JPS63160791A - Binder for paste solder - Google Patents

Abstract

PURPOSE:To prevent corrosion of solder powder and oxidation of base metals and to improve brazing workability by mixing polystyrene and org. gelling agent respectively at prescribed % with specific wt.% of n-octane to form the titled binder. CONSTITUTION:The binder for paste solder is obtd. by mixing 40-80% polystyrene, by weight and 0.25-3% org. gelling agent with 20-60% n-octane. mixing and agitating the mixture and heating the same. The sepn. and corrosion of the solder powder during storage are prevented and the oxidation of the base metals when the solder is coated on the base metals is prevented if the paste solder is prepd. by adequately mixing the solder powder and this binder. Since the binder is gelled, the splashing of the binder during soldering and the remaining of residue are obviated. The brazing workability is thereby improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a paste solder binder used for brazing in a non-oxidizing atmosphere.

(Prior Art and its Problems) Conventionally, brazing of base materials that are extremely susceptible to oxidation has been performed 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, 8gPd wax powder, etc. are used, but the binder is required to have the following properties.

(1) 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.

(6) Do not splash during heating.

(7) Good workability.

In other words, the binder for paste solder is non-corrosive and has a viscous thread that does not easily volatilize at room temperature, and during brazing it separates and evaporates within about 450 degrees Celsius and does not splatter or leave any residue. something is desired.

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

Therefore, the present inventors believe that in order to satisfy the above conditions required for a binder composition, it is not necessary to separate the polymeric material having a certain molecular weight, its solvent, and the wax powder, which has a heavy specific gravity when made into a paste. Focusing on the need for a viscosity modifier to impart viscosity to the binder, we conducted research on polymer materials, solvents for dissolving them, and viscosity modifiers, and found that n-octane, polystyrene, and viscosity modifiers We have discovered a binder for wax paste that satisfies the above conditions by combining it with an organic gelling agent.

(Means for solving the problems) The binder for wax paste of the present invention has n-octane 2
It is made by mixing 0 to 5 Qwt% of polystyrene, 40 to 80 wt% of polystyrene, and 0.25 to 3 wt% of an organic gelling agent.

The reason why 20 to 60 wt% of n-octane is used as a solvent in the binder for wax paste of the present invention is to improve workability and volatility.
If it is less than 60 wt%, it will easily separate from the wax powder and form two layers during storage, and if it exceeds 60 wt%, it will easily volatilize and it will be difficult to fix the wax powder.

The reason why the percentage of polystyrene was limited to 40-801% is 4.
If it is less than 0wt%, when mixed with solder powder and made into a paste, brazing will have poor wettability to the parts, and sufficient brazing will not be possible, and if it exceeds 80wt%, the solder powder will separate during storage and form two layers. This is because it is unsuitable as a binder. The reason why the organic gel was set at 0.25 to 3 wt% is that 0.25 to 3 wt% was used.
If it is less than 25 wt%, it will not gel, so when mixed with wax powder and made into a paste, the binder and wax powder will be 2Ji! If it exceeds 31%, the gelation effect will be strong and it will solidify, 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.

(Example) After mixing 45 wt% of n-octane with 53 wt% of polystyrene, rheosine (CA) was added as an organic gelling agent.
(manufactured by STOROIL COMPANY) and sufficiently stirred, heated in a water bath at 45° C.±5° C. for 1 hour, and then left to cool to room temperature in the air to gel, resulting in an agar-like binder.

10 wt% of the agar-like binder of the example thus produced
A paste wax was prepared by mixing and stirring 90 wt % of a wax powder with A u N i of 18%.

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 residue such as carbon.

In contrast, conventional example 1, IAF451 manufactured by Darbo Blaze Co., Ltd.
4. Paste wax using Heast wax and Nikro Blaze Cement S manufactured by Wall Kono Monoi of Conventional Example 2.Au to 10wt% binder of Clo Blaze Cement S
In the paste solder (mixed and stirred with 90 imt% Ni 18% solder powder), the solder powder and binder separated during storage, and in the paste solder of Conventional Example 1, the solder powder corroded. When these conventional brazing pastes were applied to the base metal of an iron piece and laminated and brazed at 970"C in a hydrogen atmosphere, carbon residues were generated and the quality of the brazing was poor. Furthermore, the paste of Conventional Example 2 The wax sputtered during heating.

(Effects of the Invention) As can be seen from the above explanation, if the binder for paste brazing of the present invention is appropriately mixed and stirred with wax powder to make a paste wax, the wax powder will not separate during storage and will not corrode the wax powder. In addition, over-brazing does not oxidize the base material when applied to the base material, and does not splatter during heating for brazing, and can be used for brazing in non-oxidizing atmospheres. This has the excellent effect of producing a paste wax that does not produce residues such as carbon.

Claims (1)

[Claims] 20-60 wt% n-octane, 40-40 wt% polystyrene
A binder for paste soldering comprising a mixture of 80 wt% and an organic gelling agent of 0.25 to 3 wt%.