The chip on board (Chip On Board, COB) packaging process is that first, the surface of the substrate is covered with a thermally conductive epoxy resin (generally epoxy resin with silver particles), and then the silicon wafer is placed indirectly on the surface of the substrate After heat treatment, the silicon wafer is firmly fixed on the substrate, and then the wire connection is used to indirectly establish the electrical connection between the silicon wafer and the substrate. The sealing process is as follows:
The first step: crystal expansion
The spreading machine is used to spread the zero-chi LED chip film provided by the manufacturer evenly, so that the LED crystals that are closely displayed on the surface of the film are pulled apart, which is convenient for thorn crystal.
Step 2: Adhesive
Place the crystal expansion ring of the enlarged crystal on the surface of the adhesive machine that has not scraped the silver paste layer, and put the silver paste on the back. Point silver paste. It is suitable for dismantling LED chips. Use glue dispenser to spot the right amount of silver paste on the PCB printed circuit board.
The third step: Put in the crystal rack
Put the expanded ring of the prepared silver paste outside the crystal rack, and the operator will pierce the LED chip with the crystal pen on the PCB printed circuit board under the microscope.
Step 4: Put in a thermal cycle oven
Put the crystal-printed PCB printed circuit board in a thermocycling oven and leave it at a constant temperature for a period of time, and then take it out after the silver paste is solidified (not for a long time, otherwise the LED chip coating will be yellowed, that is, oxidized, making bonding difficult). If there is no LED chip bonding, the above steps are required; if only the IC chip bonding is needed, the above steps are cancelled.
Step 5: Stick the chip
Use a dispenser to put an appropriate amount of red glue (or black glue) on the IC position of the PCB printed circuit board, and then use an antistatic device (solid air suction pen or female) to place the IC bare chip on the red glue or black glue accurately .
Step 6: Drying
Put the sticky die into a thermal cycle oven and place it on a large flat heating plate at a constant temperature for a period of time. It can also be cured naturally (long time).
Step 7: Bonding (playing wire)
Use an aluminum wire bonding machine to bridge the wafer (LED die or IC chip) with the corresponding pad aluminum wire on the PCB board, that is, the inner lead of the COB is welded.
Step 8: Pre-test
Use common testing tools (no different equipment for different COBs, simple is high-precision regulated current) to test the COB board, and return the unqualified board girl Shen Xin to repair.
Step 9: Dispense
Use glue dispenser to place the right amount of AB glue on the LED chip. The IC is sealed with black glue, and then the appearance is sealed according to customer requirements.
Step 10: curing
Put the sealed PCB printed circuit board in a thermostatic oven and place it at a constant temperature, and set different drying time according to the requirements.
Step 11: Post-test
Use the common testing tools to test the electrical performance of the sealed PCB printed circuit board, and distinguish between good and bad. With the advancement of science and technology, packages include aluminum substrate COB package, COB ceramic COB package, aluminum substrate MCOB package and other forms.
Product catagories of stylus pen for ipad, which is just for iPad Versions 2018 & 2019 and above.
It can work on following:
iPad 6th 2018: A1893/A1954
iPad 7th 2019: A2197/A2198/A2200
iPad 8th 2020: A2270/A2428/A2429/A2430
iPad air 3rd: A2152/A2153/A2154/A2123
iPad Air 4th: A2072/A2316/A2324/2325
iPad mini 5th: A2124/A2125/A2126/A2133
iPad Pro 1st/2nd 11: A1980/A2013/A1934/A1979/A2228/A2068/A2230/A2231
iPad Pro 3rd/4th 12.9: A2069/A2229/A2233/A2232/A1876/A2014/A1895/A1983
Stylus Pen For Ipad,Stylus Pen,Stylus Pen For Drawing,Touch Pencil
Shenzhen Ruidian Technology CO., Ltd , https://www.wisonen.com