How to weld the crystal oscillator and what factors can cause the crystal oscillator damage?

What factors can cause crystal vibration damage?

There is a falling phenomenon in the production process, which means that only the crystal oscillator causes too much impact from the outside world, because the crystal oscillator chip is relatively thin and needs to be handled lightly.

When the crystal vibration is welded to the circuit board, the welding temperature may be too high, resulting in poor crystal vibration;

During the welding process, virtual welding is generated, that is, false welding, so that the crystal vibration is not electrified;

After the crystal vibration welding, the solder is connected to the line, resulting in short circuit phenomenon;

In the leak detection process, that is, under the environment of alcohol pressure, the quartz crystal resonator is easy to produce the phenomenon of shell collision, that is, the chip and the shell are easy to collide during vibration, so that the crystal is easy to lose or stop vibration during vibration;

During the compression sealing, the internal crystal is required to be vacuumed and filled with nitrogen. If the compression sealing is poor, that is, when the seal of the crystal is not good, under the condition of alcohol compression, it is manifested as air leakage, called double leakage, which will also lead to vibration stop;

Because the thickness of the chip itself is very thin, when the excitation power is too large, the internal quartz chip will be damaged, resulting in vibration stop;

Functional load will reduce the Q value (that is, the quality factor), so that the stability of the crystal is reduced, easy to be affected by the surrounding active components, in an unstable state, there is a phenomenon of stagnation when the vibration;

Because the crystal is easy to produce mechanical stress and thermal stress when cutting the foot and soldering, and the solder temperature is too high and the action time is too long will affect the crystal, which is easy to lead to the crystal in a critical state, and even the phenomenon of sluggish when the vibration occurs, and even the vibration stops;

When soldering, when the tin wire permeates through the hole on the circuit board, resulting in the heel housing connected to a piece, or during the crystal manufacturing process, the tin point of the pin on the base and the housing are connected to a single leak, which will cause a short circuit, resulting in vibration stop;

When the crystal frequency frequency drift, and beyond the quartz crystal vibration deviation range too much, so that the central frequency of the crystal can not be captured, resulting in chip vibration;

What do you need to pay attention to welding crystal vibration?

First of all, the temperature of the solder should not be too high, and the soldering time should not be too long, to prevent the crystal from internal change and instability. When the crystal shell needs to be grounded, it should be ensured that the shell and the pin are not accidentally connected, resulting in short circuit. This causes the crystal to fail to vibrate. Ensure that the solder points of the two pins are not connected, otherwise it will also cause the crystal to stop vibrating. For the crystal vibration that needs to be clipped, attention should be paid to the effect of mechanical stress. After soldering, it is necessary to clean so that the insulation resistance does not meet the requirements.

We know that the quartz crystal vibration welding method is related to his package, and the plug-in and the patch are two different welding methods. The chip vibration can be divided into manual welding and automatic welding.

The plug-in crystal oscillator welding is not very complicated. First, the crystal oscillator is placed on the circuit board with tweezers and the solder is melted with a heat gun so that it can be relatively simple;

Manual welding of chip crystal oscillator is relatively complicated.1. First, add an appropriate amount of solder to the chisel-shaped (flat shovel shaped) or knife-edge soldering iron tip, apply a small amount of flux with a fine brush dipped in flux or a welding aid pen on both ends of the pad, and plate the pad with solder; Hold the chip crystal oscillator with tweezers in one hand, and place it on the corresponding pad in the center, and do not move after alignment; With the other hand, pick up the soldering iron and heat one of the pads for about 2 seconds, then remove the iron; Then heat the other pad in the same way for about 2 seconds.

Special reminder: During the welding process, pay attention to keep the chip crystal oscillator close to the welding pad, and avoid the crystal oscillator end warping or welding distortion. If the solder on the pad is insufficient, you can take the soldering iron in one hand and the soldering wire in the other hand to repair welding, and the time is about 1 second.

First, appropriate amount of solder should be plated on the pad, hot air q1an9 should use a small nozzle, the temperature should be adjusted to 200℃ ~ 300℃, and the wind speed should be adjusted to 1 ~ 2 gear. When the temperature and wind speed are stable, hold the components with tweezers with one hand and place them on the welding position, pay attention to putting them correctly. With the other hand, hold hot air q1an9, keep the nozzle perpendicular to the component to be removed, 1cm ~ 3cm away, heat evenly, and remove hot air q1an9 after the solder around the chip crystal oscillator melts, and remove the tweezers after the solder cools.

In order to save money, many factories will use automatic SMT machine for automatic mounting. When welding, we should pay attention to several problems. If it is welding table crystal, it is recommended to use automatic SMT machine as far as possible, because the chip of table crystal quartz crystal vibration is relatively thin and the volume is relatively small. Under normal circumstances, the temperature of the soldering iron head is controlled at about 300℃, and the hot air gun is controlled at 200℃ ~ 400℃. 2, welding is not allowed to directly heat the chip crystal vibration pin above the heel, so as not to damage the internal capacitance of the crystal vibration; 3, need to use ∮0.3mm ~ ∮0.5mm solder wire; The soldering iron head is always smooth, no hooks, no thorns; The soldering iron head shall not touch the welding pad, do not repeatedly heat in a welding pad for a long time, and the working temperature of the conventional crystal oscillator is generally -40 - +85℃. Long-term heating of the pad may exceed the operating temperature range of the crystal oscillator, resulting in reduced life or even damage to the quartz crystal oscillator. In order to avoid damage to the resonator, please pay more attention to the major customers during the welding process to avoid unstable product performance.