One-hundred-and-thirty years ago, Thomas Edison completed the first successful sustained test of the incandescent light bulb. With some incremental improvements along the way, Edison’s basic technology has lit the world ever since. This is going 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 will ultimately replace almost all the numerous vast amounts of incandescent and fluorescent lights in use all over the world today. In fact, as a step along this path, The President last June unveiled new, stricter lighting standards that can support the phasing out of incandescent bulbs (which already are banned in parts of Europe).
To comprehend just how revolutionary Mini power supply are in addition to why they are still expensive, it really is instructive to consider how they are manufactured and also to compare this for the output of incandescent lights. This post explores how incandescent light bulbs are made and then contrasts that process having a description from the typical manufacturing process for LED light bulbs.
So, let’s start with taking a look at how traditional incandescent light bulbs are produced. You will notice that it is a classic illustration of an automated industrial process refined in spanning a century of expertise.
While individual incandescent light types differ in proportions and wattage, all of them have the three basic parts: the filament, the bulb, as well as the base. The filament is made of tungsten. While very fragile, tungsten filaments can withstand temperatures of 4,500 degrees Fahrenheit and above. The connecting or lead-in wires are generally made of nickel-iron wire. This wire is dipped into a borax means to fix have the wire more adherent to glass. The bulb itself is made from glass and has a combination of gases, usually argon and nitrogen, which raise the life of the filament. Air is pumped out from the bulb and substituted for the gases. A standardized base supports the entire assembly in place. The base is known as the “Edison screw base.” Aluminum is utilized on the outside and glass utilized to insulate the within the base.
Originally produced by hand, light bulb manufacturing is now almost entirely automated. First, the filament is manufactured employing a process known as drawing, by which tungsten is combined with a binder material and pulled via a die (a shaped orifice) in to a fine wire. Next, the wire is wound around a metal bar referred to as a mandrel in order to mold it into its proper coiled shape, and then its heated in a process referred to as annealing, softening the wire and makes its structure more uniform. The mandrel will then be dissolved in acid.
Second, the coiled filament is linked to the lead-in wires. The lead-in wires have hooks at their ends that are either pressed over the end from the filament or, in larger bulbs, spot-welded.
Third, the glass bulbs or casings are made employing 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 within the conveyor belt into molds, creating the casings. A ribbon machine moving at top speed can produce greater than 50,000 bulbs hourly. After the casings are blown, they may be cooled then cut from the ribbon machine. Next, the inside of the bulb is coated with silica to remove the glare caused by a glowing, uncovered filament. The label and wattage are then stamped to the outside top of each casing.
Fourth, the base of the bulb is also constructed using molds. It is made with indentations in the form of a screw so that it can certainly fit into the socket of any light fixture.
Fifth, once the filament, base, and bulb are produced, they may be fitted together by machines. First, the filament is mounted for the stem assembly, using its ends clamped to the two lead-in wires. Next, air inside the bulb is evacuated, and also the casing is full of the argon and nitrogen mixture.
Finally, the base as well as the bulb are sealed. The base slides on the end of the glass bulb to ensure that no other material is needed to keep them together. Instead, their conforming shapes enable the two pieces to become held together snugly, with the lead-in wires touching the aluminum base to ensure proper electrical contact. After testing, bulbs are positioned within their packages and shipped to consumers.
Light bulbs are tested for both lamp life and strength. So that you can provide quick results, selected bulbs are screwed into life test racks and lit at levels far exceeding normal. This supplies an accurate way of measuring how long the bulb will last under normal conditions. Tests are performed in any way manufacturing plants along with at some independent testing facilities. The normal life of the typical household bulb is 750 to one thousand hours, depending on wattage.
LED lights are made around solid-state semiconductor devices, and so the manufacturing process most closely resembles that utilized to make electronic goods like PC mother boards.
A mild-emitting diode (LED) is actually a solid state electrical circuit that generates light through the movement of electrons in a semiconductor material. LED technology has been available since the late 1960s, but also for the first 4 decades LEDs were primarily used in electronics devices to change miniature light bulbs. Inside the last decade, advances inside the technology finally boosted light output high enough for LEDs to start to seriously contest with incandescent and fluorescent bulbs. As with many technologies, as the expense of production falls each successive LED generation also improves in light quality, output per watt, as well as heat management.
