PCB Drilling: Definition, Types, and How It Works

Have you ever wondered what is behind the creation of printed circuit boards or PCBs? It involves a complex fabrication process, one of those steps being the drilling that shapes the board and prepares it for mounting components. Knowing more about this process is essential for anyone curious about PCB production.

PCB drilling is an important part of manufacturing Printed Circuit Boards (PCBs). It is a crucial part of creating a functional prototype, as it carves out spaces for components to be placed securely on the board. A drill bit or router with a controlled speed and power is used to create holes on the board.

In this article we will discuss PCB drilling – its definition, types, and how it works. We will also explore its role in creating circuit boards and how this process can be improved with emerging technologies. Understanding these details can help us appreciate the complexities associated with producing and assembling these components more accurately.

Table of Contents

What Is PCB Drilling?

PCB drilling is the process of creating holes in a printed circuit board (PCB) using drill bits. The purpose of these holes can vary from mounting components to allowing wires and other connections to pass through. The most common type of PCB drilling uses mechanical drills, although laser-based processes are also available for more precise applications.

Creating holes in a PCB can be done either manually or using an automated machine. This requires a specialized drill bit designed specifically for this purpose. In either case, it involves cutting away material from the surface of the board until it reaches its desired depth and shape.

Type of PCB Drill Tech

Drilling in PCBs (Printed Circuit Boards) can fall into two main categories: mechanical drilling and laser. Mechanical drilling is the most common type of drill used for PCBs. It involves using a rotating bit to cut away material from the board. Laser drilling uses high-energy pulses of light to precisely remove tiny amounts of material from the board without creating any heat or debris.

Mechanical Drills

Mechanical PCB drilling is a process used to drill holes into printed circuit boards (PCBs) using mechanical drills. The process involves using a drill bit to cut through the layers of the PCB to create holes for components or to connect different layers of the board.

In mechanical PCB drilling, the drill bit is typically made of tungsten carbide and rotated at high speed while fed into the board. The drilling process is controlled by a computer numerical control (CNC) machine that can precisely position the drill bit and control the drilling depth and speed.

There are different mechanical drills in PCB drilling, such as micro drills for drilling small holes and larger drills for drilling larger holes. The size of the drill bit used depends on the size of the hole required and the thickness of the PCB.

After drilling, the holes may be plated with copper to create electrical connections or filled with a non-conductive material to form vias. The quality of the drilled holes is vital for the overall reliability and performance of the PCB.

Therefore, careful control of the drilling process and proper maintenance of the drill bits are necessary to ensure accurate and consistent hole drilling.

Laser Drills

Laser PCB drilling is a process used to drill holes in printed circuit boards (PCBs) using a laser beam. This method is an alternative to mechanical drilling, which uses a drill bit to create holes in the PCB.

This non-contact process involves using a focused laser beam to ablate or vaporize the material of the PCB to create a hole. The laser beam is controlled by a computer numerical control (CNC) machine, which positions the beam precisely over the location where the hole is required.

There are several advantages to using laser drilling over mechanical drilling. For one, laser drilling is a non-contact process, which means there is no physical contact between the drill bit and the PCB, reducing the risk of damage to the board.

Additionally, laser drilling can create smaller holes than mechanical drilling, with diameters as small as 10 microns, making it useful for drilling small holes in high-density PCBs.

However, laser drilling also has some limitations. For example, it can be more expensive than mechanical drilling due to the cost of the laser equipment. Additionally, the process can generate heat, which can cause damage to the PCB if not adequately controlled.

Therefore, careful control of the laser parameters, such as laser power and pulse duration, is necessary to ensure accurate and consistent hole drilling.

Laser PCB drilling can be a valuable method for drilling small holes in high-density PCBs. Still, its use depends on the application’s specific requirements and the available equipment.

Type of PCB Drill Holes

Printed circuit boards (PCBs) typically contain two types of drill holes: plated through-holes (PTHs) and non-plated through-holes (NPTHs).

Plated Through-Holes (PTHs)

Plated through-holes are holes in a PCB that have been drilled through all layers of the board and are plated with a conductive material, such as copper. This plating allows you to make electrical connections between the different layers of the board.

PTHs are commonly used to connect surface-mount components to the board or create vias, holes that allow signals to be routed from one layer of the board to another.

To create PTHs, the drill bit is typically slightly larger than the desired hole diameter, allowing you to add the plating. After drilling, the hole is plated with copper by electroplating or using a chemical deposition process. The plating is then covered with a solder mask layer to protect it from damage and prevent short circuits.

