Countersink Hole is used in PCB board that sink the screw head into PCB laminate.so that the board looks clean and flat.countersink hole generally has two types of shapes.V figure Count-sink and T figure Count-Sink.
Which side of countersink hole be drilled? Like Bottom Layer?
Countersink hole PCB
The CAM file of countersink hole:
1. Editing of routing layer:
It is important to know the depth of countersink hole, it will be drilled into the layer which need be cut copper at inner and outer layers for NPTH, and whether it affects electrical performance for PTH. Usually, the depth tolerance also needs to be taken into account when calculating the depth of the countersink hole.
For example, NPTH countersink hole needs to be drilled from top layer to the fourth layer, then the L1-L4 must be according to countersink hole without leakage copper and cutting copper to make an inner and outer layer. Such as hole diameter is 4.5mm, the inner layer does not leak copper with cutting copper 0.2mm so that the inner hole corresponding to the overall size of the cutting copper should be 4.9mm.
2. Editing of the solder mask layer
If it is NPTH, the welding window shall be opened at least according to the NPTH hole corresponding to the countersink hole. If it is PTH, the welding window shall be opened properly according to the outer layer of the countersink hole. If the customer does not design the mask window, it is necessary to confirm the normal window opening according to the welding pad.
For example, 4.5mm NPTH countersink hole, be drilled from the top layer, if the normal NPTH hole welding resistance window is larger than the hole with 3mil, then the corresponding countersink hole top layer welding resistance window is 4.5mm+0.15mm=4.65mm.
3. Countersink hole files output notice
When the countersink hole is drilled at the bottom layer, the drill hole output must be mirrored.
4. Process instruction
PTH countersink hole is usually done by after standard drilling.
NPTH countersink hole is usually placed in front of the milling process.