What is hole-in-pad? Hole in the disk refers to the hole in the pad, the pad for the SMD disk, usually refers to 0603 and above SMD and BGA pads, usually referred to as VIP (via in pad). Plug-in holes in the pad can not be called a hole in the disk, because plug-in holes in the pad need to insert components to be soldered, all plug-in pin pads have holes.
With the development of electronic products to light, thin, small direction, the PCB board is also pushed to the high-density, difficult to develop, so the size of the components are gradually becoming smaller. For example: BGA components of the package is small, the pin spacing becomes smaller. Pin spacing is small, then the package inside the pin is difficult to get out of the line, you need to change the layer of perforation out of the line.
In the BGA pin spacing is small, can not fan out, there is only one way to solve the problem, which is to play the hole in the disk. There is also the BGA back to place the filter capacitor, when the BGA pin more than the back of the filter capacitor can not avoid the pin fan-out holes, only to accept the filter capacitance of the pad holes. Therefore, there are two kinds of holes in the disk, one is on the BGA pad, and the other is on the pad of the patch.
It is hereby recommended to try not to design a hole-in-disk if the spacing is sufficient, as the cost of manufacturing a hole-in-disk is very high and the production lead time is very long.
The design of the hole in the disk:
1、No need to design the hole in the disk;
Before PCB routing, it is necessary to do fan-out work first to facilitate the inner layer routing. For the fan-out of BGA type devices, the
The number of pins is too high, but the BGA area must be centered between the pads with the fanout holes. About BGA Fanout Settings
parameters, 0.15-0.2mm vias, 3-4 mil line widths, and 0.3-0.4mm hole loops, so the BGA pin spacing needs to be large.
The fan out can be normal only if it is less than 0.35mm.
2.Need to design the hole in the disk;
Before BGA fanout, we need to set the aperture diameter of via holes, otherwise the aperture diameter is not suitable for effective fanout, or
If the fan-out result is not normal, then the fan-out result is not normal. When the BGA pin spacing is too small to fan out, it is necessary to design a hole in the disk, and route the wires from the inner layer or from the center of the disk.
Underlay alignment for BGA devices.
Manufacturing process for the hole in the disk:
1. BGA above the hole is generally defined as a hole in the disk, you need to plug the resin, resin plating cap to facilitate customer soldering.
Unless the customer has requested that the holes above the BGA not be plugged.
2. Except for BGA, when the customer requires all the holes to be plugged with resin, the holes on the top of the patch are also defined as holes in the disk.
Hole in disk definition;
Production process;
Drill hole in disk → Plating hole copper → Plugging resin → Curing → Polishing → Copper reduction → Removing overflow rubber → Drilling other non-disk holes (usually component holes and tool holes) → Plating hole copper and VCP surface copper → Normal process ……
Plug-hole process capability;
Picture illustration of the hole in the disk:
1. BGA on the hole in the disk: Generally, devices with few pins do not require holes in the tray for the pins. However, for BGAs with many pins, the vias for the pins take up space in the wiring. If the vias are designed as holes in the tray and the holes are punched in the BGA pads, then space can be reserved for the wiring. Holes in the tray are designed when the pin spacing is too small to route the wires, and the wiring is routed from other places.
2. Hole-in-pan on filter capacitors: When many vias are required for routing in a BGA device, it is difficult to avoid the vias on the backside of the BGA device where the filter capacitors are plugged. Therefore, the vias are punched on top of the pads and become hole-in-disk.
3. Do not do the hole in the disk process: hole in the disk need to resin plug hole, and then plug the resin above the copper plating is conducive to welding. When the hole in the disk did not do the hole in the disk process, do not do the result of plugging the hole is a small welding area, the hole hidden tin beads or burst oil phenomenon, resulting in false welding.
4.Do the in-dish hole process: BGA pads are as small as redesigned in-dish holes, and there is basically no soldering area left. Therefore, the in-dish holes need to be plugged with resin, and electroplating is used to fill the holes flat, which is conducive to soldering and will not result in poor soldering.
