JP6267427B2 - Soldering method and mounting board - Google Patents

Description

  The present invention relates to a solder material and a soldering material using the solder material. Specifically, a solder material that can be soldered at low cost and with high reliability to a substrate or electronic component having a solder layer having an electrode corrosion prevention layer formed on the electrode, and the solder material are used. It relates to the soldering method.

  In recent years, printed circuit boards, wafers, flexible boards, and the like (hereinafter also referred to as “mounting boards”) have been increasingly improved in wiring density and mounting density. The mounting board has many electrodes for soldering electronic components. Solder such as solder bumps and solder paste (hereinafter also referred to as “connection solder”) for soldering the electronic component is provided on the electrode, and the electronic component is soldered to the connection solder and mounted on the mounting board. To be implemented.

  The connecting solder is required to have high reliability in joining with an electronic component, high accuracy, and excellent durability. When such a solder joint is formed of an environment-friendly lead-free solder material, silver is usually contained as an indispensable component. A solder material containing silver is generally said to have improved solder wettability with respect to an electrode and can form a solder having excellent connection reliability with an electronic component.

  However, since silver is more expensive than zinc, tin, or the like, there is a problem that it is costly to mount electronic parts using a solder material containing silver. In addition, since silver has a high melting point, the solder material containing silver may further contain other expensive components such as bismuth and indium in order to lower the melting point, in which case there is a problem that the cost is further increased. . Therefore, there is a demand for a solder material for a substrate or electronic component that is lead-free and does not contain silver and can meet the above-described requirements.

  By the way, as a general method for forming connection solder, there is known a method of dipping (immersing) a mounting substrate provided with an electrode made of copper or the like (for example, a copper electrode; the same shall apply hereinafter) into molten solder as it is. When the solder contacts the copper electrode, copper and tin contained in the solder combine to form a CuSn intermetallic compound. The formation of this CuSn intermetallic compound itself is the basis of solder bonding. However, this phenomenon is sometimes referred to as “electrode corrosion” because the copper electrode is formed in such a manner that it is eroded by tin contained in the solder. Such electrode corrosion reduces the volume of the copper electrode that connects the electronic components, lowers the reliability, and may impair the reliability of the mounting board. Therefore, it is necessary to reduce the dipping time of the mounting board in the molten solder and suppress electrode corrosion. For this purpose, a preliminary solder layer is formed on the copper electrode of the mounting board, and then the mounting board is mounted. A method of dipping in molten solder (dipping method) has been studied.

Japanese Patent No. 5079169 Japanese Patent No. 5079170

  The present inventor has used a CuNiSn intermetallic compound layer on a copper electrode as an example of the embodiments of Patent Documents 1 and 2 so far, using a molten solder containing tin as a main component and at least nickel as a subcomponent. A technique for forming a solder layer having an electrode corrosion prevention layer made of has been proposed. According to this technique, since the molten solder essentially contains nickel, the nickel combines with the copper of the copper electrode, and further with the tin of the molten solder, a solder layer having a CuNiSn intermetallic compound layer is formed on the copper electrode. Easy to form. The CuNiSn intermetallic compound layer acts as a copper corrosion prevention layer for the copper electrode, and acts to prevent the copper electrode from being lost or lost. As a result, a solder layer having an electrode corrosion prevention layer made of a CuNiSn intermetallic compound layer can be used as a component in the solder layer even if the substrate on which the solder layer is mounted is heat-treated at a high temperature. There is an advantage that it is possible to suppress the corrosion.

  The present invention is a further advancement of the above technique, and its object is to provide a low-cost and high reliability for a substrate or electronic component having a solder layer having an electrode corrosion prevention layer formed on an electrode. It is to provide a solder material that can be soldered with the property. Another object of the present invention is to provide a soldering material using such a solder material.

  (1) A solder material according to the present invention for solving the above problems is a solder material provided for soldering a substrate or an electronic component, and the substrate or the electronic component has the substrate or the electronic component. A solder layer having the electrode corrosion prevention layer formed by combining a component contained in the electrode and a component that combines with the component to form an electrode corrosion prevention layer is formed on the electrode. The solder material does not contain a component that improves the solder wettability of the electrode.

