The variety of SMD LEDs is expanding every day. SMD LEDs 3528, 2835, 5050, 3014, 5630 and 5730 are just the main sizes that have already gained worldwide popularity. In parallel with them, under the “Made in China” sign, planar LEDs of the most different sizes with unpredictable parameters.
If the time-tested characteristics of SMD 3528 and SMD 5050 LEDs, for the most part, correspond to the declared parameters, then there are many questions about light-emitting diodes of the new form factor. The Chinese have famously learned to counterfeit everything that is in demand in the consumer market, including LED products. Considering that LED bulbs and tapes from famous European companies are also assembled in China, what quality is included in them?
To clarify and see the differences among the most commonly used surface-mount LED chips today, we propose to compare their electrical, optical and structural parameters. But first, a few phrases about the scope of their application.
Application area
SMD LED is used wherever something needs to be illuminated, illuminated or simply decorated. They have become a basic element in general lighting bulbs, in indicator panels and LCD TVs, and in emergency lighting systems. The most popular product assembled using SMD LEDs is still the LED strip, as well as its modifications in the form of rulers and modules.
In the new variation, multi-color ribbons are constructed on groups that consist of four powerful LEDs different colors “R+G+B+W”. In total, their light output is much greater than that of conventional SMD 5050 LEDs, and the presence of an independent white LED expands the light shades.
Brief technical specifications
Now we will consider each of the most popular standard sizes individually. Using numbers, we will try to give an objective assessment of each type and reveal its strengths and weaknesses.
The manufacturing company has the right to change the opto-electrical parameters of SMD LEDs, indicating this in the passport data. For example, SMD 5730 from Samsung and Sanan will have slightly different luminous output.
Planar light-emitting diodes of this type can easily be called pioneers, thanks to them surface-mount technology has reached its current heights and continues to progress. LED SMD 3528 has a rectangular shape with an aspect ratio of 3.5 by 2.8 mm and a height of 1.4 mm. On each of the opposite sides of a shorter length, two contacts are visible. A cut (key) is visible on the casing from the cathode side. The working surface has a round shape, coated with phosphor.
The voltage drop at a nominal current of 20 mA depends on the color of the radiation. For white LEDs it can be in the range of 2.8-3.4V, and the luminous flux is 7.0-7.5 lm. The brightness of SMD 3528 is highly dependent on temperature and at 80°C it decreases by 25%.
This type of LED can be called an improved version of SMD 3528. The design of SMD 5050 made it possible to implement multi-color LEDs based on blue, red and green crystals with the ability to control each color separately. Inside the 5.0 by 5.0 mm case there are three crystals with technical parameters identical to SMD 3528.
Accordingly, the manufacturer does not recommend exceeding the operating current value more than 60 mA. In this case, the forward voltage will be 3.3V, and the luminous flux will be 18 lm. The total power consumption of one SMD 5050 is 200 mW in the operating temperature range -40/+65°C.
With LEDs, lighting devices have stepped into a new stage of development. In a case measuring 5.6 by 3.0 mm, scientists created not only a new form factor, but also semiconductor device with some design features, made using new materials. Unlike its predecessors, SMD 5630 is characterized by greater power and light output.
The luminous flux can reach 58 lm, measured at a forward current of 150 mA. Through proprietary SMD 5630 it is allowed to pass up to 200 mA DC and up to 400 mA pulsed current with a duty cycle of 25%. The magnitude of the forward voltage depends on the shade of white light and can range from 3.0 to 3.6V.
The SMD 5630 LED has 4 pins with a key near the first pin. Of these, only two terminals are used: 2 – cathode (-) and 4 – anode (+). Like many modern LED SMD chips, there is a substrate on the bottom that helps improve heat dissipation.
SMD 5730
Light-emitting diodes of this modification appeared almost simultaneously with the 5630 case and are their analogues. In turn, they are divided into two types: SMD 5730-05 and SMD 5730-1 with power consumption of 0.5 and 1.0 W, respectively. Both types are classified as highly efficient LEDs with a thermal resistance of only 4°C/W. Unlike SMD 5630, 5.7 by 3.0 mm LEDs are visually higher (by 0.5 mm) and, instead of four, have two contacts.
SMD 5730-05 can withstand currents up to 180 mA while dissipating 0.5 W of active power. It also works perfectly in pulse mode with a pulse amplitude of up to 400 mA, the duration of which is no more than 10% of the period. Working at nominal DC, SMD 5730-05 provides brightness up to 45 lm.
