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30 Layer PCB with 70% fallout. Are the 30% good?

30 Layer PCB with 70% fallout. Are the 30% good?

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Hello All, Well we have a critical PCB assembly ... - Jan 28, 2010 by jamyboy

We'd reject the lot, as an excuse to sit with our supplier a... - Feb 01, 2010 by davef

Hi Jamyboy, I would find out from DDI what the 70% was re... - Feb 01, 2010 by BoardHouse

Is it possible the 70% are marginal and the board shop is be... - Feb 02, 2010 by Stephen

First, why are they rejecting the boards? Are they rejectin... - Feb 02, 2010 by Reese

Remember this is a 30 layer PCB. If it is built in a multi ... - Feb 02, 2010 by Flipit

These are 30 layer motherboards and are 14" x 12". The PCB s... - Feb 03, 2010 by jamyboy

It stop sounding good to me at "30 layer PCB". ... - Feb 03, 2010 by Stephen

The strange part is that this shop produced these PCBs no pr... - Feb 03, 2010 by jamyboy

jamboy, sounds like their have been some quality and per... - Feb 03, 2010 by BoardHouse

jamyboy

#60963

30 Layer PCB with 70% fallout. Are the 30% good? | 28 January, 2010

Hello All, Well we have a critical PCB assembly with 30 layers being produced by DDI. We just received word from the PCB shop that this unit only yielded 30% or basically 70% failed. Should we keep the 30% yield or have the shop rebuild all and require a higher yield before shipment? I look forward to your thoughts on this issue....Thank you,

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davef

#60992

30 Layer PCB with 70% fallout. Are the 30% good? | 1 February, 2010

We'd reject the lot, as an excuse to sit with our supplier and try to determine the cause of the problem.

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BoardHouse

#60994

30 Layer PCB with 70% fallout. Are the 30% good? | 1 February, 2010

Hi Jamyboy,

I would find out from DDI what the 70% was rejected for,

Could have been a repeat issue due to a scratch in artwork or something like that.

I would not just jump and tell them to rebuild all until you know the facts.

DDI is a very reputable board shop and I could not see them wanting to ship you marginal product, especially at 30 layers due to the expense it would cost them if they failed at assembly.

Just my opinion coming from a Board manufacture.

Regards, Boardhouse

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Stephen

#61000

30 Layer PCB with 70% fallout. Are the 30% good? | 2 February, 2010

Is it possible the 70% are marginal and the board shop is being uber picky? I've seen a huge range of quality standards for board shops. And considering the cost of the boards I think a boardshop tour would be warrented to get firsthand knowledge of the situation. We recently toured a boardshop and it was informative.

And who thought that a 30 layer board would be a good idea? Just because something can be done does not mean it can be done well.

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Reese

#61002

30 Layer PCB with 70% fallout. Are the 30% good? | 2 February, 2010

First, why are they rejecting the boards? Are they rejecting them based on your acceptable limits or is it due to the standards they are using. Companies typically have standards that the board house must adhere to before shipping the product (depending on its application). If they are rejecting them based on your parameters, I would reject the lot, and like was mentioned, visit their facility to see what's going on. If they are using their own test standards, they may be too tight for your application, but I suspect the previous. I've never heard of a 30 layer board before. It sounds like a great product to test the effects of cross-talk and EMI interference.

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Flipit

#61007

30 Layer PCB with 70% fallout. Are the 30% good? | 2 February, 2010

Remember this is a 30 layer PCB. If it is built in a multi up panel, there is lots of room for error. Lets say there are 10 circuits per panel. Say you have a 10% scrap rate that happens randomly within the 10 up panel of circuits. Apply this 10% scrap rate to each one of the 30 layers. Each of the 30 layers will have 1 scrap unit out of 10. Stack up the 30 layers and your fallout will be most likely 100%. Have them explain what the scrap was caused by.

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jamyboy

#61011

30 Layer PCB with 70% fallout. Are the 30% good? | 3 February, 2010

These are 30 layer motherboards and are 14" x 12". The PCB shop is telling me that 70% failed due to random internal opens. Now they have started a new build and have random external opens that they want permission to "WELD" to repair? None of this sounds good to me....how bout you?

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Stephen

#61013

30 Layer PCB with 70% fallout. Are the 30% good? | 3 February, 2010

It stop sounding good to me at "30 layer PCB".

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jamyboy

#61015

30 Layer PCB with 70% fallout. Are the 30% good? | 3 February, 2010

The strange part is that this shop produced these PCBs no problem before DDI took over? I am still trying to get them to tell me what the expected yield is going forward..

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BoardHouse

#61017

30 Layer PCB with 70% fallout. Are the 30% good? | 3 February, 2010

jamboy,

sounds like their have been some quality and personal changes since C-tec was purchased by DDI.

I would look at having this board quoted at TTM in Chippewa falls,WI.

I have no affiliation with TTM, other than I know that they are able to build this type of product.

In regards to Welding I would say No, for the fact being if you agree to that you could end up with a board with a lot of welds if allowed them to weld signal layers. even if you allow 1 weld per. layer you could have a worst case potential of multiple welds in a board. I would not trust the welds with this layer count due to x,y & z expansion during manufacturing and Assembly processing even if they epoxy coated the welds the failure rate could be very high after finished assembly stess on them.

My thoughts,

Regards, Boardhouse

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