WO2016098836A1 - Coated solder wire and method for manufacturing same - Google Patents

Abstract

The present invention provides a manufacturing method by which a coated solder wire having a dense coating film of polysiloxane uniformly provided over the entire surface of the solder wire can be obtained efficiently, through a single process. This method for manufacturing a coated solder wire comprises a radicalization step for mixing a reactant gas transformed into a plasma at atmospheric pressure, and an organosilicon compound introduced through the agency of carrier gas, and radicalizing the organosilicon compound to form a radicalized organosilicon compound; a reaction area formation step for forming a reaction area which is demarcated by a spiral gas flow and in which the radicalized organosilicon compound is uniformly dispersed; and a coating step for transporting the solder wire into the reaction area, and reacting the metal at the solder wire surface with the radicalized organosilicon compound, thereby forming a coating film of polysiloxane having a thickness of 4-200 nm on the solder wire surface.

Description

Coated solder wire and manufacturing method thereof

The present invention relates to a solder wire used in manufacturing a semiconductor device and a manufacturing method thereof.

In the manufacture of semiconductor element bonding substrates and semiconductor devices, soldering is generally employed when bonding metal materials together or when bonding electronic components such as semiconductor elements to a printed circuit board. Solder materials used for soldering are formed into various shapes such as wires, ribbons, sheets, preform materials (punching materials), balls, and fine powders.

Solder material is easily oxidized in the presence of oxygen, and an oxide film is formed on the surface during storage. In particular, when the solder material is used after a long period of time since it is manufactured, the oxidation proceeds and the oxide film becomes thick. This causes joint defects such as voids. In addition, since the solder material is melted at a high temperature during use, the oxide film becomes thicker. If the thick oxide film formed in this way is present at the bonding interface, problems such as poor continuity and poor bonding are caused.

As a technique for preventing oxidation of metal materials and alloy materials, a method of forming a coating film by surface treatment is known. In particular, the surface treatment using the atmospheric pressure plasma CVD method can form a dense coating film at a relatively low cost, so that not only the antioxidant effect is high but also the film forming material diffuses into the room. It has attracted attention because of its superior safety.

For example, in Japanese translation of PCT publication No. 2004-510571, a spray liquid coating forming material composed of an organosilicon compound is introduced into an atmospheric pressure plasma discharge, and a substrate such as a metal is exposed to the spray coating forming material (coating material). A method of forming a coating (coating film) made of polydimethylsiloxane or the like on the surface of a substrate is disclosed.

However, in the technique described in this document, after the reaction gas, the carrier gas, and the coating material are supplied into the apparatus, the reaction gas is turned into plasma and activated (radicalization) of the coating material that is atomized. Since they are performed simultaneously, the activation of the coating material becomes non-uniform, and it is difficult to form a dense coating film uniformly over the entire surface of the substrate. In addition, the technique described in this document is not intended to prevent the oxidation of the surface of the solder material, but the behavior of the coating film when the solder material melts, the wettability due to the presence of the coating film, and bonding. No consideration is given to the effect on sex.

On the other hand, Japanese Patent Application Laid-Open No. 2014-195831 discloses radicalization of an organosilicon compound by mixing and spraying an organosilicon compound together with a carrier gas in a plasma gas under atmospheric pressure. A method for producing a coated solder material is disclosed in which a coating film made of polysiloxane having a thickness of 4 nm to 200 nm is formed by reacting with a metal present on the surface of the solder material while polymerizing the compound. According to this method, since the organosilicon compound can be radicalized instantly, a dense coating film can be uniformly formed over the entire surface of the solder material while maintaining the basic skeleton of the organosilicon compound. it can. For this reason, it becomes possible to prevent the progress of oxidation during long-term storage and melting without impairing the wetting and joining properties of the solder material.

Japanese translation of PCT publication No. 2004-510571 JP 2014-195831 A

By the way, when the entire surface of a long solder wire is coated by the technique described in Japanese Patent Application Laid-Open No. 2014-195831, as shown in FIG. In the example, it is necessary to perform processing three times. That is,
(1) While conveying the solder wire 2 in the direction of arrow A while fixing the conveying jig 7 capable of preventing the twist of the solder wire 2 during conveyance so that the surface 7a is on the bottom surface side, from the nozzle 8 The radicalized organosilicon compound 5 is sprayed to form a coating film 3a (see FIG. 2 (a-1)),
Next, (2) the transfer jig 7 is rotated 120 ° so that the surface 7b is on the bottom surface side, and then the coating film 3b is formed in the same manner as in the step (1) (FIG. 2 (b-1)). )reference),
Finally, (3) the transport jig 7 is further rotated by 120 ° so that the surface 7c is on the bottom side, and then the coating film 3c is formed in the same manner as in the steps (1) and (2) ( Fig. 2 (c-1))
It will be necessary.

For this reason, when the technique described in Japanese Patent Application Laid-Open No. 2014-195831 is applied as it is to manufacturing on an industrial scale, the productivity of the coated solder wire is expected to be significantly impaired. Further, as shown in FIGS. 2 (a-2), 2 (b-2), and 2 (c-2), a thin coating portion is formed at the boundary between the coating films 3a to 3c. There is room for improvement in the uniformity of the thickness of the entire coating film.

In view of these problems, an object of the present invention is to provide a coated solder wire in which a dense coating film made of polysiloxane is uniformly provided over the entire surface of the solder wire. Moreover, an object of this invention is to provide the method of manufacturing such a coated solder wire efficiently by one process.

The coated solder wire of the present invention is a coated solder wire composed of a solder wire and a coating film made of polysiloxane provided on the surface of the solder wire, and the coating film has a thickness of 4 nm. 200 nm, the difference between the maximum value and the minimum value of the thickness is within 2.5 nm, and the ratio of the coating film to the entire coated solder wire is 200 mass ppm or less in terms of silicon. And

The solder wire contains 80% by mass or more of Pb and one or more second elements selected from the group consisting of Sn, Ag, Cu, In, Te, and P, and Pb and second A solder wire made of a solder alloy having a total content of 95% by mass or more with elements can be suitably used. Alternatively, 80% by mass or more of Sn and one or more second elements selected from the group consisting of Ag, Sb, Cu, Ni, Ge, and P, and Sn and the second element A solder wire made of a solder alloy having a total content of 95% by mass or more can be suitably used.