Non-Plated Through-Holes (NPTHs)

Non-plated through-holes are holes in a PCB drilled through all board layers but not plated with a conductive material. People use NPTHs to mount through-hole components, such as capacitors or resistors, to the board or to provide mechanical support for the board.

Unlike PTHs, NPTHs do not require plating, simplifying the manufacturing process. However, the lack of plating means that NPTHs cannot be used to create electrical connections between layers of the board.

To create NPTHs, the drill bit is typically the same size as the desired hole diameter. After drilling, the hole is cleaned and may be covered with a solder mask or other protective coatings.

In summary, people use plated through holes (PTHs) to create electrical connections between the layers of a PCB. In contrast, people use non-plated through-holes (NPTHs) for through-hole component mounting and mechanical support. The choice of hole type depends on the specific requirements of the PCB design and the components you have.

Considerations in the PCB Drilling Process

PCB drilling is a critical process that involves creating precise holes in the PCB for component placement and electrical connections. Several considerations must be considered during the PCB drilling process to ensure the holes are drilled accurately and reliably.

Drill to Copper Clearance

copper traces in PCB

A critical consideration in the PCB drilling process is the drill to copper clearance. This refers to the distance between the edge of the drilled hole and the edge of any adjacent copper trace or plane on the board.

Insufficient clearance can cause shorts between the drilled hole and the copper, while excessive clearance can weaken the connection between the drilled hole and the copper.

To ensure proper drill-to-copper clearance, you must carefully plan the placement of copper traces and planes around the drilled holes. You must also consider the drill bit diameter when calculating clearance, as more significant drill bits require more clearance than smaller ones.

Aspect Ratio

Another important consideration in the PCB drilling process is the aspect ratio. This refers to the balance of the hole diameter to the thickness of the board. A high aspect ratio occurs when the hole diameter is relatively small compared to the board’s thickness, making it more difficult to drill the holes accurately and leading to issues such as drill breakage.

To address this issue, carefully choose the drill bit diameter and the board thickness to ensure the aspect ratio is within an acceptable range. The drilling process must also be carefully controlled to ensure the drill bit does not break during drilling.

Other considerations in the PCB drilling process include the drill speed, drill bit material, and the use of drilling templates to ensure that the holes are drilled in the correct locations. By carefully considering these factors, achieving high-quality and reliable drilled holes in a PCB is possible.

PCB Drilling Tips & Tricks

Here are some helpful tips and tricks you should keep in mind for PCB drilling.

  1. Mark the locations of holes on the printed circuit board (PCB) using a permanent marker or transfer paper.

2. Use an appropriate drill bit for the size and type of hole required, considering any specific requirements such as material thickness and heat dissipation needs.

3. Use a drilling template. A drilling template is a guide that ensures that the holes are drilled in the correct location. This can save time and reduce the risk of errors in hole placement.

4. Securely clamp down the PCB to ensure it does not move during drilling. Attach any necessary guides to ensure accurate positioning of holes drilled in relation to other components on board.

5. Set up your drill press at the correct speed for the type of material you are drilling, ensuring that you have firmly secured it before turning it on. 

6. Adjust the depth stop collar so only the desired amount of material will be removed from the surface when drilling begins.

7. Maintain the drill bit. Proper drill bit maintenance is essential for ensuring the holes are accurate and efficient. Keep the drill bit clean and sharp to reduce the risk of breakage or damage to the board.

8. Use a vacuum system. A vacuum system can help remove debris and dust from the drilling process, reducing the risk of drill bit breakage and ensuring the holes are clean and accurate.

9. Check the drill dept. It is vital to ensure that the drill bit is set to the correct depth to avoid drilling too deep or not deep enough. Use a depth gauge or a marking system to ensure the drill bit has the correct depth.

10. Test the drill bit. Before drilling holes in the board, test the drill bit on a scrap piece of material to ensure that it works correctly and that the speed and depth are appropriate.

11. Begin drilling slowly while applying gentle pressure until both sides have been completed. 

12. Use lubrication oil as needed throughout this process to help reduce friction caused by metal-on-metal contact between bit and workpiece materials which can cause damage over time if left unchecked. 

13. Inspect drilled holes for accuracy and clean up any burrs or sharp edges left behind with a file, sandpaper, or other abrasive material.


PCB drilling is an effective way to create intricate patterns and shapes on a printed circuit board. It uses specialized tools such as drill bits, routers, and milling machines.

Various types of PCB drilling are available depending on the application, including laser cutting, mechanical routing, and manual hand-drilling. While there can be some challenges regarding accuracy or complexity in certain applications, it works well when used correctly.


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