PCBA (Printed Circuit Board Assembly) is the process of assembling electronic components onto a blank PCB board. This guide will provide you with a thorough understanding of the PCBA manufacturing process, from prototyping to mass production, ensuring you are well-informed about each step involved.
PCB Prototyping
Before mass production can begin for any product, it is essential to create prototypes to identify potential issues and develop solutions. Here are the detailed steps involved in PCB prototyping:
BOM and Gerber File Verification:
The Bill of Materials (BOM) and Gerber files contain a list of all components required for PCB assembly. It is crucial to verify the accuracy of these materials before the prototyping process starts. Experienced engineers meticulously examine the board design, component samples, and BOM to ensure everything is correct before initiating assembly.
PCB and SMT Stencil Manufacturing:
For one-stop PCB assembly, the manufacturing company also produces the PCBs. During this stage, Surface Mount Technology (SMT) stencils for PCB assembly are manufactured. The duration of PCB production depends on the complexity of the circuit boards. These stencils are vital as they help in the precise placement of solder paste on the PCB.
PCBA First Piece Testing:
A comprehensive test is performed on the first assembled board to ensure that all functions are normal. If issues are identified, engineers address them promptly. Various testing equipment is used during this process, and a detailed testing report is provided upon completion. Assuming all tests are normal, batch production can commence following customer approval.
PCBA Mass Production Manufacturing Steps
Once the prototyping phase is successfully completed, the process moves into mass production. The steps involved in PCBA mass production are as follows:
Programming and Adjusting the Bonder:
According to the sample BOM and patch location map provided by the customer, the coordinates for the placement of the components are programmed. The process involves creating a program based on the customer’s SMT patch processing information for the initial piece.
Printing Solder Paste:
Solder paste is printed onto the PCB pads using a stencil, which is necessary for the soldering of SMD (Surface-Mount Device) components. This step is performed by a screen printing machine, positioned at the front of the SMT production line. Accurate solder paste application is crucial for the quality of the final assembly.
SPI (Solder Paste Inspection):
The SPI machine checks if the solder paste's thickness and shape meet the required standards. Standard solder paste thickness ranges from 0.09mm to 0.15mm, and it must completely cover the PCB pads. The SPI machine ensures that the solder paste application is qualified for PCB assembly.
Patching:
Electronic SMD components are accurately mounted on the fixed positions of the PCB using a mounting machine. This equipment is placed right after the screen printing machine in the SMT production line. There are two types of SMD machines:
High-speed machine: Used for components with large and small pin pitches.
General-purpose machine: Used for components with small pin pitches and larger volumes.
High-Temperature Solder Paste Melting:
The solder paste is melted and cooled to firmly weld electronic components to the PCB. This process, known as reflow soldering, is carried out in a reflow oven, positioned behind the placement machine in the SMT production line.
AOI (Automated Optical Inspection) Testing:
After reflow soldering, PCBAs go through an AOI machine. A camera automatically scans the PCBA, and the AOI machine collects images, comparing the tested solder joints with the database parameters. It identifies defects on the PCB through image processing and marks them on the screen. A quality control technician then marks the defects on the circuit boards for maintenance.
Through-Hole (PTH) Assembly:
PTH assembly involves mounting PTH components on PCBAs. PTH components have longer pins than SMDs, which go through the PCB through-holes. This operation is usually performed manually and is relatively simple compared to SMT assembly.
Wave Soldering:
Following PTH assembly, wave soldering fills the space between PTH pins and the PCBA, connecting the PTH components tightly. The PCBAs are pre-heated and then passed through a wave soldering oven, where liquid tin fills the space between the PTH pins and the PCBA. The tin cools and solidifies, ensuring a firm connection.
Visual Inspection:
A manual inspection focuses on verifying version changes, the use of specified materials, the correct orientation of directional components (such as ICs, diodes, transistors, capacitors, and switches), and checking for welding defects like short circuits, open circuits, false parts, and false welding.
PTH Rework:
This step mainly involves trimming the pins of products that are too long. Technicians trim the PTH legs to 1-2mm and use a soldering iron to repair any areas not properly soldered.
PCBA Function Test:
The assembled PCBA undergoes a functional test using a PCBA function tester. This test evaluates the product’s current, voltage, capacitance, and other critical parameters to ensure they meet the specifications.
Thermal Aging Test:
PCBAs are placed in a thermal chamber, powered on for about 250 hours without interruption, following the ECIA – EIA-364-17 standard. This test ensures the reliability and durability of the PCBAs.
Packaging:
Tested products are packed using anti-static materials like bubble bags, static cotton, and blister trays. Packaging methods include using anti-static bubble bags or custom-designed blister trays, depending on the sensitivity of the SMD components.
Innovations and Trends in PCBA
Advanced Material Usage
Flexible PCBs: These PCBs are designed to be flexible, allowing for the creation of more compact and versatile electronic devices.
Robotic Assembly: Automation in PCB assembly reduces errors and increases production speed. Robots can place components with extreme precision.
AI and Machine Learning: These technologies are increasingly being used to predict failures and optimize production processes.
Quality Control Enhancements
Enhanced AOI Systems: Modern AOI systems use advanced imaging technologies and AI to detect even the smallest defects.
In-Line Testing: Continuous testing during production helps identify and rectify issues in real-time, improving the overall quality of the final product.
Sustainability Efforts
Eco-friendly Materials: There is a growing trend towards using environmentally friendly materials in PCB manufacturing.
Energy-efficient Processes: Innovations aim to reduce the energy consumption of PCB manufacturing, making the process more sustainable.
A suitable PCBA manufacturer has advanced equipment and an experienced technical team to ensure all electronic components are accurately assembled on the PCB. This not only enhances product performance but also reduces failure rates.
Strict Quality Control
Reliable manufacturers implement stringent quality control measures, including Automated Optical Inspection (AOI), functional testing, and thermal aging tests, ensuring each PCBA meets specifications and performance requirements.
Reduced Production Costs
Experienced manufacturers as HuaXing can optimize production processes, improving efficiency and reducing production costs. They can obtain better prices through bulk purchasing of components and materials, thus saving costs.
If you have PCBA manufacturing and processing needs, HuaXing is an excellent choice. We offer one-stop PCB manufacturing and processing services for various fields, including intelligent devices, medical products, aerospace, and military applications. Our PCBA manufacturing services are available to customers worldwide, ensuring high-quality and reliable products.
By partnering with us, you gain access to cutting-edge technology, expert engineering support, and a commitment to excellence that ensures your products meet the highest standards. Contact us today to learn more about how we can assist with your PCBA needs and help bring your innovative products to life.
At Huaxing PCBA Factory, we pride ourselves on our commitment to providing PCBA solutions that consistently meet and exceed the highest industry standards. Our strong Quality Management System (QMS) is the cornerstone of our operations, ensuring that every product leaving our facility is of the highest quality.
