Complete Guide for PCB Assembly Process

There is a printed circuit board within every electronic device that makes it work today. Whether you're looking at smart speakers for your home, your new smart thermostat, or your car's digital speedometer, the PCB is the heart of electronic devices. Creating functional electronic devices requires much more than just assembling components.

It is critical to get the PCB assembly process right the first time. A single misstep here could result in malfunctions, lack of functionality, and even accidents. In this post, we will cover some of the most critical PCB assembly process steps.

There's no board manufacturing here

First of all, it is important to understand that PCB assembly occurs at a specific time during the development of an electronic device. It is not about manufacturing that occurs first. The bare board itself will be manufactured, along with all of the necessary layers, traces, and other important steps, and then it will be assembled.

PCB assembly is simply the process of putting together various components in one place and actually getting something functional out of them. It is the process of taking a newly manufactured board and adding components to it, and then checking to see if it can perform as it is supposed to.

Learn about printed circuit board assembly technology

There is more to assembling a printed circuit board than just the raw components and a well-designed circuit board. In this case, there are several options to choose from, and each brings something new to the table when it comes to technology. Aside from surface mount technology (SMT), there are also manual soldering methods, pick and place machines, and other methods to go through the entire process.

Some PCB assembly processes require one technology, while others require two or more technologies. For example, many boards require both through-hole and surface mount technologies. When selecting a company to handle your project or production, it is important to understand when, where, and how those technologies can be integrated.

Lastly, it's important to understand that PCB assembly steps vary between different technologies. Below, we've outlined an overview of some basic steps and how they vary.

Overview of Printed Circuit Board Assembly Process

Component Placement: Following the assembly of the PCB, the next step is assembling the components on the board, either manually or with the assistance of machinery (pick and place systems). During THT assembly, components are placed by hand, which requires incredible precision. As for SMT assembly, components are commonly placed on the board using robotic systems. Automated placement is more precise and faster than manual placement.

Solder Paste: As part of the traditional PCB assembly process, the first step is the application of solder paste to the boards. Note, however, that this is not the case with THT, while SMT does require the application of paste as well as printing of the boards.

Reflow: In the traditional PCB assembly process, the next step is reflow, which involves melting the solder and then resolidifying it. In an oven, the board is heated and the solder liquefies, ensuring that connections are formed before being moved to a cooler, where the solder is cooled.

It is important to note that the THT process does not require reflowing solder, but rather inspects the board and corrects the component placement as a second step in the process. As a result of the manual placement process – a visual inspection combined with a design transport frame is crucial to ensuring accurate placement.

A reflow soldering process is also included in the SMT process. The board is sent through a furnace, which melts the solder paste, allowing it to flow as necessary, before it passes through a series of coolers that gradually bring the temperature down, causing the solder paste to solidify on the board and cement the components in place.

Through-Hole Part Insertion:Traditional reflow and inspection processes require that through-hole insertion be performed manually. Soldering may also be done manually, or wave soldering may be used.

During the THT process, wave soldering also occurs. The board moves over liquid solder and is cooled to solidify the solder.

The SMT process has no corresponding step (it is actually already finished after only three steps, although a visual inspection is still recommended to ensure accuracy and to reduce errors).

Inspection: As part of the traditional PCB assembly process, the next step is a visual inspection of the board, soldering, and components. Please note that this step has already occurred in the THT and SMT processes in which the board has been assembled.

Cleaning and final inspection: The final step in the traditional assembly of a PCB is the inspection, cleaning, and re-soldering of the board, the solder points, and the components at the end of the process, ensuring that there is no debris or excess solder on the board.

Choosing the Right PCB Assembly Process

There are times when SMT assembly is faster and more accurate than traditional PCB assembly or THT assembly, but it is not always the best choice. The THT method may be a better choice if you need just a single prototype board assembled. Each situation is unique and there is no one solution that always works.

We PCBAonline understand that each client has different needs, budgets, and goals. We aim to provide exactly what each client needs. We can help you to produce a single prototype to prove your concept or to move into full production with thousands of units. For more information about our services and capabilities, feel free to contact us today.

All-in-one printed circuit board assembly services, testing service and capabilities

We source components from chip suppliers around the world, such as Arrow Electronics, Digi-Key, Mouser and others. In addition, we maintain a large inventory of common parts. Our engineers will recommend fair-price alternatives if we cannot source a specific component.

PCBA testing

Test of functionality : Board & system level testing, as well as engineering support for developing test platforms
Flying probe test including boundary scan

PCB Assembly Services

SMT: Single & double-sided, SMT assembly
NPI: Introduction of a new product
Multi-technology: through-hole, SMT, electro-mechanical assembly
Plated through-hole: Soldering with selectivity

Engineering services

Value add engineering services
Develop control plans & PFMEA
DFM, DOE, DFT

Quality Control

To ensure high quality while accelerating the PCBA process, we have integrated state-of-the-art production equipment with advanced management systems.

