JP2014038909A - Component mounting board and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new high-density component mounting board and a manufacturing method of it to solve a restriction in circuit design and variation of a component joint shape due to a change in component locations during solder melting.SOLUTION: A manufacturing method of a component mounting board includes the following processes: applying a conductive paste on a plurality of electrodes on a circuit board; arranging a part of at least two electronic components on one electrode with the conductive paste applied; and forming a joint part by jointing the part of at least two electronic components to the one electrode through heat treatment of the conductive paste. The conductive paste includes: solder particles, high-melting point metal particles whose melting point is higher than that of the solder particles, and flux; or composite metal particles with a surface of the high-melting point metal particles plated with a solder, and flux.

Description

  The present invention relates to a component mounting board and a manufacturing method thereof.

  With the recent improvement in performance of electronic devices, the development of high-density mounting technology has been remarkable, and more electronic components have been mounted per unit area. Therefore, the board design is made so that the gap between board electrodes or the gap between parts is made narrower. In addition, the size of electronic components to be mounted has been remarkably reduced. For example, with regard to passive components, conventional 1005 (1.0 mm × 0.50 mm) size or 0603 (0.60 mm × 0.30 mm) size components Instead, in recent years, a large number of 0402 (0.40 mm x 0.20 mm) size components have been mounted, and further miniaturization to 0201 (0.20 mm x 0.10 mm) size is expected in the future. The

  Aside from this, a general component mounting board has one electronic component (for one board electrode 3 (a) after solder paste printing in FIG. 1 and FIG. 2 and (b) after component mounting. Since the terminal 6 is bonded with a bonding material such as the solder paste 5, it is necessary to provide the substrate electrode 3 according to the number of terminals of the component to be mounted. At this time, since it is necessary to provide a certain gap between the substrate electrodes, there is a practical design limit for high-density mounting.

  On the other hand, Patent Document 1 proposes a component mounting method in which two chip components are joined in series via one solder paste application part, and before and after reflow due to surface tension at the time of melting of solder particles. One technique for changing the part position and narrowing the gap between parts is disclosed.

JP 2000-269628 A

  However, the component mounting method of Patent Document 1 is a method of narrowing the distance between chip components before and after reflow using the surface tension at the time of melting the solder, and the position of the component may change before and after reflow. Only applicable. Also, from the viewpoint of stabilizing the bonding state, it is necessary to design the substrate and printing mask so that the electronic component is bonded at a specific position and at a specific angle by the surface tension during solder melting. It can be said that the design of the circuit board that can be limited.

  Further, as shown in FIG. 3 (a) after solder paste printing, (b) after component mounting, and (c) after heat treatment, three or more electronic components 6 are mounted in series as in Patent Document 1. In this case, the melted solder paste component 5 wets the component electrode 3 due to surface tension and tries to narrow the gap between components, but the force to narrow the gap between components works at two different locations. As shown, the mounting position of the electronic component 6 or the shape of the connecting portion varies in the longitudinal direction of the component. In particular, the above phenomenon becomes significant when the sizes or types of components mounted in series are different. For this reason, the connection stability of each component joint also varies. Furthermore, the random change in the position of the component before and after the heat treatment as described above is that the coordinates of the joint portion randomly change with respect to the XY coordinates of the board surface when the appearance inspection of the component joint portion is performed after the heat treatment. Therefore, optical inspection or the like becomes difficult.

  Moreover, regarding the parallel mounting method of electronic components as shown in FIG. 4 (details will be described later), when a general Pb-free solder paste (Sn3.0Ag0.5Cu or the like) is used, the components flow. There is no known method for effective suppression.

  The problem to be solved by the present invention is to solve the limitation in circuit design or the variation of the component joint shape due to the change of the component position at the time of melting the solder as described above, and has been considered difficult by the conventional mounting method. In addition, a new method for manufacturing a high-density component mounting board is proposed.

The present invention solves the above problems by using the following method.
That is, the present invention is as follows.

[1] The following steps:
Applying a conductive paste on a plurality of electrodes on a circuit board;
Disposing a part of at least two electronic components on one electrode coated with the conductive paste; and heat treating the conductive paste to convert a part of the at least two electronic components to the electrode. Joining to one electrode to form a joint;
A component mounting board manufacturing method including:
The conductive paste contains solder particles, refractory metal particles having a higher melting point than the solder particles, and flux, or
The method comprising: composite metal particles obtained by solder plating the surface of the refractory metal particles, and a flux.

[2] The following steps:
Applying a conductive paste on a metal surface in a plurality of predetermined regions on the substrate;
Disposing a part of at least two electronic components in one predetermined region to which the conductive paste is applied;
Bonding a part of the at least two electronic components to a metal surface in the one predetermined region by heat-treating the conductive paste to form a joint; and outside the predetermined region of the metal surface; Selectively etching to form a wiring pattern made of metal remaining in the predetermined region;
A component mounting board manufacturing method including:
The conductive paste contains solder particles, refractory metal particles having a higher melting point than the solder particles, and flux, or
The method comprising: composite metal particles obtained by solder plating the surface of the refractory metal particles, and a flux.

  [3] The component mounting board manufacturing method according to [1] or [2], wherein the electronic component is a two-terminal element.

  [4] The component mounting board manufacturing method according to [3], wherein both ends of the two-terminal element are joined to an electrode on a circuit board or a metal surface by the different joint portions.

  [5] Any one of [1] to [4], wherein the refractory metal particles are refractory metal particles having a melting point of 280 ° C. or higher, including at least one metal selected from Cu, Ag, Ni, and Au. 2. The component mounting board manufacturing method according to item 1.

  [6] The component mounting board manufacturing method according to [5], wherein the refractory metal particles further include In and / or Ge.

  [7] The solder particles or the solder plating is at least selected from the group consisting of Sn composition, Sn, and Ag, Bi, Cu, Ge, Ga, In, Sb, Ni, Zn, Pb, and Au. The component mounting board manufacturing method according to any one of [1] to [6], which is an Sn alloy composition including one kind of metal.

  [8] The component mounting board manufacture according to any one of [1] to [7], wherein the conductive paste includes 17 parts by mass or more of the refractory metal particles with respect to 100 parts by mass of the solder particles. Method.

  [9] The component mounting board manufacturing method according to any one of [1] to [8], wherein the flux includes at least one of an organic acid, an amine compound, and a halogen compound.

  [10] The component mounting board manufacturing method according to [9], wherein the flux further includes a thermosetting resin.

  [11] The component mounting board manufacturing method according to [10], wherein the flux further includes a curing agent.

[12] The following steps:
Applying a conductive paste on a plurality of electrodes on a circuit board;
Disposing a part of at least two electronic components on one electrode coated with the conductive paste; and heat treating the conductive paste to convert a part of the at least two electronic components to the electrode. Joining to one electrode to form a joint;
Including
The conductive paste is solder particles, high melting point metal particles having a melting point higher than the solder particles, and flux, or
The component mounting board manufactured by the component mounting board manufacturing method including the composite metal particles obtained by solder plating the surface of the refractory metal particles and the flux, and the joint portion has a solder matrix containing Sn, The solder matrix includes refractory metal particles containing at least one metal selected from the group consisting of Cu, Ag, Ni, and Au, and the melting point of the refractory metal particles is higher than the melting point of the solder matrix. The component having a high and high melting point metal particle has an intermetallic compound phase containing Sn and at least one metal selected from the group consisting of Cu, Ag, Ni, and Au. Mounting board.

