Crystal oscillator can not afford the reasons
First, the loss of the crystal oscillator reason;
1. In the leak detection process, the alcohol is in a pressurized environment, prone to crystal shell hit phenomenon that vibration chip easily collide with the housing, thereby appetite or stop vibration likely to occur when the crystal oscillator;
2. In the pinch seal, crystal internal requirements evacuated with nitrogen, adverse event of pressure seal, namely sealing when the crystal is not good, in alcohol pressurized conditions, the performance of the leak, called double drain, It will lead to stop vibration;
3. Since the thickness of the chip itself is thin, when the pumping power is too large, it will make the internal quartz chip damage cause to stop vibration;
4. active load will reduce the Q value (ie quality factor), so that the stability of the crystals decreases, susceptible to the surrounding active components influence in an unstable state, appetite phenomenon occurs when vibration;
5. Since the crystals shear pin and the solder when prone to mechanical and thermal stresses, and solder temperature is too high and too long will affect the role of the crystal, the crystal is likely to lead to a critical state, as well as vibration phenomenon occurs when weak, even stop vibration;
6. When the solder, when the solder wire through the hole circuit board to percolate through, resulting in a connection pin with the housing, or crystals in the manufacturing process, solder joints and the housing on the base of the pin is connected to a single occurrence drain, can cause a short circuit, causing stop vibration;
Crystal not afford to vibration causes and troubleshooting
Cause Analysis:
(1) PCB board faulty wiring;
(2) single-chip quality problems;
(3) crystal quality problems;
(4) or matching capacitance load capacitance crystal capacitor mismatch or quality problems;
(5) PCB board damp, resulting in an impedance mismatch and not vibrating;
(6) crystal oscillator circuit traces too long;
Between (7) feet crystal alignment;
(8) the impact of the external circuit.
solution:
(1) preclude the possibility of circuit errors, so you can use the appropriate type microcontroller recommended circuit for comparison.
(2) exclude the possibility of adverse external components, as nothing more than a peripheral part of resistors, capacitors, you can easily identify whether the yield.
(3) exclude the possibility of the crystal oscillator products to stop, because you will not only try twelve crystal.
(4) Try to change the crystal across the capacitor, also Xu Jingzhen able to start-up, the size of the capacitor, please refer to the crystal instructions.
(5) When the PCB routing traces oscillator circuit should be as short as possible and as close to the IC, to eliminate traces between crystal feet.
