PCB Manufacturing Process: From Design to Production

Have you ever thought about the process through which the electronic devices you use daily are manufactured? It is simple.

If you have some designs that need to be converted into good PCBs, then we at PCBMay are right here for you. We take your hand as we walk from design to production ensuring the perfection of your devices.

What are the PCBs?

The cores of most electronic devices are the printed circuit boards (PCBs), which link and support a variety of electronic components. 

Nowadays, these are made from diverse materials but predominantly fiberglass with complex copper lines that join such elements as resistors, capacitors, and microchips.

Is it Important to Understand the PCB Manufacturing Process?

Yes, this is very important. Before understanding the circuit board, you need to understand its production process.

Because there are many processes involved, you need to have a deep understanding of each process.

How is A PCB Manufactured?

Here we’ll guide you through the whole 20 steps in PCB manufacturing with detailed explanations and examples.

Step 1: Design the PCB 

Using special software like Eagle, Altium Designer, or KiCad, designing the PCB layout will be done. Here you will find a detailed list of software. 

What these tools do is they enable you to make a schematic. The design stage involves component placement definition, electrical connections routing, and defining layer stack-up. 

When developing such layouts it must meet specific design rules of the manufacturing process; this includes spacing, trace width, and component tolerances.

For example, if you are creating a high-frequency PCB for telecommunication then while designing; signal integrity as well as electromagnetic interference (EMI) are some aspects that should be taken into account. 

It is vital to have good grounding and shielding so as not to lose signal strength or get disturbed by noise. Besides, designers usually perform simulations beforehand to verify if the board will work properly after production.

Step 2: Design Review and Engineering Questions

After doing an initial design, there is a complete review carried out where engineers check whether there are any potential problems regarding the components’ positioning or even route materials, etc., 

This review often incorporates a Design for Manufacturability (DFM) check which ensures that the PCB can be reliably manufactured at an affordable cost.

For instance, the distance for the solder mask is too small, and could not make the solder bridge, so the manufacturer has to check with the customers first. 

By addressing such issues early on you will avoid costly rework and delays in production. At times it could involve talking with your PCB manufacturer at this stage so that all doubts can be cleared up when necessary amendments are made.

PCB Design Review

PCB Design Review

Step 3: Printing the PCB Design

An outline plotter printer is used to print out the design, which will be printed on a transparent film. 

Each of these films acts as a photographic negative for one layer in the PCB. For a simple double-sided board, you’ll need six films, one each for both layers, one each for both solder masks, one each for both silkscreens

These films are then registered with holes made through them. This ensures that every layer of PCB will be accurately aligned during the manufacturing process. 

Alignment accuracy is important notably for multilayer PCB since without it there could be electrical shorts or open circuits due to misalignment.

Step 4: Printing the Copper for the Interior Layer 

After that, the design is transferred onto a laminate that is covered with copper. 

On top of the laminate lies a photosensitive layer known as photoresist. 

Next, the printed film exposes the laminate to ultraviolet light, which hardens the photoresist in the PCB layout. 

The uncured places are washed off hence uncovering copper underneath.

This procedure is just like making a photograph. 

It is important because it forms the basis of PCB’s electrical pathways. A hardened photoresist covers desired circuit patterns formed by copper whereas an exposed one remains ready for etching.

Step 5: Etch the Inner Layers to Remove the Copper

In this step, unwanted copper from PCB undergoes chemical etching where it is removed. 

Submerging the board in a chemical solution removes any exposed copper, leaving behind just the photoresist-covered remnants.

For example, ferric chloride which is a typical etching solution can be used. However, there are situations where heavier boards may require stronger solutions or longer exposure times so as to remove all surplus copper. 

After removing regions not covered with photoresist through the etching process, engraving will leave patterns of coppers visible to the human eye. Precise etchings assure accurate replication of fine designs onto boards.

Step 6: Layer Alignment

Layer alignment is another important step after the inner layers have been etched and cleaned. 

