A kind of preparation method of bonding gold-silver alloy

Abstract

The invention relates to a preparation method of a bonding gold-silver alloy and belongs to the technical field of bonding wire machining process. The bonding gold-silver alloy wire is composed of the following metal materials in a weight ratio: 20-30% of silver, 5-1000ppm of palladium, calcium, beryllium and cerium and the balance of gold; the preparation method comprises the following steps: 1) preparing materials; 2) smelting an alloy ingot; 3) cast-drawing an alloy rod; 4) drawing a wire; 5) performing annealing; 6) performing wiring; and 7) performing packaging. The preparation method of the bonding gold-silver alloy provided by the invention is reasonable and standard in process design and simple to operate. The produced bonding alloy gold-silver alloy wire is good in electric conductivity and stable in chemical property, has good resistance to oxidation, flowability and plasticity, has a relatively high breaking force and relatively good elongation, is moderate in price, and can fully meet the demand of an LED illumination technology in a semiconductor encapsulation industry on performance of the bonding alloy gold-silver alloy wire.

Description

technical field [0001] The invention relates to a method for preparing a bonding gold-silver alloy, and belongs to the technical field of bonding wire processing technology. Background technique [0002] Bonding wire is a fine metal wire inner lead for electrical connection between the input / output bonding point of the chip circuit and the inner contact point of the lead frame when semiconductor devices and integrated circuits are assembled. As a bonding inner lead, the bonding wire should have the following properties: high electrical conductivity, strong electrical conductivity, strong bonding with conductor materials, stable chemical properties, no harmful intermetallic compounds, good plasticity, easy welding, and It can maintain a certain shape and has a specified tensile strength and elongation. The bonding wires currently in use mainly include gold wires, aluminum-silicon wires, copper wires, and alloy wires, among which gold wires are widely used in IC inner leads b...

AI Technical Summary

Problems solved by technology

[0003] 1. Au2Al intermetallic compounds are prone to produce Kirkendall Void during bonding, which will cause cavities at the bonding place, sharply increase the resistance, destroy the ohmic connection of the integrated circuit, severely damage the conductivity or generate cracks, and easily cause device soldering here. The point is disengaged and fails;

[0004] 2. The heat resistance of gold wire is poor. During ball welding, the gold wire near the solder ball will form a recrystallized structure due to heating. If the gold wire is too hard, the ball neck will bend; when the solder ball is heated, the gold wire grains will become coarser. Will cause the ball neck to break;

[0005] 3. Gold wire is also easy to cause collapse and tailing, which seriously affects the quality of bonding;

[0006] 4. The price of gold wire is expensive, which has exceeded 360 yuan / gram, resulting in high packaging costs. At present, the biggest challenge in the semiconductor industry is how to control and reduce costs

[0017] 5. The shortcomings and technical differences of the current bonded gold-silver alloy wire

However, if this alloy wire is exposed to high humidity for a long time, it will oxidize

[0019] 2) Although gold and silver elements can dissolve in any composition, if you want to smelt to obtain alloy ingots with uniform composition, you need to go through multiple smelting to obtain

[0020] 3) By adding 5% Pd to the alloy, the interfacial corrosion problem in high humidity environment can be solved, but it will undoubtedly increase the cost

It is also reported that gold plating can be done directly on the basis of bonding silver wire or gold plating on the basis of alloy wire, which involves the problem of electroplating process, which undoubtedly increases the investment in equipment and the problem of process specification.