Re: 320pin BGA Pin Layout suggestions

In article <1174349279.008603.302420@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
w3gate@xxxxxxxxxx says...
On Mar 19, 3:35 am, "Joe G \(Home\)" <j...@xxxxxxxxxxxxxxx> wrote:
Hi All,

I am looing at laying out 320pin BGA on a PCB like this one.

http://www.standardics.nxp.com/packaging/package.outlines/pdf/sot824-...

The pitch between balls is 0.5mm. The internal cpu speed is 220MHz but the
external I think is ~60MHz.

It has a JTAG port

Questions
Q1
How many PCB layers would you recommend and why

Q2
Is there anything else I should watch out for?

Any other pointers on this beast would be appreciated.

Regards
Joseph

My suggestion will be a bit more practical tha others. Absolutely use
no less than 6 layers. Being new to it, you will end up chewing up
your ground/power planes and will have EMI issues if you try 4. Even
an experienced layout guy would most likely use 6, I know I probably
would unless I was using very few pins. The reason is simple: it ends
up a better design. For you, it will be a less frustrating experience
to learn with 6 layers and you will definitely have a better design.
Don't think I am calling you incompetent, most times parts like these
just aren't good candidates for 4 layer boards.

Use a stack up as in Figure 6 here... http://www.hottconsultants.com/techtips/pcb-stack-up-3.html

Thats my advice.

Got a reason, other than some hand waiving? I don't see any reason
for more than five. Four might be simple, depending on the power ball
layout.

--
Keith

.

Relevant Pages

  • Re: gEDA suite vs my creaky old Protel Client 3.5?
    ... 8 layers, or 6 plus two power planes, although if you want a complex ... A new, GTK-based version of PCB is slated to be ... it does lack a couple of features present in commercial tools. ... the project manager "geda" is still buggy. ...
    (sci.electronics.cad)
  • Re: V Cut for multiple layers PCB
    ... I need second opinion about V Cut for multiple layers PCB. ... each copy of my design. ... I've had no problems with this, but usually the inner layers are power ...
    (comp.arch.embedded)
  • Re: V Cut for multiple layers PCB
    ... I need second opinion about V Cut for multiple layers PCB. ... each copy of my design. ...
    (comp.arch.embedded)
  • Re: PCBCAD17
    ... Schematic and PCB entry with auto convert schematic to pcb ratsnest. ... RS274X Gerber file generator and NC drill file generator. ... Auto component placers for minimum routing. ... copper layers. ...
    (sci.electronics.basics)
  • Re: PCBCAD17
    ... Schematic and PCB entry with auto convert schematic to pcb ratsnest. ... RS274X Gerber file generator and NC drill file generator. ... Auto component placers for minimum routing. ... copper layers. ...
    (sci.electronics.basics)