1. The Foundation: Design and Output

The first step in creating a PCB is all about design and output. This is where the magic begins! Circuit designers use special software to create a layout for the PCB. Think of it like an architect using blueprints to design a building. Some commonly used software includes Altium Designer, OrCAD, Pads, KiCad, and Eagle.

Before starting the design, it’s a great idea for designers to visit a PCB manufacturing shop. This helps them understand the manufacturing process better and communicate their needs directly with the fabricators. However, these days, many companies outsource their manufacturing to overseas suppliers, so this isn’t always possible.

Once the design is complete, it’s time to export it. Designers need to make sure they use a format that the manufacturer can work with. The most common format is called extended Gerber, also known as IX274X. It’s like sending a letter in the right envelope so it can be delivered correctly.

The Gerber file contains all the important information about the PCB design, such as the copper tracking layers, drill drawing, apertures, and component notations. It’s like a detailed map that the manufacturer will follow to create the PCB.

Before sending the file to the manufacturer, designers should double – check everything. They need to make sure the track width, board edge spacing, trace and hole spacing, and hole size are all correct. It’s like proofreading a story to catch any mistakes before publishing it.

Almost all PCB fabricators will perform a Design for Manufacture (DFM) check. This ensures that the design can be made with the minimum tolerances during the manufacturing process. It’s like a quality check to make sure the final product will be just right.

2. From Digital to Physical: File to Film

Once the design is all set and the DFM check is done, it’s time to bring the digital design into the physical world. This is where the file – to – film stage comes in.

Manufacturers use a special printer called a plotter. It’s not your regular office printer. Think of it as a super – precise artist that can create highly detailed images. The plotter uses really accurate printing technology to make photo films of the PCBs. These films are like the blueprints in a more tangible form.

The final product is a plastic sheet with a photo negative of the PCB in black ink. For the inner layers of the PCB, the black ink represents the conductive copper parts. The clear parts are the non – conductive areas. It’s like a map where the black roads are the paths for electricity to flow.

For the outer layers, it’s the opposite. The clear parts are for the copper, and the black parts are the areas that will be etched away later. It’s a bit like a reverse coloring book!

Each layer of the PCB and the solder mask gets its own set of clear and black film sheets. For example, a two – layer PCB needs four sheets in total: two for the layers and two for the solder mask.

To make sure all these films line up perfectly, registration holes are punched through them. It’s like using holes in sheets of paper to align them in a binder. The table that holds the film is adjusted to ensure the holes are punched in the exact right place. These holes will fit onto registration pins in the next step of the imaging process, ensuring everything is in the correct position.

3. Inner Layer Printing: Mapping the Copper Path

Now that we have the films ready, it’s time to start printing the inner layers. This step is crucial as it determines where the copper will be placed on the PCB.

First, we need to prepare the substrate material. The basic form of a PCB is a laminate board made of epoxy resin and glass fiber, also known as the substrate. It’s like the base of a cake, providing a stable structure for the rest of the components. Copper is pre – bonded on both sides of the laminate.

Before we start the printing process, cleanliness is key. We clean the copper – sided laminate and move it into a decontaminated environment. We can’t have any dust particles settling on the laminate because even a tiny speck of dirt could cause a short circuit or an open circuit. It’s like making sure a kitchen countertop is clean before baking a cake to avoid any unwanted bits in the batter.

Next, we apply a layer of photo – sensitive film called photo resist to the clean panel. This photo resist is made up of photo – reactive chemicals that harden when exposed to ultraviolet (UV) light. It’s like a special paint that changes when it sees light.

We then place the films onto pins to hold them in place over the laminate panel. The films and the board are lined up, and then they are hit with a blast of UV light. The light passes through the clear parts of the film, hardening the photo resist on the copper underneath. The black ink on the film blocks the light from reaching the areas that we don’t want to harden.

