JP6130417B2 - Electronic component joining method, and solder composition and pretreatment agent used in the method - Google Patents

Description

The present invention relates to a method for joining electronic components, and a solder composition and a pretreatment agent used in the method.

2. Description of the Related Art In recent years, electronic devices have been miniaturized as printed wiring boards have become smaller and smaller, and mounting components mounted on printed boards have been further miniaturized. In order to join such fine parts at a fine pitch, it is required to finely pulverize conductive particles (such as solder powder) (for example, the average particle diameter is 20 μm or less).
However, when the solder powder has a small average particle diameter, the specific surface area increases, and the amount of oxide generated on the surface of the solder powder increases accordingly. In order to melt and remove the oxide generated on the surface of the solder powder, a solder composition having a flux component having a high reducing power is required. For example, an activator in the flux component has been studied. (For example, patent document 1).

JP 2006-110580 A

  However, when the number of active agents such as organic acids is increased, the insulation reliability and shelf life are reduced, and when the number of halogen-based active agents is increased, there is a problem of the amount of halogen in the composition. Thus, it is very difficult to cope with the pulverization of the conductive particles by the components in the conductive composition.

The present invention, while maintaining insulation reliability and shelf life of the solder composition, the bonding method of the electronic components that can improve the bonding property, and the solder composition and pretreatment agent used in the method The purpose is to provide.

In order to solve the above-mentioned problems, the present invention provides the following electronic component joining method.
That is, the electronic component joining method of the present invention includes a step of applying a pretreatment agent containing (X) an activator to an electronic component, and (A) a solder powder and (B) a resin on a substrate. A step of applying a solder composition containing a flux composition, and a step of mounting the electronic component on the substrate and performing a reflow treatment , wherein the flux composition comprises (C) an activator. When contained, the amount of the (C) activator is 6% by mass or less with respect to 100% by mass of the flux composition .

In the method for bonding electronic components of the present invention, it is preferable that the pretreatment agent further contains (Y) a solvent, and the (Y) solvent contains (Y1) a solvent having a boiling point of 100 ° C. or less.
In the method for joining electronic components of the present invention, the pretreatment agent further contains (Z) a curing component, and the (Z) curing component comprises (Z1) a resin curing agent and (Z2) a radical polymerization initiator. it is preferred from the group consisting of at least one selected.
In the method for joining electronic components of the present invention, it is preferable that the average particle diameter of the (A) solder powder is 20 μm or less.
In the electronic component joining method of the present invention, the solder composition may further contain (C) an activator.

Solder composition of the present invention, the a solder composition for use in the method of joining electronic parts, (A) the solder powder, and contains a flux composition containing the (B) resin, the flux composition is (C) When it contains an activator, the compounding quantity of the said (C) activator is 6 mass% or less with respect to 100 mass% of said flux compositions, It is characterized by the above-mentioned.
The pretreatment agent of the present invention is a pretreatment agent used in the method for joining electronic components, and contains (X) an activator.

In the method for bonding electronic components of the present invention, as described below, the bonding property can be improved while maintaining the insulation reliability and shelf life of the conductive composition.
Conventionally, electronic components are joined to a substrate using a conductive composition such as a solder composition. In such a case, the metal of the electrode of the electronic component can be activated by the flux component in the solder composition printed on the electrode of the substrate, so the electronic component is mounted on the substrate and the reflow process is performed. Thus, electronic components can be joined on the substrate. Thus, when joining an electronic component on a board | substrate using a solder composition, it was technical common sense to mount an electronic component on a board | substrate, without processing in particular. The present inventors have overturned such common technical knowledge and found that if a step of applying a specific pretreatment agent to an electronic component before mounting is performed, a great merit more than the demerit of labor required for the step can be obtained. It was.
That is, in the electronic component bonding method of the present invention, a pretreatment agent containing an activator is applied to the electronic component. And since the activator attached to the electrode of the electronic component can activate the metal of the electrode of the electronic component more directly than the activator in the solder composition, the activator in the solder composition is more than the amount of the activator. It is possible to efficiently improve the bondability. Surprisingly, the activator adhering to the electrode of the electronic component functions as the activator mixed in the solder composition as a flux component of the solder composition. The reason for this is not necessarily clear, but due to the flow of molten solder during the reflow process, the activator attached to the electrodes of the electronic component is sufficiently mixed in the solder composition and functions sufficiently as a flux component. The inventors speculate.
As described above, the joining property can be improved without increasing the total amount of the activator in the solder composition and the total amount of the activator attached to the electrode by the pretreatment agent. In addition, the amount of the activator in the solder composition can be reduced while maintaining the bondability. Therefore, according to the method for joining electronic components of the present invention, it is possible to improve the joining property while maintaining the insulation reliability and shelf life of the conductive composition.

According to the present invention, while maintaining insulation reliability and shelf life of the solder composition, the bonding method of the electronic components that can improve the bonding property, and the solder composition and pretreatment agent used in the method Can be provided.

It is explanatory drawing which shows an example of the joining method of the electronic component of this invention.

