JPH03264187A - Powder sintered preform brazing material - Google Patents

Abstract

PURPOSE:To obtain a brazed object having a stable degree of joining by forming the above preform brazing material to the shape approximate to the shape of the joining area of a base material and to the numerical density of a specific range. CONSTITUTION:The powder sintered preform brazing material is formed to the shape approximate to the shape of the joining area of the base material and to the numerical density ranging 40 to 85%. For example, powder of 45% Ag, 30% Cu and 25% In is formed as this brazing material by an atomization method and after the powder is sieved to 50 to 100mum, the powder is previously packed into a round plate-shaped hollow groove of 3.00mm outside diameter and 0.3mm depth provided on the plate material made of carbon and is heated and sintered in hydrogen for 60 minutes at 550 deg.C in an electric furnace, by which many pieces of the round plate-shaped preform brazing materials having 2.5mm outside diameter and 0.16mm thickness are produced. The defective products are drastically decreased in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a preform brazing filler metal, and more particularly to a brazing filler metal used for brazing electrical contacts and the like.

(Prior Art and Issues) Conventionally, there has been a problem in that brazing does not provide sufficient stable bonding strength due to the generation of voids.

For example, when brazing a rivet and a disc-shaped contact as base materials, when a brazing material is sandwiched between the rivet head and the disc-shaped contact and heated and melted to join, the molten brazing material covers the entire joint surface. Since it flows into the outer periphery of the joint surface before wetting, there is a problem that the gas or air present in the gap between the rivet head and the disc-shaped contact becomes trapped and forms lipoids.
Eliminating this problem was a difficult problem.

For this reason, brazing is sometimes carried out using pressure, but this method has not yet been able to provide sufficient bonding strength because the trapped gas is difficult to escape. Therefore, when used as an electrical contact, when the contact wears out and becomes thin, there is a serious problem in that the contact part peels off or rolls up, causing bridging or welding.

(Object of the Invention) The present invention was made to solve the above problems, and provides a preform brazing material that can provide stable bonding strength.

(Structure of the Invention) The brazing material of the present invention for solving the above-mentioned problems is characterized by having a shape similar to the bonding area of the base metal and having a density in the range of 40 to 85%.

(Function) The preform brazing material of the present invention configured as described above is a porous brazing material made of sintered powder and having a density of 40 to 85% in a predetermined shape that approximates the bonding area. In brazing, the points where the solder wets the bonding surface of the base metal are sometimes dispersed over multiple points as shown in Figure 4, and the conventional problem is that the unwetted surface is concentrated in one place on the solder surface. It has the advantage that no fatal defects occur.

Of course, since the brazing material of the present invention is porous, gas and air exist in the pores, but during brazing, gas and air are heated and gradually released through the gaps in the continuous ventilation holes until they melt. It will not remain.

Further, the remaining gas is also finely dispersed, being within a range of only a few percent of the volume of the brazing filler metal, and does not lead to variations in bonding strength. When conventional plate materials are used, it is not uncommon for the area of voids gathered in one place to reach 40% of the brazing area, depending on the brazing conditions, which significantly reduces the reliability of brazing. It was causing this. If the density is less than 40%, the degree of sintering is poor and the sintered body becomes brittle, leading to problems such as chipping when placing the brazing material between the contact materials that are the base materials, or when transporting and handling the brazing material. In addition, if it is 85% or more, there are too few internal pores and continuous ventilation holes are lost, making it difficult for gas to escape and making it necessary to apply strong pressure when making a sintered body. This is because the equipment such as a press and the process become complicated, which has the disadvantage of impairing economic efficiency.

(Example) Examples and conventional examples will be described below.

First, as Example 1, Ag45%, Cu30%, In25
% powder by the atomization method, sieved to 50-100 μm, and then prepared in advance on a carbon plate with an outer diameter of 3.0 mm.
The powder was filled into a round plate-shaped groove with a depth of 0.3 mm, and heated and sintered in an electric furnace at 550°C for 60 minutes in hydrogen to give an outer diameter of 2.
100 circular preform brazing filler metals each having a diameter of 5 mm and a thickness of 0.16+ nm were obtained. Next, as Example 2, AuIn
27% powder was made using the atomization method, and the size was 50~1OOμm.
After sieving, the outer diameter of 3.0
Powder is filled into a circular groove with a depth of 0.35 mm and a depth of 0.35 mm.
The mixture was heated and sintered in hydrogen at 300° C. for 160 minutes in an electric furnace to obtain 100 round preform brazing filler metals each having an outer diameter of 2.6 mm and a thickness of 0.22 mm.

The densities of the preform brazing materials obtained in Example 1 and Example 2 were 62% and 68%, respectively.

On the other hand, as conventional example 1, 45% Ag and C were melted and cast.
An ingot of 30% U and 25% In is made, and after hot rolling, it is made into a strip with a thickness of 0.1 mm, and then pressed into a round preform brazing material with an outer diameter of 2.5 mm and a thickness of 0.1 mm. I got 100.

In addition, as conventional example 2, an ingot of 27% AuIn was made by melting and casting, and after hot rolling, it was made into a plate with a thickness of 0.15 m.
After that, 100 circular preform brazing materials having an outer diameter of 2.5 mm and a thickness of 0.15 mm were obtained by press working.

However, the base material was Ag-Pd60 and the outer diameter was 3. Omm,
A disk-shaped contact with a plate thickness of 0.4 mm, Cu, and a head diameter of 3. Omm
, a rivet-like base material with a head thickness of 0.8 m, a foot spacing of 1.5 mm, and a foot length of 2.5 mm was attached to a carbon plate material with a cylindrical groove with an outer diameter of 3.2 mm and a depth of 4 + nm. After inserting the preform brazing filler metal of 1 and conventional example ■ in an electric furnace,
Brazing was performed at 650℃ for 5 minutes in nitrogen hydrogen, and the joint strength and brazing area ratio (the percentage of "brazing area/rivet head diameter") were found, and the results are shown in the table below. Obtained.

Similarly, using the preform brazing fillers of Example 2 and Conventional Example 2 in an electric furnace, brazing was performed at 490°C for 15 minutes in nitrogen hydrogen, and the joint strength and brazing area ratio were investigated. The results shown in the table were obtained.

n=50 n=50 In addition, the average value and R represent the difference between the upper limit value and the lower limit value.

From the results below, it can be seen that the strength of the brazing obtained in Examples 1 and 2 was stable compared to Conventional Examples 1 and 2, with less fluctuation in the joint strength and brazing area.

Although alloy powder was used in the above embodiments, a mixture of metal powders of a plurality of single metals can produce the same effect and can be used in the same manner as the alloy powder. Furthermore, the density can be adjusted by adjusting the sintering temperature, time, and pressing force. Furthermore, the preform brazing material of the present invention is not limited to use in electrical contacts, but is also widely useful in brazing vacuum containers and structures with complex shapes.

(Effects of the Invention) As described above, brazing using the powder sintered preform brazing material of the present invention has the effect of producing a brazed product with stable joint strength because concentrated voids are less likely to occur. It is. Furthermore, since the reliability of brazing can be increased, the number of defective products that have been found through inspection using ultrasonic flaw detection, X-ray photography, etc. can be greatly reduced.

Claims (1)

[Claims] 1) The shape is similar to the bonding area of the base material and the density is 40 to 8.
A powder sintered preform brazing material characterized in that the brazing material is in the range of 5%.