JP6530734B2 - Thermosetting flux composition and method of manufacturing electronic substrate - Google Patents

Description

  The present invention relates to a thermosetting flux composition and a method of manufacturing an electronic substrate.

As electronic devices have become smaller and thinner, package parts having solder balls (for example, ball grid array package: BGA package) have been used. Although fine-pitched BGA packages are also required for such BGA packages, there is a problem that when joining fine-pitched BGA packages to a mounting substrate, the strength of the bonding portion is weak only with solder balls. Therefore, usually, the bonding portion is reinforced by filling and curing the underfill material between the BGA package and the mounting substrate. However, since it takes time to fill and cure the underfill material, there is a problem in terms of production cost.
On the other hand, a method has been proposed in which an adhesive containing a flux agent is printed in advance on a mounting substrate, and a package component is mounted on a printed portion (see Patent Document 1).

Unexamined-Japanese-Patent No. 4-280443

  In the method using the adhesive described in Patent Document 1, a cured product of the adhesive remains on the mounting substrate. Therefore, the cured product of the adhesive is also required to pass the same durability test (for example, thermal cycle test) as the material (such as solder resist) used for the mounting substrate. However, the cured product of the adhesive described in Patent Document 1 fails the thermal cycle test because of the low glass transition point.

  On the other hand, in order to increase the glass transition temperature of the cured product, there are a method of making the skeleton of the epoxy resin rigid and a method of increasing the curing rate of the epoxy resin. However, in the case of such a method, there is a problem that the solderability in reflow and the self-alignment are impaired. Further, as a method of improving the solderability and the self alignment property in the reflow, there are a method of making the skeleton of the epoxy resin flexible and a method of lowering the curing rate of the epoxy resin. However, in such a method, the glass transition temperature of the cured product is lowered. As described above, the glass transition point of the cured product, the solderability in reflow, and the self alignment property are in a trade-off relationship, and it has been difficult to improve both of them.

  Moreover, with the development of high-speed data communication in recent years, the use of devices in high frequency bands is increasing. And the conventional epoxy resin has a high dielectric loss tangent, and there also existed a problem of causing a delay of a signal, and a noise. Therefore, the cured product of the adhesive is also required to have low dielectric constant and dielectric loss tangent.

  Therefore, in the present invention, a thermosetting flux composition in which the glass transition point of the cured product is sufficiently high, the dielectric constant and dielectric loss tangent of the cured product are sufficiently low, and the solderability and self alignment properties in reflow are excellent. It is an object of the present invention to provide an article and a method of manufacturing an electronic substrate using the article.

In order to solve the above problems, the present invention provides the following thermosetting flux composition and method of manufacturing an electronic substrate.
That is, the thermosetting flux composition of the present invention is a thermosetting flux composition which does not contain conductive fine particles and is used when joining an electronic component having a solder bump to an electronic substrate by reflow soldering, and Mounting an electronic component having a solder bump made of a solder alloy having a melting point of 200 ° C. or more and 230 ° C. or less on a bonding land of the wiring substrate; Mounting step, a reflow step of melting the solder bumps by heating the wiring substrate on which the electronic component is mounted, and bonding the solder bumps to the bonding land, and the thermosetting flux composition A thermosetting flux composition for use in a method of manufacturing an electronic substrate, comprising: A) A thermosetting resin, (B) a curing agent, and (C) an activator, wherein the (A) component contains (A1) an epoxy resin and (A2) an active ester resin, and the above (A1) Component) is at least one selected from the group consisting of bisphenol A epoxy resins and naphthalene type epoxy resins, and the component (B) is at least one selected from the group consisting of (B2) imidazole-based curing agents And a (B3) pyridine-based curing agent, wherein the (B2) component is 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2, 4-Diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-methylimidazole -(1 ')-Ethyl-s-triazine, 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine isocyanuric acid adduct, 1-cyanoethyl-2- Phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-undecylimidazole, and 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl At least one member selected from the group consisting of -s-triazines, wherein the component (B3) is N, N-dimethyl-4-aminopyridine, N, N-diethyl-4-aminopyridine, 2-aminopyridine At least one member selected from the group consisting of 4-aminopyridine and 2,6-diaminopyridine, and the component (C) is an organic acid And the amine salt of the organic acid, wherein the organic acid is oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, and At least one selected from the group consisting of diglycolic acid, and the mass ratio (A1 / A2) of the component (A1) to the component (A2) is 1/1 or more and 2/1 or less; The blending amount of the component A) is 70% by mass or more based on 100% by mass of the thermosetting flux composition, and the cured product of the thermosetting flux composition has the following conditions (i) to (iii): It is characterized by satisfying all.
Condition (i): The glass transition point is 100 ° C. or more.
Condition (ii): The relative dielectric constant at 1 GHz is 2.5 or less.
Condition (iii): The dielectric loss tangent at 1 GHz is 0.005 or less.

