WO2004113013A1

WO2004113013A1 - Solder member, solder material, soldering method, method of manufacturing solder material, and solder connecting member

Info

Publication number: WO2004113013A1
Application number: PCT/JP2004/008888
Authority: WO
Inventors: Than Trong Long; Yuuji Hisazato; Junji Kajiwara; Takayuki Naba
Original assignee: Kabushiki Kaisha Toshiba
Priority date: 2003-06-24
Filing date: 2004-06-24
Publication date: 2004-12-29

Abstract

A first member (10) and a second member (11) formed of a material with different characteristics from those of the material of the first member (10) are welded to each other with a solder member (14) formed of a first solder (12) made of a low melting point metal element or a low melting point alloy and a second solder (13) made of a metal element or an alloy with solidifying and expanding properties. The surface of the second solder (13) is covered by a reaction prevention film (15) functioning as a boundary layer or a boundary film. Thus, the performance of the solder member (14) can be maximized by maintaining the specific characteristics to the first solder (12) and the second solder (13).

Description

Specification

Solder member, solder material, soldering method, solder material manufacturing method, and solder joint member

Technical field

The present invention relates to a solder member, a solder material, a soldering method, a method of manufacturing a solder material, and a solder joint member having excellent heat conduction characteristics and mechanical properties.

Background art

[0002] In recent years, with an increasing interest in environmental issues from the viewpoint of global environmental protection, an increase in the amount of industrial waste disposal has become a serious problem. Included in industrial waste, for example

In addition, solder is used for power control computer boards, home appliances, personal computers, etc., and harmful heavy metals such as lead may flow out of the solder. For example, when lead spills out, it acts on acid rain and produces an aqueous solution containing lead, which may enter groundwater.

[0003] In Japan, the Home Appliance Recycling Law was enacted in 1998, and in 2001 it is obliged to collect used home appliances. In Europe, the EU's Directive on Waste Electrical and Electronic Products has banned the use of certain substances, including lead, since 2004. As described above, legislation on the use of lead has been strengthened, and the development of lead-free solder has been rushed (for example, see Non-Patent Document 1).

[0004] Solder plays an important role in mechanically and electrically connecting a plurality of component parts used in an environment under severe conditions involving thermal cycling, mechanical shock, mechanical vibration, and the like. Free soldering also requires mechanical and physical properties equivalent to those of Sn-Pb solders that have been used in the past.

[0005] However, in the conventional joining of electronic products using solder, for example, due to different thermal expansion coefficients of an electronic component, a substrate, a base, and the like, a large distortion is generated in a soldered joint, and deformation and deformation of these component components are caused. In some cases, fatigue breakdown due to stress concentration occurred, eventually leading to product life. In addition, due to deformation of the base and the like, it becomes impossible to make full contact with the radiation fins and the like connected to them, and the radiation efficiency may be significantly reduced. I got it. For example, when using a Sn-Cu-based lead-free solder for soldering a ceramic substrate and a Cu base that supports the ceramic substrate, the Cu base deforms significantly after soldering due to the difference in the thermal expansion coefficient between the ceramic and the metal. In addition, mechanical properties such as heat conduction characteristics and fatigue strength are significantly reduced, and required characteristics cannot be secured.

[0006] In addition, in joining electronic products using conventional lead-free solder, a large number of void defects are generated due to insufficient wettability, and sufficient solder strength cannot be provided. In some cases, conductivity could not be obtained. In a state having such a joint, thermal fatigue failure or the like may occur, and eventually the product life may be reached.

[0007] For example, in a Sn-Cu alloy, in order to secure mechanical properties such as solder strength and thermal fatigue strength, the eutectic composition Sn-0.7% by weight〇1 or the Cu content is 0.7%. A Sn alloy near 7 is used. In such an Sn—Cu alloy, Cu concentrates in front of the solidification of (Sn) dendrites, in which the amount of solid solution of Cu in Sn is about 0.006% by weight, and (Sn):

A eutectic structure of 5 6 n43.5-5-45.5 atomic%) or a eutectic structure of primary crystals η, (β Sn) and η is formed. These eutectic structures may have cracks when cooled due to low mechanical strength (for example, see Non-Patent Document 2).

Non-Patent Document 1: Proposal for a Directive of the European Parliament and of tne Council on Waste Electrical and Electronic Equipment, Commission of the European Communities, Brussels, 13.6.2000

Non-Patent Document 2: "Sn-Pb Solder Wettability Analysis of Cu and Cu-Sn Compounds", R & D Review, Central Research Institute of Toyota, Vol. 31, No. 4 (December 1996)

Disclosure of the invention

[0008] The present invention provides a solder member, a solder material, a soldering method, a method for manufacturing a solder material, and a solder member capable of suppressing a decrease in heat conduction characteristics and mechanical properties and improving solder strength and reliability. An object is to provide a solder joint member.

[0009] A solder member according to the present invention is a solder member for joining a first member and a second member made of a material having a different characteristic from the first member, wherein the first member includes a first solder phase and the first solder phase. A second solder phase having a melting point lower than that of the first solder phase and having a property of solidification and expansion; and a boundary between the first solder phase and the second solder phase. Exists in A boundary layer having a higher melting point than the first solder phase.

[0010] The solder material of the present invention is a solder material for joining a first member and a second member made of a material having different properties from the first member, wherein the first solder material and the first solder material And a second solder material having a melting point lower than that of the first solder material and having solidification and expansion properties.

[0011] In the soldering method of the present invention, the first member and the first member may be made of a material having different characteristics.

A soldering method for joining two members, wherein a boundary film is formed on the surface, and the material has a second melting point lower than the first melting point of the material forming the boundary film. A second solder material disposing step of disposing a second solder material having the following on the surface of the first member: and a step of disposing a second solder material having a lower melting point than the first melting point and a lower melting point on the second solder material. A first solder material arranging step of arranging a first solder material having a third melting point that is higher than the first solder material; a second member arranging step of arranging the second member on the first solder material; A heating step of heating the laminated member laminated through the two-member installation step at a temperature higher than the second melting point and lower than the first melting point in the atmosphere or in an inert gas atmosphere; It is characterized by having.

[0012] The method for producing a solder material according to the present invention includes a second solder comprising at least one of Bi and Sb, a Sn-based alloy containing 50% by weight or more of Bi, a Sn-based alloy containing 6% by weight or more of Sb. A boundary film forming step of forming a reaction suppression boundary film on the surface of the phase powder; and forming a first solder phase composed of Sn or a Sn-based alloy having an average diameter of 110 / im with the powder of the second solder phase. A mixture preparing step of preparing a mixture in which powder and a powder are uniformly mixed at a predetermined ratio; and a paste for mixing a flux and a binder at a predetermined ratio with the mixture and stirring to form a first mixture. And a step of preparing a mixture of particles.

[0013] Further, the method for producing a solder material of the present invention is characterized in that a Sn-based alloy containing 50% by weight or more of Bi, a Sn-based alloy containing 6% by weight or more of Sb, and at least one of Bi and Sb. (2) a boundary film forming step of forming a reaction suppression boundary film on the surface of the solder phase powder, and comprising Sn or a Sn-based alloy having an average diameter of 100 μm with the second solder phase powder. A mixture preparing step of preparing a mixture in which the first solder phase is uniformly mixed at a predetermined ratio, a compounding step of pressing and heating the mixture to form a composite, and a film forming the composite mixture. A molding process for molding into a shape of a wire or a wire.

[0014] The solder material of the present invention is characterized by comprising a Sn-based alloy containing 0.002 to 2.0% by weight of Co and containing Sn or Pb.

[0015] Further, the solder material of the present invention is characterized in that it contains 0.0-2.0% by weight of Co and 0.02-7.5% by weight of Cu, and the balance consists of Sn and inevitable impurities. And

[0016] Furthermore, the solder material of the present invention contains 0.012% by weight of a first auxiliary component composed of at least one kind of metal selected from Cu, Ag, Au, Co and Ni, and contains Mn, It contains 0.02 to 1.2% by weight of a second auxiliary component composed of at least one metal selected from Pd and Pt, with the balance being Sn and unavoidable impurities.

[0017] The solder material of the present invention contains a Sn-based alloy containing 0.0-2.0% by weight of Co, Sn or Pb, or 0.0-2.0% by weight of Co, 0.02-7.5% by weight, with the balance comprising a first solder consisting of Sn and unavoidable impurities, and a second solder consisting of an Sn-based alloy containing no Sn or Pb. .

[0018] The solder joint member of the present invention is a Sn-based alloy containing 0.0-2.0% by weight of Co, Sn or Pb, or 0.02-2.0% by weight of Co, The first member and the second member are joined by using a solder material containing 0.02-7.5% by weight and a balance of Sn and unavoidable impurities.

[0019] A solder member of the present invention is a solder member for joining a first member and a second member, and is a Sn-based alloy containing 0.02 to 2.0% by weight of Co and containing no Sn or Pb. A first solder phase consisting of: Bi, Sb dispersed in the first solder phase so as to have a plurality of regions, having a lower melting point than the first solder phase, and having the property of solidification expansion; , Ga, Ge, Bi alloy, Sb alloy, Ga alloy, Ge alloy and a second solder phase made of one kind of material selected from the group consisting of Ge alloy.

[0020] The solder material of the present invention comprises a Sn-based alloy containing 0.05 to 2.0% by weight of Co, not containing Sn or Pb, or 0.02 to 2.0% by weight of Co, and 02—7.5 contains 5% by weight A first solder consisting of Sn and inevitable impurities, and a Bi, Sb, Ga, Ge, Bi alloy, Sb alloy, Ga alloy having a melting point lower than that of the first solder and having a solidification expansion property And a second solder made of one material selected from the group consisting of Ge alloys.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a sectional view schematically showing a solder member and a solder material according to a first embodiment of the present invention.

FIG. 1B is a cross-sectional view schematically showing a solder member and a solder material according to the first embodiment of the present invention.

FIG. 2 is a diagram showing characteristics of a first solder and a second solder during solidification.

FIG. 3A is a sectional view schematically showing a solder member and a solder material according to the first embodiment of the present invention.

FIG. 3B is a cross-sectional view schematically showing a solder member and a solder material according to the first embodiment of the present invention.

FIG. 4A is a sectional view schematically showing a solder member and a solder material according to the first embodiment of the present invention.

FIG. 4B is a cross-sectional view schematically showing a solder member and a solder material according to the first embodiment of the present invention.

FIG. 5A is a sectional view schematically showing one example of a solder material according to the first embodiment of the present invention.

FIG. 5B is a cross-sectional view schematically showing one example of a solder material according to the first embodiment of the present invention.

FIG. 5C is a cross-sectional view schematically showing one example of a solder material according to the first embodiment of the present invention.

FIG. 6A is a cross-sectional view of a Cu base showing a deformation amount of the Cu base.

FIG. 6B is a cross-sectional view of the Cu base showing the amount of deformation of the Cu base.

FIG. 7 is a sectional view schematically showing a solder material according to a second embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view after soldering using a solder material according to a second embodiment of the present invention. FIG.

FIG. 9 is a cross-sectional view schematically showing one example of a soldering structure using a solder material according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view schematically showing a cross section after soldering using the solder material according to the second embodiment of the present invention.

FIG. 11 is a cross-sectional view schematically showing a cross section after soldering using a conventional solder material.

FIG. 12 is a cross-sectional view schematically showing one example of a soldering structure using the solder material according to the second embodiment of the present invention.

FIG. 13 is a cross-sectional view schematically showing a cross section after soldering using the solder material according to the second embodiment of the present invention.

FIG. 14 is a cross-sectional view schematically showing a cross section after soldering using a conventional solder material.

FIG. 15 is a perspective view showing the appearance of a film-like solder material.

FIG. 16 is a perspective view showing the appearance of a wire-shaped solder material.

FIG. 17 is a perspective view of a lead-free solder formed in a film shape according to a third embodiment of the present invention.

FIG. 18 is a sectional view of a lead-free solder formed in a paste according to a third embodiment of the present invention.

FIG. 19 is a perspective view of a lead-free solder formed in a wire shape according to a third embodiment of the present invention.

FIG. 20 is a perspective view of a lead-free solder formed in a rod shape according to a third embodiment of the present invention.

FIG. 21 is a cross-sectional view of a first element member and a second element member joined by lead-free solder.

FIG. 22 is a cross-sectional view of a first element member and a second element member joined by two types of lead-free solder.

FIG. 23 is a sectional view of a solder joint. FIG. 24 is a diagram showing an outline of measurement of surface tension by a dropping method.

FIG. 25A is a view showing a result of elemental analysis.

FIG. 25B is a view showing a result of elemental analysis.

FIG. 26 is a view showing a result of elemental analysis.

FIG. 27A is a view showing a soldering step according to a fourth embodiment of the present invention.

FIG. 27B is a view showing a soldering step according to a fourth embodiment of the present invention.

FIG. 27C is a view showing a soldering step according to a fourth embodiment of the present invention.

FIG. 27D is a diagram showing a soldering step according to the fourth embodiment of the present invention.

FIG. 27E is a view showing a soldering step according to the fourth embodiment of the present invention.

FIG. 28 is a cross-sectional view of a first element member on which oxidation-resistant solder is installed.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment)

1A and 1B show an example of a soldering structure according to the first embodiment.

In the soldering structure shown in FIG. 1B, the first member 10 and the second member 11 made of a material having a different characteristic from the first member 10 are connected to the first member 10 made of a low melting point metal element or a low melting point alloy. It is joined by a solder member 14 made of a solder 12 and a second solder 13 made of a metal element or alloy having the property of solidification expansion. The surface of the second solder 13 is covered with a reaction prevention film 15 functioning as a boundary layer or a boundary coating. Here, the heterogeneous material refers to a material having different properties such as mechanical properties and physical properties irrespective of the same or different composition.