For quality, durability, and performance, we only source components from authorized distributors.

YYFAB manufactures and assembles all boards to ensure quality and consistency.

How to choose a good ems supplier to reduce the cost of pcb assemblyBLOG

Choosing a good EMS (electronic manufacturing services) supplier is an important step in reducing the cost of PCB assembly. An EMS supplier provides a range of services related to the manufacturing of electronic devices, including PCB assembly, component sourcing, and testing. By carefully selecting an EMS supplier, you can ensure that your PCB assembly process is efficient and cost-effective. One of the key factors to consider when choosing an EMS supplier is their experience and expertise in PCB assembly. The supplier should have a proven track record of successfully assembling PCBs for a variety of applications and industries. They should also have the necessary equipment and processes in place to handle the assembly of your PCBs in a timely and cost-effective manner. Another important factor to consider is the supplier's ability to source components for your PCB assembly. The EMS supplier should have established relationships with a variety of component manufacturers and distributors, allowing them to quickly and easily obtain the components needed for your PCB assembly. They should also be able to provide the necessary documentation and certification for the components to ensure that they are of high quality and meet the required specifications. In addition to experience and component sourcing, the EMS supplier should also be able to provide testing and quality assurance services for your PCB assembly. This includes ensuring that the assembled PCBs meet the required specifications and performance standards, as well as performing any necessary compliance testing. The supplier should also have a robust quality management system in place to ensure that the PCB assembly process is consistent and reliable. One of the key ways to reduce the cost of PCB assembly is to choose an EMS supplier that offers flexible pricing options. This may include volume discounts for large orders, as well as the ability to adjust the level of service provided based on your specific needs. For example, you may be able to reduce the cost of PCB assembly by providing the components yourself, or by using your own testing equipment and processes. In addition to considering the EMS supplier's experience, capabilities, and pricing options, it is also important to evaluate their communication and collaboration capabilities. The supplier should be able to work closely with you to understand your specific needs and requirements, and to provide timely and accurate updates on the progress of your PCB assembly project. This will help to ensure that the PCB assembly process is smooth and efficient, and that any issues or challenges can be quickly addressed. Overall, choosing a good EMS supplier is an important step in reducing the cost of PCB assembly. By carefully evaluating the supplier's experience, capabilities, pricing options, and communication and collaboration capabilities, you can ensure that your PCB assembly process is efficient, cost-effective, and of high quality.

