JPS63160795A - Binder for paste solder - Google Patents

Abstract

PURPOSE:To prevent corrosion of solder powder and oxidation of base metals and to improve soldering workability by mixing 1 or 2 kinds of polybutene and polyisobutyrene and org. gelling agent respectively at prescribed % with specific weight % of n-hexane. CONSTITUTION:The binder for paste solder is obtd. by mixing 30-80% 1 or 2 kinds of polybutene and polyisobutyrene with 20-70% n-hexane, and further, adding 0.25-3% org. gelling agent thereto, then agitating and heating the mixture. The corrosion of the solder during storage is prevented by the gelation of the binder and the oxidation of the base metals when the solder is coated thereon are prevented if the paste solder is prepd. by adequately mixing and agitating this binder and the solder powder. Further, the splashing of the binder during soldering is obviated by the viscosity adjustment of the binder and the generation of residue is obviated as well. The soldering workability is, therefore, 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 that is a mixture of wax powder and pie powder has recently been adopted.

The brazing filler metal, which is the main component of this paste solder, includes powdered brazing filler metals such as AuNi brazing powder, Ag
Cu solder powder, ΔgPd solder 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, as a binder for paste brazing, it is desirable to have a non-corrosive binder that is viscous and does not easily evaporate at room temperature, and that does not separate or splatter or leave any residue during brazing at temperatures up to about 450°C. It is rare.

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

Therefore, in order to satisfy the above-mentioned conditions required for a binder composition, the present inventors separated a polymer material having a certain molecular weight, a solvent thereof, and a wax powder having a heavy specific gravity when made into a paste. Focusing on the need for a viscosity modifier to give viscosity to the binder to prevent it from becoming viscous, we conducted research on polymeric materials, solvents for dissolving them, and viscosity modifiers, and found that n-hexane, polybutene, and polyisobutylene were used. We have discovered a binder for wax paste that satisfies the above conditions by combining one or two of the above and an organic gelling agent as a viscosity modifier.

(Means for Solving the Problems) The binder for wax paste of the present invention comprises n-hexane 2
0 to 70-t%, 1 of polybutene, polyisobutylene
30-80-t% of one or two species and 0.25% of an organic gelling agent
~3 wt%.

In the binder for wax paste of the present invention, the reason why 20 to 7 h+t% of n-hexane is used as a solvent is to improve workability and volatility.
If it is less than w+%, it will easily separate from the wax powder during storage and become 2N, and if it exceeds 70 wL%, it will be difficult to fix the volatilized wax powder.

30~1 type or 2 types of polybutene and polyisobutylene
The reason for setting it at 70-t% is that if it is less than 30-1%, when it is mixed with solder powder and made into a paste, brazing has poor wettability to the parts, and sufficient brazing cannot be achieved, and if it exceeds 70-t%, it cannot be stored. This is because the wax powder separates out and becomes 2N, making it unsuitable for use as Ba Ingu.

The reason for setting the organic gel agent to 0.25 to 3 wt% is that 0.2
If it is less than 5 tvt%, it will not gel, so when mixed with wax powder to make a paste, the binder and wax powder will separate into two layers cL, and if it exceeds 3 wt%, the gelling effect will be strong and solidify, so the binder It can no longer be used as such.

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

(Example) After mixing n-hexane with one or two of polybutene and polyisobutylene as shown in the table below, rheosin (CASTOROIL) was added as an organic gelling agent.
COMPANY) were mixed and sufficiently stirred, heated in a hot 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.

Agar-like binder 10 of Examples 1 to 3 thus produced
A wax paste was prepared by mixing and stirring 901% of wax powder of 18% AuNi based on wt%.

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.

On the other hand, in conventional example 1, IAI'45 manufactured by Darbo Blaze Co., Ltd.
14 paste wax and conventional example 2 using Nikro Blaze Cement S made by Wall Kono Monoi.
Mixed and stirred 90wt% of 18% Ni wax powder)
In conventional example 1, wax powder and binder separated during storage.
The paste of the wax was corroded by the wax powder. 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.

(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] A binder for paste brazing comprising 20 to 70 wt % of n-hexane, 30 to 80 wt % of one or both of polybutene and polyisobutylene, and 0.25 to 3 wt % of an organic gelling agent.