how to Calculate BGA routing layer ???

[kabaleevisu]

Hi ,
in my BGA has 484 pin is available.how to Calculate BGA routing layer requirements ?? i red one document but i could not understand 4 point.any body can explain clearly ??
here i post the guideline
Calculate BGA routing layer requirements
?Select ball size
?Subtract ball size from ball pitch
?Calculate number of traces between pads
?Add 1 for outside row of pads
?Subtract via size from ball pitch
?Calculate number of traces between vias
?Add 1 for outside row of pads
?Add via and pads escapes together
?This is the number of rows that can be routed in
2 layers
?Number of traces between vias for additional
rows per layer

 

[SHABU]

Hi kabaleevisu,

4th point describes to add the outer row pad through which one trace can be taken.

Summing all your above points.

You have 12 rows and 12 columns right. if you can route 2 traces in between your two vias(fanouts)
you can take 22 traces inbetween the twelve row balls and 2 traces from the corner balls. Totally you can take 24 traces from one side of BGA.
similarly you have to calculate for all the four sides... Adding all four sides you will get number of traces in layer.
From this you can calculate the total number of layers needed for your BGA.

Shabu

 

[marce]

https://www.pa.msu.edu/hep/atlas/l1...ntorpaper_bga_breakouts_and_routing_52590.pdf

READ THIS

 

[sivamani]

refer
**broken link removed**

also

 

[marce]

Sivamani, that link is a bit dated now, they have 1.27mm as the most popular pitch (I wish), though some of the picture of routing are cool.

 

[sivamani]

Yes but you can use this as a base reference

 

[kabaleevisu]

what is base reference

 

[marce]

Post #3 has a link to one of the best books on BGA design, I downloaded it and used it as a reference for future BGA designs, though having done this for 27 years and laid out boards with PGA's and understand the mechanics of PCB design it is no problem for me. You need to read the reference data and have a play with a real PCB and creating components and the geomatires involved. Try things and you will learn.