The method for producing the coated solder wire of the present invention is as follows.
Radicalization that forms a radicalized organosilicon compound by mixing the reaction gas plasmatized at atmospheric pressure with an organosilicon compound introduced via a carrier gas and radicalizing the organosilicon compound Process,
A reaction zone forming step defined by a spiral gas flow to form a reaction zone in which the radicalized organosilicon compound is uniformly dispersed;
A coating made of polysiloxane having a thickness of 4 nm to 200 nm on the surface of the solder wire by transporting the solder wire in the reaction region and reacting the radicalized organosilicon compound with the metal on the surface of the solder wire. A coating process for forming a film;
It is characterized by providing.

In the reaction region forming step, it is preferable to form the reaction region by mixing the radicalized organosilicon compound into a spiral gas flow introduced in advance. In this case, the spiral gas flow can be formed by at least one selected from the group consisting of argon, helium, nitrogen, oxygen, and air.

As the organosilicon compound, at least one organic substituent selected from the group consisting of alkyl group, alkoxy group, fluoroalkyl group, amino group, epoxy group, isocyanate group, mercapto group, vinyl group, methacryloxy group, and acryloxy group It is preferable to use an organosilicon compound having

As the reaction gas, at least one selected from the group consisting of argon, helium, nitrogen, oxygen, and air can be used. Further, as the carrier gas, at least one selected from argon, helium, and nitrogen can be used.

In the radicalization step, the organosilicon compound is preferably radicalized by an atmospheric pressure plasma polymerization treatment apparatus.

In the radicalization step, the amount of the organosilicon compound introduced into 1 m of the solder wire is preferably 0.006 g to 0.300 g. In addition, it is preferable that the conveying speed of the solder wire in the coating step is 1 m / min to 100 m / min.

According to the present invention, it is possible to provide a coated solder wire in which a dense coating film made of polysiloxane is uniformly provided over the entire surface of the solder wire. Moreover, according to this invention, the method which can manufacture such a covering solder wire efficiently by one process can be provided. For this reason, the industrial significance of the present invention is extremely large.

FIG. 1A is a schematic perspective view for explaining a method of manufacturing a coated solder wire according to the present invention, and FIG. 1B is a cross-sectional view of the coated solder wire obtained by this manufacturing method. is there. 2 (a-1) to 2 (c-1) are schematic perspective views for explaining a conventional method for manufacturing a coated solder wire, and FIGS. 2 (a-2) to 2 (c-2) FIG. 3 is a cross-sectional view of a coated solder wire at each stage. 3A to 3D are cross-sectional TEM photographs of the coated solder wire obtained in Example 2. FIG. 4A and 4B are cross-sectional TEM photographs of the coated solder wire obtained in Comparative Example 3. FIG.

As a result of repeated investigations on the above-described problems, the present inventors have previously obtained a reaction region in which radicalized organosilicon compounds are uniformly dispersed and the radicalized organosilicon compounds can react with the metal on the surface of the solder wire. It was found that an extremely uniform and dense coating film can be formed by a single treatment by forming a solder wire and transporting a solder wire in the reaction region. In addition, the inventors have found that such a reaction region can be formed by mixing a radicalized organosilicon compound in a spiral gas flow. The present invention has been completed based on these findings.

Hereinafter, the present invention will be described in detail by dividing it into “1. coated solder wire”, “2. manufacturing method of coated solder wire”, and “3. die bonding method using coated solder wire”. The coated solder wire of the present invention is not limited by the diameter of the solder wire used as the base material. However, in the following, a solder wire having a diameter of 0.3 mm to 1.0 mm that is generally used is used. The case where it is used as a base material will be described as an example.

1. Coated Solder Wire The coated solder wire of the present invention is composed of a solder wire and a coating film made of polysiloxane provided on the surface of the solder wire. This coating film has a thickness of 4 nm to 200 nm, a difference between the maximum value and the minimum value (maximum difference) within 2.5 nm, and the ratio of the coating film to the entire coated solder wire is silicon It is characterized by being 200 mass ppm or less in terms of conversion.

(1) Solder Wire In the present invention, the composition of the solder wire is not particularly limited, and those having various compositions can be used. However, when the present invention is applied to a solder wire having the following composition, the effects of the present invention can be suitably exhibited. The composition of the solder wire can be determined by ICP emission spectroscopic analysis.

a) Pb-based solder wires Pb-based solder wires are mainly composed of Pb (lead), Sn (tin), Ag (silver), Cu (copper), In (indium), Te (tellurium), and P (phosphorus) And a solder alloy containing at least one second element selected from the group consisting of: In addition, Pb as a main component means that content of Pb with respect to the whole solder alloy is 80 mass% or more.

Such Pb-based solder wires are extremely versatile and have been used for various purposes. In recent years, the use of Pb has been restricted in consideration of the effects on the human body and the environment, but due to its versatility and ease of use, as a high temperature solder, in some applications such as joining power devices, But it continues to be used.

In the Pb-based solder wire, the total content of Pb and the second element is 95% by mass or more, preferably 97% by mass or more in total. If the total content of Pb and the second element is less than 95% by mass, it is difficult to obtain the above characteristics.

The Pb content is preferably 80% by mass to 98% by mass, and more preferably 85% by mass to 98% by mass. The content of the second element is preferably 2% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 12% by mass or less.

In addition, in the Pb-based solder wire, an element other than Pb and the second element (third element) may be contained according to the application and purpose. Examples of such a third element include Ni (nickel), Ge (germanium), Co (cobalt), Sb (antimony), Bi (bismuth), and the like. The content of these third elements is preferably 5.0% by mass or less, more preferably 4.5% by mass or less. When the content of the third element exceeds 5.0% by mass, desired characteristics may not be obtained due to the relationship between the content of Pb and the second element.

b) Sn-based solder wire The Sn-based solder wire contains Sn as a main component and contains one or more second elements selected from the group consisting of Ag, Sb, Cu, Ni, Ge, and P (phosphorus). , Composed of solder alloy. Here, Sn as a main component means that the Sn content with respect to the entire solder alloy is 80% by mass or more.

