Palladium-coated copper wire for ball bonding

Abstract

The invention provides a palladium-coated copper wire for ball bonding, wherein the copper wire is good in deconvolution performance and stable molten balls can be formed. Meanwhile, the problem in the prior art that molten balls formed through a welding wire obtained during the mass production through FAB are not stable can be solved. The palladium-coated copper wire for ball bonding is characterized in that the wire diameter of the copper wire is 10-25 mum. A palladium-coated layer is formed on a core material made of copper or copper alloy. The palladium-coated layer contains a pure layer only contains palladium. An exudation layer made of the copper of the core material is formed on the palladium-coated layer. In addition, the invention provides a palladium-coated copper wire for ball bonding. The copper wire is characterized in that the wire diameter of the copper wire is 10-25 mum, and a palladium-coated coating layer and a gold surface layer are formed on a core material made of copper or copper alloy. A copper exudation layer is formed on the gold surface layer. Meanwhile, the palladium-coated coating layer contains a pure layer only contains palladium.

Description

technical field [0001] The present invention relates to a palladium (Pd)-coated copper wire for ball bonding that is suitable for connecting IC chip electrodes used in semiconductor devices to substrates such as external leads. In particular, it relates to a copper wire that can be obtained even if it is an extremely thin wire of 15 μm or less. Copper-clad wire for stable molten balls. Background technique [0002] In general, a method called ball bonding is used for the first bonding of the copper-coated wire to the electrode, and a method called ball bonding is used for the second bonding of the copper-coated wire to the wiring on the circuit wiring board for semiconductors. Way of wedge joint. In the above-mentioned first joining, the tip of the coated copper wire is melted by applying arc heat input to the tip of the coated copper wire by the electronic flame extinguishing (EFO) method, and the molten material is solidified by using surface tension, and the tip of the w...

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Problems solved by technology

[0010] However, even a copper wire covered with a skin layer such as gold (Au) cannot obtain a stable molten ball like a pure palladium (Pd)-coated copper wire.

That is, even if the thickness of the coating layer is "the skin layer of 5 nm or less (Japanese Patent Application Laid-Open No. 2010-225722 (Patent Document 3 described later))", or "the coating layer is 0.001 to 0.02 times the wire diameter Thick palladium (Pd) cladding layer, ... the uppermost cladding layer with a theoretical final film thickness of 1 to 7 nm ... (Japanese Patent Application Laid-Open No. 2012-39079 (Patent Document 1 to be described later))", The shape of the molten ball at the time of the first bonding by FAB is also unstable, and as a result, the bonding strength at the time of the first bonding is unstable

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