SMT assembly

What is SMT assembly?

SMT is the abbreviation of surface mounting technology, which is called surface mounting or surface mounting technology. It is the most popular technology and process in the electronic assembly industry. SMT assembly has a wide range of applications. It is an alternative to the through-hole method of PCB assembly. This is a method to produce electronic circuits by placing components directly on the surface of the circuit board, allowing the components to be directly mounted on the surface mount PCB. This technology can make components small and convenient, so it is famous for its high mechanical strength. If you want high-speed circuit, SMT printed circuit board will be the first choice of you.

What are the advantages of surface mount technology?

Some of the advantages of SMT assembly include: affordability, compact design, efficiency, simplicity, less error-prone, etc. The details are as follows:

Affordability:
The most obvious feature of SMT assembly is the reduction of manufacturing costs. Compared with through hole technology, SMT assembly technology only needs to drill fewer holes on the circuit board. This significantly reduces the cost of processing and disposal. Therefore, SMT is more capable of mass production and has better unit cost. Rapid SMT assembly can be achieved.
Compact design:
Another advantage of SMT assembly is that it allows more components to be placed together more closely on the circuit board, so as to achieve smaller PCB design and make the design more compact. Widely used in HDI PCB circuit board assembly.
Efficiency:
In addition to making more efficient use of space on PCBs, SMT assembly is faster, enabling manufacturers to increase total production. From this perspective, the through hole assembly may take 1-2 hours to perform through the through-hole, SMT assembly only takes 10-15 minutes.
Simple:
In through hole assembly, the lead wire passes through the hole to connect the components. Since SMT components are directly welded to PCB, the overall composition is much simpler.
Less error-prone:
SMT assembly is very dependent on machines, not us humans. SMT can reduce the resistance and inductance of the connection, reduce the adverse effects of RF signals, and provide better high-frequency performance. It is almost completely automated.

What are the SMT IC package types?

There are many types of mounting processes for integrated circuit packages. Surface mount technology is just one of the more common and mature packaging types. The following are common package types in SMT assembly:

SOP: Small Outline Package;
SOJ: Small Outline J-Lead Package;
SON: Small Outline Non-leaded package;
QFP: Quad Flat Package;
QFJ: Quad Flat J-Lead Package;
QFN: Quad Flat Non-leaded package;
BGA: Ball grid array;
LGA: Land Grid Array;

SMT assembles the full manufacturing process.

SMT assembly process flow mainly includes the following steps: material preparation and testing, formwork preparation, solder paste printing, chip mounting, reflow, cleaning, inspection and repair, which will be described in detail below.

Material preparation and testing

Prepare SMT machine, SMT PCB, SMD components and check for any defects. PCB usually has flat, usually tin lead, silver or gold plated, non porous copper pads, called pads.

Formwork preparation

We can provide a fixed position for solder paste printing on the template, which is produced according to the design position of the bonding pad on the PCB.

Solder paste printing

Solder paste printing refers to the process of placing solder paste on the opening of PCB pad.
The template is used to provide a fixed position for solder paste printing. It is produced according to the design position of the pad on the PCB. Solder paste printing is realized by the solder paste printer placed in the first section of the SMT assembly line.

During this part, each pad must be covered with the correct amount of solder paste. Double sided smt assembly needs to ensure that the pads are covered with solder paste on both sides. Otherwise, when the solder melts in the reflow furnace, the connection cannot be established. It is very important to control the quality of solder paste printing process. This is because if no printing defects are detected at this stage, they will lead to further defects. For this reason, template design is the key, and the assembly team must be careful to ensure that the process is repeatable and stable. Fortunately, in order to make the process go smoothly, most solder paste printers can choose to include automatic inspection.
However, external machines are sometimes used to evaluate print quality. These solder printer inspection machines use 3D technology for more thorough inspection. This is because they check the amount of solder paste for each pad, not just the printing area.

Component placement

The purpose of mounting is to place the components in the corresponding positions on the PCB compatible with the design documents, and complete it on the mounting machine placed behind the SMT assembly line solder paste printer.

At this stage, each component to be mounted on the PCB will be removed from the package using a vacuum or gripper nozzle. After that, the machine places it in its programmed position. When all individual components are placed on the PCB, they must be checked to ensure that they are correctly placed. This is a very important step in the process, because if no placement error is detected and the part is welded to the position, it may lead to a lot of rework, which is expensive and time-consuming. Therefore, components need to be taken into account when drawing the PCB schematic diagram in the early stage. During PCB design, the placement of components should be reasonably placed according to the application of electronic equipment, impedance control and trace placement.