  According to the present invention, since the solder material does not contain a component that improves the solder wettability of the electrode (also referred to as “solder wettability improving component”, for example, silver), the solder material can be soldered to a substrate or an electronic component at a low cost. Solder material can be provided. In addition, since the substrate or electronic component to be soldered with this solder material has a solder layer formed on the electrode, soldering can be performed even if the solder material does not contain a solder wettability improving component such as silver. At this time, the solder material spreads quickly on the electrode. As a result, a solder material having excellent connection reliability and capable of being soldered can be obtained. In addition, since the solder layer on the electrode has an electrode corrosion prevention layer, the electrodes of the substrate and the electronic component are protected by the electrode corrosion prevention layer even when heat-treated at a high temperature by a reflow furnace or the like when soldering. Erosion hardly occurs. As a result, a solder material with high reliability of the electrode after soldering can be obtained.

  It is preferable that the solder material according to the present invention does not include a component that forms the electrode corrosion preventing layer by combining with the component included in the electrode.

  According to this invention, since it does not include a component that forms an electrode corrosion prevention layer by combining with the component contained in the electrode, it occurs when the component of the electrode corrosion prevention layer and the component contained in the solder material are the same. It is possible to suppress the phenomenon of increasing the thickness of the electrode corrosion prevention layer. As a result, the reliability of the electrodes of the substrate or electronic component soldered with this solder material can be further improved.

  The solder material which concerns on this invention WHEREIN: It is preferable that the component which improves the solder wettability of the said electrode is silver, and the component which forms the said electrode corrosion prevention layer is nickel.

  In the solder material according to the present invention, it is preferable that the substrate is any one selected from a printed board, a wafer, and a flexible substrate, and the electronic component is any one selected from a chip, a resistor, a capacitor, and a filter.

  (2) A soldering method according to the present invention for solving the above problem is a soldering method using the solder material described in any one of the above, and on the electrode of the substrate or the electronic component, A substrate or electronic component on which a solder layer having the electrode corrosion prevention layer formed by combining a component contained in the electrode and a component that combines with the component to form an electrode corrosion prevention layer is formed. A step of preparing, a step of attaching a solder material that does not contain a component that improves the solder wettability of the electrode to the substrate or electronic component, and then heat-treating the substrate or electronic component to solder the solder material And a step of attaching.

  According to this invention, since the solder material does not contain a component that improves the solder wettability of the electrode, the substrate or the electronic component can be soldered at a low cost. Moreover, since the board | substrate or electronic component which has a solder layer on an electrode is prepared, a solder material spreads quickly on an electrode. As a result, soldering with excellent connection reliability is possible. In addition, since the solder layer has an electrode corrosion prevention layer, even if heat treatment is performed at a high temperature in a reflow furnace or the like in the heat treatment step, the electrode of the substrate or electronic component is protected by the electrode corrosion prevention layer. , Erosion can be suppressed. As a result, the reliability of the electrode after soldering can be ensured.

  In the soldering method according to the present invention, it is preferable that the solder material does not include a component that forms an electrode corrosion prevention layer by combining with the component included in the electrode.

  According to the present invention, since the solder material does not include a component that forms an electrode corrosion prevention layer by combining with a component contained in the electrode, the formed solder includes a component that forms the electrode corrosion prevention layer. Absent. As a result, it is possible to suppress the thickness expansion phenomenon of the electrode corrosion prevention layer that may occur when the components of the electrode corrosion prevention layer and the components contained in the solder are the same, and the reliability of the electrode after soldering It can be set as the soldering method which can improve further.

  In the soldering method according to the present invention, it is preferable that the component that improves the solder wettability of the electrode is silver, and the component that forms the electrode corrosion preventing layer is nickel.

  According to the solder material and the soldering method of the present invention, low-cost and high-reliability soldering is performed on a substrate or an electronic component in which a solder layer having an electrode corrosion prevention layer is formed on the electrode. The solder material which can be provided, and the soldering material using the solder material can be provided.

It is sectional drawing which shows an example of the board | substrate soldered with the solder material which concerns on this invention. It is sectional drawing which shows an example of the electronic component soldered with the solder material which concerns on this invention. It is process drawing which shows an example of the method of soldering a board | substrate and an electronic component with the solder material which concerns on this invention. It is sectional drawing of the electrode heat-processed after making the solder material which concerns on this invention adhere on the electrode corrosion prevention layer of an electrode.

  Hereinafter, a solder material and a soldering method according to the present invention will be described with reference to the drawings. In addition, this invention is not limited to embodiment shown concretely below. Further, the “electrode corrosion prevention layer” functions so as to suppress a part or all of the components constituting the electrode from being eroded by solder (an aspect in which the electrode components are diffused and dissolved). It is a layer.

