The printed circuit board (PCB) is the backbone of electronic circuits, and for complex circuits, multi-layer PCBs are utilized to enhance productivity. PCB drilling is a crucial process, especially in multilayer PCB production, and involves precise via creation through laminate material. We know that vias are important conduits that bridge the gaps between multiple layers of PCBs. These are considered the conductive connections in a PCB, especially if it has multiple layers. Without vias, the multilayer PCBs have limited design flexibility and are impractical. In PCB manufacturing, there are multiple drilling types, but today I am going to discuss the comparison between the two most important methods, i.e. mechanical drilling and laser drilling.
The appropriate drilling technique selection ensures the right hole placement, optimal hole quality and reliable performance. Lasers and mechanical drilling have their own merits and demerits. Drilling is a sensitive process, and even a small mistake can damage the PCB if the manufacturer does not keep the required measures in mind. Multiple factors affect the best choice between the two but choosing the best PCB platform can make this task easy.
PCBx Fabrication House is the leading platform that provides high-quality, low-priced PCBs and turnkey assembly services. PCBx offers all types of PCBs and has the prestige of presenting a seamless solution for laser drilling or mechanical drilling in PCBs. Drilling is a delicate process in PCBs, and we use advanced technologies for sharp, clean, and accurate drilling results, no matter if you are interested in laser drilling or mechanical drilling.
With the latest cutting-edge technology (including AI), the PCB order process is smooth, and we deliver the best PCBs with a smooth assembly and drilling process. Our top-notch automated inspection (SPI, AOI, and AXI) services make it possible for us to deliver the best products in mass production in the least time. With the 3D SPI, 3D AOI, and 3D AXI, the whole production process is under critical inspection to deliver the best product.
The latest technology not only helps to perform a smooth production process, but the top-quality drilling process is the prominent feature of PCBx services. So, if you want to get instant quoting, the most convenient ordering process, and top-quality drilling in your PCB, then you should check PCBx. Let me show you the face of the PCBx website:
The drilling process is crucial for multiple-layer PCBs, and we are offering competitive prices for drilling and multi-layer PCB production I would encourage you to try out our services and get the best quote not only for mechanical or laser drilling PCB manufacturing but also for assembly and design.
Now, let's discuss the comparison between mechanical and laser drilling and then choose the best option according to your needs.
The mechanical drilling in PCB production relies on the rotating bit tool to drill small holes in the laminated material. Usually, the drill bit can be used repeatedly because of its micro-granule cemented carbide structure. It can be reshaped and reused up to three times, depending on the type of PCB vias. In the case of mechanical drilling, the standard fiberglass and resin content laminate is used with a copper foil covering as a substrate, also termed FR4.
The drilling element in this method consists of the pneumatic mandril, which provides almost 300,000 rpm speed to the drill; therefore, high accuracy is required for holes of small sizes. For this, the drill is mounted on the servo-mechanical system so it may move along the X and Y axes. Moreover, the particular actuator works for the PCB movement in the Z axis. As a result, the user gets a smooth, clean, and accurate output.
Here is the list of common pros of the mechanical drilling process in PCBs:
The most common advantage is control over the hole depth with mechanical drilling. The bit tool penetrates deeper than the laser drilling hole. This is an important factor, especially if the manufacturer is working with a PCB with a large number of layers.
It gives high-quality holes consistently with the same sharpness, and it doesn’t matter how many holes are drilled.
The mechanical drill does not have any tapers at the end; therefore, the holes are completely drilled through the substrate without any bevels. As a result, the manufacturer gets a clean knee of the wall and a sharp edge finish.
This method allows the user to have a faster drilling speed than laser drilling, resulting in a good throughput level at a given time if all the preparations are done correctly. It works even better on PCBs with dense vias.
Now, let’s have a look at the negative aspects of this technique:
Mechanical drilling is an old and outdated method; therefore, it is not perfect for all types of projects.
When using mechanical drilling, the manufacturers have constraints on drill bit size, resulting in fewer via-size options. The narrow holes require a narrow drill, which has a great chance of breakage. For instance, if a high trace dense PCB requires less than 5 mils in diameter via holes, the required bits of diameter 0.008 inches, or 1/64ths of an inch, are too delicate for use in mechanical drilling.
Usually, the bits have a large size; therefore, this technique is not suitable for the latest, smaller but more complex PCBs.
If the right precaution is not taken, the mechanical drilling can cause tiny metal fragments (usually copper) that can stick to the PCB surface and affect its performance, so there is a need to clean the PCB after drilling.
There is a need to deburr the PCB vias after drilling, which is a time-consuming task.
It is an expensive method, and its preparation and post-processing are time-consuming.
