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. ý
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
______________________________________________________________________
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and may contain L-3 proprietary information that may also be defined as USG
export controlled technical data. If you are not the intended recipient, any
disclosure, use or distribution of its content is prohibited. Please notify
the sender by reply e-mail and immediately delete this message and any
attachments.
______________________________________________________________________
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