In my humble opinion and 30+ years of inspecting boards, nothing beats 
the eye.    A well trained eye can catch defects quickly,  the BGA is 
another anima, for that X-ray is the ticket.    I have found over the 
years that 60/40 or 63/37 are much easier to detect then is the lead 
free, most likely since I have more experience with the leaded variety. 
I find using 2-5X for a cursory view and then follow up with a 40x view 
when a defect is suspected.    I have taught several technicians at work 
what to look for.


A lot says for the thin black line.

pat

On Tue, Oct 22, 2013 at 6:04 PM, Tan Geok Ang wrote:

> Agreed but not much people appreciate operator jobs (especially in 
> Asia). If you know how to train them to mark, they are priceless!
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
> Sent: Wednesday, 23 October 2013 6:49 AM
> To: [log in to unmask]
> Subject: Re: [TN] Inspecting Class 3 Assemblies
>
> Not if you know where to look. I have worked with amazing inspector in 
> the past. High level technician, not normal operators. They are 
> priceless.  ‎
>
>   Original Message
> From: Robert Kondner
> Sent: Tuesday, October 22, 2013 6:31 PM
> To: [log in to unmask]
> Reply To: [log in to unmask]
> Subject: Re: [TN] Inspecting Class 3 Assemblies
>
> Phil,
>
> I would disagree. People are not robots. They miss stuff. They get 
> distracted. My guess would be 50% of errors can go through undetected.
>
> How many times has this happened to you:
>
> 1. You have a bunch of boards to inspect, you do 25% of them then you 
> notice a problem.
>
> 2. You then go back through the boards you found OK and you find some 
> of the same problems you just found.
>
> I think it is very common.
>
> Finding a problem once you know where to look is a lot easier. But 
> until you know where to look it easily gets missed. Consistent 
> problems are easier.
> Random failures are very difficult to catch. When using ICT machines I 
> would get a piece of paper telling me there is a short on two nets. 
> Sometime you need to check and check, it is hard to find. But the 
> short test on an ICT machine is pretty darn good. When it says there 
> is a short you can count on a short. And when it says the board is 
> good, it is pretty darn good.
>
> Bob K
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
> Sent: Tuesday, October 22, 2013 5:17 PM
> To: [log in to unmask]
> Subject: Re: [TN] Inspecting Class 3 Assemblies
>
> 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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> Phil,
>
>  I would disagree. People are not robots. They miss stuff. They get 
> distracted. My guess would be 50% of errors can go through undetected.
>
>  How many times has this happened to you:
>
>   1.  You have a bunch of boards to inspect, you do 25% of them then 
> you notice a problem.
>
>  2. You then go back through the boards you found OK and you find some 
> of the same problems you just found.
>
> I think it is very common.
>
> Finding a problem once you know where to look is a lot easier. But 
> until you know where to look it easily gets missed. Consistent 
> problems are easier.
> Random failures are very difficult to catch.  When using ICT machines 
> I would get a piece of paper telling me there is a short on two nets. 
> Sometime you need to check and check, it is hard to find. But the 
> short test on an ICT machine is pretty darn good. When it says there 
> is a short you can count on a short. And when it says the board is 
> good, it is pretty darn good.
>
> Bob K
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
> Sent: Tuesday, October 22, 2013 5:17 PM
> To: [log in to unmask]
> Subject: Re: [TN] Inspecting Class 3 Assemblies
>
> 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
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud 
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> [log in to unmask] 
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> is prohibited. Please notify the sender by reply e-mail and 
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