How To Install SMD Components? SMD Assembly China 2022

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The electronic industry is developing at a rapid pace, and now the main advantages of the devices are: compactness and miniaturization, ease and speed of installation, reliability and high functionality. These features can only be obtained by mounting smd components in an automatic way. 

The demand for the technique is explained by the joint benefit for manufacturers and customers - a combination of the speed of production processes and the lower cost of the finished product. 

Our company performs installation of smd components, which allows you to reduce the cost of components by 20-30%, in contrast to the through-hole service, and precision installers give you the advantage of fulfilling orders in large volumes.

kingford pcb


Mounting smd components is a method when the elements are attached directly to the metallized tracks that are on the dielectric plate. With this method of soldering, it is not necessary to form holes, so the working space is used more rationally.

 Because of this, the parameters and weight of the product are reduced, and the speed of receiving signals only increases. It is for this reason that the installation of smd components is at the peak of popularity.


  • A special paste with solder is applied to the contact points using stencils.
  • The installation of smd components is carried out with the help of a professional installer.
  • Components are group soldered in convection ovens.
  • Testing and visual control of the finished product for compliance with technical parameters is carried out.
  • Varnishing and packaging of finished products, if required by the customer.

Ease of production processes

Mounting smd components greatly simplifies production processes. There are no complex preparatory and installation works, no need to prepare conclusions and make holes. Soldering does not leave bumps on the surface, which must be disposed of. The technology of mounting smd components does not require a lot of manual labor and reduces everything to automation, which avoids labor intensity and huge staff costs.

Electronic products are lighter and more compact for several reasons:

  • There are no holes on the PCB.
  • Installation of smd components is carried out with small elements.
  • Components are fixed on both sides of the panel.
  • Some components can be installed in the inner layers of the plate.
  • The small dimensions of the elements increase the density of the product in a small area.

The reduction in size and weight significantly reduces the size of electronic products. This increases the functionality of the product, and also reduces the cost, because the components are lighter and less required.


  • The technical qualities of the product increase - the density of the arrangement of parts not only reduces the microcircuits, but also increases the technical characteristics of the product. 
  • Mounting smd components reduces the length of the pins and improves the speed of data exchange between the elements. Moreover, both weak and high-frequency electrical signals are accelerated.
  • Ease of repair and maintenance. Installation of smd components simplifies and reduces the cost of repair work. With surface mounting, the elements are installed in such a way that, with the help of modern equipment, they can be easily removed, corrected and returned to their place. 
  • No need to clean and warm the solder, as in the output wiring - you just need to act on the area with hot air. You can't do this with through-hole wiring because the components are tightly fixed in the holes.
  • Automation speeds up the production process several times and minimizes possible defects due to the human factor. When smd components are mounted, boards are multiplied - they are placed on the same workpiece with connecting jumpers.
  •  This saves time for the delivery and unloading of boards to an automated device, after which it assembles all the boards at once using a multiplied blank. This technique saves time, especially with small-sized nodes.

SMD PCB assembly

Physical and electrical fastening of electronic components to the board is carried out by surface and through methods or by a combination. The first one is SMD-mounting.

SMD mounting is a method of soldering elements in which the output contacts do not pass through the base of the dielectric. Electrically conductive tracks for surface mounting can be applied on one or two sides of the board or on the inner layers if the printed circuit board is multilayer.

PCB assembly

SMD-mounting is performed using special high-precision equipment. It is carried out in several stages:

  • printed circuit board production;
  • application with a syringe dispenser or a screen printer (if stencils are available) of solder paste;
  • installation of surface electronic components on the surface of the printed circuit board;
  • board soldering in an oven (solder paste reflow);
  • washing, drying the finished product (if necessary);
  • Application of protective coatings (for example, protective varnish).

Heating of circuit boards in a solder paste reflow oven is most often carried out by convection. If the production is small-scale or soldering of individual SMD elements is required, it is performed manually.

 For this, soldering guns are used. The soldering temperature is selected individually, with a focus on the technical parameters of all components, their maximum thermal load.

Surface Mount Features

SMD soldering of elements may have specific requirements for the dielectric base and paste. Output mounting involves the passage of the contacts of the elements through, while surface mounting is fastening directly to the surface of the printed circuit board.

Particular attention should be paid to the choice of solder paste. Its composition is a heterogeneous mixture of powdered solder, fluxes, and sometimes stabilizing fillers. Solder paste is designed to perform a number of important functions:

  • cleaning the treated surface from oxides (removing the oxide film);
  • increasing the wettability of solder contact pads;
  • solder spreading, which becomes liquid when heated;
  • creating a contact between the elements and the board;
  • fixing the components on the plate.

