The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 09, 1984
Filed:
Feb. 01, 1983
Fairchild Camera & Instrument Corp., Mountain View, CA (US);
Abstract
Apparatus and method are described for rapid ball formation at the end of lead wire retained in the capillary wire holding tool of a ball bonding machine. A circuit is coupled between the cover gas shroud and lead wire for establishing controlled electrical discharge between the end of the bonding wire and the shroud, for melting and forming a ball. The circuit includes a DC power supply for delivering a positive polarity to the shroud and negative polarity to the lead wire for drawing a discharge of electrons from the end of the lead wire to the shroud. A capacitor is coupled in series with the DC power supply for receiving the electrical discharge. An impedance is also coupled in series for limiting the electrical discharge current. Charging of the capacitor limits and shapes the electrical arc discharge to a controlled pulse profile of short duration for rapid ball formation. An electronic gate is also used to control pulse duration. The rapid and controlled ball formation avoids necking or thinning of the lead wire which often occurs at the stem above the bonding ball.