Color temperature offset in COB packaging process of LED light source
With a bare chip package of COB technology is main chip and I/O terminals in the crystal above, when welding the conductive / thermal adhesive in PCB, with the bare chip after solidification, with Bonder wire (Al or Au) in ultrasound, hot pressing under the pad are respectively connected with the corresponding chip the I/O terminal pads and PCB, after passing the test, then the sealing resin.Compared with the traditional packaging technology, COB technology has the following advantages: low price, space saving, mature technology. The COB technology also has the insufficiency, namely needs to match the welding machine and the packing machine, sometimes the speed cannot keep up; the PCB patch is stricter to the environment request, cannot maintain and so on.Cob, this traditional packaging technology will play an important role in the packaging of portable products.
The baking temperature is too high, or the baking time is too long, which results in the denaturation of phosphor. LED quality is too bad. Consider CREE, Philips, Lumileds, OSRAM, LED.The so-called COB, that is, the bare chip with conductive or non conductive adhesive adhesion to the interconnect substrate, and then lead wire bonding to achieve its electrical connection. If the bare chip is exposed directly to the air and is susceptible to contamination or man-made damage, affecting or damaging the chip function, the chip is sealed with glue and bonded to the chip. People also call this package for the envelope.
The day 5000K up to 10000K, which is beyond the drift of gratitude, mainly produced by two problems:1, baking temperature is too high, or baking time is too long, resulting in phosphor denaturation.2, LED quality is too bad, consider trying CREE, Philips, Lumileds, OSRAM LED.
