PCB boards are all around us in every gadget we use. Be it the smartphone or a simple calculator, their function depends on the performance of PCBs.
Do you know what the PCB circuit boards made of are?
Have you ever opened up your iPhone to see what's inside?
You would find only a few things, from the digitizer, battery to soldering, and, of course, the PCB. The logic board is what keeps your iPhone running, and any damage to it results in your phone not being able to power on again.
The compact circuit board design of the iPhone X, for instance, has wowed many analysts and techies. It is a feat of engineering that not many companies have been able to surpass.
So, what is it that makes circuit boards so unique?
What makes one circuit board better than the other?
What does a circuit board consist of?
We have prepared this helpful guide where you can learn about the materials used to make PCBs.
You can also get a picture of how a manufacturer produces them. Let's begin by taking a look at what are the circuit boards made of.
Then, we will take a look at how you can make your circuit boards.
At the end of this article, we would guide you through the path to ensuring that you get the best from the right vendor.
1.1: What are the PCB prototype board or PCB Circuit Boards Made Of
Circuit boards are also known as printed circuit boards or PCBs. They drive the different electronic and electrical equipment and tools that we use every day.
Most of the PCBs are formed by combining two or more layers depending upon the complexity and nature of the device they will be used in.
PCBs use a variety of materials for their composition. One layer can be made from fiberglass or resin derived from paper. Other materials, such as copper, solder mask, and silkscreen layers, are also used.
In the next chapter, we will know what materials are the PCB circuit boards made of.
Image 1: PCB
1.2: What Materials are Printed Circuit Board Made Of
PCB is generally made from four layers of material bonded together by heat, pressure, and other methods. Four layers of a PCB are made of the substrate, copper, solder mask, and silkscreen.
The material encompassed by the printed circuit board includes:
• Copper: the copper gathers on the thick layer of foundation known as the substrate. Depending on the type of board and use, there can be one or two copper layers present.
The copper layer can exist on one side of the PCB, or it may be present on both sides of the substrate. Simple electronic devices make use of PCBs, which have a copper layer only on one side.
Copper layers are much thinner and delicate than the substrate.
The copper used in PCBs is referred to by weight and presented in ounces per square foot. Most common PCBs come with a copper content of 1 ounce of copper per square feet.
While the amount of copper present in the PCB determines the amount of power it will exchange.
• Silkscreen: the silkscreen performs the responsibility of making the printed circuit board readable to technology programmers by adding numerical and letter indicators.
• Substrate: the substrate is commonly known as FR4, which is an acronym for Fire Retardant.
It functions in providing a thick layer of foundation for the printed circuit board, which, of course, varies. However, you will find their thickness to change. It is the layer that offers rigidity to the PCB.
It can also be made from flexible materials which sometimes can be stretched, too. Recently many innovative materials are being used to create the substrate, some of which are even plant-based.
It is important to note that there are other types of board that does not make use of the above-listed materials. Instead, they make use of epoxies. A disadvantage attached to this type of commission is that they are thermally sensitive, making them susceptible to fast loss of their lamination.
One way to recognize this type of board is through the smell they give when undergoing soldering processes.
A green top layer of PCB is known as the solder mask and is applied over the copper layer to come in contact with other electrical parts. On Top of the solder mask, a silkscreen layer is provided to create marks and labels for placement of various components.
Image 2: Custom PCB
The substrate is generally made of fiberglass, which is also known as FR4. FR refers to the fire retardant and provides the foundation of the PCB. The substrate layer is the thickest in any PCB
Some other materials are also used for making the substrate, such as epoxy or phenolics. The boards made from epoxy resin suffer from thermal sensitivity, and the lamination can fade quickly in some instances.
You can find these cost-effective boards easily in the market and recognize them by the smell they give off. The material also needs the components to be soldered to it.
Image 2: PCB Material
Next, let us see how you can develop a custom circuit board using a computer application.
1.3: Types of PCB
As briefed earlier, the PCB is a crucial component in different electronics. Now, let's consider the masterpiece behind your TV set and remote; the TV set can change channels from a press on the remote due to the presence of a kind of PCB in the remote.
There are many applications of the PCB which ease our very existence and make our daily activities flexible. Depending on the use, PCB manufacturers make use of varying types of PCB to suit different products. The type of printed circuit board includes;
In the earlier part of this article, we mentioned that the substrate varies with use. In the single-sided type of PCB, the substrate contained is just one.