[0025] The metal used for the first solder 12 is a low-melting-point metal element or a low-melting-point alloy, such as an elemental metal such as Sn, In, or Zn, or a Sn alloy, an In alloy, or a Zn alloy. Is done. In Sn alloys, the content of Sn in the alloy is appropriately set depending on the mechanical properties, melting point, and the like required for the alloy. In the case where other In alloys or Zn alloys are used, similarly to the case of Sn alloy, the content is appropriately set according to the mechanical properties, melting point, and the like required for the alloy. Note that, for example, the Sn alloy may contain elemental metals such as In and Zn. Similarly, the In alloy and the Zn alloy may contain other elemental metals. [0026] The metal used for the second solder 13 is composed of an elemental metal such as Bi, Sb, Ga, or Ge having the property of expanding when solidified, or a Bi alloy, Sb alloy, Ga alloy, Ge alloy, or the like. . When the metal used for the second solder 13 is an alloy, Sn or the like is contained. When a Bi alloy is used for the second solder 13, the content of Bi in the Bi alloy may be 50% by weight or more, and more preferably 58% by weight or more. If the Bi content is less than 50% by weight, the effect of relieving the thermal shrinkage of the first solder 12 due to expansion of the Bi alloy is small. If the content is less than 48% by weight, the effect is hardly obtained. In the Sb alloy, Ga alloy and Ge alloy, the content of Sb, Ga and Ge is preferably at least 22% by weight, more preferably at least 6% by weight, and further preferably at least 50% by weight. For example, if the content of Sb in the Sb alloy is less than 6% by weight, the effect of reducing the thermal shrinkage of the first solder 12 due to the expansion of the Sb alloy is hardly obtained. The second solder 13 may be formed by combining element metals such as Bi, Sb, Ga, and Ge described above. Further, for example, the Bi alloy may contain an elemental metal such as Sb, Ga, and Ge. Similarly, Sb alloys, Ga alloys, and Ge alloys may contain other elemental metals.

[0027] Further, the content of the second solder 13 in the first solder 12 depends on the amount of strain in the solder phase calculated from the difference between the coefficients of thermal expansion of the first member 10 and the second member 11 by 5-50 volume. It is set appropriately within the range of%. If the content of the second solder 13 is less than 5% by volume, a sufficient solidification and expansion effect cannot be obtained, and if it exceeds 50% by volume, the ductility of the composite solder phase is reduced, and sufficient mechanical properties are secured. This is because it may not be possible.

As the second solder 13, a metal or an alloy having a melting point lower than the melting point of the first solder 12 is used, and the metal used for the first solder 12 and the second solder 13 is adjusted to meet the conditions. Selection and combination of a group element, an alloy type, an alloy composition, and the like are appropriately performed. Thereby, the effect of alleviating the internal stress in the solder member due to the difference in the thermal expansion coefficient between the first member 10 and the second member 11 can be maximized.

The reaction prevention film 15 formed on the surface of the second solder 13 is formed of a metal, a ceramic, or a resin having a melting point higher than the melting point of the material forming the first solder 12.

When the reaction prevention film 15 is formed of a metal, the metal may be, for example, Cu, Ni, Cr, Al, Zn, Au, Ag, Cu alloy, Ni alloy, Cr alloy, Al alloy, Zn alloy, Au alloy. Alloy and Ag It is appropriately selected from at least one of the alloys. The reaction prevention film 15 made of metal is formed on the surface of the second solder 13 by an electrolytic plating method, an electroless plating method, or the like.

When the reaction prevention film 15 is formed of ceramics, examples of the ceramics include, but are not limited to, Al 2 O 3, SiO, A1N, SiN, SiC, TiC, and TiO.

2 3 2 2 At least one of them is appropriately selected. The reaction prevention film 15 made of ceramics is formed by, for example, a sol-gel method, and this forming method is extremely easy and economical.

When the reaction prevention film 15 is formed of a resin, for example, a thermoplastic resin is used as the resin, and the reaction prevention film 15 is formed by a method of coating a molten resin or a method of adhering fine particles through a binder. And so on.

The thickness of the reaction prevention film 15 is appropriately set within a range of 10 nm and 10 μm according to the required characteristics of the solder member. If the thickness of the reaction preventive film 15 is 10 nm or more, the effect of preventing the reaction between the first solder 12 and the second solder 13 is exhibited.If the thickness exceeds 10 zm, the formation time of the reaction preventive film 15 becomes longer, which is uneconomical. is there. A more preferable range of the thickness of the reaction prevention film 15 is 0.1 μm to 5 μm.

[0034] The soldering conditions such as the soldering temperature and the holding time are controlled to suppress the diffusion or alloying reaction, and the respective mechanical and physical properties of the first solder 12 and the second solder 13 are controlled. If this can be maintained, the reaction prevention film 15 may not be provided. For example, the first solder 12, Sn- 0. 7 wt% Cu- 3. 5 wt% eight _§ (solidus: 217 ° C, liquidus: 219 ° C), as the second solder 13, Sn- 57% by weight Bi (melting temperature: 139 ° C) is selected and the soldering temperature is 10-20 ° C higher than the liquidus temperature of the first solder 12, and the first solder 12 is completely melted. Heating for a minimum holding time required to perform the heating, for example, 10 seconds. Under these soldering conditions, when soldering, an alloy reaction layer with a thickness of several μm is formed at the boundary layer between the first solder 12 and the second solder 13, but the first solder 12 and the second solder 13 are completed. The inherent physical and mechanical properties of the first solder 12 and the second solder 13 that cannot be completely alloyed can be maintained.

Here, as shown in FIG. 1B, FIG. 3B and FIG. 4B, when the first member 10 is larger than the thermal expansion coefficient of the second member 11, the second solder 13 is replaced with the first member in the first solder 12. By being unevenly distributed on the 10 side, the effect of maximally relaxing the distortion of the first member 10 during solidification can be obtained. it can.

[0036] The solder member shown in FIG. 1B, FIG. 3B and FIG. 4B is manufactured, for example, as follows.

First, a material for forming the reaction preventive film 15 of the second solder 13 is selected. If the selected material is a metal, an electrolytic plating method, an electroless plating method, or the like is used. In this case, the reaction preventing film 15 is formed on the surface of the second solder 13 by a sol-gel method or the like, and further when the selected material is a resin by a coating method or the like.

[0038] A predetermined amount of the second solder 13 coated with the reaction prevention film 15 thus obtained is uniformly arranged on the surface of the first member 10. Subsequently, a predetermined amount of the first solder 12 is uniformly arranged on the second solder 13. Then, the second member 11 is placed on the first solder 12 to obtain a laminated member as shown in FIGS. 1A, 3A and 4A. Subsequently, the laminated member is heated to a temperature equal to or higher than the liquidus temperature of the first solder 12 in the atmosphere or an inert gas atmosphere. The first solder 12 melted by heating is impregnated into the gap between the second solders 13. In the cooling step, when passing through the melting point of the first solder 12, the first solder 12 solidifies while surrounding the second solder 13 which has a lower melting point than the first solder 12 and is still molten. When further cooled, the second solder 13 solidifies when passing through the melting point of the second solder 13. When the second solder 13 solidifies, it expands in volume and exerts the effect of alleviating the strain in the solder phase due to the difference in the coefficient of thermal expansion between the first member 10 and the second member 11, and as shown in FIGS. 1B, 3B and 4B. A solder member that does not undergo deformation due to the difference in thermal expansion coefficient as shown is obtained. 5A, 5B, and 5C, a solder member in which the second solder 13 is unevenly distributed in the first solder 12 in advance may be used.

Here, as shown in FIG. 1A, the first solder 12 is formed in a plate shape, and the second solder 13 is formed in a spherical or irregular particle shape. Further, as shown in FIG. 3A, the first solder 12 may be formed in a spherical or irregular shape particle shape, similarly to the second solder 13. Further, as shown in FIG. 4A, the first solder 12 may be formed in a plate shape, and the second solder 13 may be formed in a plate shape having a through hole. The shapes of the first solder 12 and the second solder 13 are not limited to the shapes and combinations shown in FIG. 1A, FIG. 3A and FIG. If the first solder 12 impregnates the voids between the second solders 13, it is sufficient.

Referring to the solder member, the solder material, and the soldering method in the first embodiment, as shown in FIG. 2, the solder member 14 due to the difference in thermal expansion coefficient between the first member 10 and the second member 11 is determined. Generation of internal stress in the inside is suppressed, and as a result, deformation of the first member 10 and the second member 11 can be reduced. In particular, by unevenly distributing the second member 11 on the side of the member having a large thermal expansion coefficient, the generation of internal stress in the solder member 14 due to the difference in the thermal expansion coefficient between the first member 10 and the second member 11 can be effectively reduced. Can be suppressed.

Further, since the second solder 13 is covered with the reaction prevention film 15, no diffusion or alloying reaction occurs between the first solder 12 and the second solder 13. Second, 13 cannot be alloyed. As a result, the unique properties such as the mechanical properties of the first solder 12 and the solidification and expansion properties of the second solder 13 are maintained, and the performance of the solder member 14 can be maximized. .

Next, a specific example of the first embodiment will be described.

(Example 1)

3 ₁ 1-57 wt% 81 powder surface with an average particle size of about 20 111, sol. Gel method, to form a A1_rei film having a thickness of about 50 nm, were fabricated second solder. Then, with this second solder

twenty three

A composite solder material was manufactured by mixing a first solder made of Sn-0.7% by weight Cu powder having an average particle size of about 20 μ はんだ η so that the content of the second solder was 15% by volume. For the composite solder, a creamy composite solder was prepared by adding an appropriate amount of flux and a resin binder to facilitate removal of the oxide film on the surface of the bonding material, screen printing, and application. .

Subsequently, a composite solder having a thickness of about 100 zm was screen-printed on the surface of the first oxygen-free Cu-based member having a thickness of 3 mm, a width of 100 mm, and a length of 200 mm. Then, a second member of a 0.3 mm thick, 80 mm wide, 180 mm long SiN substrate lined with 100 zm thick pure Cu on both sides is placed on the screen printed composite solder. Thus, a laminated joining member was formed. Subsequently, this laminated joint member was placed in an N gas atmosphere at a temperature of 250 ° C. for 3 minutes.

Two

During heating, soldering was performed.

[0045] The shear strength of the solder phase at the soldered portions of the soldered first member and second member As a result of measuring and evaluating the degree, the shear strength was 30 MPa. The deformation of the Cu base of the first member was 75 μm.

Here, the deformation amount of the Cu base will be described with reference to FIGS. 6A and 6B.

FIGS. 6A and 6B show a cross section in the longitudinal direction at the center of the width of a Cu base having a thickness of 3 mm, a width of 100 mm, and a length of 200 mm, which constitutes the first member 10. FIG. 6A shows a cross section of the first member 10 before deformation, and FIG. 6B shows a cross section of the first member 10 after deformation.

[0048] The deformation amount of the Cu base indicates the maximum deformation distance L between the reference surface 20 and the contact surface 21 of the first member 10 that was in contact with the reference surface 20 in a direction perpendicular to the longitudinal direction of the first member 10. It is.

(Example 2)

An A1〇 film having a thickness of about 50 nm was formed on the surface of Sn—57 wt% 81 powder having an average particle size of about 20 × m by a sol-gel method, and a second solder was manufactured. Subsequently, thickness 100 / im, width

twenty three

An 80mm, 180mm long Sn-0.7% by weight Cu sheet is placed on one side of a first solder, and a second solder is placed so that the content of the second solder is 15% by volume and press-molded. Thus, a composite solder sheet was manufactured.

[0050] Subsequently, an appropriate amount of flux was dropped on the surface of the oxygen-free Cu-based first member having a thickness of 3mm, a width of 100mm, and a length of 200mm, and the surface of the second solder layer of the composite solder sheet was moved to the first surface. A composite solder sheet was placed on the surface of the first member so as to be in contact with the member. Then, on the composite solder sheet, a second member of SiN substrate 0.3 mm thick, 80 mm wide and 180 mm long lined with pure Cu with a thickness of 100 / im on both sides The members were configured. Subsequently, the laminated joining member was heated at a temperature of 250 ° C for 3 minutes in an N gas atmosphere.

Two

, And soldered.

As a result of measuring and evaluating the shear strength of the solder phase in the soldered portions of the soldered first member and second member, the shear strength was 32 MPa. The deformation of the Cu base of the first member was 80 μm.

(Example 3)

Sn-10% by weight with an average particle size of about 20 μm 31) A 50 nm thick Si〇 film was formed, and a second solder was fabricated. Then, this second solder

Two

Average particle size and a first solder consisting of Sn- 2 wt% Rei_11 one 0.2 wt% eight _§ powder about 20 mu m, the content of the second solder is mixed so that 25% by volume and Manufactured a composite solder material. In order to remove the oxide film on the surface of the bonding material and to facilitate screen printing and coating, a suitable amount of flux and resin binder were added to the composite solder to prepare a creamy composite solder.

Subsequently, a composite solder having a thickness of about 100 zm was screen-printed on the surface of the first member based on oxygen-free Cu having a thickness of 3 mm, a width of 100 mm, and a length of 200 mm. Then, a second member of a 0.3 mm thick, 80 mm wide, 180 mm long SiN substrate lined with 100 zm thick pure Cu on both sides is placed on the screen printed composite solder. Thus, a laminated joining member was formed. Subsequently, the laminated joining member is placed in an N gas atmosphere at a temperature of 300 ° C for 3 minutes.

Two

During heating, soldering was performed.

[0054] As a result of measuring and evaluating the shear strength of the solder phase in the soldered portions of the soldered first member and second member, the shear strength was 50 MPa. The deformation of the Cu base of the first member was 125 / im.

(Comparative Example 1)

Using the composite solder sheet of Sn—0.7% by weight〇11 used in Example 2, the first member and the second member were soldered under exactly the same conditions as in Example 2.

