JPH0762571A - Method for soldering material including metallic member - Google Patents

Abstract

PURPOSE:To provide the method for soldering electronic materials including metallic members without using a flux by preventing the oxidation of the metallic surfaces to be soldered of the electronic materials during storage and transportation. CONSTITUTION:The materials including the metallic members hermetically preserved together with rust preventive packages in gas barrier type containers are soldered without using the flux. As a result, the materials including the metallic members are held in a reducing atmosphere where oxygen, moisture and corrosive materials do not substantially exist and a reducing gas coexists by the extremely simple and low-cost method, by which the oxydation of the metallic surfaces is prevented and the good soldering is easily made possible. The need for flux washing by an org. halide solvent is eliminated after the soldering. The washing stage is thus simplified and the cost thereof is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing a decrease in solder adhesion during transportation or storage and solder-bonding a material including a metal member such as an electronic material without using a flux.

[0002]

2. Description of the Related Art When a material containing a metal member is exposed to air during storage or transportation, the metal member easily oxidizes to form an oxide film on the metal surface, so that the solder adhesiveness thereof is rapidly lowered. Therefore, upon solder bonding, post flux is used to remove the oxide film on the metal surface and facilitate solder bonding. However, post flux usually contains a halogen compound, and when a post flux containing a large amount of a halogen compound is used for solder bonding of a material having a metal member, especially an electronic material, the residual halogen compound causes metal corrosion and deterioration of electrical insulation. Cause Therefore,
After the soldering process, the electronic material is washed with water containing an organic halogen-based solvent such as CFC or a surfactant. However, CFCs such as trichlorofluoromethane, trihaloethanes, trihalomethanes, and other halogen-based solvents are banned by international treaties in order to prevent the destruction of the global environment (ozone layer), and fluxes containing many halogen compounds. Is no longer applicable to solder bonding of electronic materials. Further, the water washing has a problem that a large amount of cost is required for the treatment of waste water containing heavy metals and organic substances after washing and further for the drying.

Under these circumstances, a so-called no-cleaning technique has recently been used in which a post-flux containing a small amount of a halogen compound (referred to as a low-activity post-flux) is used and a halogen-based organic solvent is not required after solder bonding. Is being developed. In this case, the amount of residual halogen on the mounting substrate, on which components and the like are mounted and solder-bonded, needs to be suppressed to 14 μg / inch ² or less, and the amount of halogen contained in the low activity post flux used needs to be reduced as much as possible. .

However, the low activity post-flux has a small ability to remove oxides, and in order to prevent the oxidation of metal members during storage or transportation, usually, a method of hermetically packaging electronic materials together with a desiccant or a storage container is used. Although a storage method such as a method of substituting the gas with an inert gas has been adopted, it was not always satisfactory. For example, with an inert gas replacement method using nitrogen or argon, it is not easy to completely replace oxygen in the storage system, and even if it is completely replaced, oxygen and water will not permeate from the packaging material during storage. , The oxygen concentration and humidity in the storage system rise and the metal surface is oxidized. Further, in the method using a desiccant, even if it is completely dehumidified, oxidation occurs, but with the passage of time, the humidity increases due to the moisture permeated from the packaging material and the moisture contained in the object to be stored, and the metal surface is oxidized. In any case, in the conventional storage method, there is often a problem in the solder adhesiveness when applying the non-cleaning technique in which the solder is adhered by the low activity post flux, and the solution is demanded.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solder bonding method for electronic materials, which does not use flux, for the purpose of solving the problems of the above-mentioned non-cleaning solder bonding technology. The present inventors have conducted extensive studies in view of the problems of the above-mentioned conventional techniques, and as a result, an electronic material including a metal member is formed into a gas barrier container together with a rust preventive package that absorbs oxygen, moisture and acid gas. Prevents metal oxidation by storing in a sealed manner,
Moreover, they have found that they can be satisfactorily solder-bonded without using a flux by drying, and have reached the present invention.

[0006]

The present invention relates to a solder bonding method for a material containing a metal member, and more specifically, a material containing a metal member is hermetically stored together with a rust preventive package in a gas barrier container. The present invention relates to a solder bonding method for a material containing a metal member, which comprises solder bonding a material containing a metal member without using a flux. The solder bonding method of the present invention, a material including a metal member is a gas barrier container oxygen,
Keeping electronic materials in an atmosphere in which oxygen, moisture and corrosive substances are substantially absent and reducing gas coexists by sealing and storing together with a rust preventive package that absorbs moisture and acid gases. This prevents the formation of an oxide film on the metal surface of the metal member and solder-bonds the material including the metal member without using a flux.

