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What is the principle of chip packaging?

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One process of semiconductor sealing and testing is packaging, which is to protect the internal components of the products with serial gold wires through the melting of black glue. Why can’t the gold wires in the black glue be damaged when it flows? What is the working principle of its sealing cavity?

packaging with black glue refers to cob (chip on board) packaging
the cob packaging process is as follows:
Step 1: Crystal expansion. The whole LED chip film provided by the manufacturer is evenly expanded by the expander, so that the LED grains closely arranged on the film surface are opened for crystal pricking
Step 2: back glue. Put the crystal expanding ring with expanded crystal on the back glue machine surface with scraped silver paste layer and put silver paste on the back. Some silver paste. Suitable for bulk LED chips. Use glue dispenser to dot an appropriate amount of silver paste on PCB printed circuit board
Step 3: put the crystal expanding ring with prepared silver paste into the spinel frame, and the operator stabs the LED chip on the PCB printed circuit board with a spinel pen under the microscope
Step 4: put the pricked PCB printed circuit board into the thermal circulation oven and let it stand at a constant temperature for a period of time, and take it out after the silver slurry is solidified (do not leave it for a long time, otherwise the LED chip coating will be baked yellow, i.e. oxidized, causing difficulties for bonding). If there is led chip bonding, the above steps are required; If there is only IC chip binding, cancel the above steps
Step 5: stick the chip. Use a glue dispenser to put an appropriate amount of red glue (or black glue) on the IC position of PCB printed circuit board, and then use anti-static equipment (vacuum suction pen or sub) to correctly place the IC bare chip on the red glue or black glue
Step 6: drying. Put the bonded bare sheet into the thermal circulation oven and place it on the large plane heating plate at constant temperature for a period of time, or it can be cured naturally (for a long time)
Step 7: bonding (wiring). Aluminum wire bonding machine is used to bridge the wafer (LED grain or IC chip) with the aluminum wire of the corresponding pad on the PCB, that is, the inner lead of cob is welded
Step 8: pre test. Use special testing tools (COB has different equipment according to different purposes, and the simple is high-precision regulated power supply) to test cob board and repair the unqualified board again
Step 9: dispensing. The dispensing machine is used to place an appropriate amount of AB glue on the bonded LED grains, the IC is encapsulated with black glue, and then the appearance is encapsulated according to the customer’s requirements
Step 10: curing. Put the sealed PCB printed circuit board into the thermal circulation oven and let it stand at a constant temperature. Different drying times can be set according to the requirements
step 11: post test. The packaged PCB printed circuit board is then tested for electrical performance with special testing tools to distinguish between good and bad
Step 12: Polish. Polish according to the customer’s requirements for product thickness (generally soft PCB)
step 13: cleaning. Clean the product
step 14: air drying. Air dry the cleaned product twice
step 15: test. Success is determined in this step (there is no better way to remedy bad films)
step 16: cutting. Cut the large PCB into the size required by the customer
step 17: packaging and delivery. Package the product

the melting point of black glue is relatively low. When packaging, first package the wires with black glue, and then install the chip and other components that are easy to break. Add black glue once, because there is less black glue in the later filling, so as to ensure that the packaging will not damage the original.

Recommended cooperation partner: Bitto

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