Multi Layer PCB 1

[shooter431]

I am looking for some information on multi-layer PCB's and potential problems that may come with more layers and possible manufacturers. We are currently using a 6 layer board made of FR4 material, and we have had some bubbling issues due to moisture, and RoHS soldering temperatures. We are looking at 8 and 10 layer boards for future products and I am wondering if this is realistic or will the problems grow exponentialy with each layer. Any feed back would be greatly appreciated.

 

[MacGyverS2000]

Your bubbling issues are a problem with your specific manufacturer (more specifically, their board supplier), not RoHS. If you stay with them and they don't change their methodology, of course you're going to see increased issues with increasing board layers.

I've dealt with 20+ layer board without issue, and I've seen projects that go upwards of 30+ layers, no reason why 8 layers should be a problem.


Dan - Owner

http://www.Hi-TecDesigns.com

 

[logbook]

Dan, I think the RoHS issue is to do with the soldering temperature. They use a higher temperature with the lead free solders and that makes a mess of some things like pcbs. PCB designs that used to be ok, can then become not-ok with the higher temperatures.

 

[MacGyverS2000]

Temps go up, what, about 20C because of RoHS? If the boards are so close to the edge they bubble with an extra 20C, I think there are larger issues to worry about as far as quality goes. I could be incorrect on this one, but I believe the laminate glues they use for standard FR-4 can handle the slightly higher temps without issue... someone please correct me if I'm wrong, though, as I'd love to have advance warning before I'm forced to deal with it.


Dan - Owner

http://www.Hi-TecDesigns.com

 

[shooter431]

He is absolutely right about the increased solder temps causing problems at least from what I am seeing at our facility. The 6 layer board has been in use for 4 years now, and up untill we converted to lead free solders and RoHS compliand boards we never saw a bubble. We went so far as to run boards from the same lot at RoHS temperatures and non-RoHS temperatures. The higher temp bubbled and the lower temp did not. We are trying baking and of course looking into the vendor's process control and eliminating causes one at a time.

 

[itsmoked]

Deja vu?? Didn't we just have this thread a week ago?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[shooter431]

You're right it was similar, this was meant to ask about the effects of more layers in relation to the problem, and to find information from people who have experience dealing with a large number of layers and potential pit falls concerning RoHS and lead free soldering. If I should have posted this in the same thread I apologize.