<Method of joining electronic parts>
DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a method for joining electronic components according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing an example of a method for joining electronic components according to the present invention.
As shown in FIG. 1, the electronic component bonding method of the present invention is a method for bonding an electronic component 1 to a substrate 2, and includes a pretreatment step (S 1) and a composition coating step (described below). S2) and a joining step (S3). In addition, although this embodiment demonstrates in order of a pre-processing process, a composition application | coating process, and a joining process, it is not limited to this order. The pretreatment process and the composition application process may be performed before the joining process, and the order of the pretreatment process and the composition application process is not limited. For example, the composition application step may be performed before the pretreatment step, or the pretreatment step and the composition application step may be performed simultaneously.

In the pretreatment step (S1), as shown in FIG. 1, the electronic component 1 is prepared (S1-1), and the pretreatment agent 3 is applied to the electronic component 1 (S1-2).
Examples of the electronic component 1 include BGA (ball grid array), QFN (Quad Flat No lead package), and chip components.
The electronic component 1 includes a component main body 11, an electrode 12, and a solder bump 13 provided on the electrode 12.
Although details will be described later, the pretreatment agent 3 contains (X) an activator.
The coating amount of the pretreatment agent 3 is not particularly limited, but the amount of (X) active agent attached per unit area is preferably 0.01 mg / cm ² or more and 1 mg / cm ² or less, 0.01 mg / cm ² More preferably, it is not less than cm ^{2 and not} more than 0.1 mg / cm ² . If the adhesion amount is less than the lower limit, activation of the metal of the electrode of the electronic component 1 tends to be insufficient, while if it exceeds the upper limit, the insulation reliability tends to decrease.

  Examples of the coating apparatus used here include a dip coater, a spray coater, a stamp, a screen printer, and a dispenser. Among these, a dip coater and a stamp are more preferable, and a stamp is particularly preferable from the viewpoint of easy application to a chip mounting apparatus.

In the pretreatment step (S1), the pretreatment agent 3 after application is dried as necessary (S1-3). As a result, the pretreatment agent 31 after drying containing the (X) activator adheres to the solder bumps 13 and the like of the electronic component 1.
The drying conditions are not particularly limited, but usually the drying temperature may be 15 ° C. or higher and 100 ° C. or lower and the drying time may be 1 second or longer and 60 seconds or shorter.

In the composition application step (S2), as shown in FIG. 1, a substrate 2 including a base material 21 and an electrode 22 is prepared (S2-1), and the conductive composition 4 is applied on the electrode 22 of the substrate 2. (S2-2).
Examples of the substrate 2 include a printed wiring board.
The conductive composition 4 contains (A) conductive particles and (B) resin, details of which will be described later.
Examples of the coating apparatus used here include a screen printer, a metal mask printer, a dispenser, and a jet dispenser.

In the bonding step (S3), as shown in FIG. 1, the electronic component 1 is mounted on the substrate 2 so that the electrode 12 of the electronic component 1 and the electrode 22 of the substrate 2 overlap in plan view (S3). -1) After that, a reflow process is performed, and the electronic component 1 is joined to the substrate 2 by the solder joint 5 (S3-2).
What is necessary is just to set reflow conditions suitably according to melting | fusing point of the solder which comprises the solder bump 13, or the electroconductive particle in the electroconductive composition 4. FIG. For example, when using a Sn—Ag—Cu-based solder alloy, preheating may be performed at a temperature of 150 to 200 ° C. for 60 to 120 seconds, and a peak temperature may be set to 230 to 270 ° C.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements and the like within a scope that can achieve the object of the present invention are included in the present invention.
For example, in the joining step, the electronic component 1 is joined on the substrate 2 by reflow processing, but the invention is not limited to this. For example, instead of the reflow process, the electronic component 1 may be bonded onto the substrate 2 by a process of heating the conductive composition using laser light (laser heating process). In this case, the laser light source is not particularly limited, and can be appropriately selected according to the wavelength matched to the metal absorption band. As the laser light source, for example, a solid laser (ruby, glass, YAG, etc.), semiconductor laser (GaAs, InGaAsP, etc.), (such as a dye) liquid laser, a gas laser (He-Ne, Ar, CO 2, etc. excimer) is Can be mentioned.

<Pretreatment agent>
Next, the pretreatment agent of the present invention will be described. That is, the pretreatment agent of the present invention is a pretreatment agent used in the method for joining electronic components and contains (X) an activator. Moreover, this pretreatment agent may contain a (Y) solvent and a (Z) curing component, if necessary.

[(X) component]
Examples of the (X) activator used in the present invention include organic acids, non-dissociative activators composed of non-dissociable halogenated compounds, and amine-based activators. These activators may be used individually by 1 type, and may mix and use 2 or more types. Among these, it is preferable to use an organic acid and an amine-based activator (containing no halogen) from the viewpoints of environmental measures and suppressing corrosion at the soldered portion.
Examples of the organic acid include other organic acids in addition to monocarboxylic acid and dicarboxylic acid.
Monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid Arachidic acid, behenic acid, lignoceric acid, glycolic acid and the like.
Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, tartaric acid, diglycolic acid and the like.
Examples of other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, and picolinic acid.

