What is the Difference Between SMT and SMD?
SMT refers to a specific type of assembly technology and is commonly associated with terms like assembly, soldering, and process. On the other hand, SMD represents a type of electronic component and is typically used in conjunction with words such as component, part, etc.
The electronics manufacturing industry operates with a set of professional abbreviations, often using terms like PCB (printed circuit board), PCBA (PCB assembly), Through Hole Technology (THT), and more. While these abbreviations are second nature to industry insiders, they might be less user-friendly for novices or electronics enthusiasts. In this article, FS Technology aims to demystify two commonly used terms in the PCBA industry—SMT and SMD—by exploring their concepts, applications, and how they interconnect.
What is SMT?
Basic Concept Explanation
SMT, or surface mount technology, represents a modern approach to arranging components on a printed circuit board (PCB). Widely adopted in the PCBA industry, nearly all companies offering PCB assembly services include SMT assembly in their repertoire. In the early 1970s, electronic manufacturers relied on through-hole assembly for component mounting and soldering, where component leads were inserted into drilled holes on bare PCBs, and permanent arrangements were achieved through soldering guns. However, as technology advanced, through-hole PCB assembly proved to be less optimal, prompting the emergence of SMT assembly as a viable alternative.
Diverging from traditional plug-ins, SMT technology employs leadless assembly to directly solder components onto the bare PCB. This method is faster and more cost-effective. Given the rapid pace of updates for consumer electronic devices such as mobile phones and computers, manufacturers require automated PCB assembly to meet the demands of large-scale production, a need effectively addressed by SMT technology.
Features of SMT
Reduce parasitic capacitance and parasitic inductance;
Reduce the demand for components in PCBA projects;
Automated new equipment enables fast and reliable large-scale production;
Facilitating the development of tiny electronics or implantable devices.
What is SMD?
Basic Concept Explanation
To grasp the fundamental workings of a PCB, it's crucial to understand its two main elements: the bare board and the components. The bare board serves as a foundational platform for mounting components and creating electrical pathways. As current flows through the circuitry, it reaches the components, enabling their operational functions. Hence, the components play an active role in defining the capabilities of the PCBA board. SMD represents a specific category of these components.
SMD, or Surface Mount Device, denotes an electronic component designed to be soldered directly onto a printed circuit board. Currently, various installation methods exist for PCB components, categorizing them into types such as DIP components and SMD components—referring to plug-in and patch components, respectively. Influenced by the trend toward miniaturization, the production of PCBA increasingly favors the utilization of SMDs.
Features of Surface Mount Device
The SMD body is on the same side as the solder joints;
SMD has no leads or only short leads;
Smaller size but better performance;
Reduce the risk of PCBA manufacturing errors by reducing through holes.
SMD vs SMT
The difference between SMD and SMT is that SMD (surface mount device) refers to an electronic component mounted on a PCB.
In contrast, SMT (surface mount technology) relates to the method used to place electronic components on a printed circuit board.
Difference
Conceptual Difference: SMT refers to a specific type of assembly technology and is commonly associated with terms like assembly, soldering, and process. On the other hand, SMD represents a type of electronic component and is typically used in conjunction with words such as component, part, etc.
Usage Difference: The SMT process is tailored exclusively for SMD components and is not compatible with through-hole components. On the other hand, SMD components can be applied to circuit boards using various soldering processes, contingent on their properties and characteristics. These processes encompass manual soldering, hot air melting, hot plate heating, and wave soldering, among others.
Purpose Difference: The primary objective of the SMT process is to attain automation and precise installation, thereby facilitating efficient production. In contrast, the incorporation of SMD electronic components primarily aims to achieve miniaturization and high-density integration within electronic systems.
Combination
While SMD and SMT are distinct concepts, they synergize in the field of electronics manufacturing. Examining the historical evolution of PCBA reveals a decline in DIP components, partly due to the limitations of manual soldering, leading to the introduction of pick-and-place machines. The use of manual soldering for traditional SMD component assembly has been superseded by placement machines. In the contemporary era, simplicity, efficiency, and cost-effectiveness are pivotal for progress, and the integration of SMT and SMD adeptly meets these criteria.
The automated production mode aims to optimize the cost of PCB assembly, with SMD providing a cost-effective solution in this context. SMT equipment facilitates the swift installation of thousands of SMD components on the board within a short timeframe. The compact size of SMD components contributes to increased circuit board capacity, a benefit effectively harnessed by SMT technology. Furthermore, SMD components employ lead-free soldering, enabling PCBA companies to reduce assembly failures and enhance the overall reliability of the SMT process.