[0056] As a result of measuring and evaluating the shear strength of the solder phase at the soldered portions of the soldered first member and second member, the shear strength was 35 MPa, which was almost the same value as that of Example 2. . On the other hand, the deformation amount of the Cu base of the first member is 500 / m, which is 6 times or more as compared with the deformation amount of Example 2.

From the results and the result of Example 2, it is possible to obtain the solidification and expansion effect of the second solder by including the second solder composed of Sn—57% by weight Bi, and to obtain the Cu base of the first member. It can be seen that the deformation of can be suppressed.

(Comparative Example 2)

Thickness 100 μ πι, width 80 mm, length 180mm Sn_0. 7 weight ^_0/0 Cu on one surface of the first'm made of sheet, the Al O film formed Shinare, Sn- 57 wt% 81 2nd powder made of powder

twenty three However, the solder was installed so that the content of the second solder was 15% by volume, and pressed to produce a composite solder sheet. Subsequently, the first member and the second member were soldered under exactly the same conditions as in Example 2.

[0059] As a result of measuring and evaluating the shear strength of the solder phase at the soldered portions of the soldered first member and second member, the shear strength was 25 MPa, which was lower than the shear strength of Example 2. . Further, the deformation amount of the Cu base of the first member is 350 × m, which is four times or more as compared with the deformation amount of the second embodiment.

From this result and the result of Example 2, by forming a boundary layer on the surface of the Sn—57% by weight81 powder of the second solder to prevent alloying of the first solder and the second solder, It can be seen that the mechanical properties of the first solder and the solidification and expansion properties of the second solder can be maintained.

[0061] Here, the measurement results of the above Examples and Comparative Examples are summarized in Table 1.

[table 1]

(Second Embodiment)

FIG. 7 shows an example of the solder material according to the second embodiment.

[0063] The solder material 100 contains a first solder powder 101 made of Sn or an Sn alloy constituting a mother phase, and a second solder powder 102 made of a Bi alloy or an Sb alloy constituting a second phase. The surface of the second solder powder 102 is covered with a reaction control boundary film 103. The solder material 100 shown in FIG. 7 is a paste-like solder material in which a flux and a binder are mixed in a mixture in which the first solder powder 101 and the second solder powder 102 are uniformly mixed.

As shown in FIG. 8, the cross section after soldering using this solder material is composed of a mother phase 104 formed by melting and solidifying the first solder powder 101 and a second solder powder 102. Melts And a second phase 105 that is solidified.

[0065] The first solder powder 101 is composed of Sn or a Sn alloy. In the case of a Sn alloy, the Sn content in the alloy is appropriately set according to the mechanical properties, melting point, and the like required for the alloy. . Further, the average particle size of the first solder powder 101 is preferably in the range of 100 to 100 x m. If the average particle size of the first solder powder 101 is less than l x m, it is difficult to handle and the cost is high. On the other hand, if the average particle size of the first solder powder 101 exceeds lOO xm, it is difficult to uniformly disperse the second solder powder 102, and the effect of reducing the thermal shrinkage of the matrix 104 may not be sufficiently exhibited. is there. In addition, by using the first solder as a powder, the mixing ratio with the second solder powder 102 can be easily adjusted.

The second solder powder 102 is made of, for example, a Sn alloy containing B or Sb, which has the property of expanding when solidified, as described in the first embodiment. Also, the second solder powder 102 may be composed of B or Sb alone. Here, when a Sn alloy containing Bi is used for the second solder powder 12, the content of Bi in the Sn alloy is preferably 50% by weight or more, more preferably 58% by weight or more. If the Bi content is less than 50% by weight, the effect of relieving the thermal shrinkage of the matrix 14 is small because the solidification expansion of the Bi alloy is small. When a Sn alloy containing Sb is used for the second solder powder 12, the content of Sb in the Sn alloy is preferably at least 6% by weight, more preferably at least 22% by weight. If the Sb content is less than 6% by weight, the effect of relieving the thermal contraction of the parent phase 14 is small because the solidification expansion of the Sb alloy is small. The second solder powder 102 may be configured by combining Bi and Sb. When a Sn alloy containing Bi is used for the second solder powder 12, Sb may be contained in the Sn alloy. Further, when using a Sn alloy containing Sb in the second solder powder 12, Bi may be contained in the Sn alloy.

The average particle size of the second solder powder 102 is preferably in the range of 1 to 100 μm. If the average particle size of the second solder powder 102 is less than lxm, it is difficult to handle and the cost becomes higher.If the average particle size exceeds ΟΟ ΟΟ μm, it is difficult to disperse uniformly in the matrix 104, The effect of alleviating shrinkage may not be fully exhibited.

[0068] Furthermore, the content of the second solder powder 102 in the solder material containing the flux and the binder is calculated based on the thermal shrinkage of the component to be soldered, which is calculated based on the coefficient of thermal expansion, and the amount of the solder. It is set appropriately according to the amount of solidification shrinkage of the solder material calculated from the size of the recesses and holes of the component parts to be supplied and the properties of the alloy of the solder base material.

[0069] The content of the second solder powder 102 in the solder material is preferably in the range of 5 to 50% by volume. If the content of the second solder powder 102 is less than 5% by volume, the effect of alleviating the thermal shrinkage of the mother phase 104 is small, and it can be applied even if it exceeds 50% by volume, but further improvement of the effect cannot be expected.

The second solder powder 102 is made of a metal or an alloy having a melting point lower than the melting point of the first solder powder 101. The type, composition, and the like of the metal of the second solder powder 102 are appropriately selected so as to correspond to the first solder powder 101 and have a lower melting point than the first solder powder 101. Thereby, the effect of alleviating the solidification contraction of the matrix 104 can be maximized.

The reaction control boundary film 103 formed on the surface of the second solder powder 102 is formed of a metal having a melting point higher than the melting point of the material forming the second solder powder 12. This reaction control boundary film 103 is formed of the same material as the reaction prevention film 15 shown in the first embodiment. As described in the first embodiment, the soldering conditions such as the soldering temperature and the holding time are controlled to suppress diffusion or alloying reaction, so that the first solder powder 101 and the second solder powder are controlled. If the mechanical properties, physical properties, and the like of 102 can be maintained, the reaction control boundary film 103 may not be provided.

The reaction control boundary film 103 is formed on the surface of the second solder powder 102 by an electroless plating method or the like. Further, the reaction control boundary film 103 may be formed by a sol-gel method. In the sol-gel method, for example, a metal film can be formed on the surface of the second solder powder 102 by immersing the second solder powder 102 in an alumina sol using a metal alkoxide as a raw material and subsequently drying the powder. The method of forming the reaction control boundary film 103 is not limited to these, but the reaction control boundary film 103 can be economically formed by using the electroless plating method or the sol-gel method.

[0073] The thickness of the reaction control boundary film 103 is appropriately set in the range of 10 nm x 10 xm according to the required characteristics of the solder material. If the thickness of the reaction control boundary film 103 is 10 nm or more, diffusion or alloying reaction between the parent phase 104 and the second phase 105 can be prevented, and Exceeding the time limit makes the formation time of the reaction control boundary film 103 long, which is uneconomical.

[0074] The flux mixed into the mixture of the first solder powder 101 and the second solder powder 102 removes an oxide film between the soldered material and the member joined by the solder material, and reheats during heating. It is to prevent oxidation. As the flux, a commonly used activator such as an amine halide or an organic acid is used. The content of the flux in the solder material including the flux and the binder can be appropriately set in the range of 5 to 10% by weight. When the flux content is less than 5% by weight, the effect of removing the oxide film between the solder material and the member joined with the solder material and preventing the oxidation again during heating is small, and exceeds 10% by weight. Within the range, the effect cannot be improved.

[0075] The binder mixed with the first solder powder 101 and the second solder powder 102 is composed of a polymer material and alcohol. The content of the binder in the solder material including the flux and the binder can be appropriately set in the range of 520% by weight. If the binder content is less than ¾% by weight, the adhesion of the solder material applied or printed on the surface of the component parts will be insufficient, and if it exceeds 20% by weight, the binder will flow out of the solder member and work efficiency will be reduced. May be reduced.

According to this solder material, the second solder powder 102 having the property of expanding at the time of solidification is included in the first solder powder 101, so that the heat of the mother phase 104 in which the first solder powder 101 is melted during the solidification is obtained. Shrinkage can be mitigated by expansion during solidification of the second phase 105 in which the second solder powder 102 has melted. As a result, the occurrence of internal stress in the solder member is suppressed, and the occurrence of void defects can be prevented. In addition, since the second phase 105 is covered with the reaction control boundary film 103, there is no diffusion or alloying reaction between the mother phase 104 and the second phase 105. Physical properties such as wettability of each can be maintained.

According to this method of manufacturing a solder material, a paste-like solder material can be manufactured, and the manufactured solder material can be used to join a joint where solid solder material is difficult to dispose or to form a complex shape. It is suitable for use in joining members. In addition, since this solder material can be accurately injected even at a joint having a complicated shape, the reliability of soldering can be improved. Next, an example of a method for manufacturing the solder material 100 will be described.

First, a material for forming the reaction control boundary film 103 of the second solder powder 102 is selected, and the reaction control boundary film 103 is formed on the surface of the second solder powder 102 by an electroless plating method or the like. .

[0080] A predetermined amount of the second solder powder 102 coated with the reaction control boundary film 103 and a predetermined amount of the first solder powder 101 are uniformly mixed to form a mixture. Subsequently, a predetermined amount of a flux and a binder are mixed into the mixture, and the mixture is uniformly stirred to obtain a solder material 100.

According to this method of manufacturing a solder material, a force S for manufacturing a film-like or wire-like solder material can be obtained. By using this manufacturing method, it is possible to provide a solder material in an optimal form according to the application.

FIG. 9 shows that the solder material 100 obtained by the above-described method is applied between a first element member 111 formed of a flat plate and a second element member 112 formed of a flat plate having a concave portion on a joint surface. The joint member 110 is shown in a state of being disposed at the position shown in FIG. The joining member 110 is heated to a temperature equal to or higher than the melting point of the first solder powder 101 in, for example, the air or an inert gas atmosphere. The first solder powder 101 and the second solder powder 102 melted by the calorie heat undergo a cooling step to become a solder joint 120 having a cross-sectional shape as shown in FIG. The cross-sectional shape of the solder joint 120 shown in FIG. 10 shows the area indicated by A in FIG. 9 in detail.

[0083] As shown in FIG. 10, the second phase 105 in which the second solder powder 102 is melted and solidified is substantially uniformly dispersed in the mother phase 104 in which the first solder powder 101 is melted and solidified. . The surface of the second phase 105 is covered with the reaction control boundary film 103. In the joining using the solder material 100, when the mother phase 104 solidifies and subsequently contracts in the cooling process, the second phase 105 solidifies and expands, and the generation of internal stress in the solder joint 120 is suppressed. As a result, it is possible to prevent the occurrence of shrinkage cavities 122 occurring in the conventional solder joint 121 as shown in FIG. Further, in the mother phase 104, the physical properties such as the wettability of the first solder powder 101 constituting the mother phase 104 are maintained, so that the bonding surface of the first element member 111 and the second element member 112 is The bonding with the phase 104 can be performed optimally. Further, at the solder joint, the mechanical properties of the first solder powder 101 constituting the mother phase 104 are substantially reduced. The ability to maintain the swell.

According to this soldering method, the first solder powder 101 contains the second solder powder 102 having the property of expanding during solidification, thereby solidifying the mother phase 104 in which the first solder powder 101 is melted. The thermal shrinkage at the time can be alleviated by the expansion at the time of solidification of the second phase 105 in which the second solder powder 102 is melted. Thereby, the occurrence of internal stress in the solder member is suppressed, and the occurrence of void defects can be prevented. In addition, since the second phase 105 is covered with the reaction control boundary film, there is no diffusion or alloying reaction between the mother phase 104 and the second phase 105. And the physical properties such as wettability of the second phase 105 can be maintained. Thereby, the joining surface between the first element member 111 and the second element member 112 and the solder material can be optimally performed.

Next, another example of joining two members using the solder material 100 is shown in FIG.

[0086] In FIG. 12, the solder material 100 obtained by the above-described method is injected into the concave portion of the first element member 131 composed of a flat plate having a concave portion, and a bar-like shape is formed in the depth direction of the groove of the concave portion. 9 shows the joining member 130 with the second element member 132 inserted. The joining member 130 is heated to a temperature equal to or higher than the melting point of the first solder powder 101 in, for example, the air or an inert gas atmosphere. The first solder powder 101 and the second solder powder 102 that have been melted by heating are subjected to a cooling step to become a solder joint 140 having a cross-sectional shape as shown in FIG.

As shown in FIG. 13, the second phase 105 in which the second solder powder 102 has melted and solidified is substantially uniformly dispersed in the mother phase 104 in which the first solder powder 101 has melted and solidified. . The surface of the second phase 105 is covered with the reaction control boundary film 103. In the joining using the solder material 100, the second phase 105 solidifies and expands when the mother phase 104 undergoes thermal contraction in the solidification and subsequent cooling process, thereby suppressing the generation of internal stress in the solder joint 140. In addition, since the mother phase 104 forming the solder joint 140 maintains physical properties such as wettability of the first solder powder 101 forming the mother phase 104, the surface of the concave portion of the first element member 131 is maintained. The surface and the matrix 104 are optimally joined. Thereby, it is possible to prevent the occurrence of the peeling portion 151 from the surface of the concave portion of the first element member 131, which has occurred in the conventional solder joint 150 as shown in FIG. [0088] In the solder material, the method of manufacturing the solder material, and the method of soldering according to the second embodiment, the mother phase 104 contains a second phase 105 having a property of expanding when solidified. As it heat shrinks during solidification and subsequent cooling, the second phase 105 expands as it cools to the solidification temperature. As a result, the solidification shrinkage of the mother phase 104 can be reduced, and the generation of internal stress in the solder member is suppressed, and as a result, the occurrence of void defects such as shrinkage cavities 122 and peeled portions 151 is prevented. can do.

