Surface Mount Resistors

Small, with High Reliability

We offer a wide variety of surface mount resistors, also known as surface mount devices (SMD), including resistors suitable for pulse, surge, and voltage applications. Our standard thick film surface mount resistors offer power ratings of 6W and molded resistors to 7W. Our small SMD power resistors save space from traditional leaded products and offer a range of SMD thin film resistors with both NiCR and TaN film technology.

A surface mount resistor is a tiny rectangular ceramic body with silver conductive edges on either end. Also referred to as surface mount technology, an SMD resistor offers advantages in saving space on printed circuit boards (PCBs). It features the resistance value code printed onto it, where there is space. Solder paste is printed onto the mounting pads of a PCB, and the resistors are placed automatically onto these pads by pick and place equipment. The whole board is then passed through a reflow oven which melts the solder into place, making the contacts.

 

A surface mount resistor provides the same functionality as the more traditional axially leaded resistors but has a lower power dissipation capacity and oftentimes a lower stray inductance and capacity. Surface mount resistors can be thick film, which is most commonly used, thin film, which offers accuracy and stability, metal strip, for current sensing, or wirewound, which is molded construction as opposed to a flat chip.

 

Surface mount resistors are used in large quantities and are the preferred resistor for use in electronics equipment, because of the small size and high reliability. Surface mount resistors are commonly used in telecommunication, automotive, and medical equipment, as well as in personal devices, displays, and advanced technology research instruments.

Frequently Asked Questions

FAQs about Surface Mount Resistors

Q: What are SMD resistors?

A: SMD stands for Surface Mount Device. An SMD is any electronic component that is made to use with Surface Mount Technology (SMT). SMT was developed to meet the ongoing demand for printed circuit board (PCB) manufacturers to use smaller components that are faster, more efficient, and cheaper. SMDs are smaller than through-hole resistors and instead of having wire leads that go through PCB, they have terminations that are soldered to pads on the surface of the board. This eliminates the need for holes in the board and allows both sides of the board to be used more fully.

 

Q: How are SMDs made?

A: SMDs are made by placing end connection electrode bases onto an alumina or ceramic substrate. The resistor is then fired to ensure the electrodes are held in place. Next, a film of resistive material is printed or deposited and the resistor is fired again. The resistor is then covered with successive layers of a protective coat that dry between applications. These layers prevent mechanical damage and ingress of moisture and other contaminants. Finally, a marking is placed on the resistor if the surface is large enough. The resistors are packaged in a form of blister roll for use on pick and place machines, or they can be supplied as loose components.

 

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