  Examples of the non-dissociative activator include non-salt organic compounds in which halogen atoms are bonded by a covalent bond. The halogenated compound may be a compound formed by covalent bonding of chlorine, bromine and fluorine, such as chlorinated, brominated and fluoride, but any two or all of chlorine, bromine and fluorine may be used. A compound having a covalent bond of In order to improve the solubility in an aqueous solvent, these compounds preferably have a polar group such as a hydroxyl group or a carboxyl group such as a halogenated alcohol or a halogenated carboxyl. Examples of the halogenated alcohol include 2,3-dibromopropanol, 2,3-dibromobutanediol, trans-2,3-dibromo-2-butene-1,4-diol, 1,4-dibromo-2-butanol, Brominated alcohols such as tribromoneopentyl alcohol, chlorinated alcohols such as 1,3-dichloro-2-propanol and 1,4-dichloro-2-butanol, fluorinated alcohols such as 3-fluorocatechol, and the like Compounds. Examples of the halogenated carboxyl include 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, 5-iodoanthranilic acid, etc., 2-chlorobenzoic acid, 3-chloropropion Examples thereof include carboxyl chloride such as acid, brominated carboxyl such as 2,3-dibromopropionic acid, 2,3-dibromosuccinic acid and 2-bromobenzoic acid, and other similar compounds.

  Examples of the amine activator include amines (polyamines such as ethylenediamine), amine salts (amines such as trimethylolamine, cyclohexylamine, diethylamine, and organic acid salts such as amino alcohols and inorganic acid salts (hydrochloric acid, sulfuric acid, odors). Hydroacid, etc.)), amino acids (glycine, alanine, aspartic acid, glutamic acid, valine, etc.), amide compounds and the like. Specifically, diphenylguanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine salt (hydrochloride, succinate, adipate, sebacate, etc.), triethanolamine, monoethanolamine, etc. And the hydrobromide of the amine.

  The pretreatment agent of the present invention may be the component (X) alone, but from the viewpoint of applicability, the component (X) is preferably dissolved in a solvent or the like. In such a case, the blending amount of the component (X) is preferably 0.1% by mass or more and 50% by mass or less, and 0.2% by mass or more and 20% by mass with respect to 100% by mass of the pretreatment agent. % Or less is more preferable.

[(Y) component]
As the solvent (Y) used in the present invention, a known solvent can be appropriately used. Such (Y) solvent can improve the applicability of the pretreatment agent. As the (Y) solvent, from the viewpoint of easy drying, (Y1) a solvent having a boiling point of 100 ° C. or less is preferable. Moreover, you may use together solvent other than (Y1) component as (Y) solvent.
Examples of the component (Y1) include methanol, ethanol, propanol, isopropyl alcohol, and tert-butyl alcohol. These solvents may be used alone or in combination of two or more. From the viewpoint of coating properties and drying properties, it is preferable to use a mixture of two or more, and it is particularly preferable to use a mixture of methanol, ethanol and isopropyl alcohol.

  The blending amount of the component (Y) is preferably 50% by mass or more and 99.9% by mass or less, and 80% by mass or more and 99% by mass with respect to 100% by mass of the pretreatment agent from the viewpoints of applicability and drying property. It is more preferable that the amount is not more than mass%.

[(Z) component]
Examples of the (Z) curing component used in the present invention include (Z1) a resin curing agent and (Z2) a radical polymerization initiator. These may be used alone or in combination of two or more. (Z) A component is a component for providing thermosetting, when the electroconductive composition mentioned later is thermosetting. (Z) When it mix | blends with an electroconductive composition, it causes a fall of shelf life. Therefore, if these (Z) components are contained in the pretreatment agent and mixed with the conductive composition during the reflow treatment, the (Z) component in the conductive composition can be reduced, and the conductivity The shelf life of the composition can be improved.

(Z1) As a resin hardening agent, a well-known hardening | curing agent can be used suitably. For example, when an epoxy resin is used as the thermosetting resin, the following can be used. One of these curing agents may be used alone, or two or more thereof may be mixed and used.
Examples of the latent curing agent include NOVACURE HX-3722, HX-3721, HX-3748, HX-3088, HX-3613, HX-392HP, HX-3941HP (trade name, manufactured by Asahi Kasei Epoxy), dicyandiamide (DICY). ) And the like.
Examples of the aliphatic polyamine curing agent include Fujicure FXR-1020, FXR-1030, FXR-1050, FXR-1080 (trade name, manufactured by Fuji Kasei Kogyo Co., Ltd.).
Examples of the epoxy resin amine adduct-based curing agent include Amicure PN-23, PN-F, MY-24, VDH, UDH, PN-31, and PN-40 (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name), EH-3615S. EH-3293S, EH-3366S, EH-3842, EH-3670S, EH-3636AS, EH-4346S, EH-5016S (trade name, manufactured by ADEKA).
Examples of the imidazole curing accelerator include 2P4MHZ, 1B2PZ, 2MZA, 2PZ, C11Z, C17Z, 2E4MZ, 2P4MZ, C11Z-CNS, and 2PZ-CNZ (trade names, manufactured by Shikoku Kasei Kogyo Co., Ltd.).

(Z2) Examples of the radical polymerization initiator include a thermal radical polymerization initiator and a photo radical polymerization initiator.
Examples of the thermal radical polymerization initiator include organic peroxides such as ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, and percarbonates. Is mentioned. These thermal radical polymerization initiators may be used alone or in combination of two or more. Of these thermal radical polymerization initiators, hydroperoxides are preferred from the viewpoint of balance between reactivity and stability, and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate is preferred. And t-butylperoxy-2-ethylhexanoate is more preferable.
Examples of the photo radical polymerization initiator include oxime initiators, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, and 2,2-dimethoxy. 2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (Methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzopheno 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, Examples include 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, and P-dimethylaminobenzoic acid ethyl ester. These radical photopolymerization initiators may be used alone or in combination of two or more.