[13] The following steps:
Applying a conductive paste on a metal surface in a plurality of predetermined regions on the substrate;
Disposing a part of at least two electronic components in one predetermined region to which the conductive paste is applied;
Bonding a part of the at least two electronic components to a metal surface in the one predetermined region by heat-treating the conductive paste to form a joint; and outside the predetermined region of the metal surface; Selectively etching to form a wiring pattern made of metal remaining in the predetermined region;
Including
The conductive paste contains solder particles, refractory metal particles having a higher melting point than the solder particles, and flux, or
A component mounting board manufactured by a component mounting board manufacturing method including a composite metal particle having a solder plating on the surface of the refractory metal particles and a flux, wherein the joint has a solder matrix containing Sn, and the solder The matrix includes refractory metal particles containing at least one metal selected from the group consisting of Cu, Ag, Ni, and Au, the melting point of the refractory metal particles being higher than the melting point of the solder matrix, In addition, the component mounting board, wherein at least one metal selected from the group consisting of Cu, Ag, Ni, and Au and an intermetallic compound phase containing Sn are present on the surface of the refractory metal particles .

  [14] The component mounting board according to [12] or [13], wherein the electronic component is a two-terminal element.

  [15] The component mounting board according to [14], wherein both ends of the two-terminal element are joined to an electrode on a circuit board or a metal surface by the different joints.

  [16] The component mounting board according to [15], wherein two or more of the two-terminal elements are joined in parallel.

  [17] Any one of [12] to [16], wherein the refractory metal particles are refractory metal particles having a melting point of 280 ° C. or higher, including at least one metal selected from Cu, Ag, Ni, and Au. The component mounting board according to claim 1.

  [18] The component mounting board according to [17], wherein the refractory metal particles further include In and / or Ge.

  [19] The solder matrix contains Sn composition or at least one metal selected from the group consisting of Sn and Ag, Bi, Cu, Ge, Ga, In, Sb, Ni, Zn, Pb, and Au. The component mounting board according to any one of [12] to [18], which includes an Sn alloy composition.

  [20] The intermetallic compound phase is Cu—Sn, Ni—Sn, Cu—Sn—Ni, Ag—Sn, Au—Sn, Cu—Sn—In, Cu—Sn—Ge, or Cu—Sn—In—. The component mounting board according to any one of [12] to [19], including any one of Ge.

  [21] A module obtained by molding the component mounting board according to any one of [12] to [20] with a thermosetting resin.

  [22] A component-embedded substrate obtained by laminating the component mounting substrate according to any one of [12] to [20].

  According to the present invention, it is possible to provide a high-density component mounting board and a method for manufacturing the same, in which there are few restrictions on circuit design due to changes in the component position at the time of melting the solder or variations in the component bonding shape.

It is a top view of the conventional component mounting board. It is a top view of the conventional component mounting board. It is a top view of the component mounting example using the same junction part. It is a flowchart which shows an example of the manufacturing method of this Embodiment. It is a flowchart which shows an example of the manufacturing method of this Embodiment. It is a flowchart which shows an example of the manufacturing method of this Embodiment. It is a flowchart which shows an example of the manufacturing method of this Embodiment. It is a flowchart which shows an example of the manufacturing method of this Embodiment. It is the schematic which shows the board | substrate of Examples 1-26 and Comparative Examples 1-3, a printing pattern, and component arrangement conditions. It is the schematic which shows the notation method of the gap between components. It is the schematic which shows the board | substrate of Examples 27-34 and Comparative Examples 4-7, a printing pattern, and component arrangement conditions. It is an imaging figure which shows the components mounting board | substrate appearance before and behind heat processing of the comparative example 7. It is an imaging figure which shows the component mounting board | substrate appearance before and behind heat processing of Example 34. It is the schematic which shows the board | substrate of Examples 35-38 and Comparative Examples 8-9, a printing pattern, and component arrangement conditions. It is an imaging figure which shows the components mounting appearance after heat processing of Examples 36 and 37 and Comparative Example 9. It is a schematic sectional drawing of the junction part for evaluating component joining shape dispersion | variation.

  Hereinafter, modes for carrying out the present invention (hereinafter abbreviated as embodiments) will be described in detail. In addition, this invention is not limited to the following embodiment, It can deform | transform and implement within the range of the summary.

In the present embodiment, a process of applying a conductive paste on a plurality of electrodes on a circuit board,
Disposing a part of at least two electronic components on one electrode to which the conductive paste is applied, and heat treating the conductive paste to form a part of the at least two electronic components; A component mounting board manufacturing method including a step of bonding to the one electrode to form a bonding portion, wherein the conductive paste includes solder particles, refractory metal particles having a melting point higher than the solder particles, and Provided is a composite metal particle including a flux or solder-plated on the surface of the refractory metal particle, and a component mounting board manufacturing method including the flux.

  The junction in the present embodiment means a specific junction for joining a part of at least two electronic components to one substrate electrode or a metal surface in a predetermined region. Moreover, the joining of an electronic component shall join the terminal which this electronic component has.

The conductive circuit or electrode on the circuit board may be formed after the heat treatment, that is, a step of applying a conductive paste on a metal surface in a plurality of predetermined regions on the substrate, and the conductive paste is applied. Disposing at least a part of at least two electronic components in one predetermined region, heat treating the conductive paste to convert a part of the at least two electronic components into a metal in the one predetermined region Manufacturing a component mounting board including a step of bonding to a surface to form a bonding portion, and a step of selectively etching outside a predetermined region of the metal surface to form a wiring pattern made of metal remaining in the predetermined region The conductive paste includes solder particles, refractory metal particles having a melting point higher than that of the solder particles, and flux, or the surface of the refractory metal particles is solder-plated. Composite metal particles, and also the component mounting board manufacturing method comprising a flux relates. When performing the etching, it is preferable to selectively etch using a resist on the back surface of a metal surface on which no parts are mounted and there are few irregularities.
A detailed form will be described below.

<Conductive paste>
The conductive paste used in the present embodiment includes solder particles, refractory metal particles having a melting point higher than that of the solder particles, and a composite metal particle containing a flux or solder-plated on the surface of the refractory metal particles, And a conductive paste containing flux.

  The heat treatment of the conductive paste is preferably performed at a temperature higher than the melting point of the solder particles and at a temperature lower than that of the refractory metal particles. The heat treatment melts the solder particles or the solder plating, and the molten solder component causes a metal diffusion phenomenon with the refractory metal particles, and the surface of the refractory metal particles is higher than the melting point of the solder component. An intermetallic phase is formed. Therefore, when the conductive paste is heat-treated under the above-described conditions, it is possible to intentionally suppress the melt flow of the electronic component during solder melting before and after the heat treatment. Therefore, when two or more electronic components are bonded onto one electrode via one bonding portion using the conductive paste after the conductive paste is applied on the electrode of the circuit board, the molten solder It can suppress that a component wets unevenly to the terminal of two or more different electronic components, and can suppress that the components which adjoined flow (parts attract each other).

  On the other hand, after applying a general solder (for example, Sn-3.5Ag-0.5Cu composition) paste on the electrode of the circuit board, two or more electronic components are passed through one joint portion by the solder paste. When joining on one electrode, the component position flows due to the surface tension of the molten solder particle component during heating, and the molten solder particle component is unevenly distributed between the terminals of two or more different electronic components. Get wet.

  From these facts, by using the conductive paste described in this specification as a bonding material and forming a component mounting structure that is not generally used, high-density mounting that cannot be realized with the general solder paste is achieved. It can be realized. Specific examples of the mounting structure will be described later with reference to FIGS.

