Richard, Try the IPC designers council forum. You don't have to be a member to join the discussion. Jerry -----Original Message----- From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of richard moffat Sent: Wednesday, February 22, 2006 3:06 PM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Re: Multi-layer stackup design Re: BTW, is this Off-Topic? Are we allowed to discuss things like these here? Even though this is a Cadence forum, I find it's often one of the best for intelligent questions like this - unless someone can suggest a better one. >>> josemagnaye4@xxxxxxxxx 22/02/2006 5:56 p.m. >>> Yes, our standards specify at least 0.41mm if using a core material (laminate). If less than or equal to 0.40mm then we need to specify 3 layer prepreg (sorry for the wrong spelling before) but there were no minimum thickness specified. After asking several vendors we also found out that there are no published dielectric breakdown voltages for prepreg materials so we cannot compute for the minimum. Of course we can always use the 2.0mm PCB thickness but without proper justification ( i.e. literature or computed values), how can we convince our sales dept and the customer to go with the higher PCB price? BTW, is this Off-Topic? Are we allowed to discuss things like these here? - JM On 2/22/06, richard moffat <richard.moffat@xxxxxxxxxxxxxxxxxxx> wrote: 0.2mm? Possibly (dare I say probably without any legal ramifications?) The kind of spec it looks like you're referring to calls for 0.4mm. However, that figure is negotiable. Creepage distance on the outer layers is more troublesome. You're certainly doing the right thing by layering more than one prepreg. __________________________ Richard Moffat PCB CAD Manager Allied Telesis Labs ph. +64 (3) 3393000 richard.moffat@xxxxxxxxxxxxxxxxxxx >>> josemagnaye4@xxxxxxxxx 22/02/2006 3:51:48 p.m. >>> Hi Claude We're trying to design it to be as generic as possible since we will be using several vendors. They can define which materials they can use for the prepeg but the stackup design should be fixed. Basically what we are trying to determine if 0.2mm thickness will be enough for the 3 layer prepeg to withstand at least 1.5KV. On 2/22/06, Claude Meyers <claude.meyers@xxxxxxxxxxxxxx > wrote: This is a question you should be asking your fabrication house. Every PCB Fab house has different requirements. ________________________________ From: icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Jose Magnaye Sent: Tuesday, February 21, 2006 6:00 PM To: icu-pcb-forum@xxxxxxxxxxxxx Subject: [PCB_FORUM] Multi-layer stackup design Hi! We are designing an AC-DC power supply on a 4 layer board and we are currently looking at any literature on how to design the stack-up. Some of our primary and secondary tracks overlap and we were told that we can let them overlap as long as we use 3 prepeg layers in between. Unfortunately, we cannot find any info on the minimum allowed thickness of the 3 layers. We are concerned with the thickness since we will be using a 1.6mm 4 layer FR4 board with 2 Oz copper on all layers. JM NOTICE: This message contains privileged and confidential information intended only for the use of the addressee named above. If you are not the intended recipient of this message you are hereby notified that you must not disseminate, copy or take any action in reliance on it. If you have received this message in error please notify Allied Telesyn Research Ltd immediately. Any views expressed in this message are those of the individual sender, except where the sender has the authority to issue and specifically states them to be the views of Allied Telesyn Research. NOTICE: This message contains privileged and confidential information intended only for the use of the addressee named above. If you are not the intended recipient of this message you are hereby notified that you must not disseminate, copy or take any action in reliance on it. If you have received this message in error please notify Allied Telesyn Research Ltd immediately. Any views expressed in this message are those of the individual sender, except where the sender has the authority to issue and specifically states them to be the views of Allied Telesyn Research.