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:
Jun. 10, 1986
Filed:
Jul. 25, 1983
Shane Harrah, Palo Alto, CA (US);
William Phy, Los Altos Hills, CA (US);
Fairchild Camera & Instrument Corp., Cupertino, CA (US);
Abstract
The present invention relates to a method and apparatus for forming a ball bond between a fine wire such as aluminum wire and a surface with the ball bond being approximately radially symmetric about a principal axis of a portion of the wire. The apparatus may include a plurality of electrodes radially spaced about the wire to define gaps between each electrode and the tip of the wire and a plurality of resistance elements. A voltage source may be connected to form a circuit consisting of plural electrically parallel legs, each of which includes the series combination of a resistance element, an electrode and an arc path between the electrode and the tip of the wire. A molten ball is formed at the end of the wire when arcs are essentially simultaneously produced between the electrodes and the tip of the wire. In a preferred embodiment, the resistances of the resistance elements are approximately equal. In addition, the plurality of electrodes are preferably symmetrically spaced about the wire to define gaps of nearly equal length between each electrode and the tip of the wire.