[Solder particles]
Solder particles that can be used in the present embodiment, if the melted solder particle component forms an intermetallic compound with the refractory metal particles to be described later, because the component flow at the time of melting the solder can be suppressed, It is not limited to a specific metal composition, Sn composition, or at least one selected from the group consisting of Sn and Ag, Bi, Cu, Ge, Ga, In, Sb, Ni, Zn, Pb and Au It is possible to have a Sn alloy composition containing any of these metals. Further, from the viewpoint of reducing thermal damage to the substrate, the solder particles used in the present embodiment preferably have a melting point of less than 280 ° C.

  Specifically, Sn-Bi system, Sn-In system, Sn-Cu system, Sn-Zn system, Sn-Ag system, Sn-Au system, Sn-Pb system, Sn-Sb system, Sn-Bi-Ag Type, Sn-Ag-Cu type, Sn-Bi-Cu type, Sn-Zn-Bi type, Sn-Bi-In type, Sn-Ag-In type, Sn-Ag-In-Bi type, Sn-Cu- Examples thereof include Ni-based, Sn-Cu-Ni-Ge-based, and Sn-Ag-Cu-Ni-Ge-based solder particles. Examples of the lead-free solder having a recommended reflow peak temperature of the solder paste of 230 ° C. or higher include, for example, Sn—Ag—Cu (for example, Sn-3.0Ag-0.5Cu), Sn—Ag (for example, Sn-3. 5Ag), Sn, etc. are preferred. Moreover, as the lead-free solder whose reflow peak temperature is 200 ° C. or lower, Sn alloy particles containing Sn and containing either Bi, In, or Zn and having a melting point of 200 ° C. or lower are preferable. Among these, Sn-58Bi or Sn-57Bi-1Ag is particularly preferable. Moreover, since the tensile strength or elongation rate of the solder itself can be improved by slightly adding C to the Sn alloy particles at 1.0 wt% or less, the connection reliability is improved.

  Moreover, the solder particles to be used are not limited to one type. For example, by adding Sn particles as the second kind of solder particles to Sn-58Bi particles, it becomes possible to melt Sn-58Bi particles at a low temperature of about 160 ° C. and to diffuse into the molten SnBi component and Sn particles. By doing so, it is possible to reduce the Bi composition of the solder part after the heat treatment. In general, Bi exhibits mechanically brittle characteristics, and therefore the Bi composition after heat treatment can be reduced by adding the Sn particles and Sn alloy particles, leading to improvement in brittleness. As described above, when a plurality of solder particles are added, it is preferable to perform heat treatment at a peak temperature higher by about 10 to 30 ° C. than the melting point of the solder particles having a larger amount (mass).

  Moreover, it is preferable that the average particle diameter of the solder particle to be used is 0.30-50 micrometers, and can be defined according to the use application of a solder paste. For example, in the screen printing application, it is preferable to make the particle size distribution broader with emphasis on the plate slipping property, and the average particle size is preferably 2.0 to 40 μm. The solder paste of the present embodiment can be used for dispensing applications and via filling applications, and a particle size distribution of 1.5 to 35 μm is preferable with emphasis on discharge fluidity and hole filling properties.

[High melting point metal particles]
The refractory metal particles contained in the conductive paste of the present embodiment are preferably refractory metal particles having a melting point of 280 ° C. or higher and containing any of Cu, Ag, Ni, and Au. From the viewpoint of metal diffusibility with the metal particles, the high melting point metal particles are preferably Cu particles, Cu alloy particles, Ag particles, Ag alloy particles, Ni particles, or Ni alloy particles. Further, the refractory metal particles to be used are not limited to one kind, and plural kinds of refractory metal particles may be used as long as they form an intermetallic compound phase with the melting component of the solder particles. The effect is obtained.

As the Cu alloy particles, various properties can be imparted by adding any of In, Ni, Sn, Bi, Ag, and Ge metals to Cu.
For example, since In has the effect of refining the crystal grains of the Cu-Sn intermetallic compound phase formed at the interface between the molten solder and the Cu alloy particles, the Cu alloy particles may contain In. preferable. The content of In in the Cu alloy particles is preferably 0.10 wt% or more, more preferably 1 wt% or more, and further preferably 3 wt% or more, from the viewpoint of forming a stable alloy phase at the joint. . Moreover, since the heat resistance of the joint after heat treatment can be increased by setting the amount of In in the Cu alloy particles to a certain amount or less, the In content is preferably 30 wt% or less, more preferably 15 wt%. % Or less, particularly preferably 10 wt% or less.

  The addition of Sn to the Cu alloy particles improves the wettability with the melted solder. Therefore, the Cu alloy particles preferably contain 2 wt% or more of Sn, and more preferably contain Sn in the Cu alloy particles. The amount is 5 wt% or more, more preferably 10 wt% or more. Further, from the viewpoint of forming an intermetallic compound satisfactorily with the solder, the content of Sn in the Cu alloy particles is preferably 50 wt% or less.

  Further, even when Bi is added to the Cu alloy particles, the wettability with the molten solder is improved. Therefore, the Cu alloy particles preferably contain 0.1 wt% or more of Bi, and more preferably in the Cu alloy particles. The Bi content is 2 wt% or more. Further, since the brittleness of the Cu alloy particles can be improved by keeping the Bi content below a certain level, the Bi content in the Cu alloy particles is preferably 20 wt% or less, more preferably 10 wt% or less. It is.

  Further, Ag forms a heat-resistant joint because it easily forms an intermetallic compound having a high melting point with the Sn component of the molten solder. Therefore, the Cu alloy particles preferably contain 0.1 wt% or more of Ag, and more preferably, the content of Ag in the Cu alloy particles is 2 wt% or more. In view of cost, the content of Ag in the Cu alloy particles is preferably 50 wt% or less, more preferably 20 wt% or less, and even more preferably 10 wt% or less.

  Since Ge is preferentially oxidized when the solder is melted and has an effect of suppressing oxidation of other solder components such as Sn, the Cu alloy particles preferably contain 0.10 wt% or more of Ge. Further, from the viewpoint of preventing the oxide from inhibiting the solder flow and adversely affecting the bondability, the Ge content in the Cu alloy particles is preferably 5.0 wt% or less.

  The Ag alloy particles and the Ni alloy particles preferably contain 5 wt% or more of Sn, and more preferably contain 10 wt% or more of Sn from the viewpoint of improving wettability with molten solder. Moreover, it is preferable that content of Sn is 50 wt% or less from a viewpoint of producing | generating an intermetallic compound favorably between solder. Furthermore, from the viewpoint of improving the bondability at a low temperature, alloy particles with In or Bi are preferable.

  In this embodiment, by adding refractory metal particles to the conductive paste, an intermetallic compound phase having a high melting point is formed at the interface between the molten solder and the refractory metal particles. This makes it possible to control the circuit board that has been virtually impossible to design by the flow of the components during the melting of the solder. Become. On the other hand, if the ratio of the refractory metal particles to the solder particles is too large, the joint ratio of the metal bonds due to the solder components at the joint portion is reduced, and the junction due to the point contact of the refractory metal particles is mainly used. To rise. Therefore, it is possible to determine the ratio between the solder particles and the refractory metal particles according to the material characteristics to be emphasized. For example, from the viewpoint of suppressing component flow during solder particle melting, it is preferably 5 parts by mass or more, more preferably 17 parts by mass or more, and still more preferably 100 parts by mass of solder particles. Is 33 parts by mass or more, and most preferably 53 parts by mass or more. Further, from the viewpoint of connection resistance value, 900 parts by mass or less is preferable with respect to 100 parts by mass of solder particles, more preferably 300 parts by mass or less, 186 parts by mass or less, and most preferably 54 parts by mass or less. is there.