Solder paste plays the role of flux and solder at the same time. When soldering SMD parts, the flux cleans the work surface, the solder provides full electrical contact between the elements and metallized tracks. The paste is heated under the influence of high temperature. 

This ensures the spreading of the solder and the high-quality connection of the elements with the electrically conductive circuit.

Surface Mount PCBs: Advantages and Disadvantages

Soldering electronic components in the SMD way confidently displaces TNT (DIP). Today, more and more elements are surface-mounted instead of output-mounted. This is due to a number of important advantages of SMD installation over output:

  • minimum dimensions of contacts;
  • no need to trim the leads after soldering;
  • smaller size and weight of elements;
  • no need to drill holes in the board;
  • ease of installation;
  • use of boards on a metal basis is available.

Surface mounting of electronic components is easier to automate. This is due to the separation in time of individual technological processes. When soldering SMD components, solder paste is first applied, then chip elements are installed, and then the finished product is subjected to group soldering.

 Each of these stages proceeds with the use of special semi-automatic and automatic equipment, which eliminates the need to perform many operations exclusively manually.

The above advantages determine the presence of the following advantages of surface mounting:

  • increased density of components due to their small size, contact leads, working surface;
  • reduction in weight and dimensions of the finished board;
  • Reduction in the cost of manufactured printed circuit boards.

Surface mounting is deservedly more popular than output. Soldering SMD components is an alternative to the traditional soldering of contacts with a soldering iron. And yet, along with the advantages, it has disadvantages over TNT editing:

  • the need for more functional and expensive equipment;
  • the need for special tools and highly qualified engineers for manual installation;
  • the materials used must be of exceptionally high quality and stored under conditions with increased requirements for protection from external influences;
  • group soldering requires precise observance of the temperature and heating time of the microcircuit.

Topological design of boards obliges to take into account as much as possible the electrothermal characteristics of both the printed circuit board itself and the mounted elements. After fixing the components, a minimum gap remains between them and the base.

This can cause local overheating of individual sections of the assembled printed circuit board. To prevent such a problem, it is important to accurately consider the thermal expansion coefficients, the allowable stress ranges of each element, and other parameters.

Soldering SMD resistors

Resistors as resistance elements are included in almost all printed circuit boards, regardless of the specifics of the devices in which they are packaged. At present, when more than 90% of microcircuits and components are produced for mounting by the SMD method, mainly surface elements are used, as a result of which the soldering of SMD resistors becomes relevant.

The process of soldering surface resistors

Mounting of SMD-type passive resistance elements is carried out in the general flow of fixing surface chips. Operations are performed on semi-automatic and automatic equipment under the control of operating engineers. The soldering process consists of several successive stages:

  • study of technical specifications for the created fee;
  • cutting blanks of dielectric plates;
  • creating a metallized pattern on the surfaces of future boards, drilling holes for DIP mounting (if necessary);
  • applying a protective coating;
  • creating stencils for applying solder paste;
  • preparation of production, selection of necessary elements;
  • applying and distributing solder paste over contact pads on a screen printer;
  • installation of surface components (including resistors);
  • heat treatment of boards in a soldering furnace;
  • washing and drying of printed circuit boards;
  • installation of output elements (if necessary);
  • checking the performance of finished products.

The application of solder paste is carried out on special machines with dispensers. Stencils made of stainless steel sheet are fixed on the plates. Their holes precisely match the position and thickness of each solder point. Solder paste is applied to all contact pads provided by the stencil. In accordance with the computer algorithm, the machine installs all SMD components, including resistors.

After that, the board is sent to the group soldering oven. By convection heating, the solder paste is heated. The flux included in its composition cleans the contact surface, and the solder ensures the connection of the chip leads to the electrically conductive circuit. 

When the soldering process is completed, the product is cleaned of flux residues, solder and its Quality Control Department is checked. If the board fully complies with the requirements of the specification, it is packed for shipment to the customer.

How much does it cost to solder SMD COMPONENTS?

The price of mounting printed circuit boards - both surface and output - is individual for each project. You can find out the cost after reaching to us. Generally, engineers determine:

  • complexity, purpose of boards;
  • the number and type of components used;
  • a set of necessary production operations and other information.

Based on this, an accurate calculation of the cost of manufacturing and mounting boards is carried out. Many parameters affect the production price, including complexity, board layering, standard sizes of the elements used.

The cost of soldering SMD resistors is indicated in the overall estimate and reported to the customer initially. If approved, a bilateral contract for the provision of services is signed and the production process is launched.

Soldering resistors on the board: Conclusion

In order for an electronic product to work properly, it is necessary to select the optimal technological process, and then solder each of them to the board. The solution of this problem should be entrusted to experienced craftsmen. Kingford employs a staff of highly qualified specialists. Armed with modern automatic equipment and hand tools, our employees carry out the installation of boards of any complexity and purpose.


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