In the thermosetting flux composition of the present invention, when the temperature is raised at a temperature rising rate of 25 ° C. to 5 ° C./min, the viscosity at a temperature of 200 ° C. is 5 Pa · s or less and the temperature at 250 ° C. The viscosity is preferably 50 Pa · s or more .

The method of manufacturing an electronic substrate of the present invention is a manufacturing method for an electronic substrate using the thermosetting flux composition onto a wiring substrate, a coating step of applying the thermosetting flux composition, melting point 200 A mounting step of mounting an electronic component having a solder bump formed of a solder alloy of at least 230 ° C. on a bonding land of the wiring substrate, and heating the wiring substrate on which the electronic component is mounted; And a thermosetting step of heating and curing the thermosetting flux composition to bond the solder bumps to the bonding lands.

According to the thermosetting flux composition of the present invention, the glass transition point of the cured product is sufficiently high, the dielectric constant and dielectric loss tangent of the cured product are sufficiently low, and the solderability and self-alignment property in reflow are obtained. Although the reason for being excellent is not necessarily clear, the present inventors speculate as follows.
That is, the thermosetting flux composition of the present invention uses a curing agent (B) such that curing of the thermosetting flux composition does not progress so much in the reflow step. Therefore, the flowability of the molten solder is not hindered by the cured product of the thermosetting flux composition, so that the solderability and the self alignment property in the reflow can be maintained. On the other hand, since the thermosetting flux composition of the present invention can be sufficiently cured in the thermosetting process after the reflow process, the glass transition point of the cured product can be sufficiently high. Furthermore, the (A2) active ester resin can satisfy the curing conditions as described above, and can lower the dielectric constant and the dielectric loss tangent more than the cured product of the (A1) epoxy resin alone. The inventors speculate that the effects of the present invention can be achieved as described above.

  According to the present invention, a thermosetting flux composition in which the glass transition point of the cured product is sufficiently high, the dielectric constant and dielectric loss tangent of the cured product are sufficiently low, and the solderability and self alignment performance in reflow are excellent. It is possible to provide an article and a method of manufacturing an electronic substrate using the article.

[Thermosetting flux composition]
First, the thermosetting flux composition of the present invention will be described.
The thermosetting flux composition of the present invention is a thermosetting flux composition used when joining an electronic component having a solder bump to an electronic substrate by reflow soldering, and is described below (A) thermosetting It contains a resin, (B) a curing agent and (C) an activator.

In the thermosetting flux composition of the present invention, when the temperature is raised at a temperature rising rate of 25 ° C. to 5 ° C./min, the viscosity at a temperature of 200 ° C. is 5 Pa · s or less and the temperature at 250 ° C. The viscosity is preferably 50 Pa · s or more. When the viscosity at a temperature of 200 ° C. exceeds 5 Pa · s, the curing of the thermosetting flux composition proceeds too much, and the fluidity of the molten solder is impeded, so that the solderability and reflowability in the reflow process are improved. It tends to decline. On the other hand, when the viscosity at a temperature of 250 ° C. is less than 50 Pa · s, the curing property of the thermosetting flux composition is insufficient, and the glass transition temperature of the cured product tends to be lowered.
Here, the viscosity can be measured by a rheometer. Specifically, the viscosity can be measured under predetermined conditions using a rheometer (manufactured by HAAKE, trade name "MARS-III").

Further, the glass transition point of the cured product of the thermosetting flux composition of the present invention is preferably 100 ° C. or more, more preferably 120 ° C. or more, and particularly preferably 130 ° C. or more. When the glass transition point is at least the lower limit, cracking and the like of the solder in the thermal cycle test can be sufficiently suppressed.
Here, the glass transition point can be measured using a dynamic viscoelasticity measuring device (DMA). Specifically, using a dynamic viscoelasticity measuring apparatus “DMS 6100” manufactured by Seiko Instruments Inc., as a sample, a cured product (thickness: 100 μm, length: 20 mm, width: 4 mm) of a thermosetting flux composition is raised. The measurement can be performed under the condition of the temperature rate of 5 ° C./min, and the peak value of tan δ can be measured as the glass transition point. In addition, about the magnitude | size of a sample, if it is larger than the said conditions, it can measure.