  The average particle size of the refractory metal particles to be used is preferably 50 μm or less from the viewpoint of allowing the diffusion reaction with the molten solder particles to proceed in a short time, and more preferably 30 μm or less in view of screen printing characteristics. On the other hand, when the average particle size is small, the specific surface area is increased, so that the wettability with the molten solder particles is reduced. Therefore, the average particle size of the refractory metal particles is preferably 1.0 μm or more, more preferably. 10 μm or more. Moreover, it can determine according to the use application of a solder paste like the said solder particle. For example, in the screen printing application, it is preferable to make the particle size distribution broader with emphasis on the plate slipping property, and the average particle size is preferably 2.0 to 40 μm. The solder paste of the present embodiment can be used for dispensing applications and via filling applications, and a particle size distribution of 1.5 to 35 μm is preferable with emphasis on discharge fluidity and hole filling properties.

Further, the intermetallic compound phase formed by melting is Cu—Sn (Cu ₃ Sn, Cu ₆ Sn ₅ ), Ni—Sn, Cu—Sn—Ni, Ag—Sn, Au—Sn (Ag ₃ Sn). Cu-Sn-In, Cu-Sn-Ge, Cu-Sn-In-Ge, and the like.

[Solder plating]
For the solder plating used in the present embodiment, a general electroplating or a solder plating process such as electroless plating can be used. As a solder composition, Sn alloy or Sn alloy containing at least one metal selected from the group consisting of Sn and Ag, Bi, Cu, Ge, Ga, In, Sb, Ni, Zn, Pb, and Au. Composition is preferred. Further, from the viewpoint of reducing thermal damage to the substrate, the solder plating used in the present embodiment preferably has a composition with a melting point of less than 280 ° C.

[flux]
The flux contained in the conductive paste used in the present embodiment means an additive having a flux action used in general solder paste, and cleaning of the metal filler surface oxide film during heat treatment, It has an action to suppress reoxidation. From the viewpoint of promoting melting of solder particles and alloying by thermal diffusion, the flux preferably includes an activator such as an organic acid, an amine compound, or a halogen compound. Among them, an organic acid is preferably contained, and examples thereof include rosin, modified rosin, known monocarboxylic acid, dicarboxylic acid, and tricarboxylic acid. For example, glutaric acid, adipic acid, benzoic acid, stearic acid, citric acid, oxalic acid, succinic acid, sebacic acid, malonic acid, pimelic acid, suberic acid, azelaic acid, citraconic acid, α-ketoglutaric acid, diglycolic acid, Thiodiglycolic acid, dithiodiglycolic acid, levulinic acid, 5-ketohexanoic acid, 3-hydroxypropionic acid, 4-aminobutyric acid, 3-mercaptopropionic acid, 3-mercaptoisobutyric acid, 3-methylthiopropionic acid, 3-phenylpropionic acid On acid, 3-phenylisobutyric acid, 4-phenylbutyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, decanoic acid, nonanoic acid, oleic acid, linoleic acid, arachidonic acid, undecylenic acid, 2,2-dimethylbutyric acid , Α-linolenic acid, palmitoleic acid, docosahexaenoic acid, myris And for example, tolenoic acid.

  Also, thixotropic agents (for example, castor oil, hydrogenated castor oil, sorbitol-based thixotropic agents), antifoaming agents, antioxidants, solvents (for example, glycol ether-based solvents), inorganic fillers, etc., for improving paste characteristics Well-known ones used in conventional cream solder can be added.

  Further, the flux may contain a thermosetting resin in order to improve connection reliability such as bonding strength, epoxy resin, phenol resin, cyanate ester resin, melamine resin, polyimide resin, bismaleimide resin, Urea resins, alkyd resins, vinyl ester resins, benzoxazine resins, urethane resins, acrylic resins, and the like can be used, and epoxy resins are preferred from the viewpoint of resin curing characteristics and adhesion at low temperatures. Epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hindered type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin, triphenylmethane type epoxy resin, phenol novolac type epoxy. Resins, cresol novolac type epoxy resins and epoxy resins halogenated from these resins, diglycidyl ethers such as polyethylene glycol, polypropylene glycol, butanediol, hexanediol, and cyclohexanedimethanol can be used. Further, when selecting from polyfunctional epoxy resins having 3 or more epoxy groups in the molecule, for example, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthol novolac type epoxy resin, bis A novolac type epoxy resin, dicyclopentadiene / Phenol epoxy resin, alicyclic amine epoxy resin, aliphatic amine epoxy resin and the like. Among these, from the viewpoint of pasting, a relatively low viscosity bisphenol A type epoxy resin or bisphenol F type epoxy resin is preferable.

Moreover, when the said thermosetting resin is included in a flux, since a thermosetting resin hardens | cures at the time of a heating with the said flux, although a hardening | curing agent is not an essential component, it is preferable to contain a hardening agent separately. In the present specification, the organic acid is treated separately from the curing agent. As the curing agent, known amine compounds, organic acid dihydrazides, phosphorus compounds, phenol resins, acid anhydrides and imidazole curing agents, cationic curing agents such as sulfonium salts, anionic curing agents and the like can be used. Specific examples of amine compounds include alcoholic amines such as monoethanolamine, diethanolamine, and triethanolamine, or butylamine, diethylenetriamine, xylylenediamine, isophoronediamine, norbornenediamine, metaphenylenediamine, guanamine compounds, and amino groups. (E.g. 2,4-diamino-6-methyl-s-triazine, 2,4-diamino-6-vinyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyl) Non-alcoholic amines such as oxyethyl-s-triazine isocyanuric acid adduct), diphenylguanidine, and amine salts such as chloride salts or bromide salts, among which triethanolamine, butylamine, Preferred amine carboxylates.
In addition, as examples of imidazole-based curing agents, product names (2MZ, C11Z, C17Z, 2E4MZ, 2PZ, 2P4MZ, 1B2MZ, 1B2PZ, 1.2DMZ, 2MZ-A, C11Z-A, 2E4MZ-A, manufactured by Shikoku Kasei Co., Ltd. 2MA-OK, 2PZ-OK, 2MZ-OK, 2PHZ, 2P4MHZ, TBZ, 2E4MZ · BIS, SFZ) and the like. Among these, 2MA-OK, 2PZ-OK, and 2MZ-OK, which are isocyanuric acid adducts, are preferable from the viewpoint of improving wet heat resistance after resin curing.

  In addition, the proportion of the curing agent contained in the flux is preferably 0.10 to 60 wt%, more preferably 0.50 to 30 wt%, and even more preferably 1 from the viewpoints of solder particle melting characteristics and storage stability. It is 0.0-14 wt%, Most preferably, it is 5.0-12 wt%.

  For example, when an acid anhydride is used as the curing agent, the ratio of the curing agent contained in the flux is preferably 20 to 60 wt%, and when an imidazole curing agent is used as the curing agent, It is preferable that the ratio of the hardening | curing agent contained in is 1.0-20 wt%, More preferably, it is 2.0-12 wt%. Further, the proportion of the amine compound added to the flux is preferably 20 wt% or less from the viewpoint of storage stability of the flux, and more preferably 0.10 to 14 wt% from the viewpoint of short-time curability and storage stability. More preferably 0.20 to 7.0 wt%, and most preferably 0.50 to 5.0 wt%.

