256-Ball Ball Grid Array, Thermally Enhanced [BGA_ED] (BP-256) Dimensions shown in millimeters a A1 CORNER INDEX AREA 27.00 BSC SQ 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 24.13 BSC SQ 3 2 1 A B C D E F G H J K L M N P R T U V W Y BALL A1 INDICATOR TOP VIEW 4 BOTTOM VIEW 1.27 BSC DETAIL A 1.00 0.80 0.60 DETAIL A 1.70 MAX 0.70 0.60 0.50 0.10 MIN COPLANARITY 0.20 SEATING PLANE COMPLIANT TO JEDEC STANDARDS MO-192-BAL-2 041906-A 0.25 MIN (4 ) 0.90 0.75 0.60 BALL DIAMETER