Advanced Circuits, Inc. (ACI)

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What Surface Mount Technology Is And Why to Embrace It

When a person takes a look at a commercially-made electronic item in the modern world, the inside is often going to be composed of many tiny devices. Instead of using conventional parts with wire leads as might be seen for home projects, the components are often mounted onto the surface of boards. In many cases, these boards are truly minuscule.

This is a type of technology called surface mount technology or SMT. Almost all of the equipment manufactured commercially today uses this innovative technology. Surface mount technology has huge advantages when manufacturing printed circuit boards (PCBs). Because the components on SMT boards are so small, it also lets people pack more electronics into a small space.

What Surface Mount Technology is All About

The 1970s and 80s were a time when automation started to take off for printed circuit boards used in all sorts of equipment. Traditional components using leads weren’t easy to use with PCB assembly. For capacitors and resistors, the leads had to be pre-formed to fit through holds and integrated circuits had to have leads set at a specific pitch to go through holes quickly and easily.

This led to difficulty since many of the leads would miss the holes because the holes were quite tight. Because of that, an operator would need to step in and resolve the problems to make the components fit. This meant a loss of time and money since the machines automating the process had to be stopped.

Printed circuit boards remove the need for leads to go through the board. Instead, components could be soldered right to the board. This led to the birth of SMT and the use of components for SMT has risen quickly because of its many advantages. Nowadays, surface mount technology is the primary option for assembling PCBs in electronics manufacturing. The products made can be small and used in many different ways.

Why Surface Mount Technology is Favored in Design

While the primary reason for moving to surface mount technology was related to cost, speed, and reliability, there are other benefits. This technology has had a huge impact on the way that people today design and develop new circuits and equipment. The good thing about this is that the change has largely created advantages rather than disadvantages. Some things to be aware of for developers using surface mount technology are listed below.

  • Circuits Are Smaller and Denser Than Ever – The electronics industry has always had the drive to offer more function in smaller packages, but that was never an easy task before surface mount technology became widespread. SMT is designed to make this simple since everything is in a miniature format. Components can be extremely small and mounted closer together on the circuit board than would ever be possible with typical components with leads. This, combined with the better functionality available through integrated circuits, makes life easier for a development engineer.
  • Lower Power Rating Requirements – One of the most important things to look for when designing and producing electronics is the power rating of the components. With surface mount technology, devices can have lower power ratings than ever before. As an example, a standard resistor with a lead can dissipate 0.25 watts or even more. However, surface mount resistors are smaller so the dissipation is also lower. People should be aware of this during a build but always make sure to check the manufacturer’s data for the exact numbers.
  • Less Inductance and Spurious Capacitance – Since surface mount technology components are smaller, that also means that spurious inductance and capacitance are also going to be smaller. An SMT resistor, to keep with the previous example, will be closer to an ideal resistor than a resistor with leads. In the same way, a surface mount technology capacitor is going to create less parasitic inductance. When taking this all together, standard SMT components will have higher frequencies and faster speeds than leaded components are capable of.

Using Surface Mount Technology with Printed Circuit Board Assembly

Nowadays, SMT is used in almost all facets of PCB manufacturing and assembly. More electronics can be placed in a smaller space using the technology. All of the components are smaller and many of them offer better performance than traditional components. They also can be easily used with automated machines to eliminate the need for worker intervention during the assembly process.

With wired components, it was always a challenge to rely on automatic placement. All wires had to be pre-made to fit the correct hole spacing and, in some cases, there were still issues with placement. PCB assembly typically has all components placed automatically. Manual assistance might be occasionally needed but it is rare. High-quality circuit boards reduce the need for this to the point of even changing a design so components fit perfectly.

One issue that used to be common with surface board technology components was their lack of resistance to heat. Since the components are soldered in, this raises the temperature of the part and could cause issues in some situations. However, new components have been developed that have no problem tolerating the temperatures associated with the soldering process.

SMT Components and Devices

Surface mount components differ from leaded components since they are set into a board and soldered to it rather than wiring between two points. The leads don’t go through holes as might be expected of traditional components. There are three package styles used for SMT components: transistors and diodes, integrated circuits, and passive components. Many passive components consist of resistors and capacitors in standard sizes with typical package sizes. Transistors and diodes often come in a small plastic package, while there are many package options for integrated circuits.

Any business creating a project using printed circuit boards should consider the ease and convenience of surface mount technology. At Advanced Circuits, we offer printed circuit boards that are high-quality and ready for this kind of technology. We also provide assembly and manufacturing services to save people time and money. Regardless of the size of a business or how large their circuit board order is, we’d love to help. Get in touch and find out more about what options we offer.


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