Printed circuit boards are the foundation of electronic devices. These boards serve as a platform to connect electronic components. They are core aspects of electronics manufacturing. Therefore, they need to be functional enough. The process of manufacturing PCB is a complex one. Also, this process begins with a concept and ends with a finished and functional PCB assembly.
However, there are several steps involved in this manufacturing process. The result of those carefully taken steps is the finished board. Therefore, this board creates a platform to mount electronic components. To understand how PCB works, it is important to know more about its manufacturing.
Therefore, we have decided to discuss the origins of bare boards. Also, we will provide an in-depth knowledge on how to construct a high-quality PCB.
What does PCB Manufacturing Entail?
There are several ways of manufacturing a printed circuit board. Also, PCBs consist of various substances. The most commonly used material is FR4. This material offers a great degree of stability under a varying degree of temperature. Also, this material doesn’t easily breakdown. There are other cheaper materials for PCB manufacturing. However, it is important to consider some factors when choosing a material.
Where the dielectric constant of a material becomes important, PTFE based PCBs are advisable. However, this PCB material is difficult to work with. Copper clad is an important material for making tracks for components. Also, copper cladding features a thin layer of copper bonded to the board. FR4 material is suitable for this bonding. However, PTFE makes bonding more difficult due to its nature.
PCB manufacturing involves complex procedures to ensure the functionality of a finished product. Also, the fabrication process of a PCB can vary based on the number of layers. Therefore, the differences in the PCB structure may require several steps during manufacturing.
The complexity of a PCB determines the number of steps required during manufacturing. There are several types of PCB. PCBs can be single-sided, double-sided, or multilayer. Also, a high complex circuit board requires more steps.
PCB manufacturing entails converting design files into a physical circuit board. These design files include netlists and Gerbers. The manufacturing process often starts with design output files. These files are often generated during the design stage. Also, the manufacturing process starts after receiving the design files.
PCB manufacturing is very crucial for any electronics production. Therefore, the functionality and quality of a circuit board depends on its manufacturing.
Materials Used in PCB Fabrication
There are several materials used for manufacturing a circuit board. Each of these materials plays a vital role in the performance of a PCB. For every PCB, there are three major types of materials used. These materials include:
This is the most common material used in PCB manufacturing. Also, FR-4 is a glass-reinforced epoxy laminate. This laminate sheet is special since it is flame-retardant and water-resistant. Also, FR-4 offers great strength-to-weight ratios. FR-4 features a high tensile strength. This material serves as the base of most PCBs. However, it is not ideal for use in high-power LEDs.
Typically, each PCB utilizes metal in its fabrication. Copper and aluminum are examples of metal used by PCB manufacturers. Copper is an effective PCB material that allow the use of SMT for integrating all components. Also, metals offer great mechanical stability and durability. Therefore, PCBs fabricated with metal have longer shelf life.
Also known as Teflon, PTFE is a type of plastic material. In addition, it is ideal for use in high-frequency and high-speed applications. This highly flexible material doesn’t offer any resistance. Also, this material is suitable for applications that require tight tolerances.
PTFE is lightweight and is widely used in several industries. Also, this material can offer great temperature stability. PTFE has great physical strength and flame resistance.
Types of PCB Base Materials
There are various copper-clad laminates used for PCB manufacturing. However, there are some PCB base materials used in PCB manufacturing
This material has 99.5% purity. Also, copper foil is available in a wide variety of thicknesses. In some countries, thickness is measured in ounces per sq.f.
This material features a paper base. However, it is wholly impregnated with epoxy resin. Epoxy getinax is an FR3 material that is commonly used in home appliances. Also, this material is self-extinguishing.
Phenolic resin impregnated paper base material is opaque. This material is ideal for use in consumer electronics.
This is a commonly used PCB based material. Epoxy fiberglass features great electrical properties and mechanical strength. Also, this mechanical strength is a result of the glass fiber reinforced with epoxy resin.
PCB Manufacturing Process
There are several steps involved in the PCB manufacturing process. Each of these steps needs to be carefully carried out for a successful PCB manufacturing.
