The development of LED is attributed to the Japanese company in 1993 to achieve the mass production of blue chip, blue LED appeared, opened up a new field of human lighting, with the development of LED technology, LED plant lights in agricultural planting applications have also LED the era of innovation, LED plant lamp quality and LED lamp beads have a close relationship, So how to buy a good LED lamp bead has become the top priority, the following article will be from all aspects of the specific analysis, to help you understand LED more clearly and deeply, so as to choose the LED plant lamp bead suitable for the company’s products.

First, LED production process
The LED chip production process includes two aspects, one is epitaxial wafer growth, and the other is chip production.

LED epitaxial wafer growth technology mainly uses organic metal chemical vapor deposition (MOCVD) to produce epitaxial wafer with semiconductor luminous characteristics, epitaxial wafer is the raw material for manufacturing LED chips
Second, LED technical parameters
In the production process, the same batch of raw materials in the production process due to various reasons lead to the packaging of the finished product will have different quality, simply from the appearance and process can not be distinguished, the need for measurement technical support, for the application of plant lights, need to be purchased according to the plant light spectrum parameters.

Plant lamp is a product of spectral technology parameterization, the lamp beads used in plant lamps and lighting beads in the parameter expression is very different, the current LED packaging companies provide lamp bead parameters can not be suitable for the design parameters of plant lamps, this problem is due to the plant light spectrum test technology and plant light spectrum annotation parameters caused by the particularity of.

Plant lamp manufacturers in the purchase of lamp beads, need to transform the lamp bead lighting parameters into the spectral parameters of plant lamp beads, this parameter conversion process we call the spectral parameterization of plant lamp beads, plant lamp product design must use parameterized lamp bead parameters, otherwise the design index is not based on the realization.

The parameterized expression of lamp beads is very intuitive, such as:

QE1.042/645 nm / 3.28 V / 60 ma / 2835

Many technical products are parametric products, such as computer graphics cards, whose expressed parameters represent the performance and price of graphics cards.
Main parameters of plant light spectrum parameterization:

1, radiation power:

The radiant power of the LED lamp bead is the main indicator to determine the performance of the plant lamp product, the greater the radiant power, the higher the PPF value of the lamp bead, the better the radiation performance of the plant lamp.

The radiant power of the lamp bead is related to the chip area, the chip area is multiplied by the length and width of the chip, and the larger the chip area, the higher the radiant power.

The radiant power of the LED lamp bead is determined by the chip radiation power level and price, the larger the chip radiation power, the more expensive the price.
2, power consumption

LED lamp beads are divided into power levels according to the size of the current specifications, the larger the current specifications, the higher the power of the chip, but the greater the heat of the chip.

Different current specifications of the chip is packaged into different size specifications, such as: 2835,5730,3030, etc., the selection of different package specifications is based on the design requirements of the plant lamp structure, usually, low power chip efficiency and small heat.

3. Radiation efficiency

The radiant efficiency of the lamp bead = radiant power/power consumption *100%, and the radiant efficiency value is less than 100%.

Radiation efficiency expresses the proportion of radiation power generated per watt of electricity consumed, and the greater the radiation efficiency, the better.

Radiation efficiency is limited by semiconductor material production technology, but also by packaging technology and heat dissipation technology, the main reasons affecting radiation efficiency are:

The impact of chip manufacturing quality: different production equipment and chip technology affect the radiation efficiency of the chip, and the choice of brand chip manufacturers is an effective method.

Bracket material: At present, there are aluminum brackets, brass brackets, copper brackets on the market, aluminum brackets are the cheapest, copper brackets are the most expensive, even copper brackets, silver plating quality is also high and low; Packaging materials also include a variety of adhesive qualities for fixing and filling.

The quality of white light and rare earth technology is also affected by the quality of phosphor, and the high quality phosphor has low attenuation; White light phosphors are mainly divided into aluminate and silicate, aluminate performance is better than silicate, aluminate is the most representative of YAG, YAG performance is stable, low light decay, silicate itself chemical stability is poor, but brightness is higher than YAG.

Welding wire material: in addition to flip chip and CSP package, most of the lamp bead package is the use of gold wire welding process, the chip and the electrode of the support are connected, there are two kinds of alloy wire and pure gold wire on the market, pure gold wire is the best, gold wire according to the thickness and 0.7, 0.9, 1.0, 1.2, etc., the thicker the gold wire, the lower the heat group, the longer the lamp bead life.

4, PPF value: the PPF of the lamp bead needs special software to calculate, the power of the plant lamp is determined according to the PPF value of the LED lamp bead calculation, if the packaging company can not provide the PPF value of the lamp bead, it can not become a qualified plant lamp bead supplier.

5. MPF value: The measured value of photon flux with wavelength in the range of 380nm-800nm, in umol/s. For monochrome lamp beads, MPF=PPF; for fluorescent encapsulated lamp beads, MPF value is greater than PPF value. The parameter expression of fluorescent encapsulated lamp beads needs to be marked with MPF and PPF.

6. QE value: QE value is the PPF value per watt, which is derived from the spectral parameters of plant lamp beads, in umol/J. This parameter is a comprehensive index of plant lamp beads and the most important performance comparison index. QE value is a parameter that must be marked after the spectral parameterization of lamp beads. Measurement errors can lead to distortion of QE values.

7, radiation ratio: the relationship between the amounts of radiation in the defined band range, expressed in two ways.

