SMD/SMT and THT are two major assembly methods used in electronics manufacturing. They are not simply a modern-versus-old choice. The right method depends on package availability, board size, mechanical requirements and the intended manufacturing flow.
SMD/SMT assembly
Surface-mount components are soldered to pads on the PCB surface. Compact packages and automated placement make SMT suitable for high-density boards and modern electronic products.
THT assembly
Through-hole components use leads that pass through holes in the board before soldering. Terminal blocks, connectors, relays, transformers and other mechanically significant parts may use this structure.
Main differences
SMD generally supports higher board density and automated production. THT may provide useful mechanical anchoring for selected parts. Component availability also influences the method because some ICs are surface-mount only while many larger electromechanical parts remain through-hole.
Mixed assembly
A control board may use SMD ICs and passive components together with THT relays or terminal blocks. Accurate package information in the BOM becomes especially important in a mixed assembly.
How to choose
Consider physical size, component packages, mechanical loads, production volume, electrical and thermal requirements, and service needs. If the design is already complete, technical evaluation should be based on the actual BOM and PCB data.
When requesting PCB assembly from SEMKO, indicate SMD/SMT, THT or mixed assembly and include the relevant manufacturing files. Component requirements can be submitted within the same component supply scope.
Frequently Asked Questions
Is SMD assembly better than THT?+
Neither is universally better. The decision depends on board size, component type, mechanical requirements and production planning.
What is mixed assembly?+
It is a PCB assembly that uses both SMD and through-hole components.
Is THT used only on old electronics?+
No. Modern products may still use THT connectors, relays, terminals and other parts.
Can SMD and THT parts be listed in the same BOM?+
Yes. Accurate part numbers and package information are important for both sourcing and assembly.
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