The solder bonding method of the present invention can be applied to any object including a metal to which the method of the present invention can be applied as a member, and the material including the metal member may be a simple metal. . Examples of the metal to be solder-bonded include metals such as copper, silver, iron, zinc, lead, tin, nickel, and gold, and an alloy containing two or more of these metals may be used. In the presence of oxygen, an oxide film is formed on the surface of these metals, and it is considered that the formation of the oxide film is promoted by the presence of water and corrosive substances such as sulfur compounds and halogen compounds. According to this, the formation of the oxide film is prevented, and the solder bonding can be performed without using the flux.

The method of the present invention is preferably applied to electronic materials as materials containing metal members. Electronic materials including metal members are mainly composed of metal and plastic materials,
Soldered on the metal part. Examples of electronic materials include basic elements and wiring boards. Basic elements include electronic parts such as cables, resistors, capacitors, relays, semiconductor devices and waveguides. The wiring board is formed by forming a metal foil such as a copper foil in a pattern and laminating it with a plastic layer. This wiring board may be further plated with silver, tin, solder or the like, or may be coated with a pre-flux containing rosin or polyester resin as a main component.

The present invention is also applicable to a solder metal to which the above electronic material is bonded by soldering. Solder metals include molded ones, powdered ones and creamy ones. The particle size of the powdered solder metal is 10 to 70 μm, preferably 10 to 70 μm.
It is 50 μm.

In the present invention, the rust preventive agent package is a deoxidizer that easily absorbs oxygen in a dry system, preferably oxygen, and moisture and corrosive substances such as sulfur compounds and halogen compounds. A deoxidizer package that can be used is used. The rust preventive package is sealed with a material containing a metal member to absorb oxygen, moisture and corrosive substances in the storage container so that the oxygen concentration is 0.5% or less, preferably 0.1%.
As described below, the atmosphere in the sealed system can be maintained in a substantially oxygen-free state that suppresses metal oxidation. In particular, it removes water and corrosive substances such as sulfur compounds and halogen compounds, which are known to promote metal oxidation, from within the container within 5 hours, and also removes these substances that permeate from the container. By doing so, it is possible to suppress metal oxidation that occurs while oxygen is lost.

Regarding the rate of oxygen absorption by the rust preventive package, if the rate is slow, the metal may be oxidized before the oxygen-free state is reached. On the other hand, if the oxygen absorption rate is too fast,
When handling the rust preventive package, it will become more effective due to exposure to the atmosphere, or heat will increase. Therefore, the oxygen absorption rate of the rust preventive package is determined by the time required to absorb oxygen in the sealed system and reach a substantially oxygen-free state, for 2 hours to 5 days, preferably 3 hours to 3 days. Is adjusted to a speed that ranges from 5 hours to 2 days.

The rust preventive used as the rust preventive package is
Specifically, a rust preventive agent composition containing an unsaturated fatty acid compound or an unsaturated fatty acid compound and a chain hydrocarbon compound having an unsaturated group as a main component can be mentioned. The rust preventive composition is
In addition to the unsaturated fatty acid compound as the main ingredient or the unsaturated fatty acid compound and the chain hydrocarbon compound having an unsaturated group, it is a composition comprising an oxidation promoting substance, a basic substance and an adsorbent.

The unsaturated fatty acid compounds used herein are unsaturated fatty acids having 10 or more carbon atoms, esters and salts of the unsaturated fatty acids. Examples of unsaturated fatty acid compounds include unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, parinaric acid, dimer acid, ritinoleic acid and ricinoleic acid, esters of these unsaturated fatty acids and esters thereof. Examples thereof include fats and oils and metal salts of the above unsaturated fatty acids.

The chain hydrocarbon compound having an unsaturated group is a chain hydrocarbon having 10 or more carbon atoms and one or more double bonds between carbon atoms, or an oligomer or polymer thereof and a derivative thereof. As a substituent of the derivative, for example, a hydroxyl group, a formyl group, etc. may be present. Examples of the chain hydrocarbon compound having an unsaturated group include butadiene, isoprene, oligomers and polymers of 1,3-pentadiene, and squalene.