After the exposure, we wash the board with an alkaline solution. This removes any photo resist that didn’t harden. Then, we give it a final pressure wash to get rid of anything else left on the surface and dry it. The result is a board with the resist covering the copper areas that we want to keep in the final product. A technician will then carefully examine the boards to make sure there are no errors in this stage. All the resist at this point indicates where the copper will be in the finished PCB. This step is mainly for boards with more than two layers. Simple two – layer boards can skip ahead to the drilling step.

4. Unwanted Copper Removal: Shaping the Circuit

Now that we have the inner layers printed with the resist in the right places, it’s time to remove the unwanted copper. This step is like trimming the excess dough from the edges of a cookie cutter to get the perfect – shaped cookie.

First, we use a chemical solution. Just like the alkaline solution removed the unhardened photo resist earlier, this time, a more powerful chemical preparation is used to eat away the excess copper. It’s like a hungry little cleaner that only eats the copper we don’t want. The copper solvent solution bath removes all of the exposed copper, while the copper that we want to keep is safely protected beneath the hardened layer of photo resist.

But here’s something to note: not all copper boards are the same. Some heavier boards might need more copper solvent and a different amount of time in the solution. It’s like cooking different – sized meals; you might need to adjust the cooking time and the amount of ingredients. Also, heavier copper boards need extra attention when it comes to track spacing.

Once the unwanted copper is removed, we need to get rid of the hardened resist that was protecting the good copper. Another solvent comes to the rescue. After this step, the board is left with only the copper substrate that’s necessary for the PCB. It’s starting to look more and more like a proper circuit board, with only the essential parts remaining!

5. Layer Alignment and Inspection: Ensuring Precision

After the unwanted copper is removed, we move on to the layer alignment and inspection stage. This is like making sure all the pieces of a puzzle fit together perfectly.

First, we need to align all the layers. The registration holes that we punched in the films earlier come in handy here. They help us align the inner layers with the outer layers. A technician places the layers into a special machine called an optical punch. This machine is like a super – precise aligner. It makes sure that the registration holes are punched accurately so that all the layers line up just right.

Once the layers are aligned, we can’t afford to have any errors on the inner layers because it’s impossible to fix them later. That’s why we use another machine for an automatic optical inspection (AOI). This machine is like a super – vigilant inspector. It uses a laser sensor to scan the layers and then electronically compares the digital image it captures with the original Gerber file that the manufacturer received.

If the AOI machine finds any differences between the scanned image and the Gerber file, it will display the comparison on a monitor. A technician will then carefully assess the situation. If everything checks out and the layer passes the inspection, it can move on to the final stages of PCB production. This step is crucial for ensuring the quality and functionality of the final PCB product.

6. Layer – up and Bond: Building the PCB Structure

Now, it’s time to start building the actual PCB structure. This is the layer – up and bond stage, where all the separate layers come together to form a single, functional PCB. It’s like building a sandwich, but instead of bread and fillings, we’re using layers of fiber glass, epoxy resin, and copper.

The outer layer material consists of sheets of fiber glass that are pre – impregnated with epoxy resin. We call this prepreg for short. There’s also a thin copper foil covering the top and bottom of the original substrate, which already has the copper trace etchings from the previous steps.

First, a technician places a prepreg layer over an alignment basin. Then, the substrate layer is carefully placed on top of the prepreg. After that, a copper sheet is added. More prepreg sheets are placed on top of the copper layer. Finally, an aluminum foil and a copper press plate are added to complete the stack. It’s like building a tower, but with very specific layers and materials.

The bonding process takes place on a heavy steel table with metal clamps. The layers are securely placed onto pins attached to the table to make sure everything fits tightly and doesn’t shift during the alignment. This is really important because any misalignment could affect the functionality of the final PCB.

Once everything is set up, a bonding press computer takes over. It controls the whole process, including heating up the stack to a specific temperature, applying the right amount of pressure at the right time, and then allowing the stack to cool down at a controlled rate. It’s like a chef following a very precise recipe to bake the perfect cake.

