SMT PCB Assembly

ELE PCB – Professional SMT PCB Assembly Factory

ELE PCB is able to finish almost any SMT assembly and wave soldering works, with 7 SMT line working all the day for 24 hours to make sure customer’s product boards can come out quickly. Get a free quote today!



Introduction to SMT PCB Assembly

Surface Mount Technology (SMT) is a method used for attaching electronic components directly to the surface of a Printed Circuit Board (PCB). SMT has significantly transformed the electronics industry by enabling the production of more compact, lightweight, and efficient electronic devices. SMT PCB Assembly is the process of creating PCBs by placing and soldering surface-mount components onto the PCB.

Figure 1:Example of SMT Assembly
Figure 1:Example of SMT Assembly

In contrast to traditional through-hole assembly, where components are mounted on the PCB by inserting their leads through holes, SMT components are directly soldered onto copper pads on the surface of the board. This eliminates the need for drilling holes, allowing for a higher density of components and improved electrical performance.

The SMT Process

Why choose ELE? Because we value our product quality more than our customers. The product will not be sent out until it has passed through multiple quality inspection processes. And customers can come to our factory to visit at any time to ensure the quality of service. The following chart is the quality control process of ELEPCB.

The SMT PCB Assembly process is a series of interconnected stages that ensure the precise placement and soldering of surface-mount components onto a PCB. Each step is crucial in maintaining the overall quality and performance of the final product. The main stages of the SMT process are as follows:

The SMT PCB Assembly process comprises various steps, including:

  • Designing the PCB layout

The first stage in the SMT process is designing the PCB layout using specialized software. This involves determining the optimal placement of components, routing, and power distribution, while adhering to industry standards and design rules. The PCB layout serves as a blueprint for the entire assembly process, guiding the placement of components and the routing of electrical connections.

  • Preparing the SMT Stencil

In parallel with the PCB design, an SMT stencil is prepared to facilitate the accurate application of solder paste onto the PCB pads. The stencil is a thin sheet of metal (usually stainless steel) with precisely cut openings corresponding to the solder pads on the PCB. During the assembly process, the stencil is aligned with the PCB, and solder paste is spread across its surface using a squeegee.

  • Placing the components

During the component placement stage, surface-mount components are placed on the PCB using specialized pick-and-place machines. These machines can accurately place thousands of components per hour, ensuring rapid assembly.

SMT Component placing
Figure 2: SMT Component placing
  • Soldering 

After component placement, the PCB is passed through a reflow oven, where the solder paste melts and forms a secure bond between the components and the PCB.

  • Inspection and Testing 

The assembled PCB is subjected to various inspection and testing processes, such as Automated Optical Inspection (AOI) and X-ray inspection, to ensure the quality and functionality of the board. Quality control is an essential aspect of the SMT PCB Assembly process, ensuring that the final product meets the desired performance and reliability standards. Various inspection and testing methods are employed throughout the assembly process, including:

  • Automated Optical Inspection (AOI)

AOI is a non-contact inspection method that uses high-resolution cameras and advanced image processing algorithms to detect defects in the assembled PCB, such as missing, misaligned, or damaged components, and soldering issues like insufficient solder or bridging.

  • X-ray Inspection

This technique is used to inspect the solder joints of components that are not visible to the naked eye, such as those in Ball Grid Array (BGA) packages. X-ray inspection allows for the detection of soldering defects, such as voids or insufficient solder, ensuring the reliability of the assembled PCB.

  • In-circuit Testing (ICT) and Functional Testing

These tests are performed on the fully assembled PCB to verify its electrical functionality and compliance with design specifications. ICT involves testing individual components and connections, while functional testing evaluates the overall performance of the PCB in its intended application.

By following a rigorous SMT process with strict quality control measures, PCB manufacturers like ELE PCB Ltd. can deliver high-quality, reliable, and efficient PCBs for a wide range of applications. ELE PCB Ltd., with its vast experience in PCB and PCBA manufacturing, is well-equipped to handle SMT PCB Assembly for a wide range of applications, offering clients high-quality, reliable, and efficient solutions for their electronic device needs.

  • SMT Machine for PCB Assembly

The SMT machine plays a critical role in automating the assembly process, ensuring high accuracy, speed, and consistency.

There are two main types of SMT machines used in PCB assembly:

  • Pick-and-Place Machines

These machines pick up surface-mount components from their storage containers (usually tapes or reels) using a vacuum nozzle, align them with the PCB pads, and place them on the solder paste. Advanced pick-and-place machines can handle a wide range of component sizes and types and can place thousands of components per hour.

  • Reflow Ovens

After the components have been placed on the PCB, the board is passed through a reflow oven, where the solder paste is heated to its melting point, allowing it to flow and form a secure bond between the components and the PCB. The reflow oven’s temperature profile is carefully controlled to ensure consistent soldering without damaging the components or the PCB.

SMT Assembly machine
Figure 3: SMT Assembly machine

SMT Components and Packaging

SMT components come in various types, sizes, and packaging styles, enabling the assembly of a wide range of electronic devices.

