SMD assembly

An introduction of SMD assembly

SMD: It is the abbreviation of Surface Mounted Devices, which means: Surface Mounted Devices, which is one of the SMT (Surface Mount Technology) components. In the initial stage of electronic circuit board production, through hole assembly is completely done manually. When the first automated machines came out, they could place some simple lead components, but complex components still required manual placement for reflow soldering. Surface Mounted components mainly include rectangular chip components, cylindrical chip components, composite chip components, and special-shaped chip components.

Features of SMD:

High assembly density, small size and light weight of electronic products. The volume and weight of SMD components are only about 1/10 of those of traditional plug-in components. Generally, after SMT is used, the volume of electronic products is reduced by 40%~60%, and the weight is reduced by 60%~ 80%.

High reliability and strong anti-vibration capability. Solder joint defect rate is low.

Good high frequency characteristics. Electromagnetic and radio frequency interference is reduced.

Easy to automate and improve production efficiency. Reduce costs by 30% to 50%. Save material, energy, equipment, manpower, time, etc.

The processing workshop can do the following visual inspections:

1. Visually or use a magnifying glass to check whether the soldering end or the surface of the lead of the component is oxidized or whether there is any contamination.

2. The nominal value, specification, model, precision, and external dimensions of the components should be consistent with the product process requirements.

3. The pins of SOT and SOIC cannot be deformed. For multi-lead QFP devices with a lead spacing of less than 0.65mm, the coplanarity of the pins should be less than 0.1mm (it can be optically detected by the placement machine).

4. For products that require cleaning, the markings of components will not fall off after cleaning, and will not affect the performance and reliability of components (visual inspection after cleaning).

Surface Mount Notes:

a. Micro SMD surface mount operations include:

1. Printing flux on PCB;
2. Use standard pick and place tools for component placement;
3. Reflow and cleaning of solder (depending on the type of flux).

b. Surface mount advantages of micro SMD include:

1. Shipped in standard tape and reel packaging for easy handling (in compliance with EIA-481-1 specifications);
2. Standard SMT pick and place tools can be used;
3. Standard reflow soldering process.