All of these responses address fab pwb cleanliness and overlook a key
element; packaging.

It has always been a fundamental expectation that pwbs are expected to
arrive in a clean, dry condition, ready to go directly into production.
As part of this, packaging of the circuit boards for shipping should
include a tight hermetic wrap and seal of the pwbs in a "brick" that
includes a protective paper liner between each pwb within the brick, and
a dessicant pouch included. Some places have special requirements that
preclude the paper liner, in order to facilitate the unloading of the
pwbs from a magazine or mezzanine loader at the beginning of the line.
But no matter what the packaging requirements are, there should
certainly not be any scratches that expose copper, nor should there be
any milling residue, dust, dirt, bug potty or anything else that's not
on the pwb print. 
The reasons for the hermetic seal is to prevent oxidation of the
immersion silver, immersion tin, and certain other surface finishes and
to preserve the dry condition of the pwb.
If I received pwbs loose inside foam packaging, or simply wrapped but
not sealed, I would dry the boards by baking per J-STD-033. I really
have no idea what conditions these boards have been exposed to. For all
I know, they could have sat inside of a warehouse in the tropics
somewhere where the RH is >90%.

Its not just for components.

Somewhere in the acceptability requirements listed in IPC 6012B, 9199,
M105, PAS62250, and QE605A I'm sure there are words addressing these
fundamental, basic issues.

And I take exception to the statement that "there is no such thing as a
spotless board". Just what does that mean?
PWBs should not be "wiped clean". This just deposits lint and dirt into
the via holes, through holes, and packs dirt and dust into the gaps, say
between the soldermask and the pads for BGAs.

PWBs should be washed after all processing is done, and be tested on a
sampling basis for cleanliness.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Fineline Circuits,
Inc
Sent: Tuesday, June 14, 2005 1:05 PM
To: [log in to unmask]
Subject: Re: [TN] PCB rejection criteria

Erick:
Board fabricators generally touch up any scratched circuits that is
exposed with mask.
Also the dust you see may be from routing of the boards and they should
have been wiped clean before shipping.The vaccuum on the router may not
be working upto par or the dust collection may be full. There is no such
thing as a spotless board but they can be clean.You should let your fab
guys know that this is not acceptable for future orders.
Hasl with excess solder can be rehot levelled but they have to be in
panel form.
I would communicate with the fabricators of all these issues so that
they can take steps to correct it for future orders.It looks like these
boards were shipped without inspection.
Your issues are more procedure related and this does not add to the cost
of fabrication. These are all standard procedures followed by
manufacturer.
Sona Sitapara
Fineline Circuits Inc.

----- Original Message -----
From: "ekalgren" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, June 14, 2005 11:54 AM
Subject: [TN] PCB rejection criteria


> Good morning everyone,
>
>
>
> I've got a question on bare PCB's.  These are relatively simple boards

> that have been red flagged in incoming inspection for having scratches

> in the soldermask that expose the underlying copper.  Now, even I know

> that this is truly a defect.  QA has also written up the entire lot of

> boards for being dusty and a couple of the lot for having "excess 
> solder."  The excess solder is just a couple of PTH's that are 
> partially filled by the HASL.  I'm not sure what the dust is but it 
> blows off easily and doesn't seem to be affecting anything other than 
> the inspector's sense of cleanliness.
>
>
>
> My question to all of you out there is: how should I handle the dust 
> issue?
> Is this typical of boards coming in from the shop and should I tell 
> the inspectors to go easier in the future or do I demand spotless, 
> dust free boards from our supplier?  I don't want to accept junk but 
> at the same time I don't want to drive costs up by over inspecting. 
> Where does one draw the line?
>
>
>
> Thanks in advance,
>
>
>
> Eric Kalgren
>
> Manufacturing Engineer
>
> Continental Tool and Microwave Company
>
> [log in to unmask]
>
>
>
>
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