  By adjusting the content of the metal particles contained in the conductive paste so as not to become too high, the viscosity of the paste is optimized, and the printability in screen printing or the like is improved. Conversely, by adjusting so that the content of the metal particles does not become too low, the component bonding strength can be ensured, so the range of 40 to 96% by mass is preferable, and the content of 60 to 94% by mass is more preferable. More preferably, it is 80-93 mass%. The metal particles include the above-described solder particles and refractory metal particles.

<Component mounting board manufacturing process>
In this embodiment, a step of applying a conductive paste on a plurality of electrodes on a circuit board, a step of disposing at least a part of at least two electronic components on one electrode to which the conductive paste is applied And a step of bonding a part of the at least two electronic components to the one electrode by heat-treating the conductive paste to form a bonded portion, the conductive paste comprising solder particles, The present invention relates to a high-melting point metal particle having a melting point higher than that of the solder particle, and a component mounting board manufacturing method including a flux.

  The conductive circuit or electrode on the circuit board may be formed after the heat treatment, that is, a step of applying a conductive paste on a metal surface in a plurality of predetermined regions on the substrate, Disposing at least a part of at least two electronic components in one predetermined area applied; heat-treating the conductive paste to at least part of the at least two electronic parts in the predetermined area; Bonding to a metal surface and forming a bonding portion; and selectively etching outside a predetermined region of the metal surface to form a wiring pattern made of metal remaining in the predetermined region; The conductive paste also relates to a component mounting board manufacturing method including solder particles, refractory metal particles having a higher melting point than the solder particles, and flux.

Hereinafter, detailed preferred embodiments of each step will be described.
[Circuit board]
As the circuit board described in the present specification, a known circuit board such as a glass epoxy board, a ceramic board, a flexible board such as polyimide, and a paper phenol resin board can be used, but a glass epoxy board is preferable from the viewpoint of heat resistance and cost. . As the substrate electrode, a known one can be used as long as it can be metallically bonded to a molten solder component, such as Cu, Au—Pd, Ag, or Au plated Ni. Note that the circuit board shown in this specification includes circuits such as packages and various electronic devices.

[Electronic parts]
The electronic component of the present specification is not particularly limited in the number of terminals, passive elements, active elements, or the like as long as the terminals of the electronic component are exposed on the surface of the component. In this specification, a mounting form and characteristics will be described in detail by taking an electronic component having two terminals as an example. Examples of the two-terminal element include a resistor, a capacitor, and a coil.

[Conductive paste application method]
As a method for applying the conductive paste, general known techniques such as screen printing, dispensing, and transfer can be used, but screen printing is preferable from the viewpoint of mass productivity.

[Component mounting structure]
The component mounting board obtained by the manufacturing method of the present embodiment is not limited to the following, but as examples of mounting a two-terminal element (for example, a capacitor, a resistor chip, etc.), FIGS. Illustrated in the figure. 4 to 8, (a) to (d) show (a) an electrode pattern of the circuit board 1 using the conductive paste 5 used in the present embodiment, (b) after printing the conductive paste, (c ) After component placement, (d) represents the component bonding state after heat treatment. 4 to 8 (d '), after using the same solder (Sn-3.5Ag-0.5Cu composition) paste as in (a) to (d) in each figure. It is the schematic of a component joining state. FIG. 4 shows an example in which a plurality of components are joined in parallel, FIG. 5 shows an example of combined mounting in parallel and series, and FIG. 6 shows that one end of the two-terminal element 7 is joined by one joint and the other end is another joint. 7 is an example in which a plurality of component mounting directions are different, and FIG. 8 is an example in which a plurality of components are joined in series. In any of the mounting examples, when a general solder paste is used ((d ′) in FIGS. 4 to 8), the position of the component moves randomly due to the surface tension of the molten solder particles before and after the heat treatment, and the shape of the component joint portion. Therefore, it is difficult to apply in mass production because problems such as concern about connection stability, restrictions on substrate design due to component flow, and optical inspection after heat treatment become difficult. On the other hand, when the manufacturing method of the present embodiment is used, the flow of parts is suppressed before and after heat treatment, and a stable joint shape can be obtained. Therefore, it is possible to design a circuit board that has been considered to be high-density packaging.

[Heat treatment process]
As a heat treatment method, a known one can be used in the component mounting process, for example, a reflow apparatus using IR, hot air, etc., or an oven, a hot plate, laser heating, etc. can be used. Or a reflow apparatus is preferable from a viewpoint of high productivity in a line type. The heat treatment temperature may be 10 ° C. higher than the melting point of the solder particles having the lowest melting point contained in the conductive paste and lower than the melting point of the refractory metal particles, and the substrate may be subjected to heat treatment that suppresses damage as much as possible. preferable. For example, when using a conductive paste containing Sn particles (melting point 232 ° C.) and Cu particles to mount components on the substrate electrode of the glass epoxy substrate (FR4), the melting point of the Sn particles is 10 ° C. or higher, for example about 250 ° C. Heat treatment is preferably performed at the peak temperature.

<Component mounting board>
A step of applying a conductive paste on a plurality of electrodes on a circuit board; a step of disposing at least a part of at least two electronic components on one electrode to which the conductive paste is applied; and the conductive paste A part mounting step of bonding a part of the at least two electronic components to the one electrode by heat treatment to form a bonding part,
The conductive paste includes solder particles, refractory metal particles having a melting point higher than that of the solder particles, and flux, or composite metal particles obtained by solder plating the surface of the refractory metal particles and flux, and The component mounting board manufactured by the method, wherein a relative position of a part of the at least two electronic components with respect to the one electrode does not change before and after the heat treatment, and the joint includes Sn A solder matrix containing refractory metal particles containing at least one metal selected from the group consisting of Cu, Ag, Ni, and Au, the melting point of the refractory metal particles being At least one selected from the group consisting of Cu, Ag, Ni, and Au is provided on the surface of the refractory metal particles that is higher than the melting point of the solder matrix. Genera and intermetallic compound phase containing Sn is present also relates to the component mounting board.

  The details of the electronic component, the circuit board and its electrode, the refractory metal particles, and the intermetallic compound phase are as described in the component mounting board manufacturing method of the present embodiment described above. The solder matrix containing Sn is Sn It is preferable that the composition or Sn alloy composition containing one or more metals selected from the group consisting of Sn and Ag, Bi, Cu, Ge, Ga, In, Sb, Ni, Zn, Pb, and Au, Specifically, Sn-Bi system, Sn-In system, Sn-Cu system, Sn-Zn system, Sn-Ag system, Sn-Au system, Sn-Pb system, Sn-Sb system, Sn-Bi-Ag Type, Sn-Ag-Cu type, Sn-Bi-Cu type, Sn-Zn-Bi type, Sn-Bi-In type, Sn-Ag-In type, Sn-Ag-In-Bi type, Sn-Cu- Ni-based, Sn-Cu-Ni-Ge-based, Sn-Ag Cu-Ni-Ge composition system can be exemplified.

The intermetallic compound phases include Cu—Sn (Cu ₃ Sn, Cu ₆ Sn ₅ ), Cu—Sn—Ni, Sn—Ni, Ag—Sn, Au—Sn (Ag ₃ Sn), Cu—Sn. -In, Cu-Sn-Ge, Cu-Sn-In-Ge, etc. can be illustrated.

