Types of Drill used in PCB Board Manufacturing

The most costly and time-consuming step in the production of circuit boards is drilling. This is due to the fact that the procedure needs to be followed precisely in order to guarantee the greatest quality levels. A manual or laser PCB drill is typically used for different cut outs. They can either be outline, holes or may be PCB internal cut out shape.

In the production of PCBs, drilling is essential. Bad electrical connections or even a board breakdown might result from poorly drilled holes. High-precision through, blind and buried hole drilling enables manufacturers to satisfy the requirements of contemporary compact designs as electronic devices become more intricate and smaller. We've examined the types of PCB drills used in the PCB manufacturing process in depth to give you a better understanding of the procedure.

Why Drilling Matters in PCB Fabrication

The main purpose of drilling in PCB manufacturing is to make holes for mounting points, tooling holes, vias, and through-hole component leads. These holes might be blind, buried or through-hole. All the types of via’s and holes are covered in a separate article, you can see the difference and their working here. As HDI (High-Density Interconnect) boards proliferate, drill precision has to be within micron-level tolerances. Which provide dependable mechanical integrity and electrical performance. The electrical operation of the board may be impacted by problems like misalignment, delamination or poor plating adhesion because of improper drilling.

The Drilling Process:

There are 20 essential phases in the intricate process of making a printed circuit board. Drilling often occurs in the beginning of this process, following the cutting of substrate raw materials to size and the determination of the PCB's necessary thickness.

Tooling pins are used to hold the board in place when it is in the pre-programmed computer numerically controlled (CNC) machine after the substrate has been ready for drilling. The PCB is then separated and precisely measured after the component mounting holes have been drilled in it. Lastly, the copper's surface is cleaned using a conveyorised polisher to get rid of any tiny burrs or jagged edges. After completing the drill procedure, another production process starts. During all this PCB has to pass the quality control checks.  

Types of PCB Holes: Through Hole, Blind Hole, and Buried Hole

1. Through Hole (Via):
The most prevalent hole type on PCBs is a through hole, or via. By joining copper layers on various board layers, it permits electrical impulses to flow between them. These vias guarantee an electrical connection between all the layers and passes also through the dielectric layer. Which makes it the deepest hole required in PCB, depending on the size proper equipment can be chosen.

2. Blind Hole:
Although it does not extend completely through the board, a blind hole joins the PCB's outer layer to one or more interior layers. It is referred to as "blind" as it is impossible to look through it from one side to the other. It is utilised in HDI (High-Density Interconnect) boards to fit more circuitry into constrained locations and conserves space by connecting just the layers that are required.

3. Buried Hole:
Buried holes connect internal layers without reaching the surface of the PCB. They are completely hidden inside the board. It allows even more compact and dense PCB designs by keeping internal connections invisible from the surface. It is the most expensive type due to complexity but essential for high-density, multi-layer PCBs used in advanced electronics.

Types of Drills Used in Precision PCB Manufacturing

1) Mechanical Drills (Carbide Drills)

Mechanical drilling is the most common method used in standard PCB manufacturing. Solid carbide drills are typically used due to their hardness and wear resistance. It provides a variable hole size 0.15 mm to 6 mm (depending on board design). The speed can go up to 100,000 RPM in advanced CNC drilling machines. And used in general-purpose through-holes, via formation in multilayer boards and component leads. Although it is quite accurate and cost effective, it is not suitable for extremely fine holes (<0.2 mm in many cases).

2) Laser Drills (UV and CO₂ Lasers)

For microvias and high-precision blind/buried vias, laser drilling has become the preferred technology, particularly in HDI and flex PCB manufacturing. Either it will be a UV laser or CO2 laser, UV Lasers are used for drilling through resin and thinner copper layers and CO₂ Lasers on the other hand for cutting through thicker dielectric layers and certain plastics. It can provide a hole size as small as 20 µm (~0.02 mm). Yes it is extremely precise, but comes with higher equipment cost and slower rate of drilling.

3) EDM (Electro Discharge Machining) Drills

EDM drilling is occasionally used in specialized PCB manufacturing processes. Particularly where exotic materials or extremely hard substrates are involved. It uses electrical discharges to erode material, rather than cutting it mechanically. It is very rare are in standard PCB manufacturing; sometimes used for specialized metal-backed PCBs or ceramic substrates

4) Controlled Depth Drilling

Controlled Depth Drilling is used when precise partial-depth holes are required, commonly for blind vias or specific cavity structures in multilayer boards. It is very precise and uses layer-to-layer targeting. But requires advanced CNC programming and verification processes.

Types of PCB Drill Bits in PCB Manufacturing:

In addition to material, the particular needs of your PCB design will determine the kind of drill bit you use. The primary kinds and their applications are as follows:

Standard Twist Drill Bits:

They have a spiral configuration for effective chip removal. The most often used PCB drill bits are standard twist bits. Most component leads are covered by typical diameters, which vary from 0.6 mm to 3.0 mm. They are adaptable and perform admirably on conventional FR-4 boards with through-hole components.

Micro Drill Bits:

Used in high-density PCBs or microvias, micro drill bits are made for tiny holes, frequently less than 0.5 mm. To maintain accuracy at such small sizes, they are nearly invariably constructed of carbide and need high-precision machinery.

Step Drill Bits:

Step bits are used to drill holes of different sizes all at once. Although they are less frequently used in PCB fabrication. They might be helpful for unique designs that call for countersunk holes.

Router Bits:

Unlike conventional drill bits, router bits are used to shape PCB edges or cut holes. Although they are not appropriate for regular hole drilling, they are necessary for intricate board designs.

Carbide vs HSS Drill Bits:

The drill bit's substance has a significant impact on its functionality and robustness. Let's contrast the two most popular choices:

Carbide Drill Bits:

When it comes to expert PCB fabrication, carbide drill bits are the preferred option. These bits are perfect for drilling through difficult materials like FR-4 fibreglass boards because they are made of tungsten carbide. Which is exceptionally robust and resilient. Here are a few main advantages:

● Extremely durable: It can last up to 10 times longer than HSS.

● Stays sharp which ensures clean and precise holes even after drilling hundreds of times.

● Handles high heat: At drilling speeds between 30,000–80,000 RPM, it can handle the system well.

High-Speed Steel (HSS) Drill Bits:

Drill bits made of high-speed steel (HSS) are composed of an alloy of steel. They can withstand high temperatures and speeds. These are less expensive options, however there are trade-offs:

● Cost-effective for light-duty work.

● Less brittle than carbide better if your setup isn’t perfectly precise.

Conclusion

Drilling is a crucial step in the PCB manufacturing process. If done incorrectly, the device cannot be placed on the circuit board due to an issue with the hole's passage. As we can see, through, blind, and buried holes are the most often used drilling techniques on printed circuit boards (PCBs).

Controlled depth drilling and EDM drilling are two other technologies that may be used with certain materials based on the applications. To meet the increasingly demanding quality standards in modern electronics, partnering with an experienced PCB manufacturer is essential. JLCPCB utilizes advanced CNC drilling machines, laser systems, and strict quality control to ensure precision in every hole—no matter how complex your design. JLCPCB delivers accuracy, speed, and affordability all in one service.