[0089] Further, since the second phase 105 is covered with the reaction control boundary film 103, there is no gap between the mother phase 104 and the second phase 105, and no diffusion or alloying reaction occurs. The mother phase 104 and the second phase 105 do not dissolve and form a eutectic alloy, for example. Therefore, in the mother phase 104, the physical properties of the first solder powder 101 forming the mother phase 104 are maintained, and in the second phase 105, the physical properties of the second solder powder 102 forming the second phase 105 are maintained. You. Further, at the solder joint, the mechanical properties of the first solder powder 101 constituting the mother phase 104 can be substantially maintained. In addition, the bonding surface between the first element member 111 and the second element member 112 and the solder material can be optimally performed.

[0090] In addition, since the solder material is made into a paste, the solder material can be easily used for joining at a joint where it is difficult to dispose a solid solder material or joining members having complicated shapes. . In addition, since this solder material can be injected accurately even at a joint having a complicated shape, the reliability of soldering can be improved.

[0091] In the above-described solder material 100, the force S indicating a paste-like configuration in which the first solder powder 101, the second solder powder 102, the flux and the binder are mixed, and the solder material which is not limited to this configuration, For example, a film configuration as shown in FIG. 15 and a wire configuration as shown in FIG. 16 may be used.

The solder materials 160 and 170 shown in FIG. 15 or FIG. 16 are manufactured, for example, as follows.

[0094] The predetermined amount of the second solder powder 102 coated with the reaction control boundary film 103 and the predetermined amount of the first solder The powder 101 is uniformly mixed with, for example, stirring to form a mixture. Subsequently, the mixture is filled in a mold, and the first solder powder 101 and the second solder powder 102 are fused together by pressing and heating to obtain a composite material.

Next, when a film-like solder material 160 as shown in FIG. 15 is formed, a composite material in which the first solder powder 101 and the second solder powder 102 are integrated, for example, Rolled to form a film-like solder material.

When forming a wire-like solder material 170 as shown in FIG. 16, a composite material in which the first solder powder 101 and the second solder powder 102 are integrated is, for example, pulled out. In addition, a wire-like solder material is formed. Further, as shown in FIG. 16, a flux 171 can be mixed along the central axis of the wire-shaped solder material 170.

[0097] As described above, the solder material is not limited to the paste-like configuration, but may be a solid configuration such as a film-like or wire-like configuration. Can be used.

Next, a specific example of the second embodiment will be described. In a specific embodiment described below, as shown in FIG. 12, a first element member 131 composed of a flat plate having a concave portion and a rod-shaped second element member 132 in the depth direction of the groove of the concave portion are provided. The following shows the case of joining in the inserted state.

[0099] (Example 4)

An electroless Ni plating film having a thickness of about 3 μm was formed on the surface of Sn—57% by weight81 powder having an average particle diameter of about 20 μm, and a second solder was manufactured. Subsequently, the second solder and the first solder having an average particle size of about 20 / im (Sn-0.7% by weight Cu powder) were mixed so that the content of the second solder was 15% by volume. In order to facilitate the removal and application of the oxide film on the surfaces of the first and second members and the formation of solder layers such as screen printing, an appropriate amount of flux was added to the composite solder. The adhesive was added to prepare a creamy composite solder.

[0100] Subsequently, a composite solder was filled into a concave portion having a diameter of 5 mm and a depth of 1 Omm formed on the surface of the first member made of oxygen-free Cu base. A rod-shaped second member having an outer diameter of 3 mm and made of an oxygen-free Cu base was inserted into the recess filled with the composite solder to a depth of about 7 mm. And In a state in which the second member is inserted into the concave portion of the first member,

Two

It was heated at a temperature of ° C for 3 minutes and soldered.

[0101] Each of the soldered first member and second member was fixed to a check of an Instron tensile tester, and the solder strength was measured and evaluated at a tensile speed of 0. ImmZs. As a result, the solder strength was 45 MPa. there were. In addition, as a result of inspecting the internal void defects of the solder layer using an ultrasonic flaw detector, accidental void defects due to impurities and others are 1% or less in terms of volume ratio, and void defects due to solidification shrinkage are reduced. Not detected at all.

[0102] (Example 5)

A second solder was manufactured by forming a 0.1 μm (7) Al 2 O 3 film on the surface of Sn—57 wt% 81 powder having an average particle diameter of about 20 × m by a sol-gel method. Then, this second solder

twenty three

The first solder consisting of Sn-0.7% by weight Cu powder with an average particle size of about 20 xm is mixed with the second solder so that the content of the second solder is 15% by volume to produce a composite solder material. did. Then, to facilitate the removal and application of the oxide film on the surfaces of the first and second members and the formation of a solder layer such as screen printing, an appropriate amount of flux and thickener are added to the composite solder, and a creamy A composite solder was prepared.

Subsequently, a composite solder was filled in a concave portion having a diameter of 5 mm and a depth of 1 Omm formed on the surface of the first member made of oxygen-free Cu base. A rod-shaped second member having an outer diameter of 3 mm and made of an oxygen-free Cu base was inserted into the recess filled with the composite solder to a depth of about 7 mm. Then, in a state where the second member is inserted into the concave portion of the first member, in the N gas atmosphere,

Two

It was heated at a temperature of ° C for 3 minutes and soldered.

[0104] Each of the soldered first member and second member was fixed to the check of an Instron tensile tester, and the solder strength was measured and evaluated at a tensile speed of 0. ImmZs. As a result, the solder strength was 28MPa. there were. In addition, as a result of inspecting the internal void defects of the solder layer using an ultrasonic flaw detector, accidental void defects due to impurities and others are 1% or less in terms of volume ratio, and void defects due to solidification shrinkage are reduced. Not detected at all.

(Example 6)

An about 0.1 μm thick SiO film was formed by the sol-gel method on the surface of Sn-22% by weight 31) powder with an average particle size of about 20 μm, and a second solder was manufactured. Then, this second

Two Then, the first solder consisting of Sn—2% by weight Cu—0.2% by weight Ag powder with an average particle size of about 20 μm is mixed so that the content of the second solder is 25% by volume. As a result, a composite solder material was manufactured. Then, to facilitate the removal and application of the oxide film on the surfaces of the first and second members and the formation of a solder layer such as screen printing, add an appropriate amount of flux and thickener to the composite solder, Was prepared.

Subsequently, a concave portion having a diameter of 5 mm and a depth of 1 Omm formed on the surface of the first member made of the oxygen-free Cu base was filled with a composite solder. A rod-shaped second member having an outer diameter of 3 mm and made of an oxygen-free Cu base was inserted into the recess filled with the composite solder to a depth of about 7 mm. Then, in a state in which the second member is inserted into the concave portion of the first member, 350

Two

It was heated at a temperature of ° C for 3 minutes and soldered.

[0107] Each of the soldered first member and second member was fixed to a check of an Instron tensile tester, and the solder strength was measured and evaluated at a tensile speed of 0.1 mmS. As a result, the solder strength was 40 MPa. there were. In addition, as a result of inspecting the internal void defects of the solder layer using an ultrasonic flaw detector, accidental void defects due to impurities and others are 2% or less in terms of volume ratio, and void defects due to solidification shrinkage are reduced. Not detected at all.

(Comparative Example 3)

A creamy composite solder was prepared by mixing Sn-3.5% by weight powder with an average particle size of about 20 μΐη, an appropriate amount of flux and a thickener.

Subsequently, a concave portion having a diameter of 5 mm and a depth of 1 Omm formed on the surface of the first member made of oxygen-free Cu base was filled with a composite solder. A rod-shaped second member having an outer diameter of 3 mm and made of an oxygen-free Cu base was inserted into the recess filled with the composite solder to a depth of about 7 mm. Then, in a state in which the second member is inserted into the concave portion of the first member, 350

Two

It was heated at a temperature of ° C for 3 minutes and soldered.

[0110] Each of the soldered first member and second member was fixed to a check of an Instron tensile tester, and the solder strength was measured and evaluated at a tensile speed of 0.1 mm. As a result, the solder strength was 20 MPa. there were. In addition, as a result of inspecting the internal void defect of the solder layer using an ultrasonic flaw detector, shrinkage cavities were generated at the intermediate position between the first and second members, which are the final solidified parts, and multiple coarse void defects were found. Was detected. The detected void defect is the volume fraction In conversion, it reached 12%.

[0111] It was revealed that the solder strength (20MPa) in Comparative Example 3 was 1/2 or less of the solder strength (45 MPa) in Example 4. It was also found that the void defect (volume ratio conversion: 12%) in Comparative Example 3 was about 12 times the void defect (volume ratio conversion: 1%) in Example 4.

[0112] These results show that the inclusion of the second solder consisting of Sn-57 wt% Bi with a coating on the surface in the first solder increases the solder strength, resulting in a very low rate of void defects. It was found that a solder material could be obtained. In addition, it has been clarified that the void defect is a cause of lowering the solder strength of the first member and the second member.

(Comparative Example 4)

A second solder composed of 81% Sn—57% by weight powder having an average particle diameter of about 20 μm and a first solder composed of Cu powder having an average particle diameter of 20 zm (7) Sn-0.7% by weight Mixing was performed so that the solder content was 15% by volume to produce a composite solder material. Then, an appropriate amount of flux and a thickener were added to this composite solder to prepare a creamy composite solder.

[0114] Subsequently, a concave portion having a diameter of 5 mm and a depth of 1 Omm formed on the surface of the first member made of the oxygen-free Cu base was filled with a composite solder. A rod-shaped second member having an outer diameter of 3 mm and made of an oxygen-free Cu base was inserted into the recess filled with the composite solder to a depth of about 7 mm. Then, in a state where the second member is inserted into the concave portion of the first member, in the N gas atmosphere,

Two

It was heated at a temperature of ° C for 3 minutes and soldered.

[0115] Each of the soldered first member and second member was fixed to a check of an Instron tensile tester, and the solder strength was measured and evaluated at a tensile speed of 0.1 mm / s. It was 20 MPa. In addition, as a result of inspecting the internal void defect of the solder layer using an ultrasonic flaw detector, shrinkage cavities were generated at the intermediate position between the first and second members, which are the final solidified parts, and multiple coarse void defects were found. Was detected. The number of detected void defects reached 10% by volume ratio.

[0116] It was revealed that the solder strength (20MPa) in Comparative Example 4 was about 30% lower than the solder strength (28 MPa) in Example 5. In addition, the void defect (10% by volume ratio) in Comparative Example 4 is 10 times as large as the void defect (1% by volume ratio) in Example 4. It was also clear that it was.

[0117] From these results, as shown in Example 5, by having a film on the surface of the second solder, it is possible to obtain a solder material having a high solder strength and having a very low void defect generation rate. I understood. In addition, by having a film on the surface of the second solder, the alloying reaction between the first solder and the second solder is prevented, and the solidification and expansion properties characteristic of the second solder are maintained. It turned out that the effect can be fully exhibited. Furthermore, it became clear that void defects were the cause of the decrease in the solder strength of the first and second members.

[0118] Here, the measurement results of the above Examples and Comparative Examples are summarized in Table 2.

[Table 2]

(Third Embodiment)

Hereinafter, the third embodiment will be described in the order of the composition of the lead-free solder, the shape of the lead-free solder, and the method of soldering the lead-free solder.

[0120] (Composition of lead-free solder)

The lead-free solder according to the third embodiment is composed of Sn-containing alloy containing Sn or Pb containing 0.02-2.0% by weight of Co.

[0121] The content of Co contained in Sn or Sn-based alloy is appropriately set in the range of 0.02 to 2.0% by weight depending on the obtained mechanical properties and melting point. Here, if the content of Co is less than 0.02% by weight, sufficient mechanical properties may not be ensured. Temperature limits may be exceeded. Furthermore, more preferable range ί for the content of Co contained in the Sn or Sn-based alloy or a 0. 05-1. 0 wt ^_0/0. Further, the Co to Sn 0 · 02-2. 0 in a range of weight ^_0/0 The solidus of the lead-free solder contained is 229 ° C, and the liquidus is 229 ° C-500 ° C.

[0122] Here, the Sn-based alloy is at least one of Ag, Al, Au, Bi, Co, Cr, Cu, Fe, Ge, In, Mg, Mn, Pd, Si, Sr, Te, and Zn , The balance consisting of Sn and unavoidable impurities, and a low melting point Sn alloy with a melting point in the range of 117-350 ° C.

[0123] For example, as such a low-melting Sn-based alloy, 111: 52% by weight, balance: Sn and Sn alloy (melting point 117 ° C) composed of unavoidable impurities, 857% by weight, balance: Sn and unavoidable Sn alloy composed of impurities (melting point: 139 ° C), Δ! 1: 9% by weight, balance: Sn and Sn alloy composed of unavoidable impurities (melting point: 198 ° C), Cu: 4.5% by weight, balance: Examples include Sn and Sn alloys consisting of unavoidable impurities (solidus 227 ° C, liquidus 350 ° C).

[0124] Thus, the Sn or Sn-based alloy, a Co 0. 02-2. 0 wt ^_0/0 By containing, Sn or reduces the surface tension of the Sn-based alloy, improving the wettability Can be done. Furthermore, by suppressing the reaction between the member to be soldered and Sn or Sn-based alloy, and suppressing the growth of intermetallic compounds at the bonding interface, the aggregation of molten solder is suppressed and the wettability is improved. Power S can.

[0125] The lead-free solder may contain 0.0-2.0% by weight of Co and 0.02-7.5% by weight of Cu, with the balance being Sn and unavoidable impurities. .