The computer market is well suited to manufacture LED lighting. This process isn’t a lot different than creating a computer motherboard. The firms making the LEDs themselves are generally not inside the lighting business, or this is a minor element of their business. They are generally semiconductor houses that are happy cranking out their product, which is the reason prices on high-output LEDs has fallen a lot during the last 15 years.
LED bulbs themselves are expensive partly as it takes several LEDs to obtain wide-area illumination as opposed to a narrow beam, as well as the assembly cost increases the overall price. Furthermore, assemblies comprising arrays of LEDs create more opportunities for product defects.
An LED light consists of 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 concentrate on making those components. LED elements themselves create some heat, and so the PCB used in lights is special. As opposed to the standard non-conductive sandwich of epoxy and fiberglass, the circuit board is laid out on the thin sheet of aluminum which works as a heatsink.
The aluminum PCB used in LED lighting is coated having a non-conducting material and conductive copper trace lines to make the circuit board. Solder paste is then applied within the right places then Surface Mount Technology (SMT) machines place the tiny LED elements, driver ICs, and other components on the board at ultra high speeds.
The round form of a regular bulb means that most LED printed circuit boards are circular, so for simplicity of handling several of the smaller circular PCBs are combined into one larger rectangular PCB that automated SMT machinery can handle. Consider it such as a cupcake tray moving from a single machine to another along a conveyor belt, then at the end the person cupcakes are snapped clear of the tray.
Let’s have a look at the manufacturing steps for any typical LED light bulb intended to replace a regular incandescent bulb with the Edison Screw. You will see that it really is a totally different process through the highly automated processes utilized to manufacture our familiar incandescent bulbs. And, despite what you might imagine, people are still greatly a necessary part of manufacturing process, and not just for testing and Quality Assurance either.
After the larger sheets of LED circuit boards have passed via a solder reflow oven (a heat furnace that melts the solder paste), they are split up into the individual small circuit boards and power wires manually soldered on.
The little power supply housed in your body of the light bulb goes through a comparable process, or could be delivered complete from another factory. In any case, the manufacturing steps are similar; first the PCB passes through SMT lines, then it goes toward a manual dual in-line package (DIP) assembly line where a long row of factory workers add one component at the same time. DIP refers back to the two parallel rows of leads projecting through the sides in the package. DIP components include all integrated chips and chip sockets.
While Leds burn many times longer than incandescent or CFLs and require not even half the vitality, they need some form of passive heatsink keep the high-power LEDs from overheating. The LED circuit board, which is made from 1.6-2mm thick aluminum, will conduct the heat through the dozen approximately LED elements for the metal heatsink frame and thus keep temperatures in balance. Aluminum-backed PCBs are often called “metal core printed circuit boards,” and though made of a conductive material the white coating is electrically isolating. The aluminum PCB is screwed in place within the heatsink which forms the lower half of the LED light.
Following this, the power connector board is fixed set up with adhesive. The little power supply converts 120/240V AC mains capability to a reduced voltage (12V or 24V), it fits in the cavity behind the aluminum PCB.
Shell assembly consists of locking the shell in place with screws. A plastic shell covers the power supply and connects with the metal heatsink and LED circuit board. Ventilation holes are included to enable heat to escape. Wiring assembly for plug socket requires soldering wires to 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 lasts for 30 minutes. The completed LED light bulb will be powered up to see if it is in working order and burned in for half an hour. 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 move through one final crimping step as the metal socket base is crimped in place, are bar-coded and identified with lot numbers. External safety labels are applied and also the bulb is inked with information, including brand name and model number. Finally, all that’s left would be to fix on the clear plastic LED cover that is glued set up.
After having a final check to ensure all the various 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 extremely expensive today, this explanation of how they are manufactured and just how that comes even close to the manufacture of traditional lights should help. However, it jrlbac reveals why the fee will fall pretty dramatically over the next several years. Just like the cost of manufacturing other semiconductor-based products has fallen dramatically due to standardization, automation and other key steps along the manufacturing learning curve, the same inexorable forces will drive down the costs of LED light bulb production.