Analyzing the Burnout Scenarios of Crystal Oscillators in PCBA Assembly requires a distinction based on the internal structure and operational principles. For passive crystals, burnout situations are typically attributed to:
1. Improper Hand Soldering Operation
- High temperatures or prolonged heating during hand soldering can damage the internal wafer silver plating layer, resulting in poor resistance and a failure to initiate crystal vibration.
2. Excessive Excitation Power
- Inappropriate selection of excitation power, especially when changing the circuit input arbitrarily, can lead to increased temperature in the quartz wafer vibration area. This temperature rise destabilizes the frequency and, in severe cases, may cause irreparable deformation and permanent frequency deviation, leading to crystal burnout.
Excessive excitation power may also damage the conductive adhesive between the solid wafer and the base, resulting in internal circuit breakage and crystal vibration cessation.
In contrast, passive crystals used in circuit applications typically experience low applied voltages, making burnout rare. This issue is more prevalent in the misuse of active crystals, requiring careful consideration.
For active crystals, burnout scenarios are categorized as follows:
1. Incorrect Voltage Input Direction
- Misconnection of the voltage input, such as applying voltage to the ground pin instead of the designated voltage input pin (VCC), can lead to current flow and subsequent burnout.
2. Input Voltage Parameter Selection Error
- Incorrect selection of input voltage parameters, especially supplying a higher voltage than the crystal oscillator’s rated voltage, poses a significant risk of burnout.
A crucial reminder for active crystals is that they are susceptible to destruction only when subjected to an overloaded high-voltage power supply. Ensuring correct voltage connections and parameters is essential to prevent burnout incidents.
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