The first step in PCB manufacturing is the design. The design serves as a blueprint. Also, manufacturers use computer software to achieve this process. You can use a trace width calculator for the details required in the external and internal layers. Also, the manufacturer needs to print out the design. A plotted printer helps to achieve this process.
After printing the design, there are two ink colors on the inner layer of the board. The black ink indicates the conductive copper traces. The non-conductive areas are then indicated using clear ink.
Creating the substrate
The substrate serves as the base material that holds the components on the structure. The manufacturer pre-bonds copper to the two sides of the layer. After this, the copper etches away to reveal the design from the printed films.
Most PCB manufacturing involves the application of a layer of copper on the whole surface of the substrate material. Therefore, this creates a blank PCB with copper on the surface. Therefore, the manufacturer removes the unwanted copper through subtractive methods.
This process utilizes a photomask with chemical etching to remove copper areas from the substrate. A photoplotter creates the photomask. The photoplotter takes the design from software.
Most PCBs feature multiple layers. These boards are also referred to as multilayer PCBs. Also, these boards feature several trace layers bonded together via lamination. The board will begin to take its shape as you fuse the layers together. Manufacturers use metal clamps to hold the layer during the lamination process.
Pressing of layers
This process involves using a mechanical press to press layers together. Also, the manufacturer punches pins through the layers to align and secure them properly. You can remove these pins based on the technology. The laminating press applies pressure and heat to the layers of the PCB.
This is an important step in PCB manufacturing. Here, a computer-guided drill creates holes in the layers. This automated drilling machine functions by computer files and programs. Therefore, these holes expose the inner panels and the substrate. Every layer of the PCB requires the connection of one layer to another. The small holes created are commonly known as Vias.
To ensure solderability of the components, the manufacturer plates pads and lands. Bare copper is not solderable. Therefore, the manufacturer must plate the surface with a material that enhances soldering.
Before applying the soldermask, you need to clean all the panels. After this, the manufacturer applies an epoxy with the solder mask film. The green color you often see on a PCB is a result of the solder mask. Also, the manufacturer uses ultraviolet light to remove any unwanted soldermask.
Silkscreening is an important process of PCB manufacturing. This step involves the application of vital details on the PCB. Therefore, silkscreening applies text to the external surface of the PCB. Also, screened text can reveal component designators and additional features to aid the PCB assembly process.
This step involves plating the PCB with conductive materials. There are several surface finish options. These include immersion silver, hard gold, and more. Also, the application demands of the PCB will determine the surface finish type to use.
This is the final step of the PCB manufacturing process. Before assembling the PCB, a technician must carry out some tests on the board. Unassembled PCBs require a bare board test. Here, the technician must verify every circuit connection as correct on the finished PCB. The testing method used must adhere to the standards in the PCB industry. Also, there are guidelines for testing of unpopulated PCBs.
How to Achieve an Effective PCB Manufacturing
The processes of PCB manufacturing comprise several entities. In most cases, the PCB manufacturer may design a PCB based on the design provided by the user. There has to be collaboration of design considerations and components between the CM (contract manufacturer) and OEM (original equipment manufacturer).
Design for manufacturing considerations
Design for manufacturing looks at how the design can go through the different stages of the manufacturing process. Therefore, the manufacturer will have DFM guidelines that the equipment manufacturer can consult. Also, the designer may ask for these guidelines to ensure the PCB design adapts to the usual production process.
The designer needs to consult the fabricator on the components available. Also, the PCB fabricator will have the components required by the design.
Equipment manufacturers design PCBs using more expensive materials than contract manufacturer expects. Therefore, it is very important that both entities agree to the materials available. Also, they should both agree on what is best for the PCB design. However, a cost-effective option should be considered.
This ensures the complete production of the PCB, communication is important. The CM and OEM must communicate. This will help to ensure the PCB meets the design specifications of the OEM. Therefore, both entities must utilize the same file formats. In addition, this will prevent any misinformation or error that may occur.
Common PCB Manufacturing Defects
Some common defects occur during PCB manufacturing. However, elimination of defects is important during PCB manufacturing. Therefore, it is important to understand the common defects and how to avoid them.