Know common PCB colors and uses all hereBLOG

1. What does the PCB color mean? PCB color generally refers to the oil color on the board that is most intuitively seen when you get a PCB board. The color of the PCB surface is the color of the solder resis t . PCB board dyeing pigment is a kind of hardened resin, the main resin is colorless and nearly transparent, and green is the color matching of toner just like other colors. We print the colors onto the PCB by screen printing . PCB colors can be green, black, blue, yellow, purple, red and brown. There are also some manufacturers who have ingeniously developed PCBs in various colors such as white and pink . 2. Is there any difference between different PCB colors? 1 ) . Green PCB Green PCB is the most popular color . Therefore, many people have always misunderstood that the PCB is green or mostly green. Green increases the clarity of the PCB , because the green PCB will have a sharp contrast with the white text, thereby enhancing readability . Additionally, the green PCB surface finish reflects less light, helping to reduce glare. Green PCB 2 ) . White PCB White PCBs look clean and crisp in various environments and are becoming more and more popular. However , white PCBs are still not the first choice because white PCBs are easy to hide traces . But the white PCB looks especially contrasty against the black silkscreen. White PCB 3 ) . Yellow PCB In the past, yellow PCBs were often used, but it is not so practical now. Yellow PCB can quickly meet different needs such as style, cleanliness and visibility. Yellow PCBs have one obvious disadvantage: poor contrast with traces and silkscreen . 4 ) . Blue PCB Blue PCBs are considered as the thick boards for labels as it provides a significant screen printing contrast . This PCB color is not as eye-catching as green PCB, black PCB or white PCB, but blue PCB is the preferred PCB color because it provides excellent aesthetic options. A blue PCB is better used for LCD because blue PCBs do not produce sharp contrasting edges and bright background colors. Blue PCB 5 ) . Red PCB Due to some advantages of red PCB , many PCB manufacturers are keen to adopt red. The red PCB provides excellent visibility and clearly defines the contrast of traces , planes and blank areas . The silk screen looks very beautiful against the red PCB. Red PCB 6 ) . Black PCB Black PCBs are as popular as white PCBs. These two PCB colors create low contrast, allowing easy marking of important components . However, the main disadvantage of black and white PCBs is that specific details may spotlight and have small shadows . This shadow makes tracking difficult. Therefore, it is not advisable to use black PCBs in various high-temperature applications because black PCBs may discolor the silkscreen . Moreover, the black PCB board is a mixture of cobalt and carbon, which may have poor conductivity . Black PCB 3. Which process is used to complete the PCB color? Different colors do not affect how the PCB is manufactured . Copper is still placed on one or both sides, and the PCB becomes smooth as copper is added or removed. The copper layer on the PCB is very thin, which is why the green color stands out so much. The thin copper layer is eventually covered during soldering to keep it from oxidizing, which is how the solder mask is made. It's also standard in green in many cases. In other colors the copper won't show through clearly so it can be hard to see where the traces are. After the traces are drawn, place the components in place. These need to be soldered in place according to the board diagram. Finally, with the components in place, the board is tested. If they work, they go into production. Most printed circuit boards need to be designed by engineers and prototypes need to be made before going into production. PCB 4. Why are most PCBs green now? This is mainly because the green solder mask process is the most mature and simple, and the green PCB board is also more environmentally friendly. In addition to green, the color of the circuit board also has white, yellow, red, blue, matte, and even chrysanthemum, purple, black, bright green and so on. White exists because we have to use it to make lamps. The use of other pcb colors is mainly to distinguish different product samples. In the whole stage of the company, from research and development to product landing, it depends on the various uses of PCB. The color of the experimental pcb board may be purple, the color of the button pcb is red, and the color of the pcb inside the computer is black. Several reasons for choosing green PCB are listed below: 1 ) . Glass epoxy resin material Glass epoxy is a material used in the manufacture of circuit board solder mask . This material used to be green and became the standard color for all fitters in the industry to use the same glass epoxy. Later glass epoxies of some other colors were introduced as well, but assemblers always considered green. 2 ) . Contrast between green and white printed text Assemblers often find it easy and time-saving to scan green boards because they are used to and very familiar with the color. They say it takes a lot of time to scan some boards of different colors. Another reason is that green places less strain on the eyes when scanning compared to other colors. Green is used because it also contrasts with the text printed in white on the board layout. 3 ) . It is widely used in the military How military standards goes has a big impact on green circuit board. Many people believe that green is very effective in circuit boards for military purposes. The military requires suppliers to provide green circuit boards, and these suppliers also supply other customers. These boards ended up as leftovers from military suppliers. So not only are assemblers, line workers or other customers considering green, the military is also accepting green for circuit boards. 4 ) . Exposure rate of solder mask The board requires a higher soldering rate, and there are other colors, but they don't provide a higher solder mask for circuit board. Those with darker colors, such as blue, white, or brown, have high pigmentation, so they have a dark solder mask. Mainly white and black solder mask with high exposure. But green provides a dark shade for worker exposure and high tolerances in the design. 5 ) . M achine recognition is better to Green PCB Generally speaking, electronic products have to go through board making and assembly of components. There are several steps to making a circuit board in the yellow lighthouse. When the PCB color is green, the visual effect is better in the yellow light room . But that's not the main thing. When soldering, it must be checked by brushing tin on the solder paste, the pads and the AOI on the back. These processes require optical positioning and calibration, and the green PCB background color has a better recognition effect on the instrument. 6 ) . Green PCB will be more comfortable Part of the inspection process is observed by workers (but now most of them use flying probe inspection instead of manual work), staring at the board under strong light, the green pcb board is more friendly to the eyes . 7 ) . Green PCB can reduce production cost Due to the wide range of uses of green PCBs, green PCBs can be used in both production and procurement fields. In addition, in mass production, the same color paint can be used to reduce production line costs, so the purchase cost of green paint will be lower than other costs. Therefore, green is the most common resist, which has advantages in terms of manufacturing cost and lead time . 8 ) . Green PCB is relatively environmentally friendly. The waste board will not release toxic gas when it is recycled at high temperature. Other PCB colors, such as blue and black, are doped with cobalt and carbon respectively, since they are less conductive and have a risk of short circuits. In addition, like black lights, purple lights, blue lights, etc., the color of the circuit board is too dark, which will increase the difficulty of maintenance of the main board , and the process is not easy to control. PCB Taking the black board as an example, the black board is most likely to have problems in the production process and raw material ratio. A little carelessness will cause obvious color difference, resulting in a high PCB defective rate. The traces of the black circuit board is not easy to distinguish, which will increase the difficulty of later maintenance and debugging . Many PCB factories do not use black PCBs very much.