PCB Drill: PCB Drilling Techniques & Process

What is PCB Drill?

A PCB drill is a specialized tool used to create holes, or vias, in printed circuit boards (PCBs). PCB Drill holes are essential for mounting components and establishing electrical connections between the board's layers. Typically made from durable materials like tungsten carbide, PCB drills are designed to handle the precision needed for drilling through copper and other PCB materials.

PCB Drilling

PCB drilling is the process of creating PCB holes according to design specifications. The holes can be used for fitting through-hole components, connecting different layers via vias, or for mounting the PCB. The process requires high accuracy and can be performed using mechanical drills or advanced methods like laser drilling, depending on the PCB’s complexity and requirements.

PCB Drilling Techniques

Mechanical Drilling

Mechanical drilling is the most widely used technique for standard PCB drilling. This method involves using tungsten carbide drill bits that rotate at high speeds to create holes in the board. It is effective for creating through-holes, blind vias, and buried vias. Mechanical drilling is ideal for standard, low-complexity PCBs with larger holes.

Laser Drilling

Laser drilling is used for high-precision applications, such as creating microvias on multilayer PCBs. The laser beam can penetrate multiple layers with extreme accuracy, making it suitable for boards with complex designs and tight space constraints. Laser drilling is perfect for HDI (High-Density Interconnect) boards where components are densely packed.

Plasma Etching

Plasma etching is used for drilling microvias and blind vias. It involves using plasma to remove material and create vias without the physical contact of a drill bit. Plasma etching is highly precise and reduces mechanical stress on the board, which is especially beneficial for delicate and thin PCBs.

Do's and Don'ts of PCB Drilling

When drilling PCBs, following best practices ensures the accuracy, reliability, and longevity of your circuit boards. Here are some essential do's and don'ts to keep in mind:

PCB Drilling Process

The PCB drilling process is a multi-step procedure that requires precision and equipment to ensure the functionality and reliability of the circuit board. Here's an overview of the key stages involved in drilling PCBs:  

Step 1: Drill the Pilot Holes

Pilot holes keep the bit stuck in position when drilling. Without them, the bit will walk and damage other board parts. We recommend laser drills for tiny holes and mechanical twist drills to punch large holes (0.1mm to 4mm). The former doesn’t need pilot holes.

Step 2: Pick The Most Suitable Drill Bit and Consider the Size

You can use any straight drill bit to punch an angled hole. But wire gauge drill bits are ideal for holes ranging from 0.8 to 1mm. Flat or round small drill bits have a wider range of 0.7-2mm, and any hole 2mm or wider requires a large drill bit.

Also, electroplated bits are ideal for creating holes through thick PCBs using a high-frequency air hammer.

High-speed bits are handy for drilling through metals like copper but can get hot when used for long periods. But, high-speed steel bits can withstand more heat, making them suitable for making wider holes through one or multiple thin boards.

Step 3: Use a Drill Press

Instead of holding a drill manually, we recommend using a drill press to maximize accuracy.

Step 4: Clean the PCB After Drilling

Clean the holes and board surface using a brush and solvent to remove the shavings.

Step 5: Solder the Drilled Holes

Insert the component’s lead into the hole, then melt just enough solder above to attach the pin. The joint should be solid after cooling and drying. Validate this by squeezing the component slightly and checking if it shakes.

Types of PCB Drill Holes

PCB drill holes can be classified based on their ability to carry current, but it’s more practical to categorize them by their specific uses:

Non-Plated Through-Holes (NPTH)

• Countersink Holes: Used to mount boards where the bolt head needs to be flush or below the surface.
• Mounting Holes: Designed for installing mechanical fasteners without requiring vertical clearance.
• Fasteners: Ideal for mechanical justification or confirming proper component installation that needs additional support.

Plated Through-Holes (PTH)

• Thermal Vias: These do not conduct current but are crucial for removing excess heat by leveraging copper's high transfer rate, especially from high-power components.
• Through-Hole Vias: Used to route traces from the surface through any layer within the board stackup, facilitating signal routing throughout the layers.
• Buried Vias: Create connections between internal layers without extending to the surface.
• Blind Vias: Provide electrical connections between internal layers and the surface, extending only to targeted layers.
• Microvias: Smaller vias that can be either buried or blind, essential for high-density signal routing due to their size.
• Press-Fit: These holes accommodate through-hole component leads without the need for soldering or filling.

Types of PCB Drilling Tools

The typical drill bits used on PCBs include the following.

1. Twist Drill Bits

Twist drill bits are the most commonly used tool for mechanical drilling. They feature a helical shape that allows for efficient cutting and chip removal. Twist drill bits come in various sizes and are ideal for creating larger vias in single-layer and multi-layer PCBs.

2. Micro Drill Bits

Micro drill bits are used for drilling extremely small holes, typically found in HDI boards. These bits offer high precision, allowing manufacturers to create tiny microvias essential for complex and compact circuits.

3. Diamond-Coated Drill Bits

Diamond-coated drill bits are designed for drilling through tough materials like ceramic or glass-reinforced substrates. The diamond coating ensures durability and precision, making these bits perfect for high-performance and advanced PCBs.

4. Carbide Drill Bits

Carbide drill bits are known for their strength and longevity. Carbide drill bits are highly durable and can handle repeated drilling without losing precision, making them ideal for mass production. They are commonly used in fiberglass PCBs, ensuring clean cuts and accurate hole placement.

5. PCB Miniature Drill Bits

Miniature drill bits are specifically designed for creating small, delicate holes in compact PCBs. These bits are used in applications where space is limited, such as smartphones, wearables, and other portable electronics.

Contact OurPCB

At OurPCB, we use cutting-edge technology and the best drilling techniques to ensure accurate, high-quality PCBs for a wide range of applications. Whether you're producing standard boards or advanced multilayer designs, our team ensures reliable performance with every product.