[Solder material]
As shown in FIGS. 1 to 3, the solder material 5 according to the present invention is a solder material 5 provided for soldering the substrate 10 or the electronic component 20. As shown in FIGS. 1 and 2, the substrate 10 or the electronic component 20 is formed on the electrode 2 of the substrate 10 or the electronic component 20, and the components contained in the electrode 2 are combined with the components to prevent electrode corrosion. A solder layer 4 having an electrode corrosion preventing layer 3 formed by combining with the components forming the layer 3 is formed.

  The solder material 5 according to the present invention is characterized in that it does not contain a component that improves the solder wettability of the electrode 2. Since the component which improves the solder wettability of the electrode 2 is expensive as represented by silver or the like, for example, the material cost of soldering becomes high. In this invention, since the component which improves the solder wettability of such an electrode 2 is not included, the board | substrate 10 and the electronic component 20 can be soldered at low cost.

  Further, since the solder layer 4 (also referred to as a first solder layer) is formed on the electrode 2 of the substrate 10 or the electronic component 20, the solder layer 4 acts as a preliminary solder, and the solder material 5 It quickly wets and spreads on the electrode 2 having the solder layer 4. As a result, the solder material 5 that does not contain a component that improves the solder wettability of the electrode 2 and can be soldered with excellent connection reliability can be obtained. Furthermore, since the solder layer 4 has the electrode corrosion prevention layer 3, even if heat treatment is performed at a high temperature by a reflow furnace or the like when soldering, the electrode 2 does not cause corrosion and high-reliability soldering is achieved. Possible solder material 5 can be obtained.

  Hereinafter, each configuration will be described in detail.

(Solder material)
The solder material 5 does not need to include a component that improves the solder wettability of the electrode 2, and various solder compositions can be used. The component that improves the solder wettability of the electrode 2 is, for example, silver when the electrode 2 is a copper electrode, and various components that improve the wettability of the electrode 2 in the case of the electrode 2 of another material. . Moreover, it is preferable that the solder material 5 does not contain the same component as the component of the electrode corrosion prevention layer 4 which the solder layer formed in the surface of the electrode 2 has. Such a solder material 5 can suppress the phenomenon of increasing the thickness of the electrode corrosion prevention layer 3 that may occur when the components of the electrode corrosion prevention layer 3 and the components contained in the solder material 5 are the same. The reliability of the electrode after attachment can be further improved. Examples of the component that causes the electrode corrosion preventing ability include nickel.

  The solder material 5 is, for example, a quaternary, ternary, or ternary solder that does not contain nickel, or a quaternary, quaternary, or ternary solder that contains nickel. Alternatively, bismuth-based low temperature solder may be used. As the solder material 5, for example, lead-free solder containing tin as a main component and optionally containing one or more selected from copper, zinc, bismuth, antimony and germanium as subcomponents is preferably used. Since the solder material 5 is a lead-free solder material that does not contain silver, the substrate 10 or the electronic component 20 can be soldered at low cost while considering the environment.

  As the solder material 5 that does not contain silver or nickel, SnCu solder, SnGe solder, SnP solder, SnCuGe solder, SnCuGeP solder, SnZnAl solder, SnSb solder, or the like can be used. Moreover, examples of the low melting point solder containing neither silver nor nickel include SnBi solder and SnBiZn solder. Moreover, as a thing which does not contain silver but contains nickel, it is possible to use SnNi solder, SnCuNi solder, SnGeNi solder, SnPNi solder, SnCuGeNi solder, SnCuGePNi solder, SnZnAlNi solder, SnSbNi solder, etc. it can. In addition, examples of the low melting point solder that does not contain silver and contains nickel include SnBiNi solder, SnBiZnNi solder, and the like.

  The solder material 5 may be a paste solder or a meltable metal solder as long as it is a solder material that melts within a range of 150 ° C. or more and 300 ° C. or less. Among them, the paste solder is conveniently used, and is a solder paste (also referred to as a solder paste) containing tin as a main component and optionally containing one or more selected from copper, zinc, bismuth, antimony and germanium as subcomponents. ) Is preferably used. The solder paste is a paste-like composite material of solder powder and flux, and is used in the printing process as a bonding material in a method (SMT) of soldering electronic components by surface mounting. The flux is not particularly limited, and a flux in which various types are arbitrarily mixed can be used.

