JPH0347579B2 - - Google Patents

Abstract

PURPOSE:To obtain an Al small-gage wire having excellent bonding properties by selecting the kinds and quantity of addition of elements to be added to Al having high purity. CONSTITUTION:0.5-2.0wt% Mg is added to Al having not less than 99.9% purity, and one kind or two kinds or more of elements of Pd, Pt, Rh, Ru, Os, Ir are further added by 0.01-1.0wt% in total. When the Al alloy is melted and casted, wire-drawn to form a small-gage wire having a 0.02-0.5mm.phi diameter and thermally treated (350 deg.C and 30min), and Al small-gage wire obtained has proper tensile strength and adhesive strength, and also has excellent corrosion resistance and uniform quality.

Description

[Detailed description of the invention]

The present invention relates to a 0.02 to 0.5 mmφ Al wire for wire bonding used to connect chip electrodes of semiconductor devices to substrates or lead frames. In general, wire for bonding requires a certain tensile strength to prevent breakage during wire drawing and bonding work, and also prevents high temperature softening during bonding to stabilize the ball shape, prevent neck breakage, and maintain a constant crush width. It is required to maintain adhesive strength (bonding strength) after bonding and bonding, and corrosion resistance is also an important condition when the wire is exposed to a corrosive atmosphere as in the case of resin molding. However, since high-purity Al is too soft to achieve the desired tensile strength, it has been considered to improve the mechanical strength by adding various elements to high-purity Al, but the types of added elements Depending on the amount added, the specified tensile strength may not be obtained, and even if tensile strength is obtained, it may be too hard and cause chip cracking, or the tensile strength and bonding strength may become uniform due to polarization of the added element. This results in variations in quality. The present invention was developed in view of the above circumstances, and it has been found from experimental results that it is possible to ensure proper tensile strength and bonding strength with excellent bonding properties, improve corrosion resistance, and improve quality by changing the type and amount of added elements. Al for bonding to uniformize
The Al wire of the present invention is
High purity Al (99.9% or more) contains 0.5 to 2.0 wt% Mg and platinum group elements (Pd, Pt, Rh,
The gist is that at least one element selected from Ru, Os, and Ir is contained in an amount of 0.001 to 0.3 wt%. The above-mentioned Al has a high purity of 99.9% or more, and magnesium (Mg) increases the tensile strength of Al. Platinum group elements (Pd, Pt, Rh, Ru, Os, Ir) are
Its addition increases the tensile strength of Al and is useful for improving corrosion resistance. One or more of the above platinum group elements may be added, but even if two or more are added, the content should be controlled.
The content should be 0.001-0.3wt%. If Mg is less than 0.5 wt% and one or more platinum group elements are less than 0.001 wt%, the desired tensile strength cannot be obtained, making wire drawing impossible and poor corrosion resistance. In particular, when platinum group elements are insufficient, the desired corrosion resistance cannot be obtained. Furthermore, if Mg exceeds 2.0wt% and platinum group elements exceed 0.3wt%, the chip becomes too hard and brittle, leading to chip cracking or uneven composition, resulting in variations in mechanical strength and poor quality. Unable to stabilize. Examples are shown below. Each sample was made by melting and casting an Al alloy and drawing it into an ultra-fine Al wire for bonding with a diameter of 0.03 mmφ. The added elements and their amounts added to each sample are as shown in the following table (1).As platinum group elements, Pd, Pt,
Rh, Ru, Os, and If were added. Sample No. 33 is a comparative product in which no platinum group element is added. In the present invention, the remainder contains unavoidable impurities.

【table】

[Table] Table (2) shows the results of measuring the mechanical properties and corrosion resistance of each of the above samples.

【table】

[Table] Samples Nos. 11 to 14 and 28 to 32 had bonding strengths that did not reach the required strength and had large polarization, and variations in bonding strength were observed even for samples of the same type. Note that the heat treatment was performed at 350°C for 30 minutes. In addition, corrosion resistance is high under high temperature and high humidity conditions (120℃, 2 atm,
The degree of corrosion under conditions of humidity of 90% or higher for 100 hours was classified into three ranks, and ranked as ×, 〇, and ◎ in descending order from the highest degree of corrosion to the lowest. As can be seen from Table (2) above, in the range of the products implementing the present invention (Samples Nos. 1 to 10 and 15 to 27), the hardness after heat treatment is in an appropriate state (25 to 50 Hv), and the tensile strength is It was confirmed that the strength was ensured, the required bonding strength (3 g or more) was ensured, and the corrosion resistance was excellent. Therefore, the product of the present invention does not break during wire drawing or bonding, prevents chip cracking, and maintains high quality and stable quality, making it suitable for ball bonding. Al wires with excellent bonding properties can be provided by either thermocompression bonding or ultrasonic bonding.

Claims (1)

[Claims] 1 High purity Al contains 0.5 to 2.0 wt% magnesium (Mg) and platinum group elements (Pd,
An Al wire for bonding semiconductor devices containing at least 0.001 to 0.3 wt% of - elements selected from Pt, Rh, Ru, Os, Ir).