SMD 5730-1 can be operated at direct current up to 350 mA and pulsed current with a duty cycle of no more than 10% up to 800 mA. The typical voltage drop in the operating position is 3.2V with a power of up to 1.1 W. The crystal can withstand a p-n junction temperature of 130°C and functions normally in the range from -40 to +65°C. Compared to SMD 5050, it has lower thermal resistance and 6 times greater luminous flux, which in the proprietary version reaches 110 lm.
SMD 3014
SMD 3014 is a relatively new standard size belonging to the class of low-current LEDs. The maximum forward crystal current should not exceed 30 mA. Forward voltage zone 3.0–3.6V. White LEDs in warm shades have a minimum luminous output (8 lm), while cold LEDs have a maximum luminous output (13 lm). The dimensions of SMD 3014 are 3.0x1.4x0.75 mm. The anode and cathode leads are not limited to soldering at the ends. They go to the lower part of the body, which must be taken into account during manufacturing printed circuit board. The increased size of the contact pads improves heat dissipation and LED mounting. The anode lead is 2 times longer than the cathode.
The developers of SMD 2835 equipped it with the most best qualities that their predecessors had. The standard size 28 by 35 mm follows the shape of SMD 3528. But the new SMD 2835 has a much larger effective radiation area, which has a rectangular shape covered with phosphor. The element height is no more than 0.8 mm. Despite such small dimensions, the declared luminous flux can reach 50 lm.
In terms of other electrical characteristics, SMD 2835 is very similar to SMD 5730-05. In turn, the design of the element is identical to the SMD 3014 LED, when the anode and cathode terminals serve as a heat-sinking substrate.
Peculiarities
As we explore new Chinese SMD LED formats, this section can be expanded endlessly. For now, the most questions are about power consumption. By purchasing, for example, several SMD 5730 to assemble a lamp with your own hands or a ruler based on SMD 3014, the user expects to receive the luminous flux given in the data sheet. However, often a simple measurement of the load current and simple calculations show that the real power of one LED is 3–4 times lower. Why is that?
Because the size of 5.7 by 3.0 mm does not mean that the corresponding crystal is mounted inside. In this skillful way, the Chinese mislead buyers. The most interesting thing is that the buyer has practically no choice. Finding a branded product with the right parameters is difficult.
When designing a power supply with your own hands, you need to strive to ensure that the actual current in the load is approximately 95% of that specified in the technical specifications. By slightly underloading the LED, you can achieve an increase in operating life even in the case of low-quality Chinese LEDs.
For all LED models, luminous flux values are indicated for a color temperature of 5000–5500°K. Warmer tones will have 10% less light output, and cooler tones will have 10% more light output. In addition, it is worth remembering the error during testing, which can reach 7%. So don’t be surprised if instead of the stated 50 lumens, the chip produces no more than 43 lumens.
Before turning it on for the first time, always check the LED with a multimeter, since the pinout, in the case of a fake, may not match. Near the key there can be both the anode and the cathode of the chip.
In cheap monochromatic LED strips ah SMD 5050 you can see how all three chips of one LED are connected in parallel and powered by one resistor. This approach simplifies the layout of current-carrying tracks of a flexible printed circuit board, reduces the number of resistors used, and therefore reduces production costs. Of course, the service life of such a tape is also reduced.
Chinese craftsmen have learned to create SMD LEDs of any arbitrary shape, which can be easily verified. It is enough to remove the protective lens from several light bulbs from different companies (base E14, E27) and read the type of LED installed on the board. There seems to be no limit to the variety. Specifications It is impossible to predict such chips.
Read also
The luminous flux of the second generation of multi-chip LED assemblies of the Luxeon S family is 8000 lm. In addition, Philips Lumileds has resumed supply of blue LEDs in bulk and CSP (chip-scale package) sizes, which provide maximum flexibility for the manufacture of complex and densely packaged assemblies.
Thin Film Inverted Crystals
Lumileds has stopped supplying bulk blue LED chips, switching to a thin-film flip-chip architecture that eliminates the need to remove the sapphire substrate before packaging. With the advent of Flip-Chip LED components, the company developed an architecture in which a transparent substrate provides a stable position for the bare chip that manufacturers integrate directly into products.
The main advantage of the Flip-Chip architecture is the elimination of the use of thermocompression welding wire. This wire is not only possible reason failure, but also limits the placement of the LED chip and the LED driving current density. However, before the new design, Flip-Chip chips were too fragile to be sold in this form.
