Au-Ga-In Brazing Material

Abstract

A brazing material which can be melted at a suitable temperature at which damage is not given to a device inside a package upon sealing, and besides the brazing material is not remelted, e.g., upon mounting to a board, and which has a low temperature difference between a liquid and a solid. The brazing material is made of a Au—Ga—In ternary alloy, wherein weight concentrations of the elements lie within a region of a polygon with a point A (Au: 90%. Ga: 10%, In: 0%), a point B (Au: 70%, Ga: 30%, In: 0%), a point C (Au: 60%. Ga: 0%. In: 40%) and a point D (Au: 80%, Ga: 0%. In: 20%) as vertexes. excluding lines on which In and Ga become 0%, in a Au—Ga—In ternary phase diagram.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a brazing material and a sealing method using the brazing material. In particular, the present invention relates to a brazing material used for hermetically sealing a package for various electronic components. The present invention provides a brazing material which is not remelted, e.g., upon mounting to a board without giving damage to a device inside the package upon sealing and has suitable properties.[0003]2. Description of the Related Art[0004]Electronic components such as an SAW filter and a crystal oscillator used in various types of electronic equipment such as a cellphone are hermetically sealed in a package made of ceramics or the like in view of protecting an internal device. A brazing material for sealing the package has progressively been made lead-free in view of recent environmental protection. In this view, a Au—Sn brazing material (particularly, a Au-20 wt % Sn brazing m...

AI Technical Summary

Benefits of technology

[0016]The ternary phase diagram showing the composition of the material according to the present invention is shown in FIG. 1. The ternary alloy is applied in the present invention since the melting point of the ternary alloy can be adjusted more effectively than a binary Au alloy (Au—In, Au—Ga) by simultaneously adding two elements of Ga and In to Au. The melting point (the liquidus, the solidus) can be set within a suitable range by setting the added amount of Ga and In to the range within the region. The composition adjustment can also moderately reduce a temperature difference between the liquidus and the solidus. The brazing material of the composition range can be made suitable even in processability and hardness.

[0018]The ternary brazing material according to the present invention may contain at least one addition element of Sn, Ge, Zn, Sb, Si, Bi and Al. These addition elements are added in order to finely adjust the melting point of the brazing material and improve the wettability of the brazing material. The content of the addition element is preferably 0.001 to 3.0% by weight, more preferably 0.01 to 3.0% by weight, and still more preferably 0.1 to 3.0% by weight.

[0022]The brazing material according to the present invention is suitable for hermetically sealing the package member. Although the sealing package member has a base accommodating a cap (lid) serving as a lid body and a device, any of the cap and the base is preferably provided with the brazing material made of the alloy according to the present invention. When the brazing material is fixed to the package member, the brazing material is placed on the member, and the brazing material is melted and solidified in a heating atmosphere to be fused. Kovar (an Fe—Ni—Co alloy) and 42 alloy (an Fe—Ni alloy) are generally used as the material of the cap of the package member. Ceramic is used as the material of the base. When the brazing material is fused, a fusing surface is previously subjected to Ni plating and / or Au plating from the object of improving the wettability of the brazing material, or the like. The brazing material according to the present invention can also be fused to the package member previously provided with these plating layers.

[0024]As described above, the brazing material according to the present invention has suitable melting properties, and is suitable for sealing the package. The brazing material has the improved temperature difference between the liquidus and the solidus, and has excellent workability. The brazing material according to the present invention also has good processability, and can also be processed into a brazing material for a package requiring downsizing and slimming down.

Problems solved by technology

Although the Au—Sn brazing material has preferable properties upon the sealing operation of the package, the Au—Sn brazing material also has a problem.

The problem is caused when the sealed package is mounted to a board.

Since a temperature upon mounting is close to the melting point of the Au—Sn brazing material, the heat remelts the brazing material to cause peeling and leak of the sealed part of the package.

Another problem to be concerned about, other than the case where the package is mounted to the board, is that when the board is heated to collect damaged parts in repairing the electronic equipment, the heat may break the sealing of other non-damaged parts.

However, the Au—razing material tends to have an excessively high melting point.

The sealing performed in the high temperature atmosphere increases the thermal damage of a device inside the package, and may possibly damage the element.

However, ternary alloys such as the Au—Ge—Sn brazing material may cause a problem of a temperature difference between a liquidus and a solidus.

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