Thanks to all respondents--good tips. I wasn't aware of the leader part
issue: Very impressive they can meet exactly the same visuals.

I also look forward to looking over what Richard posts tomorrow (as always
with posts from Richard!)

Wayne Thayer

On Wed, Feb 9, 2022 at 2:55 PM Yuan-chia Joyce Koo <[log in to unmask]> wrote:

> x-ray is good tool to see if different location using different size
> of chip (chip shrink) or not - you might have different working temp
> range due to MFG process limitation.  Way back, one of the vendor
> provide chips at reduced temp range (different bin) for far east
> commercial usage, but main location process version got wider temp
> range and narrower parameters.  I order specified for main location
> only with 6month early notification with possible "last time batch
> buying" if MFG location change (pay extra for the clause).
> - I was told un- officially, the difference due to less MFG of
> environment control (water, cleanroom, etc) and eliminate burn in
> steps with off shore location.
> that is beside the counterfeit.  good luck.
> jk
> On Feb 9, 2022, at 1:44 PM, Wayne Thayer wrote:
>
> > Greetings-
> >
> > The only way I've been able to keep parts moving in this
> > environment of
> > part shortages and 72 week lead times is by constantly finding
> > substitutes.
> >
> > The least appetizing substitute option is offshore brokers. We are
> > revising
> > our counterfeit detection strategy for minimizing cost/benefit (and
> > time).
> > My inclination is to do careful visual inspections, especially
> > labels and
> > lead finish, followed by solvent testing and a simulated Pb-free
> > soldering
> > profile on samples of the lot. I also compare the decapsulated die
> > faces
> > with known genuine parts.
> >
> > Is anybody else working this issue? Our old corporate document
> > suggests XRF
> > and x-ray inspection, but I'm not seeing the value in those. XRF is
> > a great
> > way to see if your system is Pb-free, but I'm more interested in
> > whether
> > the leads were soldered to previously which a thorough visual
> > inspection
> > should find.
> >
> > Thanks,
> >
> > Wayne Thayer
>
>