Radiation content: A percentage of the total radiation in a certain band, radiation content is the weight of the radiation in a certain band in the total radiation.

Radiation ratio: The ratio between two bands, the radiation ratio is the unit weight of each other, usually R: B and R: FR.

The radiation ratio is only effective for the lamp beads of white light and rare earth process, and there is no radiation ratio for monochromatic light.

8, voltage division specifications: that is, the voltage division of the chip, such as 3.0V-3.15V, for the light source connected in series and parallel, the voltage division is controlled within 0.15V, so that the current distribution of each series of light source is uniform, which is conducive to improving the life of the light source.

9, color temperature classification: for the color separation of white light beads, the packaging factory needs to provide the BIN code of color temperature, the plant lamp uses white light for color separation requirements are relatively not strict, and the use of color BIN can be properly relaxed.

3. Evaluation rules
1. Evaluation rules of spectral parameters of lamp beads

The radiation efficiency of the lamp bead is the basis of the spectral parameters. When the radiation efficiency is the same, the comparison of PPF, MPF and QE is meaningful.

QE will tend to distort with the increase of green light radiation content, and for monochromatic light beads, the greater the QE, the better.

At present, the QE of LED lamp beads has not exceeded 2.2umol/J, and the QE parameters of any test analysis are close to this upper limit, and the error between the test method and the measurement data needs to be evaluated.

In the future, when LED lamp bead QE crosses 2.2umol/J, LED plant lights will enter the full application environment, other light sources will gradually withdraw from the application, plant light spectrum technology QE to reach 3.0umol/J as the research goal in the next few years.

2, LED lamp beads in the plant lamp application rules

The drive current of the LED lamp bead is best not to exceed the specification current, the current specification of the chip is close to the upper limit of the chip, although the drive current can be increased by improving the heat dissipation to obtain a higher PPF value, at the same time, the power of the lamp bead is also increased, the increase in PPF and power is not linear, the result is that the QE value is reduced.

The mechanism of this phenomenon is that after increasing the current, the recombination rate of electronic holes decreases, the lattice defect of the chip begins to prominent, and the heat of the chip increases, resulting in a decrease in the radiation efficiency of the chip, the increase in power consumption is higher than the increase in PPF, and the QE value of the plant lamp decreases.

A good design is to find the top priority between the heat dissipation index and the radiation efficiency of the lamp, rather than using a costly radiator to increase the power of the light source, and the result is often to reduce the QE index after increasing the power.

Making good lamp beads into poor products is a phenomenon I often see, and some plant lamps make QE1.3 of lamp beads into QE0.8 of plant lamps. If the QE of plant lamps is below 0.7, I suggest using cheap lamps. These problems arise because companies have not established the concept of spectral parameterization.

Tip: Reducing the driving current of the lamp bead is an effective way to obtain a higher QE value.

LED lamp bead is a current device, as far as possible to choose a lower junction voltage (Vf), you can increase the QE value accordingly, lower Vf can also reduce the heat of the lamp bead, high-power plant lamp selection of Vf is particularly important.

The radiation efficiency of the lamp bead determines the heat output of the plant lamp, and the heating power of the lamp bead = (1- radiation efficiency ratio) * electrical power.

The radiation efficiency value can be checked by testing and calculating the actual thermal power of the lamp bead.

Under the premise of spectral design ability, the discontinuous spectrum using monochromatic lamp bead ratio can be guaranteed in the light decay index. When using continuous spectrum lamp beads, the light decay index and blue shift index are the first factors to consider, but the price ratio of continuous spectrum lamp beads is advantageous.

Continuous spectrum needs to pay attention to R: B and R: FR indicators, at the same time, the amount of green radiation will cause QE distortion.

The measurement parameters of the lamp bead are limited by the limit parameters, and any test data close to the limit parameters need to be evaluated by a professional evaluation body and cannot be easily trusted.

LED lamp bead measurement parameter anomaly is mainly to observe the radiation efficiency and QE value, QE value is more intuitive, and the anomaly of these two indicators needs to be re-measured.

I am most worried about the measurement error and virtual label of the LED chip, I have always emphasized that the plant lamp is a parametric product, the plant lamp is sold is the spectral parameters, spectral parameters distortion, the planting effect is out of the question.

For measurement errors and imaginary parameters, my spectral design theory sets up a detection link, that is, XD factor. Through XD factor, we can measure its illuminance value and convert it into PPFD with XD factor, and use this PPFD to verify whether QE is accurate. This is the innovation of our plant light spectrum technology. The closed-loop design theory ensures the accuracy of plant light spectrum parameters more reliably.

3, LED lamp bead procurement cost

For the procurement of lamp beads, the most concerned is the price of lamp beads, usually people compare the price of similar packages, we provide a calculation formula for the price of lamp beads, can easily compare the advantages and disadvantages of product prices.

The price/performance ratio of the lamp bead =QE/ price, which indicates the QE value bought by the unit price.

The high cost performance means that the QE value obtained per unit price is large

For SMD packages, the price is recommended in the corner.

For COB packaging, the price is recommended in yuan.

Master the above knowledge points, the parametric concept of plant lamp will be clearer, I believe that the procurement and evaluation of plant lamp beads will be of great help, so as to improve the market competitiveness of plant lamp.

Plant lamps are spectral technology parameterized products, should use professional spectral parameters to describe the product and marketing, so that those fake and shoddy products can not flood the market, and jointly maintain the healthy development of the plant lamp industry.