SU585939A1 - Ultrasonic microwelding method - Google Patents

Description

(54) METHOD OF ULTRASONIC MICROSWARK

tact with active centers for the seizure of metals.

It was established experimentally that an acoustic emission signal occurs in a very short time interval, for example, for aluminum, about 0.03 microseconds, and the spectrum lies in the kilohertz range. Then the second bandpass filter | p from the noise frequency spectrum cuts the frequency spectrum of the hypersonic range, for example, 1-3 kHz. This makes it possible to reduce the force effect on the joining elements, sharply accelerate the processes of mutual diffusion, dissolution of oxide films and the formation of a monolithic compound. This causes a sharp appearance of the phonon-phonon and phonon-electron interaction of the connected materials, which affects the quality of micro welding.

All this contributes to reducing the time of micro-welding to 0.04-0.1 sec, since the kilohertz (ultrasonic) region has a prevailing effect, its influence on the process of plastic deformation and the creation of physical contact, and the megahertz or gehagertz (hypersonic) region - to the setting of , the process of diffusion and the removal of internal stresses in the joint zone. The petals of perforated aluminum tape were welded using the described method with a contact pad made of an aluminum film of a thickness different from 1.2 µm on the chip of the integrated circuit without oxide passivation, and the following joint quality characteristics were obtained: the bond strength was 12-14 g; coefficient of variation for breakage; electrical contact resistance 0.5-1.2 ohm; The reproducibility of the contact resistance is 6-8%.

With the passivation of the integral crystal

about

Schemes with a SiO2 film of thickness 760A obtained the following quality indicators of the compounds: the strength of the compound is 7-11 g; coefficient of variation for the precipice 9-14%; contact electrical resistance of 2–5 ohms, the coefficient of reproducibility of contact resistance of 9–13%.

At the same time, the welding time was 0.22 sec.

Studies have shown that when connecting wire leads made of aluminum with a diameter of 30 µm with thin-film aluminum contacts 0.8 m thick on silica, the strength of the compound increases 1.2-1.3 times, the electrical resistance of the transition layer decreases by 1.9-2 , 1 time, and the reproducibility of the quality of compounds both in terms of transitional electrical resistance and strength increases to 3 times.

Distinctive feature of efficiency

This method is that there is

5 ability to make quality

welding through thin passivating dieleko

tric films up to 1000-ZOOOA. This is especially effective since it eliminates

0 an awkward technological step of removing passivating oxide films on the contact pads, which shortens the service life of the joint, as the occurrence of embrittlement is observed over time

5 due to corrosion.

Claims (2)

1. The method of ultrasonic micro-welding, P | ri which on the welded parts are served 0 ultrasonic vibrations of the frequency spectrum, characterized in that, in order to increase the quality of welded joints, in the initial period of the process when creating physical contact on the welded products 5, oscillations of the frequency spectrum of the ultrasonic range are applied, and then vibrations of the frequency spectrum of the hypersonic range are applied. 2. A method according to claim 1, characterized in that the frequency spectrum of ultrasonic vibrations Range 0 is chosen corresponding to the acoustic emission spectrum of the parts to be welded. Sources of information sprined in consideration during the examination 1. USSR author's certificate No. 502728, cl. 23K 19/04, 1974.