Daan or others,
Could anyone refer me to articles, studies, etc. that demonstrate the
inefficiency of visual inspection and, if I remember correctly, the drop in
efficiency over time? I'm working on incoming inspection of bare
substrates - possibly an AQL type sampling, but have many concerns regarding
supplier lot quality, visual inspection efficiency, and product quality
requirements. Earl and I have been chatting about this for a bit now.
Another question, since I have your rapt attention... is it possible to
statistically equate lot quality (yield) to outgoing quality (yield)? In
other words, the supplier would have to produce product at xx% yield to meet
incoming requirement of yy% yield?
Best of the New Year to you all,
Jana Carraway
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of d. terstegge
Sent: Thursday, January 03, 2002 7:22 AM
To: [log in to unmask]
Subject: Re: [TN] Final Audit/Inspection
Hi Olivia,
You should be very happy if your inspection people catch more than 50% of
the defects. The remainder will simply be overlooked. This is not an
opinion, but it's a proven fact !!
It is just not possible to inspect quality into the product, instead you
should focus on the assembly process.
B.T.W. on my website I have some nice software available (it's a free beta
version) that may be helpfull for you with the inspection of the pcb's after
pick&place machine. The URL is
http://www.smtinfo.net/smtmaestro/smtmaestro.html
Daan Terstegge
SMT Centre
Thales Communications
Unclassified mail
>>> Olivia Mc Dermott <[log in to unmask]> 01/03 4:01 pm >>>
We do have inspection points throughout the process. The problem is they are
also missing defects and letting them through to final inspection.I wondered
if there is a direct instruction on inspecting.
1. you do this
2. you do this.
>From: Kathy Kuhlow <[log in to unmask]>
>Reply-To: "TechNet E-Mail Forum." <[log in to unmask]>
>To: [log in to unmask]
>Subject: Re: [TN] Final Audit/Inspection
>Date: Thu, 3 Jan 2002 08:49:32 -0600
>
>I would first start with some in-process sampling so you can pinpoint what
>types of defects the process is currently producing. Do you see more
>missing components from surface mount or do you have a problem withe solder
>shorts on the solder side because of wave issues or snapping problems.
>All to many organizations use a final inspection as a safety net. In my
>dream world I would have no one doing final inspection but bring it back to
>the process and do the inspection at the process through auditing by both
>production and quality personnel so immediate feedback can be accomplished.
> Otherwise you get data that is out of date and you can't really take
>effective corrective actions, especially if your world is as a CM or small
>run lots.
>
>If you must do a final inspection then we typically start with a complete
>part verification (value, polarity, AVL check) than solder (quality,
>quantity, lead placement) and finally any specific customer
>instructions(labeling, rev add, etc).
>
>Kathy
><< TEXT.htm >>
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