A printed circuit board (PCB) is an electronic component that is used in essentially all electronic devices to complete the circuit among various other components like transistors, capacitors, and resistors. A PCB has copper conductors in it to connect all these components with each other electrically. It is custom-designed to suit the needs of different devices.
To understand how a printed circuit board is assembled, continue reading this blog.
What is PCB Assembly?
You have understood above what a PCB is and the components it is connected with. The process of mounting these components on the bare printed circuit board and soldering them together is known as the PCB assembly process (PCBA). This process has no meaning if the final product is not tested. Therefore, consider PCBA completed only after successful testing.
PCBs are used in various industries ranging from consumer electronics and telecommunications to automotive and healthcare. It would not be an exaggeration to say that the entire functioning of a device may depend on its PCB. Therefore, the processes of PCB design & assembly are quite crucial when it comes to manufacturing an electronic device.
PCB Assembly: Components
Before exploring the PCB assembly process, you must know the components and different parts used in this process. As you have understood by now, PCB board assembly consists of connecting a fully functional assembly PCB board with components like integrated circuits (ICs), resistors, transistors and capacitors. Therefore, you may consider these to be the most crucial components of PCB assembly. Here, one should note that these are known as passive components.
Other passive components include inductors, transformers, different types of oscillators (ceramic and crystal), etc. Image tubes and displays, active crystals, MOSFET, BJT (Bipolar Junction Transistor), diode, Integrated Circuit (IC) chips and other similar components are called active components of PCB assembly.
Technologies Used in PCB Board Assembly
The process of PCBA can be carried out by various technologies. This includes SMT, PTH technology and manual technology. Usually, a combination of both SMT and PTH technology is used in the assembly process. Continue reading to understand these terms.
- SMT (Surface Mounting Technology): One of the most used technologies for PCB assembly, SMT is beneficial in mounting small, delicate parts, like resistors and diodes. Advantages of SMT include:
- Economical as compared to the manual process.
- Used to mount a large number of components on a small-size PCB.
- Used for handling a medium to large-scale assembly project.
PCBs assembled via this process may not perform up to the mark under extreme heat and/or pressure. Therefore, it is generally used to assemble PCBs in electronic devices/appliances that are not expected to heat up too much.
- PTH Technology (Plated Through-Hole): In this process, the pins of the components to be attached are soldered on the PCB after inserting them into the PCB holes. This can be done either automatically (using a machine) or manually. PTH is usually used in cases where bigger components are to be installed. Advantages of PTH Technology are:
- Strengthens the connection between the components and the board.
- Performs well even under high pressure and/or heat.
- Ideal for prototyping as the parts assembled by PTH technology are interchangeable.
The process is though more expensive and time-consuming as compared to SMT.
- Manual Assembly: In this process, the components are soldered manually, i.e., via hands rather than using a machine. The efficiency, precision and quality of PCB assembly carried out manually may vary from worker to worker. The advantages of manual assembly PCB boards are:
- Prototypes can be assembled without requiring much time or money.
- Components that cannot be soldered automatically are needed to be soldered manually.
The process cannot be used for assembling a large number of PCBs. Since one PCB is assembled at a time, the unit cost is too high as compared to SMT and PTH.
Viasion Technology Co. Ltd. is one of the trusted PCB manufacturers in China where prototypes and small-scale PCB assembly projects are also handled well.
PCB Assembly Process
The PCB assembly process includes various steps depending on the type of PCB and its requirements.
- The process usually starts with a PCB assembly drawing where the prototype is designed and its major functions/features are defined.
- After that, a printed circuit board is fabricated as per the design.
- A thin layer of solder paste is then applied according to the requirement which serves as a foundation for further steps.
- The next step is to place and position the components on the bare PCB carefully before they are soldered. Automated pick-and-place machines carry out this step.
- Then, machines are used to heat the solder paste to a certain level which leads to the melting of the solder. This step is known as reflow soldering as the PCB is passed through a reflow soldering oven in this step.
- Now, one of the most crucial steps, i.e., inspection is carried out. At this step, machines and PCB professionals, both run a thorough inspection to check all the soldered joints and components attached. An X-ray helps in checking the BGA assembly quality.
- If the PCB assembly requires components to be inserted via PTH technology, then it is done at this step. It may be carried out via designated machines or manually as per the requirement and suitability.
- Now, the PCB assembly is cleaned thoroughly to get rid of leftover flux or any pollutants. This step helps in increasing the long-term dependability of a PCB.
- Though one round of inspection has already been carried out by now, comprehensive quality control testing is still necessary. During the inspection round, solder joints are checked. However, during this quality check, the functioning of the PCB assembly is tested. Additionally, it is examined if the PCB works well under conditions like heat, humidity, etc.
Various types of PCB assembly equipment are used in carrying out the above-mentioned steps, such as solder paste printing machine, pick and place equipment, AOI machine, reflow oven, wave soldering equipment, X-ray machine., etc., Remember, a minor error at any step may lead to major functioning issues. Therefore, the PCB assembly process needs to be carried out with utmost precision and care. If you are looking for a reliable PCB assembly company, check the offerings of Viasion Technology Co. Ltd. With 16+ years of experience, the company excels in handling small to medium-scale PCB assembly projects.
PCB Assembly: Best Practices
Certified and reputed companies like Viasion Technology Co. Ltd. follow the best industry practices while offering various PCB-related services. These practices include:
While outsourcing any aspect of your business, smooth communication between the client and the outsourcing partner is quite essential for a long-term, satisfying partnership experience. Therefore, good companies always ensure timely and transparent communication at various stages of the process.
2. DFM check:
Design for Manufacturability refers to designing a prototype that is quick and economical to be manufactured on a large scale. It also ensures that the design works well under conditions like temperature change. Therefore, industry experts always conduct a DFM check to ensure that the PCB assembly is functional and suitable to be installed in practical applications. This process also helps reduce the manufacturing time and costs. Further, it enhances the quality of the product.
3. Experienced production team and advanced equipment:
PCB assembly is a very complex task. Only very experienced workers and engineers can do this job perfectly. Besides, advanced equipment really helps to produce sophisticated products, such as highly precise pick and place equipment, automated solder paste printing machines, ten temperature zone reflow ovens., etc.
4. Automated inspection, manual inspection, X-ray inspection:
The entire functioning of an electronic device may fail due to a minor error in the PCB. Hence, no negligence should be there while performing various tests and quality checks. To ensure that the PCB is errorless and works flawlessly, good companies perform several inspection rounds, including manual and automated AOI inspections and X-ray inspections.
5. Thermal management and environmental considerations:
No matter how many precautions are taken, some devices are prone to getting heated up. This may affect the functioning of the PCB assembly. Therefore, features like thermal vias and heat sinks are included to manage such situations. Also, industry experts make sure that they take environmental conditions, like dust and moisture, into account while building a PCB assembly. Good companies take measures to manage such conditions.
Proper detail-oriented documentation is necessary to keep a record of the design and testing of the PCB assembly. This also helps in tracing errors and components at a later stage.
7. Upskilling and training of workers:
Experienced manufacturers know that the industry trends and requirements keep changing in the current times of technological advancements. Therefore, it becomes essential to keep training the workforce and upskill them continuously. This helps them stay updated with the latest trends and perform beyond expectations.
The Bottom Line
PCB assembly plays a pivotal role in the functioning of most electronic devices. Therefore, if you are looking for a company to outsource your PCB manufacturing and assembly process, research thoroughly. Do not slack while running this research as the company you decide to partner with can make or break your entire project. Prefer experienced companies like Viasion Technology Co. Ltd. for a smooth experience and high-quality PCBs.