Sunstone Pico DC and Micro E
By Andy Jensen
Once upon a time, the last chore of my day was to charge my phone. I’d struggle to find the charging cable amid a jumble of cables, books, and glasses and then struggle again to fit the end of the cable into my phone.
That was then. The now story is I place my phone on a charging pad and I’m done. I can place my wireless ear buds on the same pad and charge them, as well, which is a bonus.
Wireless power technology is projected to grow at 60% CAG through the 2020’s, according to New England Wire Technologies, a New Hampshire-based wire manufacture founded in 1898. Sales of wireless power technology is expected to reach USD $22 billion.
While the scientific principle of wireless charging technology has been around since the 19th century, the introduction and use of Litz wire has turned principle into profits. Litz wire is comprised of many, very thin strands of insulated wire weaved or twisted in a specific pattern. The pattern is key to how Litz wire minimizes loss from the skin effect and proximity effect.
Overcoming the Skin and Proximity Effect
The skin effect refers to the behavioral tendency of AC power to accumulate and travel on the peripheral edge of a wire, leaving the center nearly unused. As a result, the flow of power becomes congested, creating resistance. The Litz wire pattern directs the power to use wire more efficiently, thereby increasing capacity. Compared to other wire of the same diameter, Litz wire can be 20 times less resistant, an outcome that catches the attention of electronics manufacturers.
The proximity effect can also increase resistance by a factor of ten. In short, when current flows through a conductor, the current distribution will be constrained to smaller regions and thereby experience more resistance. Because a wireless power device is comprised of one or more conductors, the proximity effect poses a challenge to the device’s efficiency.
Litz wire resolves the challenges posed by the skin and proximity effects due to each strand of wire being insulated from the other. The individual insulation and pattern was a game changer.
Litz Wire: Every Rose has its Thorn
Three cheers for Litz wire! However, connecting Litz wire to a PCB board is another matter. Sure, with enough solder and a steady hand, the insulation from each wire can be melted away, leaving the wire firmly connected to the board. But soldering sucks. It’s hot, toxic, dirty, slow, and inefficient. In the R&D lab, soldering makes sense. On the production floor, soldering is a profit killer.
Welding eliminates the toxic and dirty conundrum, is significantly faster, and a process that neatly fits on any assembly line with added digital control.
Litz Wire Conquerer: The Picó DC
The ability to weld a Litz wire to a PCB board or other connection is possible with at least two other micro welding manufacturers. Avio and Amada both offer a welding configuration that will produce a satisfactory weld. Both companies introduced their systems long before wireless power started to become a thing.
Sunstone’s recent introduction of the Pico DC is a more modern and less expensive solution than the others. The Pico’s eight-inch color touchscreen interface may be reason alone for a manufacturer to prefer the Pico over the others. But when paired with Sunstone’s new Micro E weld head, the Pico monitors real-time displacement and force. When you factor in price, the Pico stands as a clear winner.
Sunstone reduced the cost of the Pico by combining all components into one unit, in addition to the weld head. The Avio and Amada configurations require multiple independent components, plus the weld head, which nearly doubles the price.
“The Pico’s closed-loop feedback, force, and displacement technology makes it an attractive welding solution,” says Jonathan Young, president of Sunstone Engineering. “In a fully automated environment, the Pico will significantly contribute to a manufacturer’s quality control efforts and save on capital equipment costs.”
Litz wire isn’t the only material the Pico seems to conquer with relative ease. Manufacturers who work with solar cells, PCB’s, magnet wire, coil terminations, electronics, heating elements, or fine ribbon bonding will find the Pico exceptionally valuable to their production processes.