Such Sn-based solder wires have a low melting point and can be preferably applied to applications such as semiconductor devices, and are used as so-called “lead-free solder”. Here, lead-free means that the content is less than 0.01% by mass even when lead is not contained at all or as an inevitable impurity.

In the Sn-based solder wire, the total content of Sn and the second element is 95% by mass or more, preferably 97% by mass or more. If the total content of Sn and the second element is less than 95% by mass, the above characteristics cannot be obtained.

In addition, the content of Sn is preferably 80% by mass or more and 98% by mass or less, and more preferably 90% by mass or more and 98% by mass or less. The content of the second element is preferably 1% by mass to 10% by mass, more preferably 2% by mass to 7% by mass.

In addition, Sn-based solder wires may contain elements other than Sn and the second element (third element) depending on the application and purpose. Examples of such third element include In, Co, and Bi. The content of these third elements is preferably 5.0% by mass or less, more preferably 3.0% by mass or less. If the content of the third element exceeds 5.0% by mass, desired characteristics cannot be obtained due to the relationship between the contents of Sn and the second element.

(2) Coating film a) Composition and structure The coating film in this invention is comprised from polysiloxane. The type of polysiloxane is arbitrary, but from the viewpoint of suppressing the progress of oxidation on the surface of the solder wire, the main chain has a siloxane bond — (Si—O—Si) _n — (n = 1, 2, 3,. And a polyalkylsiloxane having 1 to 3 alkyl groups bonded per unit Si, particularly 2 to 3 methyl groups bonded per unit Si. Polydimethylpolysiloxane is more preferred. Such a coating film made of polysiloxane has a high density, and can thereby impart excellent oxidation resistance to the solder wire.

b) Thickness The thickness of the coating film is controlled to 4 nm to 200 nm, preferably 6 nm to 100 nm, more preferably 8 nm to 50 nm. If the thickness of the coating film is less than 4 nm, the progress of oxidation on the surface of the solder wire cannot be sufficiently suppressed, and problems such as deterioration of wetting spreadability, bondability, and generation of voids may occur. . On the other hand, if the thickness of the coating film exceeds 200 nm, the progress of the oxidation of the solder wire surface can be suppressed, but due to the effect of the coating film, the solder wire wettability and bondability are reduced, There are cases where voids are generated.

The thickness of the coating film is determined by observing each cross section with a transmission electron microscope (TEM) after cutting the coated solder wire along the length direction at three or more positions in the circumferential direction. Can be sought.

c) Thickness uniformity This coating film is also excellent in thickness uniformity. Specifically, in the coated solder wire of the present invention, the difference between the maximum value and the minimum value (maximum difference) in the thickness (diameter dimension) of the coated film is determined as the entire coated solder wire (length direction and circumferential direction). ) Over 2.5 nm, preferably within 2.0 nm, more preferably within 1.5 nm. For this reason, it can be said that the coated solder wire of the present invention has extremely small variations in characteristics such as oxidation resistance, wettability, and bondability.

d) Amount of coating In the coated solder wire of the present invention, the ratio of the coated film to the entire coated solder wire is 200 mass ppm or less, preferably 5 mass ppm to 95 mass ppm, more preferably 7 mass ppm to 50 in terms of silicon. The mass is controlled to ppm. As described above, in the coated solder wire of the present invention, since the ratio of the coating film is extremely small, it can be said that the coating film has almost no influence on the solder wire wettability and bonding property.

e) Characteristics Although the coating film constituting the coated solder wire of the present invention is extremely thin, it is firmly bonded to the metal on the surface of the solder wire and has excellent thickness uniformity. Can be evaluated. Therefore, it is possible to suppress the progress of oxidation on the surface of the solder wire, and thus it is possible to effectively suppress the deterioration of the solder wire wetting and spreadability and the generation of voids.

In addition, this coating film is colorless and transparent, and as described above, although it is formed very thin, it has excellent thickness uniformity, resulting in poor appearance such as processing unevenness and spots. There is hardly anything.

2. Manufacturing method of coated solder wire The manufacturing method of the coated solder wire of the present invention is as follows.
(1) A radicalized organosilicon compound is formed by mixing a reaction gas plasmified under atmospheric pressure with an organosilicon compound introduced via a carrier gas and radicalizing the organosilicon compound. A radicalization step;
(2) a reaction region forming step defined by a spiral gas flow and forming a reaction region in which radicalized organosilicon compounds are uniformly dispersed;
(3) A coating made of polysiloxane having a thickness of 4 nm to 200 nm on the surface of the solder wire by transporting the solder wire in the reaction region and reacting the radicalized organosilicon compound with the metal on the surface of the solder wire. A coating process for forming a film;
It is characterized by providing.

According to such a manufacturing method, a dense coating film made of polysiloxane can be uniformly formed on a solder wire by a single treatment, so that it is described in Japanese Patent Application Laid-Open No. 2014-195831. Compared with the method, productivity can be dramatically improved. In addition, this manufacturing method uses an organic silicon compound that is normally liquid as the coating material, and the coating film is formed by a dry method, so that it is not only easy to handle, but also safe. It can be evaluated that it is excellent.

(1) Radicalization process In the radicalization process, a reaction gas that has been plasmatized under atmospheric pressure and an organosilicon compound introduced through a carrier gas are mixed to radicalize the organosilicon compound, thereby producing radicals. This is a step of forming an organosilicon compound.

a) Atmospheric pressure plasma polymerization treatment Although the plasma polymerization treatment is a technique that has been widely known, the atmospheric pressure plasma polymerization treatment used in the present invention is a chemical reaction that does not proceed under normal conditions. It is made to progress by the conversion. Such an atmospheric pressure plasma polymerization process is characterized by high productivity because it is suitable for continuous processing, and has a feature that the processing cost is low because a vacuum apparatus is unnecessary, and the apparatus configuration can be simplified.

Examples of atmospheric pressure plasma include corona discharge, dielectric barrier discharge, RF discharge, microwave discharge, arc discharge, and the like, but any of them can be applied in the present invention without any particular limitation. For this reason, a known plasma generator can be used without any particular limitation as long as it can plasmify the reaction gas under atmospheric pressure. . In the present invention, atmospheric pressure includes atmospheric pressure (1013.25 hPa) and atmospheric pressure in the vicinity thereof, and also includes atmospheric pressure within the range of changes in normal atmospheric pressure.