(Board or electronic component)
The substrate 10 or the electronic component 20 is a component to be soldered with the solder material 5 described above. The board | substrate 10 or the electronic component 20 has the 1 or 2 or more electrode 2 on the base material 1, as shown in FIG.1 and FIG.2. On the surface of the electrode 2, an electrode corrosion prevention layer 3 formed by combining a component included in the electrode 2 and a component that combines with the component included in the electrode 2 to form the electrode corrosion prevention layer 3 is formed. A solder layer 4 is formed. Note that an organic fatty acid coating film for preventing oxidation and contamination of the solder layer 4 may be formed on the solder layer 4 of the substrate 10 or the electronic component 20.

  Examples of the substrate 10 include a printed board, a wafer, and a flexible board in which the electrode 2 is provided on the base material 1 in any form and number. Electronic components 20 include connectors, QFP (Quad Flat Package), SOP (Small Out Line Package), BGA (Ball Grid Array), LGA (Land Grid Array), semiconductor chips, chip resistors, chip capacitors, jumper wiring materials, etc. Can be mentioned.

  The type, size, and form of the electrode 2 are not particularly limited, but a metal component that forms an intermetallic compound layer by combining with tin contained in molten solder for forming the solder layer 4 formed thereon is formed. Including conductive electrodes. Examples of the metal component that forms an intermetallic compound layer by combining with tin include Cu, Ag, Au, Pd, Rh, Zn, Sn, Ni, Co, and Bi. The electrode 2 is comprised by 1 type, or 2 or more types chosen from such a metal component. Specific examples of the electrode 2 include a copper electrode, a copper alloy electrode, a silver electrode, a silver alloy electrode, a gold electrode, a gold alloy electrode, a palladium electrode, a palladium alloy electrode, an aluminum electrode, and an aluminum alloy electrode.

  The electrode corrosion prevention layer 3 is a layer that the solder layer 4 described later has, and a component included in the electrode 2 and a component that combines with the component included in the electrode 2 to form the electrode corrosion prevention layer 3. It is a layer formed on the surface of the electrode 2 by combining. Such an electrode corrosion preventing layer 3 is made of an intermetallic compound, and is particularly preferably a layer made of a nickel-containing intermetallic compound. Examples of the nickel-containing intermetallic compound include an intermetallic compound layer made of CuNiSn alloy, AgNiSn alloy, AuNiSn alloy, PdNiSn alloy, RhNiSn alloy, ZnNiSn alloy, SnNiSn alloy, NiNiSn alloy, CoNiSn alloy, BiNiSn alloy, and the like. it can. The electrode corrosion prevention layer 3 made of such a nickel-containing intermetallic compound is composed of molten solder for forming the solder layer 4 and tin contained in the solder material 5 used thereafter compounded with the constituent components (for example, Cu) of the electrode 2. In this way, the electrode is prevented from being lost or lost. As a result, the solder layer 4 having the electrode corrosion prevention layer 3 made of a nickel-containing intermetallic compound can be used to cause the electrode 2 to remain in the solder layer 4 even if the substrate having the solder layer 4 is heat-treated at a high temperature. It can suppress being eroded by a component.

  The thickness of the electrode corrosion preventing layer 3 is preferably 0.5 μm or more and 3 μm or less. In order to stabilize the electrode corrosion preventing ability of the electrode corrosion preventing layer 3, it is preferable that the electrode corrosion preventing layer 3 is formed with a uniform thickness while suppressing defects and the like. By setting the thickness of the electrode erosion layer 3 within the above range, the component (for example, Sn) included in the solder layer 4 provided on the electrode 2 is combined with the electrode component (for example, Cu) and eroded. Can be suppressed. If the electrode corrosion preventing layer 3 is too thick, the electrode corrosion preventing layer 3 itself may be cracked or cracked. Therefore, the thickness of the thickest part is preferably 3 μm or less. In particular, the thinnest part of the electrode corrosion preventing layer 3 is 0.5 μm or more and the thickest part is 3 μm or less, and the total average thickness of the electrode corrosion preventing layer 3 is particularly 1 μm or more and 2 μm or less. preferable. Note that the thickness was calculated from the result of 100 points measured from the result of observing the cross section with a scanning electron microscope or a transmission electron microscope.

  The solder layer 4 (first solder layer) is a layer formed on the electrode 2 and acts as a preliminary solder when soldering using the solder material 5. Since such a solder layer 4 is formed, the solder material 5 wets and spreads on the electrode 2, and the solder material 5 that can be soldered with excellent connection reliability can be obtained.