[0126] Co and Cu contained in the lead-free solder are appropriately set within the range of the above content depending on the required mechanical properties, melting point, and the like. Here, if the content of Co is less than 0.02% by weight, sufficient mechanical properties may not be secured. Exceed the allowable temperature limit of the force S. If the Cu content is less than 0.02% by weight, sufficient mechanical properties may not be ensured. If the Cu content is more than 7.5% by weight, the melting point becomes high, and element components Temperature limits may be exceeded. The more preferable range of the Co content in Sn is 0.1-0.5% by weight, and the more preferable range of the Cu content is 0.5-1.0% by weight / ⁰ . It is ₀ . Also, Sn, since the Co 0. 02-2. 0 wt ^_0/0 and Cu of 0.02 7.5 wt% of lead-free solder liquidus containing in the range is 229- 500 ° C, An appropriate liquidus can be obtained by a combination of alloy compositions.

[0127] Thus, Sn containing 0.02-2.0% by weight of Co and 0.02-7.5% by weight of Cu are contained. By having this, the solder strength can be further improved in addition to the effect of the lead-free solder containing no Cu described above.

[0128] Furthermore, the lead-free solder contains 0.02-2.0% by weight of Co, Sn or Pb-free alloy, Sn-based alloy, or 0.02-2.0% by weight of Co, Cu 0.02-7. Even if it is composed of a first solder containing 5% by weight, the balance being Sn and unavoidable impurities, and a second solder consisting of a Sn-based alloy containing no Sn or Pb.

[0129] Here, the first solder is a Sn-based alloy that contains 0.0 to 2.0% by weight of the above-mentioned Co, does not contain Sn or Pb, is a lead-free solder, or contains 0.02% of Co. 2.0% by weight, Cu

02-7. It is the same as a lead-free solder containing 5% by weight, with the balance being Sn and unavoidable impurities. The second solder is made of a Sn-based alloy containing no Sn or Pb, and may contain unavoidable impurities.

[0130] Further, the first solder and the second solder can be formed, for example, into spherical or irregular shaped powder, finolem, or the like. Further, the first solder and the second solder having a powder shape can be used in the form of a paste mixed with, for example, a flux or a binder.

[0131] When the first solder and the second solder are mixed in advance and used, the mixing ratio can be appropriately set according to the required mechanical properties, melting point, and the like. For example, by adjusting the content of Co contained in the first solder within the range of 0.02-2. 0% by weight, the wettability is improved by containing Co, and the growth of intermetallic compounds at the joint interface is suppressed. The mixing ratio between the first solder and the second solder is set so as to maintain the ratio. Also, the first solder and the second solder can be laminated and used without being mixed in advance.

[0132] Thus, the configuration of Sn or Sn-based alloy, a first solder the 0. 02-2. 0 wt ^_0/0 containing Co, a lead-free solder in the second solder consisting of Sn or Sn-based alloy By doing so, the surface tension of Sn or Sn-based alloy can be reduced, and the wettability can be improved. Furthermore, by suppressing the reaction between the covered member and Sn or Sn-based alloy, and by suppressing the growth of intermetallic compounds at the joint interface, the aggregation of molten solder is suppressed and the wettability is improved. Power S can. Further, the Co 0. 02-2. 0 weight ^_0/0 containing Sn, by containing 0.5 02-7. 5 by weight% of Cu, in addition to the effect of the lead-free solder containing no Cu described above , Further In addition, the solder strength can be improved.

[0133] (Shape of lead-free solder)

The shape of the lead-free solder having the above composition will be described with reference to FIGS. 17-20.

FIG. 17 is a perspective view of a lead-free solder formed in a film shape, and FIG. 18 is a cross-sectional view of a lead-free solder formed in a cost shape. FIG. 19 is a perspective view of a lead-free solder formed in a wire shape, and FIG. 20 is a perspective view of a lead-free solder formed in a rod shape.

[0135] First, the film-shaped lead-free solder 200 formed in the film shape shown in Fig. 17 will be described.

[0136] The film-shaped lead-free solder 200 is formed by rolling a plate-shaped lead-free solder into a film by, for example, rolling. The thickness of the film-shaped lead-free solder 200 is preferably in the range of 20 200 / m. If the thickness force is less than 20 / m, it is difficult to obtain sufficient bonding strength. If it is more than 200 / m, the thermal conductivity and electrical conductivity decrease. The plate-shaped lead-free solder can also be formed by filling lead-free solder having a powder shape into a mold having a predetermined shape, and applying pressure and heat. Further, it can be formed by rolling directly from powder.

[0137] In addition, the above-mentioned first solder comprising Sn-Pb and not containing Sn or Pb containing 0.02-2.0% by weight of Co, and the first solder comprising Sn or Sn-based alloy force 2 By laminating each solder and rolling it into a film by, for example, rolling, etc., one side is composed of the first solder and the other side is composed of the second solder. The film-shaped lead-free solder 200 to be formed can also be formed. The first solder contains 0.0-2.0% by weight of Co and 0.02-7.5% by weight of Cu, with the balance being Sn and unavoidable impurities. May be used.

[0138] When the first solder and the second solder are stacked to form the film-shaped lead-free solder 200, the first solder and the second solder to be stacked have a shape such as a film or a powder. Can be taken. Here, when the first solder and the second solder are formed of spherical or irregular-shaped powder, the average particle diameter of the powder is preferably in the range of 25 to 50 xm. If the average particle size is less than 25 μΐη, the yield is poor and it is uneconomical. If the average particle size is more than 50 / m, it is difficult to control the solder thickness.

Next, the paste-like lead-free solder 210 shown in FIG. 18 will be described.

[0140] This paste-like lead-free solder 210 is formed by mixing a lead-free solder 220 having a spherical or irregular powder shape with a flux 221 and a binder 222.

[0141] The flux 221 removes an oxide film between the solder and a member joined with the solder, and prevents the solder from being oxidized again during heating. As the flux 221, a commonly used activator such as an amine halide salt or an organic acid is used, but is not limited to these, and any commonly used activator can be used. . The content of the flux 221 in the paste-like lead-free solder 210 can be set appropriately in the range of 10 15 weight ^_0/0. When the content of the flux 221 is less than 10% by weight, the effect of removing the oxide film between the solder and the member joined with the solder material is small, and the effect of preventing the re-oxidation during the heat of caro is small. If the content is more than 15% by weight, the effect cannot be expected to be improved, and the residue increases.

[0142] Further, the content of the solid content in the flux 221 can be appropriately set within a range of 30 to 60% by weight. If the solid content is less than 30% by weight, the adhesion of the solder material applied or printed on the surface of the component parts will be insufficient. This is because a void defect is likely to occur at the joint.

[0143] The average particle size of the lead-free solder 220 having a spherical or irregular powder shape is 25-50.

The range / im is preferred. When the average particle size is less than 25 / im, the yield is poor and uneconomical, and when the average particle size is more than 50 x m, it is difficult to control the thickness of the solder, which is difficult.

[0144] Next, the wire-shaped lead-free solder 230 formed in a wire shape shown in Fig. 19 will be described.

[0145] The wire-shaped lead-free solder 230 is formed by, for example, drawing out a member made of lead-free solder. Further, the wire-shaped lead-free solder 230 can also be formed by filling a lead-free solder having a powder shape into a mold having a predetermined shape, and applying pressure and heat. further, The wire-shaped lead-free solder 230 can also be formed by pouring molten lead-free solder into a mold having a predetermined shape and then cooling it.

[0146] Next, the rod-shaped lead-free solder 240 formed in a rod shape shown in Fig. 20 will be described.

[0147] The rod-shaped lead-free solder 240 formed in a rod shape shown in Fig. 20 is formed by filling a lead-free solder having a powder shape into a mold having a predetermined shape, and pressing and heating. . Further, the rod-shaped lead-free solder 240 can also be formed by pouring a molten lead-free solder into a mold having a predetermined shape and then cooling it.

[0148] As described above, the lead-free solder can take a shape such as a film shape, a paste shape, a wire shape, and a rod shape, and the lead-free solder having an optimal form should be used according to the application in which the lead-free solder is used. Can be. In addition, the shape of the lead-free solder is not limited to the above-mentioned shape, and can be formed by appropriately changing the shape according to the application.

[0149] Here, an example of a method of forming lead-free solder into a spherical or irregular shaped powder will be described.

[0150] First, a lead-free solder is heated and melted.

2 Fine atomization by atomizing method using inert gas such as gas, Ar gas, N / Ar mixed gas, etc.

Two

Granulate and solidify. In the atomization method, a molten mixture is injected from a nozzle at a subsonic or supersonic speed together with an inert gas, and the molten mixture is atomized by a jet stream of the inert gas. Then, from the atomized lead-free solder powder, a powder having an average particle diameter in a predetermined range is selected using, for example, a sieve.

[0151] The atomized and solidified lead-free solder powder has a smaller average particle diameter when the jet flow rate of the inert gas injected from the nozzle is higher. In particular, when the jet stream reaches a supersonic state of about 23 times the sound velocity, for example, the effect of atomization by the shock wave is added, and the average particle diameter of the powder can be further reduced. Further, since the inert gas is used as the jet stream, oxidation on the surface of the powder can be suppressed. Air or water can be used in place of the inert gas.However, when air or water is used, the effect of suppressing the oxidation of the powder surface is small. It is preferable to use an inert gas for the jet stream because the body shape is unlikely to be spherical. [0152] (Solderless soldering method)

Next, the method of soldering lead-free solder will be described with reference to FIGS. 21 and 22.

FIG. 21 shows a sectional view of first element member 250 and second element member 251 joined by lead-free solder 220. FIG. 22 is a cross-sectional view of the first element member 250 and the second element member 251 joined by the two types of lead-free solders 252 and 253.

In the soldering method shown in FIG. 21, lead-free solder 220 is arranged between first element member 250 and second element member 251. Then, this is heated to a temperature equal to or higher than the melting point of the lead-free solder 220, for example, in the air or in an inert gas atmosphere. The lead-free solder 220 melted by heating is subjected to a cooling process to become a solder joint having a sectional shape as shown in FIG. As the lead-free solder 220 used here, a lead-free solder having a shape such as a film, a paste, a wire, and a powder described above can be used.

[0155] Further, in the soldering method shown in Fig. 22, the first solder 252 comprising Sn described above containing 0.0 to 2.0% by weight of Co and containing no Sn or Pb, and A second solder 253 made of Sn or Sn-based alloy is laminated, and the laminated solder is arranged between the first element member 250 and the second element member 251. Then, this is heated to a temperature equal to or higher than the melting point of the lead-free solder, for example, in the air or in an inert gas atmosphere. The first solder 252 and the second solder 253 that have been melted by heating are subjected to a cooling process to become solder joints having a cross-sectional shape as shown in FIG. The first solder 252 contains 0.02-2.0% by weight of Co and 0.02-7.5% by weight of Cu, with the balance being Sn and unavoidable impurities. Use solder.

In this joint, the first element member 250 is joined with the first solder 252, and the second element member 251 is shown with a structure in which the second solder 253 is joined. The order in which the second solder 252 and the second solder 252 are stacked is set as appropriate.

[0157] The use of the lead-free solder is not limited, but, for example, bonding of an electronic component to a substrate that requires thermal conductivity, wettability, mechanical strength, and the like, and bonding of the electronic components to each other. It is preferably used for bonding or the like. Here, the first element member 250 is, for example, a substrate of an electronic component. The second element member 251 can be formed of, for example, an electronic component such as a chip component. Then, these substrates and electronic members can be joined with the first solder 252 and the second solder 253, the lead-free solder 220, and the like. Further, the first solder 252, the second solder 253, and the lead-free solder 220 can be used for a wire bond and the like in addition to such a die bond.

[0158] As described above, the first and second solders 252 and 253 and the lead-free solder 220 containing Co in an amount of 0.02-2.0% by weight were used for joining the first element member 250 and the second element member 251. By using, the surface tension of Sn or a Sn-based alloy can be reduced, and the wettability can be improved. Furthermore, by suppressing the reaction between the first element member 250 and the second element member 251 and Sn or a Sn-based alloy, and suppressing the growth of intermetallic compounds at the joint interface, the aggregation of the molten solder is suppressed. , The wettability can be improved. As a result, generation of void defects is suppressed, and a solder joint having excellent thermal conductivity, mechanical strength, and the like can be obtained.

Next, a specific example of the third embodiment will be described.

[0160] (Example 7)

Sn-0.7% by weight 01-0.2% by weight Lead-free solder consisting of 0 was melted to produce an ingot having a thickness of 30 mm, a width of 100 mm and a length of 200 mm. Next, the ingot was rolled to produce a film-shaped solder having a thickness of 0.1 lm and a width of 100 mm. Next, as shown in FIG. 23, a film-like solder 262 having a thickness of 0.1 mm, a width of 50 mm and a length of 50 mm was placed between two copper plates 260 and 261 having a thickness of 3 mm, a width of 50 mm and a length of 100 mm. installed. Subsequently, in a nitrogen gas atmosphere, heating was performed at a temperature of 300 ° C. for 5 minutes to perform soldering.

[0161] As a result of performing a shear test on the soldered joint at a tensile speed of 0.1 mm / min, the shear strength was 38 MPa.

[0162] Further, the surface tension γ of a lead-free solder composed of Sn-0.7% by weight〇11-0.2% by weight〇0, which was heated and melted in a nitrogen gas atmosphere, was measured by a dropping method. In this enemy law, the circle

L

The surface tension is measured by taking advantage of the property that the weight of the droplet dropped from the mouth of the shape drops overcoming the surface tension.

As shown in FIG. 24, the lead-free solder 265 composed of molten Sn—0.7% by weight〇11−0.2% by weight〇0 is supplied to the nose 266 having an inner diameter of 0.3 mm. And the tip of Noznore 266 A droplet of the lead-free solder 265 was formed on the substrate and dropped when the droplet reached a predetermined weight. Here, the neck diameter (L) of the lead-free solder 265 immediately before falling from the nozzle 266 and the weight (mg) of the dropped droplet were measured.

