The Effect of Electrostatic Discharge on BD139 transistor Reliability

Title: The Effect of Electrostatic Discharge on BD139 Transistor Reliability

1. Understanding the Fault Cause:

Electrostatic discharge (ESD) can severely impact the reliability of electronic components like the BD139 transistor. ESD is the sudden flow of electricity between two electrically charged objects, typically caused by contact between materials that have different electrical potentials. In the case of the BD139 transistor, which is a commonly used NPN power transistor, ESD can damage its delicate internal structures, leading to malfunction or complete failure.

What Happens During ESD? When a transistor like the BD139 is subjected to electrostatic discharge, the energy from the discharge can create a high voltage spike. This spike can exceed the maximum voltage tolerance of the transistor's junctions, causing:

Breakdown of the junctions: The internal PN junctions of the transistor can be damaged. Thermal damage: The sudden surge of current can generate excessive heat, leading to the destruction of the transistor’s materials. Permanent component failure: If the damage is severe enough, the transistor may stop functioning entirely or exhibit unpredictable behavior. 2. Fault Characteristics:

Transistors exposed to ESD may show signs of the following failures:

Failure to switch on/off properly: The transistor may no longer control the current flow as intended. Erratic behavior: The transistor may exhibit fluctuating or unstable performance. Complete failure: In extreme cases, the transistor may fail completely and become shorted or open. 3. Root Cause of the Failure:

The root cause of BD139 transistor failure due to ESD is primarily the lack of protection from electrostatic discharge. Other contributing factors may include:

Improper handling: If the transistor is handled without anti-static precautions, it becomes vulnerable to ESD damage. Inadequate packaging: If the transistor is not properly packaged in anti-static bags or materials, exposure to static charge during shipping or storage can damage it. Environmental factors: Working in areas with high static electricity (e.g., dry environments) without proper grounding or ESD-safe equipment can increase the risk. 4. How to Solve This Issue: Step 1: Implement Proper Handling Procedures

To prevent ESD-related failures, always follow these steps during handling:

Wear anti-static wristbands: Always use a grounded wrist strap when handling sensitive electronic components like the BD139 transistor. Work in an ESD-safe environment: Use ESD-safe mats, grounded surfaces, and ensure that your working area is well-equipped with anti-static devices. Use anti-static bags: Store and transport transistors in anti-static bags to avoid exposure to static charges. Step 2: Use ESD Protection Components

Add ESD protection components to your circuit design:

ESD diodes: Place ESD protection diodes across the transistor’s terminals to absorb excess voltage and prevent spikes from reaching the transistor. TVS (Transient Voltage Suppression) diodes: These can be used to clamp high-voltage transients and prevent them from damaging sensitive components like the BD139. Step 3: Upgrade Transistor Specifications

Consider using transistors that are specifically rated for higher ESD resistance if your application is prone to static electricity exposure. Some transistors are designed to withstand higher levels of ESD without failure.

Step 4: Ensure Proper Storage Store transistors in ESD-safe containers when not in use. Control the humidity in storage areas, as higher humidity can reduce the chances of electrostatic charge buildup. Step 5: Regular Testing and Inspection Test transistors before use: Always check for damage or malfunction before incorporating the BD139 transistor into your design. Inspect for physical damage: Visible cracks or discoloration on the transistor can indicate prior ESD-related damage, even if it hasn’t completely failed. 5. Conclusion:

ESD damage is a significant concern for the BD139 transistor’s reliability. By understanding the causes of this failure and implementing appropriate preventative measures—such as proper handling, using protective components, and working in an ESD-safe environment—you can significantly reduce the risk of ESD damage. Adopting these best practices will enhance the longevity and reliability of your BD139 transistors, ensuring their proper function in your circuits.