This section provides an overview of the most common SMT components and packaging styles used in the electronics industry.

  • Passive Components

Passive components are essential building blocks in electronic circuits, and they do not produce energy or amplify signals. The most common passive SMT components include:

  1. a) Resistors:SMT resistors are used to limit current flow, divide voltage, and set signal levels in electronic circuits. They come in various sizes, such as 0603, 0805, and 1206, which refer to their dimensions in hundredths of an inch (e.g., 0603 resistors measure 0.06 x 0.03 inches).
  2. b) Capacitors:Capacitors store and release electrical energy and are used for filtering, coupling, decoupling, and energy storage applications. Like resistors, SMT capacitors come in various sizes, including 0603, 0805, and 1206.
  3. c) Inductors:Inductors are passive components that store energy in their magnetic field and oppose changes in current. They are commonly used in filters, transformers, and power supply circuits.
  • Active Components

Active components can control the flow of current and amplify signals. They play a crucial role in electronic devices and come in various packaging styles. The most common active SMT components include:

  1. a) Transistors:Transistors are semiconductor devices used for amplification, switching, and voltage regulation. They come in a variety of SMT packages, such as SOT-23, SOT-223, and SOT-89.
  2. b) Integrated Circuits (ICs): ICs are compact electronic devices that contain multiple transistors, resistors, capacitors, and other components on a single semiconductor chip. SMT ICs are available in various package types, including Quad Flat No-Lead (QFN), Small Outline Integrated Circuit (SOIC), and Ball Grid Array (BGA).
  • Component Packaging Styles

SMT components are available in various packaging styles to suit different applications and assembly requirements.

Assembly machines 1
Figure 4: Assembly machines

Some of the most common SMT packaging styles include:

  1. a) Chip packages:Chip components, such as resistors, capacitors, and inductors, are the simplest SMT packages. They consist of a rectangular or square body with metal terminations on either end.
  2. b) Leadless packages:Leadless components, such as QFN and DFN ICs, have metal pads on their bottom surface for soldering directly onto the PCB. These packages offer a compact footprint and improve thermal performance.
  3. c) Lead frame packages:Lead frame components, such as SOIC and SOT transistors, have leads that extend from the body and are soldered onto the PCB. These packages provide a balance between ease of assembly and component size.
  4. d) Ball Grid Array (BGA) packages:BGA components have an array of solder balls on their bottom surface for soldering onto the PCB. This packaging style allows for a high density of connections in a small footprint, making it suitable for advanced ICs with numerous pins.

Understanding the various types of SMT components and packaging styles is crucial for the successful design and assembly of modern electronic devices. ELE PCB Ltd., with its extensive experience in SMT PCB Assembly, has the expertise to handle a wide range of components and packaging styles, ensuring the production of high-quality, reliable, and efficient PCBs for various applications.

Advantages of SMT PCB Assembly

SMT PCB Assembly has gained widespread popularity in the electronics industry due to the numerous advantages it offers over traditional through-hole assembly methods. SMT PCB Assembly offers numerous advantages over traditional through-hole assembly, including smaller and lighter devices, improved performance due to reduced parasitic effects, cost-effectiveness, and faster assembly times. As a result, SMT has become the dominant assembly method for modern electronic devices, ranging from smartphones and laptops to advanced automotive and aerospace systems.

A typical SMT PCB 1 1
Figure 5: A typical SMT PCB

The key benefits of SMT PCB Assembly include space efficiency, improved performance, cost-effectiveness, and faster assembly times. These advantages are discussed in detail below:

  • Space Efficiency

One of the most significant advantages of SMT PCB Assembly is the efficient use of space on the PCB. SMT components are smaller and can be placed directly onto the surface of the board, eliminating the need for drilling holes for component leads. This allows for a higher density of components and more complex circuit designs within a smaller area, contributing to the miniaturization of electronic devices.

  • Improved Performance

SMT PCB Assembly offers better electrical performance compared to through-hole assembly. The shorter electrical paths between components result in reduced parasitic effects, such as capacitance and inductance, leading to faster signal propagation and improved overall performance. Additionally, the lower mass of SMT components makes them less susceptible to mechanical vibrations, further enhancing the reliability of the assembled PCB.

  • Cost-Effectiveness

SMT PCB Assembly is more cost-effective than through-hole assembly due to several factors. First, the smaller size of SMT components typically results in lower material costs. Second, the elimination of drilling holes for component leads reduces manufacturing time and costs. Finally, the automation of the SMT process using advanced pick-and-place machines and reflow ovens allows for higher production rates and reduced labor costs, contributing to a more cost-effective assembly process.

  • Faster Assembly Process

The SMT PCB Assembly process is faster than traditional through-hole assembly, primarily due to the high level of automation involved. With the use of advanced pick-and-place machines and reflow ovens, PCB manufacturers can achieve rapid assembly times, enabling them to meet tight production schedules and deliver products more quickly to the market.