However, in the present invention, it is necessary to mix and spray the organosilicon compound into the reaction gas that has been plasmatized in advance through a carrier gas. By adopting such a configuration, organic silicon is different from the conventional method for forming a coating film using atmospheric pressure plasma CVD, in which the reaction gas is plasmatized and the coating material is activated (plasmaized) simultaneously. Since the compound can be radicalized instantly, a dense coating film made of polysiloxane can be uniformly formed over the entire surface of the solder wire while maintaining the basic skeleton of the organosilicon compound.

b) Plasmaization conditions The conditions for converting the reaction gas to plasma should be appropriately selected according to the plasma apparatus to be used, the thickness of the target coating film, and the like. From the viewpoint of radicalizing and forming a high-quality coating film, the generator output voltage is preferably in the range of 150 V to 350 V, more preferably 200 V to 330 V. When the generator output voltage is less than 150 V, the reaction gas cannot be sufficiently converted to plasma, and thus the hydrocarbon may not be sufficiently radicalized. On the other hand, if it exceeds 350 V, there may be a problem such as damage to the apparatus.

c) Reactive gas The reactive gas is not particularly limited as long as it can be easily converted to plasma. For example, Ar (argon), He (helium), N ₂ (nitrogen), O ₂ (oxygen), Air or the like can be used. These reaction gases may be used alone or in combination of two or more at a predetermined ratio. From the viewpoint of production cost, it is preferable to use N ₂ , O ₂ , or a mixed gas thereof, particularly air.

b) Carrier gas The carrier gas is not particularly limited as long as it can transport the sprayed organosilicon compound. For example, Ar, He, N _{2 and the} like can be used. These carrier gases may be used alone or in combination of two or more at a predetermined ratio. Note that N ₂ is preferably used from the viewpoint of production cost.

c) Organosilicon compound In the present invention, an organosilicon compound that is liquid at room temperature can be used as a coating material for forming a coating film. Such an organosilicon compound includes at least one selected from the group consisting of an alkyl group, an alkoxy group, a fluoroalkyl group, an amino group, an epoxy group, an isocyanate group, a mercapto group, a vinyl group, a methacryloxy group, and an acryloxy group. It is preferable to use a compound having an organic substituent.

Specifically, those having an alkyl group include tetramethyldisiloxane (TMDSO), hexamethyldisiloxane (HMDSO), octamethyltrisiloxane (OMTSO), decamethyltetrasiloxane (DMTSO), and octamethylcyclotetrasiloxane. (OMCTSO), hexamethylcyclotrisiloxane (HMCTSO), octamethylcyclotetrasiloxane (OMCTSO), decamethylcyclopentasiloxane (DMCPSO), tetramethylcyclotetrasiloxane (TMCTSO), and the like can be used.

In addition, those having an organic substituent such as an alkoxyl group or a fluoroalkyl group include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane. , Propyltrimethoxysilane, propyltriethoxysilane, propyltriisopropoxysilane, phenyltrimethoxysilane (PTMEOS), allyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane (GPTMOS), γ-glycidoxypropyltri Ethoxysilane, γ-chloropropyltrimethoxysilane, tris (3-triethoxysilylpropyl) isocyanurate, 4-trimethoxysilylpropyloxy-2-hydroxybenzof Non, dimethyldimethoxysilane, dimethyldiethoxysilane, methylethyldimethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, diisopropyldimethoxysilane, phenylmethyldimethoxysilane, γ-glycidoxy Propylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, heptadecafluorodecylmethoxysilane, trifluoropropyltrimethoxysilane (TFPTMOS), pentafluorobutyltripropoxysilane, perfluoro Hexylethylmethoxysilane, perfluoropentylethyltrimethoxysilane, perfluorohexylethyleth Sisilane, perfluorooctylethyltrimethoxysilane, perfluoropentylethylmethyldiethoxysilane, perfluorooctylethylmethyldiethoxysilane, perfluoropentylethylmethyldipropoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltri Ethoxysilane, N- (2-aminoethyl) aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, N- (2-aminoethyl) aminopropylmethyldimethoxysilane, β- (3,4-epoxycyclohexyl) Ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, Tris (3-trimethoxysilylpropyl) isocyanurate in which isocyanate groups are bonded, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ-methacryloxypropyltri Methoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyltrimethoxysilane and the like can be used.

Among these, those having an alkyl group, particularly hexamethyldisiloxane (HMDSO) represented by the following chemical formula (Chemical Formula 1), is a colorless and odorless liquid having a boiling point of 99.5 ° C. Since it exhibits high stability and is easy to handle, it can be suitably used.

d) Amount of introduction of organosilicon compound Depending on the diameter of the solder wire forming the coating film and the plasma forming conditions, etc., but when targeting a general solder wire (diameter: 0.3 mm to 1.0 mm), The amount of the organosilicon compound introduced into 1 m of solder wire is preferably 0.006 g to 0.300 g, more preferably 0.010 g to 0.200 g, and further preferably 0.012 g to 0.075 g. preferable. If the introduced amount of the organosilicon compound is less than 0.006 g, the thickness of the coating film may be 4 nm or less, or the thickness may vary. On the other hand, if the amount of the organosilicon compound introduced exceeds 0.300 g, the thickness of the coating film may exceed 200 nm.

(2) Reaction region forming step The reaction region forming step is a step of forming a reaction region that is defined by a spiral gas flow and in which the radicalized organosilicon compound obtained in the radicalization step is uniformly dispersed.

a) Reaction region In the method for producing a coated solder wire of the present invention, a radicalized organosilicon compound is uniformly dispersed, and a reaction region in which this organosilicon compound can react with a metal on the surface of the solder wire is formed in advance. It becomes important. In addition, as long as the organosilicon compound in this reaction region is radicalized, the state is not limited and may be any state of a monomer, a semipolymer, or a polymer.

Also, in the method for producing a coated solder wire according to the present invention, it is necessary to define this reaction region by a spiral gas flow. A spiral gas flow in which radicalized organosilicon compounds are uniformly dispersed is formed, and the reaction between the metal on the solder wire surface and the radicalized organosilicon compound proceeds simultaneously and at the same rate in the reaction zone. This is because the resulting coating film can be formed extremely uniformly.

