JPH0413496A - Phosphor copper brazing wire and production thereof - Google Patents

Abstract

PURPOSE:To provide the phosphor copper brazing wire having excellent bendability, melt flowability, joint strength, etc., by forming the crystal grain boundaries of the phosphorus copper wire contg. specific wt.% of phosphorus in parallel with the longitudinal direction of the wire. CONSTITUTION:The compsn. of the phosphor copper wire is constituted by incorporating the phosphorus at 8wt.% or over and <=15wt.% therein and consisting the balance of copper and unavoidable impurities. The crystal grain boundaries of the wire are formed in parallel with the longitudinal direction of the wire. The molten phosphor copper alloy 2 having such compsn. is housed into a casting furnace 1 and is cast by a unidirectional solidification method using a casing mold 3, a cooler 6 and pinch rolls 7 to form a casing ingot 5. the casting ingot 5 is then cold worked to the wire. The phosphor copper wire is produced at a high yield in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a phosphor brazing wire having excellent forming processability such as bending, flowability during brazing, bonding strength, etc., and a method for manufacturing the same.

[Conventional technology and its issues]

Phosphorus brazing filler metal is a copper alloy brazing filler metal that normally contains 4 to 8 wt% of P, and is suitable for joining copper or copper alloys, and is often used in electronic and electrical equipment, but in recent years, with the advancement of electronics technology, the above equipment has As a result of miniaturization and miniaturization, improvements in performance such as flowability and bonding strength are strongly desired for phosphor brazed wire.

On the other hand, phosphor brazed wire rods are manufactured by making an ingot using the die casting method, hot extruding it and then cold working it, but the resulting phosphor brazing wire rods have slight bending deformation. It was troublesome to handle because the cracks and rips could become sticky.

In addition, when ingots are continuously cast using the normal horizontal continuous casting method in order to increase productivity, the ingots contain a large amount of P, so the ingots often break during casting, resulting in a significant drop in casting yield. There was a problem.

[Means to solve problems]

In view of the above situation, the present invention has conducted extensive research to determine the influence of P content on flowability and joint strength, and has further determined that the cause of the poor castability of phosphorous brazing solder and the brittleness of phosphorous brazing wire material has been determined.
Hard C precipitated at grain boundaries intersecting the longitudinal direction of the wire
We discovered that u3P is the starting point for cracks,
Further research has led to the completion of the present invention.

That is, the invention of claim (1) provides that phosphorus exceeds 8 wt% and 15
A phosphorous copper brazing wire having a composition of less than wt% and the remainder consisting of copper and unavoidable impurities, the crystal grain boundaries being formed parallel to the longitudinal direction of the wire. It is a wire rod.

In the present invention, the reason why the P content is limited to more than 8 wt% (hereinafter abbreviated as %) and less than 15% is that when P is less than 8%, the flowability of the molten metal is poor, and when brazing the slits, the molten metal This is because P is not sufficiently supplied, and if it exceeds 15%, a large amount of P evaporates during melting and casting, making it impossible to obtain an ingot with an appropriate composition.

In the wire of the present invention, the reason why the grain boundaries of the phosphor brazed wire are formed parallel to the longitudinal direction of the wire is that C
This is to prevent the state in which u3P is precipitated from appearing.

The invention of claim (2) is the method for manufacturing the phosphorous brazing wire, which comprises producing a phosphorous brazing alloy having a composition in which phosphorus is contained in an amount of more than 8% and 15% or less, and the balance is copper and unavoidable impurities. This method is characterized by casting into a linear ingot using a unidirectional solidification method.

The invention of claim (3) is characterized in that the phosphorous copper brazing alloy having the above composition is cast into an ingot by a unidirectional solidification method, and then the ingot is cold-worked into a wire rod of a desired shape. It is something.

In the above, methods such as a heated mold continuous casting method, a rotary pull-up casting method (Czochralski method), and a Bridgman method are applied as the unidirectional solidification method.

Any method such as rolling, swaging, drawing, etc. can be used to cold-work the above-mentioned unidirectionally solidified ingot into a wire rod of a predetermined shape.

Among the above-mentioned unidirectional solidification methods, the heated mold continuous casting method, as shown in FIG. 2 is cooled through the produced ingot 5 and solidified at the exit of the mold, and the solid-liquid interface 8 has a flat shape, resulting in a casting structure of a single crystal or coarse crystals elongated in the longitudinal direction. This is a particularly excellent method as it is composed of grains and the surface of the ingot does not come into contact with the inner surface of the mold, making it extremely beautiful and eliminating the need for external machining, resulting in an ingot with a high manufacturing yield.

[Effect]

Since the phosphorous brazing wire rod of the present invention has a P content limited to more than 8%, the molten phosphorous brazing metal has good flowability during brazing, and therefore the molten phosphorous brazing metal is less likely to be overlaid during brazing. It sufficiently penetrates into the crevices of the materials to achieve good brazing, and since the content of P is high, the strength of the phosphor copper solder is high, resulting in high joint strength.

In addition, since the grain boundaries are formed parallel to the longitudinal direction of the wire, a state in which Cu5P is precipitated on the grain boundaries that intersect with the longitudinal direction of the wire, which causes the wire to become brittle, may occur. Therefore, there is no possibility that the wire rod will be cranked during forming processes such as bending.

