drilling pcb FAQ
pcb drill press
An accurate drill press is an essential tool for making your own . through-hole printed circuit boards at home.
The solution that we arrived at was to use a Harbor-Freight Pneumatic 1/8" Micro Die Grinder. and attach it in-plane with a precision linear slide rail. The Micro Die Grinder runs at 56,000 RPM and has the 1/8" collet that I needed for the PCB drill-bits.
The keep the die-grinder in-plane with the rail. we decided to mount the linear rail to a self-centering drill-press jig.
Build the Drill Mount and Attach It to the Slide
We removed the excess sides of the self-centering drill press jig. and sanded all the rough edges smooth. The THK rail mounts along the center. We used the measurement between the holes to drill through the drill mount.
how to drill a hole
In pcb design, the hole is consist of two parts. one is the drill hole in the center area, the other is the pad around the drill hole. The size of these two parts determine the hole size. in the design of a printed circuit board with high speed and high density. the designers always hope that the holes the smaller the better. so that it can leave more space for circuit layout. But the hole size decrease will bring the increase of the pcb fabrication cost, moreover. the hole size is impossible to decrease. because it's limited by the process of drilling and plating. The smaller hole size, the longer drill time required, and the easier off center position. When the depth of hole is more than 6 times of hole diameter. the copper plating process won't guarantee. that the hole wall could plate copper . For example, a standard 6 layer PCB with thickness (depth of the hole) about 50 mil, so the PCB manufacturer. can provide the minimum hole diameter to 8 mil.
Now we drill the holes for leaded components and the via holes that link the copper layers together. First we use an X-ray drill to locate targets in the copper of the inner layers. The machine drills registration holes to ensure. that we will drill through the centre of the inner layer pads.
To set up the drill the operator first puts a panel of exit material on the drill bed. This stops the drill tearing the copper foil as it comes through the PCB. Then he loads one or more PCB panels, and a sheet of aluminium entry foil.
The drilling machine is computer-controlled. The operator selects the right drill program. This tells the machine which drill to use and the X Y co-ordinates of the holes. Our drills use air-driven spindles which can rotate up to 150,000 revolutions per minute. High speed drilling ensures clean hole walls to provide a secure base for good plating on the hole walls.
Drilling is a slow process as each hole must drilled . So depending on the drill size we drill a stack of one to three PCB panels together. We can drill holes down to 100 microns in diameter. To give you an idea of the size, the diameter of a human hair is about 150 microns. Drill change is automatic. The machine selects the drill to use from the drill rack, checks that it is the correct size. and then loads it into the drill head.
Once all the holes drilled the operator unloads the panels from the drilling machine. and discards the entry and exit material.