  The solder layer 4 is a molten solder containing a component (for example, nickel) that forms an electrode corrosion prevention layer made of an intermetallic compound by combining with the component contained in the electrode 2 on the electrode 2 of the substrate 10 or the electronic component 20. It is formed by bringing the molten solder into contact with the electrode 2 and then removing excess molten solder.

  Specifically, for example, the copper electrode 2 is brought into contact with a molten solder containing tin and nickel, and the molten solder is attached on the copper electrode 2. As for the method of attaching, the substrate 10 or the electronic component 20 may be immersed in the molten solder as in the examples described later, or printed on the solder layer 4 of the electrode 2 and then heated and melted. Then, molten solder may be deposited on the electrode 2. Nickel contained in the adhered molten solder is combined with copper of the copper electrode 2 and further combined with tin contained in the molten solder, so that a CuNiSn intermetallic compound layer is easily formed on the surface of the electrode 2. Thereafter, an excess of molten solder is removed by jetting an air flow or a liquid flow toward the adhered molten solder. As a result, the electrode corrosion preventing layer 3 is provided on the electrode 2, and the thin solder layer 4 is provided on the electrode corrosion preventing layer 3.

  As the molten solder, when the electrode 2 is a copper electrode or a copper alloy electrode, a molten lead-free solder containing tin as a main component and at least nickel as a subcomponent is preferably used. A low melting point molten solder containing at least nickel as an auxiliary component in a tin bismuth solder is also preferably used. Such molten lead-free solder may further optionally contain one or more selected from copper, germanium and phosphorus as subcomponents. Moreover, the silver said to improve wettability further may be contained. Note that the surface of the electrode 2 may be cleaned by bringing the organic fatty acid-containing solution into contact with the electrode 2 before contacting the molten solder. Since the wettability of the electrode 2 is improved by cleaning the surface of the electrode 2 in advance, in that case, the molten solder does not need to contain expensive silver.

[Soldering method]
The soldering method according to the present invention is a soldering method using the solder material 5 described above, and is included in the electrode 2 on the electrode 2 of the substrate 10 or the electronic component 20 as shown in FIG. The substrate 10 or the electronic component 20 on which the solder layer 4 having the electrode corrosion preventing layer 3 formed by combining the component to be combined with the component forming the electrode corrosion preventing layer 3 is combined. A step of preparing (FIG. 3A), a step of attaching a solder material 5 not containing a component that improves the solder wettability of the electrode 2 to the substrate 10 or the electronic component 20 (FIGS. 3B and C), and then the substrate 10 or The electronic component 20 is heated to solder the solder material 5 to form the second solder layer 6 (FIG. 3D). The present invention is characterized in that the solder material does not contain a component that improves the solder wettability of the electrode 2.

  Since the solder material 5, the substrate 10, the electronic component 20, the electrode corrosion prevention layer 3 and the solder layer 4 are as described above, description thereof is omitted here. The method for attaching the solder material 5 to the solder layer 4 is not particularly limited. For example, the paste-like solder material 5 can be applied to the solder layer 4 by any method using a mesh or the like on which a predetermined pattern is formed. A method of attaching by printing or a method of attaching a molten solder of the metallic solder material 5 on the solder layer 4 can be exemplified.

  The method for the heat treatment is not particularly limited, and for example, the heat treatment can be performed by heating to a melting point or higher of the solder material in a reflow furnace or the like. In this soldering method, since the solder layer 4 having the electrode corrosion preventing layer 3 is formed in advance on the electrode 2 of the substrate 10 and the electronic component 20, the electrode corrosion in each part of the electrode 2 is also performed by such heat treatment. The reliability of the electrode 2 can be maintained.

  Hereinafter, the present invention will be described in more detail with reference to examples. Note that the present invention is not limited thereby.

[Example 1]
In Example 1, the first solder layer was formed of a SnNiCuGe quaternary solder material, and the second solder layer was formed of a SnCu binary solder material.

