WO1981000071A1

WO1981000071A1 - Soft brazing process without residue from flux

Info

Publication number: WO1981000071A1
Application number: PCT/JP1980/000145
Authority: WO
Inventors: I Kawakatsu
Original assignee: I Kawakatsu
Priority date: 1979-06-27
Filing date: 1980-06-25
Publication date: 1981-01-22
Also published as: JPS564397A

Abstract

A process for softly brazing an article by placing a brazing filler metal on the article and brazing the article by a suitable heater in a vaporizable solvent vapor. No product such as residue or the like remains on the surface of the article. The brazed article has an attractive gloss since it is in the non-oxidized state, without fear of corrosion and deterioration or the like.

Description

Name of the written invention

Soft brazing method that does not generate residue due to flux

Metal joining method Background technology

In the conventional soft brazing method, the bonding material (hereinafter referred to as “base material”) is first subjected to pretreatment such as pickling and degreasing, and then to an inorganic flux such as an inorganic halide or an inorganic acid, or rosin. Activated rosin to which an organic halogen activator is added is used as a flux, and then soft solder is heated and melted at the joints to perform soft brazing. As described above, the process of soft brazing by the flux inevitably results in the residue generated by the thermal reaction of the flux being deposited on the base material. This residue generally induces significant corrosion after brazing, and is a major obstacle to the reliability of the softened part, such as hygroscopicity, poor insulation, and mold. The following are literatures related to the above.

Reference 1JNotes on Soldering by.W.R.Lewis

Tin Research Institute 1961. Reference 2. Solders and Soldering. By. H. H. Manco.

Mc Graw-Hill Book Co. 1964.

Literature 3. Brazing Engineering K. Ichiro Kawa

Asakura Shoten 1972.

Sentence 4.

American Welding Society Inc. 1977. It is customary to remove flux residues by a cleaning process,

Ο ΡΙ It is extremely difficult to remove, especially for complex structures. In the electronics industry, an organic flux containing an activator is used, but as a practical matter, it is often difficult to perform a cleaning step. Despite this situation, soft brazing that does not produce flux residue has been generally considered to be difficult to date. Disclosure of the invention

In the present invention, no residue due to the reaction of any flux or the like remains on the surface of the base material after soft brazing, and therefore, no post-treatment of residue removal is required. There is no danger of other obstacles. In addition, the surface of the base metal and the surface of the soft solder do not oxidize or contaminate at all, and maintain their original gloss. According to the method of the present invention, first, after the base material is briefly degreased, a soft solder is placed on the joint of the assembly part composed of the base material, and heated in a vapor of a solvent generated from a solvent that is easily vaporized. Melting and inflow of soft solder to perform soft brazing. The solvent of the present invention refers to a liquid organic compound having a boiling point of 30 ° C. or higher, 220 ° C. or lower, and a flash point of 160 ° C. or higher. The joining mechanism at this time is as follows: (1) The oxidizing atmosphere is replaced with solvent vapor, and the atmosphere is made non-oxidizing. (2) The solvent vapor in the gaseous phase has a certain degree of activity, that is, it reduces the oxidized layer on the base metal surface and the soft solder surface by a reducing action and at the same time lowers the surface tension of the soft solder droplets. It is thought to cause wetting. BEST MODE FOR CARRYING OUT THE INVENTION

Next, several examples of the soft brazing method in the present invention will be described. Base material is pure copper (Cu), brass (BS), tin plate (tin-plated iron plate), pure nickel (i), tin (Sn) 50 ^ -I & (Pb) 50% as soft solder, tin (Sn ) 60? |-| & (Pb) 40% eutectic soft solder and tin (Sn)-3.5% silver (Ag). -Nore, Kisire

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Vv'IP Soft brazing was carried out using nine kinds of diethyl hexanol and a mixture of methyl alcohol and trichlene.

In the embodiment of the soft brazing of the present invention, first, the solvent is heated to a temperature several degrees to about 10 degrees higher than its boiling point in a container, and the sample to be soft-brazed in the generated steam from a small nozzle. insert. The brazing temperature was heated on a small electric heater equipped with a sample, and the brazing temperature was measured with a thermocouple. The shape of the sample to be brazed is a square plate with a thickness of 0.320 inch x 20 mm, and the soft brazing material is a disk-shaped material of 0.1 .gr3 <0. Example 1.