Electromagnetic compatibility issue is a major concern during PCB manufacturing. This issue is a result of possible design flaws. Therefore, manufacturers can minimize this defect by lowering the ground area of the PCB. Minimizing the contact area of the PCB can prevent electromagnetic compatibility.
Plating hole defect
Drilled holes in a board transmit electricity from one side to the other. Hole plating during PCB manufacturing can lead to errors. If there is incorrect copper deposition, it will lead to plating voids. This will leave gaps in the wall without copper coating.
Also, this could occur as a result of holes contamination. Manufacturers can prevent this defect from occurring by following appropriate directions.
Chemical leak problem
The leftover trace elements that weren’t appropriately removed during PCB fabrication can cause chemical leak. Also, the corrosion of circuit boards is a problem. Manufacturers can prevent chemical leak issues by cleaning the board thoroughly. Any residue can make the boards corrode and this can cause a short circuit. Therefore, it is important to check for chemical leakage during inspection.
Absence of solder mask between pads
This is a common error encountered by PCB manufacturers. This is as a result of abnormal connection with several traces. Also, this is a very small defect that is difficult to identify. If left undetected, it can burn up the components. Therefore, the best solution is to add a solder mask between the pads. This helps to seal the gap between the PCB and the stencil.
Machines used in PCB Manufacturing
There are several machines used in PCB manufacturing. Some PCB manufacturing processes require the use of automated machines.
PCB drilling machine
This machine is widely used for creating holes and slots in a PCB. The PCB drill helps you to create a specific hole size on the PCB. There are different types of drill machines. However, the twist drill is the most widely used drill machine.
The PCB laminator is one of the machines used in PCB manufacturing. Also, this machine laminates different circuit layers in a board. A laminator uses pressure and heat to laminate the layers of the PCB.
This is a device that produces image with the use of light. A photoplotter exposes images onto black and white film. However, it uses a light source to achieve this. A photoplotter designs the photomasks for PCBs. Also, data instructions written in Gerber format guide this machine. Also, these instructions draw the shapes and lines required to complete PCB designs.
The BB4. 3 etching machine is widely used for PCB etching. This machine is ideal for the PCB prototype production. PCB etching machine helps to create the copper traces on the PCB. The etching process involves removing unwanted copper from the PCB.
This is a single machine that can carry out the necessary functions to create a prototype board. Also, the CNC machine is very crucial in PCB manufacturing.
Guidelines for PCB Manufacturing Process
PCB manufacturers need to take many aspects into consideration. In some cases, manufacturers have made errors due to their ignorance.
Get a clear and detailed BOM
A clear and well-detailed BOM can help you to save cost and time. The BOM clearly states the specification of a PCB project. Also, it defines components that shouldn’t be on the board.
Create the appropriate PCB design
The appropriate PCB design will save you time. Therefore, focus on a balanced build with regards to layer count. Ensure the multilayer PCB features even layer counts. Also, specify the copper weight and ideal PCB finish. Don’t use silkscreen for small components. Also, consider using local fiducials for very fine pitch components like xilinx Fpga.
Check out the board materials
This is an important consideration for PCB manufacturing. You need to know the type of materials you will be using for your PCB manufacturing. You have to select the board materials based on the applications of the finished boards.
Choose your via type carefully
Different types of vias are available for use in BGA PCB boards. These vias are important elements in a board. Also, they help to create necessary connections between several components. For the best PCB design, the number of vias should reduce. Also, it is important you understand the current carrying capabilities of the vias.
Select appropriate parts
This can be the most tedious step in a PCB project. Selecting the appropriate part can help to reduce errors. Also, it helps to ensure the quality of the PCB. There are several components available in the PCB market. Ensure you choose a part that is easily available. Don’t use a component that is no longer in production.
The functionality of a PCB can impact the performance of an electronic device. Therefore, it is important to pay attention to PCB manufacturing. PCB manufacturing entails different processes. These processes are crucial for the successful manufacturing of a circuit board. In this article, we have discussed vital information about PCB manufacturing. We hope this piece of information will widen your knowledge on this PCB aspect.