Hi Phil:

We have found that the effectiveness of manual physical inspection to be
approx 80% when compared to AOI.

If you look at literature in human factors such as ( Hardy,
& Cooper, 1989; Spencer & Schurman, 1994) you will find similar results.

Ask 100 operators to count a bag of marbles with 200 pieces in a single
attempt you will have a distribution of "counts" on your hand.

Bob W


On Tue, Oct 22, 2013 at 4:17 PM, <[log in to unmask]> wrote:

> Bob,
>
> I am alarmed when you state visual inspection is only 80% effective.  I
> expect much higher effectivity from my inspectors.
>
> When combined with xray, you should be able to achieve 100% inspection
> given enough time is permitted to look at all connections.
>
> With 100+ PWAs, and 4000 parts/PWA, I would not hesitate to utilize teams
> of inspectors and sub-regions for their inspection area requirements.
>
> If you have time as a luxury, then programming a 5DX and training that
> team also works well.
>
> Phil
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Wettermann
> Sent: Tuesday, October 22, 2013 1:16 PM
> To: [log in to unmask]
> Subject: [TN] Inspecting Class 3 Assemblies
>
> Dear Technetters:
>
> I think these things come in bunches.
>
> We are being asked to perform contract inspection of Class 3 medical PCBs.
> I would categorize this board as "high complexity" with BGAs, UHDI
> connectors, 0201s and about 4,000 parts. There are 100+ boards.
>
> Obviously performing this manually will would take many hours and based on
> previous experience, be only 80% effective using a single set of eyes.
>
> So my question for those of you building IPC-A-610 Class 3 product for
> mil, aerospace or medical is how do you insure that class 3 solder joint
> and other inspection criteria are met? The AOI we have will not do the
> trick!
> The leadless devices and BGAs we will inspect via XRAY. Other ideas for
> doing this "offline"?
>
> Bob W/BEST
>
>
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-- 

   1. Bob Wettermann

847-767-5745


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