(Board or electronic component)
As an example, a substrate 10 was prepared in which a copper wiring pattern having a width W of 50 μm and a thickness of 20 μm was formed on a printed board 1 having a length of 100 mm × width of 100 mm (see, for example, FIG. 1). A first organic fatty acid-containing solution having the following composition was sprayed onto the copper electrode 2 and coated to provide an organic fatty acid coating film (not shown) on the copper electrode 2. This organic fatty acid coating film is deposited as a result of cleaning the copper surface with the first organic fatty acid-containing solution. As the first organic fatty acid-containing solution, an organic fatty acid-containing solution containing palmitic acid in an ester synthetic oil not containing a metal salt such as a nickel salt or a cobalt salt or an antioxidant so as to be 10% by mass. Using. The temperature of the first organic fatty acid-containing solution was controlled at 150 ° C.

  Subsequently, a liquid flow (250 ° C.) of molten solder A having the following composition was sprayed toward the coated substrate 10. On the copper electrode 2 to which the molten solder was sprayed, the molten solder adhered and was piled up. The molten solder used was a quaternary lead-free solder (melting point: about 227 ° C.) consisting of Ni: 0.05 mass%, Ge: 0.005 mass%, Cu: 0.7 mass%, and the balance being Sn. The solder was purified by vigorous stirring under the condition of 250 ° C. with the same organic fatty acid-containing solution as the first organic fatty acid-containing solution. The viscosity of the molten solder 5a was 0.0035 Pa · s at 250 ° C.

  Subsequently, excess molten solder accumulated on the copper electrode 2 was removed. The removing means used was an injection nozzle, from which the second organic fatty acid-containing solution having the same composition as the first organic fatty acid-containing solution was heated to 250 ° C. and injected. After the molten solder is sprayed onto the copper electrode 2, the excess solder is removed with the second organic fatty acid-containing solution, and then an air stream is sprayed onto the component to rapidly cool the first molten solder to 200 ° C., which is below its melting point. The total time to complete was 10 seconds. As a result, a substrate 10 having the form shown in FIG. 1 was obtained. The substrate 10 is provided on the copper electrode 2 in the order of an electrode corrosion prevention layer 3, a solder layer 4 (solder layer remaining after removal), and a coating film (not shown).

  Thus, the substrate 10 on which the solder layer 4 having the electrode corrosion preventing layer 3 was formed was prepared. When the cross section was observed with an electron microscope, an electrode corrosion prevention layer 3 having a thickness of about 1.5 μm and no cracks was provided on the copper electrode 2 of the substrate 10. The thickness T was about 2.5 μm. The solder layer 4 was attached, and it was confirmed that the coating film was thinly attached on the solder layer 4. Thus, the board | substrate 10 with which the solder layer 4 was formed with good wettability is prepared even if it does not contain silver by using the molten solder which cleaned the copper surface with the organic fatty acid containing solution, and refine | purified with the organic fatty acid containing solution. can do. By preparing such a substrate 10, it becomes unnecessary to use silver from the preparation stage of the substrate 10. As a result, the solder material 5 that can be soldered at a lower cost can be applied to the substrate 10 thus prepared.

(Soldering)
On the copper electrode 2 of the substrate 10 thus obtained, the solder material 5 was attached by screen printing (FIG. 3B). As the solder material 5 according to Example 1, binary lead-free solder (melting point: about 227 ° C.) composed of Cu: 3.0% by mass and the balance being Sn was used.

  Subsequently, the electronic component 20 was placed on the solder material 5 so that the copper electrode 2 of the electronic component 20 was in contact (FIG. 3C), and then heated for 10 minutes in a reflow furnace set at 250 ° C. Thus, the board | substrate 10 and the electronic component 20 were soldered using the solder material 5 which concerns on Example 1 (FIG. 3D). There were no defects or voids in the soldered part. Moreover, when the cross section was observed with the electron microscope, as shown in FIG.4 (B), the corrosion of the electrode 2 was suppressed as much as possible, and it did not change so much with the original thing shown in FIG.4 (A). . The thickness of the electrode corrosion preventing layer 3 was almost the same as that of the substrate 10 before soldering. These production conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[Example 2]
In Example 2, the first solder layer was formed of a SnNiCuGe quaternary solder material, and the second solder layer was formed of a SnNiCu ternary solder material.

  Instead of the solder material 5 of Example 1, the solder material 5 according to Example 2 is a ternary lead-free solder (melting point: Ni: 0.5% by mass, Cu: 3.0% by mass, the balance being Sn) : About 228 ° C.), the substrate 10 and the electronic component 20 were soldered in the same manner as in Example 1. There were no defects or voids in the soldered part. Moreover, when the cross section was observed with an electron microscope, the electrode corrosion preventing layer 3 was slightly thicker than the substrate 10 before soldering, but the electrode 2 corrosion was suppressed as much as in Example 1. It was not much different from the original one.