A suitable electrical conductor such as copper is used to shield a side of the substrate, the solder mask is present on the copper layer, and a silkscreen coat is usually used to mark the parts of the board.
This type of PCB entails designs such that only one side accommodates the circuit and another electronic component. They are commonly referred to in simple electronic manufacturing.
An advantage attached to this type of board is that it is more pocket-friendly than other printed circuit boards.
Unlike the single-sided printed circuit board, the double-sided printed circuit board has its two surfaces of the substrate coated with conductive metal layers with the parts fixed to the two sides.
The double-sided printed circuit boards are in more use when compared to the single-sided printed circuit boards. The holes in the double-sided PCB carries the function of connecting one circuit on a side to the course on the other side through one or two techniques.
The first technique through which the holes connect the circuit is the surface mount technology –this type of technology or method involves no wires.
The advantage of this method is that it saves space. The second method is the through-hole technology – this technology or process involves thin wires passed through the holes and soldered to the right component.
Multilayer printed circuit boards.
The multilayer printed circuit board serves a more function when compared to the double-sided printed circuit board.
This type of printed circuit board contains numerous layers of substrate boards with insulating materials parting them into single sheets. Of course!
When we talk about how much space can be saved, the multilayer printed circuit board has the capability of saving even more space than the double-sided printed circuit board.
The multilayer printed circuit boards can have up to 10 layers or even more. They are used in well-known inventions such as machinery and so on.
Rigid printed circuit boards
Combining the advantages of having a good number of layers with rigidity is a characteristic of this type of printed circuit board.
This type of PCB makes use of materials that prevent them from bending; the material used is the fiberglass. An example of the rigid printed circuit board is the board inside your device.
Flex printed circuit boards.
Of course, from the word "flex," the substrate contained here is flexible. Since the rigid printed circuit board cannot form the desired shape, the flexible printed circuit board can fit well into this category.
They offer an excellent advantage over the rigid type in that they are flexible and hold an advantage due to their cost.
The rigid-Flex printed circuit board offers the characteristics of both the rigid printed circuit board and the flex printed circuit board.
This type of printed circuit board allows a wooden printed circuit board to be attached to another flexible printed circuit board, which appears to be more difficult than other types of printed circuit boards.
Image 3: Custom PCB
1.4: PCB components
Irrespective of the mindset behind creating any device, there must be components required for different circuits.
Below are some of the features which are essential in any electronic product or device.
LEDs: the LED is an acronym that means led to the emitting diode. The led emitting diode allows current through it; this current is only permitted to flow in a direction.
Resistor: the resistor performs a critical function by regulating or controlling the current, and to determine their value, they are color-coded.
Battery: as the general function of the storm, it is responsible for the supply of energy. The battery is responsible for the supply of voltage to the circuit.
Transistor: the transistor renders a critical function in that it is responsible for the intensification of the charge.
Switch: the switch serves as a component that is used in the control of electric current. The button can be used to permit the entrance of current or block the access of wind.
Diode: the diode is a component that permits the entrance of electric current just in one direction. Other passages are blocked while electric current flows in only a guide.
Inductor: the inductor is responsible for the storage of charge.
2、What is PCB DESIGN?
Image 4: Custom PCB
2.1: PCB design basics
In discussing the basics of the PCB design, we require a background familiarity with the terminologies used. When referring to schematic capture, we talk about a program that permits the operator to make a schematic diagram of the component and other features.
The schematic capture is just the representation of this in a graphical way. Different terminologies used include:
Gerber files: the Gerber files refer to those Computer-aided design files sent to the printed circuit board producers to build the PCB layer structure.
PCB layout tool: the program responsible for the layout of the PCB permits for the wiring connection structure to be applied on multiple layers and which, after completion, allows the operator to generate the CAD files needed to make a printed circuit board.
2.2: PCB design steps
In this present age, there are different approaches to the designing of a PCB. Depending on the manufacturer of the PCB, there are many ways to do this. Below are the essential steps noted in the designing of a printed circuit board.
Step 1: use of a software
It is the designing of a printed circuit board with the use of software; it involves the schematic representation of the circuit with the help of the software. Examples of layout software used are computer-aided design (CAD) software, mutism software, and eagle software.
