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July 2002

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Subject:
From:
Earl Moon <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 2 Jul 2002 12:54:51 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (222 lines)
Ingemar,

As a former aircraft navigator, before becoming a pilot, I think I coined
the term terrorist before current models were invented. Used to use a
sextant to shoot sun lines and star fixes. Real Magellan but terrorized many
of my crew members when, only occasionally, straying just a bit off course
mostly when following the wrong star. Nothing changed for me in these times
but some stars still shine brighter than others. Whether they'll offer the
correct course is another matter. You're certainly right when addressing DFM
in such a way.

Earl

----- Original Message -----
From: "Ingemar Hernefjord (EMW)" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, July 02, 2002 5:13 AM
Subject: Re: [TN] FAULT/DEFECT TEST STRATEGY


> So, so, don't weep dear Peter,
> next line may comfort you a little
> Production engineers are not included, what we mean are Design
Engineers...woe, woe...now I'll get that beeswarm on myself instead...
> Like your humoristic spirit, Peter...
>
> Severily: DFM is like star of Betlehem, we too try to walk steadily in
that direction.Unfortunately, some young Design Engineers don't take DFM
seriously.
>
> Ingemar
>
>
>
>
> -----Original Message-----
> From: [log in to unmask] [mailto:[log in to unmask]]
> Sent: den 2 juli 2002 10:11
> To: TechNet E-Mail Forum.; Ingemar Hernefjord (EMW)
> Cc: [log in to unmask]
> Subject: Re: [TN] FAULT/DEFECT TEST STRATEGY
>
>
>
> Dear Ingemar,
>
> I am deeply hurt! (sulk!) What's wrong with us Production Engineers, eh?
We
> have to make all this hardware so that it works, and it's important that
we
> have an input to board design. Maybe you're actually a wee Viking devil,
> sitting on Earl's left shoulder, tempting him away from the true path of
> DFM!?
>
> Peter
>
>
>
> "Ingemar Hernefjord (EMW)" <[log in to unmask]>
> 02/07/2002 02:49 PM
> Sent by: TechNet <[log in to unmask]>
>
> Please respond to "TechNet E-Mail Forum."; Please respond to "Ingemar
> Hernefjord (EMW)"
>
>               To:  [log in to unmask]
>               cc:  (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
>               Subject: Re: [TN] FAULT/DEFECT TEST STRATEGY
>
>
>
>
>
>
>
>
> Hi Earl,
> you seem to cover most in those few lines
> I would add this first thing I did: use only highly skilled operators
> (unless you see 'capabilities' below as human resources). Best guarantee,
> better than good engineers....gosh...I'll be in bad situation now...
> Best regards
> Ingemar Hernefjord
> PS. unwritten rule here : never let in an engineer in the production! Bit
> of black humour, but with great deal of truth.
>
> -----Original Message-----
> From: Earl Moon [mailto:[log in to unmask]]
> Sent: den 1 juli 2002 19:14
> To: [log in to unmask]
> Subject: [TN] FAULT/DEFECT TEST STRATEGY
>
>
> Folks,
>
> I am not a test engineer but having to do catch up quickly to develop a
> sensible test strategy to find faults and/or defects usin a combination of
> test disciplines and elements. Watched my board designer spend a very long
> time placing 1800 test points, some not on grid, as something of an
> experiment on a non-HDI, but approaching it, and didn't like the results.
>
> I'm hoping some of you can offer positive, or negative, criticism
> concerning
> the following summary I've come up with though probably not new to you
all:
>
> SUMMARY
> When considering a new, fairly complex, high density PCB design (defined
> often on the basis of how many and what pitch area array devices are
> required) with limited test probe access for ICT, the following
> considerations should be met:
> 1) Ensure only highly qualified board fabrication capabilities are used.
> This must be done to provide printed circuitry that has the highest
> laminate
> integrity, hole quality and reliability, plated or coated surfaces that
> solder wet, and the ability to do adequate bare board testing in
> conjunction
> with effective X-Sectional analysis. This will prevent many other defects
> during the assembly operation as poor quality solder joints, and shorts or
> opens when hole walls fail.
> 2) Ensure only highly qualified assembly capabilities are used. This must
> be
> done to provide defect free assemblies with high quality and reliability
> solder joints, specified component placement and orientation, and the
> ability to prove all this with a well thought out test strategy.
> 3) Ensure a well thought out test strategy is in place consisting of some
> or
> all the following:
> ?
> X-Ray used on all area array devices to ensure high quality solder joints
> and the ability to reduce the number of test probe pins and test points
> relating to these device types.
> ?
> AOI capabilities to determine solder joint quality for leaded and discrete
> SMD?s as well as specified component types with proper orientations,
> polarity, and values. This too will minimize the number of test points
> required along with attendant bed of nails in those areas shown to meet
> specified requirements.
> ?
> The use of boundary scan in those circuit areas deemed viable for such
> testing.
> With all the above, it is possible to create and implement a test strategy
> capable of providing for all test requirements for our board types but RF.
> I
> am studying a R/F test plan.
>
>
> Earl Moon
>
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