LED Flip-Chip from Lumiled
Now, luminaire manufacturers have the opportunity not only to install packaged LEDs in luminaires in the traditional way, but also to independently select the phosphor and housing for LED crystals in accordance with the requirements of the application.
Lumileds is the first manufacturer to develop and supply LEDs in CSP packages, which are essentially the same dimensions as the chips. Lumileds' Flip-Chip LED has a nearly identical footprint to the die. The only difference is the presence of pads at the base of the chip, which are optimized for standard reflow soldering processes. The degree of conversion of electrical energy into optical energy for a 1x1 mm crystal is 56-61%, depending on the wavelength. Lumileds traditionally does not specify the lumen output or efficiency of these LEDs, since emission at these wavelengths is in the reduced sensitivity range of the human eye.
Luxeon S multi-chip assemblies
Lumileds announced the second generation Luxeon S family of multi-chip components. The luminous flux density of these products reaches 50 lm/sq.mm, and their total luminous flux is 1000-1800 lm, depending on the design.
Second generation Luxeon S family of LED components
While the first generation Luxeon S products were designed as standard single light source assemblies in a small square package, the new products are essentially COB (chip-on-substrate) designs. Lumileds did not use COB labeling for these components, in part because these are LEDs with a phosphor that converts the light to white light, rather than an array of blue LEDs with a phosphor coating.
Rahul Bammi, vice president of Lumileds, clarified that the layout of the LEDs on the circuit board is designed in such a way as to provide the required beam angle. Among other applications, these assemblies are designed to replace 75- and 100-watt metal halide spotlights for retail stores.
The luminous flux density of the new assemblies is twice as high as the solutions offered on the market. The luminous flux of Luxeon S components reaches 8000 lm in half the size optical system, allowing these LEDs to be used to replace legacy ceramic metal halide lamps (CMHA) for directional lighting and architectural applications. At the same time, Luxeon S assemblies provide comparable light output of 90 lm/W, but, unlike KMGLs, they turn on instantly, have greater color saturation, and their service life is four times higher than that of KMGLs, amounting to 60 thousand hours.
The company claims that thanks to the LEDs used and their arrangement, the light intensity in the central part of the beam is 50 thousand cd. This solution is also color optimized across the entire emission angle. Lumileds offers LEDs with color temperatures of 2700 or 3000 K with a color rendering index of 80 or 90, and 3500-5000 K with a CRI of 80.
LEDs are becoming increasingly popular solutions in a variety of areas. They can be used as decorative products or for lighting indoors, as well as various areas outside buildings. LEDs are supplied to the market in a fairly wide range of modifications. At the same time, developers of relevant products periodically offer innovative solutions that in the future can create new market niches. What are the most common types of LEDs today? For what purposes can they be used?
What are LEDs?
Before looking at common types of LEDs, let's study general information about the corresponding devices. LED is a semiconductor that is capable of converting electricity into the world In this case, the semiconductor crystal, which is its main component, consists of several layers characterized by 2 types of conductivity. Namely - hole and electronic.
Conduction of the first type involves the transfer of an electron from one atom to another, which has a free place. In turn, another electron comes to the first atom, another one comes to the previous one, etc. This mechanism acts due to covalent bonds between atoms. In this case, they do not move. In fact, it moves positive charge, which physicists conventionally call a hole. In this case, when an electron passes to holes, light is released.
The structure of an LED is generally similar to a rectifier diode. That is, it has 2 terminals - anode and cathode. This feature predetermines the need to maintain polarity when connecting the LED to an electric current source.
In general, the corresponding products are designed for a forward current of 20 milliamps. In principle, this value can be reduced, although in this case the color may change and the brightness of the LED may decrease. In turn, it is undesirable to increase the corresponding parameter. If the current exceeds the optimal value, a limiting resistor is used to reduce it to the required level.
There are quite a few nuances that should be kept in mind when installing LEDs. It's predetermined by them internal structure, form of execution. In some cases, it may be necessary to use a stabilizer for LEDs and other electronic components to ensure the functioning of the device in which the product in question is installed.
Depending on the composition of the semiconductors in the LED, it can be red, yellow, green or blue. For example, if the structure of the corresponding electronic component contains gallium nitride, the LED will glow blue. Actually, one of the criteria based on which certain types of LEDs are distinguished may be their color.
Application
The first LEDs supplied to the market were produced in metal housings. Gradually it began to be replaced by plastic. In this case, the color is usually selected taking into account the color of the LED glow. However, transparent plastic cases are also quite common.