Laser drilling is the PCB drilling process that consists of a complex optics set that makes holes in different PCB layers with 200 μm or even less. As a result, highly precise and sharp drills can be drilled in the PCBs. The size and diameter depend on the laser beam opening, and the exposure time of this bean determines the hole depth. There is a set of particular lenses that perform the duty of bean concentration on a particular point for PCB drilling. This drilling type allows the beam to create even micro vias, blind vias, etc. but also eliminates the delamination. The beam shaping technology is responsible for projecting the laser on the substrate, and as a result, this energy breaks the chemical bond. This process releases the steam that generates the recoil pressure and applies the downward force to the molten material. This results in the molten material flowing out of the hole, so the manufacturers get a clean and sharp hole.
The beam ablates a fine hole in the copper layer, following the substrate materials and the beam type is selected depending on the substrate type of PCB manufacturing. The two most common laser types are:
UV lasers
CO2 lasers
The ultraviolet lasers are more precise and find applications in high-density interconnect (HDI) PCBs. Not only for vias, but this method is considered ideal for PCB cuttings. Conversely, carbon dioxide (CO2) lasers are less expensive but have larger wavelengths. It finds its applications in dealing with different materials in PCB, such as plastics, ceramics, and composites.
Have a look at some important pros of laser drilling:
Laser drilling ablates through a large variety of substrate materials. Therefore, has a great scope for PCBs related to different industries.
It is a non-contact technology, and most processes are automatic; therefore, there are fewer chances of PCB breakage or damage.
Once the laser beam settings are done and the drilling process starts, there is no need for manual changes at every point but just supervision. The laser machine performs all the duties.
It has a high production rate because a large number of holes can be drilled into a single PCB at a time.
It is the latest technology and, therefore, suits the latest complex, smaller, and more advanced PCBs.
Here are some negative points about the laser drilling technology:
A metal stop layer is required in PCBs to halt the laser drilling process. Without this layer, the stopping process is challenging.
Lasers suit the smaller hole size because the chemical bond breakage requires a lot of time, effort, and energy.
The aspect ratio (AR) is the hole’s copper plating indicator, and there must be great accuracy in maintaining the AR ratio; otherwise, it’s difficult to get the ideal output. The formula for the AR is given next:
AR= Depth of the hole / Diameter of the drilled hole
PCBx offers the perfect AR ratio; therefore, our clients get a clean and sharp drilling process at all times, even for mass production.
Multiple factors affect the best choice for the particular PCB type. The following parameters will help you choose the best technology for your PCB manufacturing:
One of the most crucial points to consider while choosing the drilling technique is the size of the vias. As discussed before, laser drilling allows the manufacturers to drill small-sized holes with accuracy as compared to mechanical drilling. When studying the vias size, the two most important parameters to keep in mind are:
Pad to Hole Ratio=Hole Diameter/Pad Diameter
Aspect Ratio= Depth of the hole / Diameter of the drilled hole
Hence, mechanical drilling is suitable for PCBs with large vias and thicker borders otherwise, laser drilling works with smaller vias size.
This is the type of vias that goes throughout the PCB while manufacturing and the uncomplicated type of vias because there is no need to take care of the particular layer length. For the PCBs where the manufacturer has to create multiple through-hole vias, mechanical drilling is a better option due to its superior control and grip in depth. On the contrary, if the via size is small then you have to choose laser drilling.
The drilling technique must be according to the type of substrate and other PCB material. For instance, laser drilling can cause thermal stress or delamination in the substrate like FR-4 (Fiberglass) but for polyamide, laser drill is a good choice.
Mechanical drilling is effective for substrates like FR-4, metalcore, polyimide, etc but for the flexible substrate, laser drilling is preferred.
The cost is another fundamental criterion for choosing the best drilling technique for your PCB. Mechanical drilling and laser drilling are distinct each with varying operational costs. Although laser drilling provides more production and can deal with small vias effectively its processing cost is high and due to its complex handling, experts are required.
On the other hand, mechanical drilling is slow but it uses traditional machinery and costs less but the regular maintenance of drill bits and machine make it expensive for bulk orders. PCB manufacturers have the machinery for mechanical drilling which does not require much technical skills so usually, it costs less as compared to laser drilling.
Hence, the cost of any of these methods depends on the number of PCBs, via size, via type, and other parameters.
In PCB manufacturing, mechanical drilling and laser drilling are two of the major drilling techniques that are widely used in different PCB types. Mechanical drilling is a conventional, easy, and accurate drilling method that is useful for larger via size, hard substrates, and high AR, and pad hole ratios. On the other hand, laser drilling is the latest, cleanest, and most automated drilling technique. Different types of vias and their size play a role in choosing the right drilling technique. Each method has its demerits and drawbacks, and I hope I’ve cleared up different points. Now you can choose the best technique according to your PCB. If you want more assistance, you can contact us directly.