Reflow soldering

Once the placed components pass the inspection, the process will enter the reflow welding phase. In this part of SMT process, PCB is placed in the reflow welder. Many reflow soldering methods are used in SMT (Surface Mount Technology).

Here, all electrical welding connections are formed between components and PCBs. Using heat, earlier applied solder paste is converted to solder. Also, at this stage of the process, accuracy is critical because if the PCB is heated to an excessive temperature, parts or assemblies may be damaged, and the PCB will not work as expected. If the temperature is too low, the connection may not be established.
To avoid joint defects, the PCB must stay in each area for the correct time. They must also be completely cooled before handling or moving PCBs. If not, they may warp.

Cleaning

SMT solvent cleaning equipment/machine is used in electronic products to clean and remove excess flux and impurities after electronic PCB components are welded, and check defects.

Inspection

Use inspection during SMT assembly to ensure that the welding and assembly quality meet the corresponding manufacturing standards and regulations. X-ray and laser are the two most important automatic test equipment in the market. However, most electronics companies in the world rely on 2 to 10 times visual inspection, using microscopes or headlamps. A variety of equipment and tools can be used to participate in SMT testing, such as magnifying glass, microscope, ICT (online tester), flying probe testing, AOI (automatic optical testing), X-ray testing, function tester, etc. The detection equipment can be placed in any suitable position if necessary. Click to view the complete PCB inspection guide.

Rework

The purpose of rework is to repair or remanufacture the defective PCB. Usually, in this link, we need to use tools and equipment such as electric soldering iron and repair bench for rework. It can exist at any time in the SMT assembly line.

How SMT Helps the PCB Assembly Process?

The application of the SMT assembly process will bring the following benefits to the PCB circuit board:

Easy to assemble-
Since the component lead surface is mounted on the pad, there is no need to form a lead, which makes SMT assembly easier and faster. In through-hole technology, the opposite is true.
Reliability-
SMT is generally more reliable than through-hole components because it is not susceptible to vibration and shock. At the same time, the chance of component failure due to cold solder joints can be greatly reduced by using solder paste instead of molten solder.
Be able to use fine pitch elements-
In general, excellent spacers are allowed to be used in SMT assembly, which is never possible with through-hole technology. Its main advantage is that it can be used in small, high-density components.
Multi functionality-
SMT assembly technology is widely used in consumer electronics, telecommunications, medical equipment, industrial control systems and other industries.
Ability to use mixed technology PCB–
With the help of SMT assembly technology, PCB combining through hole and surface mount components is also possible. For example, it is very practical to use two or more types of applications at the same time when space is limited. The best example is in building a mixer board that contains fixed controls (through holes) and sliding faders.

What are the pain points of Surface Mount Technology?

Although SMT has several advantages, SMT technology also brings some disadvantages:

Unreliability-
If the components are subject to mechanical stress, it is not reliable to use surface mounting only as a method to connect PCBs. These components include connectors for smt assembly for connecting to external devices, which are periodically removed and reconnected.
Easily damaged-
Welding connections of SMDA may be damaged due to thermal cycling during operation. We cannot guarantee that the encapsulated compounds can be withstood by using welded links.
Limited space-
More skilled or expert operators and expensive tools can help you successfully perform component level maintenance and manual prototype smt assembly. Because of its small size and limited space, it may cause errors if you are not careful.
Inconvenient operation-
Most SMT component packages cannot be installed in sockets to facilitate the installation and replacement of faulty components.
Welding problems-
When we use SMT welding, we usually use less solder, so this may be the main reason why SMT welding is not reliable. Void formation may cause solder joint failure here. Generally speaking, solder is not resistant to high temperature, and it will fuse at high temperature. Therefore, we cannot use SMT technology to mass produce components that cannot withstand high temperatures. Solder will also be weakened by mechanical stress. This is equivalent to directly connecting the components that interact with users through the physical installation of through-hole.
Difficulty in maintenance-
SMDs are usually smaller than through hole components, leaving a smaller surface area for marking part IDs and component values. This makes it a challenge to identify components during prototyping and repair or rework.