The main component of the rust preventive composition is preferably a transition metal salt of an unsaturated fatty acid or a mixture of a transition metal salt of an unsaturated fatty acid and an unsaturated fatty acid, or a hydrocarbon having an unsaturated group in the mixture. A polymer is added. The unsaturated fatty acid compound or the chain hydrocarbon compound having an unsaturated group may be mixed with impurities as long as the object can be achieved.

The oxidation-promoting substance plays a role of a catalyst for the oxygen absorption reaction by the main agent. As an oxidation promoter,
Examples thereof include compounds of transition metals such as iron, cobalt, chromium, copper and nickel. As the transition metal compound, for example,
An inorganic acid salt such as a sulfate, a hydrochloride or a nitrate, an organic acid salt such as a fatty acid salt or an unsaturated fatty acid salt, or an amine complex of a transition metal is used. It is desirable that the oxidation promoting substance is uniformly mixed with the main component. Of course, as described above, it may be a metal salt of an unsaturated fatty acid used as the main ingredient.

The basic substance absorbs corrosive substances such as sulfur compounds and halogen compounds that diffuse through the storage container and acidic substances produced by the oxygen absorption reaction of the main agent such as unsaturated fatty acid compounds. There is no particular limitation as long as it achieves the purpose. Preferred basic substances include alkali metal or alkaline earth metal oxides, hydroxides, carbonates and organic acid salts, and organic amines.

The adsorbent substance absorbs water,
Preferably, it also absorbs an acidic substance.
Further, the adsorbent substance plays a role of a carrier for supporting a main agent such as an unsaturated fatty acid compound and a chain hydrocarbon compound having an unsaturated group to increase a contact area with oxygen and increase an oxygen absorption rate. Specific examples of the adsorbent include paper made of natural pulp, silica gel, activated carbon, zeolite, and activated clay.

As described above, the rust preventive composition comprises the main agent, the oxidation-promoting substance, the basic substance and the adsorbent, and the ratio of each component of the composition is usually 100 parts by weight of the main agent. , 0.01 to 10 parts by weight of the oxidation promoting substance, 1 to 1000 parts by weight of the basic substance, 10 to 1000 parts of the adsorbing substance.
A range of parts by weight is preferred. The above-mentioned rust preventive composition is prepared by mixing the above components with a liquid substance supported on an adsorbing substance. The shape is not particularly limited, and it is appropriately prepared and used in the form of granules, tablets or sheets.

The above rust preventive composition has an oxygen transmission rate of 100.
Used as a package wrapped in a packaging material having air permeability of 0 ml / m ² · atm · Day or more. The breathable packaging material and the constitution are not particularly limited, but for example, a packaging material obtained by filling a breathable packaging material of a laminated material having a base material such as paper or non-woven fabric and a perforated plastic film or sheet with a rust preventive composition. The periphery of is heat-sealed to form a package.

Further, a package packaged in a breathable packaging material has an oxygen permeability of 1000 ml / m ² · atm · Day or more,
It may be double-packed in a breathable packaging material having a moisture permeability of 1 g / m ² · Day or more, and a dust collection efficiency of 0.3 μm or more when air is passed, which is 50% or more. The form of the rust preventive package is not particularly limited, and examples thereof include a pouch, a sheet, and a blister package.

In the present invention, as the gas barrier container used for storing electronic materials, bags, cases, cans and the like made of plastic or metal having gas barrier properties are used. The gas barrier container has an oxygen permeation rate of 5 ml / Day or less per 100 ml volume, preferably 1 m.
1 / Day or less, and a water permeation rate of 10
It is 5 g / Day or less, preferably 1 g / Day or less per 0 ml.

Specific examples of the gas barrier container include a case made of synthetic resin such as polyethylene, polypropylene, nylon, polyester, vinyl chloride, polystyrene and polycarbonate, or vinyl chloride,
Examples thereof include a bag made of a laminated material formed of a film or sheet of vinylidene chloride, nylon, polyethylene, polypropylene, polyester or the like. If the material is a plastic film or sheet, to ensure gas barrier properties,
Aluminum, silicon oxide, selenium oxide, etc. may be vapor-deposited and used on the surface. Further, a metal foil such as an aluminum foil may be used by laminating it with a plastic film. Furthermore, as a gas barrier container, iron,
There are metal cans made of tin, stainless steel, and aluminum, and plastic packing materials are also used for the metal cans. The material of these gas barrier containers may be subjected to antistatic treatment.

