Rob,
based on my understanding, the class 1, 2, 3, is performance (design)  
requirement, attached link of 6013 showed example of flex requirement  
of 1,2,3.  Normally, there is a price difference attach to the  
different class (quality, inspection, sampling plan.  Appendix A is a  
useful check list for the differentiation.  In my past life, I would  
have 2 vendors, one for class 3 and one for class 2, depend upon the  
requirements.  For some hi-mix low volume, hi-rel, go to the class  
3.  Pay a bit more to sleep well at night.  Vendor qual for the class  
2, would not be used for such a job.  Most of the class 2 job can go   
to both vendors.  I would not use class 1 for any jobs on my hand (no  
moisture, no current carrying test, etc.).  Being said, I was not  
making toys at the time.
http://www.ipc.org/html/IPC-6013Amendment1Published4-00.pdf
                               jk (my 2 cents)
On Sep 19, 2007, at 5:28 PM, Rob Strecker wrote:

> Let me rephrase the question.
> What is the benefit of moving from a class 1 to 2 or class 2 to 3?
>
> Rob
>
>
>
> -----Original Message-----
> From: Guy Ramsey [mailto:[log in to unmask]]
> Sent: Wednesday, September 19, 2007 10:58 AM
> To: 'TechNet E-Mail Forum'; Rob Strecker
> Subject: RE: [TN] Reliability of Class 1,2,3
>
> I don't think you are understanding the requirement. Do you have
> J-STD-001?
> SPC is required if you are not going to do 100% inspection. If you are
> doing
> SPC then your quality team and statistical process results will  
> tell you
> what you need to do.
>
> A place you might look for help is the text, Statistical Process  
> Control
> for
> Surface Mount Technology, by William S. Messina.
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Rob Strecker
> Sent: Wednesday, September 19, 2007 12:05 PM
> To: [log in to unmask]
> Subject: Re: [TN] Reliability of Class 1,2,3
>
> Kat,
> Actualy we are looking at ways to reduce inspection and still  
> maintain a
> class 2.  Does IPC have anything on method and frequency of  
> inspection?
>
> We may do something similar to what you have done, develop an  
> inspection
> matrix for our products to determine critical inspection points.  I
> guess
> the question is if we were to eleminate inspections completely (we  
> would
> still maintain 20% inspection end of oven, or some form of it)  
> could we
> still say we work to class 2, when we only look at the boards if they
> fail
> test?  How can we say we work to any class if we don't look at the
> boards?
>
> Rob
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Kathy Kuhlow
> Sent: Wednesday, September 19, 2007 9:00 AM
> To: [log in to unmask]
> Subject: Re: [TN] Reliability of Class 1,2,3
>
> Rob,
>
> I would think a class change to reduce inspection is the wrong  
> approach
> since the class only has to do with acceptability criteria instead of
> method
> and frequency.
>
> Can you support reduced or implement inspection sampling plans? I have
> also
> been able to reduce inspection labor through critical and high risk
> feature
> identification so that labor is put towards those items needing more
> attention.
>
> Can you provide more detail on the inspections that you want to  
> reduce?
>
> Kat
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Rob Strecker
> Sent: Wednesday, September 19, 2007 9:15 AM
> To: [log in to unmask]
> Subject: [TN] Reliability of Class 1,2,3
>
> I was wondering if there is any documentation out there stating the
> reliability of products built to IPC class 1 compared to class 2 or 3?
> We are a class 2 manufacture and are looking at reducing our
> inspections,
> however will this put us in the class 1 category by default if we only
> catch
> defects at functional test?  What inspection must we do in order to
> maintain
> class 2?
>
>
>
> Thanks,
>
> Rob
>
>
>
>
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