[Example 3]
In Example 3, the first solder layer was formed of a SnAgNiCuGe ternary solder material, and the second solder layer was formed of a SnCu binary solder material.

  A substrate 10 was prepared in the same manner as in Example 1 except that the following substrate 10 was used in place of the substrate 10 in Example 1. That is, in Example 1, the substrate 10 is not subjected to the coating treatment with the first organic fatty acid and the purification treatment of the molten solder, and in addition to using the molten solder having the following composition instead of the molten solder 5, A substrate 10 was prepared in the same manner as the substrate 10 used in Example 1. The molten solder used here is Ni: 0.05% by mass, Ge: 0.005% by mass, Ag: 3% by mass, Cu: 0.5% by mass, and the remainder being Sn-based pent system lead-free solder ( Melting point: about 217 ° C.). When the cross section of the substrate 10 was observed with an electron microscope, the thickness T of the electrode corrosion preventing layer 3 having a thickness of about 1.5 μm and no cracks was formed on the copper electrode 2 of the substrate 10 of about 2.5 μm. The solder layer 4 was attached, and it was confirmed that the coating film was thinly attached on the solder layer 4.

  Subsequently, similarly to Example 1, the substrate 10 and the electronic component 20 were soldered. There were no defects or voids in the soldered part. Moreover, when the cross section was observed with the electron microscope, the corrosion of the electrode 2 was suppressed as much as possible like Example 1, and it did not change so much from the initial one.

[Example 4]
In Example 4, the first solder layer was formed of a SnAgNiCuGe ternary solder material, and the second solder layer was formed of a SnNiCu ternary solder material.

  In Example 1, the substrate 10 prepared in Example 3 was used, and the substrate 10 and the electronic component 20 were soldered in the same manner as in Example 1 except that the solder material 5 according to Example 2 was used. . There were no defects or voids in the soldered part. Moreover, when the cross section was observed with the electron microscope, although the electrode corrosion prevention layer 3 was a little thicker than Example 1, as with Example 1, the corrosion of the electrode 2 was suppressed as much as possible. It wasn't much different from the ones.

[Comparative Example 1]
In Comparative Example 1, the first solder layer was formed of a SnNiCuGe quaternary solder material, and the second solder layer was formed of a SnAgNiCuGe quaternary solder material.

  In Example 1, instead of the solder material 5, the solder material according to Comparative Example 1 is Ni: 0.05 mass%, Ge: 0.005 mass%, Ag: 3 mass%, Cu: 0.5 mass%. The substrate 10 and the electronic component 20 were soldered in the same manner as in Example 1 except that a ternary lead-free solder (melting point: about 217 ° C.) consisting of Sn was used as the balance. There were no defects or voids in the soldered part. Moreover, when the cross section is observed with an electron microscope, as in Example 1, although the corrosion of the electrode 2 is suppressed as much as possible, the material cost is high because the solder material contains silver.

[Comparative Example 2]
In Comparative Example 2, the first solder layer was formed of a SnAgCu ternary solder material, and the second solder layer was formed of a SnCu binary solder material.

  In Example 1, the substrate 10 was prepared in the same manner as in Example 1 except that the following substrate 10 was used instead of the substrate 10. That is, in Example 1, the substrate 10 is not subjected to the coating treatment with the first organic fatty acid and the purification treatment of the molten solder, and in addition to using the molten solder having the following composition instead of the molten solder 5, A substrate 10 was prepared in the same manner as the substrate 10 used in Example 1. As the molten solder, ternary lead-free solder (melting point: about 216 ° C.) composed of Cu: 6% by mass, Ag: 2% by mass, and the balance being Sn was used. When the cross section of the substrate 10 was observed with an electron microscope, the electrode corrosion preventing layer 3 was not formed on the copper electrode 2 of the substrate 10, and only a solder layer having a thickness of about 1 μm was adhered. It was confirmed.

  Subsequently, in the same manner as in Example 1, the substrate 10 and the electronic component 20 were soldered using the solder material 5. There were no defects or voids in the soldered part. Moreover, when the cross section was observed with the electron microscope, it was confirmed that the electrode was eroded and thinner than the original one. Therefore, when the solder layer formed on the electrode of the prepared substrate does not have the electrode corrosion prevention layer, it is difficult to ensure the reliability of the electrode after soldering.