According to the solder bonding method of the present invention, the solder metal can be heated and melted and bonded to the metal surface of the object to be bonded without using flux. The solder metal used is usually an alloy of tin and lead with a tin content of 5 to 95%.
belongs to. There is a bonding method using cream solder in which solder metal powder is made into a paste. In this case, cream solder is applied onto the wiring board and heated by infrared rays to 200 to 300 ° C. to be bonded.

[0025]

EXAMPLES The present invention will be described below with reference to examples. The present invention is not limited to the examples. Example (preparation of test piece) Copper plate (size width 1.27 mm ×
Copper, silver and solder were each plated to a thickness of 5 μm in a length of 60 mm and a thickness of 0.5 mm. The copper plate after plating is washed with water and then immersed in ethanol at 23 ° C.,
It was dried by blowing air at 24 ° C and plated with copper, silver and solder 3
Created different kinds of test pieces.

(Production of rust preventive package) 0.5 g of polyputagen (viscosity 200 poise) and 0.5 g of soybean oil fatty acid
5 g of granular diatomaceous earth was impregnated with a solution prepared by dissolving 0.2 g of cobalt naphthenate in 1.0 g of the mixture.
1 g was coated to produce a granular composition. This granular composition (total weight 6.3 g) and granular calcium oxide 2.5
g was packaged in a breathable packaging material (70 × 70 mm) made of a laminate of paper / open-pore polyethylene film with the polyethylene film surface inside, and the periphery was heat-sealed to produce a rust preventive package.

(Gas Absorption Performance of Antirust Agent Package) Antirust Agent Package
Silicon oxide vapor deposition composite film (oxygen permeation rate)
0.5 ml / m ² ・ 24Hr ・ Atm, moisture permeability 0.1g / m² 
・ Three-sided seal bag (size 220 × 30) made with 24 hours
0 mm, surface area 0.11 m² , Oxygen transmission rate 0.044
ml / 24Hr), humidity 65RH%, hydrogen sulfide 7p
Enclose 500 ml of air containing pm and heat seal the opening
And sealed. Put a bag in which this rust preventive package is sealed in 25
Oxygen concentration, humidity and sulfurization in a sealed bag when left at ℃
Changes in hydrogen concentration over time are shown in FIG. 1, FIG. 2 and FIG.
3 shows.

(Preservation of test piece) One of the above-mentioned three kinds of test pieces and one rust preventive agent packaging body were put into a three-side sealing bag (size 220 × size) of the same silicon oxide vapor-deposited composite film as described above.
300 mm) and 500 ml of air were sealed. Once the test piece and the rust preventive package were sealed,
After keeping at 25 ° C. for 1 day, it was stored at 40 ° C. under an atmosphere of RH of 95% or more. Table 1 shows the oxygen concentration and humidity in the sealed bag during storage, and Table 2 shows the concentration of the reducing gas detected by gas chromatography. Table 3 shows the discoloration status of the stored test pieces.

[0029]

[Table 1] Changes over time in oxygen concentration and humidity in the storage system

[0030]

[Table 2] Changes over time in the concentration of reducing gas in the storage system Note) Butyal: Butyraldehyde

[0031]

[Table 3] Discoloration of stored test pieces Note 1) Discoloration status-: No discoloration +: Distinguishable slight discoloration ++: Significant discoloration +++: Discoloration on the entire surface

(Solder Wetting Adhesion Test) After taking out a test piece which was sealed with a rust preventive package and stored for 1 month, from the bag, immediately under a nitrogen atmosphere without using flux, solder under the following conditions: It was immersed in a bath and the appearance of solder wet adhesion on the surface of the test piece was inspected. The results of the solder wet adhesion test are shown in Table 4.

[0033]

[Table 4] Solder wet adhesion before storage of test piece and after storage for 1 month ◯: The solder was evenly placed on and adhered to the surface of the test piece. ×: There are many parts where solder does not get on the surface of the test piece,
Attached in the form of bubbles.

