LED wafer and LED chip

Some friends may not know the concept of LED wafer and LED chip. Simply put, any thin slice of crystal is called a wafer, and any small thin slice encapsulated in other structures can be called a chip.

1. Difference

1. LED wafer is the main raw material of LED, and LED mainly relies on wafer to emit light.

2. LED chip is a solid-state semiconductor device, which is a P-N junction, which can directly convert electricity into light. The heart of LED is a semiconductor wafer. One end of the wafer is attached to a bracket, one end is the negative pole, and the other end is connected to the positive pole of the power supply, so that the entire wafer is encapsulated by epoxy resin.

2. Composition

1. The composition of LED wafer: it must be composed of several elements of arsenic (AS), aluminum (AL), gallium (Ga), indium (IN), phosphorus (P), nitrogen (N), and strontium (Si).

2. The composition of LED chip: it is composed of gold pad, P pole, N pole, PN junction, and back gold layer (double pad chip has no back gold layer).

Semiconductor devices are generally made of crystal materials. During the manufacturing process, raw material wafers and thin sheets with functional layers are generally referred to as wafers. The so-called functional layer is generally a PN junction layer. For integrated circuits, there are also some small resistors and small capacitors (however, active devices are generally used to form resistors and capacitors. Although there are more components, it actually saves more chip area than making resistors and capacitors. Larger resistors and capacitors are usually connected externally).

When hundreds or thousands of independent devices or ICs are completed on a large round wafer, each device will be separated by dicing. These small wafers will eventually be packaged into practical devices. So these small wafers are called chips. Of course, it is not wrong to call the entire process from raw material wafers to completed device manufacturing chip manufacturing.

After semiconductor chips are packaged, they are called devices, and can no longer be called wafers or chips. Because semiconductor diodes, triodes, LEDs, etc. all contain PN junctions, which are essentially an electric field area, or a power supply area (solar cells such as silicon and gallium arsenide use the function of PN junctions), they are also called active devices. However, for users, it generally does not matter whether they understand and distinguish between active devices and passive components. (The concepts of components and devices are also different, but in fact, there is no great significance in distinguishing them.)