[Comparative Example 3]
In Comparative Example 3, the first solder layer was not provided, and the second solder layer was formed of a SnAgNiCuGe ternary solder material.

  In Example 1, instead of the substrate 10, the substrate 10 is used as it is (that is, in a state where the coating process using the organic fatty acid is not performed and the solder layer 4 is not formed), and the solder material 5 is used. The board | substrate 10 and the electronic component 20 were soldered similarly to Example 1 except having used the solder material which concerns on the above-mentioned comparative example 1. FIG. There were no defects or voids in the soldered part. Moreover, when the cross section is observed with an electron microscope, as in Example 1, although the corrosion of the electrode 2 is suppressed as much as possible, the material cost is high because the solder material contains silver.

[Comparative Example 4]
In Comparative Example 4, the first solder layer was not provided, and the second solder layer was formed of a SnAgCu ternary solder material.

  In Example 1, in place of the substrate 10, the substrate 10 is used as it is (that is, in a state where a coating process using an organic fatty acid is not performed and a solder layer is not formed), and the solder material 5 is used. The board | substrate 10 and the electronic component 20 were soldered similarly to Example 1 except having used the solder material which has the composition of these. As the solder material, ternary lead-free solder (melting point: about 216 ° C.) composed of Cu: 6% by mass, Ag: 2% by mass, and the balance being Sn was used. There were no defects or voids in the soldered part. Moreover, when the cross section was observed with the electron microscope, it was confirmed that the electrode was eroded and thinner than the original one. Therefore, it is difficult for the solder material according to Comparative Example 4 to ensure the reliability of the electrode after soldering. Moreover, since silver is included, material cost is high.

  As described above, according to the solder material and the soldering method according to the present invention, the solder material and the soldering method using the solder material that can solder the substrate or the electronic component having the solder layer on the electrode with low cost and high reliability are provided. Can be provided.

DESCRIPTION OF SYMBOLS 1 Base material 2 Electrode 3 Electrode corrosion prevention layer 4 Solder layer (1st solder layer)
5 Solder material 6 Second solder layer 10 Substrate 20 Electronic component

Claims (6)

A method of soldering electronic components to a board,
Cleaning the electrode surface of the substrate and the electronic component with an organic fatty acid-containing solution, and providing the organic fatty acid coating film on the electrode;
The electrode provided with the coating film is a molten lead-free solder containing tin as a main component, nickel as a subcomponent, and not containing silver, and purified by stirring in a molten state in the same organic fatty acid-containing solution as described above. A substrate on which a solder layer having the electrode corrosion prevention layer is formed by combining the component contained in the electrode and the component that combines with the component to form an electrode corrosion prevention layer by bringing them into contact with each other And a step of preparing an electronic component;
Attaching a solder material not containing silver, which is a component that improves solder wettability of the electrode, to the substrate on which the solder layer is formed;
And a step of heat-treating the electronic component on which the solder material is adhered and the electronic component on which the solder layer is formed to solder the electronic component to the substrate. Said solder material, nickel contains no is a component which combine to components included in the electrode forming the electrode corrosion prevention layer, a soldering method according to claim 1.   The soldering method according to claim 1, wherein the substrate is any one selected from a printed circuit board, a wafer, and a flexible substrate, and the electronic component is any one selected from a chip, a resistor, a capacitor, and a filter. . A mounting board in which electronic components are soldered to a board,
The electrode surface of the substrate and the electronic component is cleaned with an organic fatty acid-containing solution, and the organic fatty acid coating film is formed on the electrode.
The electrode provided with the coating film is a molten lead-free solder containing tin as a main component, nickel as a subcomponent, and not containing silver, and purified by stirring in a molten state in the same organic fatty acid-containing solution as described above. The component contained in the electrode and the component that combines with the component to form the electrode corrosion prevention layer are combined to form a solder layer having the electrode corrosion prevention layer,
The substrate on which the solder layer is formed and the electronic component on which the solder layer is formed are soldered with a solder material that does not contain silver, which is a component that improves the solder wettability of the electrode. Mounting board.   The mounting board according to claim 4, wherein the solder material does not contain nickel, which is a component that forms the electrode corrosion prevention layer by combining with a component contained in the electrode. The mounting substrate according to claim 4 or 5, wherein the substrate is any one selected from a printed circuit board, a wafer, and a flexible substrate, and the electronic component is any one selected from a chip, a resistor, a capacitor, and a filter.