After the heating, pressing, and cooling are done, it’s time to unpack the PCB. The technician simply removes the restraining pins and gets rid of the top pressure plate. And there it is! The multi – layer PCB, all molded together, with the copper foil now forming the outer layers of the PCB. It’s starting to look like a proper circuit board, and we’re one step closer to having a fully functional PCB.

7. Drill: Creating the Connection Points

After the layers are bonded together, it’s time to drill holes in the PCB. These holes are like the doorways that will allow components to be connected to the PCB.

First, we use an x – ray locator. It’s like a super – precise map reader. This locator helps us find the exact spots where we need to drill the holes. It’s crucial to be very accurate at this stage because any small mistake could cause problems later on.

Once we know where to drill, we use a computer – controlled drill. The drill is like a super – fast and precise handyman. It can make holes with a diameter of about 100 microns, which is really small considering that an average human hair is about 150 microns in diameter.

Before we start drilling, we place a buffer material under the drill target. This buffer material is like a safety net. It helps to ensure that when the drill goes through the board, it doesn’t cause any tearing or damage to the bottom of the board.

The computer – driven machine uses the drilling file from the original design. It’s like the drill is following a set of instructions. It identifies the proper spots to bore, and the drills use air – driven spindles that can turn at an incredibly fast 150,000 revolutions per minute (rpm). But even with this high speed, it takes time because there are usually a lot of holes to drill. An average PCB has well over one hundred points where holes need to be drilled.

These holes are really important. They will later house things like vias, which are used to connect different layers of the PCB, and mechanical mounting holes that will hold components in place.

After all the holes are drilled, there’s usually some extra copper left on the edges of the production panel. We use a profiling tool to remove this excess copper. It’s like trimming the edges of a picture frame to make it look neat and tidy. Now our PCB is starting to look more like a proper circuit board, with all the necessary holes in place and the edges cleaned up!

8. Plating and Copper Deposition: Strengthening the Layers

After drilling all those holes, our PCB is now ready for the plating and copper deposition step. This is like adding a super – strong glue to hold all the layers together even better!

First, we give the panel a really good cleaning. It’s like giving a car a thorough wash before adding a new coat of paint. After the cleaning, the panel goes through a series of chemical baths.

During these baths, a chemical deposition process takes place. It’s like a magical little process where a thin layer of copper, about one micron thick, is deposited over the surface of the panel. But that’s not all! The copper also goes into the recently drilled holes.

Before this step, the inside of the holes was just the fiber glass material. Now, the copper baths completely cover the walls of the holes, or we can say they “plate” the holes. And the whole panel gets a new layer of copper too. This is really important because it helps to connect the different layers of the PCB and makes the electrical connections more reliable.

The entire process of dipping the panel in the chemical baths, removing it, and moving it along is controlled by computers. It’s like a computer – controlled dance, making sure every step is done perfectly. Now our PCB is getting even closer to being a fully – functional circuit board, with all the layers connected more securely by this new layer of copper!

9. Outer Layer Imaging: Designing the Exterior

Now, we’re on to the outer layer imaging step. This is like adding the final touches to a painting, making sure the outside of the PCB looks just right and functions as it should.

We start by working in a sterile room. It’s like a super – clean laboratory. This is really important because we want to prevent any contaminants from sticking to the layer surface. Contaminants could mess up the final product, just like a smudge on a clean window can make it hard to see through.

Once in the sterile room, we apply a layer of photo resist to the panel. Remember, photo resist is like a special material that changes when it sees light. It’s the key to getting the design onto the outer layers.

After applying the photo resist, the prepped panel is moved into a “yellow room.” You might be wondering why it’s called that. Well, UV lights can affect photo resist, but yellow light wavelengths don’t have enough UV to do that. It’s like a safe zone for the photo resist before we expose it to the right kind of light.

