3 Types Of Printed Circuit Board Fabrication Process Flow
A printed circuit board (PCB) is a type of circuit board that emerged in the early 20th century as an electronic component. It allows various electronic components and conductors to be created through a printing process, thereby forming circuits with specific functions. Its characteristics include high wiring density, lightweight, thin thickness, and good flexibility. The manufacturing process of PCBs mainly involves three types: single-sided PCB fabrication, double-sided PCB fabrication, and multi-layer PCB fabrication. If you want to order PCB product, please check and custom your order online. Single-Sided PCB Fabrication Process:Single-sided copper-clad board --> Cutting --> (Etching, Drying) --> Drilling or Punching --> Screen printing of circuit resist pattern or using dry film -> Curing, Inspection, Repair --> Copper etching --> Removal of resist, Drying --> Etching of resist pattern --> Screen printing of solder mask pattern (usually green) with UV curing --> Screen printing of component markings, UV curing --> Preheating, Punching and profiling --> Electrical continuity and short circuit testing --> Cleaning, Drying --> Precoating with solder flux and anti-oxidation agent (Drying) or Hot air solder leveling (HASL) --> Inspection, Packaging --> Final product delivery Double-Sided PCB Fabrication Process:Double-sided copper-clad board --> Cutting --> Lamination -> CNC drilling of through-holes --> Inspection, Deburring, Cleaning -> Chemical copper plating (through-hole metallization) -> (Full-board copper electroplating) -> Inspection, Cleaning -> Screen printing of negative circuit pattern, curing (dry film or wet film, exposure, development) -> Inspection, Repair --> Electroplating of circuit pattern --> Tin plating (nickel/gold for corrosion resistance) -> Removal of ink (photoresist) -> Copper etching -> (Desoldering) -> Cleaning -> Screen printing of solder mask pattern, typically thermosetting green mask (applying photoresist or dry film, exposure, development, thermosetting) -> Cleaning, Drying -> Screen printing of component markings, curing --> (Tin spraying or applying organic solderability preservatives) -> Profiling -> Cleaning -> Electrical continuity and insulation testing -> Inspection, Packaging -> Final product delivery Multi-Layer PCB Fabrication Process (Using Through-Hole Plating):Manufacturing process for multi-layer boards using through-hole plating --> Inner layer copper-clad board, double-sided profiling -> Cleaning -> Drilling for hole positioning -> Applying photosensitive etch-resistant dry film or coating with photosensitive etch-resistant agent -> Exposure -> Development -> Etching and resist removal -> Inner layer roughening, deoxidation -> Inner layer inspection -> (Outer layer single-sided copper-clad board circuit fabrication, B-stage bonding sheet, material bonding sheet inspection, hole positioning) -> Lamination -> CNC drilling -> Hole inspection -> Pre-treatment and electroless copper plating -> Full-board copper plating -> Plating inspection -> Applying photosensitive electroplatable dry film or coating with photosensitive electroplatable agent -> Exposure of outer layer base board -> Development, Repair -> Electroplating of circuit pattern -> Electroplating of tin-lead alloy or nickel/gold -> Removal of resist and etching -> Inspection -> Screen printing of solder mask pattern or photosensitive solder mask pattern -> Printing of character patterns -> (Hot air solder leveling or applying organic solderability preservatives) -> CNC profiling -> Cleaning -> Electrical continuity and disconnection testing -> Inspection, Packaging -> Final product delivery.PCBBUY Process in here:https://www.pcbbuy.com/pcb_manufacturing_process.htmlwhat is a single sided pcb?A single-sided printed circuit board (PCB) is a type of circuit board primarily produced through the direct etching of copper foil. It emerged in the early 1950s with the United States as a central hub for its development. This type of PCB is characterized by its high wiring density, lightweight, thin thickness, and good flexibility. These advantages have led to the widespread use of single-sided PCBs in electronic devices, especially those requiring lightness and good flexibility. With the advancement of transistors, single-sided PCBs rapidly gained popularity, becoming one of the mainstream products in the PCB manufacturing industry. Single-Sided Copper-Clad Board:A single-sided copper-clad board is a type of substrate where a layer of metal material, typically copper, is adhered to an insulating material according to specific requirements. It comes in two types: single-sided with a bottom layer and single-sided with a middle layer. This material is predominantly used for making PCBs. It features higher power voltage (8.5V) and lower signal voltage (1.5V). The product attributes include new and hot-selling items with thicknesses of 1.6mm and 2.0mm. This material is widely used in the PCB manufacturing industry due to its excellent conductivity and mechanical strength, meeting the requirements of various electronic devices. PCB Cutting:PCB cutting involves the process of resizing double-sided PCB sheets to the desired dimensions. Standard specifications typically employ PCB boards with a thickness of 1.6mm. Prior to