JPS61219494A - Flux used for solder joining - Google Patents

Abstract

PURPOSE:To prevent the characteristics of electronic parts from deterioration by forming a flux by using an inorganic or organic flux base-material and silver or silver compound. CONSTITUTION:A solder for joining is formed by mixing a 0.2-0.5wt% silver or silver compound, expressed in terms of silver, into an organic material or an inorganic material consisting of ammonium chloride and zinc chloride, etc. Leads 4, 5 made of copper are connected to a silicon element 1 through solder layers 2, 3, after coating said flux on the element 1. Successively, this intermediate product is coated with a resin sealing layer, after washing its surface, to obtain a button-type electronic part. An ionized halogen on the surface of a material to be joined, is fixed by a silver component contained in the flux, as a silver halide. Accordingly, the characteristics of a finished electronic part is prevented from deterioration.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a flux for soldering, and more particularly, to a flux used for soldering electronic components, it is used to prevent the movement of interfering ions such as halogens. The present invention relates to a solder bonding flux that can effectively prevent characteristic deterioration of electronic components after bonding.

[Technical background of the invention and its problems]

Soldering is an indispensable bonding technique for forming electrical circuits in electronic components.

When performing this solder bonding, flux is generally used for the purpose of improving the solder bonding properties.

Such fluxes are roughly divided into those made of organic materials and those made of inorganic materials. Those made of organic materials are composed of 1 to 5 weight percent rosin or resin, and a solvent and an activator, while those made of inorganic materials are composed of, for example, zinc chloride and water. In this case, the halogen also acts as an activator and facilitates bonding. In general, inorganic materials have a higher concentration of halocene than organic materials, so they are particularly suitable for use with materials that are difficult to bond.

However, when the above-mentioned flux is used to solder join electronic components, such as electrical circuits, the halogens in the flux ionize and move after joining, resulting in deterioration of the electrical characteristics of the resulting electronic components. Problems such as this are occurring. For this reason, conventionally, organic fluxes with low concentrations of NO-Rhodan have been mainly used for soldering electronic components, but in this case, problems such as poor bonding are unavoidable, especially when bonding materials that are difficult to bond. occurs.

On the other hand, even if the above-mentioned problem caused by rodan in the flux is about to occur, it is a well-known fact that rodan in the atmosphere is attached to the surfaces of the parts to be joined. However, after soldering, such halo can also be heated and humidified in the atmosphere and ionized in various processes, resulting in more problems such as electrical circuit leakage and aluminum helding materials. May cause corrosion.

[Purpose of the invention]

The present invention solves such conventional problems, and in particular, the flux used for soldering electronic components, regardless of whether it is an inorganic material or an organic material, can be used in the flux or the parts to be joined after joining. The things that were left behind unavoidably
The purpose of the present invention is to provide a flux for soldering that does not cause deterioration of characteristics of electronic components due to the movement of Rodan ions.

[Summary of the invention]

As a result of intensive research to achieve the above object, the present inventors have found that if a predetermined amount of silver is added to the flux in advance, the ionized metal particles in the flux or on the surface of the objects to be joined can be removed during soldering. Based on the idea that silver rhodanide can be fixed with low solubility, various studies were carried out, and the present invention was completed after actually confirming the effect.

That is, the solder bonding flux of the present invention is characterized by comprising a flux base material made of an organic or inorganic material and silver or a silver compound.

In the solder bonding flux of the present invention, any commonly known inorganic or organic flux may be used as the flux base material, and the component composition thereof is not particularly limited.

The amount of silver or silver compound contained in such a flux base material is not subject to any restrictions, but in particular, the amount of silver based on the total amount of the flux base material and silver or silver compound is 0.2 to 0.5 by weight. It is preferable to set the amount to be % by weight. If the silver content is less than 0.2% by weight, the amount of silver that reacts with halogen ions during soldering is insufficient, making it impossible to sufficiently fix halogen ions.

On the other hand, if the amount exceeds 0.5% by weight, halogen ions may be sufficiently immobilized, but there will be a disadvantage that excess silver will remain after the reaction. Particularly preferable silver content is 0
．． It is 3 to 0.4% by weight.

The solder bonding flux of the present invention described above can be easily manufactured as follows. That is, silver or a silver compound may be added and mixed in the above-mentioned amount to a flux base material made of a generally used organic or inorganic material as described above. Examples of the silver compound used include silver oxide and silver carbonate, and the amount of these compounds to be used is determined so that the silver content falls within the above-mentioned range. Incidentally, if the flux base material to be used has a high degree of activity, silver is suitable, whereas if the flux base material used has a relatively low degree of activity, a silver compound such as silver oxide is suitable. This is to suppress unexpected reactions when silver is blended into the flux base material.

