How to Solder a Mini USB Port to a Circuit Board
By Kurt Schanaman
Updated December 17, 2018
Mini USB (Universal Serial Bus) port jacks are used in cell phones, card readers, digital cameras, and portable music players. Mini USB port jacks are installed onto circuit boards, and require you to exercise careful soldering techniques when soldering them to such boards. Careless soldering of the pins and feet by applying too much solder to any given joint can cause shorts between them, especially the pins. Selection of the soldering iron wattage and tip size are of utmost importance when soldering mini USB port jacks to circuit boards.
Items you will need
Tabletop clamp-on magnifying glass with built-in light (electronics supply stores)
Bottle of soldering flux (electronic supply stores)
1 round toothpick
Roll of rosin-core solder (electronic supply stores)
15-Watt pencil styled soldering iron with ultra-fine tip
Open the bottle of soldering flux and dip the tip of a round toothpick into the flux until the tip of the toothpick is wet but contains no actual drop of flux. Gently touch each of the mini USB soldering pads on the circuit board with the tip of the toothpick, allowing just enough of the flux to cover each of them until wet. Don't allow the flux wet the circuit board material between the metal soldering pads.
Clamp an adjustable lighted magnifying glass to the edge of the table or workbench where the soldering will take place. Position it directly over the circuit board so that the mini USB soldering pads are visible through the lens. Adjust the magnifying glass until you can see all of the pads comfortably.
Set the mini USB port jack onto the circuit board. By this time, the soldering flux should have dried slightly and will have a slight sticky consistency. This will assist in helping to keep the mini USB port jack in place on the board while soldering the initial foot. The mini USB port jack must be positioned so the five small pins on its back end line up with the five small soldering pins on the circuit board. Also the four small round feet should be lined up with their pads.
Let the 15-Watt soldering iron heat up about 15 to 20 minutes to reach maximum operating temperature. Just before you begin to solder, touch the tip of the solder wire to the tip of the soldering iron and allow the tip of the iron to become fully coated with a thin layer of solder. In the field of electronics, this necessary step is called "tinning the tip."
Hold the solder wire in one hand, and the soldering iron in the other. Gently lower the tip of the soldering iron onto one of the feet of the mini USB port jack, preferably one that is near the open socket end of the jack, not near the five small pins at the back. Touch the tip gently to the foot and allow to heat for no more than five seconds. With the tip of the soldering iron touching the foot, lower the tip of the solder wire until it briefly touches the heated foot. Allow just enough solder to flow so that it covers the foot and the pad on the circuit board, then lift both away with a direct upward motion. Allow this joint to cool for about two minutes before soldering the next foot.
Solder the second foot of the mini USB port jack just as with the first, and allow to cool for two minutes before soldering the final two feet to their circuit board soldering pads. Finish by soldering the last two feet, allowing them to cool for two minutes each after soldering each one.
Solder each of the five rear pins of the mini USB port jack to their small circuit board soldering pads and allow two minutes for each to cool before moving on to the next. When soldering these small pins, hold the soldering iron tip at a 45-degree angle and allow the slanted surface of the tip to lay over the length of the small foot at the end of each pin. Allow no more than five seconds to heat each of the pin feet. Gently touch the tip of the solder wire and allow a very small amount of solder to flow over the pin foot and its pad on the circuit board. Once solder begins to flow onto both, lift both the solder wire and the soldering tip straight upward and away. Solder each of the other feet, making sure no solder runs between the pin pads. You must be able to see bare circuit board between each of the soldered pins.
Gently remove any small solder splatters that may have accidentally formed between any two of the five rear pins during soldering. To remove, simply use the tip of a sewing needle to gently scrape the solder splatter out from between the two pins.
Mini USB port jacks are classified as SMD (Surface Mount Device) technology. SMD hand-soldering techniques apply to them.
Always allow at least two minutes for each solder joint to cool. There is a small plastic separator insert within the mini USB port jack that can overheat and melt if heat is applied continuously to the feet or pin pads without a break between, requiring you to start over with a new mini USB port jack.
Kurt Schanaman has had several editorials printed by the Star-Herald Newspaper publication in Western Nebraska. He attended Western Nebraska Community College.