cutting, necessary tools and materials like wooden boards, cardboard, marking pens, rulers, and cutting tools need to be prepared. During the cutting process, a wooden board is placed on the PCB board to be cut, and an outline is drawn along the wooden board using a marking pen. The cutting is then carried out along the drawn outline using a cutting tool. During the process, it's crucial to maintain the perpendicularity of the cutting surface to avoid injury. After cutting, the resulting PCB board should be inspected to ensure compliance with requirements. Inspection aspects include dimensions, labeling, and appearance. PCB boards that meet the criteria can proceed to the next processing steps, while those that don't need to be reworked or discarded. Therefore, precision and carefulness are essential during PCB cutting to ensure that each step meets requirements and the final PCB product quality conforms to standards. PCB Etching and Drying:PCB etching and drying are two critical steps in the PCB manufacturing process. Etching involves the use of specific cleaning agents such as chloride and fluoride solvents, as well as nylon or cloth brushes, to clean the surface of the PCB board from oxidation, dirt, and other impurities. The purpose of the cleaning agents is to remove dirt and impurities from the PCB surface, enhancing the board's conductivity and reliability. Following etching, drying is conducted to remove residual cleaning agents and moisture from the PCB board. Drying methods include natural air drying and hot air drying. Natural air drying entails placing the cleaned PCB board in a well-ventilated area to allow moisture to evaporate naturally. Hot air drying involves using high-temperature airflow through drying equipment to dry the PCB board. During drying, over-heating or extended heating should be avoided to prevent deformation or damage to the PCB board. Drilling or Punching:During PCB manufacturing, drilling or punching operations are performed to create holes that connect various conductive paths on the circuit board. Drilling involves creating small holes of the required dimensions on the PCB board's surface to interconnect various conductive paths. Drilling is executed using drilling machines or laser drilling equipment, following the precise hole placement as per the PCB design requirements. On the other hand, punching involves using punching machines to interconnect two conductive paths. Punching is performed on the PCB board's surface, necessitating accuracy to ensure high-quality interconnections. Whether drilling or punching, both processes are pivotal in PCB manufacturing and require precision and accuracy to ensure the board's quality and reliability. Screen Printing of Circuit Resist Pattern or Use of Dry Film:During PCB manufacturing, screen printing of circuit resist patterns or using dry film techniques are employed. Screen printing of circuit resist patterns involves using screen printing machines to apply resist ink onto the PCB's surface, forming the desired circuit patterns. This process requires specialized screen printing equipment and resist ink to ensure the accuracy and precision of the circuit patterns. Using dry film entails applying a thin film to the PCB surface to protect the circuit patterns from oxidation or corrosion. This step involves utilizing specialized dry film materials and equipment to ensure the quality and precision of the film coverage. Both of these steps are crucial in the PCB manufacturing process, requiring accurate operations to ensure the board's quality and reliability. PCB Curing, Inspection, and Repair:After PCB curing, an inspection process is carried out, and if any issues are detected on the PCB board, repair actions are undertaken. The repair process includes the following steps: Identifying issues: Inspect the cured PCB board and identify any problems, such as faulty connections or missing components.Preparing tools: Gather the necessary tools for repair, including blades, pads, solder, etc.Conducting repairs: Depending on the issues, use appropriate tools for repair. For instance, if there's a faulty connection, use a blade to cut the connection and then use pads and solder to establish a new connection.Testing the repaired PCB board: After completing the repair process, test the PCB board to ensure that the repairs have restored normal functionality.Repair operations require specialized skills and experience. Incorrect handling may lead to PCB board damage or malfunction. PCB Copper Etching:PCB copper etching involves chemically removing unwanted copper conductors from the surface of the copper-clad board to form circuit patterns. This process is achieved using acid solutions such as copper chloride with hydrochloric acid or copper chloride with ammonia solution. Parameters such as temperature, pressure, time, and solution concentration need to be controlled to ensure the etching process operates optimally. The predominant etching equipment is horizontal conveyor spray etching, which involves conveyor methods and spray methods. Removal of Resist and Drying:The removal of resist and drying in PCB manufacturing involves two key steps, outlined below: Removal of Resist: The process involves using chemical stripping or micro-etching methods to remove the resist applied to the PCB board's surface.Drying: After