  The blending amount of the component (Z) is preferably 0.1% by mass or more and 50% by mass or less with respect to 100% by mass of the pretreatment agent from the viewpoint of curability and coating property, and 0.3% by mass. More preferably, it is 10 mass% or less.

[Other ingredients]
In addition to the component (X), the component (Y) and the component (Z), other additives can be added to the pretreatment agent of the present invention as necessary. Examples of other additives include thixotropic agents and antifoaming agents.

<Conductive composition>
Next, the conductive composition of the present invention will be described. That is, the conductive composition of the present invention is a conductive composition used in the method for bonding electronic components, and contains (A) conductive particles and (B) a resin. Moreover, this electroconductive composition specifically, (A) electroconductive particle is disperse | distributed by using the flux composition containing (B) resin as a binder. The flux composition may contain (C) an activator, (D) a resin curing agent, (E) a radical polymerization initiator, and (F) a polymerizable compound as necessary.

[(A) component]
As (A) electroconductive particle used for this invention, if it is an electroconductive particle (powder), a well-known thing can be used suitably. As this (A) component, it is preferable to use solder powder from a viewpoint of the electroconductivity between electrodes. The solder powder preferably has a melting point of 240 ° C. or lower, and more preferably has a melting point of 180 ° C. or lower from the viewpoint of low-temperature processing. When the solder powder having a melting point exceeding 180 ° C. is used, the solder powder tends not to be melted when the temperature during reflow treatment is low (for example, 180 ° C. or lower). On the other hand, from the viewpoint of solder joint strength, the melting point of the solder powder is preferably 160 ° C. or higher, and more preferably 200 ° C. or higher.
Moreover, it is preferable that this solder powder is a lead-free solder powder from a viewpoint of the influence on an environment. Here, the lead-free solder powder refers to a solder metal or alloy powder to which lead is not added. However, it is allowed that lead is present as an inevitable impurity in the lead-free solder powder, but in this case, the amount of lead is preferably 100 mass ppm or less.

  The component (A) is a group consisting of tin (Sn), bismuth (Bi), copper (Cu), silver (Ag), antimony (Sb), indium (In), zinc (Zn), and titanium (Ti). It is preferably a metal or alloy made of at least one metal selected from the group consisting of: For example, tin-based solders include tin-copper such as Sn-0.7Cu; tin-silver such as Sn-3.5Ag; Sn-3.0Ag-0.5Cu, Sn-3.5Ag-0 Tin-silver-copper systems such as .7Cu, Sn-1.0Ag-0.7Cu, Sn-0.3Ag-0.7Cu; Sn-2.5Ag-1.0Bi-0.5Cu, Sn-1.0Ag Tin-silver-bismuth-copper system such as -2.0Bi-0.5Cu; Tin-silver-bismuth-indium system such as Sn-3.5Ag-0.5Bi-8.0In; Sn-1.0Ag-0 Tin-silver-copper-bismuth-indium system such as 7Cu-2.0Bi-0.2In; Tin-bismuth system such as Sn-58Bi; Tin-silver-bismuth system such as Sn-1.0Ag-58Bi; Sn-5 . Tin-antimony system such as 0Sb; S Tin-zinc system such as Sn-9Zn; Tin-zinc-bismuth system such as Sn-8.0Zn-3.0Bi; Tin-indium-antimony-zinc system such as Sn-30In-12Sb-3Zn; Sn-56Bi-4Ti Tin-bismuth-titanium system such as Sn-3.5Ag-4Ti; tin-silver-titanium system such as Sn-52In; tin-indium system such as Sn-52In. Examples of indium-based solder include indium-based metal indium; indium-silver-based such as In-3.0Ag. In addition to the above metals, iron (Fe), nickel (Ni), cobalt (Co), molybdenum (Mo), phosphorus (P), cerium (Ce), Germanium (Ge), silicon (Si), gallium (Ga), aluminum (Al), niobium (Nb), vanadium (V), calcium (Ca), magnesium (Mg), zirconium (Zr), gold (Au), Palladium (Pd), platinum (Pt), lead (Pb), etc. may be contained. Among these, tin-bismuth, tin-silver-bismuth, tin-indium, indium, indium-silver, and the like are more preferable from the viewpoint of low melting point characteristics. From the viewpoint of solder joint strength, tin-silver-copper, tin-silver, and the like are preferable.

  The average particle diameter of the component (A) is usually 1 μm or more and 40 μm or less, but is preferably 1 μm or more and 20 μm or less, more preferably 2 μm or more, from the viewpoint of corresponding to an electronic substrate having a narrow soldering pad pitch. More preferably, it is 15 m or less, and particularly preferably 3 μm or more and 12 μm or less. The average particle size can be measured with a dynamic light scattering type particle size measuring device.

[Flux composition]
The electrically conductive composition of this invention contains the flux composition demonstrated below and the said (A) component.
The blending amount of the flux composition is preferably 5% by mass to 35% by mass and more preferably 7% by mass to 15% by mass with respect to 100% by mass of the conductive composition (solder composition). Is more preferable, and it is particularly preferably 8% by mass or more and 12% by mass or less. When the blending amount of the flux composition is less than 5% by mass (when the blending amount of the solder powder exceeds 95% by mass), the flux composition as the binder is insufficient, so the flux composition and the solder powder are mixed. On the other hand, when the blending amount of the flux composition exceeds 35% by mass (when the blending amount of the solder powder is less than 65% by mass), when the obtained solder composition is used, It tends to be difficult to form a sufficient solder joint.