On a pure copper plate, soft solder of 50% Sn-50% Pb was brazed. The solvent used was propanol, and showed good brazing properties with a spread area of 10.20 ^ gr at a brazing temperature of 220 ° C. In addition, the surface of pure copper was not oxidized at all and kept pink metallic luster. Example 2.

A Sn—3.5% Ag soft solder was brazed on a pure copper plate. The solvent spread in ethanol at a brazing temperature of 240 ° C and a brazed area was obtained. Example 3.

On a brass plate (BS 3), Sn50% -Pb50 soft brazing was performed. The solvent is acetate and brazing temperature 415. It could be brazed with a spreading area of 4.35 ci / g r with C. In this case, the brass sheet kept its original gold color, and no de-candy phenomena as in ordinary flux soft brazing was observed. Example 4.

On a tin plate (tin-plated iron 5), solder Sn50% —; Pb50% soft brazing ^

I ^PO Was. The solvent was ethanol, the brazing temperature was 230 ° C, and the spread area was 7.7 / kr. Example 5.

A 50% Sn-Pb 50% soft solder was used on a pure nickel plate, and the solvent used was ethanol. At a brazing temperature of 350 ° C, the broad area was 3.45 cd / gr and brazing was possible. Example 6.

On a pure copper plate, soft solder of 60% Sn-40% Pb was brazed. The solvent used was a boiling point of methyl alcohol of 64.6 ° (:, an ignition point of 385 ° C, a brazing temperature of 200, a wide area of 9.65 kr, and a good brazing property.

A 60% Sn—Pb 40 ^ soft solder was brazed on a pure copper plate. The solvent was benzene with a boiling point of 80.1 ° C and an ignition point of 550 ° C. The brazing temperature was 200 ° C and the spread area was 12.5 o! / Gr. Example 8.

On a pure copper plate, soft solder of 60% Sn-40% Pb was brazed. The solvent was dibutanol, the boiling point was 99.5 ° C, and the ignition point was 390 ° C. The spread area was 9.59c77l gr at a brazing temperature of 200 ° C. Example 9.

On a pure copper plate, Sn 60% —Pb 40 soft brazing was performed. The solvent used was a mixture of xylene (a mixture of ortho, meta, and para) with a boiling point of 134 to 142 ° (ignition point of 462 to 525 ° C), a brazing temperature of 200 ° C, and a spreading area of 12.5c ^ Zgr. Example 10

On a pure copper plate, soft solder of 60% Sn-40% Pb was brazed. Solvent is methylhexanol, boiling point 180. Using C, a spreading area of 6.17αΙ gr was obtained at a brazing temperature of 260. Example 1 1.

On a pure copper plate, soft brazing was performed using Sn 60% —; Pb 40% soft solder. The solvent used is 95% methyl alcohol and 5% sodium chloride, and the brazing temperature is 200. In C, the spread area was 10.3 c ^ Zgr. The bonding strength of the soft brazing in the present invention has the same strength as ordinary soft brazing. As described above, the soft brazing method of the present invention was possible even when the base material, the soft brazing material, and the solvent were changed.

As described above, the present invention does not produce any corrosive products or residues due to the reaction of flux or the like, and therefore has the characteristics that no post-treatment is required, the appearance is kept clean after brazing, and no deterioration occurs. At the same time, it is capable of performing pollution-free operations.

[Industrial applicability]

In metal joining, soft brazing is an important process that is indispensable for production as an industrial product that is widely applied to a wide variety of applications such as heat exchangers, piping, and electrical connection of electrical and electronic components. In each of these types of soft brazing, the work is performed using a flux.However, as described above, it is difficult to remove the residue after brazing, and at the same time, this causes corrosion. That is the biggest drawback. As a means for solving this difficult problem, the present invention is a very effective method in the field of joining by means of soft brazing, including heat exchangers and electric and electronic components.

C PI.

Claims

Brazing method characterized by performing soft brazing in the vapor of a solvent that is easy to vaporize c

Eleven

Example

Enclosure

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