Furthermore, the solder material itself contains the compounding amount of "-", that is, 0.
．． Even if it contains silver in the range of 2 to 0.5% by weight and is used in combination with a conventional flux that does not contain silver, the same effect as the solder bonding flux of the present invention can be obtained.

[Embodiments of the invention]

Example 1 (1) Production of solder bonding flux Zinc chloride 65
The solder bonding flux of the present invention was produced by mixing 3 parts by weight of ammonium chloride, 1 part by weight of ammonium alginate, 0.2 parts by weight of silver powder having a particle size of 325 mesh, and 30.8 parts by weight of water. .

(2) Junction evaluation test for electronic components A button-type diode as shown in FIG. 1 was manufactured. That is, after forming a PN junction by the diffusion method, one coat of the flux obtained above is applied on both electrode surfaces of the silicon element 1, which has Ni electrodes (not shown) formed on both sides, and then the solder layer 2 is applied. Leads 4 and 5 made of copper were connected through and 3. Solder layers 2 and 3 are Pb-1wt%Sn preform solder (diameter 3B).

The bonding was performed in a hydrogen furnace. Thereafter, the silicon element 1 was mesa-etched and the surface was cleaned, and then a silicone RTV, a linal protective layer 6, and a resin sealing layer 7 made of epoxy resin were sequentially formed to complete a tan-type diode.

Furthermore, we measured the high temperature reverse bias characteristics of this tan-type diode. That is, temperature 175°C1 reverse bias voltage2
Under the condition of 00■, the reverse current value (engineering FL
) changes were investigated. The average value of the 10 products manufactured above was measured, and the obtained results are shown in FIG. 2 by a broken line. Furthermore, this issue? After the above test, the tan type diode was disassembled and the chlorine content of the element was analyzed, and the result was 3 μg/piece.

Example 2 As a flux, a commercially available ronone-based flux (Gammalux; trade name, manufactured by Hoshu Metal Industry Co., Ltd.) with a chlorine concentration of 0.2% by weight, to which 0.2% by weight of silver oxide was added and mixed well, was used. After manufacturing a button-type diode in exactly the same manner as in Example 1, high-temperature reverse bias characteristics were similarly measured. The fruit of the sojourn is shown in Figure 2 with a dash-dotted line. same,
The chlorine content of the element was 4 μg/piece.

Comparative Example A tan diode was manufactured in exactly the same manner as in Example 1 above, except that no flux was used, and then its high temperature reverse bias characteristics were measured. The results are shown in Figure 2 as a solid line. In addition, the chlorine content of the element is 0.3μg/
It was individual.

Reference Example The same preform was used by adding 0.5 weight of silver to the same solder used in Example 1, except that a zinc chloride flux to which no silver was added was used. After manufacturing a button-type diode in the same manner as in Example 1 above, high-temperature reverse bias characteristics were measured. The results are shown in FIG. 2 by a two-dot chain line. Note that the chlorine content of the element was 3 μg/piece.

[Effects of the invention] As is clear from the above explanation, when electronic parts are joined using the solder joining flux of the present invention, the resultant element is better than when no flux is used. It was confirmed that the electrical characteristics were far superior (M
Figure 2). In other words, the amount of chlorine contained in the obtained device using the flux of the present invention is much higher than that of the device not using the flux, but on the other hand, the high temperature bias characteristics are dramatically improved. Considering from
It has been demonstrated that the silver contained in the solder bonding flux of the present invention fixes halodane, which acts as an interfering ion.

Furthermore, it was confirmed that the same effect as above can be obtained by combining a solder containing silver and a flux not containing silver.

[Brief explanation of drawings]

Figure M1 is a sectional view of a tan diode 15 manufactured using the solder bonding flux of the present invention, and Figure M2 is a diagram showing the high temperature reverse bias characteristics of the tan diode. 1... Silicon element, 2.3... Solder layer, 4, 5
...Lead.

Claims (1)

[Scope of Claims] 1. A solder bonding flux characterized by comprising a flux base material made of an organic or inorganic material and silver or a silver compound. 2. The solder bonding flux according to claim 1, wherein the content of the silver or silver compound is 0.2 to 0.5% by weight of the total weight of silver.