In summary, SMT PCB Assembly offers numerous advantages over traditional assembly methods, making it the preferred choice for modern electronic devices. With its efficient use of space, improved performance, cost-effectiveness, and faster assembly times, SMT PCB Assembly has become the industry standard for assembling high-quality, reliable, and efficient PCBs. ELE PCB Ltd., with its expertise in SMT PCB Assembly, is well-positioned to deliver these benefits to its clients across various industries.


In conclusion, Surface Mount Technology (SMT) PCB Assembly has revolutionized the electronics industry by offering numerous advantages such as space efficiency, improved performance, cost-effectiveness, and faster assembly times. ELE PCB Ltd. is a trusted supplier of high-quality SMT PCB Assembly services, backed by their extensive experience, cutting-edge technology, comprehensive services, and commitment to customer satisfaction. As a one-stop solution for all your PCB and PCBA needs, ELE PCB Ltd. ensures that you receive the best possible products and services for your specific requirements. Don’t hesitate to contact ELE PCB Ltd. for all your SMT PCB Assembly needs and experience the benefits of partnering with a reliable and professional PCB manufacturer.

ELE PCB Ltd.: Your Trusted SMT PCB Assembly Supplier

ELE PCB Ltd. has built a reputation as a leading provider of high-quality and reliable SMT PCB Assembly services. With over a decade of experience, state-of-the-art facilities, and a commitment to excellence, ELE PCB Ltd. is the ideal partner for all your SMT PCB Assembly needs. The following subheadings delve into the various aspects that make ELE PCB Ltd. stand out as a trusted SMT PCB Assembly supplier:

  • Expertise and Experience

ELE PCB Ltd. has extensive experience in providing SMT PCB Assembly services for various industries, including automotive, aerospace, medical, and consumer electronics. Their team of skilled engineers and technicians has the expertise to design and manufacture PCBs that meet the unique challenges and requirements of these industries, ensuring that the final products meet the highest standards of quality and performance.

  • Advanced Technology and Equipment

ELE PCB Ltd. utilizes cutting-edge technology and equipment to ensure the quality and reliability of its SMT PCB Assembly services. By employing advanced PCB design software, automated assembly equipment, and sophisticated inspection and testing systems, ELE PCB Ltd. can consistently deliver PCBs that meet the highest standards of quality and accuracy.

  • Comprehensive Services

ELE PCB Ltd. offers a wide range of PCB and PCBA services to meet the diverse needs of its clients. These services include PCB prototyping, PCB assembly, and PCB fabrication for various types of PCBs, such as Multilayer PCBs, Rogers PCB, HDI PCB, MCPCB, Flex PCB, and Rigid Flex PCBs. ELE PCB Ltd.’s comprehensive services make it a one-stop solution for all your PCB and PCBA requirements.

  • Quality Certifications

ELE PCB Ltd. holds several industry certifications, including ISO9001:2015, ISO13485:2016, ROHS, and FCC. These certifications attest to ELE PCB Ltd.’s commitment to maintaining the highest standards of quality and reliability in its products and services. By choosing ELE PCB Ltd. as your SMT PCB Assembly supplier, you can be confident that you are partnering with a company that values quality and customer satisfaction.

  • Customer Support and Engagement

ELE PCB Ltd. prides itself on its exceptional customer support and engagement. The company works closely with its clients to develop custom PCB and PCBA solutions that meet their specific needs, providing guidance and support throughout the design, manufacturing, and testing processes. ELE PCB Ltd.’s commitment to customer satisfaction ensures that clients receive the best possible service and a product that meets their expectations.

To learn more about ELE PCB Ltd.’s SMT PCB Assembly services or to request a quote, don’t hesitate to contact their friendly and knowledgeable team. They are always eager to discuss your project requirements and provide expert advice to help you achieve the best possible results. 


1. Contact ELE PCB Ltd. for your SMT PCB Assembly Needs

If you are looking for a reliable and experienced SMT PCB Assembly supplier, look no further than ELE PCB Ltd. With a proven track record of delivering high-quality, custom PCB and PCBA solutions, ELE PCB Ltd. is ready to assist you with your next project. To discuss your specific requirements, obtain a quote here, or learn more about our services here, don’t hesitate to reach out to the ELE PCB Ltd. team. Our knowledgeable staff is eager to help you achieve the best possible results for your electronic devices.


ELE PCB has got the IS09001:2015, IS013485:2016, ROHS and FCC certifications. We can offer all kinds of services, including PCB manufacturing and PCB assembly, sample orders and batch orders. For PCB assembly, utilizing 7 high-speed SMT PCBA lines from Yamaha and Sony, to meet our customers’ needs. Our extended services include PCB design &PCB Layout, hardware design engineering, firmware &software development, and personalization. ELE company is honored as an excellent supplier from any company all around the world. We deeply believe that our good service and experience will completely meet your needs. Integrality, value and innovation are the forces that drive our success.



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