Using 6 layer board for BGA design

[Budda]

bga designing

I am in the process of finding and designing a new micro that will have a 256pin BGA with a 1.00mm pitch (21mm x 21mm). I was origanally thinking of using a 4layer board to do this with sig-pwr-gnd-sig. But after reading around it looks like i should be going to a 6layer board.

What would the layer stack be if i used a 6 layer board?? And can anyone provide any hints tips on fanout for this type of device??

Cheers Budda

 

[Al Farouk]

bga 256 fanout

we design a success similar board and the layer stack was as follows

1-(Top) signal layer
2- Ground plane
3- signal
4-signal
5- VCC plane
6-(Bottom) signal layer

 

[mr_ghz]

Re: BGA design

Hi Budda

We have designed several boards with 256-ball BGA's in the past. 6 layers are an absolute must, otherwise you won't have chance to connect to the inner balls. If your chip has more than one power supply (e.g. 3.3V and 1.8V) you often need more than 6 layers
The suggested layer-stack is surely OK, so the inner-layers are 'filtered' against the outer ones.

Bye

 

[meshmesh]

Re: BGA design

Motorola semiconductors also recommend 6 - 8 layers PCBs for its BGA processors .. I saw such thing in an AN for MPC860 PPC processor ( h**p://e-www.motorola.com/files/netcomm/doc/app_note/AN2100.pdf) .. also, the layer stack signal --> power -- > signal --- > signal ---> ground ---> signal is suitable and enough for single VCC BGA devices from my point of view .. 8)

 

[dainis]

Re: BGA design

Motorola semiconductors also recommend 6 - 8 layers PCBs for its BGA processors .. I saw such thing in an AN for MPC860 PPC processor ( attached ) .. also, the layer stack signal --> power -- > signal --- > signal ---> ground ---> signal is suitable and enough for single VCC BGA devices from my point of view .. 8)

Please post links ...
h**p://e-www.motorola.com/files/netcomm/doc/app_note/AN2100.pdf

 

[meshmesh]

Re: BGA design

Motorola semiconductors also recommend 6 - 8 layers PCBs for its BGA processors .. I saw such thing in an AN for MPC860 PPC processor ( attached ) .. also, the layer stack signal --> power -- > signal --- > signal ---> ground ---> signal is suitable and enough for single VCC BGA devices from my point of view .. 8)

Please post links ...
h**p://e-www.motorola.com/files/netcomm/doc/app_note/AN2100.pdf

Thank you very much for notification .. .. I modified the post ...

meshmesh