removing the resist, the PCB is placed in a drying chamber to eliminate excess solvents and volatile substances, ensuring that the coating dries and forms a stable protective layer.Both of these steps are integral to the PCB manufacturing process, requiring the selection of appropriate processes and equipment to ensure that the treated PCB board meets requirements. Screen Printing of Solder Mask Pattern (Often Using Green Ink):Screen printing of the solder mask pattern involves applying a layer of solder mask material to the surface of the PCB. This solder mask, often green in color, is used to protect the exposed copper traces and components from oxidation and other environmental factors. The screen printing process utilizes specialized equipment to accurately apply the solder mask material in the desired pattern. UV Curing:UV curing refers to a process where specific materials, such as the solder mask or other coatings on the PCB, are exposed to ultraviolet (UV) light. This exposure triggers a chemical reaction that results in the formation of a stable polymer. UV curing is fast, efficient, and environmentally friendly, making it a widely used method in PCB manufacturing. Screen Printing of Component Markings:Screen printing of component markings involves applying markings, labels, or symbols onto the surface of the PCB to indicate the placement and identification of components. This step is essential for ensuring proper assembly and maintenance of the PCB. PCB Preheating, Punching, and Profiling:PCB preheating, punching, and profiling are three steps in the PCB manufacturing process: PCB Preheating: Preheating is crucial in the PCB manufacturing process. It helps relieve internal stress and deformations within the PCB, enhancing its stability and reliability.Punching: Punching involves using a punching machine to create holes in the PCB. The precision and quality of punching directly impact the overall quality and performance of the PCB.Profiling: Profiling includes cutting, bending, and shaping operations to achieve the desired external shape of the PCB. The accuracy and quality of profiling affect the final quality and performance of the PCB. PCB Electrical Continuity and Short Circuit Testing:Electrical continuity and short circuit testing are conducted to ensure that the circuit connections on the PCB are correct and free from any short circuits that could lead to malfunctions or failures. These tests are essential for guaranteeing the PCB's functionality and reliability. what is a double sided pcb?A double-sided copper-clad board is a type of PCB where two conductive circuit boards are sandwiched with an insulating material in between. Copper foils are then pressed onto both sides, allowing both sides to be used as circuits. Double-sided copper-clad boards are a type of double-layered board and are widely used in PCB manufacturing. This material is commonly used in computer motherboards, where copper is laid on the substrate of the motherboard, and then it is divided into multiple independent units using specific patterns. Circuits are created within each unit, ultimately completing the fabrication of a double-sided circuit board. Layer Stacking:Layer stacking is a step in the PCB manufacturing process where multiple layers of PCBs are stacked in a specific order. In the PCB manufacturing process, layer stacking involves placing multiple layers that need to be laminated in the correct sequence. It is achieved through the process of brownization (also known as blackening), where the PCB, confirmed after inspection, is treated with brownizing solution to create a fuzzy copper surface. This increases roughness and forms an organic oxide layer on the surface, enhancing the contact surface area with the resin and ensuring reliable lamination. CNC Drilling for Through-Holes:CNC drilling for through-holes is a machining process aimed at drilling conductive through-holes on the PCB substrate. Here's the basic process: Mount the drill bit on the CNC drilling machine and place the PCB substrate on the worktable.Determine the positions and sizes of the through-holes.Adjust the drill bit's position and height to align with the through-hole locations.Start the CNC drilling machine to perform the drilling operation.After completing the drilling of through-holes, remove the PCB substrate from the CNC drilling machine. Regularly check the drill bit for wear and replace it if necessary. PCB Deburring and Cleaning:The method for PCB deburring and cleaning is as follows: Manual wiping: Wipe the PCB board using a brush soaked in alcohol or a lint-free cloth. Alternatively, specialized SMT wiping paper can be used to clean the PCB and remove cured solder paste or adhesive. While this method is convenient and cost-effective, it has several drawbacks such as inefficient cleaning, wastage of labor, and the potential for chemical solvents to violate environmental regulations.Equipment cleaning: Add an appropriate amount of cleaning solution, set the cleaning time, machine parameters, and drying time. Place the PCB board on the fixture inside the machine, then start the equipment to perform the cleaning. This method is safe, environmentally friendly, cost-effective (as the cleaning solution can be recycled), and offers high cleanliness up to 99.8%. It ensures thorough cleaning and