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我有一篇关于BGA封装的文章。 有5个design rules. 1.Maitain all BGA pad sizes between 0.018 to 0.020 inch, with track interconnections between 0.006 to 0.008 inch. 这和C6x的BGA的PAD有冲突。我在接GND时，一般用12mil的线。 2.Make the solder-resist aperture layer between 0.004 to 0.006 inch larger than the BGA pad to give normal clearance 但以前有人说要去掉BGA上的阻焊层？ 3.Corner marks are required, with widths of about 0.008 to 0.010 inch, positioned half under the edge of the BGA outline. 这个corner markk是什么？位置在那？ 4。etch the marks into the copper layer, since this will provide accurate alignment with the BGApad pattern.avoid using legengd marks. 这是干吗？ 5.A teardrop pad-used to connect to the track allows you to easily interpret X-ray inspection results.It also allows the solder ball and solder paste to wet away from the pad during reflow. 这段我也不懂，何为teardrop pad? paste mask 是什么？