What is SMD / SMA / SMT / SMC / SMP / SME? What’s the difference?

Picture Description : Surface Mount Device ( SMD ) Example 7-segment display with Surface Mount Package ( SMP )

What is SMD?

SMD is the initial for Surface Mount Device. The main components for SMT ( Surface Mount Technology ) process. It’s common industry statement to mention about SMP ( Surface Mount Package ) , SMA ( Surface Mount Assembly ), SMC ( Surface Mount Components ), SME ( Surface Mount Equipment ).

To clarify what’s SMD / SMA / SMT / SMC / SMP / SME

▲ The explanation for the SMT releated abbreviation made by OPTO PLUS LED Corp.
▲ The explanation for the SMT releated abbreviation made by OPTO PLUS LED Corp.

SMT ( Surface Mount Technology )

The SMT stand for the ” Surface Mount Technology “. This technology is the mostly used mess production technology for modern electronic product to automatic assemble large amount of electronic component to PCB ( Printed Circuit Board ) .

SME ( Surface Mount Equipment )

​The equipment for Surface Mount Technology is called Surface Mount Equipment. This is the equipment to do the Surface Mount Components to PCB. The major equivalents include:

▲OPTO Plus SMT Line, the nearest machine to the farthest machine: Solder printing machine /Pick & Place machine / Reflow Oven / offline AOI​ machine

SMP ( Surface Mount Package )

The device need a special package for Surface Mount Equipment to assembly SMC ( Surface Mount Components ) to PCB ( Printed Circuit Board ) is call SMP ( Surface Mount Package ).

SMC ( Surface Mount Components )

The component package for Surface Mount Technology to assembly to PCB ( Printed Circuit Board ) is call SMC ( Surface Mount Components ) . Two kind of SMC ( Surface Mount Components ) were call when the Surface Mount Components Package different electronic component inside.

SMD (Surface Mount Device)

Each electronic component can be package as SMC ( Surface Mount Components ) , different name were call depend on it’s complexity. Generally, only one electronic component was package for Surface Mount Technology is called SMD ( Surface Mount Device ) , for example, 0402 package capacitor , 0603 package LED.

smd size chart
▲ The common electrical components SMP & dimension.(REF: Wikipedia)
VISIBLE LED - PCB/Top View
a branch of 0603 SMD package VISIBLE LED – PCB/Top View

SMA ( Surface Mount Assembly )

On the other hand, More then one electronic component were package is called SMA ( Surface Mount Assembly ) . Modules that includes multiple active or passive electronic component. For example, seven segment display,( multiple LED assembly as a module) blue tooth modules, and WIFI module.

7-segment display
▲SMA ( Surface Mount Assembly ) Example – 7 segment display

Venn diagram for SMD / SMA / SMT / SMC / SMP / SME

We try to use Venn diagram to show the relationship for this term. some of these term were misuse in many daily conversion and article. For example, call SMA as SMD or even SMC. Hope this diagram clarify these professional term.

Simple SMT Assembly process breakdown

A product use SMT ( Surface Mount Technology ) to assembly electronic component to PCB may have different name. Such as, SMT Line Stand for Surface Mount Technology Product Line. SMTA Line stand for Surface Mount Technology Assembly Line. Or even call SMA, Surface Mount Technology Assembly. You have to check SMA meaning from the paragraph. but all abbreviation mention above means a product line that use SMT ( Surface Mount Technology ) to assembly electronic component to PCB, Which have 3 main process:

  • Solder paste printing process
    • Use SME: Automatic solder paste screen printer
  • Pick-and-place process
    • Use SME: Pick-and-place machine / Mounter machine
  • Reflow soldering process
    • Use SME: Re-flow oven

Below is the simple diagram for SMT process, for example, we are going to SMT a 0603 packaged resistor. Firstly, we need to clean the PCB, and then use the solder paste screen printer to print the solder on the solder pad. At this moment, the solder is in cream type. Then, use the pick & place machine to assemble the resistors onto the solder paste. As the solder paste is still in cream type, the resistors will be sink and fix into the solder paste. The use re-flow oven process, due to heat the solder past can combine the resistor and PCB together.  In case, there are no outside tension or high heat, the resistor & PCB won’t be separate. Then, the SMT process is completed.

This is the simple diagram for SMT process, for example, we are going to SMT a 0603 packaged resistor.
Simple SMT Assembly Flow made by OPTO PLUS LED

Conclusion

This article is just to introduce the related technology for SMD & SMT, and do hope it can help readers to verify the difference in between simply. Opto Plus LED Corp. is the professional manufacture for SMD LED display (from simple 7-segment to complicate custom LED display with IC driver).  If you have any inquiry or questions related to LED display, please send your questions via [email protected]

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