Considered electronic devices are widely used in a variety of fields. This is due to the fact that almost everyone is characterized by:
Energy efficiency;
Long service life;
The ability to determine the color of the glow, as well as adjust its power;
Security;
Environmentally friendly.
If we talk about energy efficiency, LEDs with the same luminous efficiency can have significantly less power than conventional lamps. The lower power of the LED reduces the overall load on the building's energy system. The service life of devices can be several tens of times longer than that of conventional lamps. At the same time, in terms of functions, LEDs can be completely on par with them.
As mass demand for such products develops, as well as their cost, LEDs are increasingly used for the same purposes as conventional lamps. There are no difficulties in installing the corresponding solutions in comparison with traditional lighting devices. It is only important to make sure whether a particular LED is suitable for installation in the electrical network of the room. To do this, it may be necessary to identify its main parameters in advance - before purchasing LEDs.
What other benefits might the solutions under consideration have?
So, it can be noted that Colorful temperature The LED can be almost anything - including a combination of the above colors. In addition, the devices can be supplemented with various light filters, which can significantly expand the scope of LEDs in terms of selecting the required color temperature.
The ability to control the glow power is another advantage of the devices in question. This option goes well with their high energy efficiency. LED power can be adjusted according to automatic mode- based on the actual conditions of use of lighting devices. And this practically does not affect their service life.
LEDs are environmentally friendly because they do not emit types of radiation harmful to humans. This characteristic, again, expands the possibilities of application of the devices in question.
Classification: indicator and lighting solutions
Experts distinguish 2 main categories of LEDs - indicator and lighting. The first ones are intended mainly for creating decorative light effect and are used as an element of decoration of a building, room, vehicle. Or as a tool for text stylization - for example, on an advertising banner.
In turn, there are lighting LEDs. They are designed to increase the brightness of lighting in a room or in a certain area of the territory - for example, if we consider LEDs for cars. This type of solution is an alternative to the use of conventional lamps and in many cases more beneficial in terms of energy efficiency and environmental friendliness.
Types of execution
But let's return to the classification of LEDs. It is possible to define a wide range of reasons for their classification into certain categories. A common approach among experts involves identifying the following main types of LEDs:
Fiber;
Let's take a closer look at them.
What are the specifics of DIP LEDs?
If we study in more detail how these types of LEDs appeared on the market, then DIP class devices can be attributed to the first that began to be sold en masse. These solutions are crystals that are placed in housings with optical components, in particular a lens that creates a light beam.
DIP LEDs belong to the indicator category. They have another name - DIL. They are installed on a board on which holes must first be made. It can be noted that within the category under consideration there may be Various types LEDs, which differ in bulb diameter, color, and material of manufacture. In this case, the corresponding parameters can be presented in the widest range. The shape of the solutions under consideration is cylindrical. Among the corresponding LEDs there are both monochrome and multicolor devices.
Spider LED
This type of LED is generally very similar to previous devices. But they have twice as many outputs - 4. While DIP LEDs have 2. The fact that the presented type of solution has more outputs optimizes heat dissipation and increases the reliability of the corresponding components. In practice, they are used in various fields, in particular as LEDs for cars.
SMD LEDs
These solutions are produced using the surface mounting concept. That is, they are LEDs installed on any surface, while other solutions can be installed through through-hole mounting.
The dimensions of LEDs of this type can be significantly smaller than those of alternative solutions, as well as the structures on which they are installed. Again, in this case it is legitimate to talk about more optimal heat removal. Using SMD LEDs in many cases it allows you to expand the variability of lighting designs.
SMD LEDs belong to the lighting category. They are characterized by a rather complex structure. So, the LED itself consists of a metal substrate. A crystal is fixed on it, which is soldered directly to the contacts of the substrate body. A lens is placed above the crystal. In this case, 1-3 LEDs can be installed on one substrate. SMD includes common types of ultra-bright LEDs, such as 3528. These solutions have high level demand.
COB LEDs
The next popular type of LED is COB. It is made using technology that involves installing the crystal directly on the board. This decision characterized by a large number of advantages:
Protection of the compound from oxidation;
Small design dimensions;
Heat dissipation efficiency;
Reducing the installation cost of LEDs - in comparison, in particular, with SMD-type devices.
If we consider the above types of LEDs, it can be noted that COB brand solutions can be classified as the most innovative. This technology was first implemented by Japanese engineers in the late 2000s. Now these types of LEDs continue to gain popularity.