With respect to the test piece plated with copper, the thickness of the oxide film on the metallic copper surface of the test piece was measured by the electrolytic reduction method by the following method. The measurement results are shown in Table 5. Oxidation amount analysis method Measuring principle: Electrolytic reduction method Measuring device: Harima Kasei Co., Ltd., Bodotester Measuring unit: The amount of electricity required to reduce copper oxide to metallic copper at a potential of −800 mV is calculated by the following formula: Cu ₂ O thickness Was converted into the amount of oxidation. _{δ = 71.5 · i p · t} / 96500.6 δ: oxide thickness (nm) i _p: current density (coulomb / second, cm ²⁾ t: Time (sec) Test piece: 10 × 60 × 0. 5 mm

[0035]

[Table 5] Oxide film thickness before and after storage for 1 month for test pieces plated with copper Note) Oxide film thickness: converted to Cu ₂ O

Comparative Example 1 The contents of the rust preventive package of Example 1 were changed to silica gel (A type) 3
Three types of test pieces plated with copper, silver and solder were stored in the same manner as in the example except that a desiccant package prepared in the same manner was used instead of g.

Comparative Example 2 Three kinds of test pieces plated with silver and solder were sealed in a storage bag of a silicon oxide vapor-deposited composite film together with 500 ml of nitrogen gas in the same manner as in Example without using a rust preventive package. . In this case, since the air in the storage bag was not completely replaced with nitrogen gas, the oxygen concentration in the bag when sealed was 0.7%. The storage bag in which these test pieces were sealed was stored in the same manner as in the example.

The test pieces stored in Comparative Example 1 and Comparative Example 2 were taken out from the bag, and were the same as in the Examples.
Solder adhesion was measured. Regarding the copper-plated test piece, the thickness of the oxide film on the copper surface was measured by the electrolytic reduction method. The results of Comparative Example 1 and Comparative Example 2 are shown in Table 1, Table 3, Table 4 and Table 5 in comparison with the results of Examples, respectively. In addition,
No reducing gas was detected in the storage systems of Comparative Example 1 and Comparative Example 2.

According to the method of the present invention, as shown in Table 4, the solder adhesion was good. Consider the reason why the solder adhesion of the method of the present invention is good. In the method of the present invention, as is clear from Tables 1 and 2, by sealing a material containing a metal member in a gas barrier container together with a rust preventive package, oxygen and water in the storage system are prevented from rusting. While being absorbed by the agent, the reducing substance is volatilized by the oxygen absorption reaction of the main agent of the rust preventive agent. Therefore, according to the method of the present invention, oxygen, water and corrosive substances are substantially absent, and the metal material is stored in a reducing atmosphere in which a reducing gas coexists, so that the solder bonding target It is considered that the formation of an oxide film on the metal surface is prevented, and further, the oxide is reduced to maintain good solder adhesiveness. The fact that reduction occurs on the oxide on the metal surface
For example, it has been confirmed that the charge of copper oxide is changed from divalent copper to monovalent copper on the metal copper surface of a copper-plated test piece.

[0040]

According to the method of the present invention, the material containing the metal member to be soldered is hermetically stored together with the rust preventive package in the gas barrier container to suppress the oxidation of the metal surface. Can maintain good solder adhesion,
Good solder bonding is possible without using flux. According to this method, particularly in the field of electronic materials, after solder bonding, there is no need for cleaning treatment with water containing an organic halogen-based solvent or a surfactant, and the cleaning process can be simplified and cost can be reduced. As a result, it is possible to eliminate the environmental pollution caused by the organic halogen-based solvent and contribute to the preservation of the global environment. That is, according to the method of the present invention, the material containing the metal member is oxygen,
It can be stored and transported without impairing the solder adhesiveness by keeping it in a reducing atmosphere in which water and a corrosive substance do not substantially exist and a reducing gas coexists.

[Brief description of drawings]

[Fig. 1] Time course of oxygen concentration in a rust preventive package hermetically sealed system (25 ° C)

[Fig. 2] Time-dependent changes in humidity of a rust preventive package hermetically sealed system (25 ° C)

[Fig. 3] Time-dependent change in hydrogen sulfide concentration in a rust preventive package sealed system (25 ° C)

Claims (3)

[Claims] 1. A metal member characterized in that a material containing a metal member is hermetically stored together with a rust preventive package in a container having a gas barrier property, and the material containing the metal member is soldered without using a flux. A method for soldering a material containing: 2. The solder bonding method for a material containing a metal member according to claim 1, wherein the material containing the metal member is an electronic material. 3. The material containing a metal member has an oxygen concentration of 0.5.
% Or less, and the method of solder bonding a material containing a metal member according to claim 1 or 2, which is a material containing a metal member stored in an atmosphere in which a reducing gas coexists.