a safe and reasonable dose.
> >
> > On Fri, Sep 6, 2019 at 3:07 PM Wayne Thayer <[log in to unmask]>
> > wrote:
> >
> > > I thought you guys would get a kick out of something Analog Devices
> > > just sent me when asked about a voltage reference chip apparently
> > > damaged by XRAY inspection:
> > >
> > > "Given all the variables that can affect device performance, Analog
> > > Devices, Inc. does not recommend subjecting non-radiation hardened or
> > > tolerant devices to radiation exposure beyond normal background
> > radiation.
> > > "
> > >
> > >
> > > Brilliant, huh? Don't XRAY ANY ADI parts unless they are the tiny
> > > subset of the radiation hardened line!
> > >
> > > My expectation is that they would give a dosage range. Silly me....
> > >
> > > Wayne Thayer
> > >
> >
>


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Bhanu Sood
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