  In addition, since the component mounting board of the present embodiment can extremely reduce the interval between electronic components, the signal wiring length is shortened compared to the component mounting board obtained by the conventional mounting method. Therefore, it is possible to improve the electrical characteristics, and it has a great merit for the downsizing of electronic devices. Furthermore, the joint has high remelting resistance against repeated reflow and the like. From the above, application to a module obtained by resin molding the obtained component mounting board is preferable. Moreover, application to a component-embedded substrate in which the component mounting substrate obtained in the present embodiment is laminated with a prepreg or an inner layer wiring substrate is also preferable for the above reason.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to this.

  The average particle diameter of each metal particle was determined as an average particle diameter value by measuring a volume integrated average value with a laser diffraction particle size distribution measuring device “HELOS & RODOS” manufactured by Sympatec (Germany).

  The melting point of the solder particles was measured at a measurement temperature range of 30 to 600 ° C. under a nitrogen atmosphere under a temperature increase of 10 ° C./minute using “DSC-60” manufactured by Shimadzu Corporation. The melting point.

[Example 1]
A verification experiment was conducted using the following solder particles.
(1) Solder particles A
Sn 10.0 kg (purity 99% by mass or more) was put in a graphite crucible and heated and melted to 1400 ° C. with a high-frequency induction heating apparatus in a helium atmosphere of 99% by volume or more.
Next, after introducing this molten metal from the tip of the crucible into a spray tank in a helium gas atmosphere,
Helium gas (purity 99% by volume or more, oxygen concentration less than 0.1% by volume, pressure 2.5 MPa) was ejected from a gas nozzle provided in the vicinity of the crucible tip, and Sn particles were produced. The cooling rate at this time was 2600 ° C./second.
When the obtained Sn particles were observed with a scanning electron microscope (Hitachi, Ltd .: S-3400N), they were spherical. The Sn particles were classified using an airflow classifier (Nisshin Engineering: TC-15N) at a setting of 5 μm, and after collecting the large particles, they were classified again at a setting of 40 μm, and the small particles were collected. The collected Sn particles were measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), and the average particle size was 6.9 μm.
Next, when the melting point of Sn particles was measured with a differential scanning calorimeter (Shimadzu Corporation: DSC-50), it was confirmed that the melting point was 232 ° C.

(2) High melting point metal particles Cu 6.5 kg (purity 99% by mass or more), Sn 1.5 kg (purity 99% by mass or more), A
g 1.0 kg (purity 99% by mass or more), Bi 0.5 kg (purity 99% by mass or more), and I
n0.5 kg (purity 99% by mass or more) was put in a graphite crucible and heated and melted to 1400 ° C. with a high-frequency induction heating apparatus in a helium atmosphere of 99% by volume or more.
Next, after introducing this molten metal from the tip of the crucible into a spray tank in a helium gas atmosphere,
Helium gas (purity 99 volume% or more, oxygen concentration less than 0.1 volume%, pressure 2.5 MPa) is ejected from a gas nozzle provided in the vicinity of the crucible tip and atomized to produce a Cu alloy powder (Cu65Ag10Bi5In5Sn15 powder). did. The cooling rate at this time was 2600 ° C./second.
This Cu alloy particle is used as an airflow classifier (Nisshin Engineering: TC-15N).
After classification at a setting of 0 μm and collecting the large particle side, classification was performed again at a setting of 30 μm and the small particle side was collected. Laser alloy particle size distribution analyzer (HELOS & RODO)
When measured in S), the average particle size was 15.1 μm. When the obtained Cu alloy particles were measured with a differential scanning calorimeter under the above measurement conditions, endothermic peaks were detected at 502 ° C. and 521 ° C.

(3) Conductive paste The solder particles and the refractory metal particles are mixed at a mass ratio of 100: 300 to produce a metal filler, and then a general solder for 89.3 mass% of the metal filler. A rosin-based flux of 10.7% by mass used for the paste was mixed, and the mixture was sequentially applied to a solder softener (Malcom: SPS-1) and a defoaming kneader (Matsuo Sangyo: SNB-350) to prepare a conductive paste.

(4) Component melt flow characteristics On the Cu electrode 3 of the circuit board 1 (board A) made of the high heat-resistant epoxy resin glass cloth shown in FIG. Using a printing machine (YVP-Xg-w) manufactured by Yamaha Motor Co., Ltd., printing was applied using a mask having an opening corresponding to the printing pattern (printing pattern A) shown in FIG. The figure in this specification is a diagram in which the conductive paste 5 is applied to the center of the substrate electrode 3. A 80 μm thick metal mask was used as the printing mask, the printing speed was 10 mm / second, and printing was performed using a metal squeegee. Thereafter, a 0603 (0.6 mm × 0.3 mm) size 0Ω resistance component 8 (hereinafter referred to as 0603R) is shown in FIG. 9C using a mounter device (YS12) manufactured by Yamaha Motor Co., Ltd. Thus, 20 pieces were arranged in parallel so that the gap GapI between components was 0.15 mm, and N2 reflow (O2 concentration: 1000 ppm or less) was performed to obtain an evaluation sample. In the present specification and the chart, as shown in FIG. 10, the component short side direction is calculated from the position coordinates and component size (for example, 0.6 mm × 0.3 mm) when the component is placed by the mounter device. Gap is denoted as GapI, and Gap in the component long side direction is denoted as GapII. As a heat treatment apparatus, ATEC Techtron Co., Ltd. (NIS-20-82C) was used. In the temperature profile, the temperature was increased from the start of heat treatment (normal temperature) to 140 ° C. at 2.0 ° C./second, from 140 ° C. to 170 ° C. over 150 seconds, and from 170 ° C. to a peak temperature of 250 ° C. at 2 ° C./second. A temperature profile was adopted in which the temperature was raised in seconds and maintained at 240 ° C. or higher for 30 seconds. The component mounting board after the heat treatment is observed with a digital microscope (VHX-500) manufactured by KEYENCE, and the components flow during the heat treatment, and are fused with adjacent components, and the end portions of the components are in contact with each other. When counting the number, it was 0 out of 20. This result is described in the part flow rate in Table 1.

[Examples 2 to 7, Comparative Example 1]
In Example 1, the mixing ratio of the solder particles and the refractory metal particles was changed to the ratio shown in Table 1, and the other component flow characteristics were measured under the same conditions. The evaluation results are shown in Table 1. In Example 7 only, the components to be placed were evaluated using a 0603 size capacitor (0603C). From this result, it is understood that the component flow is effectively suppressed as the refractory metal particles are added to the conductive paste.

[Examples 8 to 12]
The high melting point metal particles in Example 1 were changed to Cu powder, and the same evaluation as in Example 1 was performed with the metal filler composition shown in Table 2. Cu-HWQ made from Fukuda metal foil powder industry company was used for Cu powder used. The average particle diameter of the Cu powder was 15 μm.

[Examples 13 to 17]
The high melting point metal particles in Example 1 were changed to Ag powder, and the same evaluation as in Example 1 was performed with the metal filler composition shown in Table 3. As the used Ag powder, HXR-Ag manufactured by Nippon Atomizing Co., Ltd. was used. The average particle size of the Ag powder was 5.3 μm.

[Examples 18 to 19]
The high melting point metal particles in Example 1 were changed to Ni powder, and the same evaluation as in Example 1 was performed with the metal filler composition shown in Table 4. As the Ni powder used, SFR-Ni manufactured by Nippon Atomizing Co., Ltd. was used. The average particle size of the Ni powder was 10.1 μm.

