<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div>I needed a minimum of a 6 layer PCB to achieve my PCB design.<br>Basically, the top layer brings the two outter most rows of BGA connections out from under the chip and most of the remaining inner BGA connections are handled by vias connections to the other 5 layers.<br>I can send you an image of the underside of the A10 if you like.<br><br>Robert </div></div></body></html>