Industry news

2016August

Sorting test of LED chip and device

From: www.szbako.com Data:29/08/2016

There are two ways of sorting

LED: one is based on the chip test, the two is the package of LED for testing and sorting.

(1) chip test sorting LED

chip sorting is very difficult, the main reason is that LED chip size is generally very small, from 9MIL to 14mil (0.22-0.35nm). Such a small chip requires micro probe to be able to complete the test, the sorting process requires a precise mechanical and image recognition system, which makes the device cost becomes very high, and the test speed is limited. Now the LED chip test sorting machine price is about 1 million yuan /Taiwan, the test speed of 10000 per hour or so. If calculated in accordance with the 25 days per month, each sorting machine production capacity of per month.

at present, testing and sorting chip has two methods: one method is completed by the same test sorting machine, it has the advantages of * * *, but the speed is very slow, low productivity; another method is completed by two test and sorting machine, position and parameter test equipment to record each chip then, the data is transferred to the sorting equipment, fast sorting, the advantage of this is fast, but the disadvantage is * * * is relatively low, prone to error, because between testing and sorting of two steps usually accompanied by thinning the substrate and the chip separation process, in this process, the epitaxial wafer there may be local fragmentation, fragmentation or incomplete local incomplete, making the actual chip distribution and storage in the sorting machine in the data does not match, resulting in difficulties. The key to solve the bottleneck problem of chip testing and sorting is to improve the uniformity of

. If a piece of wafer wavelength distribution within 2nm, brightness variations within + 15%, you can classify all the chips on the film as a file (bin), as long as through the test of the failure of the chip can be removed, will greatly increase the chip production and reduce chip cost. In case of uniformity is not very good, also can test and the & quot; more substandard products & quot; regions of the chip with ink smear disposed of, to quickly get to the & quot; qualified & quot; chip, but this cost is too high, put a lot of in line with the other guest requirements of the chip do not qualified certificate of waste treatment, final accounting of the cost of the chip may is unacceptable to the market level.

(2) LED after the test of the

package can be in accordance with the LED wavelength, light emission intensity, light emitting point of view, as well as the working voltage to test the separation. The result is led into many stall (bin) and categories, and then test sorting opportunities automatically according to a set of standard testing the LED packed in boxes with different bin. Because people are more and more high requirements for LED, the early sorting machine is 32Bin, and later increased to 64Bin, now has a commercial 72Bin sorting machine. Even so, sub LED Bin technical indicators still can not meet the needs of production and market. LED

test sorting machine is under a specific operating table current (such as 20mA), the LED test, generally will do a reverse voltage value of the test. Now the LED test sorting machine price is about 40~50 million yuan /Taiwan, the test rate of about 18000 per hour. If according to 25 days per month, 20 hours per day of working hours, each sorting machine production capacity of hours per month.

large display or other high-end customers, the quality requirements of LED. Especially in wavelength and brightness consistency of the requirements are very strict. If the LED packaging factory in buy chips did not put forward strict requirements, the packaging factory after a large number of package will find, packaged led in only a few number of products can meet the requirements of a customer, most of the rest will become in the warehouse inventory. This situation forced LED packaging factory, put forward strict requirements at the time of purchase LED chips, especially indicators of wavelength, brightness and voltage; such as, past the wavelength requirements

from the above on the LED and LED chip selection analysis can be seen, the more economical approach is to test the LED sorting. But due to the wide variety of LED, there are different forms, of shape, different size, different emitting angle, different customer requirements, different application requirements, which made completely through the LED test select the sorting of products become difficult to operate. And the application of LED is mainly distributed in the range of several wavelength and brightness segment, one package factory is very difficult to prepare all kinds of forms and types of LED. So the key back to the MOCVD epitaxial process, how to grow the wavelength and brightness of the LED epitaxial wafer is the key point to reduce the cost, the problem is not solved, LED production capacity and cost will still not fully resolved. But it is effective to solve the problem of fast and low cost chip sorting, which can be controlled by the uniformity of the epitaxial wafer.

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