Misalignment at this stage can lead to electrical shorts or open circuits, which can render the PCB useless.

Manufacturers achieve precise alignment by using registration holes that were previously punched into the layers. 

These holes serve as guides for stacking the layers properly. An optical punch machine places them on top of each other, ensuring that every single one lines up correctly with the others using a laser beam. 

To ensure this alignment, the machine punches more registration holes in the stack.

In applications like aerospace and medical devices where high precision is required, even a slight misalignment may result in significant problems. 

For example, X-ray alignment systems can be used to achieve greater precision than these ones. They give accurate feedback and adjustment as such making sure that they are accurately aligned​. 

Step 7: Automated Optical Inspection

An Automated Optical Inspection (AOI) is performed after aligning layers. AOI is a crucial stage in PCB manufacturing that detects imperfections on internal layers before being laminated together with other layers. 

This step is necessary because once laminated; any defects within get irredeemable.

High-resolution cameras and advanced software are employed by AOI systems for scanning through PCBs’ different sections. 

Scanned images obtained from AOI systems are compared against original design data (Gerber files) to detect variance in tracks misaligned traces, or short/open circuits respectively among others. 

Technicians then review and address potential issues highlighted by the AOI system.

AOI Testing Room

AOI Testing Room

Step 8: Laminating the PCB Layers

To make a multilayer PCB, the inner layers are bonded together with the outer layers in laminating the PCB layers. 

This process uses heat and pressure to fuse the layers together using a material called prepreg which acts as an adhesive.

These are stacked up in a particular order starting with a layer of prepreg and then followed by an etched inner layer then another layer of prepreg and finally, the outer copper layers. 

When lamination is to take place, the stack is heated and compressed in a press. 

When heated, the prepreg resin flows and solidifies, enclosing the layers.

The purpose of this procedure is to bind the various sheets together but at the same time ensure that there is some mechanical stability in the printed circuit board (PCB). 

Proper lamination is critical for maintaining the structural integrity of such boards especially where they will be exposed to different environmental conditions or subjected to mechanical stress​.

Step 9: Drilling

Drilling is a very vital step that involves making holes for vias (connections between different layers) and through holes. The position of the holes is important as it ensures proper electrical connectivity.

High-tech drilling machines are handy here. 

These machines operate at high speeds, typically over 100,000 RPM to drill holes that can be as small as 100 microns in diameter. 

For example, microvias are drilled into high-density interconnect (HDI) PCBs using laser technology to achieve the required precision.

An X-ray machine is used before drilling to accurately locate and mark drill targets. This helps in ensuring that the drill will hit the correct spots on the multilayer stack. 

Following this process, deburring and besmearing processes are carried out which remove burrs from drilled holes and smear any micro-fracture sites present on the board surface preparing them for plating.

Step 10: PCB Plating

After drilling comes PCB plating; it entails a thin coating of walls of drilled holes and a copper layer on top of PCB surfaces. 

This process which is referred to as electroless copper plating enables electric connection between different layers within the PCB.

Firstly, contaminants in it are removed by cleaning PCB so that they do not interfere with the plating process. 

Then this circuit board enters a series of chemical baths one after another where an essential bath is an electroless copper solution depositing a thin copper layer onto exposed surfaces such as walls of drilled holes whose thickness ranges from about 10-30 μm depending upon different requirements of the customers.

The layering of copper ensures reliable electrical connections between layers such that signals can traverse through without loss for instance in multilayer boards designed for smartphones, the copper-plated vias. 

This is followed by electroplating whereby an additional layer of copper is applied to achieve the desired thickness and improve the device’s life

Step 11: Outer Layer Imaging

After drilling and plating the outer layers, the next step is imaging the outer layers on the PCB. It’s a similar method used for imaging inner layers but concentrating on exterior circuits. 

In addition, a coat of photoresist is put over the external surfaces of the board. The light-sensitive material known as photoresist will be used in transferring circuit design onto copper layers.

