Re: 320pin BGA Pin Layout suggestions

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.

Brian
----------------------------
Rising Technologies, inc.

.

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