[Component (B)]
Examples of the (B) resin used in the present invention include (B1) rosin resin, (B2) thermosetting resin, and (B3) thermoplastic resin. Note that (B1) flux compositions using rosin resins (so-called rosin fluxes) do not have thermosetting properties, but (B2) flux compositions using thermosetting resins have thermosetting properties. Have.
Examples of the (B1) rosin resin include rosins and rosin modified resins. Examples of rosins include gum rosin, wood rosin, tall oil rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and derivatives thereof. As rosin-based modified resins, unsaturated organic acid-modified resins of the above rosins that can be reactive components of Diels-Alder reactions (aliphatic unsaturated monobasic acids such as (meth) acrylic acid, fumaric acid, maleic acid, etc.) adietic acids such as aliphatic unsaturated dibasic acids such as α, β-unsaturated carboxylic acids, and unsaturated carboxylic acids having an aromatic ring such as cinnamic acid) and abietic acids such as modified products thereof, and these The thing which has a modified substance as a main component is mentioned. These rosin resins may be used alone or in combination of two or more.

  The blending amount of the component (B1) is preferably 30% by mass to 70% by mass, and more preferably 35% by mass to 60% by mass with respect to 100% by mass of the flux composition. When the blending amount of the component (B1) is less than the lower limit, oxidation of the copper foil surface of the soldering land is prevented and the molten solder is easily wetted on the surface, so-called solderability is lowered, and solder balls are easily generated. On the other hand, if the upper limit is exceeded, the amount of residual flux tends to increase.

As the (B2) thermosetting resin, a known thermosetting resin can be used as appropriate. From the viewpoint of having a flux action, it is particularly preferable to use an epoxy resin.
In the present invention, having a flux action means that the coating film covers the metal surface of the object to be soldered and shields the atmosphere, like metal rosin flux, and the metal surface of the metal surface is oxidized during soldering. The material is reduced, and the coating film is pushed away by the molten solder to allow contact between the molten solder and the metal surface, and the residue has a function of insulating between the circuits.

  As such an epoxy resin, a known epoxy resin can be appropriately used. Examples of such epoxy resins include bisphenol A type, bisphenol F type, biphenyl type, naphthalene type, cresol novolac type, phenol novolac type, and dicyclopentadiene type epoxy resins. These epoxy resins may be used individually by 1 type, and may mix and use 2 or more types. Further, these epoxy resins preferably contain a liquid at normal temperature (25 ° C.), and when a solid is used at normal temperature, it is preferably used in combination with a liquid at normal temperature. In addition, among these epoxy resin molds, the dispersibility of the metal particles and the paste viscosity can be adjusted, and further, the resistance to the drop impact of the cured product can be improved, and the wettability of the solder can be improved. Liquid bisphenol A type, liquid bisphenol F type, liquid hydrogenated bisphenol A type, naphthalene type, dicyclopentadiene type, and biphenyl type are preferable, and liquid bisphenol A type, liquid bisphenol F type, and biphenyl type are more preferable.

  The blending amount of the (B2) thermosetting resin is preferably 50% by mass to 95% by mass and more preferably 80% by mass to 90% by mass with respect to 100% by mass of the flux composition. More preferred. If the blending amount of the thermosetting resin is less than the lower limit, sufficient strength for fixing the electronic component cannot be obtained, and thus the resistance to drop impact tends to be reduced. On the other hand, if the upper limit is exceeded, the flux composition The content of the curing component in the product is reduced, and the rate at which the thermosetting resin is cured tends to be delayed.

  Examples of the thermoplastic resin (B3) include polyester resins, polyurethane resins, polyester urethane resins, polyether resins, polyamide resins, polyamideimide resins, polyimide resins, polyvinyl butyral resins, polyvinyl formal resins, phenoxy resins, and polyhydroxypoly resins. Examples include ether resins, acrylic resins, polystyrene resins, butadiene resins, acrylonitrile / butadiene copolymers, acrylonitrile / butadiene / styrene copolymers, styrene / butadiene copolymers, and acrylic acid copolymers. These thermoplastic resins may be saturated or unsaturated. Moreover, these thermoplastic resins may be used individually by 1 type, and 2 or more types may be mixed and used for them. Among these thermoplastic resins, saturated polyester resins, unsaturated polyester resins, and phenoxy resins are preferable from the viewpoint of the adhesive strength of the obtained conductive composition.

  The weight average molecular weight of the component (B3) is preferably from 20,000 to 500,000, more preferably from 30,000 to 250,000, from the viewpoint of fluidity of the thermoplastic resin. More preferably, it is 40,000 to 100,000, and particularly preferably 50,000 to 80,000. In the present specification, the weight average molecular weight is a value measured by gel permeation chromatography and converted using a standard polystyrene calibration curve.

  The blending amount of the component (B3) is preferably 8% by mass to 35% by mass, more preferably 10% by mass to 30% by mass, with respect to 100% by mass of the flux composition. It is particularly preferable that the content is not less than 25% by mass and not more than 25% by mass. When the blending amount of the component (B3) is less than the lower limit, the adhesive strength of the conductive composition tends to decrease. On the other hand, when the upper limit is exceeded, the viscosity of the obtained conductive composition increases, and the coatability is increased. Tend to decrease.

