A circuit board drill is much like a common drill, except it is optimized for drilling holes in a circuit board as opposed to drilling holes in construction materials such as metal and wood. Unlike other drills, which commonly are made from steel, a circuit board drill is almost always made from tungsten because of its mechanical properties. The size of this type of drill can vary greatly, but it typically is very small. This drill sometimes is manually used, but it more often is combined with a drill press for automated drilling. Circuit boards sometimes need holes for installing parts or making it easier for the boards to fit into certain systems.
Tungsten is a very hard metal, which is why it is used to make circuit board drill bits. When a hole has to be drilled through a circuit board, the bit must go through copper traces, which are sturdy and hard. If steel were used, then it would rip the copper and tracing, and the steel itself would wear quickly. Tungsten is harder and can better handle higher speeds, so it can go through the traces without ripping them and will not wear as quickly.
Much like other drill bits, a circuit board drill can come in many different sizes. Circuit boards generally are small, so these bits typically are small, as well. Common sizes range from .0135 to 0.31 inches (0.3429 to 0.7874 millimeters), though there also are much larger sizes. As circuit boards get smaller, there has been a trend for the common sizes to shrink, as well, because smaller holes typically are needed.
Unlike a normal drill, for which manual use rarely is feasible, a circuit board drill can be used manually. At the same time, there are some disadvantages to not using a drill press. The drill is traveling slower, so it has a higher chance of ripping traces and, if the user bends the drill, then it may break. This means a drill press typically is smart to use if enough funds are available.
The reason for using a circuit board drill is obviously to drill holes through the circuit board, but these holes serve different purposes. Some parts cannot be installed on the circuit board without drilling holes for the parts to fit in. this can also increase the staying power of these parts, as they are able to hold onto more of the board. Not only that, but some systems may force users to place holes in the board so it can be properly installed.