[PCB_FORUM] Re: Multi-layer stackup design

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

                         

                         


                 

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