How to control and solve the problem of chip cracking during LED die bonding process?

 The single-electrode chip has very high requirements for die bonding in the packaging industry. For example, in the LED production process, the quality of die bonding affects the quality of the LED finished product. There are many factors that cause LED die bonding cracks. We only discuss the solutions to LED die bonding cracks from three aspects: materials, machines, and human factors.

　　1. The chip material itself is cracked

　　When the chip damage is greater than 1/5 of the width of a single side chip or the damage is at an oblique angle, the length of each single side is greater than 2/5 of the chip or the damage reaches the aluminum pad, such chips are unacceptable (this is one of the items in the chip inspection standard). The main reasons for the adverse phenomenon are:

　　1. Improper operation of chip manufacturers

　　2. The chip incoming material inspection was not carried out

　　3. Not selected during online operation

　　Solution:

　　1. Notify chip manufacturers to make improvements

　　2 Strengthen incoming material inspection and reject chips with too many damaged chips.

　　3. During the online Q inspection, the damaged chips should be picked out and replaced with good chips.

　　2. Improper use of LED die bonding machine

　　1. Improper machine suction parameters

　　The suction nozzle height and the height of the die bonding are directly controlled by the parameters in the machine computer. If the parameters are large, the suction height is small; if the parameters are small, the suction height is large. Whether the chip is damaged or not is directly affected by the suction height parameters of the machine. The main reasons for the bad phenomenon are: the machine parameters are large, the suction height is low, and the chip is subjected to excessive force, resulting in chip damage.

　　Solution:

　　Adjust the machine parameters, appropriately increase the height of the suction nozzle or the height of the bonding die. In the "SETUP" mode of the machine, in the "Bond head menu" in the first item "Pick Level" adjust the suction nozzle height, and then adjust the bonding die height in the second item "Bond Level".

　　2. The nozzle size does not match

　　Different sizes of chips require different nozzles for die bonding. If a large chip is used with a small nozzle, the chip cannot be sucked up and is prone to leakage; if a small chip is used with a large nozzle, the chip is easy to break. Therefore, choosing an appropriate nozzle is the premise for good chip bonding. The reason for the bad phenomenon is: the nozzle is too large and breaks the chip.

　　Solution: Choose the appropriate porcelain nozzle.

　　3. Cracks caused by improper human operation

　　A. Improper operation

　　Failure to follow the specified operation may result in chip damage. The main reasons for the adverse phenomenon are:

　　1. The materials were not held properly and fell to the ground.

　　2. Touch the chip when entering the oven

　　Solution: Hold the ingredients steady. Place the ingredients flat and gently into the oven without tilting or applying excessive force.

　　B. Heavy objects crushing

　　The chip is broken due to excessive external force. The main reasons for this phenomenon are:

　　1. The microscope fell onto the material, breaking the chip

　　2. Machine parts fall onto the material.

　　3. The iron plate presses the material

　　Solution:

　　1. Tighten the microscope screws

　　2. Check machine parts regularly to see if they are loose.

　　3. No objects such as iron plates can pass over the material.