[Examples 20 to 22]
In Example 3, the solder particles are Sn-3.0Ag-0.5Cu powder (Example 20), Sn-3.5Ag powder (Example 21), and Sn-58Bi powder (Example 22) shown below. The same evaluation as in Example 3 was performed. The evaluation results are shown in Table 5.
Sn-3.0Ag-0.5Cu powder: average particle size 30.3 μm, melting point 219 ° C.
Sn-3.5Ag powder: average particle diameter 20.1 μm, melting point 221 ° C.
Sn-58Bi powder: average particle size 35 μm, melting point 138 ° C.

  Only the temperature profile different from that in Example 3 was used in Example 22. The heat treatment apparatus uses Eitech Techtron Co., Ltd. (NIS-20-82C), and the temperature profile is increased from 110 ° C. to 2.0 ° C./second from the start of heat treatment (normal temperature) to 110 ° C. A temperature profile was adopted in which the temperature was raised to 130 ° C. over 150 seconds, the temperature was raised from 130 ° C. to a peak temperature of 160 ° C. at 2 ° C./second, and maintained at 160 ° C. for 45 s. At this time, the oxygen concentration was controlled at 1000 ppm.

[Examples 23 to 24, Comparative Example 2]
As the thermosetting resin flux, the following were evaluated. As a thermosetting resin composition, 90 parts by mass of an epoxy resin (AER260) manufactured by Asahi Kasei Epoxy Co., Ltd. which is a bisphenol A type epoxy resin, 5.0 parts by mass of adipic acid, and 6.0 parts by mass of triethanolamine were rotated. A thermosetting resin composition A was prepared by kneading for 5 minutes at room temperature (25 ° C.) using a revolutionary mixer (manufactured by THINKY Co., Ltd.) In this example, adipic acid having an average particle size of 3.4 μm was used.

  Solder particles and refractory metal particles are mixed at a ratio shown in Table 6 to prepare a metal filler, and then the thermosetting resin composition A 15% by mass is mixed with 85% by mass of the metal filler. , Solder softener (Malcom: SPS-1) and defoaming kneader (Matsuo Sangyo: SNB-350) were sequentially applied to produce a conductive paste. Thereafter, the component melt flow characteristics were evaluated in the same manner as in Example 1. The solder particles used were the Sn-3.0Ag-0.5Cu powder, and the refractory metal particles were the Cu powder. However, the heat treatment uses Yamato Seisakusho (NRY-325-5Z), and the temperature profile is raised from 120 ° C. to 120 ° C. at a temperature of 1.0 ° C./second from the start of heat treatment (normal temperature) to 120 ° C. A temperature profile was adopted in which the temperature was raised to 260 ° C. at a temperature of 260 ° C./second and a holding time of 220 ° C. or higher was 125 seconds.

[Examples 25 to 26, Comparative Example 3]
As the thermosetting resin flux, the following were evaluated. As thermosetting resin composition, 5.5 parts by mass of epoxy resin (AER260) manufactured by Asahi Kasei Epoxy Co., Ltd., which is a bisphenol A type epoxy resin, and 37 masses of epoxy resin (YL983U) manufactured by Mitsubishi Chemical Co., Ltd., which is a bisphenol F type epoxy resin. Part, 2-phenylimidazole isocyanuric acid adduct (2PZ-OK) 3 parts by mass, 0.5 parts by mass of n-butylamine, 3 parts by mass of adipic acid, A thermosetting resin composition B was prepared by kneading at room temperature (25 ° C.) for 5 minutes using a revolving mixer (THINKY Co., Ltd., Aritori Kentaro) and degassing for 3 minutes.

  Solder particles and refractory metal particles are mixed at a ratio shown in Table 7 to produce a metal filler, and then the thermosetting resin composition B 15% by mass is mixed with 85% by mass of the metal filler, Solder softener (Malcom: SPS-1) and defoaming kneader (Matsuo Sangyo: SNB-350) were sequentially applied to produce a conductive paste. Thereafter, the component melt flow characteristics were evaluated in the same manner as in Example 1. The solder particles used were the Sn-58Bi powder, and the refractory metal particles were the Cu powder. However, the heat treatment conditions were manufactured by Atec Techtron Co., Ltd. (NIS-20-82C), and the temperature profile was raised from the start of heat treatment (room temperature) to 160 ° C. at a rate of 2.0 ° C./second, and 160 ° C. The temperature profile held for 360 seconds was adopted. The oxygen concentration in the heat treatment atmosphere was 1000 ppm or less.

[Examples 27 to 34, Comparative Examples 4 to 7]
A conductive paste was prepared in the same manner as in Example 1 with the ratio of solder particles and refractory metal particles described in Table 8, and the component flow characteristics were evaluated in the same manner as in Example 1. The solder particles and the high melting point metal particles used were the Sn powder, the Sn-3.0Ag-0.5Cu powder, and the Cu65Ag10Bi5In5Sn15 powder. However, printing with an opening corresponding to the printing pattern (printing pattern B) shown in FIG. 11 (b) using the circuit board 1 (board B) made of the high heat-resistant epoxy resin glass cloth shown in FIG. 11 (a). The conductive paste 5 was printed using a mask, set to GapI and GapII shown in FIG. 11C, and 0603R was mounted as a component (reference numeral 8 in FIG. 11). Other conditions are the same as in the first embodiment.

  FIG. 12A shows an appearance after mounting of Comparative Example 7 in which the gap between components is mounted at a setting of 0.05 mm as a result of evaluating the component flow characteristics. FIG. 12B shows the appearance after the heat treatment. Further, FIG. 13 (a) shows the appearance after mounting the component of Example 34 mounted with a gap between components set to 0.05 mm, and the appearance after the heat treatment. When such a special manufacturing method is used with a conventional general solder paste, the component flows randomly during the heat treatment as shown in FIG. 12, so that it is extremely difficult to apply to mass production. is there. On the other hand, if the component mounting board manufacturing method of the present invention is used, it is understood that component mounting with a very narrow gap is possible as shown in FIG. For example, when a 0603 size component is mounted by a conventional circuit board design, a gap of about 0.12 mm is generally provided even if the gap between components is small. By using this manufacturing method, it can be said that higher-density mounting becomes possible.

[Examples 35 to 37, Comparative Examples 8 to 9]
A conductive paste was prepared in the same manner as in Example 1 with the ratio of solder particles and refractory metal particles described in Table 9, and the component flow characteristics were evaluated in the same manner as in Example 1. The solder particles and the high melting point metal particles used were the Sn powder, the Sn-3.0Ag-0.5Cu powder, and the Cu65Ag10Bi5In5Sn15 powder. However, using the circuit board 1 (substrate C) made of the high heat-resistant epoxy resin glass cloth shown in FIG. 14A, printing having an opening corresponding to the printing pattern (printing pattern C) shown in FIG. Using the mask, the conductive paste 5 was printed, and as shown in FIG. 14C, GapII was set to be 0.10 mm, and 48 0603R components 8 were arranged in series on a straight line. Thereafter, heat treatment was performed under the same conditions as in Example 1. The appearances of the part joints after heat treatment regarding Examples 36 and 37 are shown in FIGS. 15 (a) and 15 (b), respectively. Moreover, the external appearance of the component joint part after the heat treatment of Comparative Example 9 is shown in FIG. As can be seen from these appearances, when the conventional Pb-free solder paste is used, the melted solder component wets unevenly with respect to the adjacent component electrodes as shown in FIG. The joining state varies greatly at each end. On the other hand, as shown in FIGS. 15A and 15B, it can be seen that the component mounting board manufactured by the manufacturing method of the present invention has a stable bonding shape. Regarding the variation in the component joining shape, the cross-sectional polishing of the dotted line (with respect to the component short side direction) in FIG. 14C is performed to remove the electronic components at both ends of the 48 components 8 joined in series. The following evaluation was performed on 46 parts 8. As shown in FIG. 16, the heights T1 and T2 from the surface of the Cu electrode 3 are measured for the most depressed portion of the joint portion of both terminals of the two-terminal element (0603R) 8, and the absolute value of T1−T2 is When the thickness is 25% or more with respect to the component thickness (0603R component thickness: 0.23 mm), it is determined that the component bonding shape variation is large, and among 46 electronic components, the number of components with large component bonding shape variation is determined. It counted and described in the component joining shape dispersion | variation of Table 9.

