Need_Layer_Stackup_help

[hot_snow]

Hello,

Yesterday,I finished routing my board with this layer stackup:

TOP/GND1/SIG1/SIG2/GND2/SIG3/PWR1/BOT.

Some people told me that this stuckup is assymmetrical and may be my board didn't work, others told me that they used this stuckup before and their boards work fine.

I need to know your opinion about this.

Regrads,

 

[etmabreu]

There is nothing wrong with the stackup itself. If you experience problems, may be they are due to incorrect routing or careless routing especially with high frequency paths.

 

[hot_snow]

Well, it's the first time that I make a multilayer board, when I finished the board,Altium inform me that I have many dead copper in my board (unrouted GND&Power nets)

Knowing that I'm working with 3 power levels and with high frequency conditions.

 

[anilrock87]

Hi,
Are you using any polygon pour for ground or power nets.

 

[hot_snow]

Hello,

No yet, in fact I'm confused how can I dilever the 3 power levels and GND polygon pour in my PCB with a better way

 

[pstuckey]

When you have a signal layer opposite to a gnd or pwr layer there is some asymmetry in the amount of copper. I've done this in the past too, and on the advice of the board fab, just added some ground pour to the signal layer to make the copper areas more similar. The recommendation that I got from my fab house was 60% copper area, but you should check with whoever is doing your fab for their recommendation.

 

[senilicus]

Try to make your board symmetrical. in core and prepeg thicknesses and copper weight. This will reduce bow and warp. On a small board it will not be a problem, but when your board gets bigger it might become an issue.