Next, you expose that film to UV light such that it shines through a film carrying designs for this outer layer. 

The photoresist becomes hardened by the light in patterns forming circuits that shield underlying copper that eventually makes up final traces. 

The soft portions of the unexposed photoresist are washed off later to expose copper beneath them. This stage is important in creating accurate and repeatable circuit patterns that provide the functionality of a PCB​

Outer Layer Imaging

Outer Layer Imaging

Step 12: Outer Layer Etching

After the completion of the outer layer imaging, the next task is to etch the exposed copper. 

The printed circuit board is immersed in a chemical bath which eliminates all unprotected copper but leaves only desired circuit traces under cured photoresist. This process is important because it defines the outer pattern of circuits that will connect with other layers and components.

Different PCBs may call for various etching processes. 

For example, thicker copper layers or complex designs may require more time of exposure or stronger etchants to ensure that all unwanted copper is removed from them. 

After etching, one can remove the remaining photoresist leaving behind well-defined tracks on the PCB essential for electrical paths

Step 13: Outer Layer AOI

After etching through the outer layers, there is another Automated Optical Inspection (AOI) for the outer layer to ensure that no defects are found in newly created connections. 

​High-resolution scanning by cameras and comparing it with original design files helps identify such anomalies as shorts, open circuits, or misaligned traces.

This stage matters a lot because, when errors occur on these outer layers then they interfere with the performance of the PCB greatly. 

Detecting these issues early allows you to be confident about durability and prevent expensive reworks or failures during the final production stages. In case of any faults, they have to be corrected first before proceeding to the next phase.

Step 14: Solder Mask

In carrying out the manufacturing process for PCBs, solder mask application is always undertaken after completing this initial stage. 

Solder masks are applied by coating the PCBs with either liquid epoxy or dry film. After that, the printed circuit board is exposed to UV light through a mask to define the areas that require protection. 

The unexposed parts are then removed by washing and solder masks are left only on required areas. Generally, this solder mask is green but depending on your needs you can use other colors such as black, white, blue, or red.

Step 15: Silkscreen

The silkscreen process is a method in which text and symbols are printed onto the PCB to give it the necessary information about how components should be placed, their part numbers, logos, and other signs. This layer helps in troubleshooting as well as repair and also guides through the assembly process.

You can apply the silkscreen layer using screen printing or an inkjet printer. The ink is only applied to specific areas so that clear and readable markings are achieved. 

This step will provide a touch of professionalism on your PCBs, thus ensuring accurate assembly in cost-effective ways. 

Clear silk-screen marking is particularly important for complex PCBs used in industries such as telecommunications or medical devices where component placement must be precise.

Step 16: Surface Finish

Finishing up the printed circuit board with a surface treatment is the next step before testing. The finish has a dual impact. 

It prevents oxidation of exposed copper traces and guarantees optimum solderability. The benefits and uses for various surface treatments are diverse.

A few common finishes are Organic Solderability Preservative (OSP), Hot Air Solder Leveling (HASL), and Electroless Nickel Immersion Gold (ENIG).

For example, ENIG has excellent surface planarity making it ideal for fine-pitch components and soldering while HASL is cost-effective and provides good solderability for standard applications.

Which types of finishing you will use depends on many factors – not to mention pricing is one of the most important. 

The right finish shall ensure your PCB’s reliable performance when put into its intended use.

Step 17: Electrical Test

Electrical testing is a critical step in the manufacturing process of printed circuit boards because it helps verify electrical connectivity across circuits along with their integrity thereby ensuring that this board works accordingly. Two main electric tests exist: the flying probe test and the fixture test.

Flying Probe Test: It uses probes to contact the PCB pads and traces, checking for continuity and ensuring there are no short circuits. 

This method is flexible and cost-effective for small batches or prototypes while bed-of-nail testers are more appropriate for large production runs as it enables faster and more comprehensive testing of multiple points in a PCB.

