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First Pass Yields

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First Pass Yields | 9 November, 2006

Our SQE's want to benchmark the first pass yield requirements that we place on our CM's - currently they are at 95% - does this seem reasonable?

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First Pass Yields | 9 November, 2006

I would trust that you are benchmarking some design rules as well? Yield is directly related to design as well as process capability.

anyway 95% is not a bad first pass yield at all, and I would tend to think that that is a little high when dealing with unknowns.


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First Pass Yields | 9 November, 2006

Very much agree with Russ, Are your CM's doing final test and assembly? If so I would think that 95% is in the ballpark. If not, very much product dependant.

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John S.


First Pass Yields | 9 November, 2006

I would think it would be more productive to compare DPMO. Particularly across different products. A simple board of 20 components should yield much higher than a complex board of 200 components. Also, some consideration should be given to the difficulty. Component lead pitch, package size, density, board size, copper layers, design for manufacturing, etc all play a part in determining a first pass yield. As a guide, IPC developed a standard on how to calculate the DPMO on a product, as there were several different methods out there. Pick a method and be consistent in application. John S.

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First Pass Yields | 10 November, 2006

That is great point John, it definitely gets you closer to apples vs apples.

Remeber one time when we were compared to a another Mfgr that made a square box of plastic for one of our customers we made the PCB the fit into that box, we had wires, fine pitch, gluing applications, test, critical dimensions, elastomeric pads flatness concerns etc... this customer expected us to be the same as the box mfgr. Not going to happen.

When we got together and calculated opportunities for error between the two and then refigured, we were the same as box MFGr. and we got our little quality award!


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CK the Flip


First Pass Yields | 17 November, 2006

Typical of QE types. They don't know the entire process of qualifying what makes a "good" board (besides FPY), so they just arbitrarily come up with 95% FPY as a benchmark.

Russ made a great point that alot of yield issues are design-related.

Typical QE's. Failed Engineers who bring nothing to the table.

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First Pass Yields | 23 November, 2006

The DPMO is a far better measure -

first pass yield doesn't give you any indication on quality or effectiveness of test step.

If you want 100% first pass yield, test nothing - works every time - you see where I am coming from..........

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First Pass Yields | 24 November, 2006

Julie: What is the benefit of your SQE requiring that your CE meet your first pass yield targets?

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