drying. Chemical Plating (Through-Hole, Electroless Nickel/Gold):Chemical plating involves depositing a metal onto a substrate's surface using specialized plating solutions. Electroless nickel/gold plating is used for through-hole metalization in PCBs. This process deposits metal inside and on the surface of through-holes using chemical reactions, allowing for the connection of different layers of the PCB. This process is also known as hole metallization. While chemical plating offers advantages like coating non-conductive substrates and achieving strong adhesion, it can be costly due to the price of chemicals used. Full-Panel Electroplating of Thin Copper:Full-panel electroplating of thin copper involves depositing a layer of copper onto the entire surface of a PCB to protect the deposited thin copper, preventing its oxidation from being eroded by acid. Simultaneously, the deposited layer is thickened to a certain extent through electroplating. The process for full-panel electroplating of thin copper is as follows: Grinding the board.Pre-immersion.Full-panel electroplating of thin copper.Rinsing.Drying.Descending the tank.Rinsing.Drying.Inspection. Screen Printing Solder Mask Pattern (Often Using Green Ink):Screen printing of the solder mask pattern involves applying a layer of solder mask material to the PCB's surface. This solder mask, often green in color, is used to protect the exposed copper traces and components from oxidation and other environmental factors. The screen printing process uses specialized equipment to accurately apply the solder mask material in the desired pattern. UV Curing:UV curing refers to the process of exposing specific materials, such as solder mask or other coatings on the PCB, to ultraviolet (UV) light. This exposure triggers a chemical reaction that leads to the formation of a stable polymer. UV curing is rapid, efficient, and environmentally friendly, making it widely used in PCB manufacturing. Screen Printing Component Markings:Screen printing component markings involve applying labels, symbols, or identification codes to the surface of the PCB to indicate the placement and identification of components. This step is crucial for accurate assembly and maintenance of the PCB. PCB Preheating, Punching, and Profiling:PCB preheating, punching, and profiling are essential steps in the PCB manufacturing process: PCB Preheating: Preheating relieves internal stress and deformations in the PCB, enhancing its stability and reliability.Punching: Punching involves using a punching machine to create holes in the PCB. The quality of punching directly affects the overall performance of the PCB.Profiling: Profiling includes cutting, bending, and shaping to achieve the desired external shape of the PCB. Accurate profiling is crucial for the final quality and performance of the PCB. PCB Electrical Continuity and Short Circuit Testing:Electrical continuity and short circuit testing ensure that the circuit connections on the PCB are correct and free from short circuits that could lead to malfunctions or failures. These tests are vital to ensuring the functionality and reliability of the PCB. what is a multilayer pcb?A multilayer printed circuit board (PCB) is a type of circuit board used in electronic products that consists of multiple layers of insulation substrate with interconnected traces and solder pads for mounting electronic components. It serves the purpose of conducting signals across different layers while also providing insulation between them. Inner Layer Copper CladdingInner layer copper cladding refers to the addition of inner layers to a double-sided copper-clad PCB. Inner layer copper cladding allows for precise control of the thickness of inner layer PCB copper foils and control of controlled impedance for signal transmission. This can effectively enhance the quality of transmission for high-speed digital and high-frequency RF signals. Double-Sided Routing for Inner Layer Copper CladdingDouble-sided routing for inner layer copper cladding involves precision machining of the inner layer copper-clad PCB to create openings on both sides, facilitating further processing and manufacturing. Inner layer copper cladding is mainly used for connecting, securing, and testing electronic components. It can also provide functions such as electromagnetic shielding and heat dissipation. Drill Hole PositioningDrilling is carried out using a drill press, and the steps include: Preparing tools, including a drill press, fixture, center drill, etc.Installing the fixture and adjusting its position to align with the drill press spindle.Preparing the center drill and adjusting its protrusion length in the drill chuck.Fixing the fixture to the drill press spindle.Adjusting the drill press speed, running without load to check for smooth rotation.Placing the center drill on the surface of the workpiece.Starting the drill press and drilling holes according to the fixture's hole positioning.Upon reaching the desired depth, retracting the drill bit.Cleaning up the debris. Applying Photosensitive Anti-Corrosion Dry Film or Coating Photosensitive Anti-Corrosion AgentPhotosensitive anti-corrosion dry film or coating photosensitive anti-corrosion agent is used during the PCB fabrication process for corrosion resistance. Photosensitive anti-corrosion dry film is applied on a PET