[Component (C)]
As the (C) activator used in the present invention, the same activator as (X) activator used for the pretreatment agent can be used. In addition, in the electroconductive composition of this invention, since the (X) activator of the said pre-processing agent can be utilized in the case of a reflow process, the compounding quantity of (C) component can be reduced. Moreover, in the electroconductive composition of this invention, it is not necessary to contain (C) component.

  When the component (C) is blended, the blending amount of the component (C) is preferably 1% by mass or more and 15% by mass or less, and preferably 3% by mass or more and 12% by mass with respect to 100% by mass of the flux composition. More preferably, it is more preferably 5% by mass or more and 10% by mass or less. When the blending amount of the component (C) is less than the lower limit, solder balls tend to be generated, and when the upper limit is exceeded, the insulating property of the conductive composition tends to be lowered.

[(D) component]
(D) The resin curing agent is used when (B2) thermosetting resin is used as the component (B). As this (D) component, the thing similar to the (Z1) resin hardening agent used for the said pretreatment agent can be used. In addition, in the electroconductive composition of this invention, since the (Z1) resin hardening | curing agent of the said pretreatment agent can be utilized in the case of a reflow process, the compounding quantity of (D) component can be reduced. Moreover, in the electroconductive composition of this invention, it is not necessary to contain (D) component.

  When the component (D) is blended, the blending amount of the component (D) is preferably 0.5% by mass or more and 15% by mass or less, and preferably 2% by mass or more and 10% by mass with respect to 100% by mass of the flux composition. It is more preferable that the amount is not more than mass%. When the blending amount of the component (D) is less than the lower limit, the rate at which the thermosetting resin is cured tends to be delayed, whereas when the upper limit is exceeded, the reactivity becomes faster and the pot life tends to be shorter. is there.

[(E) component]
(E) A polymerizable compound is used when (B3) a thermoplastic resin is used as the component (B). Since this component (E) can be cured by polymerization, it can impart thermosetting properties to the flux composition.
(E) The polymerizable compound has one or more unsaturated double bonds in one molecule, and specifically (E1) has two or more unsaturated double bonds in one molecule. It is a radically polymerizable resin or (E2) a reactive diluent having one unsaturated double bond in one molecule. As this (E) component, it is preferable to contain both the said (E1) component and the said (E2) component from a viewpoint of the balance of the adhesive strength of a conductive composition obtained, and applicability | paintability.

The (E1) radical polymerizable resin is a resin having two or more unsaturated double bonds in one molecule. The component (E1) is a radical polymerizable resin having a weight average molecular weight of 800 or more and having two or more (meth) acryloyl groups, for example. By adding an appropriate amount of the component (E1), the adhesive strength of the resulting conductive composition tends to be improved. Examples of the component (E1) include urethane acrylate resins, epoxy acrylate resins, and silicon acrylate resins. These may be used alone or in combination of two or more.
The weight average molecular weight of the component (E1) is preferably 1000 or more and 10,000 or less, and more preferably 1200 or more and 5000 or less.

  The blending amount of the component (E1) is preferably 5% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 45% by mass or less, with respect to 100% by mass of the flux composition. It is particularly preferable that the content be not less than 35% by mass and not more than 35% by mass. When the blending amount of the component (E1) is less than the lower limit, the adhesive strength of the obtained conductive composition tends to decrease. On the other hand, when the upper limit is exceeded, the viscosity of the obtained conductive composition increases. There exists a tendency for applicability | paintability to fall.

  The (E2) reactive diluent is a reactive diluent having one unsaturated double bond in one molecule. This component (E2) is liquid at room temperature (25 ° C.) and can dissolve thermoplastic resins and the like. Examples of the component (E2) include 2-hydroxy-3-phenoxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate. , Isobutyl (meth) acrylate, tert-butyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n-lauryl (meth) ) Acrylate, tridecyl (meth) acrylate, n-stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate Rate, 2-hydroxyethyl (meth) acrylate, isobornyl (meth) acrylate, (meth) acryloyl morpholine. These reactive diluents may be used alone or in a combination of two or more. Among these reactive diluents, tetrahydrofurfuryl acrylate is preferable from the viewpoint of the solubility of the thermoplastic resin and the adhesive strength.

  The blending amount of the component (E2) is preferably 15% by mass or more and 55% by mass or less, more preferably 20% by mass or more and 50% by mass or less, with respect to 100% by mass of the flux composition. It is particularly preferable that the content is not less than 40% by mass. When the blending amount of the component (E2) is less than the lower limit, the viscosity of the obtained conductive composition tends to be high, and the applicability tends to be reduced. On the other hand, when the amount exceeds the upper limit, The adhesive strength tends to decrease.

  The blending amount of the component (E) (the total blending amount of the component (E1) and the component (E2)) is 5% by mass or more and 60% by mass from the viewpoint of the balance of adhesive strength and applicability of the obtained conductive composition. % Or less, more preferably 10% by mass or more and 50% by mass or less, and particularly preferably 15% by mass or more and 40% by mass or less.

