JPS60213396A - Binder for paste solder - Google Patents

Abstract

PURPOSE:To prevent sepn. and corrosion of solder powder during storage of the paste obtd. from a binder and the solder powder by dissolving and mixing a prescribed ratio each of toluene, acrylic resin and org. gelling agent in and with butyl acetate thereby forming said binder. CONSTITUTION:40-70wt% Toluene is dissolved in the butyl acetate. 10-40wt% Acrylic resin is dissolved into such soln. 0.2-2wt% Org. gelling agent is further mixed therewith, by which the binder for the paste solder is obtd. The paste solder obtd. by mixing such binder and the solder powder has the excellent effect of preventing sepn. of the solder powder and corrosion of the solder powder during storage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paste solder binder used for brazing in a non-oxidizing atmosphere.

Conventionally, soldering of base materials that are extremely susceptible to oxidation has been carried out in a non-oxidizing atmosphere such as a vacuum or a reducing atmosphere. As the brazing material used in this case, a paste brazing material made by mixing a brazing powder and a binder has recently been adopted.

The brazing filler metal that is the main component of this solder paste includes powdered brazing filler metals such as AuNi brazing powder, AgC
U wax powder, AgPd wax powder, etc. are used, but the binder is required to have the following properties.

+11 No residue such as carbon remains when used in a non-oxidizing atmosphere.

(2) It should not separate from the wax powder and form two layers during storage.

(3) Do not corrode the wax powder.

(4) Do not oxidize the base material to be brazed.

(5) Brazing should not get wet or run off from the part.

(61 Do not splash during heating.

(7) Good workability.

In other words, as a binder for paste soldering, it is desirable to have a non-corrosive binder that is viscous and does not easily evaporate at room temperature, and that does not decompose and evaporate within 300°C during brazing and does not leave any residue. It is rare.

However, none of the binders conventionally used in paste soldering satisfies the above conditions.

Therefore, in order to satisfy the above-mentioned conditions required for a binder composition, the inventors have determined that the polymer material having a certain molecular weight, its solvent, and the wax powder, which has a heavy specific gravity when made into a paste, should not be separated. Focusing on the need for a viscosity modifier to impart viscosity to the binder, we conducted research on polymeric materials, solvents for dissolving them, and viscosity modifiers, and as a result, we dissolved toluene in acrylic resin and butyl acetate. We have discovered a binder for wax paste that satisfies the above conditions by combining an organic gelling agent as a viscosity modifier with the liquid.

The binder for wax paste of the present invention contains toluene 40~
Add 1 part of acrylic resin to a solution of 7 kt% dissolved in butyl acetate.
Dissolve 0-40-t% and further add 0.2-2% organic gelling agent.
It is made by mixing wt%.

The reason for using a solution of 40-70% toluene dissolved in butyl acetate as a solvent in the binder for wax paste of the present invention is to improve workability and to prevent paste wax from flowing from the brazed area. Tamade, toluene 4
If it is less than 0-t%, the vapor pressure of butyl acetate is low, so the solvent will not dry properly and will flow away from the brazed area.70
This is because, if it exceeds -t%, toluene and butyl acetate will not dissolve in each other and will separate into two layers, resulting in a non-uniform solution.

The reason why the proportion of acrylic resin was set to 10 to 40 wt% is as follows.
If it is less than 10-t%, when it is mixed with solder powder and made into a paste, brazing has poor wettability to the part and sufficient brazing cannot be achieved, and if it exceeds 40-t%, when used in a non-oxidizing atmosphere, This is because a large amount of carbon, etc. remains or splatters during heating, making it unsuitable as a binder. The reason why the organic gelling agent is 0.2 to 2 wt% is that less than 0.2 wt% will not gel, so when mixed with wax powder and made into a paste, the binder and wax powder will separate into two layers.
If it exceeds ht%, the gelling effect will be strong (solidification will occur), making it impossible to use it as a binder.

Next, examples of the binder for paste brazing according to the present invention will be described.

After melting 25iyt% of acrylic resin powder in a solution of 50wt% of toluene dissolved in butyl acetate, Q and 5wt% of Gelol D (M) as an organic gelling agent were mixed therein and thoroughly stirred. , 70℃± in a hot water bath
The mixture was heated at 5'C for 1 hour, and then allowed to cool to room temperature in the air to form a gel, resulting in an agar-like binder.

10 wt% of the agar-like binder of the example thus created
90 wt % of wax powder of 18% AuNi was mixed and stirred to form a paste wax.

In this paste wax, the wax powder and binder did not separate during storage, and the wax powder did not corrode.

However, when this paste solder was applied to the base material of the iron piece and was repeatedly brazed at 970°C in a hydrogen atmosphere, good brazing was achieved without any carbon residue or the like.

In contrast, conventional example 1, JAF451 manufactured by Darbo Blaze Co., Ltd.
4 Paste wax and Paste wax using Nikro Blaze Cement S manufactured by Wall Kono Monoi of Conventional Example 2 A to 10wL% binder of Clo Blaze Cement S
(U N + 18% wax powder mixed and stirred at 90 wt%), the wax powder and binder separated during storage, and the wax powder of Conventional Example 1 corroded. When these conventional brazing pastes were applied to the base material of an iron piece and brazed in layers at 970° C. in a hydrogen atmosphere, residues such as carbon were produced and the quality of the brazing was poor. Further, the paste solder of Conventional Example 2 sputtered during heating.

As can be seen from the above explanation, if the paste solder binder of the present invention is appropriately mixed and stirred with the solder powder to form a paste solder, the solder powder will not separate during storage and will not corrode the solder powder. Furthermore, when coated brazing is applied to a base material, it does not oxidize the base material, and it does not splatter during heating during brazing, and even when used for brazing in a non-oxidizing atmosphere, carbon This has the excellent effect of producing a paste wax that does not leave any residue.

Applicant Tanaka Kikinzoku Kogyo Co., Ltd.

Claims (1)

[Claims] A binder for paste brazing, which is prepared by dissolving 10 to 40 wt% of an acrylic resin in a solution of 40 to 70 wL% of toluene dissolved in butyl acetate, and further mixing 0.2 to 2 wt% of an organic gelling agent.