METHODOLOGY TO MINIMIZE PROBLEMS ASSOCIATED WITH ULTRASONIC WELDING OF PRINTED CIRCUIT BOARD ASSEMBLIES

Ultrasonic welders deliver high frequency vibrations to bond and seal two or more materials into a unitized package. These welders require specially designed tips or horns to transfer ultrasonic vibrational energy that bonds the parts. Typical vibration frequencies are in the range of 20,000 or 40,000 hertz; the specific range of frequencies found to be the causation of damage to certain electronic components.

It has been reported that rejection rates of up to 10% per run can occur when ultrasonic welders are utilized to weld plastic housings' that surround PCBs*. In particular the input capacitor appears to be the most vulnerable component subject to ultrasonic damage. Further, the same problem arises when quartz clocks are welded resulting in resonant frequency changes to the crystal.

Damage is believed to be the result of high frequency oscillations transmitted to a particular component. In some cases certain frequencies, specifically near 40 KHz, have been incorporated to reduce rejection rates, but not by a significant degree.

Consequently, these results indicate that ultrasonic frequencies are not totally capable of insuring low rejection rates when utilizing ultrasonic welding equipment.

A unique solution to this problem has recently been employed to significantly reduce post weld rejection rates. This technology incorporates a vibration-less Infra-Red weld process that seamlessly joins plastics in a hermetic seal. Some of the advantages of this technique are listed below:

No vibration

Minimize weld rejection rates

Low operational costs (low amps)

Handle immediately after welding

Eliminate expensive horn and converter replacements

Ease of handling pre and post weld

The intrinsic worth and added performance of Infra-Red welding technology offers the user a quantum jump in cost savings, functionality and efficiency. TRINETICS GROUP, INC., located in Melbourne FL. is a leader in the engineering development in operational performance of IR welding technology.