film, and after exposure to ultraviolet light, the exposed areas are dissolved using a developing solution. The remaining resin in the unexposed areas is retained, and the unexposed copper layer is removed through etching, forming the desired pattern. Coating photosensitive anti-corrosion agent involves applying a layer of such agent, followed by a layer of resin, and then curing it with UV light. PCB ExposurePCB exposure involves placing various materials that need exposure under sunlight or ultraviolet light to evenly project their images onto photosensitive material, creating a photosensitive, developing, or imaging effect. Exposure in PCB fabrication refers to using UV radiation to expose the resist areas of the PCB after silk screening. The exposed areas undergo a polymerization reaction. Subsequently, during the development process, the unexposed resist is removed using a developing solution, leaving behind the polymerized areas, creating the required solder mask pattern on the PCB. PCB DevelopmentDevelopment in PCB fabrication refers to the process of using chemicals, typically alkaline developer, to remove the unexposed resist material from the PCB surface. The alkaline developer dissolves the chemicals in the unexposed areas of the photosensitive film, exposing the underlying copper layer. Different types of developers are used based on the type of photosensitive film used. Etching and StrippingEtching and stripping are two different processes with distinct purposes and applications: Etching: After exposure and development, the protective film is removed from the areas that need to be etched. The board is then subjected to a chemical solution that dissolves the exposed copper areas, resulting in the formation of desired patterns.Stripping: During development, the chemical solution removes the protective film from the unexposed or inadequately exposed areas that are not supposed to be etched. Inner Layer Processing and Oxide RemovalInner layer processing involves increasing the roughness of inner layer traces after edge grinding to enhance adhesion between dry film and the substrate. Oxide removal is performed on the copper surface of inner layer traces after they are completed, aiming to improve solderability and copper plating quality. Inner Layer InspectionInner layer inspection includes: Verifying correct layer definitions.Checking that inner layer routing compensation matches the data.Ensuring independent pads on inner layer traces are properly removed.Checking for added teardrops on pads with line widths smaller than 24 mils.Inspecting via hole clearance and minimum distance from the edge.Verifying the correctness of markings on inner layer films.Inspection of Outer Layer Copper Cladding, B-stage bonding sheets, and bonding sheet material, and drilling positioning holes. Lamination Lamination is a process used to create multi-layered printed circuit boards (PCBs). Before lamination, the inner layers of the PCB undergo extreme temperatures and pressure. Then, a photosensitive dry film resist is laminated onto the surface, followed by curing at high temperatures. Finally, pressure is slowly released, and the laminated material is gradually cooled. Numerical Control Drilling The steps involved in numerical control drilling are as follows: Line Marking: Use tools to mark the centerline of hole positions according to the basic drilling standard requirements. The centerline should be clear and accurate. Measure the marked lines using calipers or steel rulers.Grid or Circular Marking: After marking lines and verifying their accuracy, create a grid or circle centered on the hole centerline. This serves as a reference for checking and correcting hole positioning during drilling.Punching a Sample Hole: Start by punching a small point on the cross centerline in different directions. This helps ensure that the punched hole is precisely located at the intersection of the cross centerlines. Gradually enlarge the sample hole to achieve accurate alignment.Clamping: Clean the machine table, fixture surface, and workpiece reference surface with a cloth. Then securely clamp the workpiece, ensuring it is flat, firm, and easy to inspect and measure. Pay attention to the clamping method to prevent workpiece deformation.Trial Drilling: Before drilling the actual holes, conduct trial drilling. Align the drill bit with the center of the hole and drill a shallow pit at the location of the sample punched hole. Visually inspect the alignment of the pit and make necessary adjustments to achieve coaxial alignment. Hole Inspection Hole inspection refers to the measurement of positional tolerance for each hole in a given product before the manufacturing process. It's a method of controlling the production process to ensure that all hole dimensions, shapes, and relative positions meet the required specifications. The steps of hole inspection include: Line Marking: Use tools to mark the centerline of hole positions. The centerline should be clear and accurate. Measure the marked lines using calipers or steel rulers.Grid or Circular Marking: After marking lines and verifying their accuracy, create a grid or circle centered on the hole centerline. This serves as a reference for checking and correcting hole positioning during drilling.Punching a Sample Hole: Start by punching a small point on