The Advantages and Disadvantages of SMT assembly

SMT assembly

SMT is the surface paste or surface installation technology. It is a circuit that will install non -pitch or short -drawn surface assembly components (referred to as SMC/SMD) on the surface or other substrates of the printed circuit board. Installation technology.
Under normal circumstances, the electronic products we use are designed by PCB plus various capacitors, resistors and other electronic components according to the design of the circuit diagram. Therefore, various electrical appliances need a variety of different SMT patch processing processes to process.


SMT Assembly process

SMT basic process constituent elements include: silk marks (or point replenishment), stickers (curing), return welding, cleaning, detection, repairs.

1. Silk printing: Its function is to print the welded paste or patch glue to the pad of PCB to prepare for the welding of the component. The device used is a wire printer (wire printing printer), located at the forefront of the SMT production line.

2. Plugs: It is to drop glue to the fixed position of the PCB board. Its main function is to fix the component to the PCB board. The device used is the point -end or behind the detection device of the SMT production line.

3. Paste: The role is to accurately install the surface assembly device to the fixed position of the PCB. The device used is a patch machine, behind the silk printer in the SMT production line.

4. CICS: Its role is to melt the patch glue, so that the surface assembly component is firmly glued with the PCB board. The device used is a solid furnace, behind the patch machine in the SMT production line.

5. Back welding: Its role is to melt the welding paste so that the surface assembly component is firmly glued with the PCB board. The equipment used is a reflux furnace, which is behind the patch machine in the SMT production line.

6. Cleaning: Its role is to remove the harmful welding residues on the human body on the assembled PCB board. The equipment used is the cleaning machine, the position can be not fixed, it can be online, or it is not online.

7. Detection: Its function is to detect the assembled PCB board and detect the quality of welding and assembly quality. The devices used include magnifying glass, microscope, online tester (ICT), flying needle tester, automatic optical detection (AOI), X-Ray detection system, function tester, etc. According to the needs of the test, the location can be configured in a place where the production line is appropriate.

8. Rebate: Its role is to rework the PCB board that detects faults. The tools used are soldering iron, returning workstations, etc., which can be configured in any position in the production line.


Advantages of SMT assembly

SMT has many advantages over conventional through-hole technology:

◆Surface mount technology supports microelectronics by allowing more components to be placed closer together on theboard.This leads to designs that are more lightweight and compact.

◆The process for SMT production setup is faster when compared to through-hole technology. This is because components aremounted using solder paste instead of drilled holes. lt saves time and labor-intensive work.

◆Components can be placed on both sides ofthe circuit board along with a higher component density with more connections possible per component.

◆Due to the compact size ofthe package, higher-density traces can be accommodated on the same layer.

◆The surface tension of molten solder puls components into alignment with solder pads, which automatically corrects minorplacement problems.

◆Compared to through holes, these do not expand in size during the operation. Hence you can reduce the inter-packagingspace.

◆Electromaanetic compatibility is easilv achievable in SMl boards because ot thelr compact package and lower lead inductance.

◆SMT enables lower resistance and inductance at the connection, t mitigates the undesired efects of RF sianals and providesbetter high-frequency performance.

◆More parts can fit on the board easily due to their compactness, resulting in shorter signal paths. This enhances signal integrity

◆The heat dissipated is also lesser than through-hole components.

◆SMT reduces board and material handling costs.

◆Enables you to have a controlled manufacturing process. This especially opted for high-volume PcB production.

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SMT assembly
Disadvantages of SMT assembly

Even though SMT has several advantages, the technology also comes with it certain disadvantages:

◆When you subject components to mechanical stress, it is not reliable to use surface mounting as the sole method ofattachment to the PcB, This is because vou need to use component connectors to interface with external devices that areperiodicallyremoved and re-attached,

◆Solder connections for SMDs might be damaged through thermal cycles during operations.

◆You would need highly skiled or expert-level operators and expensive tools for component-level repar and manual prototypeassembly, This is because ofthe smaller sizes and lead spaces.

◆Most SMT component packages can’t be installed in sockets that enable easy installation and replacement of failedcomponents.

◆You use less solder for solder joints in SMT, therefore the reliability of solder joints becomes a concern, void formation mightlead to solder joint failures here.

◆SMDs are typically smaller than through-hole components leaving lesser surface area for marking part IDs and componentvalues. This makes identifying components a challenge during prototyping and repairing the PCB.

◆The solder can melt when exposed to intense heat. Therefore, SMT cannot be implemented in electrical load circuits with highheat dissipation.

◆PCBs that use this technology requires more installation costs, This is because most ofthe SMT equipment such as the hot ailrework station, pick and place machine, solder paste screen printer, and reflow oven are expensive.

◆Miniaturization and a variety of solder joints can make the procedure and inspection more difficult.

◆Due to compact size, there is an increased chance of solder overflow that can result in short circuits and solder bridge.


When  use SMT installation and stickers?

The application scenarios of SMT are very wide, mainly in the following cases::

1. Electronic product miniaturization and high performance requirements: When the design of electronic products needs to be miniaturized and compact, and has high requirements for performance, SMT installation and paste technology is a key means to achieve this goal. Due to the miniaturization of SMT patch components, it can achieve more functional modules in limited space content, thereby achieving smaller and lighter electronic products.

2. Improve product reliability and stability: SMT installation and paste technology can improve the reliability and stability of electronic products, reduce the problem of poor contact or looseness that may bring pitch connection. Especially in the fields of automotive, medical equipment, military, etc., the stability and reliability of the product are extremely high. SMT installation and paste technology can ensure the accurate paste of electronic components and meet these requirements.

3. Reduce production costs and improve production efficiency: SMT installation and paste technology can achieve high density assembly of circuit boards, thereby improving production efficiency. In addition, due to its high degree of automation, it can greatly reduce the needs of manual operation and reduce production costs.

4. Copy the assembly requirements of complex circuit boards: For electronic products with complex circuit design, SMT installation and paste technology can achieve precise paste of tiny meta -device to ensure the high performance and compact design of the equipment.

The application of SMT installation technology in the electronic manufacturing industry has become more and more extensive, becoming one of the mainstream technologies for electronic products. With the continuous development and popularization of electronic products, SMT installation and posting technology will continue to play its important role and promote the progress of the electronics industry.


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