What are the causes of leakage current in small LED butterfly lamp beads?

Release Date:

2020-11-18

　　 Small butterfly LED light beads Leakage current is a common issue that many people encounter. But why does leakage occur? In fact, there are several possible causes for leakage in small butterfly LED chips. Some arise during the testing phase after the chips have been encapsulated; others develop after prolonged storage; still others result from aging; and some are caused by improper soldering. Below, we will examine these various causes of leakage in detail.

 

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　　1. Stress causes leakage in small butterfly LED beads.

　　Stress is induced by the thermal expansion and contraction of materials. Since the materials used in LED chips differ, their coefficients of thermal expansion also vary. During repeated temperature cycling, the materials cannot fully return to their original state at the point of initial contact, resulting in the development of residual stress between them.

　　This stress is not necessarily harmful. Significant residual stress only arises when the thermal expansion coefficients differ substantially and the process conditions are inappropriate. Such severe stress can crush the chip, causing it to fracture, leading to leakage current, cracking in certain areas, loss of light emission, or complete open-circuit failure. When the stress exceeds a critical threshold, serious consequences may ensue.

　　The side surfaces of the small butterfly LED chip feature dangling bonds. Stress induces minute displacements of surface atoms, leading to a greater degree of electric-field imbalance at these dangling bonds. This imbalance alters the energy-level structure at the p–n junction at the chip’s end face, resulting in leakage current.

　　2. Improper use can cause leakage in the small butterfly LED beads.

　　This situation is rare. Applying a high reverse voltage to an LED chip can damage the PN junction and cause leakage.

　　3. Improper processing leads to chip cracking.

　　 Small butterfly LED light beads An uneven chip bottom or voids beneath the solder pads can damage the chip and lead to leakage or failure during wiring. Improper adjustment of the wire bonder can also damage the chip, resulting in leakage or failure.

　　4. Electrostatic Issues

　　Electrostatic issues should also not be overlooked. Electrostatic discharge requires a conductive path; it is not the case that static itself directly causes damage. For small butterfly LED chips, if only a minor leakage current exists and a conductive path is present, accidental electrostatic damage may be considered. However, if such occurrences are frequent, they are more likely due to chip contamination or mechanical stress.

　　5. The silver paste height is too high, leading to partial soldering and subsequent leakage.

　　In the LED chip packaging industry, excessive silver paste and misaligned wire bonding that lead to leakage current are well-known, common issues.

　　6. Chip contamination leads to leakage

　　Leakage caused by chip contamination is a concern: Small butterfly LED light beads It is extremely small, and even dust can easily obscure it. Most importantly, dust, water vapor, and various impurity ions tend to adhere to the chip surface. These contaminants can penetrate the interior of the LED die on the surface and further diffuse into the die, thereby degrading its performance. For instance, copper ions and sodium ions readily diffuse into semiconductor materials, and even trace amounts can significantly impair the performance of semiconductor devices.

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