the cross centerline in different directions. This helps ensure that the punched hole is precisely located at the intersection of the cross centerlines. Gradually enlarge the sample hole to achieve accurate alignment.Clamping: Clean the machine table, fixture surface, and workpiece reference surface with a cloth. Then securely clamp the workpiece, ensuring it is flat, firm, and easy to inspect and measure. Pay attention to the clamping method to prevent workpiece deformation.Trial Drilling: Before drilling the actual holes, conduct trial drilling. Align the drill bit with the center of the hole and drill a shallow pit at the location of the sample punched hole. Visually inspect the alignment of the pit and make necessary adjustments to achieve coaxial alignment. Pre-Treatment and Electroless Copper Plating for Holes Pre-treatment before electroless copper plating is an important step to enhance the adhesion between the substrate and the copper layer. The process includes the following steps: drilling, alkaline cleaning, water rinsing, acid etching, water rinsing, activation, water rinsing, acceleration, water rinsing, and electroless copper plating. Full Panel Electroplating of Thin Copper Parameters for full panel electroplating of thin copper include: Bath Composition: The main components are copper sulfate and sulfuric acid. A high acid to low copper formula is used to ensure even thickness distribution on the plated surface and the ability to plate deep holes and small holes effectively.Sulfuric Acid Concentration: Typically around 180 g/L, sometimes up to 240 g/L. Copper sulfate concentration is generally around 75 g/L. A small amount of chloride ions is added to the bath as auxiliary brighteners and leveling agents for enhancing the gloss effect.Copper Brightener: The addition or replenishment of copper brightener is generally done at a rate of 3-5 ml/L or according to ampere-hour method based on actual production requirements.Current Calculation: The current for full panel electroplating is usually calculated as 2 A/dm² multiplied by the plated surface area on the board. PCB Plating Inspection Methods for inspecting PCB plating include: Chemical Element Analysis with XRF: Using X-ray fluorescence (XRF) equipment to perform chemical element analysis on PCB materials, including pure copper foil, substrate, etc. This ensures the quality meets required standards and production specifications.Thickness Measurement with XRF Thickness Gauge: Rapid and accurate measurement of thickness for various materials and plated layers on the PCB, such as gold, silver, tin, etc. This ensures proper adhesion of the plating and correct signal transmission.Impurity Detection with XRF Thickness Gauge: Detecting impurities on the PCB surface to exclude defective products and improve production efficiency. Applying Photosensitive Electroplatable Dry Film or Electroplatable Resistant Film The steps for applying photosensitive electroplatable dry film or electroplatable resistant film are as follows: Line Marking: Use tools to mark the centerline of hole positions according to the basic drilling standard requirements. The centerline should be clear and accurate. Measure the marked lines using calipers or steel rulers.Grid or Circular Marking: After marking lines and verifying their accuracy, create a grid or circle centered on the hole centerline. This serves as a reference for checking and correcting hole positioning during drilling.Punching a Sample Hole: Start by punching a small point on the cross centerline in different directions. This helps ensure that the punched hole is precisely located at the intersection of the cross centerlines. Gradually enlarge the sample hole to achieve accurate alignment.Clamping: Clean the machine table, fixture surface, and workpiece reference surface with a cloth. Then securely clamp the workpiece, ensuring it is flat, firm, and easy to inspect and measure. Pay attention to the clamping method to prevent workpiece deformation.Trial Drilling: Before drilling the actual holes, conduct trial drilling. Align the drill bit with the center of the hole and drill a shallow pit at the location of the sample punched hole. Visually inspect the alignment of the pit and make necessary adjustments to achieve coaxial alignment.PCB Surface Layer Exposure PCB surface layer exposure is an important step in the PCB production process. Exposure involves using ultraviolet (UV) light to cure the solder mask on the PCB. Here's how the process works: The PCB with the developed solder mask is placed on the film master.Ultraviolet light is directed through the film master, which has transparent areas that correspond to the solder mask openings.The UV light triggers a chemical reaction in the solder mask material, causing it to harden or cure.After exposure, the unexposed areas of the solder mask are washed away using a developer solution.The hardened areas of the solder mask remain on the PCB surface, protecting the copper traces and components during subsequent processes like soldering and assembly. This process ensures that the solder mask adheres to the desired areas, preventing solder bridges and ensuring proper component placement and soldering during PCB assembly. The quality of exposure affects the accuracy of the solder mask pattern and the overall reliability of the PCB.