One-hundred-and-thirty years ago, Thomas Edison completed the very first successful sustained test of the incandescent bulb. With a few incremental improvements in the process, Edison’s basic technology has lit the entire world ever since. This is about to change. We are on the cusp of a semiconductor-based lighting revolution that will ultimately replace Edison’s bulbs with a far more energy-efficient lighting solution. Solid state LED lighting could eventually replace almost all the countless billions of incandescent and fluorescent lights in use around the globe today. In reality, as a step along this path, President Obama last June introduced new, stricter lighting standards which will support the phasing out of incandescent bulbs (which already are banned in areas of Europe).
To know precisely how revolutionary led power supply module are as well as why these are still expensive, it is actually instructive to look at the way they are made and to compare this for the manufacture of incandescent light bulbs. This short article explores how incandescent lights are produced and then contrasts that process using a description of the typical manufacturing process for LED light bulbs.
So, let’s start with examining how traditional incandescent lights are produced. You will find that it is a classic illustration of a computerized industrial process refined in over a century of experience.
While individual incandescent light bulb types differ in proportions and wattage, all of them hold the three basic parts: the filament, the bulb, and also the base. The filament is made from tungsten. While very fragile, tungsten filaments can withstand temperatures of 4,500 degrees Fahrenheit and above. The connecting or lead-in wires are usually made of nickel-iron wire. This wire is dipped right into a borax answer to make the wire more adherent to glass. The bulb itself is made of glass and has a mixture of gases, usually argon and nitrogen, which boost the lifetime of the filament. Air is pumped out of the bulb and substituted with the gases. A standardized base supports the entire assembly in place. The base is called the “Edison screw base.” Aluminum is utilized on the outside and glass used to insulate the inside the base.
Originally made by hand, light bulb manufacturing is currently almost entirely automated. First, the filament is manufactured utilizing a process called drawing, where tungsten is combined with a binder material and pulled via a die (a shaped orifice) right into a fine wire. Next, the wire is wound around metallic bar known as a mandrel in order to mold it into its proper coiled shape, and then its heated in a process known as annealing, softening the wire and makes its structure more uniform. The mandrel is then dissolved in acid.
Second, the coiled filament is attached to the lead-in wires. The lead-in wires have hooks at their ends that are either pressed over the end of the filament or, in larger bulbs, spot-welded.
Third, the glass bulbs or casings are made utilizing a ribbon machine. After heating in a furnace, a continuous ribbon of glass moves along a conveyor belt. Precisely aligned air nozzles blow the glass through holes inside the conveyor belt into molds, creating the casings. A ribbon machine moving at top speed can produce more than 50,000 bulbs hourly. Following the casings are blown, they may be cooled and after that cut from the ribbon machine. Next, the inside of the bulb is coated with silica to eliminate the glare caused by a glowing, uncovered filament. The label and wattage are then stamped onto the outside surface of each casing.
Fourth, the bottom of the bulb can also be constructed using molds. It is produced with indentations within the shape of a screw so it can certainly match the socket of any light fixture.
Fifth, after the filament, base, and bulb are created, they are fitted together by machines. First, the filament is mounted to the stem assembly, using its ends clamped for the two lead-in wires. Next, the environment in the bulb is evacuated, and the casing is full of the argon and nitrogen mixture.
Finally, the base and also the bulb are sealed. The base slides onto the end of the glass bulb in a way that not one other material is necessary to keep these together. Instead, their conforming shapes permit the two pieces to become held together snugly, with all the lead-in wires touching the aluminum base to make certain proper electrical contact. After testing, bulbs are put inside their packages and shipped to consumers.
Light bulbs are tested for both lamp life and strength. In order to provide quick results, selected bulbs are screwed into life test racks and lit at levels far exceeding normal. This provides a precise measure of how long the bulb can last under normal conditions. Testing is performed whatsoever manufacturing plants along with at some independent testing facilities. The average life of the standard household bulb is 750 to one thousand hours, depending on wattage.
LED lights are built around solid-state semiconductor devices, so the manufacturing process most closely resembles that used to make electronic items like PC mother boards.
A mild-emitting diode (LED) is actually a solid state electrical circuit that generates light from the movement of electrons in a semiconductor material. LED technology has been around since the late 1960s, but also for the first forty years LEDs were primarily used in electronics devices to change miniature bulbs. Within the last decade, advances within the technology finally boosted light output sufficient for LEDs to begin to seriously contest with incandescent and fluorescent light bulbs. As with many technologies, as the expense of production falls each successive LED generation also improves in light quality, output per watt, and also heat management.
