micro pcb layout

[perts]

i have a motorola star 12 mcu (144 pins). What would be best place to put that on a pcb layout. some collegues want to be on the corner of the board farthest away from the voltage supply and regulators.

i want to have in the middle so it makes routing easier for the other devices and for spi clock distribution.

what are your guys feelings/experiences with this.

 

[sreid]

With a power and ground plane it should make no difference where any parts are relative to the voltge source. Parts placement is usually dictated primarilly for trace layout reasons. For this reason, putting the MCU in the center of the board would make more sense.

 

[logbook]

It’s the clock speed that is the biggest worry. If the I/O is running at hundreds of megahertz then the path lengths must be short. If it is running at less than 20MHz you can get away with longer tracks.

It is usually the analogue circuitry that gets upset by excess "bus noise" from the I/O. If there is no analogue circuitry then the only problem is getting the tracking onto the pcb.

What you haven’t said is why your colleagues want the chip up one corner of the board. This might help us give a more specific answer to the question.