[(F) component]
(F) The radical polymerization initiator is used when (B3) a thermoplastic resin is used as the component (B). As this (F) component, the thing similar to the (Z2) radical polymerization initiator used for the said pretreatment agent can be used. In addition, in the conductive composition of this invention, since the (Z2) radical polymerization initiator of the said pre-processing agent can be utilized in the case of a reflow process, the compounding quantity of (F) component can be reduced. Moreover, in the electroconductive composition of this invention, it is not necessary to contain (F) component.

  When the component (F) is blended, the blending amount of the component (F) is preferably 0.01% by mass or more and 5% by mass or less with respect to 100% by mass of the flux composition, and 0.05% by mass. The content is more preferably 3% by mass or less, and particularly preferably 0.1% by mass or more and 1% by mass or less. When the blending amount of the component (F) is less than the lower limit, the reactivity in radical polymerization tends to decrease, and when it exceeds the upper limit, the shelf life of the conductive composition obtained tends to decrease.

[Other ingredients]
In addition to the component (B), the component (C), the component (D), the component (E), and the component (F), the flux composition used in the present invention includes other components as necessary. Additives can be added. Examples of other additives include solvents, thixotropic agents, antifoaming agents, antioxidants, modifiers, matting agents, and foaming agents.

[Method for producing conductive composition]
The conductive composition of the present invention can be produced by blending the above-described flux composition and the above-described (A) conductive particles at the predetermined ratio and stirring and mixing them.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these examples. In addition, the material used in the Example and the comparative example is shown below.
<Pretreatment agent>
((X) component)
Activator A: Adipic acid (component (Y))
Solvent A: Isopropyl alcohol solvent B: Methanol solvent C: Ethanol (component (Z))
Resin curing agent: Dicyandiamide <conductive composition>
((A) component)
Solder powder: average particle diameter 20 μm, solder melting point 216-220 ° C., solder composition Sn / Ag / Cu
((B) component)
Rosin resin: Hydrogenated acid-modified rosin, manufactured by Arakawa Chemical Industries, Ltd., trade name “Pine Crystal KE-604”
Thermosetting resin: Epoxy resin, manufactured by DIC, trade name “EXA-830LVP”
((C) component)
Activator A: Adipic acid Activator B: trans-2,3-dibromo-2-butene-1,4-diol (TDDB)
((D) component)
Resin hardener: Dicyandiamide (other ingredients)
Solvent D: 2-ethylhexyl diglycol

[Example 1]
Activator A 0.3% by mass, solvent A 9% by mass, solvent B 14% by mass and solvent C 76.7% by mass were charged into a container and mixed to obtain a pretreatment agent.
50% by mass of rosin resin, 5% by mass of Activator A, 1% by mass of Activator B, and 44% by mass of Solvent D were charged into a container and mixed using a roughing machine to obtain a flux composition. Thereafter, 12% by mass of the obtained flux composition and 88% by mass of solder powder (100% by mass in total) were put into a container and mixed in a kneader to prepare a conductive composition.
Then, the pretreatment agent obtained on the electronic component (chip component, size: 12 mm × 12 mm) was applied by a dip coater and dried at a temperature of 20 ° C. for 5 seconds. On the other hand, the obtained conductive composition was printed on a substrate (electrode pitch: 0.25 mm, electrode interval: 0.25 mm) using a mask (thickness: 80 μm) having a corresponding pattern. Thereafter, an electronic component is mounted, reflow treatment is performed under the conditions of preheating temperature of 150 to 200 ° C. for 90 to 120 seconds, holding time of 220 ° C. or higher for 30 to 60 seconds, and peak temperature of 240 ° C. Bonded to the substrate.

[Examples 2 to 6]
A pretreatment agent and a conductive composition were obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1 below.
Then, using the obtained pretreatment agent and conductive composition, the electronic component was bonded to the substrate in the same manner as in Example 1 except that the pretreatment agent was applied according to the pretreatment agent application method shown in Table 1 below. did.
[Comparative Examples 1-5]
A conductive composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1 below.
Then, the obtained conductive composition was printed on a substrate (electrode pitch: 0.25 mm, electrode interval: 0.25 mm) using a mask (thickness: 80 μm) having a corresponding pattern. Thereafter, electronic components (chip components, size: 12 mm × 12 mm) are mounted, the preheating temperature is 150 to 200 ° C. for 90 to 120 seconds, the holding time of 220 ° C. or higher is 30 to 60 seconds, and the peak temperature is 240 ° C. The electronic component was bonded to the substrate by performing a reflow process under the conditions.