The relative dielectric constant at 1 GHz of the cured product of the thermosetting flux composition of the present invention is preferably 3.0 or less, more preferably 2.7 or less, particularly preferably 2.5 or less preferable. The dielectric loss tangent at 1 GHz of the cured product of the thermosetting flux composition of the present invention is preferably 0.02 or less, more preferably 0.01 or less, and 0.005 or less. Particularly preferred. If the relative dielectric constant and the dielectric loss tangent are below the upper limits, it is possible to sufficiently suppress the occurrence of signal delay and noise.
Here, the relative dielectric constant and the dielectric loss tangent can be measured using an impedance analyzer. Specifically, using the impedance analyzer “4291 B” manufactured by HEWLETT PACKARD, the cured product of the thermosetting flux composition (thickness: 150 to 200 μm, length: 50 mm, width: 50 mm) is used as a sample at a measurement temperature of 25 ° C. The measurement can be performed under the condition of a frequency of 1 GHz to measure the dielectric constant and the dielectric loss tangent at a frequency of 1 GHz.

The viscosity of the thermosetting flux composition at 200 ° C. and 250 ° C., and the glass transition point of the cured product, the relative dielectric constant at 1 GHz, and the dielectric loss tangent may be adjusted to the above ranges by the following methods. Can be mentioned.
The viscosity at 200 ° C. and 250 ° C. of the thermosetting flux composition can be adjusted by changing the type of epoxy resin and curing agent (in particular, the type of curing agent). For example, the viscosity at 200 ° C. and 250 ° C. can be adjusted by adjusting the reactivity of the curing agent with the epoxy resin.
The glass transition point of the cured product can be adjusted by changing the kind and blending amount of the thermosetting resin and the curing agent. For example, the glass transition point can be adjusted by adjusting the combination of the thermosetting resin and the curing agent.
The relative dielectric constant and dielectric loss tangent at 1 GHz of the cured product can be adjusted by changing the kind and blending amount of the thermosetting resin and the curing agent. For example, the dielectric constant and the dielectric loss tangent can be adjusted by adjusting the combination of the thermosetting resin and the curing agent.

[(A) component]
The (A) thermosetting resin used in the present invention contains (A1) an epoxy resin and (A2) an active ester resin.
A well-known epoxy resin can be used suitably as said (A1) epoxy resin. Examples of such an epoxy resin include epoxy resins such as bisphenol A type, bisphenol F type, biphenyl type, naphthalene type, cresol novolac type, and phenol novolac type. These epoxy resins may be used alone or in combination of two or more. Moreover, it is preferable that these epoxy resins are rubber-modified from a viewpoint of the impact resistance of hardened | cured material. Furthermore, it is preferable that these epoxy resins contain a liquid thing at normal temperature, and when using a solid thing at normal temperature, it is preferable to use together with a liquid thing at normal temperature.

  Further, the component (A1) is one selected from the group consisting of bisphenol A epoxy resin and naphthalene type epoxy resin from the viewpoint of enhancing the glass transition temperature of the cured product and enhancing the impact resistance. Is preferred.

  The (A2) active ester resin is an ester resin that reacts with the (A1) epoxy resin, and is, for example, an ester resin represented by the following general formula (1).

In the general formula (1), R ¹ and R ² may be the same or different and each represents a substituted or unsubstituted hydrocarbon group.
As a commercial item of the said (A2) component, EPICLON HPC-8000-65T etc. (made by DIC) are mentioned.
Moreover, the reaction mechanism of the said (A1) component and the said (A2) component is as showing to the following reaction formula.

  The mass ratio (A1 / A2) of the component (A1) and the component (A2) is 1⁄2 or more and 4/1 or less from the viewpoint of the glass transition point of the cured product, the relative dielectric constant, and the dielectric loss tangent. Preferably, it is more preferably 1/1 or more and 2/1 or less.

