How to Solve the Problem of Crystal Oscillator Damage Caused by Ultrasonic Welding?

On the issue of ultrasonic welding leading to crystal oscillator damage, we mainly analyze the following two aspects：

1. Ultrasonic operation: please comply with the ultrasonic operation procedures

①Confirm the performance of the ultrasonic machine, such as ultrasonic welding head design is reasonable; ultrasonic machine in use when adjusting the parameters are in the best condition

②Do not work overtime

③Properly reduce the ultrasonic frequency

2. The product

①Product shell design should be reasonable

②Make the crystal oscillator position as far as possible from the edge of the circuit board

③Choose "over ultrasonic crystal oscillator" products, ultrasonic may cause a large number of ordinary crystal oscillators bad, which is related to the crystal manufacturing process.

In short, any one of the above conditions is not up to standard, it may lead to damage to the crystal oscillator after the ultrasonic vibration stopping problem, directly causing electronic products to function badly.

Attachment: ultrasonic welding knowledge

1. Ultrasonic welding principle

Ultrasonic welding uses high-frequency vibration waves transmitted to the surface of two objects to be welded, which, under pressure, cause the two surfaces to rub against each other and form a fusion between molecular layers. Ultrasonic welding is carried out by means of an ultrasonic generator that converts 50/60Hz current into 15, 20, 30 or 40 KHz electrical energy. The converted high-frequency electrical energy is converted again into mechanical motion of the same frequency by means of a transducer, which is then transmitted to the weld head by a set of variable amplitude rods that can vary the amplitude. The welding head transfers the received vibration energy to the joint of the part to be welded, where the vibration energy 

is converted into heat by means of friction, melting the area of the part to be welded.

2. Ultrasonic plastic welding principle

When ultrasonic waves are applied to the contact surface of thermoplastic plastics, high-frequency vibrations of several tens of thousands of times per second are generated, which reach a certain amplitude and transmit ultrasonic energy to the welding area through the upper welding parts. Due to the poor thermal conductivity of the plastic, it is not yet possible to distribute it in time and gather in the welding area, resulting in the rapid melting of 

the two plastic contact surfaces, which, together with a certain pressure, is made to fuse into one. When the ultrasonic waves stop working, let the pressure last for a few seconds, so that it solidifies and shapes, thus forming a solid molecular chain to achieve the purpose of welding, and the welding strength can be close to the strength of the raw material.

Advantages：

①Fast welding speed, high welding strength and good sealing

②Cost-effective alternative to traditional welding/bonding, clean and non-polluting without damaging the workpiece. Ultrasonic plastic welding depends on three factors: the amplitude of the transducer head, the pressure applied and the welding time, etc. The welding time and head pressure are adjustable, the amplitude is determined by the transducer and the variable amplitude rod. 

There is a suitable value for the interaction of these three quantities, when the energy exceeds the suitable value, the amount of plastic melting will be large and the weld will be easily deformed; if the energy is small, it will not be easy to weld firmly and the added pressure should not be too large. This optimum pressure is the product of the edge length of the welded part and the optimum pressure per 1mm of the edge.