One-hundred-and-thirty years ago, Thomas Edison completed the very first successful sustained test of the incandescent light bulb. With some 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 which will ultimately replace Edison’s bulbs with a far more energy-efficient lighting solution. Solid state LED lighting will ultimately replace almost all of the hundreds of vast amounts of incandescent and fluorescent lights in use around the globe today. Actually, as being a step along this path, The President last June unveiled new, stricter lighting standards that will support the phasing out of incandescent bulbs (which already are banned in areas of Europe).
To understand just how revolutionary led power supply module are along with why they are still expensive, it is actually instructive to consider the way that they are made as well as compare this towards the creation of incandescent light bulbs. This article explores how incandescent bulbs are made and then contrasts that process having a description of the typical manufacturing process for LED bulbs.
So, let’s start with examining how traditional incandescent light bulbs are made. You will find that it is a classic example of a computerized industrial process refined in spanning a century of experience.
While individual incandescent light bulb types differ in size and wattage, all of them have the three basic parts: the filament, the bulb, and also the base. The filament consists of tungsten. While very fragile, tungsten filaments can withstand temperatures of 4,500 degrees Fahrenheit and above. The connecting or lead-in wires are typically made from nickel-iron wire. This wire is dipped into a borax means to fix make the wire more adherent to glass. The bulb itself is made from glass and contains a mixture of gases, usually argon and nitrogen, which increase the lifetime of the filament. Air is pumped out of the bulb and replaced with the gases. A standardized base holds the entire assembly in position. The base is called the “Edison screw base.” Aluminum is used 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Originally made by hand, light bulb manufacturing is currently almost entirely automated.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 employing a process known as drawing, in which tungsten is blended with a binder material and pulled by way of a die (a shaped orifice) into a fine wire. Next, the wire is wound around a metal bar known as a mandrel so that you can mold it into its proper coiled shape, and then its heated in a process called 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 which can be either pressed on the end in the filament or, in larger bulbs, spot-welded.
Third, the glass bulbs or casings are designed 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 inside the conveyor belt into molds, creating the casings. A ribbon machine moving at top speed can produce greater than 50,000 bulbs per hour. After the casings are blown, they are cooled and after that cut off the ribbon machine. Next, the inside of the bulb is coated with silica to eliminate the glare the result of a glowing, uncovered filament. The label and wattage are then stamped on the outside top of each casing.
Fourth, the base of the bulb is additionally constructed using molds. It is made with indentations in the form of a screw to ensure that it can simply match the socket of the light fixture.
Fifth, when the filament, base, and bulb are created, they are fitted together by machines. First, the filament is mounted for the stem assembly, using its ends clamped for the two lead-in wires. Next, the environment inside the bulb is evacuated, and also the casing is stuffed with the argon and nitrogen mixture.
Finally, the base and the bulb are sealed. The base slides to the end from the glass bulb such that not one other material is needed to keep them together. Instead, their conforming shapes permit the two pieces to be held together snugly, with all the lead-in wires touching the aluminum base to make certain proper electrical contact. After testing, bulbs are placed inside their packages and shipped to consumers.
Bulbs are tested for 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 an accurate way of measuring how much time the bulb can last under normal conditions. Testing is performed whatsoever manufacturing plants along with at some independent testing facilities. The average lifetime of the standard household bulb is 750 to one thousand hours, depending on wattage.
LED bulbs are designed around solid-state semiconductor devices, therefore the manufacturing process most closely resembles that used to make electronic items like PC mother boards.
An easy-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, as well as the first forty years LEDs were primarily utilized in electronics devices to change miniature lights. Inside the last decade, advances in the technology finally boosted light output high enough for LEDs to begin with to seriously compete with incandescent and fluorescent lights. Just like many technologies, as the cost of production falls each successive LED generation also improves in light quality, output per watt, as well as heat management.
The pc market is well suited to manufacture LED lighting. This process isn’t a great deal diverse from making a computer motherboard. The businesses making the LEDs themselves are generally not in the lighting business, or it really is a minor a part of their business. They are usually semiconductor houses which can be happy cranking out their product, which is why prices on high-output LEDs has fallen a great deal within the last 15 years.
LED bulbs themselves are expensive in part since it takes a number of LEDs to have wide-area illumination as opposed to a narrow beam, as well as the assembly cost enhances the overall price. Furthermore, assemblies consisting of arrays of LEDs create more opportunities for product defects.
An LED light consists of four essential components: an LED circuit board, a heatsink, an electric power supply, along with a shell. The lights start off 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 a little bit of 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 presented on a thin sheet of aluminum which acts as a heatsink.
The aluminum PCB used in LED lights are coated using a non-conducting material and conductive copper trace lines to create the circuit board. Solder paste is then applied within the right places and after that Surface Mount Technology (SMT) machines place the tiny LED elements, driver ICs, along with other components onto the board at ultra high speeds.
The round shape of a conventional light implies that most LED printed circuit boards are circular, so for easy handling some of the smaller circular PCBs are combined into one larger rectangular PCB that automated SMT machinery are designed for. Think of it such as a cupcake tray moving in one machine to the next along a conveyor belt, then at the end the person cupcakes are snapped free of the tray.
Let’s have a look at the manufacturing steps to get a typical LED bulb meant to replace a regular incandescent bulb with the Edison Screw. You will find that it is a completely different process from your highly automated processes employed to manufacture our familiar incandescent bulbs. And, despite everything you might imagine, folks are still greatly an essential a part of manufacturing process, and not merely 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), these are separated in to the individual small circuit boards and power wires manually soldered on.
The tiny power supply housed in the body from the light bulb goes through a comparable process, or could be delivered complete from another factory. In either case, the manufacturing steps are identical; first the PCB passes through SMT lines, it goes to a manual dual in-line package (DIP) assembly line when a long row of factory workers add one component at a time. DIP means the two parallel rows of leads projecting through the sides from the package. DIP components include all integrated chips and chip sockets.
While Leds burn repeatedly longer than incandescent or CFLs and require not even half the energy, they want some type of passive heatsink maintain the high-power LEDs from overheating. The LED circuit board, which is made from 1.6-2mm thick aluminum, will conduct the temperature from your dozen roughly LED elements towards the metal heatsink frame and so keep temperatures in balance. Aluminum-backed PCBs are occasionally called “metal core printed circuit boards,” and though made of a conductive material the white coating is electrically isolating. The aluminum PCB is screwed set up inside the heatsink which forms the lower 50 % of the LED bulb.
After that, the energy connector board is fixed set up with adhesive. The tiny power source converts 120/240V AC mains power 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 ability supply and connects with the metal heatsink and LED circuit board. Ventilation holes are included to permit hot air to flee. Wiring assembly for plug socket requires soldering wires to the bulb socket. Then shell is attached.
Next, the completed LED light is delivered to burn-in testing and quality control. The burn-in test typically lasts for half an hour. The completed LED bulb will then be powered up to find out if it is working properly and burned set 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 pass through the last crimping step because the metal socket base is crimped in place, are bar-coded and identified with lot numbers. External safety labels are applied as well as the bulb is inked with information, such as brand 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 having a final check to make sure all the various parts 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 methods these are manufactured and how that compares to the creation of traditional lights should help. However, it jrlbac reveals why the price will fall pretty dramatically on the next couple of years. Just like the price of manufacturing other semiconductor-based products has fallen dramatically because of standardization, automation as well as other key steps over the manufacturing learning curve, the same inexorable forces will drive on the costs of LED light production.