The means for forming the reaction region defined by the spiral gas flow is not particularly limited. For example, it can be formed by introducing a spiral gas flow into the apparatus in advance and mixing the radicalized organosilicon compound produced in the radicalization step described above with this spiral gas flow. Alternatively, the radicalization step may be performed outside the apparatus, and the generated radicalized organosilicon compound may be introduced into the apparatus as a spiral gas flow using a carrier gas. However, considering that the radicalized organosilicon compound is unstable and immediately returns to the normal organosilicon compound, the former method is preferable.

b) Spiral gas flow The spiral gas flow is, for example, at least one selected from the group consisting of argon, helium, nitrogen, oxygen, and air, that is, the same gas as the carrier gas described above, or these It can be formed by introducing a mixture of a radical organosilicon compound generated outside the apparatus into the gas so as to flow spirally. However, when forming a thin coating film, it is preferable to form a spiral gas flow using oxygen or air (particularly dry air). When oxygen or air is used, the amount of oxygen introduced into the coating film can be increased, and as a result, the denseness and smoothness of the coating film can be further improved.

Note that the spiral gas flow needs to be formed so that its cross-sectional area is larger than the diameter of the solder wire to be coated. Moreover, the velocity of the spiral gas flow (velocity in the direction of travel and velocity in the circumferential direction) is appropriately selected according to the thickness of the target coating film and the properties of the solder wire (reactivity with the organosilicon compound). It is necessary to do. For this reason, it is preferable to set the speed of the spiral gas flow after performing a preliminary test.

(3) Coating process The coating process is a polysiloxane having a thickness of 4 nm to 200 nm on the surface of the solder wire by conveying the solder wire in the reaction region and reacting the radicalized organosilicon compound with the metal on the surface of the solder wire. Forming a coating film comprising:

a) Solder Wire The solder wire constituting the coated solder wire of the present invention is not particularly limited, and various types can be used. However, in order to fully exhibit the effects of the present invention, it is preferable to use a solder wire obtained by a molding method described below.

[Melting raw materials]
As a method for melting the raw material, known means such as a resistance heating method, a reduction diffusion method, and a high-frequency dissolution method can be used. In particular, a high-frequency dissolution method capable of efficiently melting in a short time is preferable. A raw material melted by these methods is cast into a mold prepared in advance to form a solder mother alloy ingot having a predetermined shape. If oxygen is present during melting or casting, not only the oxidation of the raw material proceeds, but also an oxide film is involved at the time of casting, and the resulting oxide film on the surface of the solder wire becomes thicker or the surface roughness (Ra) increases. Or For this reason, it is preferable that the atmosphere at the time of melting the raw material is an inert gas atmosphere and the inert gas is circulated to the molten metal inlet of the mold at the time of casting.

[Solder wire]
When forming wire-shaped solder, a solder mother alloy ingot is formed by an extrusion method, a wire drawing method, or the like. For example, when forming by an extrusion method, it is necessary to select an appropriate extrusion temperature in accordance with the composition of the solder wire. This is because if the extrusion temperature is too high, surface oxidation tends to proceed, and conversely, if the extrusion temperature is too low, the solder wire will be extruded in a hard state, which requires a long molding time. .

Further, the extrusion is preferably performed in an inert gas, and more preferably performed while circulating the inert gas in a sealed state. This is because if oxygen is present during extrusion, the wire heated to the extrusion temperature will immediately oxidize.

[Acid cleaning and polishing]
In order to reduce the thickness of the oxide film on the surface of the solder wire or reduce the surface roughness (Ra), it is preferable to perform acid cleaning or polishing on the solder wire. The timing for performing the acid cleaning and polishing may be any timing after casting the solder mother alloy and before performing the predetermined processing, during processing, or after processing.

The type of acid used when performing acid cleaning is not particularly limited as long as it is appropriately selected depending on the composition of the solder wire, and both inorganic acid and organic acid can be used. In consideration, it is preferable to use an inorganic acid which is inexpensive and has a large oxide film removing effect. Specifically, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid and the like can be used as the inorganic acid. Moreover, citric acid, oxalic acid, etc. can be used as the organic acid. However, when a strong acid is used, due to the high dissolution rate of the solder wire in the acidic solution, partial dissolution proceeds and the surface roughness (Ra) increases or composition deviation occurs. There is. For this reason, it is preferable to use a weak acid that has a slow dissolution rate and is easy to handle. In acid cleaning, it is necessary to sufficiently consider acid concentration, cleaning time, cleaning temperature, and the like.

For example, when cleaning a Pb solder wire using a 5% aqueous acetic acid solution, it is preferable to perform acid cleaning at a cleaning temperature of about 20 ° C. and a cleaning time of about 15 minutes. In this case, the oxide film of the solder wire has the largest amount of dissolution immediately after contact with the acetic acid aqueous solution, and then gradually decreases and becomes saturated at a certain stage. Specifically, when an oxide film having a thickness of about 100 μm is cleaned, the thickness of the oxide film is reduced from 20 μm to 30 μm in about 5 minutes and is reduced to about 10 μm in about 15 minutes.

On the other hand, when polishing the surface of the solder wire, the polishing method is not particularly limited. For example, the solder wire may be sandwiched between polishing papers, pressed with an appropriate force, and wound by pulling it while being pulled.

b) Reaction between radicalized organosilicon compound and metal on the surface of the solder wire In the method for producing a coated solder wire of the present invention, the reaction between the radicalized organosilicon compound and the metal on the surface of the solder wire is performed within the reaction region described above. proceed. Specifically, as shown in FIG. 1A, the solder wire 2 serving as a base material is conveyed in the direction of arrow A through the substantially central portion of the reaction region 6 defined by the spiral gas flow 4. . At this time, since the radicalized organosilicon compound 5 is uniformly dispersed in the reaction region 6, the organosilicon compound 5 contacts the entire surface of the solder wire 2 equally by the action of the spiral gas flow 4. To do. As a result, the reaction between the radicalized organosilicon compound 5 and the metal on the surface of the solder wire 2 proceeds simultaneously and at the same reaction rate.

