EP0133118A2
Expired / Lapsed
EP
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Method and apparatus for forming ball bonds
Assignee: Fairchild Semiconductor Corp
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Filing: 1984-07-19
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Granted: —
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Expires: 2004-07-19
Abstract
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. Avoltagesource 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.
Inventors
- 👤 Shane Harrah
- 👤 William Phy
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 19:03
CPC Classifications
B; B23; B23K; B23K20/00; B23K20/002; B23K20/004; B23K20/005; B23K20/007; H; H10; H10W; H10W72/00; H10W72/01; H10W72/015; H10W72/01551; H10W72/071; H10W72/0711; H10W72/07141; H10W72/075; H10W72/07511; H10W72/07521; H10W72/07531; H10W72/07532; H10W72/07533; H10W72/07541; H10W72/50; H10W72/531; H10W72/536; H10W72/5363; H10W72/541; H10W72/5449; H10W72/551; H10W72/552; H10W72/5522; H10W72/5524; H10W72/59; H10W90/00; H10W90/701; H10W90/751; H10W90/756
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
128 words
An apparatus for forming a molten ball at a tip of a wire to permit ball bonding of the wire to a surface, comprising: electrode means adjacent the tip of the wire; and a voltage source for energizing the electrode means to produce an arc between the electrode means and the tip of the wire to form a molten ball in the tip of the wire; characterized in that said electrode means comprises a plurality of electrodes spaced about the tip of the wire to define gaps between each electrode and the tip of the wire; and said voltage source comprising means for essentially simultaneously producing an arc between each electrode and the tip of the wire to form a molten ball in the tip of the wire.
Claim 2
Independent Claim
128 words
An apparatus for forming a molten ball at a tip of a wire to permit ball bonding of the wire to a surface, comprising: electrode means adjacent the tip of the wire; and a voltage source for energizing the electrode means to produce an arc between the electrode means and the tip of the wire to form a molten ball in the tip of the wire; characterized in that said electrode means comprises a plurality of electrodes spaced about the tip of the wire to define gaps between each electrode and the tip of the wire; and said voltage source comprising means for essentially simultaneously producing an arc between each electrode and the tip of the wire to form a molten ball in the tip of the wire.
Claim 3
Dependent Claim
19 words
The apparatus according to Claim 1, characterized in that said plurality of electrodes are radially spaced about the wire.
Claim 4
Dependent Claim
29 words
The apparatus according to Claim 1 or 2 wherein said plurality of electrodes are positioned to define generally equidistant gaps between each electrode and the tip of the wire.
Claim 5
Dependent Claim
62 words
The apparatus according to Claim 1, 2 or 3 characterized by a plurality of resistance elements, and further characterized in that said voltage source is electrically connected to form a circuit consisting of plural, electrically parallel legs, each leg including the series combination of a resistance element, an electrode and an arc path between the electrode and the tip of the wire.
Claim 6
Dependent Claim
20 words
The apparatus according to Claim 4, characterized in that the resistances of said plurality of resistance elements are approximately equal.
Claim 7
Dependent Claim
21 words
The apparatus according to Claim 1, 2, 3, 4 or 5 characterized in that the voltage source comprises a capacitor bank.
Claim 8
Dependent Claim
68 words
The apparatus according to Claim 4, 5 or 6 characterized in that the voltage of the voltage source, the resistance of the resistance elements and the spacings of the electrodes are selected such that stable arcs are formed between all of the electrodes and the wire through a range of gap distances corresponding to the variations encountered in the positioning of the wire with respect to the electrodes.
Claim 9
Dependent Claim
33 words
The apparatus according to Claim 1, 2, 3, 4, 5, 6 or 7, characterized in that the plurality of electrodes lie approximately in a plane perpendicular to the principal axis of the wire.
Claim 10
Dependent Claim
41 words
The apparatus according to Claim 1, 2, 3, 4, 5, 6, 7 or 8, characterized in that the plurality of electrodes are four in number and are symmetrically positioned in a radial array about the wire at intervals of approximately 90°.
Claim 11
Dependent Claim
30 words
The apparatus according to Claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, characterized by means for providing a reducing atmosphere about the electrodes and the wire tip.
Claim 12
Dependent Claim
42 words
The apparatus according to Claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, characterized by means for providing a reducing atmosphere about the electrodes and the wire tip which includes a mixture of a reducing gas and an inert gas.
Claim 13
Dependent Claim
29 words
The apparatus according to Claim 11, characterized in that the reducing gas is hydrogen and the inert gas includes at least one of the group of argon and helium.
Claim 14
Dependent Claim
25 words
The apparatus according to Claim 12, characterized by means for flowing the gas mixture along the principal axis of the wire in a laminar fashion.
Claim 15
Independent Claim
17 words
The apparatus according to any of Claims 1 to 13 characterized in that the wire is aluminum.
Claim 16
Independent Claim
127 words
A method for forming a ball bond between a wire and a surface including, the steps of: placing electrode means adjacent a tip of the wire; applying a voltage to the electrode means to produce an arc between the electrode means and the wire to form a ball at the tip of the wire; and placing the ball and the surface in contact with one another; characterized by the step of positioning a plurality of electrodes about the tip of the wire to define gaps between each electrode and the tip of the wire; providing a voltage source to each of the plurality of electrodes; and essentially simultaneously producing an arc between the wire and each electrode to form the ball at the tip of the wire.
Claim 17
Independent Claim
127 words
A method for forming a ball bond between a wire and a surface including, the steps of: placing electrode means adjacent a tip of the wire; applying a voltage to the electrode means to produce an arc between the electrode means and the wire to form a ball at the tip of the wire; and placing the ball and the surface in contact with one another; characterized by the step of positioning a plurality of electrodes about the tip of the wire to define gaps between each electrode and the tip of the wire; providing a voltage source to each of the plurality of electrodes; and essentially simultaneously producing an arc between the wire and each electrode to form the ball at the tip of the wire.
Claim 18
Dependent Claim
26 words
The method according to Claim 15, characterized in that said plurality of electrodes are positioned relative to the wire such that said gaps are substantially equal.
Claim 19
Dependent Claim
26 words
The method according to Claim 15 or 16, characterized in that said plurality of electrodes are positioned radially about the wire and symmetric with respect thereto.
Claim 20
Dependent Claim
20 words
The method according to Claim 15, 16 or 17 characterized in that said plurality of electrodes are four in number.
Claim 21
Dependent Claim
28 words
The method according to Claim 15, 16, 17 or 18, characterized by the step of providing a reducing atmosphere about the electrodes and the tip of the wire.
Claim 22
Dependent Claim
29 words
The method according to Claim 19, characterized in that said providing step is practiced by flowing selected gas along the principal axis of the wire in a laminar fashion.
References Cited (Backward Citations)
No citation records indexed.
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