Surface Mount Technology (SMT) terminology
- Surface mount components/surface mount device. Component usually
refers to passive items such as resistors, capacitors, ect. Device
refers to active items such as SOIC, PLCC, ect.
- Metalized electrode face (or most end up lying on floor). Cylindrical
and usually color-coded resistors or solid-colored diodes.
- Small outlined integrated circuit. This smaller version of the DIP
has leads that are gull-wing shaped to allow connection to the
- Plasitc leaded chip carrier. Normally a four-sided quad package in
which an IC is installed with J-type leads extending out from the
sides of the package then downand rolled under the body of the
- Small outline J leaded package similar to a DIP but for surface mount
- Small outline, 16 J leads.
- The metal pads on the substrate intended for mounting specific
- Small outline transistor/small outline diode. A plastic leaded
component in which diodes and transistors are packaged. Gull-wing
leads are used.
- Thermal coefficient of expansion (coefficient of thermal expasnsion).
The rate of expansion or contraction of a material when its
temperature is increased or decreased.
- Each lead of a multileaded item being at the same level or plane.
This is extremely important to ensure that all lead are properly
- Leadless ceramic chip carrier. A ceramic package with an IC mounted
to form a surface mount device. Its termination areas for soldering
are built into the ceramic material and do not allow for TCE of the
device versus the substrate, especially if the component and board
materials are different.
- Quad Flat pack. Four-sided device normally with extended
- Thin shrink small outline package. Similiar to SOIC but smaller
packaging and closer lead spacing (8 to 24 leads) with leads
protruding from the ends of the package.
- Type I Assembly
- Circuit board with SMC/SMDs on one or both sides.
- Type II Assembly
- Circuit board with a combination of THM on the top of the board and
SMC/SMDs on the top and bottom of the board.
- Type III Assembly
- Circuit board with THM on the top of the board and passive surface
mount on the bottom.
- Solder paste/cream
- Semiliquid substance made up of tiny solder balls, flux, solvent and
an an antislumping agent.
- Reflow soldering
- The reflowing of the solder paste.cream used to solder SMC/SMDs onto
the board surface. The solder paste/cream is heated until it melts
and flows, usually using an infared, convection or vapor phase
- The damage to a circuit board caused by ovberheating. Usually shows
as small white dots on fiberglass epoxy boards around the overheated
area. This is the weave of the fiberglass seperating inside the
- Blind via
- Surface mount connection hole where the board is multilayered and the
hole is attached to the surface (top or bottom) and only goes partway
through the board.
- Buried via
- Similar to a blind via, except that it connects internal layers only
and is not exposed to top or bottom suraces.
- Ball grid array
- A large IC carrier with small solder protrusions on the bottom of the
package for attaching to the appropriate pads on the circuit board.
Difficult if not impossible to remove/install without the proper