Ofer,

That would be a very long list and I don't know of any (good) comprehensive
ready-to-use list. Most are developed by the contract manufacturer or the
OEM from bad experiences. In the "olden days" the OEM I worked for would
send a team of 4 people to audit a supplier and we would be there for 3
days (and we didn't get it all)! I don't have that audit any more, but it
was like 40 pages or more....

Just as it is true that you can't inspect quality into a product, I believe
it is true that you can't audit quality into a process. Audits, to me, are
best understood as one of a continuing exchange between the supplier and
customer where the customer contiually learns the strengths and weaknesses
of their supplier and the supplier takes those constructive critiques and
goes back to the process to strengthen it.

I think, as did others who responded in the past, that there are many kinds
of audits; for instance, process, quality systems, technical capability ...

Theoretically any process or material that can be measured for some
property or feature would be a point for process control, and therefore
would be a point to audit. You audit for process control (Cp) and you can
also audit for process capability (Cpk) relative to your particular
products' requirements.

One approach would be to take a spec, like an IPC spec, and see all the
things that get checked or measured for a board to be acceptable, and then
take that spec to the fabricator and ask them how they *know* they are
meeting that spec - point by point ...

And take one of your fab prints and do the same thing: go through the shop
and have them show you where they are inspecting in the process for each of
the specific requirements on your particular board .... if possible, the
board should be an active part number in their shop and you should be able
to track it through their shop floor system and look at its' inspections.

And that would not catch everything, but it would be a very wide net ...
and unless you understand PCB processing you could really not be sure that
the inspection process they have implemented is effective.

The above is your first line of defense: strengthening the barriers against
defective product shipping to you. You still would be susceptable to ship
delays if they had a process out of control or had to scrap a lot in
process and remake it - you would not have audited the processes that
support the manufacturing efficiencies ...

I know I have rambled and not exactly answered your question - that's
because I can't. My belief (probably too fabricator centric) is that a pcb
fab process and facility audit needs to be done by someone who knows pcb
fabrication. Also, just writing the audit procedure and particulars is
itself a very time consuming process.

Today with staff cuts and "non-value-added" procedures discontinued, the
intensive audits of the past won't be coming back. The best one can do on a
audit these days is to "sample" the fabricators process and controls. Pick
some high points and do those; then go back after an interval, check the
progress on the corrective actions from the first audit, and then start
another sampling of another related set of procedures or go down a level
and audit there. Repeat as often as management will fund the travel.

Valerie







Valerie,
In continuation to a thread that was active here couple of weeks ago,
dealing with PCB shops audits: can you tell what are acceptable inspections
that the shop should implement in the different workstations - income
inspection, materials selection, kit inspection, etc.?

Regards
Ofer Cohen
Quality Assurance Manager
Seabridge Ltd.

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