[0164] Here, according to the sub-enemy method, when the mass of one droplet is m, the force pulling the droplet downward (the weight of the droplet) (mg) is the surface tension (γ) immediately before falling. From the relationship that is equal to

L

The formula holds.

7 = mg 2

L Z u L… formula (1

[0165] The surface tension ( _Ί ) of the lead-free solder 110 is calculated by substituting the constriction diameter (U and the weight (mg) of the dropped droplet) of the lead-free solder 110 immediately before falling into the equation (1). Result

L

The surface tension (γ) was 0.36 NZm.

L

[0166] The relationship between the surface tension (γ) and the wettability is such that the smaller the surface tension (γ), the better the wettability.

L L

It will be excellent.

[0167] Furthermore, an X-ray microanalyzer (EPMA; Electron Probe Micro-Analysis) was used to perform elemental analysis on the cross sections of the copper plates 260 and 261 joined with the film-like solder 262. The results of the elemental analysis are shown in FIGS. 25A and 25B. 25A and 25B show the results on one copper plate 260.

From this measurement result, as shown in FIG. 25A, the solder layer 271 bonded to the copper plate 260 via the bonding surface 270 is the first layer formed on the portion of the solder layer 271 facing the bonding surface 270. It can be seen that the second solder layer 271b is formed mainly from the solder layer 271a and the second solder layer 271b formed on the side opposite to the joint surface 270 side of the first solder layer 271a. The first solder layer 271a is formed relatively flat along the joint surface 270 without causing significant undulations on the second solder layer 271b side.

Subsequently, when an elemental analysis of Sn was performed on this cross section, the concentration of Sn contained in the first solder layer 271a was lower than the concentration of Sn contained in the second solder layer 271b. In addition, when Cu elemental analysis was performed on this cross section, the concentration of Cu contained in the first solder layer 271a was higher than the concentration of Cu contained in the second solder layer 271b. Further, when elemental analysis of Co is performed on this cross section, as shown in FIG. 25B, a region 272 where the Co concentration is high along the bonding surface 270 is particularly formed on the first solder layer 271a, particularly on the bonding surface 270 side. Were present. [0170] From the above results, the first solder layer 271a has a higher η (Sn Cu: Sn43.5—45.5 atomic%)

5 6

It was found that the eutectic structure was mainly formed of an intermetallic compound layer composed of Sn-Cu-Co that contained more Co than the second solder layer of 27 lb. In particular, it was found that a region 272 having a high Co concentration was unevenly distributed along the bonding surface 270 on the bonding surface 270 side of the intermetallic compound layer. Further, it was found that the second solder layer 271b was mainly formed of the lead-free solder used.

[0171] (Example 8)

A lead-free solder consisting of Sn-0.7 wt% 〇11-2 wt% 〇0 was melted to produce an ingot having a thickness of 30 mm, a width of 10 Omm and a length of 200 mm. Next, the ingot was rolled to produce a film-like solder having a thickness of 0.1 mm and a width of 100 mm. Next, as shown in FIG. 23, a film-like solder 262 having a thickness of 0.1 mm, a width of 50 mm, and a length of 50 mm was placed between two copper plates 260, 261 having a thickness of 3 mm, a width of 50 mm, and a length of 100 mm. installed. Subsequently, in a nitrogen gas atmosphere, heating was performed at a temperature of 300 ° C. for 5 minutes to perform soldering.

[0172] A shear test at a tensile speed of 0.1 mm / min was performed on the soldered joint to find that the shear strength was 42 MPa.

[0173] Further, the same method as the method for measuring the surface tension (γ) shown in Example 7 was used to measure

L

The result of calculating the surface tension (γ) of the lead-free solder consisting of -0.7% by weight〇11-1% by weight〇0

L

The surface tension (γ) was 0.35 N / m.

L

Further, an X-ray microanalyzer (EPMA; Electron Probe Micro-Analysis) was used to perform an elemental analysis on the cross sections of the copper plates 260 and 261 joined with the film-like solder 262.

As a result, although not shown, a result similar to the result shown in FIGS. 25A and 25B of Example 7 could be obtained. That is, using the reference numerals shown in FIGS. 25A and 25B, the solder layer 271 joined to the copper plate 260 via the joint surface 270 is formed at a portion of the solder layer 271 facing the joint surface 270. The first solder layer 271a and the second solder layer 271b formed on the side opposite to the joint surface 270 side of the first solder layer 271a were found to be mainly formed. Also, the first solder layer 271a was formed relatively flat along the joint surface 270 without causing significant undulation on the second solder layer 271b side. [0176] Summarizing the results of the elemental analysis, the first solder layer 271a shows that η (Sn Cu: Sn 43.5—45

5 6

(5 atomic%) was found to be mainly formed by an intermetallic compound layer composed of Sn-Cu-Co containing Co in the eutectic structure more than the second solder layer 271b. In particular, it was found that a region 272 having a high Co concentration was unevenly distributed along the bonding surface 270 on the bonding surface 270 side of the intermetallic compound layer. Also, it was found that the second solder layer 271b was mainly formed of the lead-free solder used.

(Example 9)

A lead-free solder consisting of Sn-0.7% by weight 〇11-0.02% by weight〇0 was melted to produce an ingot having a thickness of 30 mm, a width of 100 mm and a length of 200 mm. Next, the ingot was rolled to produce a film solder having a thickness of 0.1 mm and a width of 100 mm. Next, as shown in Fig. 23, a film with a thickness of 0.1 mm, a width of 50 mm, and a length of 50 mm is placed between two identical plates 260, 261 with a thickness of 3 mm, a width of 50 mm and a length of 100 mm. Solder 262 was installed. Subsequently, in a nitrogen gas atmosphere, heating was performed at a temperature of 300 ° C. for 5 minutes to perform soldering.

[0178] The soldered joint was subjected to a shear test at a tensile speed of 0.1 mm / min, and as a result, the shear strength was 32 MPa.

[0179] In addition, the same method as the method for measuring the surface tension (γ) shown in Example 7 was used to determine whether the molten Sn

L

-0.7% by weight 01- 0.02% by weight 〇0 The surface tension (γ) of the lead-free solder was calculated.

L

As a result, the surface tension (γ) was 0.38 N / m.

L

[0180] Further, an X-ray microanalyzer (EPMA; Electron Probe Micro-Analysis) was used to perform elemental analysis on the cross sections of the copper plates 260 and 261 joined by the film solder 262.

As a result, although not shown, a result similar to the result shown in FIGS. 25A and 25B of Example 7 could be obtained. That is, using the reference numerals shown in FIGS. 25A and 25B, the solder layer 271 joined to the copper plate 260 via the joint surface 270 is formed at a portion of the solder layer 271 facing the joint surface 270. The first solder layer 271a and the second solder layer 271b formed on the side opposite to the joint surface 270 side of the first solder layer 271a were found to be mainly formed. Also, the first solder layer 271a was formed relatively flat along the joint surface 270 without causing significant undulation on the second solder layer 271b side. [0182] Summarizing the results of the elemental analysis, the first solder layer 271a shows that η (SnCu: Sn43.5—45

5 6

[0183] (Comparative Example 5)

A lead-free solder consisting of Sn-0.7% by weight of about 11 was melted to produce an ingot having a thickness of 30 mm, a width of 100 mm and a length of 200 mm. Next, the ingot was rolled to produce a film solder having a thickness of 0.1 mm and a width of 100 mm. Next, as shown in Fig. 23, a film-like solder 262 having a thickness of 0.1 mm, a width of 50 mm, and a length of 50 mm is placed between two copper plates 260, 261 having a thickness of 3 mm, a width of 50 mm, and a length of 100 mm. installed. Subsequently, soldering was performed in a nitrogen gas atmosphere at a temperature of 300 ° C for 5 minutes.

[0184] A shear test was performed on the soldered joint at a tensile speed of 0.1 mm / min. As a result, the shear strength was 28 MPa.

[0185] In addition, the same method as the method for measuring the surface tension (γ) shown in Example 7 was used to determine whether the molten Sn

L

The surface tension (γ) of the lead-free solder consisting of -0.7% by weight 〇11 was calculated.

L

γ) was 0.41 N / m.

L

[0186] Further, an X-ray microanalyzer (EPMA; Electron Probe Micro-Analysis) was used to perform elemental analysis on the cross sections of the copper plates 260 and 261 joined by the film solder 262. FIG. 26 shows the result of the elemental analysis. FIG. 26 shows the result on one copper plate 260.

[0187] From this measurement result, as shown in FIG. 26, the solder layer 281 bonded to the copper plate 260 via the bonding surface 280 was formed at the portion of the solder layer 281 facing the bonding surface 280. It can be seen that the first solder layer 281a and the second solder layer 281b formed on the side opposite to the bonding surface 280 of the first solder layer 281a are mainly formed. Also, the first solder layer 28 la vigorously undulates on the second solder layer 281b side. Also, the height of the first solder layer 281a protruding toward the second solder layer 281b is equal to that of the first solder layer 271a shown in the seventh embodiment. In many cases, it is about 2-3 times larger. Although not shown in the other examples, the same results as in Example 7 were obtained in the other examples, so that the height of the first solder layer 281a protruding toward the second solder layer 281b was reduced. It can be said that there are many parts that are about 23 times as large as those of the first solder layers of Examples 8 and 9.

[0188] Subsequently, when the elemental analysis of Sn was performed on this cross section, the concentration of Sn contained in the first solder layer 281a was lower than the concentration of Sn contained in the second solder layer 281b. In addition, when the elemental analysis of Cu was performed on this cross section, the concentration of Cu contained in the first solder layer 281a was higher than the concentration of Cu contained in the second solder layer 281b.

[0189] From the above results, the first solder layer 281a has a thickness of η (Sn Cu: Sn43.5—45.5 at%).

5 6

It was found that it was mainly formed of an intermetallic compound layer having a eutectic structure. Also, it was found that the second solder layer 281b was mainly formed of the lead-free solder used.

[0190] Comparing the measurement result of Comparative Example 5 with the measurement result of Example 7-9, the lead-free solder containing Co at a predetermined content in Example 7-9 does not contain Co. It was found that the surface tension in the molten state was smaller and the wettability was superior to that of a lead-free solder consisting of Sn-0.7% by weight〇11.

[0191] In addition, as a result of a shear test, the lead-free solder containing Co in Example 7-9 at a predetermined content rate showed a higher shear strength than the lead-free solder consisting of Sn-0.7 wt% 01 without Co. The strength was found to be high.

[0192] From the results of elemental analysis, it was found that in the lead-free solder containing Co at a predetermined content in Examples 7-9, the unevenness of the intermetallic compound layer formed along the bonding surface 270 was small and flat. On the other hand, in the case of a lead-free solder containing 0.7% by weight of Sn, which does not contain Co, the undulation of the intermetallic compound layer is severe. In the case of lead-free solder containing a certain amount of, the height of the undulation was about 2-3 times higher.

[0193] Furthermore, in the lead-free solder containing Co at a predetermined content rate in Example 79, a region 272 having a high Co concentration 272 along the joint surface 270 is formed on the joint surface 270 side of the first solder layer 271a. It was found to be unevenly distributed.

[0194] From the above comparison, it was found that the lead-free solder containing Co in Example 79 with a predetermined content ratio was found. In addition, by containing Co, the surface tension can be suppressed and the wettability can be improved. In addition, the intermetallic structure having a eutectic structure of η (Sn Cu: Sn43.5—45.5 at%) Compound layer

5 6

It was found that formation and growth could be suppressed. As a result, it was found that the solder joint strength was improved.

(Fourth Embodiment)

Hereinafter, the oxidation-resistant solder according to the fourth embodiment will be described.

[0196] Oxidation-resistant solder forms at least one metal selected from the group consisting of Cu, Ag, Au or VIII, an iron-group metal of Co and Ni, which forms a eutectic alloy with Sn as the main component. Containing 0.02 to 12% by weight of the first subcomponent consisting of Mn, Pd, and Pt, which form a solid solution alloy with the first subcomponent of the parentheses and do not form a solid solution alloy with the main component Sn. It contains 0.02.1.2% by weight of the selected second secondary component consisting of at least one metal, and the balance consists of Sn and unavoidable impurities.

[0197] The content of the first auxiliary component with respect to the whole oxidation-resistant solder may be the eutectic composition of Sn as the main component and the metal as the first auxiliary component or near the eutectic composition. It is set appropriately according to the mechanical properties and melting point required for the product. For example, in the case where Cu is the first auxiliary component, Ag, Au, Co, Ni are contained each alone, each first auxiliary component is Cu:. 0. 02-1 2 wt ^_0/0, Ag : 3. 0-4 0 weight ^{_{0/0, Au:. 9.}} 0- 12. 0 wt ^{_{0 / o, Co: 0. 0}} 2- 1. 0 wt%, Ni:. 0. 02-0 6 weight %. When a plurality of components of the first subcomponent are contained in combination, the content of the first subcomponent in the whole oxidation-resistant solder is preferably set appropriately within a range of 0.02 to 12% by weight. . If the content of the first subcomponent is less than the above-mentioned predetermined range, sufficient mechanical properties cannot be secured, and if it is too large, the melting point may exceed the allowable temperature limit of the component.

[0198] The content of the second auxiliary component in the entire oxidation-resistant solder is appropriately set according to the mechanical properties and melting point required for the oxidation-resistant solder. For example, when each of the second subcomponents, Mn, Pd, and Pt, is contained alone, each of the second subcomponents contains Mn: 0.02-1.2% by weight, Pd: 0.02-0. 6% by weight, Pt: contained in the range of 0.02 to 0.6% by weight. When a plurality of the second subcomponents are contained in combination, the content of the second subcomponent in the entire oxidation-resistant solder is appropriately set within a range of 0.02 to 1.2% by weight. Is preferred. If the content of the second auxiliary component is less than the above-mentioned predetermined range, a sufficient effect of suppressing the formation of oxides in the intermetallic compound cannot be obtained, and if it is too large, the melting point is high and the material cost increases.

