The back end process is to start with the chips cut from the silicon wafer one by one, carry out the processes of chip loading, fixation, bonding connection, plastic potting, lead out the wiring terminal, press printing inspection and so on, and complete the packaging body as the components and parts, so as to ensure the reliability of the components and facilitate the connection with the external circuit.
Wafer Fabrication
Wafer fabrication is mainly the process of making circuits and embedded electronic components (such as transistors, capacitors, logic gates, etc.) on wafers. It is the process with the most complex technology and the most capital investment. Taking microprocessor as an example, it needs hundreds of processing steps, and the processing machines are advanced and expensive. Although the detailed processing procedures are constantly changing with the changes of product types and application technology, the basic processing steps are usually after the wafer is properly cleaned, followed by oxidation and deposition, and finally repeated steps such as lithography, etching and ion implantation, so as to finally complete the processing and fabrication of circuits on the wafer.
Wafer Probe
After the wafer is scribed, a small grid will be formed on the surface. Each small grid is a wafer or die, that is, an independent integrated circuit. In general, wafers made on one wafer have the same specification, but it is also possible to make wafers with different specification levels on the same wafer. When the wafer is screened by the probe, it will mark whether each wafer is qualified or not, so as to test whether each wafer is qualified or not; The second is to detect and group the electrical characteristics (such as power) of each wafer, and make corresponding distinguishing marks.
Chip Assemble
First, glue the cut wafer onto the substrate; Secondly, the bonding pad of the wafer is connected to the pin of the frame pad by using ultra-fine metal wire or conductive resin to connect the wafer with the external circuit to form a specific specification of integrated circuit chip (bin); Finally, the independent chip is encapsulated and protected with a plastic shell to protect the chip components from external force damage. After plastic packaging, a series of operations should be carried out, such as post mold cure, trim, form and plating.
Chip Test
After the encapsulated chip successfully passes through the burn in, it needs to conduct in-depth test, including initial test and final test. The initial test is to put the encapsulated chip in various environments to test its electrical characteristics (such as running speed, power consumption, frequency, etc.), select the failed chip, and divide the normal working chip into different levels according to the electrical characteristics. Finally, the test is to convert the chip after the initial test.
Finish Goods Warehousing
The tested chip enters the final end processing after passing through the semi-finished product warehouse, including laser printing, factory quality inspection, finished product packaging, etc., and finally enters the warehouse.