By the way, in the reaction region 6 as described above, the radicalized organosilicon compound 5 exists in various forms such as a monomer, a semipolymer, and a polymer. Therefore, the reaction between the radicalized organosilicon compound 5 and the metal on the surface of the solder wire 2 is as follows:
(I) an embodiment in which the radicalized organosilicon compound 5 is polymerized after reacting with the metal on the surface of the solder wire 2;
(Ii) a mode in which the radicalized organosilicon compound 5 reacts with the metal on the surface of the solder wire 2 while being polymerized, or
(iii) a mode in which the radicalized organosilicon compound 5 reacts with the metal on the surface of the solder wire 2 after polymerization,
Can be considered. The method for producing a coated solder wire according to the present invention is not limited to any embodiment as long as the coated solder wire having the above-described coated film can be obtained.

c) Solder Wire Transport Speed In the coated solder wire of the present invention, the thickness of the coating film is adjusted to a range of 4 nm to 200 nm. The thickness of the coating film can be controlled not only by the amount of the organosilicon compound introduced as the coating material and the speed of the spiral gas flow, but also by the solder wire conveyance speed. Specifically, the solder wire conveyance speed in the coating step is preferably 1 m / min to 100 m / min, more preferably 5 m / min to 80 m / min, and 10 m / min to 50 m / min. More preferably. When the conveying speed of the solder wire is less than 1 m / min, not only the coating film may be too thick, but also the productivity is significantly reduced. On the other hand, when the conveyance speed exceeds 100 m / min, the thickness of the coating film may be 4 nm or less, or the thickness may vary.

3. Die Bonding Method Using Coated Solder Wire The coated solder wire of the present invention can be used for joining various semiconductor elements and substrates, and specifically, a wide variety of semiconductors such as discrete, IC (integrated circuit) chips, modules, etc. It can be used for bonding the element and the substrate. Hereinafter, a die bonding method for bonding an IC chip to a die portion of a lead frame using the coated solder wire of the present invention will be described.

When die bonding is performed using the coated solder wire of the present invention, it is preferable to add high melting point particles to the solder wire in order to keep the IC chip horizontal. As the high melting point particles, particles having a temperature higher by 50 ° C. or more than the melting point of the solder wire are preferably used. Specifically, metal particles such as Cu and Ni, oxide particles such as SiO _2, and carbide particles such as SiC. Can be used. These high melting point particles preferably have an average particle size of 1 μm to 70 μm. The content of the high melting point particles is preferably about 1% by mass to 40% by mass with respect to the solder wire.

In general die bonding, a heater part is provided in a semi-sealed chamber provided with openings for supplying solder wires and semiconductor elements, and the substrate is transported to the heater part and heated. . At this time, an inert gas or forming gas (a gas obtained by mixing inert gas with hydrogen as a reducing gas) is circulated in the chamber. Thereafter, a solder wire is supplied onto the substrate heated to a predetermined temperature, melted, and a semiconductor element is placed on the solder wire, and the substrate and the semiconductor element are joined by pressing.

At this time, the solder wire waits in a state where a heated mixed gas of inert gas and air is sprayed at the heater portion, so that oxidation proceeds on the surface thereof. Further, although the inert gas is circulating, the chamber is not completely sealed, so that the oxidation proceeds even by oxygen flowing into the chamber when the solder wire is supplied.

In addition, in order to achieve good bonding, it is necessary to set the temperature of the heater section to a temperature about 30 ° C. to 70 ° C. higher than the melting point of the solder wire. In particular, when using a high melting point solder such as a Pb-based solder wire containing 5% by mass of Sn, the temperature of the heater must be set to about 340 ° C. to 380 ° C. Will progress further.

In such die bonding, if the coated solder wire of the present invention is used instead of the conventional solder wire, it is possible to prevent oxidation during standby and melting by the action of the coating film. Therefore, the coated solder wire of the present invention realizes bonding with excellent wettability and bondability (bonding strength) and extremely low void generation, and the manufacturing method of the present invention has such characteristics. Production of coated solder wire is easily realized on an industrial scale. Therefore, the coated solder wire of the present invention can be suitably used for production of a semiconductor element bonded substrate that requires high reliability and various devices using the substrate.

Hereinafter, the present invention will be described in more detail with reference to examples.

[Production of solder wire]
Bi, Zn, Ag, Sn, Pb, Cu, Au, In, Al, Ni, Sb, Ge, Te, and P having a purity of 99.9% or more were prepared as raw materials. In the obtained coated solder wire, in order to prevent variation in composition depending on the sampling position, large flakes and bulk materials were cut or pulverized and adjusted to a size of 3 mm or less.

A predetermined amount was weighed from the raw material adjusted in this way and put into a graphite crucible. The crucible was placed in a high-frequency melting furnace, and in order to suppress oxidation, the melting furnace was turned on in a state where 0.7 L / min or more of nitrogen per 1 kg of raw material was circulated. The raw material was melted while sufficiently stirring with a mixing rod so as not to cause variation. After confirming that the raw materials were sufficiently melted, the melting furnace was turned off, the crucible was quickly taken out, and the obtained molten metal was cast into a solder mother alloy mold to obtain solder mother alloy ingots having different compositions.

The mold used was the same as a general mold used in the production of a solder mother alloy. Each solder mother alloy ingot was processed into a wire shape using an extruder in an inert gas atmosphere. 1-No. 18 solder wires (diameter 0.76 mm) were obtained. The composition of these solder wires was measured using an ICP emission spectroscopic analyzer (manufactured by Shimadzu Corporation, ICPS-8100). The results are shown in Table 1.

(Example 1)
[Production of coated solder wire]
Sample No. 1 is wound on the surface of the solder wire being conveyed by the method shown in FIG. 1 when winding the Pb-based solder wire with a solder wire automatic winding machine (TM type winding machine manufactured by Tanabe Seisakusho Co., Ltd.). A coating film made of polysiloxane was formed using an atmospheric pressure polymerization apparatus (Plasma Polymer Lab System PAD-1 type, manufactured by Plasma Treat Co., Ltd.).

First, HMDSO (manufactured by Kanto Chemical Co., Inc.) introduced through a carrier gas (N ₂ ) is mixed with a reaction gas (N ₂ ) that has been plasmatized under atmospheric pressure, and radicals are generated by radicalizing HMDSO. HMDSO was obtained (radicalization step).

