D-Pak package transistors of the raised heat dispersion capacity have a copper alloy crystal mount for maintenance of low thermal resistance. Various technologies of SMT soldering are connected to intensive heating, danger bursting transistor structure, penetration of moisture inside of the package and degradation transistor's characteristics. Influence constructive and technology factors on stability of transistors to thermal loadings up to 400 0 are investigated.

Ultrasonic (US) soldering of electronic components, as an alternative to flux soldering, is environmentally friendly, improves the quality of soldered connections at the mounting elements after long-term storage, and allows the use of lead-free solders. Methods of US solder melt activation, lead-free solders in US soldering and glass-ceramic capacitor metallization processes have been investigated.

Parameters of infrared heating for soldering electronic components using surface mounting are investigated and optimized. The main advantages of IR heating are as follows: high rate, low lag effect, possibility to effectively change the temperature and time profile of heating, and the relative simplicity of the equipment.

Modeling and experimental research of diffusion processes during formation of soldered connections under the influence of energy of ultrasonic and electric fields were performed. It was found that the concentration of diffusion elements increased in the interface depth by 30-45%; owing to this, the durability of the connections with difficult-to-solder metals increased by a factor of 1.25-1.5.

The local introduction of ultrasonic vibrations parallel to the processed surface combined with IR heating in melts allows one to concentrate the activation energy in a small volume. This reduces the mechanical action on the processed surfaces, lowers the melt oxidation, and increases the durability of the soldered connections.