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What is pcba?PCBA meaning printed circuit board assembly.PCBA is an important part of electronic circuit design. It is not just a simple printed circuit board (PCB), but electronic components (such as SMD components SMT and plug-in components DIP) mounted on the PCB board, and through welding and other processes to form a complete circuit system.
PCB VS PCBA:
PCB is the foundation of PCB assembly, while PCBA is the extension and expansion of PCB.
In the production of electronic products, PCB board and PCBA cooperate and depend on each other to achieve the function and performance of electronic products.
PCB and PCBA play an important role in the production of electronic products.、
PCB and PCBA differences in the ‘PCBA = PCB + Assembly’, that is, there is no assembly of electronic components of the board called PCB, and has been completely assembled up to the electronic components of the board is called PCBA.
PCBA is in fact ‘Printed Circuit Board Assembly’ of the English acronym, some people briefly called it PCA, of course, some people call it PWA (Printed Wire Assembly), Chinese we generally call it ‘assembled circuit boards’, ‘circuit assembly boards,’ or simply referred to as ‘assembly board’!
However, few people in the industry use the above Chinese to call the PCBA, generally if a whole machine only a board, it will be directly called ‘Main board (Main board)’ or directly omit to call ‘board’, if there are more than two pieces of PCBA, it will be called ‘PCBA’.
If there are more than two pieces of PCBA, it will use the function to distinguish the main board, IO board, charging board (charging board), display board (video card) to call them.
How are electronic components mounted on the PCB to form a PCBA?
The current mainstream PCB assembly process is ‘surface mount technology’ (SMT, Surface Mount Technology), the process begins with the printing of solder paste (Solder Paste) on the blank PCB, and then the electronic components are accurately mounted to the PCB surface. Subsequently, the PCB is heated by a reflow oven (Reflow Oven), the solder paste melts at high temperature, and the pins of the components are firmly soldered to the circuit board to achieve component fixation and electrical connection.
A small number of PCB assembly using ‘wave soldering’ (Wave Soldering) technology. Generally used for the installation of those larger, heavier or need to be inserted and removed several times and subject to greater mechanical stress of the electronic components. Such components if not fully realised surface mount (SMD) technology, or higher cost, or taking into account the customer's use of the durability of the demand, often using through-hole insertion (THD, Through Hole Devices), through the wave soldering machine will be soldered in the PCB through-hole components.
In addition, there are also processes combining SMT mounting and wave soldering technology, combining the advantages of the two, to complete the soldering of various electronic components on the PCB. In short, there are a variety of technical means can be soldered to the electronic components on the PCB to form a fully functional PCBA.
Common pcba electronic components
1. Resistors
Resistors are one of the most commonly used electronic components in PCBA, used to limit the amount of current in a circuit. According to the material. Structure and resistance value of different resistors can be divided into fixed resistors. Variable resistors and special resistors. Resistors are widely used in various circuits, such as power supply circuits. Amplifier circuits. Signal processing circuits, in order to achieve the regulation and control of current.
2. Capacitor
Capacitor is the storage of electric charge and electric energy components, with the isolation of DC. Through the characteristics of AC. In PCBA, capacitors are often used for filtering. Coupling. Tuning. Bypass and other circuits to improve the performance and stability of the circuit. According to the different structure and use, capacitors can be divided into fixed capacitors. Variable capacitors and fine-tuning capacitors.
3. Inductance
Inductors, also known as induction coils, have the function of storing magnetic energy. In a circuit, the inductor can prevent the change of current, play the role of filtering. Stabilise the current. Inductors are widely used in power supply filtering. Signal processing has a wide range of applications.
4. Diode
Diode is a one-way conductive electronic components, widely used in rectifier. Detection. Voltage regulator and other circuits. In the PCBA, diodes can achieve the circuit voltage regulation. Signal amplification and switching control and other functions. Common diodes are silicon diodes and germanium diodes, etc. Its performance parameters such as forward voltage drop. Its performance parameters such as forward voltage drop, reverse breakdown voltage, etc. determine its application scenarios.
5. Transistor
Transistor is a kind of electronic components with the function of amplification. Transistor is a kind of electronic component with the function of amplification, switching, etc. It is the core component of various circuits. In PCB circuit board assembly, transistors are often used in amplification circuits. Oscillation circuit. Switching circuits, in order to achieve signal amplification. Frequency conversion and circuit control. There are many types of transistors, including bipolar transistors. Field effect transistors, etc., each with its own characteristics, widely used in a variety of electronic equipment.
6. Integrated circuits
Integrated circuits are multiple electronic components integrated on a chip electronic components, with a small size. Low power consumption. Stable performance and other advantages. In PCB board assembly, integrated circuits are the key components to achieve a variety of complex functions, such as digital signal processing. Analogue signal processing. Communication interface, etc. Common integrated circuits are operational amplifiers. Logic gate circuits. Microprocessors, etc., widely used in a variety of intelligent devices and systems.
7. Sensors
Sensors can sense physical quantities or states in the environment and convert them into electrical signals for output. In PCBA, sensors are often used to detect temperature. Humidity. Light. Pressure and other parameters for the intelligent control of electronic devices to provide data support. There are many types of sensors with different performance, choosing the right sensor is crucial to improve the performance and user experience of electronic devices.