Next, we use black ink transparencies. These are secured by pins to prevent any misalignment with the panel. It’s like using clips to hold a stencil in place when you’re painting. With the panel and the stencil (the black ink transparency) in contact, a generator blasts them with high – intensity UV light. This hardens the photo resist in the areas where the light can pass through.

The panel then goes into a machine that removes the unhardened resist. The black ink on the transparency protects the areas where we don’t want the resist to be removed. It’s like a shield, blocking the removal process from certain parts.

This process is actually the opposite of what we did for the inner layers. And finally, the outer plates are carefully inspected. We need to make sure that all of the unwanted photo resist was removed during the previous stage. This inspection is crucial to ensure the quality of the outer layers of the PCB.

10. Second Plating: Adding Protection and Durability

Now, we head back to the plating room for the second plating step. This is like adding a protective shield to the PCB to make it more durable and reliable.

First, just like in the previous plating step, we electroplate the panel with a thin layer of copper. This additional copper layer helps to further strengthen the electrical connections and improve the overall conductivity of the PCB. It’s like adding an extra layer of insulation to a wire to make it safer and more efficient.

After the initial copper plating, the panel usually receives tin plating. Tin is a great material for this stage because it has some really useful properties. It can protect the areas of the panel that we want to keep covered with copper during the next etching stage. It’s like putting a protective cover on a piece of furniture to keep it from getting scratched.

The tin plating also improves the solderability of the PCB. This means that when we come to the soldering stage later on, the components will stick better to the PCB. It’s like using a special glue that makes things stick together more firmly.

Once the tin plating is done, the panel is in a better state to move on to the next step. The tin is protecting the desired copper, and we’re one step closer to having a fully – functional PCB that can withstand the test of time and use.

11. Final Etching: Defining the Circuit

After the tin plating has done its job of protecting the desired copper areas, we move on to the final etching step. This is like the last carving on a beautiful piece of art, making sure all the details are just right.

In this stage, we use chemical solutions again. But this time, their job is to remove the unwanted exposed copper and the copper that’s still under the remaining resist layer. It’s like a super – efficient cleaner that only targets the parts we don’t need.

The chemical solutions work their magic, and the excess copper is gradually removed. Meanwhile, the tin that we applied earlier acts like a strong shield. It protects the valuable copper that we want to keep for the final PCB. It’s crucial that the tin does its job well because any damage to the protected copper could affect the functionality of the PCB.

Once the etching is complete, the conducting areas and connections on the PCB are properly established. It’s like building all the roads and bridges in a city, making sure everything is connected in the right way. This is a really important step because these conducting areas and connections are what will allow the electricity to flow through the PCB, making it a functional circuit board. Now, our PCB is looking more and more like the final product, with all the necessary copper traces in place and the unwanted parts removed.

12. Solder Mask Application: Protecting the Circuit

Before applying the solder mask, the panels need a good cleaning. We want to make sure there’s no dirt or dust left on them. It’s like cleaning a window before putting up a new sticker.

After cleaning, we cover both sides of the board with an epoxy solder mask ink. This ink is like a special paint that will protect the circuit.

Next, we use UV light. The boards are blasted with UV light, which passes through a solder mask photo film. It’s like shining a light through a stencil. The covered portions of the ink remain unhardened, and these are the parts that will be removed later.

Finally, the board goes into an oven. This is to cure the solder mask. Curing makes the solder mask hard and durable, like baking a cake to make it firm. The solder mask is really important as it protects the copper traces on the PCB from getting damaged and helps prevent short circuits. It’s like a protective shield for the PCB, keeping it safe and sound.

13. Surface Finish: Enhancing Solder – ability

Now that our PCB is almost complete, it’s time for the surface finish step. This is like adding a special coating to a car to make it look better and work better.