The computer market is well suitable for manufacture LED lighting. The procedure isn’t a lot different than building a computer motherboard. The companies making the LEDs themselves are generally not in the lighting business, or it is a minor part of their business. They are generally semiconductor houses which can be happy cranking out their product, which is the reason prices on high-output LEDs has fallen so much in the last fifteen years.
LED bulbs themselves are expensive to some extent as it takes several LEDs to obtain wide-area illumination rather than a narrow beam, and the assembly cost increases the overall price. Additionally, assemblies composed of arrays of LEDs create more opportunities for product defects.
An LED light contains four essential components: an LED circuit board, a heatsink, an electrical supply, along with a shell. The lights start out as bare printed circuit boards (PCB) and high luminance LED elements arrive from separate factories which specialize in making those components. LED elements themselves create some heat, and so the PCB utilized in lighting is special. Instead of the standard non-conductive sandwich of epoxy and fiberglass, the circuit board is organized over a thin sheet of aluminum which works as a heatsink.
The aluminum PCB utilized in LED lights are coated with a non-conducting material and conductive copper trace lines to create the circuit board. Solder paste will be applied within the right places and then Surface Mount Technology (SMT) machines place the tiny LED elements, driver ICs, along with other components on the board at ultra high speeds.
The round form of a conventional bulb implies that most LED printed circuit boards are circular, so for ease of handling several of the smaller circular PCBs are combined into one larger rectangular PCB that automated SMT machinery are prepared for. Think of it just like a cupcake tray moving from a single machine to the next along a conveyor belt, then at the conclusion the individual cupcakes are snapped free from the tray.
Let’s check out the manufacturing steps for any typical LED light designed to replace a regular incandescent bulb with the Edison Screw. You will see that this is a completely different process from your highly automated processes used to manufacture our familiar incandescent bulbs. And, despite everything you might imagine, folks are still very much an essential element of manufacturing process, and not just for testing and Quality Assurance either.
Once the larger sheets of LED circuit boards have passed through a solder reflow oven (a heat furnace that melts the solder paste), they are split up to the individual small circuit boards and power wires manually soldered on.
The little power supply housed within the body from the light experiences an identical process, or may be delivered complete from another factory. Either way, the manufacturing steps are identical; first the PCB passes through SMT lines, this goes to a manual dual in-line package (DIP) assembly line when a long row of factory workers add one component at the same time. DIP refers to the two parallel rows of leads projecting from your sides from the package. DIP components include all integrated chips and chip sockets.
While Leds burn many times over incandescent or CFLs and require not even half the power, they require some form of passive heatsink maintain the high-power LEDs from overheating. The LED circuit board, which is manufactured out of 1.6-2mm thick aluminum, will conduct the temperature from your dozen roughly LED elements for the metal heatsink frame and thus keep temperatures under control. Aluminum-backed PCBs are occasionally called “metal core printed circuit boards,” despite the fact that made of a conductive material the white coating is electrically isolating. The aluminum PCB is screwed in place inside the heatsink which forms the low half of the LED light bulb.
Following this, the power connector board is fixed in place with adhesive. The little power supply converts 120/240V AC mains capability to a lesser voltage (12V or 24V), it suits the cavity behind the aluminum PCB.
Shell assembly consists of locking the shell in position with screws. A plastic shell covers the energy supply and connects with all the metal heatsink and LED circuit board. Ventilation holes are included to enable hot air to escape. Wiring assembly for plug socket requires soldering wires for the bulb socket. Then shell is attached.
Next, the completed LED light is brought to burn-in testing and quality control. The burn-in test typically will last for 30 minutes. The completed LED light will then be powered up to see if it is in working order and burned set for 30 minutes. Additionally there is a high-voltage leakage and breakdown test and power consumption and power factor test. Samples from the production run are tested for top-voltage leaks, power consumption, and power factor (efficiency).
The finished bulbs pass through one final crimping step because the metal socket base is crimped in position, are bar-coded and identified with lot numbers. External safety labels are applied and the bulb is inked with information, including logo and model number. Finally, all that’s left is always to fix on the clear plastic LED cover which can be glued in position.
After a final check to make sure all the different elements of the LED light are tight, then it is packed into individual boxes, and bulbs are shipped out.
So, for those who have wondered why LED lights are really expensive today, this explanation of how they are manufactured and exactly how that compares to the creation of traditional light bulbs should help. However, it jrlbac reveals why the cost will fall pretty dramatically on the next several years. Just as the cost of manufacturing other semiconductor-based products has fallen dramatically as a result of standardization, automation and other key steps across the manufacturing learning curve, the same inexorable forces will drive on the costs of LED light bulb production.