Let us make use of the eagle software in this article, and in doing so, we have; Open the software board designs>>>click on file menu>>>select new design>>>click on library menu>>>select from the drop-down menu 'pick devices/symbol'>>>double click on a relevant comment>>>add the components and represent the circuit with proper connections.>>>enter the rating for each element>>>click text editor on the command toolbar>>>click on variages>>>close the window>>>after the appearance of a black screen, save as an image format.
Step 2: the generation of film
With the aid of the finalized circuit board diagram of the printed circuit board layout, the generation of the film occurs.
Step 3: Selection of raw materials
Less expensive printed circuit boards manufactured from paper phenolic bonded with copper foil are used in simple devices. The value of the copper-clad laminate is 0.059 thick with either a single or double-sided board.
Step 4: Drilling holes
Hole in the PCB implemented using machine and drill bit. The first type of machine used in drilling holes into the printed circuit board is the hand machine.
This type of device requires the effort of the operator to make holes into the board. The second type of machine is the automatic type called CNC machines. The programs provide the convenience of punching holes on printed circuit boards.
Step 5: fixing the image
To print the layouts on the PCB, laser printers are one of the best options in doing this. The process involved in this includes; placing a clean copper layer on the printer>>>storing on the computer the designed layout film>>>printing of the command received from the computer by the laser printer.
Step 6: Etching and Stripping
This stage uses a variety of chemicals to eliminate the useless copper attached to the printed circuit board.
Step 7: testing
After completing the above process, the board will be tested to ensure its functionality. In these recent days, many devices have been manufactured to aid the testing of the large volume of printed circuit boards.
2.3: PCB design software list
• PCB Artist
• SOLIDWORKS PCB
• DesignSpark PCB
The above list is the program used in the design of printed circuit boards.
2.3.1: PCB design software comparison
In looking at the comparison between printed circuit board designs, we would consider two software: EAGLE CAD and DIPTrace. These two software is, of course, picked at random.
Capable of schematic captures with components linked to a library, creating patterns with the aid of a decent library editor, availability of perfect tutorial and support, great for smaller and simpler boards.
Electrical rule check, the schematic hierarchy for a design organization, forward and backward annotation between schematic and printed circuit board.
2.3.2: best PCB design software
Out of the significant number of PCB design software available these days, some plain ones are highly recognizable for their perfect functionality.
• Readily Applicable Graphical Layout Editor (EAGLE): the eagle is a PCB design software that is user-friendly with a moderate price. EAGLE has a wide range of proper functions,s which includes: batch execution of script files, copper cladding, and more.
• Altium Designer
• DipTrace Lite
• DipTrace Starter
• Easy EDA
Image 4: Custom PCB
2.4: PCB design rules
Some rules are associated with the printed circuit board design that uses it effectively; you need to remember it.
Width and Spacing: for the width and Spacing, the parameters are usually denoted as "x/y rules" the X in this stands to represent the minimum of trace width while they in this represent the Spacing, that is; the minimum trace spacing.
Thickness and size of the board: size and thickness can be set to suit the particular product. Many individuals use more boards on just a panel to conserve space and cost if mass production is done.
3、How To Make PCB Layout
3.1: PCB layout design
The printed circuit board layout design requires the technical know-how or professional skills that calls for the knowledge of the printed circuit board software, the printed circuit board computer-aided design system, and the skills or methods involved in the successful transfer of the primary circuit design to the final PCB.
3.2: PCB layout comparison
In the comparison of the printed circuit board, certain factors must be watched out for, and these include:
• Layers available
• Power delivery network analysis
• 3D modeling
• Differential pair routing
3.3: PCB layout tutorial
This section will detail these steps:
Step 1: conversion of the schematic to a printed circuit board
It is the first step associated with the PCB tutorial. After you have successfully done your schematics, you can convert into PCB by clicking on "convert to PCB" on the editor that you are making use of.
Step 2: drag and drop the component
The second step is to place the document exactly where you want to be positioned. If you are the type that prefers a clean looking printed circuit board, components with similar functions should be placed side by side.
Step 3: sketching a custom outline
The first thing to do is go to the layer menu and click on the board outline layer, click on the current outline, and delete it after completing a new system with the PCB tools.
Step 4: copper area
The copper area is the best thought of when many parts are joined to just a signal. This copper area can be created using the tools menu.