<Plasmaization conditions>
・ Transmission frequency of plasma generator: 21 kHz
-Generator output voltage: 280V
・ Pressure: Atmospheric pressure (1013.25 hPa)
On the other hand, N ₂ is introduced into the apparatus as a spiral gas flow, and radicalized HMDSO is sprayed from the nozzle of the atmospheric pressure polymerization processing apparatus to the spiral gas stream, and the spiral gas stream and radicals are sprayed. A reaction region was formed by mixing HMDSO (reaction region formation step).

In this state, a coating film was formed on the surface of the solder wire by passing the solder wire through substantially the center of the reaction region. At this time, the reaction amount of the radicalized organosilicon compound per 1 m of the solder wire was adjusted to 0.022 g, and the solder wire conveyance speed was adjusted to 15.0 m / min.

[Evaluation of coated solder wire]
The following items (a) to (e) were evaluated for the coated solder wires obtained as described above.

(A) Measurement of the thickness of the coating film After cutting the coated solder wire along the length direction at a reference position (0 °) and a position rotated by 90 ° and 180 ° with respect to the reference position, Each cross section was observed with a TEM (manufactured by Hitachi High-Technologies Corporation, transmission electron microscope HF-2000), and the thickness of the coating film was measured. The results are shown in Table 3.

(B) Evaluation of surface state The surface state at the time of producing the coated solder wire was observed using an optical microscope (Nikon Corporation, ECLIPSE M6600). As a result, the case where the surface state was almost the same as the state where the coating film was not formed was evaluated as “good (◯)”, and the case where discoloration was observed was evaluated as “bad” (x).

Further, a neutral salt spray test based on JISZ2371 was performed on the coated solder wire for 7 days, and then the surface state was observed using an optical microscope. As a result, when the surface state is almost the same as the initial state, “good (◯)”, and when the surface state is discolored compared to the initial state or the smoothness is deteriorated, “bad” (x). As evaluated. These results are shown in Table 3.

In addition, observation of the surface state after the initial stage and the neutral salt spray test was both performed at positions rotated 90 ° and 180 ° with respect to the reference position (0 °) and the reference position.

(C) Evaluation of silicon content The amount of silicon present on the surface of the coated solder wire was evaluated by measuring using an ICP emission spectroscopic analyzer. The results are shown in Table 3.

(D) After the double cover the heater portion of the wettability (wettability and bondability) Evaluation controlled atmosphere wettability tester (manufactured by company), the N ₂ from four locations around the heater unit 12L / While flowing at a flow rate of minutes, the heater temperature was set to a temperature higher by 50 ° C. than the melting point of the coated solder wire and heated. After confirming that the heater temperature was stable, a Cu substrate (plate thickness: about 0.70 mm) was placed on the heater and heated for 25 seconds. In this state, the coated solder wire cut to 5 cm was placed on the Cu substrate and further heated for 25 seconds. Thereafter, the Cu substrate was taken up from the heater portion and cooled to room temperature in a nitrogen atmosphere. After confirming that the Cu substrate was sufficiently cooled, the solder bonding state was visually observed.

As a result, when the Cu substrate and the coated solder wire are bonded and the coated solder wire has good wet spreading (when the solder after bonding is thin and spread), the bonding is determined as “good (○)”. Although it was possible to do so, the case where the coated solder wire was poorly spread (when the solder after joining was swelled) was “bad” (△), and when it was not possible to join, “impossible (×)” As evaluated. The results are shown in Table 3.

(E) Evaluation of heat cycle performance 500 cycles of heat cycle test with one cycle consisting of -55 ° C cooling and + 150 ° C heating for the Cu substrate to which the coated solder wire was joined in the wettability evaluation described above. After that, the entire Cu substrate was embedded in a resin, cross-section polishing was performed, and the joint surface was observed with an SEM (manufactured by Hitachi High-Technologies Corporation, scanning electron microscope S-4800). As a result, the case where the same joint surface as in the initial state is maintained is “good” (◯), and the case where the joint surface is peeled or the coated solder wire is cracked is “bad” (x). As evaluated. The results are shown in Table 3.

(Examples 2 to 26, Comparative Examples 1 and 2)
A coated solder wire was produced in the same manner as in Example 1 except that the coating material and the treatment conditions were changed as shown in Table 2, and the evaluations (a) to (e) were performed. The results are shown in Table 3. Moreover, about the coated solder wire obtained in Example 2, the cross-sectional TEM photograph in the position rotated 90 degrees, 180 degrees, and 270 degrees with respect to the reference value (0 degree) and the reference value is shown in FIG.

(Comparative Example 3)
Sample No. When a Pb-based solder wire 1 is wound up by an automatic solder wire winder, an atmospheric pressure polymerization treatment device (Plasma Polymer, manufactured by Plasmatreat Co., Ltd.) is applied to the surface of the solder wire being conveyed by the method shown in FIG. (Lab system PAD-1 type) was used to form a coating film made of polysiloxane.

First, (1) a transfer jig 7 capable of preventing twisting of the solder wire 2 during transfer is fixed in such a manner that the surface 7a is fixed on the bottom side, while the solder wire 2 is transferred in the direction of arrow A, the nozzle The radicalized organosilicon compound 5 was sprayed from 8 to form a coating film 3a (see FIG. 2 (a-1)). Next, (2) the transfer jig 7 is rotated 120 ° so that the surface 7b is on the bottom surface side, and then the coating film 3b is formed in the same manner as in the step (1) (FIG. 2 (b-1) )reference). Finally, (3) after the conveying jig 7 is further rotated by 120 ° so that the surface 7c becomes the bottom surface side, the coating film 3c is formed in the same manner as in the steps (1) and (2). (See FIG. 2 (c-1)).

The above-mentioned evaluations (a) to (e) were performed on the thus obtained coated solder wire. The results are shown in Table 3. FIG. 4 shows a cross-sectional TEM photograph at a reference position (0 °) and a position rotated by 90 ° with respect to the reference position.

(Comparative Example 4)
Sample No. When winding 1 Pb-based solder wire with a solder wire automatic winder, it is immersed in a silicon-based coating agent (manufactured by Toray Dow Corning Co., Ltd., APZ6601) for 10 minutes and then dried at 120 ° C. for 10 minutes. A coated solder wire was prepared.

