The human eye color and brightness in the light belonging to the resolution is specially high, particularly for the color difference and changes are sensitive. Associated with efficiency and brightness LED constantly improved, and its application is much more and more widely. When LED as array display and display devices, as a persons eye for color and brightness of wavelength sensitivity, no separation of have LED evenly phenomenon and affect people's visual impact.
The wavelength and the inhomogeneity of brightness can give people produce uncomfortable feeling. According to the main wavelength, usually LED light intensity, light with brightness, color temperature, working voltage, reverse breakdown voltage several key parameters for testing and separation. LED test and also the sorting is LED production process of a typical necessary process. At present, it is many LED chips and packaging manufacturers the making capacity for the bottleneck, can be LED chip production and packaging costs important requirement.
1, LED the sorting method
LED, there's two ways of sorting: the actual first is the basic test chips for separation, and the second reason is to packaging good test LED satisfactions.
(1) the test chip satisfactions
LED chips sorting difficult, the major is the LED chips generally small size, from 9 mil to 14 mil (0.22-0.35 nm). Ordinary small chip need microprobe can carry out tests, sorting process requires precise machinery and image recognition system, which makes equipment cost becomes very tall, and test speed is constrained. Now the LED chips sorting machine test about value is one million yuan RMB, Taiwan, test speed per hour in about 10000 pets. If the calculated monthly 25 days, every station sorting machine capacity of 5 KK each and every month.
At present, the test chip sorting have 2 kinds of methods: a kind of method is tested together with same machine complete separation, its advantages is reliable, but slowly, productivity is low; Another way is to attempt and sorting by two machines completed, test equipment to record each chip position and parameters, then put these data transfer to the sorting equipment, the rapid separation, accomplish that advantage is rapidly, but its weakness is fairly low reliability, easy to make a mistake, because in test and separation between two steps typically a substrate thinning and chip the process of separation, and then in the process, the extension of may disintegrate, local incomplete or local fractured incomplete, makes all the actual chip distribution and storage in sorting machine data with discrepancies, cause difficulties sorting.
From grow at all solve bottle-neck separation test chip important to helping the extension of uniformity. Needs to be extension for the distribution within 2 nm wavelength in, the change of the brightness in within 15%, can will the film of all chip in substitution for a (Bin), as long as along with test of the unqualified chip can be removed, will greatly increase the production capacity of the chip decrease the cost of the daphnie. In the uniformity is not too good, can also be used to test and the 'unqualified products more' chip areas use inkjet blot out associated with dealing with drop, which quickly to wish 'qualified' chip, but systems work efficiently cost as well high, will put a lot of accord with other room requirements as not certification chip waste treatment, and finally a chip cost accounting may be market can't accept height.
(2) LED the separation test
After the encapsulation leds luminous intensity, according to the wavelength, the light and the Angle of test working voltage and sorting. It seems sensible LED in a very lot for the documents (Bin) and category, and then test sorting automatically in accordance with the chance setting the standard test LED in different Bin packing box. Because those LED to demand much more more, earlier sorting machine is 32 Bin, then increase to 64 Bin, there are increasingly over 72 Bin commercial sorting peice of workout equipment. Even so, points of Bin LED technology index still can't match the production along with the demand of the market.
Sorting machine is LED test from a particular workbench electricity flowing down the (such as 20 mA), LED to test, general will do a reverse voltage value of the test. The sorting machine now LED test about the price 40 ~ 500000 RMB/set, the test speed per hour in about 18000 dog's. If the 25 days a month, 20 hours every the working time among the calculation, every station sorting machine capacity of 9 KK every month.
Large screen or other high-end application customers, Contributed to the quality requirements of your higher. Particularly wavelength and brightness when needed consistency may be strict. If FengZhuangChang LED in chip purchasing will not put forward strict requirements, the FengZhuangChang in many of these shipped will find, encapsulation good only a small associated with LED numerous meet a person requirements, and a lot of the rest of the will become in the warehouse product. This situation forced LED FengZhuangChang in purchasing LED chip strict requirement put forward, especially the wavelength, the brightness and table of voltage index; For example, the past to request is + 2 nm wavelength, it truly is now necessary for the + 1 nm, or, in the most applications, has proposed + 0.5 nm requirements. So with the chip factory produce large amount of pressure, in the chip sales to strict separation in advance of.
From previously mentioned about LED and LED chip points can rise above the crowd in the analysis, comparative economic method is to test LED satisfactions. But because of the LED many different kinds quite a few form, not the form of the now, different size, different light Angle, different customer requirements, different application requirements, the use right end up being completely through test points LED by product separation is hard operate. As well as the applying LED mainly distributed globe few wavelengths segment and also the brightness for the section area, a FengZhuangChang hard to prepare all customer needs of the various forms and types of Light emitting diode. So the key to issue is and return the extension of MOCVD process, the right way to grow the appropriate wavelength and brightness LED extension is always to reduce the cost of the key point, this concern is not solved, LED the production capacity of the cost and still won't get completely settled. But in the extension on the homogeneous sum of get control before, efficient method is to solve rapidly low-cost chip sorting ailment.
2, sorting equipment
At present, LED chips sorting equipment testing usually by the us and Japan manufacturers to provide, and LED the sorting equipment testing coming from the Taiwan region, most manufacturers provide Hong Kong, mainland China can't provide similar equipment fully grasp. LED chips sorting machine mainly includes two hardware (machine hand, micro probes and photoelectric tester) and a few system software, the three parts by different manufacturers with respectively to integrated; And LED the test points, including the selection machine LED mechanical transmission, storage and parameter test two parts.
3, LED points selection technology development trend
(1) associated with extension of your homogeneous degree of get control before, r&d rapid low cost chip separating process and equipment.
(2) with the W level power LED technology development, the traditional LED products inspection standard parameters and test method can not meet the requirements of the lighting applications, it's vital to develop new test standards and methods, including more and lighting related optical video.
(3) in the LED systems in life test, developing LED system's long-term performance and life quickly determine evaluation methods.
(4) LED lighting inside large current drive to work, is actually important to to submitted higher element of the reliability. Traditional way of screening not appropriate LED lighting use high power LED, must develop new screening test method, eliminate early failure is tasted, guarantee the reliability for this product.