As a professional smt assembly china factory, JHDPCB has the ability to solve all technical problems. Ensuring smooth and efficient SMT assembly.

What fields is SMT assembly used for?

At this time, most products are produced using surface mount technology. However, SMT is not applicable in all cases. Mainly used in:

Consumer electronics,
Telecommunications,
Medical equipment,
Industrial control systems,
Aerospace
National defense systems.

In general, SMT should be considered when:

You need to accommodate high-density components.
A compact or small product is required.
Although the density of components is high, your final product still needs to be fashionable and lightweight.
The requirements specify the high-speed/frequency function of the device.
You need to use automation technology for mass production.
Minimize the noise of the product (if any).

In a word, as a pcb smt assembly plant, JHDPCB can produce any SMT assembly, including broadcast smt assembly, camera smt assembly, financial electronics smt assembly, inverter smt assembly, led lighting smt assembly, massager smt assembly, mobile phone charger smt assembly, mobile power smt assembly, printer smt assembly, projector smt assembly, etc.

The development trend of SMT assembly.

Quick, Flexible and Fast-Responsive

Nowadays, the competition is becoming more and more fierce, and fast, flexible and fast corresponding technical equipment system has become a necessary skill for enterprises. In order to seize more opportunities and gain more profits in the market, we must first achieve this ability. Therefore, fast, flexible and fast response is the future development direction of SMT machinery.
As we all know, since the development of SMT assembly, from single equipment to multiple equipment, there is only one purpose – to improve mass production. People always pursue and aim at high efficiency, so it is also one of the ways to improve production efficiency and control efficiency. At the same time, in order to improve the production speed of SMT and reduce the floor space, many enterprises have developed from single line manufacturing to double line manufacturing.

Green and Environmental Protection

SMT board assembly line has caused great harm to the environment to a certain extent, whether in terms of packaging materials, solder paste, adhesives, fluxes and other application materials, or SMT assembly process. Nowadays, the more SMT PCB assembly lines, the higher the level, the more serious the damage to the environment. Therefore, the future surface mount pcb assembly line should advocate the adoption of green production lines.
Green manufacturing refers to the assembly and manufacturing of SMT when we meet the environmental requirements. We can carefully analyze the SMT assembly process and find out some possible pollution sources and pollution levels. After finding out according to this method, find out the equipment and materials that cause pollution during SMT production and manufacturing.

Finally, these equipment and materials shall be managed in a suitable, scientific and reasonable way to achieve two purposes of manufacturing and environmental protection. At the same time, we should also consider our own manufacturing scale and capacity. In addition, we should also select materials and equipment that have less impact on the environment and meet the environmental protection requirements from the aspects of design, SMT production line establishment, SMT equipment determination, material selection, etc.

Efficient Intelligence

The level of SMT printed circuit board assembly is reflected in the upgrading and development of smt assembly equipment. In the future, the important standard to measure the performance of SMT equipment is its manufacturing efficiency. In order to achieve this goal, we must improve the performance of the equipment.
The flexibility of SMT equipment is another development trend. With this capability, it can customize services according to the differentiated needs of users. At the same time, in order to improve the overall manufacturing efficiency, it can also meet different functions. It can be assembled with different precision and speed according to different component installation requirements.

SMT, which is the most new electronic assembly technology, has been used in many fields. It has completely replaced the traditional electronic assembly technology through its own properties and advantages. This has also brought substantial and revolutionary changes to the electronic industry. Therefore, in order to better serve other electronic industries, SMT assembly industry and its development trend are worthy of our attention.

Choose what JHD can do for you.

At JHDPCB, we work with you to follow your specifications. We can use any PCB assembly process according to your instructions. We also provide smt assembly service for different industries, including health care, consumer electronics, manufacturing, automotive and other industries.

Working with us ensures that you are involved throughout the process, making it cost-effective and ensuring that you get the products you need. JHDPCB provides quality assurance, has technical capabilities, and can reduce delivery time through automation. Because our SMT assembly technology has a SMT production line with 100000 components per hour. More sophisticated QFN and QFP packages can also be easily dealt with. Whether as a SMT PCB assembly supplier or as a PCB SMT assembly factory, we always provide the best pcb assembly service for every customer, and our smt assembly quotation will certainly satisfy you. We firmly believe that we can become the perfect partner for your next SMT assembly project.