The hole in the pad refers to the hole punched on the pad, which is an SMD pad, usually referring to SMD and BGA pads of 0603 and above, commonly referred to as VIP (via in pad). The solder pad of the plug-in hole cannot be referred to as an in tray hole, as the plug-in hole solder pad requires the insertion of components for welding, and all plug-in pin solder pads have holes.

　　With the development of electronic products in the direction of light, thin, and small, PCB boards have also been pushed towards high-density and difficult development, so the volume of components is gradually decreasing. For example, if the packaging of BGA components is small, the spacing between pins will decrease accordingly. If the pin spacing is small, it is difficult to wire the pins inside the package, and it is necessary to change layers and punch holes for wiring.

　　When the spacing between BGA pins is small and cannot be fanout, there is only one solution, which is to drill holes in the tray. There is also a filter capacitor placed on the back of BGA. When there are many BGA pins, the filter capacitor on the back cannot avoid the through holes fanned out by the pins, and can only accept punching on the solder pad of the filter capacitor. Therefore, there are two situations with holes in the disc, one is on the BGA pad and the other is on the patch pad

　　No need to design holes in the disc

　　Before conducting PCB wiring, it is necessary to perform fan out work to facilitate internal wiring. For BGA type devices, the number of pins is too large, but the BGA interval must have the fan hole in the center position between the pads. Regarding the setting parameters for BGA fanout, the through-hole is 0.15 to 0.2mm, the line width is 3-4 mils, and the hole ring is 0.3 to 0.4mm. Therefore, the spacing between BGA pins needs to be greater than 0.35mm in order to fan out normally

　　Need to design holes in the disc

　　Before BGA fanout, we need to set the aperture of the via hole, otherwise the aperture is not suitable and cannot be effectively fanout, or the fanout result is abnormal. When the spacing between BGA pins is too small to fan out, it is necessary to design holes in the disk to route wires from the inner layer or the bottom layer of the BGA device.