[0199] Further, the oxidation-resistant solder is preferably a spherical or irregular-shaped powder, and the average particle diameter thereof is preferably in the range of 110 µm. If the average particle size of the oxidation-resistant solder is less than 1 μm, an oxidation-resistant solder having a uniform structure with a fast cooling rate can be obtained.However, in the soldering process, a solder layer with a predetermined thickness is formed. It takes a long time to complete the process. If the average particle size of the oxidation-resistant solder exceeds 100 zm, it may be difficult to appropriately adjust the thickness of the solder layer.

[0200] According to this oxidation-resistant solder, by forming a solid solution with the second subcomponent, the metal of the first subcomponent is trapped in the second subcomponent, and the free first component bonded to Sn of the main component is formed. The minor metal content is reduced. As a result, it has an electrochemically lower reduction potential and suppresses the formation of oxides in the intermetallic compound, thereby improving the heat conduction characteristics and further improving the solder strength, especially the heat resistance. Fatigue strength can be significantly improved. Further, in the oxidation-resistant solder, the generation of oxides in the intermetallic compound can be suppressed, so that the wettability can be improved.

Next, an example of a method for producing an oxidation-resistant solder will be described.

[0202] First, a mixture of the first subcomponent metal, the second subcomponent metal, and Sn mixed at a predetermined ratio is heated and dissolved. Subsequently, the melted mixture is poured into a mold, cooled and solidified. The cooling rate of the mixture in this cooling step is about 10 ° C./sec. In this case, a mold having a water cooling function may be used as the mold. In this case, the cooling rate of the mixture is about 100 ° C.Z seconds, and an oxidation-resistant solder having a more uniform composition can be obtained. Further, the oxidation-resistant solder can be formed as a foil by rolling or the like.

[0203] According to this method for producing an oxidation-resistant solder, the melted liquid phase mixture is rapidly solidified at a cooling rate of 10 ° C / sec or more, so that the oxidation-resistant solder having a uniform composition without solidification segregation occurs. Solder can be obtained.

[0204] The oxidation-resistant solder can also be manufactured by the following manufacturing method.

First, the first auxiliary component metal, the second auxiliary component metal, and the Sn The resulting mixture is heated and dissolved. Subsequently, an oxidation-resistant solder powder may be produced by the atomizing method described in the third embodiment.

[0206] In the atomization method using an inert gas described in the third embodiment, the atomized powder is cooled at a cooling rate on the order of 103 to 105 ° C / sec, so that solidification segregation occurs. Oxidation-resistant solder having a uniform composition can be obtained without causing cracks.

[0207] Next, a soldering method using the oxidation-resistant solder obtained by the above-described method for producing an oxidation-resistant solder will be described with reference to FIGS. 27A, 27B, 27C, 27D, and 27E. I do. FIGS.27A, 27B, 27C, 27D, and 27E show a process of soldering the first element member 300 and the second element member 301 formed of flat plates with the oxidation-resistant solder 302. I have.

First, oxide film 303 formed on the soldering surfaces of first element member 300 and second element member 301 is removed (see FIGS. 27A and 27B). The oxide film 303 is formed, for example, by shot blasting or air blasting on the first element member 300 and the second element member 301 at a speed of several m / s to several tens m / s together with air or an inert gas. It can be removed by colliding with the soldering surface. For example, abrasives such as steel, SiC, Al O

Preferably, the particles are spherical particles. The average particle size of the abrasive is appropriately selected according to the required surface roughness. Generally, the range of 範囲 μΐη—50μ—η is preferable. The oxide film 303 can also be chemically removed by immersing the soldering surfaces of the first element member 300 and the second element member 301 in an etchant.

Subsequently, the powder of the oxidation-resistant solder 302 is uniformly placed on the soldering surface of the first element member 300 from which the oxide film 303 has been removed (see FIG. 27C). Then, the second element member 301 is stacked on the first element member 300 on which the powder of the oxidation-resistant solder 302 is installed, with the soldering surface of the second element member 301 facing down (see FIG. 27D). The laminated member thus laminated is heated to a temperature equal to or higher than the melting point of the oxidation-resistant solder 302, for example, in the air or in an inert gas atmosphere. The powder of the oxidation-resistant solder 302 melted by heating becomes a solder joint 304 having a cross-sectional shape as shown in Fig. 27Ε through a cooling process.

[0210] The second soldering method has an electrochemically lower reduction potential and an intermetallic compound. The use of oxidation-resistant solder 302, which can suppress the formation of oxides in the solder, improves the heat conduction characteristics of the solder joint 304 and significantly improves the solder strength, especially thermal fatigue strength. it can. Further, in the oxidation-resistant solder 302, the generation of oxides in the intermetallic compound can be suppressed, so that the wettability can be improved and the generation of void defects in the solder joint 304 can be suppressed.

[0211] Another method of uniformly installing oxidation-resistant solder 302 on the soldering surface of first element member 300 from which oxide film 303 has been removed will be described with reference to FIG.

[0212] In this installation method, the powder of the oxidation-resistant solder 302 is made to collide with the air or an inert gas at high speed in the air at room temperature or in an inert gas atmosphere to the soldering surface of the first element member 300, The oxidation-resistant solder is laminated on the soldering surface of the first element member 300. The powder of the oxidation-resistant solder 302 may be laminated on the soldering surface of the second element member 301 in the same manner.

[0213] Here, the collision velocity of the powder of the oxidation-resistant solder 302 that collides with the soldering surface of the first element member 300 or the second element member 301 together with air or an inert gas is 100 m / sec or more. Preferably, there is. If the collision speed is higher than this, as shown in Fig. 28, the powder of the oxidation-resistant solder 302 is sufficiently plastically deformed and laminated on the soldered surfaces of the first element member 300 and the second element member 301. can do.

[0214] The oxidation-resistant solder 302 may be installed in the air and using air as a medium for transporting the oxidation-resistant solder 302. However, the oxidation-resistant solder 302 may be attached to the first element member. In order to prevent oxidation due to heat generated when it collides with the soldering surface of the component 300 or the second element member 301, it is performed in an inert gas atmosphere and using an inert gas as a carrier medium for the oxidation-resistant solder 302. Preferably. Note that lamination of the oxidation-resistant solder 302 on the first element member 300 and the second element member 301 on the soldering surface can be performed by shot blast or air blast.

[0215] In this soldering method, since the oxidation-resistant solder 302 having a lower electrochemical reduction potential and capable of suppressing the formation of oxides in the intermetallic compound is used, the solder joint 304 In this case, the heat conduction characteristics can be improved, and the solder strength, particularly, the thermal fatigue strength can be significantly improved. In addition, the oxidation-resistant solder 302 Since generation of oxides in the compound can be suppressed, wettability can be improved, and generation of void defects in the solder joint 304 can be suppressed.

[0216] In this soldering method, the oxidation-resistant solder 302 is laminated on the soldering surfaces of the first element member 300 and the second element member 301 from which the oxide film 303 has been removed. In this case, it is not necessary to use the flux used to remove the oxide film 303 and apply the oxidation-resistant solder 302. Therefore, since the thickener contained in the flux does not remain as a residue in the solder joint 304, heat transfer characteristics, solder strength, thermal fatigue strength, and the like can be improved.

Next, a specific example of the fourth embodiment will be described.

[0218] (Example 10)

Oxidation-resistant solder powder was produced by dissolving Sn-0.7% by weight〇11_0.1% by weight 01 and atomizing using Ar gas at a pressure of 20 kgfZcm ² . The obtained oxidation-resistant solder powder was sieved through a sieve to obtain an oxidation-resistant solder powder having an average particle size in the range of 5 μm to 35 μm.

[0219] Next, the collected oxidation-resistant solder powder was mixed with N gas at a collision speed of about 150.

Two

At a rate of m / s, the copper plate struck the soldering surface of the Ni-plated Cu plate and laminated to form a solder layer with a thickness of about 100 μm.

[0220] Subsequently, a SiN substrate was placed on the solder layer laminated on the soldering surface of the Cu plate, and N

Soldering was performed at 260 ° C for 3 minutes in a 2 gas atmosphere.

[0221] As a result of measuring and evaluating the void defect of the soldered laminated member by an ultrasonic flaw detection method, the occupation ratio of the void defect was 6% by volume. The shear strength of the cross section of the soldered joint of the soldered laminated member was measured and evaluated. The shear strength was 32 MPa. In addition, a thermal fatigue test was performed under the conditions of a load shear stress of 15 MPa and a temperature of 140 ° C to 100 ° C. As a result, no cracks were observed even after 1000 cycles.

(Example 11)

Sn-3. 5 eight _§ wt% Rei_11_0. 1 was dissolved wt%? 01, the pressure by an atomizing method using Ar gas 20 kgf / cm ^2, to produce a oxidation resistant solder powder. The resulting oxidation resistance The solder powder was sieved with a force of 4 mm, and an oxidation resistant solder powder having an average particle size in the range of 5 μm to 35 μm was collected.

[0223] Next, the collected oxidation-resistant solder powder was mixed with N gas at a collision speed of about 150.

Two

At a time of mZ seconds, the copper plate collided with the soldering surface of the Ni-plated Cu plate and laminated to form a solder layer with a thickness of about 100 μm.

[0224] Subsequently, a SiN substrate was placed on the solder layer laminated on the soldering surface of the Cu plate, and N

Soldering was performed at 260 ° C for 3 minutes in a 2 gas atmosphere.

[0225] The void defect was occupied by 7.5% by volume as a result of measuring and evaluating void defects in the soldered laminated member by an ultrasonic flaw detection test method. The shear strength of the section of the soldered joint of the soldered laminated member was measured and evaluated. The shear strength was 46 MPa. In addition, a thermal fatigue test was performed under the conditions of a load shear stress of 15 MPa and a temperature of 140 ° C to 100 ° C. As a result, no cracks were observed even after 1000 cycles.

(Example 12)

Oxidation-resistant solder powder was produced by the atomization method using Sn-0.7 wt% 01-0.2 wt% Mn dissolved and Ar gas at a pressure of 20 kgf / cm ² . The resulting Chikarake sieved oxidation resistance solder Dano powder was collected an average particle diameter of 5 _beta m-35 _beta oxidation resistance solder powder powder in the range of m.

Next, 10% by weight of flux was added to the collected oxidation-resistant solder powder to prepare a paste-like solder. Subsequently, this paste-like solder was screen-printed on the soldering surface of the Cu plate to form a printed film with a thickness of about 100 μm.

[0228] Subsequently, a SiN substrate was placed on the solder layer laminated on the soldering surface of the Cu plate, and N

Soldering was performed at 260 ° C for 3 minutes in a 2 gas atmosphere.

[0229] The void defect was occupied by 7% by volume as a result of measuring and evaluating the void defect of the soldered laminated member by an ultrasonic inspection method. The shear strength of the cross section of the soldered joint of the soldered laminated member was measured and evaluated. The shear strength was 35 MPa. Furthermore, as a result of a thermal fatigue test performed under the conditions of a load shear stress of 15 MPa and a temperature of 140 ° C to 100 ° C, no cracks were observed even after 1000 cycles. won.

(Example 13)

Sn-0. 5 wt% 01-0. 2 was dissolved wt% Ni-0 · 2% by weight Mn, the atomizing pressure using Ar gas 20 kgf / cm ² method, producing the oxidation resistant solder powder did. The obtained oxidation-resistant solder powder was sieved through a sieve to obtain an oxidation-resistant solder powder having an average particle size in a range of 5 μm to 35 μm.

Next, 10% by weight of flux was added to the collected oxidation-resistant solder powder, and a paste-like solder was prepared. Subsequently, this paste-like solder was screen-printed on the soldering surface of the Cu plate to form a printed film with a thickness of about 100 μm.

[0232] Subsequently, a SiN substrate was placed on the solder layer laminated on the soldering surface of the Cu plate, and N

Soldering was performed at 260 ° C for 3 minutes in a 2 gas atmosphere.

[0233] As a result of measuring and evaluating void defects in the soldered laminated member by an ultrasonic flaw detection test method, the occupation ratio of the void defects was 5% by volume. In addition, the shear strength at the cross section of the soldered joint of the soldered laminated member was measured and evaluated. As a result, the shear strength was 40 MPa. In addition, a thermal fatigue test was conducted under the conditions of applied shear stress of 15 MPa and a temperature of 140 ° C to 100 ° C. As a result, no cracks were observed even after 1000 cycles.

[0234] (Comparative Example 6)

Oxidation-resistant solder powder was manufactured by an atomizing method using Ar gas at a pressure of 20 kgf / cm ² by dissolving Sn-0.75 wt% # 11 solder. Sieved powder powder obtained oxidation resistance solder was collected adopted oxidation resistance solder powder ranges average particle size of 5 μ m- 35 β _m.

[0236] Subsequently, a SiN substrate was placed on the solder layer laminated on the soldering surface of the Cu plate, and N

Soldering was performed at 260 ° C for 3 minutes in a 2 gas atmosphere.

[0237] A void defect was measured and evaluated for the soldered laminated member by an ultrasonic testing method. As a result, the occupation ratio of the void defect was 15% by volume, and this occupation ratio was 2.5 times the occupation ratio of the void defect in Example 10. Also, as a result of measuring and evaluating the shear strength at the cross section of the solder joint of the soldered laminated member, the shear strength was 13 MPa, and this shear strength was about 2Z5 times the shear strength in Example 10. Furthermore, as a result of a thermal fatigue test performed under the conditions of a load shear stress of 15 MPa and a temperature of −40 ° C. and 100 ° C., cracks were observed even after 1000 cycles.