Fixture test: It is mainly suitable for large quantities or mass production. All test points are connected through leads and tested at one time. 

This way, the test speed is fast and the efficiency is high. Moreover, one test fixture can be used many times, which can greatly reduce costs.

Step 18: Profiling and Route Out

Profiling, also known as routing or depanelization, refers to the cutting of manufactured PCBs into their final shape and size. 

This step involves breaking up individual PCBs from a production panel with multiple boards for maximal process efficiency.

There are different methods used in profiling, such as CNC routing, laser cutting, or V-scoring.

The precision of this method is extreme and it is ideal for complex shapes and designs. On the other hand, Laser Cutting has even more accuracy and it’s perfect for complicated patterns that require high tolerances. 

However, it is usually more expensive than CNC routing. 

The process referred to as V-Scoring results in V-shaped cracks on the surface of the board which allows one to physically break them apart by hand. 

For straight separations along a straight line, this method is most cost effective but it is not suitable for complex shapes.

The choice of profiling method depends on PCB design, production volume, and cost considerations.

Step 19: Quality Check and Visual Inspection

There is a thorough quality check and visual inspection before the PCBs are shipped, to ensure they meet all specifications and standards. This step combines automatic and manual checks in order to detect any remaining faults or abnormalities.

For example, the automatic board inspection machine, as long as the circuit board is placed on the machine, it will quickly identify solder mask scratches, whether the mark is missing, open circuit, etc.

Meanwhile, Manual Inspection serves as a companion measure by allowing expert personnel to go through the PCBs for anything that may slip past automated systems. The technicians are looking at solder joint quality, and component placement, among other optical discrepancies. They also perform functional tests on them to ascertain if they can work well under real-world conditions.

Combining automated with manual inspections ensures manufacturers will be able to reach out to their highest quality standards

PCB Inspection

PCB Inspection

Step 20: Packaging and Delivery

The ultimate stage in PCB manufacturing is about packaging and delivery. Good packaging is necessary to prevent damage to the PCBs during transportation and handling.

Such PCBs should be enclosed in anti-static materials to avoid electrostatic discharge (ESD) which may spoil sensitive components. Some of them can also be vacuum-sealed to protect against moisture or environmental contaminants.

 Additionally, they can be packed in cushioned packaging or hard containers for extra protection from physical damage.

Labeling and documentation are part of the packaging process. Every package has appropriate information such as part number, lot number, customer details, etc. 

Additional paperwork could include test reports, certificates of compliance, and other documents that ensure traceability and quality control.

When the PCBs are adequately packaged, they are transported to the customers via reliable logistic services. 

FAQ

What is the Importance of Inspection and Testing in PCB Manufacturing?

Inspection and testing are done to ensure that the printed circuit board meets specifications as well as functions properly. It reduces defects’ risks, enhances product reliability, and improves yields

What are Some of the Environmental Considerations in PCB Manufacturing?

Environmental concerns include waste management; energy reduction, minimizing toxic chemical use to avoid pollution, and promoting sustainability

What is Sustainable Manufacturing in the Context of PCB Production?

Use of eco-friendly materials, waste minimization, recycling, and optimization of energy use for minimal environmental impact toward long-term viability

What are Some of the Quality Control Standards in PCB Manufacturing?

Quality control standards comprise ISO 9001 for quality management systems; IPC standards for printed circuit board production and UL certification of safety & performance. 

Why Choose PCBMay for Your PCB Manufacturing Needs?

PCBMay is a go-to PCB manufacturer for many clients in different industries.  

It is always our concern to ensure that every step, starting from design to delivery meets the best practices in the industry due to our modern technology. 

Our dedication to perfection and customer contentment makes us stand out from other companies. We rest right next to you as we strive to offer you dependable and cheap solutions. 

If you need your PCB then think PCBMay and see how quality differs from service. Send us a message.

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