First of all, we need to understand that the chip is a circular wafer before it is cut into a grain. After cutting, a manufacturer will reset the parameters. The cut wafer will be screened again according to voltage, brightness, wavelength and other parameters. The chip with the same parameters will be selected to another one according to a certain number. On the membrane (usually arranged as squares or rectangles on the membrane), this kind of film is generally called a square piece.
The wafer is easy to understand. After the circular wafer is cut, it will not be selected separately at all. A round chip film will be shipped directly, so it is generally called a wafer.
Square film
The square chip is the finished product finally shipped by the chip factory. It is classified according to the brightness, band, voltage and ESD level. It is a regular product with neat and uniform parameters. It has quality assurance and is called Sorted Chip in English. After making lamp beads in this level of chip packaging factory, brightness, colour, voltage consistency is high; quality Stable; lamp beads of superior quality; the BINs shipped to the packaging factory are relatively concentrated, generally two or three main BINs; customers will like it; because the colour of the finished product has high brightness consistency, and the performance of the finished product is stable; of course, the unit price will also be relatively high; it belongs to superior quality.
Shard
LED wafers are semi-finished products that are directly sold after the epitaxial sheet is cut by a good electrode without grading according to the parameters listed in the LED square above. Generally speaking, it is a secondary chip that the manufacturer believes that it is not worth sorting after testing and sells at a direct price. It is called a circle because the chips are arranged in a circle The film is called COT (Chips on tape) in English.
Epitaxial film
The epitaxial sheet is the finished product of the epitaxial manufacturer after the substrate has a light-emitting layer after passing through MOCVD. At present, it has 2-inch, 4-inch and 6-inch specifications.
The brightness, colour, voltage and consistency of this chip are not as good as the squares above. After the packaging factory is made into lamp beads, more BINs will be shipped; it is more difficult to ship the lamp beads in the packaging factory. When you go to the finished factory, you have to accept a wider range of BINs, which may require high consistency for colour The finished lamps, such as panel lamps, are not easy to accept; the advantage price is relatively cheap.
There is also a kind called LED film.
The chip belongs to the lowest-level chip, that is, the chip manufacturer selects the chip according to a certain standard (brightness, band, voltage, ESD, etc.) in the chip before shipment, which is called LED wool.
This kind of chip is garbage disposal, encapsulated into lamp beads as long as it can light up, regardless of voltage and colour consistency; for low-end products, the unit price is extremely cheap.
