Bonding Process for NTC Thermistor
Step 1: Expanding crystal. The expansion machine is used to expand the entire LED wafer film evenly provided by the manufacturer, so that the LED crystal grains that are closely arranged on the surface of the film are pulled apart, which facilitates thorn crystal.
Step 2: Adhesive. The expanded crystal expansion ring is placed on the surface of the back-glued machine where the silver paste layer has been scraped, and the silver paste is backed. Point silver paste. Suitable for bulk LED chips. The appropriate amount of silver pulp is used on PCB printed circuit board.
Step 3: Put the silver slurry into the stinger frame, and the LED chip will be spliced on PCB printed circuit board by the operator under the microscope.
Step 4: Place the PCB with the spinel crystal into a thermocycling oven and stand for a period of time at constant temperature. After the silver paste is cured, remove it (do not leave it for a long time; otherwise, the LED chip coating will bake yellow, oxidize, make difficulties to the bonding). If there is a LED chip bonding, the above steps are needed; if there is only an IC chip bonding, the above steps are cancelled.
Step 5: Stick the chip. Use the glue machine in the IC position of PCB printed circuit board to the right amount of red glue (or black glue), then use antistatic equipment (vacuum pen) to put the IC die chip correctly on the red glue or black glue.
Step 6: Drying. Put the naked film in the hot circulation oven and place it on the large plane heating plate for a period of time, or it can be cured naturally (for a long time).
Step 7: Bonding (threading). An aluminum wire bonder was used to bridge the wafer (LED die or IC chip) with the corresponding pad aluminum wire on the PCB, which is the internal lead welding of COB.
Step 8: Pre-test. Use the special detection tool (the COB has different equipment according to different USES, the simple is the high precise density voltage stabilized power supply) to test the COB board, and the unqualified board will be repaired again.
Step 9: Dispensing. The glue dispensing machine will be used to place the suitable amount of AB glue on the LED grain. IC will be encapsulated with black glue, and then it will be packaged according to the customer's requirements.
Step 10: Curing. Put the sealed PCB printed circuit board into a thermocycling oven and keep it at a constant temperature. Different drying time can be set according to the requirements.
Step 11: Post test. The sealed PCB printed circuit board can be used for electrical performance testing with special testing tools to distinguish between good and bad.