The above-mentioned evaluations (a) to (d) were performed on the coated solder wires thus obtained. The results are shown in Table 3. In Comparative Example 4, since (d) the wettability evaluation could not join the coated solder wire and the Cu substrate, (e) the heat cycle performance was not evaluated.

(Comparative Example 5)
Sample No. When winding 1 Pb solder wire with a solder wire automatic winder, it was immersed in a fluorine-based coating agent (Fluoro Technology Co., Ltd., FG-3020C30) for 10 minutes, and then dried with cold air for 10 minutes. A coated solder wire was produced.

The above-described evaluations (a), (b), and (d) were performed on the coated solder wires thus obtained. The results are shown in Table 3. In Comparative Example 5, since (d) the wettability evaluation could not join the coated solder wire and the Cu substrate, (e) the heat cycle performance was not evaluated.

(Comparative Example 6)
Sample No. The above (b), (d), and (e) were evaluated without forming a coating film on the Pb solder wire of No. 1. The results are shown in Table 3.

(Examples 27 to 34)
A coated solder wire was prepared in the same manner as in Example 1 except that the Pb solder wire shown in Table 4 was used as the solder wire serving as the base material, and the evaluations (a) to (e) were performed. . The results are shown in Table 5.

(Comparative Examples 7 to 14)
The above (b), (d), and (e) were evaluated without forming a coating film on the Pb-based solder wires shown in Table 4. The results are shown in Table 3.

(Examples 35 to 43)
A coated solder wire was prepared in the same manner as in Example 1 except that the Sn-based solder wire shown in Table 6 was used as the solder wire serving as the base material, and the evaluations (a) to (e) were performed. . The results are shown in Table 3.

(Comparative Examples 15 to 23)
The above-mentioned (b), (d), and (e) were evaluated without forming a coating film on the Sn-based solder wires shown in Table 6. The results are shown in Table 3.

[Evaluation results]
As understood from the results shown in Table 3, Table 5, and Table 7, the coated solder wires of Examples 1 to 43 had a coating film thickness in the range of 4 nm to 200 nm, and the coating There is little variation in the thickness of the film, and the silicon content (the silicon equivalent value of the ratio of the coating film) is within 200 ppm. In particular, as can be understood from the results shown in Table 3 with reference to FIGS. 3 and 4, the coated solder wire of Example 1 has a maximum thickness difference within a range of 1.0 nm at each position. Compared with the comparative example 3 whose maximum difference is 14.2 nm, the uniformity of the coating film is dramatically improved.

In addition, the coated solder wires of Examples 1 to 43 had almost no change in the surface state before and after the neutral salt spray test, had excellent oxidation resistance, and also had good wettability and heat cycle evaluation. is there.

In addition, the processing time in Example 1 is suppressed to 1/3 or less of the processing time in Comparative Example 3. Therefore, the productivity of the coated solder wire can be greatly improved by applying the manufacturing method of the present invention.

DESCRIPTION OF SYMBOLS 1 Coated solder wire 2 Solder wire 3, 3a, 3b, 3c Coating film 4 Spiral gas flow 5 Radicalized organosilicon compound 6 Reaction region 7 Transfer jig 7a, 7b, 7c Surface of transfer jig 8 Nozzle A Solder Wire transfer direction

Claims (12)

1. A coated solder wire composed of a solder wire and a coating film made of polysiloxane provided on the surface of the solder wire,
   The coating film has a thickness of 4 nm to 200 nm, the difference between the maximum value and the minimum value of the thickness is within 2.5 nm, and the ratio of the coating film to the entire coated solder wire is equivalent to silicon A coated solder wire having a mass of 200 ppm by mass or less.
2. The solder wire contains 80% by mass or more of Pb and one or more second elements selected from the group consisting of Sn, Ag, Cu, In, Te, and P, and Pb and second The coated solder wire according to claim 1, comprising a solder alloy having a total content of 95% by mass or more with elements.
3. The solder wire contains 80% by mass or more of Sn and one or more second elements selected from the group consisting of Ag, Sb, Cu, Ni, Ge, and P, and Sn and second The coated solder wire according to claim 1, comprising a solder alloy having a total content of 95% by mass or more with elements.
4. Radicalization that forms a radicalized organosilicon compound by mixing the reaction gas plasmatized at atmospheric pressure with an organosilicon compound introduced via a carrier gas and radicalizing the organosilicon compound Process,
   A reaction zone forming step defined by a spiral gas flow to form a reaction zone in which the radicalized organosilicon compound is uniformly dispersed;
   A coating made of polysiloxane having a thickness of 4 nm to 200 nm on the surface of the solder wire by transporting the solder wire in the reaction region and reacting the radicalized organosilicon compound with the metal on the surface of the solder wire. A coating process for forming a film;
   A method for producing a coated solder wire, comprising:
5. The method for producing a coated solder wire according to claim 4, wherein in the reaction region forming step, the reaction region is formed by mixing the radicalized organosilicon compound in a spiral gas flow introduced in advance.
6. The method for producing a coated solder wire according to claim 5, wherein the spiral gas flow is formed by at least one selected from the group consisting of argon, helium, nitrogen, oxygen, and air.
7. As the organosilicon compound, at least one organic substituent selected from the group consisting of alkyl group, alkoxy group, fluoroalkyl group, amino group, epoxy group, isocyanate group, mercapto group, vinyl group, methacryloxy group, and acryloxy group The method for producing a coated solder wire according to any one of claims 4 to 6, wherein an organosilicon compound having the following is used.
8. The method for producing a coated solder wire according to any one of claims 4 to 7, wherein at least one selected from the group consisting of argon, helium, nitrogen, oxygen, and air is used as the reaction gas.
9. The method for producing a coated solder wire according to any one of claims 4 to 8, wherein at least one selected from argon, helium and nitrogen is used as the carrier gas.
10. 10. The method for producing a coated solder wire according to claim 4, wherein, in the radicalization step, the organosilicon compound is radicalized by an atmospheric pressure plasma polymerization treatment apparatus.
11. 11. The method for producing a coated solder wire according to claim 4, wherein, in the radicalization step, the amount of the organosilicon compound introduced into 1 m of the solder wire is 0.006 g to 0.300 g.
12. 12. The method for producing a coated solder wire according to claim 11, wherein a conveying speed of the solder wire in the coating step is 1 m / min to 100 m / min.

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