Step 5: Routing
Depending on the type of current, there are two approaches to this method. If you have a low current where you are creating the printed circuit board, the auto-router function can be used. In cases where there is a need for different track sizes, it would be better if this is done manually by you. The auto-router function can be found at the Top of the page.
Step 6: Holes
Of course, you might need to mount your printed circuit board on something; in so doing, holes are required. The Hole tool can be found on the Tools menu and then locate the spot you want.
Step 7: pictures and text
In doing this, you would need to stroll to the tools menu and locate either the image or text tool. You can position the text as you wish and change the required layer or the book itself.
Step 8: photo view
After completing the above steps, you can round up your work by viewing the result. You can change the color or some other features. Once you are ok with the product, click on "fabrication output" to buy the PCB.
4、PCB Reverse Engineering Software
In cases where the schematic may not be available, the data created from the printed circuit board reverse engineering can be used to produce replacement parts, or it can also give hints in repairing parts that already existed.
5、Custom Made Circuit Boards
We know that PCBs are complex elements, and it can get a bit difficult for hobbyists to design themselves a working circuit. The first thing that you will need is reliable software to create the blueprint of your PCB.
Then you can use many PCB design solutions such as Eagle from Cadsoft Computer, which does an excellent job of designing your PCB.
Prepare Schematic View
You have to prepare the schematic view to create your custom PCB. Access the component library that is present in your design software and places them onto the canvas. Now you have to connect the pins along with the lines that symbolize electrical connections in the software.
The same part number may confuse you a bit as you will find several options to choose from.
The different packages can include the surface-mounted chip or a Dual-in-line box (DIP). If you are a hobbyist or doing a DIY project, it makes sense to go for significant and noticeable system-in-packages (SIP) or DIPs.
You can find them quickly, and hobby outlets are far friendly when it comes to soldering them compared to surface mounted devices reserved for commercial applications.
The different packaging options can appear to be similar in the schematic view. However, things will start to appear different when you switch to layout view to begin your design.
You will need to provide the necessary ground and power signals apart from placing your interconnections and components; you can use the features such as GND, VDD, and VCC found in the Eagle library for the job.
You shouldn't also forget to integrate the connectors on the board so that the ground and power can be employed. At this stage, you will also have any external device you want, such as a potentiometer or LEDs.
Your design now needs to go through an electrical rule check or ERC after putting everything in place. The test is crucial to ensure that there is no error present, which will hamper the functionality of your circuit board.
Some of the common issues that you mace are wires which appear to be connected but are not in reality. You can check for little dots in your Eagle software, representing the connection intersections of the wires.
Other problems may include ground and power signals that you forgot to connect. So you should remember is that the automated tests won't tell you if your board is going to carry out the desired action, but it can always validate the electrical properties of your design.
Image 3: Schematic Diagram and Layout View
Access Board Layout View
After you have done everything you need to do in the schematic view, you have to move over to activate the board layout view. Then you have made the switch, and you will find the components spread randomly in your Eagle software. You will also see that the wires directly hook to the pins.
To make the picture a bit less messy, move the components until they make meaning. For example, you can move the connectors to the edges so that things make sense.
You still have much work to do to produce the circuit board. So you have to dedicate signals to the layers but remember that the different layers present in the same layer should not touch each other.
The professional version of the Eagle solution comes with an auto-layout feature that can route the signals with a single click.
However, for users of the standard version, you have to take things in your own hands. You may also find a design solution from your PCB manufacturer to take care of this step.
After you have laid down the signals, the time has come to run the DRC or the design check. The check ensures that holes drilled too close to a signal line.
It also notifies you if the traces are not at an optimum distance from each other or the edge of the board.
You can customize the rules, and sometimes your PCB vendor will offer a file that can be integrated with Eagle solution with specified DRC values. Then you can move ahead and upload your design files if your project passes the DRC.
You should utilize a particular layer to add silkscreen lettering to the Top. The printing will help you know which component fits, whereby presenting part numbers and outlines.
That enables you to avoid mistakes like placing a 100K resistor instead of a 1K one.
A Gerber file reveals the language of PCB design, and the 3each board can have many files associated with them.
You will have a separate file for specifications of the solder pads and different files for each layer. The drill files also carry the specifications of the drilling.
