How to solve the causes of crystal failure

Aug 21,2024
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Every product requires a lot of programs before completing the inspection. The circuit board is equipped with liquid crystal electronic products. During the inspection process, under pressure, alcohol and quartz crystals are prone to collide with the shell, and the vibrating chip is prone to collision, causing faults such as vibration or vibration stoppage when the crystal vibrates.?

Reason for crystal failure:

When sealing, the inside of the crystal requires vacuum nitrogen filling. If the sealing pressure is poor, the poorly sealed quartz crystal is called double leakage when alcohol is under pressure. When leaking, it will cause vibration to stop.

2. Due to the thin thickness of the chip itself, when the excitation power is too high, the internal quartz plate will be damaged, causing it to stop vibrating.

3. When the through-hole of the circuit board penetrates into the solder wire, it may cause the pin connection with the shell, or during the manufacturing process of the crystallizer, the solder pin point on the base may be connected to the shell. Single leakage will cause a short circuit, resulting in vibration stoppage.

(4) Quartz crystal oscillators generate mechanical and thermal stresses during shearing and welding, and high soldering temperatures and long durations can affect the crystal, leading to the formation of critical crystals that vibrate and even stop.

(5) Active loading will reduce the Q value (i.e. quality factor), leading to decreased stability of the crystal and instability due to the influence of surrounding active components.

(6) When the frequency drift of the 3225 chip oscillator exceeds the frequency offset range of the crystal, it cannot capture the center frequency of the crystal, resulting in the chip not oscillating.

Methods to solve crystal oscillator failure

To solve the problem of crystal oscillator malfunction, 1) According to technical requirements, conduct leak testing on quartz crystal components, check their sealing condition, promptly deal with defective products, and analyze the causes.

(2) The sealing process is to encapsulate the tuning resonant element in nitrogen protection to stabilize the electrical performance of the quartz resonator. This program should keep the feeding bin, pressure sealing chamber, and discharge clean. The sealing bin should be continuously pressurized with nitrogen, and attention should be paid to head wear and mold position during the sealing process. The voltage, pressure, and nitrogen flow rate should be normal, otherwise they should be dealt with in a timely manner. Quality standards: No scars, burrs, holes, bends, or oblique symmetry during stamping.

(3) Due to the fact that quartz crystals are passive components that work properly and are powered by IC drivers, when the excitation power is too low, the crystal is less likely to vibrate. When the excitation power is too high, it can cause excitation, breakage of the quartz plate, and cessation of vibration. Therefore, appropriate motivational forces should be provided. In addition, active loads consume a certain amount of power, thereby reducing the Q value of the crystal and decreasing its stability. The crystal is easily affected by surrounding active components and does not vibrate in an unstable state. Therefore, external power loads should be matched with appropriate power loads.

(4) Control the cutting and welding process to ensure the quality of insulation and bottom pins, with pins that are bright and uniform, without pits, deformations, cracks, scratches, stains, discoloration, and peeling. To prevent leakage, insulation gaskets can be added to the crystal.