<Evaluation of electronic component joining method>
Evaluation of electronic component joining methods (insulation reliability, shelf life, component bottom void, component joining) were performed by the following methods. The obtained results are shown in Table 1.
(1) Insulation reliability A wiring board having a circuit pattern (line / space = 5 mm / 320 μm, conductor thickness: 35 μm) was prepared. And the conductive composition was apply | coated on the land of this wiring board. Next, a corresponding 5 mm wide alloy piece (composition: Sn / Ag / Cu, size: 5 mm × 20 mm, thickness: 1 mm) was prepared, and a pretreatment agent was applied thereto according to the conditions. Then, it was placed on the conductive composition and melted by reflow treatment to obtain a test piece. The reflow processing conditions were the same as those in Example 1.
The obtained test piece was subjected to a migration test to measure an insulation resistance value. The migration test is performed in accordance with the method described in JIS Z 3284 appendix 6 (temperature 85 ° C., relative humidity 85%, 1000 hours).
And insulation reliability was evaluated according to the following reference | standard based on the insulation resistance value.
A: The insulation resistance value is 1 × 10 ⁹ Ω or more.
X: The insulation resistance value is less than 1 × 10 ⁹ Ω.
(2) Shelf life First, the viscosity is measured using the conductive composition as a sample. Thereafter, the sample is put in a sealed container, put into a constant temperature bath at a predetermined temperature, stored for 15 days, and the viscosity of the stored sample is measured. The predetermined temperature is 10 ° C. when the conductive composition is a rosin-based solder composition, and is −10 ° C. when the conductive composition is an epoxy-based solder composition. And the viscosity change rate [{(η2-η1) / η1} × 100%] of the viscosity value (η2) after storage for 15 days with respect to the viscosity value (η1) before storage is obtained. The viscosity is measured according to the method described in JIS Z 3284 appendix 6.
And shelf life was evaluated according to the following reference | standard based on the viscosity change rate.
A: Viscosity change rate is -5% or more and 5% or less.
○: Viscosity change rate is −20% or more and less than −5% or more than 5% and 20% or less
X: Viscosity change rate is less than -20% or more than 20%.
(3) Lower surface void of component A 0.5 mm pitch BGA (228 pin, manufactured by Amkor) and a wiring board having a circuit pattern corresponding to the BGA were prepared. And the conductive composition was apply | coated on the land of this wiring board. Next, a pretreatment agent was applied to the BGA according to conditions, then placed on the conductive composition, and melted by reflow treatment to obtain a test piece. The reflow processing conditions were the same as those in Example 1.
Using the X-ray inspection apparatus (“NLX-5000”, manufactured by NAGOYA ERETRIC WORKS), all the 228 pins are inspected, and the void area ratio is determined from the following calculation formula.
Void area ratio (%) = {(Bump area−Area with void in bump) / Bump area} × 100
And the lower surface void of components was evaluated according to the following reference | standard based on the void area ratio.
○: The void area ratio is 20% or more.
X: Void area ratio is less than 20%.
(4) Joining of parts A 0.5 mm pitch BGA (228 pin, manufactured by Amkor) and a wiring board having a circuit pattern corresponding to the BGA were prepared. And the conductive composition was apply | coated on the land of this wiring board. Next, a pretreatment agent was applied to the BGA according to conditions, then placed on the conductive composition, and melted by reflow treatment to obtain a test piece. The reflow processing conditions were the same as those in Example 1.
About the obtained test piece, the conduction | electrical_connection resistance value (four terminal measuring method) was measured.
Then, the joining of the components was evaluated according to the following criteria based on the conduction resistance value.
○: The conduction resistance value is less than 1Ω.
X: The conduction resistance value is 1Ω or more.

As is apparent from the results shown in Table 1, when the electronic component joining method according to the present invention is used (Examples 1 to 6), the insulation reliability, shelf life, the bottom void of the component, and the component All of the joints were good. Therefore, according to the present invention, it has been confirmed that the bondability can be improved while maintaining the insulation reliability and shelf life of the conductive composition.
On the other hand, when the step of applying the pretreatment agent to the electronic component is not performed (Comparative Examples 1 to 5), any one of insulation reliability, shelf life, component lower surface void, and component bonding It was found that the above evaluation was insufficient.
Further, the conductive compositions containing a large amount of the activator B (Comparative Examples 2 and 4) have a problem from the viewpoint of halogen-free.

  The electronic component joining method of the present invention can be particularly suitably used as a technique for mounting an electronic component on a printed wiring board of an electronic device.

DESCRIPTION OF SYMBOLS 1 ... Electronic component 2 ... Board | substrate 3 ... Pretreatment agent 4 ... Conductive composition

Claims (7)

Applying a pretreatment agent containing (X) an activator to an electronic component;
The substrate, (A) the solder powder, and a step of applying the solder composition containing a flux composition containing the (B) resin,
Mounting the electronic component on the substrate and performing a reflow process ,
When the flux composition contains (C) an activator, the blending amount of the (C) activator is 6% by mass or less with respect to 100% by mass of the flux composition. Electronic component joining method. In the joining method of the electronic components of Claim 1,
The pretreatment agent further contains (Y) a solvent,
Said (Y) solvent contains (Y1) solvent whose boiling point is 100 degrees C or less. The joining method of the electronic components characterized by the above-mentioned. In the joining method of the electronic component of Claim 1 or Claim 2,
The pretreatment agent further contains a (Z) curing component,
The method for joining electronic components, wherein the (Z) curing component is at least one selected from the group consisting of (Z1) a resin curing agent and (Z2) a radical polymerization initiator. In the joining method of the electronic components of any one of Claims 1-3,
(A) Average particle diameter of said solder powder is 20 micrometers or less. The joining method of the electronic components characterized by the above-mentioned. In the joining method of the electronic component of any one of Claims 1-4 ,
The solder composition further includes (C) an activator. An electronic component joining method, wherein: A solder composition used in the electronic component joining method according to any one of claims 1 to 5 ,
(A) a solder powder, and (B) a flux composition containing a resin ,
When the flux composition contains (C) an activator, the blending amount of the (C) activator is 6% by mass or less with respect to 100% by mass of the flux composition. Solder composition. A pretreatment agent used in the electronic component joining method according to any one of claims 1 to 5 ,
(X) A pretreatment agent comprising an activator.

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