You can then upload the design with your manufacturer, who can use another program to present the final look of the layers, and you can also find out if the components are the right size to fit the holes.
With this, you have come to the end of creating a custom circuit board using design software. In the next chapter, we will explore how a manufacturer produces PCBs.
Image 4: Layout View
6、How are Circuit Boards Made
By now, you know how to custom design your PCB by reading the earlier chapter. The technology of PCB is complicated, and it needs to go through a multi-stage manufacturing process.
You also have to choose a manufacturer who has all the high precision equipment to bring your project to life. We are going to discuss the PCB manufacturing process in brief just for you.
1. Making the Substrate
You can think of PCBs as sandwiches that come in multiple layers. The base material that is found in the middle is known as the substrate. Then the substrate material is responsible for giving width to the PCB.
You can view a PCB from the side angle and find that the thickest layer is the substrate.
Traditionally PCBs were made with fiberglass substrate, which is rigid. Nowadays, you can find flexible substrate material.
Many materials can be, but one standard option uses special plastic for the substrate, which can tolerate high temperatures.
The material used to make the substrate is generally spread out. The manufacturer then dips it or sprays it with epoxy resin. Next, the material is rolled on to get the desired thickness, just like rolling your pie crust using a rolling pin.
The rollers stop rolling when the substrate reaches the desired thickness and passes to the next step, and the substrate is now placed in the oven so that it turns out solid and firm by curing it. After the completion of this step, you have created the very first layer of your PCB.
2. The Copper Layers
The copper layers are essential to carry electricity throughout your PCB. Depending on the purpose, PCBs have a simple or complex design. Apart from the foundation layer of the substrate, copper layers are another essential component.
Your PCB cam comes with a single layer of copper applied to the Top or two layers on both sides of the substrate. The PCB can also have numerous layers with other copper and substrate.
Some PCBs used in advanced devices or smartphones have more than 12 or 16 layers of copper.
Copper layers are much lesser in width than the substrate layers, and you won't have any electricity flowing through your circuit if they are absent.
The manufacturer can use a combination of different methods to bond the copper to the surface of the substrate. Any standard methods involve using heat, pressure, and adhesive so that the copper layers are fixed firmly on the substrate.
You can take your PCB for drilling after the copper has bonded with the substrate.
For your device to function, the PCB needs to transmit the charge to the right points from one layer to another layer in the board. You will have to create holes referred to as via for the cost to flow through.
The manufacturer has several options to drill holes on the PCB and may use a CO2 laser, UV laser, or other equipment.
The accuracy and efficiency of the drilling machine determine the preciseness and complexity of the PCB.
You have to clean the holes of any debris or any material that might have been left behind after the process of drilling. They can also be deburred to get any additional material clinging to the PCB.
After that, the inner sides of the vias are coated with copper to carry the charge from one layer of the circuit board to another.
Next, you have to print the pattern of the circuit on the PCB. The manufacturer can deploy the copper accurately following the design to get the way on board.
Otherwise, they may apply copper to the entire board and then remove the copper to etch out the circuit pattern.
The PCB may be subjected to an alkaline bath to remove any extra unnecessary copper.
What you need to add now is the other components such as transistors, capacitors, or LEDs on the PCB. You can solder the pieces onto the PCB using a soldering iron. Before adding the features, the PCB is passed through a succession of electrical tests using a grid tester or flying probe to ensure there are no short circuits or open connection.
Your manufacturer may also use a machine to pump out the parts to your PCB.
Image 5: Copper Patterns
3. The Final Solder Mask
The metals which remain exposed on the circuit board have a chance to get damaged. The nature of copper is to rust, which will render your PCB useless. You can adequately protect the copper plating and other components of the PCB by adding an extra protective layer on Top.
Generally, manufacturers use gold, nickel, or tin-lead to plate specific vulnerable parts of the PCB. To top it all, the manufacturer provides another layer on Top called the solder mask.
The green color that you see in PCBs is due to the application of the solder mask layer; the solder mask also has some other functions apart from covering and protecting all the metal parts that don't need to form a connection with anything, the layer of solder mask also ensures that current flows to the right places following absolute paths.
Sometimes you may also find a layer of silkscreen on Top of the solder mask, used to carve labels on necessary parts.
After everything is done, the manufacturer will trim and shed off any extra material or unnecessary parts that are not required in your PCB.
Image 6: Green Solder Mask
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