According to experts, the solutions under consideration may even become the most popular on the market, especially if we talk about the commercial segment and the field of household lighting. It is worth noting that there are areas where the use of COB LEDs may be difficult. Among these are the production of professional lighting equipment. The fact is that the LEDs in question are not very optimal from the point of view of adapting to the organization of lighting with an established luminous intensity curve. In such cases, SMD type devices may be more suitable.
The diodes described are classified as lighting diodes. As experts note, they can be classified as the best based on the characteristics of the luminous flux. They are available in the market in different colors such as red, green, blue and also white. The luminous flux of these models has a dispersion angle of 40-120 degrees.
More than 9 COB LEDs can be installed on one substrate. They are coated with a phosphor, as a result of which they acquire high brightness. It can be noted that the luminous flux of these solutions is higher than that of SMD devices. Thus, if we consider which type of LEDs is better, then according to the specified criterion, a COB class solution may have an advantage.
COB LEDs are also used in the automotive industry. They can be used as a component of front, rear lights, and turn signals. The main thing is to install the purchased devices correctly. To do this, it makes sense to turn to experienced specialists.
Fiber LEDs
Fiber LEDs can be considered innovative. They appeared on the market recently, in 2015. The solutions in question were developed by engineers from South Korea.
These types of LEDs can be used in the production of clothing. That is, it is quite possible to make a shirt or T-shirt from them that can glow. The production of clothing based on fiber LEDs also involves the use of various polymers, as well as aluminum compounds.
Filament LEDs
Another example of innovative LEDs is Filament solutions. Their main advantage is high energy efficiency. For the same power, with LEDs such as COB, for example, Filament solutions can provide higher levels of illumination.
The one in question is most often used in the manufacture of one. Among the notable characteristics of the production of the corresponding LEDs is installation directly on a substrate made of glass. This approach makes it possible to distribute the light emitted by the LED over 360 degrees.
How to choose the best option?
How to determine the type of LED that is optimal for a particular design? There are a large number of criteria that you can focus on in this matter. In principle, it is quite legitimate to determine the scope of application of an LED based on its classification according to the characteristics that we discussed above. Let's study the specifics of choosing the appropriate electronic components, taking into account the characteristics of the devices:
Selecting LEDs: features of DIP solutions
As we noted above, DIP LEDs are among the earliest products to hit the market. Thus, they involve quite old, but still in demand technologies. Their main advantages are ease of installation, convenient form, low energy consumption, low heating, and also sufficient high degree protection from external influences.
Most often, the LEDs in question are available in diameters of 3 and 5 mm. If we compare LEDs by type, we can come to the conclusion that the solutions under consideration are the most optimal for use:
As elements of car tuning;
As decorative components;
As part of low-power - as an option for homemade - flashlights.
The LEDs in question have a relatively low cost and availability on the market. It can be noted that among the most common modifications are 12 volt LEDs. They can be present in various online catalogs, as well as specialized stores in a wide range. Actually, any 12 volt LEDs are characterized by a fairly high demand on the market.
Selecting LEDs: features of SMD type solutions
The appropriate type of solution for appearance fundamentally different from others in that they have a flat shape. These electronic components are mounted without the use of feet. The current for SMD type LEDs is supplied to the terminals that are located on their reverse side.
Thus, the installation of these devices is carried out without the use of holes. The placement of LEDs can be done very compactly. As a result, the structure on which the corresponding devices are located may also become smaller.
The main ways of using the devices in question are the same auto-tuning, various types of interior lighting. Among the most significant advantages of these options are high brightness and light output. In combination with small in size these solutions have significant advantages over alternative models products.
Among the most common on the modern market is the 3528 LED type. These products are widely used in the production of LED strips. The design of the corresponding products allows the production of three-color LEDs - with red, blue, and green glow colors. Many other electronic components are manufactured based on the 3528 type solutions, such as the SMD 5050 type LED.
The products in question are also characterized by their affordability. They are usually presented on the market in a wide range.
Selecting LEDs: Features of COB Solutions
First of all, it is worth noting that a significant part of the LEDs of the corresponding type are very powerful designs. Their characteristic feature- rapid dispersion of light, thanks to the placement of crystals on the surface, which provides dynamic heat dissipation.
The LEDs in question are very bright. This makes them in demand specifically for use in the design of car headlights. It is worth noting that these products should be installed taking into account a number of significant nuances - only experienced specialists can know these. Therefore, it is recommended to contact competent service personnel to install appropriate solutions.
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