The main goal of surface finish is to add extra solder – ability to the PCB. We do this by chemically plating the PCB with gold or silver. Gold and silver are great for this because they are very good conductors of electricity and they don’t oxidize easily. It’s like using a super – strong and reliable bridge to connect different parts of the circuit.

Some PCBs also go through a process called hot air – leveling. During this process, hot air is used to make the pads on the PCB uniform. It’s like smoothing out a bumpy road so that cars (or in this case, electrical signals) can travel smoothly.

The type of surface finish we choose depends on the specific demands of the customer. For example, if the PCB is going to be used in a high – end electronic device that needs to have excellent electrical performance, we might choose to plate it with gold. Gold provides a very low – resistance connection, which is perfect for high – speed signal transmission.

On the other hand, if cost is a major factor and the application doesn’t require the highest – level performance, we might go for a different option like tin plating. Tin is a more affordable alternative and still provides good solder – ability.

After the surface finish, our PCB is starting to look and function like a top – notch product. It’s ready for the next step, which is adding some important markings and getting tested to make sure everything works as it should.

14. Silkscreen: Labeling the PCB

Now that our PCB has gone through so many steps, it’s almost ready to be a fully – fledged product. But there’s one more important thing to do before the final testing and cutting: the silkscreen step.

This is like adding labels to a box to tell you what’s inside. We use an ink – jet printer to write important information on the surface of the PCB. This information can include things like component names, reference designators, and even company logos. It’s really helpful for people who will be working with the PCB later on, like technicians who need to assemble components or troubleshoot any issues.

For example, if there’s a resistor on the PCB, the silkscreen might have a label like “R1” next to it. This makes it easy to identify which component is which. It’s like having a map with all the landmarks clearly labeled.

After the ink – jet writing is done, the PCB is one step closer to the finish line. It then moves on to the last coating and curing stage. This final coating and curing process helps to protect the silkscreen markings and also gives the PCB a nice, finished look. It’s like putting a clear coat of paint on a piece of furniture to protect the wood and make it look shiny.

15. Electrical Test: Ensuring Functionality

As a final and crucial step, we conduct electrical tests on the PCB. This is like giving a final health check to a car before it leaves the factory.

We can use an automated procedure to confirm the functionality of the PCB. This procedure checks if the PCB is working as it should and if it meets the original design requirements. It’s like a strict teacher checking if a student’s work matches the assignment.

One advanced method we use is called Flying Probe Testing. This method uses moving probes to test the electrical performance of each net on a bare circuit board. It’s like a little explorer, carefully checking every part of the PCB to make sure there are no electrical issues, such as short circuits or open circuits.

During the test, the probes make contact with specific points on the PCB, just like a doctor checking a patient’s vital signs at different points in the body. They measure things like resistance, capacitance, and voltage to ensure that the electrical signals are flowing correctly.

If any problems are detected during the electrical test, the PCB will be sent back for further inspection and possible repair. This ensures that only high – quality PCBs move on to the next stage, which might be integration into larger electronic devices.

16. Profiling and V – Scoring: Final Shaping

Finally, we reach the last step of the PCB manufacturing process – profiling and V – scoring. This is the stage where we cut different boards from the original panel. It’s like cutting slices from a big cake!

There are two main methods for this. One is using a router. A router is like a special cutting tool that moves along the edges of the PCB panel. As it moves, it leaves small tabs along the board edges. These tabs are like little connectors that keep the boards attached to the panel until we’re ready to separate them.

The other method is V – scoring. With V – scoring, we cut diagonal channels along both sides of the board. It’s like making two slashes on the sides of the board to create a V – shaped groove. These grooves make it easier to break the boards apart from the panel later on.

Both the router and V – scoring methods are designed to ensure that the boards can be easily popped out from the panel. Once the boards are cut, they are now individual PCBs, ready to be used in all kinds of electronic devices. And that’s the end of the long and detailed PCB manufacturing process! From the initial design to the final cutting, every step is crucial in creating a high – quality PCB that powers our modern electronics.

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