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Surface-Mount Technology

Surface-mount Technology (SMT) may be easier than you think!

We have two kits in our “Learn to Solder SMT” series: the Blinky POV SMT, and the Blinky Grid SMT. They’re like our Blinky POV and Blinky Grid kits, only smaller, surface mount, and come with a pin and butterfly clasp so you can attach them to your lanyard, backpack, or whatever. The Blinky POV has 8 LEDs, and when you wave it through the air, the LEDs appear to paint in the air due to persistence of vision. It can show both simple images and text, and multiple messages can be stored in memory. The coolest part is that the kit is reprogrammed by typing in your new message or drawing the new image in a web page, and then holding the kit up to the screen. Two little boxes on the screen line up with optical sensors on the kit, and the black and white blinking of the squares transmits the message to the kit. There’s also a Larson Scanner in the Blinky POV firmware, so you can pin Cylon eyes onto whatever you’d like. The Blinky POV SMT is ideal for new SMT solderers–it only has a few components, and the chip is an easy-to-solder SOIC and all the other surface mount components are 1206 sized or bigger.

The Blinky Grid SMT is just like the Blinky POV SMT, only it has an 8×7 array of LEDs so the text and images can be scrolled or flash on the screen without needing to be swung through the air. It has the same easy-to-solder SMT components, only there are 56 LEDs instead of 8.

Learn more about our introductory Blinky SMT kits!

What is Surface-mount Technology?

Surface-mount Technology (SMT) is a method where electronic components are placed on a circuit board without legs that go through holes in the board.

There are a variety of packages and sizes that various surface mount components come in. They are usually smaller than through-hole components. Some are very very tiny and have pads that are underneath the device. Others are larger and have legs that stick out, while others are just flat rectangles with contact surfaces on both ends of the rectangle.

SMT sometimes has a reputation for being dark, deep magic that shouldn’t be attempted by mere mortals. This is usually not true.

What are some advantages to SMT?

SMT component usually cost less than their through-hole equivalents. They’re smaller, which may, depending upon your affinity for hoarding, may or may not translate into needing less space to store components around the house. Some newer components don’t have through-hole equivalents! Improving your SMT skills means you may be able to make your own breakout boards or evaluation boards for SMT components.

How can I learn to solder SMT?

There is a lot of information about SMT soldering on the internet. Our intent on these pages is to help explain what’s going on at an appropriate level of detail. We don’t want to bog anyone down. While it’s important to be informed, it’s easy to spend hours reading and watching videos about something you want to do, and never actually do it!

There are many valid ways to solder SMT in a hobbyist environment. Because SMT is more amenable to manufacturing than through-hole soldering, a lot of the rules and guidelines you may see are intended for large-scale manufacturing. At this scale, even a few boards needing human attention can add delays and incur extra costs for the manufacturer. When building boards by hand, many of these guidelines can be relaxed or even ignored completely.

There are two main techniques to hobbyist SMT soldering: hand soldering, and reflow.

Hand soldering uses an iron, solder, soldering wick, and sometimes flux. We have more information about hand soldering SMT, including tools and techniques.

Reflow often involves applying solder paste, which consists of little beads of solder suspended in flux, to the pads of the board, placing the components onto the pads, and then heating the assembly to melt the solder creating a joint. There are a variety of ways to apply the paste, and a variety of ways to heat the board. Because of surface tension, physics, and magic elves, during reflow, parts will “snap” into place even if they were relatively misaligned with the pads. It is hypothesized that the magic elves are related to the pixies that work inside zippers. [Citation needed] We have more information about soldering SMT using reflow, including tools and techniques.