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PCB Assembly FAQ

How To Ensure The Quality of PCB Assembly Processing


With the rapid development of electronic technology, printed circuit boards are the basic components of electronic equipment. The quality of PCB assembly and processing is becoming more and more stringent, and customers have higher and higher requirements for product life cycle control and traceability. PCB assembly is a board after all components are welded and installed on the board. It is an assembly process of PCB + electronic components. This process involves many steps and links to achieve high-quality and stable production of PCB circuit boards and ensure the quality of PCB assembly and processing.

1. Printed Circuit Board Assembly And Processing Process  

Components Procurement and Preparation  

Purchase the required electronic components, including resistors, capacitors, transistors, integrated circuits, etc.

● Solder Paste Printing

A steel mesh made of thin metal sheets is placed on the board. This ensures that solder paste is only applied to the area where the component is to be mounted. After applying the solder paste, remove the stencil from the board.

PCB Fabrication

Transfer the circuit board design to a physical board with conductive paths and connection points. This can be achieved through printing, etching, drilling and other processes.

● PCB Assembly Technology

Once the PCB is manufactured, placement of components onto the circuit board begins. This is usually divided into two steps: surface mount technology (SMT) and plug-in mount technology (DIP).

· SMT: Mounted on PCB board by soldering or pasting components. The production process includes PCB board positioning, solder paste printing, SMT placement, reflow oven, and finished product inspection.

· DIP: First use the leads on the component to insert into the hole on the printed circuit board (PCBA), and then solder to the pad on the opposite side by manual assembly or using an automatic insertion mounting machine.

● Welding

After the components are mounted, they need to be soldered to ensure they are securely connected to the PCB board. Welding can use hot air stove, wave soldering, manual soldering and other methods.

· In surface mount PCB assemblies, perform reflow soldering. In this case, the PCB is passed through an oven heated to a temperature of 500°F. The solder paste melts and settles with the component as it cools.

· In through-hole components, perform wave soldering. In this case, the PCB with the components mounted on it moves on the hot wave soldering fluid. This liquefies the solder ball, which then solidifies as it cools to room temperature.

● Cleaning Circuit Board

After soldering is complete, clean the circuit board to remove any residue produced during the soldering process. Additionally, circuit boards are sometimes coated with a protective coating to increase their durability and stability.

● Checking and Testing

Inspection is required at all stages of the PCBA process to ensure quality and performance meet requirements. Inspections can include visual inspection, automated optical inspection (AOI), X-ray inspection (X-ray), functional testing, etc.

● Packaging and Shipping:

Packaging is usually selected based on the characteristics of the product and transportation requirements to ensure that it is not damaged during transportation.   

Printed circuit board assembly process

2. Quality Control and Testing

● Inspection Equipment  

· Appearance Automatic Inspection Machine: a device that conducts comprehensive, efficient and accurate inspection of the appearance of PCBA. Using advanced image processing algorithms, you can quickly capture and analyze PCB assembly appearance information, such as short circuits, open circuits, poor welding, etc. By comparing samples and standard images, comprehensive analysis and evaluation of PCBA appearance can be achieved.
· Automated Optical Inspection (AOI) System: uses cameras and image processing technology to inspect components, solder joints, printing quality, etc. on the surface of the circuit board assembly. 

· X-ray Inspection System (X-ray): The X-ray inspection system is used to check the quality of internal connections of PCBA boards, especially the integrity and accuracy of solder connections. It can detect hidden problems under welding, such as welding breaks, virtual welding, etc.

· Online SPI Device: Communicates with a microcontroller or other peripherals on the circuit board through a serial communication protocol. It is usually used for component programming, configuration, testing of digital and analog signals, communication interfaces, etc.

● Inspection Method

· Appearance/Manual Inspection: Check the position, direction of components, soldering conditions of pins, and printing quality on the PCB surface, etc. This method is only suitable for small batches of PCBs.
· Automated Optical Inspection (AOI): AOI machines have high-resolution cameras to accurately inspect and measure the height dimensions of devices on PCB assembly, and provide clear side-view images of ICs and various devices. During automatic detection, the machine automatically scans the PCBA through the camera, collects images, and compares the detected solder joints with qualified parameters in the database. After image processing, defects on the PCBA are inspected and displayed/marked via display or automatic marking.

· X-ray Inspection: Performed on complex PCB assembly designs with multi-layer component installation, it can not only meet the inspection of most SMT PCB, FPCB and other products, but also can detect BGA, CSP, packaged chips, LED, SMT welding, and small castings Check the welding quality of the package.

· Flying Probe Testing: It can quickly and accurately detect various defects and faults on printed circuit boards, find problems in time and make corrections, thereby improving the quality and reliability of PCBA products. 

· Functional Testing: Test whether the PCB assembly board works. This can cover a variety of tests, including analog signal testing, digital signal testing, communication interface testing, etc.

3. SCSPCBA Controls The Quality of PCB Assembly and Processing

● Quality Control  

Quality control is the core link in the PCB assembly and production process. SCSPCBA has established a complete quality inspection system to conduct strict quality inspection on raw materials, semi-finished products and finished products. In the raw material procurement process, SCSPCBA strictly controls the quality of raw materials to ensure that the quality of raw materials meets production requirements. During the PCBA production process, SCSPCBA regularly conducts quality inspections on semi-finished products to detect and deal with problems promptly to prevent substandard products from entering the next step. Before the PCB assembly finished products are put into storage, SCSPCBA conducts multiple quality inspections on each batch of PCBA finished products to ensure the product's qualification rate.

● Quality Management System  

SCSPCBA has also introduced a modern quality management system to ensure the standardization of the production process. Through these management systems, SCSPCBA can promptly discover and solve problems in the production process, continuously improve the production process, and improve the quality level of products.

● Employee Technology Improvement  

Focus on strengthening employee training and education to improve employees' quality awareness and operational skills. Through regular training and assessment, we ensure that employees are familiar with and master the quality standards and operating procedures, to strictly implement quality control measures in actual production.

● Quality Certificate  

· ISO certification

SCSPCBA has obtained ISO 9001 quality management system certification. The PCB assembly factory has established a quality management system that meets international standards and can continue to provide PCB products and PCBA services that meet customer needs and legal and regulatory requirements.

·IPC standard

SCSPCBA is IPC-A-600 and IPC-A-610 certified, allowing PCB assembly plants to ensure that their processes comply with industry standards.

· ROHS compliance certificate

SCS PCBA's PCB assembly factory already has ROHS compliance certificate, and PCBA products comply with relevant regulatory requirements.

· IATF 16949 certification

SCSPCBA has obtained quality management certification for its capabilities and compliance in PCBA assembly quality management in the automotive field.

4. Development Goals

As the complexity and sophistication of electronic production continue to increase, the deep integration of PCBA product assembly and testing automation has become SCSPCBA's core strategy to improve production efficiency and quality. This not only optimizes the efficiency of individual aspects of PCB assembly but also achieves comprehensive optimization of the PCBA production process. During the PCB assembly process, real-time testing, measurement and monitoring ensure that every step strictly complies with established standards and requirements, which not only significantly improves PCB assembly accuracy, but also ensures stable product quality.

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