Let’s discover how to drill holes in PCB at home. PCB drilling is an interesting and intriguing procedure from various perspectives. Consequently, it captivates technical hobbyists for greater exploration. It is necessary to utilize correct drilling techniques and procedures, as the incorrect implementation of PCB drilling techniques can potentially harm the electronic circuitry.
Explanation of PCB drilling procedure
The process of drilling holes in the PCB is a very technical procedure that requires precision and care. This process is carried out before soldering the electronic components on the board. Various easy drilling methods are commonly used for drilling holes in PCB surfaces at home.
Types of Drilling Methods
The standard drills available in the market are not suitable for drilling holes in PCB. Therefore, specialized drills are used for this purpose. Twisted drills are used for drilling holes that range from 0.1 to 4.0mm, while slotted drills are used for hole sizes ranging from 1.5mm and 2.5mm. A typical drilling method used for drilling at home leads to excellent and flawless results in less time.
Tools and Materials used in PCB drilling
Normal drills available in the market are not used for drilling holes in PCB. Twist drills and slotting drills are used for drilling holes in the PCB. High-speed steel (HSS) and tungsten carbide (WC) are usually considered drill bit materials for the drilling of holes in the PCB. The cemented carbide drills are preferably used in the process of PCB drilling.
Different drill holes in PCB
A blank circuit board can possess a range of manufactured characteristics, which may encompass cut-outs, slots, and the ultimate shape of the completed board. The most widely used feature is the holes that are drilled into the PCB. The intended use of these holes can be categorized into three groups:
Tiny metal-plated openings are known as vias. They serve as stations for transmitting electrical signals, power, and ground throughout the layers of the circuit board. These vias are of various types based on their intended purpose. The types of vias are discussed below:
- Thru-hole: This is commonly used via, traversing the complete board layer stack from top to bottom. Thru-hole vias can connect with traces or planes on any one of the internal layers required.
- Buried: These vias originate and terminate within the internal layers of the board. Although they require less space as compared to the traditional thru-hole vias. This attribute renders them advantageous for use in HDI circuit boards.
- Blind: It originates from the external layer but enters only partway through the board. Similar to buried vias, they also have greater fabrication costs, but they generate space for routing and their shorter barrel can increase the signal strength of high-speed transmission lines.
- Micro: This via has a smaller aperture as compared to the other vias because it is created by using a laser. Microvias are usually limited to a depth of two layers due to the complexities of plating smaller openings. These are mandatory for HDI boards that need to escape vias placed in their solder pads.
Surface mount components are usually used for the majority of active and discrete elements on the circuit boards. These components have connectors, switches, and other parts that are required for mounting. Furthermore, component holes are preferred for power components like substantial resistors, capacitors, op-amps, and voltage regulators because of their ability to handle current and heat dissipation.
A circuit board features various mechanical components like brackets, connectors, or fans that need holes for secure attachment. Typically, these holes aren’t metal-plated, but they can be if the attached component necessitates an electrical link with the board, as is the case with chassis grounding. In certain situations, these mounting holes serve to dissipate heat generated by “hot components” into the inner plane layers. Additionally, mechanical holes also aid in the board’s manufacturing process.
10 Steps to Drill Holes in PCB at Home
Follow the following nine steps for drilling holes on the PCB at home:
Step 1: Drilling initial holes on the PCB
In the starting phase, begin with pilot hole drilling before proceeding with the actual drilling, it helps prevent the drill bit from “wandering,” which occurs when the drilling deviates from the intended direction. A perfect pilot hole can be drilled by using a small drill bit or opting for automation with a drill press. When a drill press is used to create pilot holes, the tool systematically removes the drill bit heads one by one, for example, if a 0.2 mm drill bit is used, four of them will be required to create a single hole. Additionally, with the removal of each head, a small metal mark is left on the surface of the PCB.
Step 2: Drill bit precisely positioned for drilling at an exact angle
Straight drill bits are considered to be an effective method for drilling at an angle. These drill bits are often supplied in sets having various diameters. The following measurement dimensions are commonly followed in this step:
- A wire gauge drill bit is used that is designed for wires having thicknesses ranging from 0.8 to 1 mm.
- Small drill bits are offered in both flat and round profiles that are suitable for creating holes with diameters ranging from 0.7 to 2 mm.
- Medium-sized drill bits are designed for holes having a thickness or diameter ranging from 2 to 10 mm.
- For larger holes of 5 mm size or more, a larger drill bit is used.
Step 3: Must utilize an accurate-sized drill bit
It is very important to ensure that the drill bit size used for your PCB is accurate. A large-sized drill bit leads to the risk of damaging the components on your circuit. Conversely, if the bit is too small, it will drill small holes that would be too narrow for the wires to pass through. Using a drill bit of an accurate size leads to the best wiring and circuitry system.
Step 4: Choose a drill bit with constant speed and power
The rate at which you can create a hole in metal is dependent on the force and velocity of your drill. The common options for selecting a drill bit with relevant speed and power are listed below:
- Fast-paced drill bit: This type of bit can rapidly drill through metal, but extended usage can lead to issues.
- Steel drill bit: These bits are used to drill larger holes.
- Electroplated drill bits: These are used for drilling the circuit boards, plating, producing holes in thick boards, and utilizing a high-frequency air hammer.
Step 5: Must utilize a drill press at all times.
The best way of achieving accurate holes is by employing a drill press. These machines commonly use a standard industry bit. They can operate at a very high speed. If it is used in this method, then the hole-drilling process will be quick and perfect.
Step 6: Completely comprehend how to operate a drill press
Drill presses have different pricing and features, but they all share the common function of applying limited pressure to drill through metal. Greater force can lead to quicker drilling. Various drilling techniques, such as “cross drilling,” “plunge drilling,” “ventilated holes,” and “inclined ends,” are just a few examples of drill press. It is necessary to ensure that the drill bit is oriented upwards and the angle aligns with the holes in the PCB.
Step 7: Be conscious during the process of drill holes in PCB
Drilling holes in a circuit board can be challenging without the use of accurate materials and tools. It is necessary to wait during the drilling process. It is mandatory to ensure that the drill bit operates at a suitable speed. Moreover, wearing safety goggles during drilling is beneficial for the eyes and it prevents vision impairment as well.
Step 8: Wipe the PCB after drilling the holes
Once the drilling process is finished, it is necessary to use a brush and solvent. The brush and solvent will be used to clean the holes. This step is important for removing any metal shavings created during the PCB hole drilling. This thorough cleaning ensures that the PCB board is fully prepared and safe for use.
Step 9: Administer solder to the openings on the PCB
To create powerful electric connections in the PCB, apply solder to the freshly drilled holes. Then melt the solder with the soldering iron. Guide a wire through one of the holes and apply heat to ensure proper adherence to the solder. This process prevents the solder from seeping through the perforations, gently press downward to confirm that it has been completely attached.
Quality Regulations Should Be Followed in PCB Drilling
Ensuring the high quality of the holes is highly important for the proper functioning of the PCB. Several quality features are checked that are discussed below:
The diameter of the drilled holes
- It is the exact hole size that is required.
- It needs proper tool wear and machine settings.
- It needs the standard tolerance requirement that is ±0.025 mm.
Accuracy of the position used for drilling holes
- The difference between the center of the hole should be according to the design and to the hole position accuracy.
- It should be according to the precision of the drill guide.
- The typical tolerance requirement for the hole position accuracy is ±0.05 mm.
Wall of the Barrel Hole
- The barrel hole wall should never be tapered or an hourglass-shaped plated hole.
- It can result from uneven plating thickness.
- It can impact hole resistance.
The circularity of the hole
- It is important to inspect the hole’s circularity.
- Comparison of the maximum and minimum hole diameters should be along the perpendicular axes.
- A value approaching 1 shows a high level of circularity.
The smear of the Drill
- It is the resin residue that is re-deposited on the inner wall of the hole after drilling.
- It affects the adhesion of copper plating and electrical conductivity.
- It is the gap or separation seen around the exit point of the hole on the outer layer.
- It occurs when the drill enters the final laminate layer.
- It can influence the quality of pad connections.
The creation of personal PCBs is accessible to anyone using the right equipment and materials. Mastering this valuable skill can be achieved by practice and precaution. To ensure the timely completion of circuit boards for various projects, it is essential to have accurate tools. Tools like, drills, drill presses, saws, and PCB solder stencils are considered the best tools for conducting PCB hole drilling.
What is the standard drilling tolerance?
The standard drilling tolerance is ±0.075mm. there are variations within this tolerance range, such as -0/+0.15mm -0.05mm/+0.1mm.
Will the size of the plated through holes in the finished PCB be the same as they are in the design?
The hole sizes in the design will be similar to the hole sizes drilled on the PCB. Typically, 0.1mm to 0.15mm plating tolerance is considered for all via and component holes to ensure a reliable product.
How to guarantee perfect alignment between NPTH (non-plated through) holes and other PTH holes?
Drill NPTH holes parallel to the PTH holes to prevent any misalignment between PTH and NPTH holes. Ensure that NPTH holes remain un-plated.
Can overlapping holes be incorporated in the design?
Many designers use overlapping holes in the drill layer for slot information instead of creating a separate layer. This method is not recommended because it can create confusion during the manufacturing procedure. The overlapping drill holes are removed before the production of the final design. It is advised to provide slot information in a separate layer, such as mechanical layers.
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