In addition, since the phosphor copper solder is cast by a unidirectional solidification method and the obtained ingot is processed by cold working, the grain boundaries are parallel to the longitudinal direction, and therefore, for the same reason as mentioned above, the grain boundaries are parallel to the longitudinal direction. The ingot or processed material will not crack or break during cold working.

(Example〕 The present invention will be explained in detail below using examples.

Example I Phosphorous copper brazing alloy containing various amounts of P in the range of 8.5 to 15% was melted in a melting furnace, and the molten metal was cast in 1. using the hot mold continuous casting apparatus shown in FIG. Each was cast into a linear ingot with a diameter of 6 holes.

That is, the molten metal 2 is transferred to the heater-embedded casting furnace 1,
An ingot 5 produced from a mold 4 whose inner surface has been heated to a predetermined temperature higher than the melting point of the cast metal by a heater 3 is cooled by cooling it with water by a cooler 6, and at a predetermined speed by pinch rolls 7. It was drawn out and cast continuously.

In the above, since the melting point of the phosphorous brazing alloy is lower than the mold inner surface temperature, heat extraction during solidification is not performed from the mold but exclusively through the ingot 5, and as a result, the solid-liquid interface 8 is The resulting ingot 5 had a unidirectionally solidified structure in which crystal grains extended in the longitudinal direction of the ingot 5.

In addition, since the amount of water from the cooler 6 is controlled so that the solid-liquid interface 8 is located near the outlet of the mold 4, the ingot does not rub against the inner surface of the mold as in normal water-cooled casting, and the ingot surface is smooth and free of cracks, and the dimensional accuracy is 1.6.
The results were extremely excellent, falling within the range of ±0.01 mmφ.

Table 1 shows the composition and casting conditions of the phosphorous brazing ingot.

Table 1 Comparative Example 1 A phosphorous brazing ingot was cast in the same manner as in Example 1, except that the amount of P in the phosphorous brazing alloy was changed to 7%.

Comparative Example 2 The same method as in Example 1 was used, except that a phosphorous brazing alloy containing 8.5% P was cast using a horizontal continuous casting device.
A phosphorescent wax ingot was cast.

Each of the phosphor brazing ingots obtained in this manner was either directly drawn or cold drawn to a diameter of 1.4 mm to form a phosphor brazing wire rod, and the wire rods were tested for bendability, vortex flow, etc. The properties and bonding strength were investigated.

The bendability was determined by winding the wire around a 480 mm diameter drum for 10 turns and checking for surface cracks or breaks. The vortex flow property was determined by placing 8-square copper blocks with a gap of 0.2 square meters between them, and determining the degree of infiltration of the molten metal into the gap based on the area ratio.

The bonding strength was determined by dividing the tensile strength of the bonded portion of the copper blocks by the area of penetration of the molten metal. The results are shown in Table 2.

As is clear from Table 2, the products of the present invention (Nos. 1 to 8) had good quality in both the ingots and processed materials.

In addition, there was no cranking of the wire in the bendability test, and the melt flowability and joint strength were high. This value showed a higher value as the P content increased.

On the other hand, the comparison product No. 9.10 had a low P content, so its fluidity and bonding strength were much lower than the product of the present invention, making it difficult to put it into practical use for brazing delicate electronic devices. . In addition, Nos. 11 and 12 had ingots cast by the horizontal continuous casting method, so the crystal structure became polycrystalline, resulting in frequent disconnections in the ingots or processed materials during casting or cold working. The phosphor brazed copper wire had poor bendability.

〔effect〕

As mentioned above, the phosphor brazed wire of the present invention has good bendability and
It has excellent flowability, bonding strength, etc., and is suitable for bonding conductors in minute electronic devices, etc. The wire rod can also be manufactured at a high yield by using ingots cast by the unidirectional solidification method. It has a remarkable industrial effect.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view of the main parts of a heating mold continuous casting apparatus showing one embodiment of the apparatus for implementing the unidirectional solidification method used for manufacturing the phosphor copper brazing wire of the present invention. Half...molten metal;...casting furnace; 3...heater; 4...
... Mold, 5... Ingot, 6... Cooler, 7... Vintage roll, 8... Solid-liquid interface.

Claims (3)

[Claims] (1) A phosphorous-copper brazing wire having a composition in which phosphorus is contained in an amount exceeding 8 wt% and not more than 15 wt%, with the balance consisting of copper and unavoidable impurities, wherein the crystal grain boundaries of the wire are parallel to the longitudinal direction of the wire. A phosphor brazed wire material characterized by being formed. (2) A phosphorus-copper solder alloy containing phosphorus in an amount of more than 8 wt% and less than 15 wt%, with the balance consisting of copper and unavoidable impurities, is cast into a linear ingot by a unidirectional solidification method. A method for manufacturing copper brazing wire. (3) A phosphorous-copper brazing alloy containing more than 8 wt% and less than 15 wt% of phosphorus, with the balance consisting of copper and unavoidable impurities, is cast into an ingot by a unidirectional solidification method, and then the ingot is made into an ingot. A method for producing a phosphor brazed wire rod, which comprises cold working the wire rod into a desired shape.