  The present invention achieves high-density mounting, which is remarkably advanced particularly in the field of modules and the like, and is useful for manufacturing smaller modules and the like.

DESCRIPTION OF SYMBOLS 1 Circuit board 2 Solder resist 3 Board | substrate (Cu) electrode 4 Wiring 5 Solder (conductive) paste 6 Electronic component 7 2 terminal element 8 0603 size component (resistor chip)
w ₁ electrode width w ₂ electrode width w ₃ electrode width w ₄ electrode width w ₅ electrode width x ₁ paste printing width x ₂ paste printing width x ₃ paste printing width x ₄ paste printing width x ₅ paste printing width x ₆ paste printing width y Interelectrode gap T1 Distance from substrate (Cu) electrode T2 Distance from substrate (Cu) electrode

Claims (22)

The following steps:
Applying a conductive paste on a plurality of electrodes on a circuit board;
Disposing a part of at least two electronic components on one electrode coated with the conductive paste; and heat treating the conductive paste to convert a part of the at least two electronic components to the electrode. Joining to one electrode to form a joint;
A component mounting board manufacturing method including:
The conductive paste contains solder particles, refractory metal particles having a higher melting point than the solder particles, and flux, or
The method comprising: composite metal particles obtained by solder plating the surface of the refractory metal particles, and a flux. The following steps:
Applying a conductive paste on a metal surface in a plurality of predetermined regions on the substrate;
Disposing a part of at least two electronic components in one predetermined region to which the conductive paste is applied;
Bonding a part of the at least two electronic components to a metal surface in the one predetermined region by heat-treating the conductive paste to form a joint; and outside the predetermined region of the metal surface; Selectively etching to form a wiring pattern made of metal remaining in the predetermined region;
A component mounting board manufacturing method including:
The conductive paste contains solder particles, refractory metal particles having a higher melting point than the solder particles, and flux, or
The method comprising: composite metal particles obtained by solder plating the surface of the refractory metal particles, and a flux.   The component mounting board manufacturing method according to claim 1, wherein the electronic component is a two-terminal element.   The component mounting board manufacturing method according to claim 3, wherein both ends of the two-terminal element are joined to an electrode on a circuit board or a metal surface by the different joints.   The refractory metal particles according to any one of claims 1 to 4, wherein the refractory metal particles are refractory metal particles having a melting point of 280 ° C or higher, including at least one metal selected from Cu, Ag, Ni, and Au. Component mounting board manufacturing method.   The component mounting board manufacturing method according to claim 5, wherein the refractory metal particles further include In and / or Ge.   The solder particles or the solder plating is Sn composition or at least one selected from the group consisting of Sn and Ag, Bi, Cu, Ge, Ga, In, Sb, Ni, Zn, Pb, and Au. The component mounting board manufacturing method according to claim 1, which has a Sn alloy composition containing a metal.   The component mounting board manufacturing method according to claim 1, wherein the conductive paste includes 17 parts by mass or more of the refractory metal particles with respect to 100 parts by mass of the solder particles.   The component mounting board manufacturing method according to claim 1, wherein the flux includes at least one of an organic acid, an amine compound, and a halogen compound.   The component mounting board manufacturing method according to claim 9, wherein the flux further includes a thermosetting resin.   The component mounting board manufacturing method according to claim 10, wherein the flux further includes a curing agent. The following steps:
Applying a conductive paste on a plurality of electrodes on a circuit board;
Disposing a part of at least two electronic components on one electrode coated with the conductive paste; and heat treating the conductive paste to convert a part of the at least two electronic components to the electrode. Joining to one electrode to form a joint;
Including
The conductive paste is solder particles, high melting point metal particles having a melting point higher than the solder particles, and flux, or
The component mounting board manufactured by the component mounting board manufacturing method including the composite metal particles obtained by solder plating the surface of the refractory metal particles and the flux, and the joint portion has a solder matrix containing Sn, The solder matrix includes refractory metal particles containing at least one metal selected from the group consisting of Cu, Ag, Ni, and Au, and the melting point of the refractory metal particles is higher than the melting point of the solder matrix. The component having a high and high melting point metal particle has an intermetallic compound phase containing Sn and at least one metal selected from the group consisting of Cu, Ag, Ni, and Au. Mounting board. The following steps:
Applying a conductive paste on a metal surface in a plurality of predetermined regions on the substrate;
Disposing a part of at least two electronic components in one predetermined region to which the conductive paste is applied;
Bonding a part of the at least two electronic components to a metal surface in the one predetermined region by heat-treating the conductive paste to form a joint; and outside the predetermined region of the metal surface; Selectively etching to form a wiring pattern made of metal remaining in the predetermined region;
Including
The conductive paste contains solder particles, refractory metal particles having a higher melting point than the solder particles, and flux, or
A component mounting board manufactured by a component mounting board manufacturing method including a composite metal particle having a solder plating on the surface of the refractory metal particles and a flux, wherein the joint has a solder matrix containing Sn, and the solder The matrix includes refractory metal particles containing at least one metal selected from the group consisting of Cu, Ag, Ni, and Au, the melting point of the refractory metal particles being higher than the melting point of the solder matrix, In addition, the component mounting board, wherein at least one metal selected from the group consisting of Cu, Ag, Ni, and Au and an intermetallic compound phase containing Sn are present on the surface of the refractory metal particles .   The component mounting board according to claim 12 or 13, wherein the electronic component is a two-terminal element.   The component mounting board according to claim 14, wherein both ends of the two-terminal element are joined to an electrode on a circuit board or a metal surface by the different joints.   The component mounting board according to claim 15, wherein two or more two-terminal elements are joined in parallel.   17. The refractory metal particle according to claim 12, wherein the refractory metal particle is a refractory metal particle having a melting point of 280 ° C. or higher and containing at least one metal selected from Cu, Ag, Ni, and Au. Component mounting board.   The component mounting board according to claim 17, wherein the refractory metal particles further include In and / or Ge.   The solder matrix includes Sn composition or Sn and at least one metal selected from the group consisting of Ag, Bi, Cu, Ge, Ga, In, Sb, Ni, Zn, Pb, and Au. The component mounting board according to any one of claims 12 to 18, which has an alloy composition.   The intermetallic compound phase is any of Cu—Sn, Ni—Sn, Cu—Sn—Ni, Ag—Sn, Au—Sn, Cu—Sn—In, Cu—Sn—Ge or Cu—Sn—In—Ge. The component mounting board | substrate of any one of Claims 12-19 containing these.   The module which molded the component mounting board of any one of Claims 12-20 with the thermosetting resin.   A component built-in substrate obtained by laminating the component mounting substrate according to claim 12.