[0238] From these results and the results of Example 10, it can be seen that the inclusion of the second auxiliary component can reduce the occupancy of void defects and improve the shear strength in the cross section of the solder joint. Further, by containing the second auxiliary component, it is possible to exhibit excellent characteristics with respect to thermal fatigue.

[0239] (Comparative Example 7)

Oxidation-resistant solder powder was produced by an atomizing method using Sn-3.5 wt% _octasol solder and Ar gas at a pressure of 20 kgf / cm ² . The obtained oxidation-resistant solder powder was sieved to collect an oxidation-resistant solder powder having an average particle size in a range of 5 μm to 35 μm.

[0241] Next, a SiN substrate was placed on the solder layer laminated on the soldering surface of the Cu plate, and N

Soldering was performed at 260 ° C for 3 minutes in a 2 gas atmosphere.

[0242] The void defect was occupied by 17% by volume as a result of measuring and evaluating the void defect of the soldered laminated member by the ultrasonic flaw detection test method. More than twice the rate. Further, as a result of measuring and evaluating the shear strength at the cross section of the solder joint of the soldered laminated member, the shear strength was 18 MPa, and this shear strength was about 2Z5 times the shear strength in Example 11. Furthermore, as a result of a thermal fatigue test performed under the conditions of a load shear stress of 15 MPa and a temperature of −40 ° C. and 100 ° C., cracks were observed even after 1000 cycles.

[0243] From this result and the result of Example 11, the inclusion of the second auxiliary component allows the void defect to be occupied. Power S can be reduced, and the shear strength at the cross section of the solder joint can be improved. Further, by containing the second auxiliary component, it is possible to exhibit excellent characteristics with respect to thermal fatigue.

Here, Table 3 shows the compositions and measurement results of the solders of the above-mentioned Examples and Comparative Examples.

[Table 3]

(Fifth embodiment)

Hereinafter, the solder material of the fifth embodiment will be described. [0246] The solder material of the fifth embodiment is the same as the solder described in the first embodiment, except that the first solder is the lead-free solder described in the third embodiment.

[0247] In other words, the first solder is a Sn-based alloy containing 0.02-2.0% by weight of Co, not containing Sn or Pb, or 0.02-2.0% by weight of Co and 0% by weight of Cu. 02—7.5% by weight, with the balance being a Sn-based alloy consisting of Sn and unavoidable impurities. The second solder is the same as that described in the first embodiment, and has the property of expanding when solidified, such as Bi, Sb, Ga, or Ge, or a Bi alloy, an Sb alloy, or a Ga alloy. , Ge alloy and the like. Further, the contents of Bi, Sb, Ga, and Ge contained in the Bi alloy, the Sb alloy, the Ga alloy, and the Ge alloy, respectively, are as described in the first embodiment.

[0248] The content of the second solder in the first solder is the same as that in the first embodiment, and the amount of strain in the solder phase calculated from the difference in the thermal expansion coefficients of the members to be joined. Therefore, it is appropriately set in the range of 5-50% by volume.

[0249] The reaction prevention film formed on the surface of the second solder is formed of a metal, ceramic, or resin having a melting point higher than the melting point of the material forming the first solder. The metal, ceramics, or resin forming the reaction prevention film is the same as the reaction prevention film described in the first embodiment. Further, the thickness of the reaction prevention film is also the same as that of the reaction prevention film described in the first embodiment.

[0250] When the soldering conditions such as the soldering temperature and the holding time are controlled to suppress the diffusion or alloying reaction, the mechanical properties and physical properties of the first solder and the second solder can be maintained. Need not be provided with a reaction prevention film. Also, the oxidation-resistant solder of the fourth embodiment may be used as the first solder. Further, the second solder powder 102 of the second embodiment may be used as the second solder.

[0251] In addition to the configuration in which the second solder is uniformly dispersed in the first solder, for example, as shown in FIGS. 5A, 5B, and 5C, the second solder is unevenly distributed in the first solder beforehand. It can be configured with Further, the first solder and the second solder may be configured separately, and as shown in FIGS. 1A, 3A, and 4A, each may be stacked and arranged, and then soldered.

[0252] By performing solder joining using the solder material of the fifth embodiment, both effects obtained in the first embodiment and the third embodiment can be obtained. In other words, join Generation of internal stress in the solder member due to a difference in thermal expansion coefficient between the two members is suppressed, and as a result, deformation of the joining member can be reduced. In addition, since the second solder is covered with the reaction preventing film, there is no diffusion or alloying reaction between the first solder and the second solder, so that the first solder and the second solder are alloyed to form the first solder. It does not lose its inherent properties such as the mechanical properties of the solder and the solidification and expansion properties of the second solder. As a result, it is possible to maintain the unique characteristics of each of the first solder and the second solder, and to exert the maximum performance of the solder member.

[0253] Furthermore, by using a solder containing 0.02-2.0% by weight of Co as the first solder, the surface tension of the Sn or Sn-based alloy can be reduced and the wettability can be improved. . In addition, by suppressing the reaction between the joining member and Sn or Sn-based alloy and suppressing the growth of intermetallic compounds at the joining interface, it is possible to suppress aggregation of molten solder and improve wettability. . As a result, generation of void defects is suppressed, and a solder joint having excellent thermal conductivity, mechanical strength, and the like can be obtained.

Next, a specific example of the fifth embodiment will be described.

[0255] (Example 14)

Sn—57% by weight with an average particle size of 25-45 μm: (1) An Al O film having a thickness of about 50 nm was formed on the surface of the powder by a sol-gel method, and a second solder was manufactured. Then, this second

twenty three

If the average particle size is 25-45 / im Sn-0.7% by weight〇11-0.2% by weight〇0 The first solder consisting of powder and the second solder content will be 20% by volume To make a composite solder material. In order to remove the oxide film on the surface of the bonding material and to facilitate screen printing and coating, an appropriate amount of flux and a resin binder were added to the composite solder to prepare a creamy composite solder.

Subsequently, a composite solder was screen-printed at a thickness of about 150 zm on the surface of the first oxygen-free Cu-based member having a thickness of 3 mm, a width of 100 mm, and a length of 200 mm. Then, a second member of a 0.3 mm thick, 80 mm wide, 180 mm long SiN substrate lined with 100 zm thick pure Cu on both sides is placed on the screen printed composite solder. Thus, a laminated joining member was formed. Subsequently, the laminated joining member was placed in an N gas atmosphere at a temperature of 240 ° C. for 3 minutes.

Two

During heating, soldering was performed. [0257] In the same manner as in the example of the first embodiment, the shear strength of the solder phase at the soldered portion of the first and second members joined by soldering was measured and evaluated. Met. Further, as a result of measuring the amount of deformation of the Cu base in the same manner as in the example of the first embodiment, the amount of deformation of the Cu base of the first member was 85 × m. Further, the composite solder material composed of the first solder and the second solder was melted by the same method as in the example of the third embodiment, and the surface tension ( _Ί ) was measured. As a result, the surface tension _(Ί

L

) Was 0.35 N / m.

L

[0258] The measurement results of the shear strength and the deformation amount of the Cu base in Example 14 above were almost the same level as the measurement results of the shear strength and the deformation amount of the Cu base in Examples 13 to 13. Was. This proved that the mechanical properties of the first solder could be maintained. Furthermore, it was found that the solidification and expansion effect of the second solder can suppress the deformation of the Cu base of the first member.

[0259] The measurement results of the surface tension (γ) of Example 14 are shown in Tables in Examples 7-9.

L

The measurement result at almost the same level as the measurement result of the surface tension (γ) was obtained. This power, wet

L

It was found that it had excellent properties.

As described above, the embodiments of the present invention have been described based on examples. However, the present invention is not limited to these embodiments, but includes the technical ideas described in the claims. It can be changed in the range.

Industrial applicability

[0261] The solder member, the solder material, the soldering method, the method for producing the solder material, and the solder joint member according to the present invention can be used for joining electronic products and the like. Therefore, it has industrial applicability.

Claims

The scope of the claims

[1] A solder member for joining a first member and a second member having a material characteristic different from the first member,

The first solder phase,

A second solder phase dispersed in the first solder phase so as to have a plurality of regions, having a lower melting point than the first solder phase, and having solidification and expansion properties;

A boundary layer present at a boundary between the first solder phase and the second solder phase and having a higher melting point than the first solder phase;

A solder member comprising:

[2] The solder member according to claim 1,

Between the first solder phase and the second solder phase without any diffusion or alloying reaction between the first solder phase and the second solder phase present in the first solder phase. A solder member characterized by maintaining its unique physical and mechanical properties.

[3] The solder member according to claim 1,

The low melting point metal is one material selected from the group consisting of Sn, Bi, In, Zn, Sn alloy, Bi alloy, In alloy, and Zn alloy, and the metal having the property of solidification expansion is Bi. A solder member characterized in that it is a material selected from the group consisting of Sb, Ga, Ge, Bi alloy, Sb alloy, Ga alloy, and Ge alloy.

[4] The solder member according to claim 1,

The solder member, wherein the boundary layer is formed of one kind of material selected from the group consisting of a metal, a ceramic, and a resin.

[5] The solder member according to claim 1,

The solder member, wherein the second solder phase exists uniformly dispersed in the first solder phase or is unevenly distributed at a predetermined portion of the first solder phase.

[6] A solder material for joining the first member and the second member having a different characteristic material strength,

The first solder material, A boundary coating having a melting point higher than that of the first solder material is formed on the surface, and a second solder material having a melting point lower than that of the first solder material and having a property of solidification expansion. And the solder material.

[7] The solder material according to claim 6, wherein

The first solder material is composed of one material selected from the group consisting of Sn, Bi, In, Zn, Sn alloy, Bi alloy, In alloy, and Zn alloy, and the second solder material is Bi, Sb A solder material comprising one material selected from the group consisting of Ga, Ge, Bi alloy, Sb alloy, Ga alloy, and Ge alloy.

[8] The solder material according to claim 6, wherein

The solder material, wherein the boundary film is formed of one material selected from the group consisting of a metal, a ceramic, and a resin.

[9] A soldering method for joining a first member and a second member having a material characteristic different from the first member,

A boundary coating is formed on the surface, and a second solder material having a second melting point lower than the first melting point of the material forming the boundary coating and having the property of solidification expansion is used as the first component. A second solder material disposing step for disposing on the surface,

A first solder material disposing step of disposing a first solder material having a third melting point lower than the first melting point and higher than the second melting point on the second solder material; (1) a second member installation step of installing the second member on the solder material; and a second member installation step, the laminated member is placed in the air or an inert gas atmosphere, A heating step of heating at a temperature higher than the melting point and lower than the first melting point;

A soldering method comprising:

[10] Sn-based alloy containing 50% by weight or more of Bi, Sn-based alloy containing 6% by weight or more of Sb, and reaction suppression on the surface of second solder phase powder composed of at least one of Bi and Sb A boundary film forming step of forming a film;

A mixture for producing a mixture in which the powder of the second solder phase and the powder of the first solder phase having an average diameter of 1 to 100 am and made of Sn or a Sn-based alloy are uniformly mixed at a predetermined ratio. Manufacturing process;

A paste-like mixture producing step of producing a paste-like mixture by mixing and stirring a flux and a binder at a predetermined ratio with the mixture;

A method for producing a solder material, comprising:

[11] Sn-based alloy containing 50% by weight or more of Bi, Sn-based alloy containing 6% by weight or more of Sb, and reaction suppression on the surface of second solder phase powder composed of at least one of Bi and Sb A boundary film forming step of forming a film,

A mixture producing step of producing a mixture in which the powder of the second solder phase and the first solder phase composed of Sn or a Sn-based alloy having an average diameter of 1 to 100 am and a predetermined ratio are uniformly mixed,

A complexing step of complexing the mixture by pressurizing and heating;

A forming step of forming the compounded mixture into a film or a wire.

[12] A solder material containing a Sn-based alloy containing 0.0 to 2.0% by weight of Co and containing no Sn or Pb.

[13] A solder material comprising 0.02 to 2.0% by weight of Co and 0.02 to 7.5% by weight of Cu, with the balance being Sn and unavoidable impurities.

[14] A first auxiliary component composed of at least one metal selected from Cu, Ag, Au, Co and Ni is contained in an amount of 0.02 to 12% by weight, and at least one type selected from Mn, Pd and Pt is contained. A solder material comprising 0.02-1.2% by weight of a second secondary component made of a metal, with the balance being Sn and unavoidable impurities.

[15] Sn-base alloy containing 0.0-2.0% by weight of Co, not containing Sn or Pb, or 0.02-2.0% by weight of Co and 0.02-7.5% by weight of Cu % Solder, with the balance being Sn and unavoidable impurities,

With Sn or Pb-free solder, and a second solder made of Sn-based alloy

A solder material comprising:

[16] Sn-based alloy containing 0.0-2.0% by weight of Co, not containing Sn or Pb, or 0.02-2.0% by weight of Co, 0.02-7.5% of Cu %, The balance being Sn and inevitable impurities A solder joint member comprising a first member and a second member joined by using a solder material made of an object.

[17] A solder member for joining the first member and the second member,

A first solder phase comprising a Sn-based alloy, containing Sn or Pb, containing 0.0-2.0% by weight of Co;

Bi, Sb, Ga, Ge, Bi alloy, Sb alloy, dispersed to have a plurality of regions in the first solder phase, having a lower melting point than the first solder phase, and having the property of solidification expansion. A second solder phase made of one material selected from the group consisting of Ga alloy and Ge alloy

A solder member comprising:

[18] Sn-based alloy containing 0.0-2.0% by weight of Co, Sn or Pb, or 0.02-2.0% by weight of Co, 0.02-7.5% by weight of Cu % Solder, with the balance being Sn and unavoidable impurities,

From a material selected from the group consisting of Bi, Sb, Ga, Ge, Bi alloy, Sb alloy, Ga alloy, Ge alloy, which has a lower melting point than the first solder and has the property of solidification expansion. Becomes the second solder

A solder material comprising: