PCB manufacture
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Posted by rickman on April 10, 2008, 11:18 am
Please log in for more thread options wanted a single panel for prototypes, but it turned out I could get 6 panels for only $500 more. This would get me through the first round of production if I didn't need any changes. The day the maker was supposed to ship them, I got an email saying they had a poor yield and only got 116 good boards out of 7 panels vs the 132 I ordered. So now I have a concern about the quality of the boards. I was told the failed boards had problems with the plating in the 10 mil holes I used for vias. They claim that the "good" boards have no quality issues. My concern is that the vias may be marginal and open once they are temperature cycled a bit. I am not sure how to handle this with the vendor. I guess I could just flat out tell them that I am concerned with investing some $18,000 building up over 100 boards only to have my customer see failures in the field. I don't feel like they have done 100% on this since they did not provide the quantity I requested. They have offered to rebuild the entire set of panels if I am not happy with the result, but that would be a week delay. I also don't know if they are willing to let me use one of the current panels and remake the rest. Anyone have experience with 10 mil via holes and reliability issues? If you have a problem with an order like this, is it reasonable to use one panel and reject the rest? | |||||||||||||||||||||||||||||||||||||||||||
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Posted by linnix on April 10, 2008, 11:26 am
Please log in for more thread options As you have figured-out, pushing the process limit could be expensive. We would not go below 16 mil holes, even if we need bigger boards. Are you sure you can't use bigger holes? | |||||||||||||||||||||||||||||||||||||||||||
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Posted by rickman on April 10, 2008, 11:42 am
Please log in for more thread options > > Anyone have experience with 10 mil via holes and reliability issues?
> > If you have a problem with an order like this, is it reasonable to use > > one panel and reject the rest? >
> As you have figured-out, pushing the process limit could be > expensive. We would not go below 16 mil holes, even if we need bigger > boards. Are you sure you can't use bigger holes? Sure, I can use bigger holes. But I can't use bigger pads. It was hard enough to make the layout work with 10 mil holes and 24 mil pads. This board is very small and defined by the customer's requirements. It is a daughter card on an existing product so I have no flexibility in size except for extending one end which I have already done as much as possible. Even that does not do a lot for the density issue since the board is over 5 times longer than it is wide. Extending the length more just means I have longer lines to try to squeeze through the same bottlenecks around the chips and connectors. I guess I am confused about "process limits". I have seen vendors that claim to have capability for hole sizes down to 6 mil. They just say that they can't guarantee that the hole will not be plated closed which is fine with me. So I don't see where 10 mil holes should be a real issue. Did I pick a poor PCB maker? Am I just not grasping the realities of PCB manufacturing? | |||||||||||||||||||||||||||||||||||||||||||
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Posted by DaveN on April 10, 2008, 11:46 am
Please log in for more thread options >> > Anyone have experience with 10 mil via holes and reliability issues?
>> > If you have a problem with an order like this, is it reasonable to use >> > one panel and reject the rest? >>
>> As you have figured-out, pushing the process limit could be >> expensive. We would not go below 16 mil holes, even if we need bigger >> boards. Are you sure you can't use bigger holes? >
> Sure, I can use bigger holes. But I can't use bigger pads. It was > hard enough to make the layout work with 10 mil holes and 24 mil > pads. This board is very small and defined by the customer's > requirements. It is a daughter card on an existing product so I have > no flexibility in size except for extending one end which I have > already done as much as possible. Even that does not do a lot for the > density issue since the board is over 5 times longer than it is wide. > Extending the length more just means I have longer lines to try to > squeeze through the same bottlenecks around the chips and > connectors. > > I guess I am confused about "process limits". I have seen vendors > that claim to have capability for hole sizes down to 6 mil. They just Did the vendor you chose give this claim? If not then there's your problem, choose a different vendor. > say that they can't guarantee that the hole will not be plated closed
> which is fine with me. So I don't see where 10 mil holes should be a > real issue. Did I pick a poor PCB maker? Am I just not grasping the > realities of PCB manufacturing? > -- DaveN | |||||||||||||||||||||||||||||||||||||||||||
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Posted by DaveN on April 10, 2008, 12:00 pm
Please log in for more thread options >>> > Anyone have experience with 10 mil via holes and reliability issues?
>>> > If you have a problem with an order like this, is it reasonable to use >>> > one panel and reject the rest? >>> >>> As you have figured-out, pushing the process limit could be >>> expensive. We would not go below 16 mil holes, even if we need bigger >>> boards. Are you sure you can't use bigger holes? >>
>> Sure, I can use bigger holes. But I can't use bigger pads. It was >> hard enough to make the layout work with 10 mil holes and 24 mil >> pads. This board is very small and defined by the customer's >> requirements. It is a daughter card on an existing product so I have >> no flexibility in size except for extending one end which I have >> already done as much as possible. Even that does not do a lot for the >> density issue since the board is over 5 times longer than it is wide. >> Extending the length more just means I have longer lines to try to >> squeeze through the same bottlenecks around the chips and >> connectors. >> >> I guess I am confused about "process limits". I have seen vendors >> that claim to have capability for hole sizes down to 6 mil. They just >
> Did the vendor you chose give this claim? If not then there's your > problem, choose a different vendor. > Sorry, I meant did your vendor make the claim on 10mil? Additionally did you order 132 boards or the yield acheived from the panels? >> say that they can't guarantee that the hole will not be plated closed
>> which is fine with me. So I don't see where 10 mil holes should be a >> real issue. Did I pick a poor PCB maker? Am I just not grasping the >> realities of PCB manufacturing? >> The realities with any process is that as you approach its limits, you will get higher fallout; edges of the bell curve and all that. If your supplier is telling you that parts have failed then it tends to suggest that they have a reasonable quality system in place. They know the process and its limits and are therefore testing for those failures. It's an old but true saying that you can't test in quality, you can only design for it. -- DaveN | |||||||||||||||||||||||||||||||||||||||||||
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> If you have a problem with an order like this, is it reasonable to use
> one panel and reject the rest?