SMT PCB Assembly


Surface Mount Technology (SMT) is the most popular technology and process in the electronic assembly industry that enables manufacturers to produce modern devices with smaller footprints. The technique lends itself to miniaturization of assemblies, which is the order of the day. SMT can be highly automated, so it is a preferred choice for clients who need circuit boards in high volume, but it’s also highly customizable.

KingFord is an experienced and reliable SMT PCB assembly supplier which provide complete PCB assembly services for small and medium batch projects from PCB design, DFMA analysis, PCB manufacturing, SMT placement, to terminal DIP plug-ins. With automated SMT Assembly process our boards ensure optimal performance in the most challenging applications.

SMT PCB Assembly Process

1. Preparing the PCB and Initial Circuit Board Design

Assemblers use a solder paste printer to place solder paste in the desired location on each board before adding components to the board. Solder paste is a mixture of solder particles and a special flux. Heating this solder paste during reflow causes electrical connections to form. Manufacturers often use stencils and squeegees to ensure that solder paste is printed in the correct location on each circuit board. Jet printing is another option for prototype PCB assembly.

Preparing the PCB and Initial Circuit Board Design

2. Placing Surface Mounted Components Components

After applying solder paste and inspecting it, the assembler carefully places the components on the board. Typically, these components are packaged in trays, reels, or tubes so that pick-and-place machines can use vacuum or gripper nozzles to pick up the components and position them on the flex PCB.

Placing Surface Mounted Components Components

3. Reflow Soldering Process

The solder paste temporarily holds the components in place, but the electrical components are not fully attached to the unit, and electrical connections are not made until the PCB layout has been reflowed. In a reflow oven, the units are heated until the solder paste reaches a temperature high enough to form solder joints. This process needs to be carefully controlled, as the maximum temperature of the assembly may be close to that required to produce an acceptable solder joint.

Reflow Soldering Process

4. Inspection

Quality assurance inspection can take place at a couple of key moments in the SMT process, depending on the equipment used and the design requirements. Before components are attached, the solder paste is typically inspected to ensure there are no printing defects. Inspection is also common before and after reflow soldering.


Advantages of SMT PCB Assembly

1. Using SMT technology to assemble the components onto the board directly helps to reduce the entire size and the weight of the PCBs. This assemble method allows us to place more components in a restricted space, which can achieve compact designs and better performance.
2. Because of the automation, SMT technology ensures the reliability and consistency of the PCBs.
3. SMT assemble usually realizes through automatic machines to reduce manual steps during SMT processes, which significantly improves the production efficiency and lower the labor costs in the long-run.

pcb assembly team
Yamaha placement machines
SMT placement production lines

Professional SMT PCB Assembly Supplier

Delivery on time

We own a 4,000 square meters workshop, and are equipped with 7 fully automatic SMT placement lines and 2 DIP assembly lines. whether you are looking at a full production run or SMT PCB prototypes, you are assured of are quick turnaround times.

Quality Assurance

We are equipped with online SPI, AOI, and X-Ray testing equipment, and the product delivery pass rate can reach 99.5%, in line with ISO, IATF, and UL standards.

Strong supply chain and engineering team

The major advantage that we bring to the table is our competent team of engineers who have the necessary experience and expertise in doing justice to your Surface Mount (SMT) PCB Assembly.

Professional customer service team

We have a complete and user-friendly pre-sales and post-sales management system, which can quickly and comprehensively respond to the individual needs of customers, and provide customers with technical support, production operations and order services 24 hours a day.


Q: What is SMT assembly PCB
A: Surface mounting is a way to produce electronic circuits by placing components directly onto the board’s surface. SMT assembly is an alternative to the through-hole method of PCB manufacturing, which had its heyday in the 1970s and 1980s.

Q: What is SMT stencil
A: A surface mount technology (SMT) stencil may also be called a PCB stentcil, solder paste stencil, or laser stencil. An SMT Stencil's main purpose is to simply transfer the solder paste to a bare circuit board.

Q: What is the difference between SMT and SMD
A: The difference between SMD and SMT is that SMD (surface mount device) refers to an electronic component mounted on a PCB. In contrast, SMT (surface mount technology) relates to the method used to place electronic components on a printed circuit board.

Q: Do you support BGA component Assembly?
A: Yes, we do.

Q: What are your testing protocols for surface mount assembly?
A: Our testing protocols for Surface Mount Assembly include:Automated Optical Inspection, X-ray testing, In-circuit Testing and Functional Testing.

Q: Can you provide SMT printed circuit boards as per our custom requirements?
A: If you need circuit boards assembled to meet unique requirements, Yes, we provide SMT PCB assembly according to your special requirements.

Q: Where are SMT PCBs used?
A: SMT is used almost exclusively for the PCB assembly and manufacture these days.

Q: What is difference between SMT & through-hole components?
A: Through-hole components are best used for high-reliability products that require stronger connections between layers. Whereas SMT components are secured only by solder on the surface of the board, through-hole component leads run through the board, allowing the components to withstand more environmental stress.

Q: What files and documents are required for my PCB SMT assembly order?
A: Gerber Files, Bill of Materials and Component Placement or Pick & Place File.

Q: Can Manual Soldering be used in SMT printed circuit board assembly process?
A: Yes, a combination of both manual soldering and automated soldering can be used.

Q: Is SMT cheaper than through-hole?
A: SMT devices are very small, faster to place, and can be mounted on both sides of a PCB, making SMT boards much cheaper to manufacture.

Q: What are the advantages of Surface Mount (SMT) PCB Assembly?
A: SMT PCB come with a wide range of advantages, the most important ones being the fact that they are suited for printed circuit boards which offer small size and reduced weight.

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