Hello everyone, I hope you all are doing well. In today’s tutorial, we are going to discuss the PCB Etching process, a fundamental step in PCB manufacturing. The PCB Etching process is used to remove the unwanted copper from the PCB surface to reveal the desired circuit pattern.
As we know, a PCB board has a complete copper layer in its raw form. We design our circuit in the software(i.e. Eagle, Altium, Proteus etc.) and place the pattern on the PCB board. This circuit pattern is normally protected by the tin plating, as shown in the below figure:
Now, there’s a need to remove the extra/unwanted copper layer from the PCB board and this process is called the PCB Etching Process. PCB Etching is carried out in various ways and the most commonly used is the Chemical Etching Process, where a chemical named Ferric Chloride is used to remove the copper. A completely Etched PCB is shown in the below figure:
Finally, we can remove the tin layer, polish the leftover copper layer (of our circuit), drill the holes and our PCB is ready for component placing & soldering.
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At PCBway Fabrication House, they provide real-time fabrication tracking for your orders so you can get the most satisfying and quick ordering process. Our professional workers know etching is a crucial step in PCB fabrication, and with the modernization of PCBs, they are becoming compact and complex, so etching provides accuracy and precision in the circuit design. Therefore, they follow the best practices and always get positive feedback for the services. For more information, follow the website’s link, and here is the main page:
The safe payment method and worldwide delivery are our prestige to satisfy the customers and work on bulk orders with the buyer’s protection. We deal with every type of PCB and provide multiple packages to grab the attention of every type of buyer.
In this article, I am going to discuss the introduction, types, workings, and other basic information that you must know before you get started with the etching process.
PCB etching is a highly intricate process in PCB fabrication that involves the removal of unwanted material from the PCB surface. It is the controlled dissolution or erosion of unwanted copper where the specific PCB areas of the copper layer are removed to get the required pattern. It is also termed PCB printing, where circuit patterns are designed on the surface for the electric components.
Before starting the PCB etching, there is a need to create the layout of the desired design for the board. Great care is required to create the exact design and layout, and then, it is transferred onto the PCB through a process known as photolithography. During this step, the PCB is coated with light-sensitive materials, and the pattern is then transferred to the board using light. As a result, the blueprint of the design is ready to be etched with sharp results.
PCB etching is part of the manufacturing stage of PCBs, and it takes place just before the electronic components are mounted on them. This crucial part forms the pathways necessary for PCB operations by defining the electronic connections. It is considered the last stage of PCB fabrication, and then the board is moved towards the assembly stage.
As discussed before, etching is the fundamental part of PCB manufacturing. For that reason, various etching techniques are employed for the specific type and material of the board. Understanding each of them ensures the manufacturer gets the required output and sharp design. Etching is broadly characterized into two major classes:
Wet etching
Dry etching
Let’s discover both these classes and the methods related to them.
The wet etching removes the undesired material from the PCB through chemical reactions. The next section will elaborate on its workings:
An etchant is a chemical substance that is used in the wet etching process to react with and dissolve the excessive material on the masked PCB. It is usually in liquid form; therefore, this type of etching is known as wet etching. Mainly, the etchants used in this method are acids, bases, or other solvents, and the selection of the right etchant depends on the type of PCB, masking, and some other important parameters. The following steps are required in wet etching:
The patterns we see on the PCB are formed by a layer of metal or oxide on the surface. At the start, a plain layer of this material is coated on the PCB along with the photoresists (coating layer) through photolithography. As a result, only the dischargeable areas of metal or oxide are exposed for the etching.
Now, when the board is ready for the dissolving process, it is immersed in the etchant bath, where the exposed material undergoes the reaction process. Usually, the metal layer made of copper and ferric chloride is the etchant. This is a relatively time-consuming process, and the total time depends on the type of etchant used in this step. As a result, the underlying layer starts showing. At this point, it is important to take the board out of the etchant solution bath.
After removing the substrate from the etchant solution, the board is thoroughly washed with water or other neutralizing agent to stop the chemical reaction.
This is the final step in this process, in which the photoresist layer is stripped away from the board and the user sees the desired pattern on the board.
Wet etching is a simple and effective method to get a precise design, but it requires a lot of care to avoid over-etching or underlying layer damage. Generally, the wet etching is isotropic, which means it etches in all directions. It requires a less complicated method and does not have strong ions; therefore, it has a low risk of board damage.
The following are the most common wet etching types:
The alkaline etching, or alkaline permanganate etching, utilizes an alkaline solution, usually NaOH (sodium hydroxide) and potassium permanganate (KMnO4). The solution dissolves the copper from the PCB, and this process is known for providing uniform etching at a high etching rate.
Usually, the manufacturers select this etching type in high-pressure and conveyorized chambers to improve efficiency and reaction rate. It is a good option for etching PCBs with an uncomplicated etching design and larger surface areas. Exposing the PCB to the refreshed etch spray within the chamber helps the manufacturer achieve less toxicity than with many other etching processes.
Acidic etching on PCB involves etching away unwanted copper from the surface through the chemical reaction of the acidic solution. The acidic solution can be applied to the PCB through different means, such as dipping it in the bath, spraying the solution on the board, or brushing it on the surface.
Once the acidic solution dissolves all the discardable copper layer areas, it is then washed and dried completely to stop the chemical reaction. Generally, the acidic method is considered best for the inner layer as it helps minimize the lateral erosion of the etched material of the masked metal layer. The chemical reaction is more controlled in this type; therefore, it provides an intricate and refined circuitry design. Manufacturers consider this method for smaller designs and dense boards because it provides a fine line width.
Dry etching is a technique in PCB that involves the removal of unwanted metal coating areas through reactive gases or plasma instead of liquid chemical reactions. It is a highly precise method to create sharp patterns and fine features on PCB. The most common methods of dry etching are described next:
Plasma etching has been used for PCBs since the 1960s but was not a prominent technique until the 1970s. This method was considered useful for reducing liquid waste disposal and getting sharper results as compared to wet etching. Another prominent benefit of using plasma etching is that it uses excitation and dissociation techniques to remove a particular part without causing damage to PCB surfaces. As a result, it is considered a good option for sensitive and delicate PCBs.
The method involves the use of a plasma system, also known as the plasma chamber. A high voltage is applied to the reactive gases such as oxygen (O2), chlorine (Cl2), argon, fluorine, etc., which break down the molecules into the constituent gas atoms. For this, the plasma system has a radio frequency source that produces electromagnetic waves. Some of these atoms are ionized (acquire charge) and then react with the exposed metal layer. As a result, the discardable copper molecules are broken down and removed. Mostly, the frequency range is 13.56 Mhz, 40 Khz, 80 Khz, 100 Khz, and 2.45 GHz.
The process does not involve any chemicals and is a dry, clean, and effective method for etching. The positive points of this method are that it is a clean, controlled, and precise method for etching that can be applied on small scales. Unlike some other techniques, there is no risk of vias contamination or solvent absorption. Moreover, it works better on high-density printed circuit boards, often utilized for fine-line circuitry. On the contrary, it is an incredibly costly technique and is not profitable until the etching is done in large quantities regularly. The chamber system requires maintenance and expertise.
Laser etching is also termed laser ablation or laser direct imaging (LDI) and was used at the start of 1987. It is the process in which a high-power laser beam is incident to the PCB surface to remove the unwanted copper layer and get pinpoint accuracy. It is a computer-controlled method, and the excessive copper is either evaporated entirely or flaked off.
On a larger scale, laser etching has the following sub-types:
Fiber Laser
Ultra Violet Laser
CO2 Laser
Ventilation, eye protection, protective clothes, laser beam reflection maintenance, and limited direction viewing are some of the fundamental precautions required to apply this method. A benefit to using this method is that the number of steps in the whole process is very minimal if all the precautions and machinery are ready to use. No ink, acid, toxic material, or wet chemical is required for this process.
The disadvantage is, that etching the large board is challenging. Moreover, it requires a lot of investment at the start to get the equipment and system ready. The operational cost is also high in this process.
The following table shows the difference between wet and dry etching for the printed circuit board:
Feature |
Wet Etching |
Dry Etching |
Process |
A liquid chemical solution is required for etching |
Gas, plasma, and lasers are required for the etching |
Etching Material |
Liquid chemicals (e.g., acids, alkaline solutions). |
Reactive gases or plasma. |
Material Removal |
Isotropic (removes material uniformly in all directions), can lead to undercutting. |
Can be anisotropic (directional etching), providing more precise control. |
Equipment |
Requires chemical baths, masks, and washing stations. |
Needs vacuum chambers, plasma sources, and more sophisticated equipment. |
Cost |
Generally lower cost due to simpler equipment. |
Higher cost due to complex and high-precision equipment. |
Applications |
Preferred for use for large-scale material removal in simpler PCB designs. |
Preferred for high-precision applications, especially in advanced and complex PCB designs. |
Advantages |
|
|
Disadvantages |
|
|
Etching is one of the most basic steps in PCB manufacturing, in which the excess copper layer is removed from the PCB surface to get the desired circuit design. A copper layer is applied to the PCB, and, a mask of unreactive material is applied to the areas required on the board. The unneeded part is then allowed to react with the etchant and is dissolved. After that, the solvent is then removed and dried if required, and masking is then removed. As a result, sharp and fine designs are obtained. Etching is broadly classified into wet and dry etching. Examples of wet etching include alkaline and acetic etching, whereas dry etching includes plasma and laser etching. The choice of method depends on the board size, density, type of board, etc. Each method has its merits and demerits, and we have discussed all the basic points to clear up the topic.