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October 2000

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Subject:
From:
David Fish <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 24 Oct 2000 08:06:42 -0700
Content-Type:
text/plain
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Ron:  We have two issues with flux residues on our mixed tech boards.
1 Poor probing
2 Corrosion on probes that prevent electrical connection between the
probe and the outer barrel of the probe assembly [the part that is wire
wrapped and connected to the GenRad bus]

Our test machine operators:
• Think flux residues are a pain in the gluteus maximus.
• Change probes [from a collection of different tip types: crown,
straight point,
diamond] to hopefully select [tailor] the correct probe for the probe
location. [Documenting probe changes is a ... ]
• Dry scrub probe tips with a wire brush [a little like Techni-Tool
872M1034, but with longer rows of bristles] when a fixture begins to
act-up.
• Inspect the probe side surfaces for corrosion [corrosion turns probe
shafts black][from the flux???] that prevents good contact. [Operators
seem to change probes haphazardly. The probe manufacturer recommends a
change-out schedule ... 50k hits or something like that.]

Sounds like constant maintenance, maintenance, maintenance ... ooooo
babeeee, if maintenance wasn't tough enough to start with ...

I wonder if the cost analysts figured this in when we changed over to
NC?  Yes, some fluxes probe better than others.

Dave Fish

"Hollandsworth, Ron" wrote:

> Hello TechNet:
> I have another question???
>
> In the No-clean/Low-residue world, could you respond to this another
> question?
>
> 1.      After processing your boards with a No-clean/Low-residue paste or
> flux, and do not clean them, do you have problems at your incircuit test
> with flux build up on pogo pins?
>
> 2.      If you have problems with your pogo pins, do you
>
> A.      Clean the pogo pins and re-use them?
> B.      Replace the pogo pins?
> C.      Have found a formula/recipe/profile to process the boards w/o doing
> A or B/
>
> 3.      Do you do Incircuit Testing immediately after SMD reflow or are
> there other operations such as for mixed technology, say wavesolder, or post
> wave assembly, etc., before your incircuit test?
>
> 4.      I guess the question here is do you even do Incircuit test?
>
> All inputs are most certainly appreciated.
>
> Thanks
> Ron Hollandsworth
>
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