8. Triode
Triode, full name should be semiconductor triode, also known as bipolar transistor. Crystal triode, is a semiconductor device to control the current its role is to amplify the weak signal into a larger amplitude value of the electrical signal, also used as a non-contact switch. Triode is a semiconductor substrate on the production of two very close to each other PN junction, two PN junctions to the block of semiconductor is divided into three parts, the middle part of the base area, the two sides of the part of the emitting area and the collector area, the arrangement of PNP and NPN two kinds.
9. Transformer Transformer
Transformer (Transformer) is the use of the principle of electromagnetic induction to change the AC voltage device, the main components are the primary coil, secondary coil and iron core (core).
The PCBA manufacturing process includes the following major steps:
Component Procurement: Procure components according to the BOM (Bill of Materials) list.
Patch and plug-in: the use of SMT (Surface Mount Technology, surface mount technology) and THT (Through-Hole Technology, through-hole insertion technology) will be installed on the PCB components.
Soldering: Reflow soldering or wave soldering to connect the components to the PCB electrically.
Testing: Functional testing and quality inspection of the assembled PCBA to ensure that the product works properly.
Cleaning and Packaging: Remove the flux residue generated during the soldering process and finally package.
PCBA process is simply understood as the integration of SMT and DIP processes. According to different production technology requirements, it can be subdivided into single-side SMT mounting process, single-side DIP insertion process, single-side mixing process, single-side mounting and insertion hybrid process, double-sided SMT mounting process and double-sided mixing process.
PCBA process includes carrier board, printing, placement, reflow soldering, insertion, wave soldering, testing and quality inspection, etc. The specific process can refer to the following PCBA process flow chart.
Different types of PCB boards, there are many differences in the process, the following details of their respective characteristics.
Single-sided SMT mounting: first add solder paste on the component pad, complete the PCB bare board solder paste printing, through the reflow soldering mounting related electronic components, and then finally reflow soldering. This process is like giving the PCB board carefully ‘dressed’, each component is precisely placed in their own ‘nest’.
Single-sided DIP insertion: For PCB boards that require insertion, production line workers will first insert electronic components, and then over the wave soldering for welding and fixing, and finally cut the feet to wash the board. However, the productivity of wave soldering is relatively low.
Single-sided mixed assembly: the first PCB board for solder paste printing, mounting electronic components after the reflow soldering fixed, completed after the quality inspection for DIP insertion, after which you can choose to wave soldering welding or manual welding. If there are fewer through-hole components, manual soldering is a good choice.
Mixed single-sided mounting and insertion: Some double-sided panels will be mounted on one side and inserted on the other. The process of mounting and inserting is similar to single-sided processing, but it requires the use of fixtures to assist in reflow and wave soldering of PCB boards.
Double-sided SMT mounting: Some PCB design engineers will use double-sided mounting in order to balance the aesthetics and functionality. For example, IC components are arranged on the A side, and chip components are mounted on the B side, which can make full use of the space of the PCB board and minimise the area of the PCB board.
Double-sided mixed assembly: double-sided mixed assembly has two ways. The first way of PCB assembly requires three times heating, efficiency is not high, and the use of red glue process wave soldering qualified rate is low, not recommended. The second way applies to double-sided SMD components more, THT components are very few cases, it is recommended to use manual welding; if THT components more, it is recommended to use wave soldering.
PCBA testing is a key step to ensure the quality of production and delivery, which determines whether the final performance of the product is up to standard. Its purpose is to catch the assembly of poor circuit boards, through the simulation of circuit boards actually installed into the machine when the full-featured test, with a view to catching in the assembly of the machine before the assembly of all possible defects in the circuit assembly boards to catch out, to avoid the assembly of the whole machine only to find out that the bad, but also to dismantle the restructuring of the whole caused by a waste of man-hours and the loss of materials.
PCBA testing mainly includes ICT testing. Aging test. Harsh environment test and fatigue test.
1.ICT that is, automatic in-line test, is a modern PCB manufacturers must test equipment. It is mainly through the test probe contact PCB layout (generally refers to the PCB design) out of the test point to detect the PCB board assembly line open. Short circuit. All parts of the fault situation, and clearly inform the staff. ICT use a wide range of measurement accuracy is high, the problem detected on the instructions of a clear, even if the general standard of electronic technology workers to deal with the problem of PCBA is also very easy. The use of ICT can greatly improve productivity and reduce production costs.
2.FCT (Function Test) it refers to the test PCBA board to provide a simulated operating environment, so that it works in a variety of design states, so as to obtain the parameters of each state to verify the function of the PCBA board good or bad test methods.
3. Aging test refers to the simulation of the product in the reality of the use of various factors involved in the aging of the product to carry out the corresponding conditions to strengthen the test process. PCBA boards can be based on a long period of power test to simulate the use of customers, the input / output test to ensure that its performance to meet market demand. Under special circumstances, the PCB board assembly also needs to be exposed to a specific temperature and humidity environment.
4. Harsh environment testing is mainly to expose the PCBA board to extreme values of temperature. Humidity. Drops. Splash. Vibration, to obtain a random sample of the test results, so as to infer the reliability of the entire batch of PCB circuit board assembly.
5. Fatigue test is mainly a sample of PCBA boards, and the function of high-frequency. Prolonged operation, observe whether the failure, judge the probability of failure test, so as to provide feedback on the performance of the PCBA within the electronic product.