  It is preferable that it is 40 to 95 mass% with respect to 100 mass% of thermosetting flux compositions, and, as for the compounding quantity of the said (A) component, it is more than 60 to 92 mass%. Preferably, 70% by mass or more and 90% by mass or less is particularly preferable. If the compounding quantity of (A) component is in the said range, sufficient hardenability can be ensured and the solder joint of an electronic component and an electronic substrate can fully be reinforced.

[(B) component]
The curing agent (B) used in the present invention is at least one selected from the group consisting of (B1) polyamine-based curing agents having a melting point of 150 ° C. or higher and (B2) imidazole-based curing agents, and (B3) pyridine-based Contains a curing agent. When these components (B1), (B2) and (B3) are used, the curing of the thermosetting flux composition can be prevented from progressing so much in the reflow step, and the heat curing after the reflow step In the process, the thermosetting flux composition can be sufficiently cured.
In addition, as the component (B), known epoxy resin curing agents other than the components (B1), (B2) and (B3) may be used as long as the effects of the present invention are not impaired. However, dicyandiamide (DICY) and its derivatives, or melamine and its derivatives, etc. are preferably not used because the curing of the thermosetting flux composition proceeds too much in the reflow step. When a known epoxy resin curing agent other than the (B1) component, the (B2) component and the (B3) component is used, the content thereof is 10% by mass or less based on 100% by mass of the (B) component. It is preferable that the content be 5% by mass or less.

As the component (B1), among those commercially available as polyamine-based epoxy curing agents, those having a melting point of 150 ° C. or more (more preferably 160 ° C. or more) can be selected and used.
As a commercial item of the said (B1) component, the modified | denatured aliphatic polyamine type hardening | curing agent of Adeka Hardener EH series etc. (made by ADEKA) etc. are mentioned.

Examples of the component (B2) include 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole and 2,4-diamino-6- [2′-ethyl-4 ′. -Methylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine, 2,4-diamino-6 -[2'-Methylimidazolyl- (1 ')]-ethyl-s-triazine isocyanuric acid adduct, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl- 2-undecylimidazole and 2,4-diamino-6- [2'-undecylimidazolyl- (1 ')]-ethyl-s-triazine It is below. Among these, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid adduct, and It is preferable to use 1-cyanoethyl-2-phenylimidazolium trimellitate or the like. One of these may be used alone, or two or more may be mixed and used.
Commercial products of the component (B2) include 2P4 MHZ, 2PHZ-PW, 2E4MZ-A, 2MZ-A, 2MA-OK, 2PZ-CN, 2PZCNS-PW, C11Z-CN, and C11Z-A Product names).

  Examples of the component (B3) include N, N-dimethyl-4-aminopyridine, N, N-diethyl-4-aminopyridine, 2-aminopyridine, 4-aminopyridine, and 2,6-diaminopyridine. Be Among these, it is preferable to use N, N-dimethyl-4-aminopyridine. One of these may be used alone, or two or more may be mixed and used.

In the present invention, in order to adjust the viscosity at 200 ° C. and 250 ° C. of the thermosetting flux composition, the glass transition point of the cured product, etc. to the above-mentioned range, the component (B1) and It is preferable to use it in combination of at least 1 sort (s) selected from the group which consists of B2 components, and (B3) components.
The mass ratio of the total amount of the component (B1) and the component (B2) to the component (B3) ((B1 + B2) / B3) is from the viewpoint of the glass transition point of the cured product, the relative dielectric constant and the dielectric loss tangent. And 2/1 or more and 30/1 or less, and more preferably 5/1 or more and 15/1 or less.

  The compounding amount of the component (B) is preferably 0.1% by mass to 10% by mass with respect to 100% by mass of the thermosetting flux composition, and 0.2% by mass to 5% by mass And more preferably 0.5% by mass or more and 3% by mass or less. If the compounding quantity of (B) component is more than the said minimum, the curability of a thermosetting flux composition is securable. On the other hand, if the compounding quantity of (B) component is below the said upper limit, the storage stability of a thermosetting flux composition is securable.

[(C) ingredient]
Examples of the (C) activator used in the present invention include organic acids, non-dissociating activators composed of non-dissociable halogenated compounds, and amine surfactants.

Examples of the organic acid include, in addition to monocarboxylic acids and dicarboxylic acids, other organic acids.
As monocarboxylic acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthate, capric acid, caprylic acid, lauric acid, myristic acid, pentadecyl acid, palmitic acid, margaric acid, stearic acid, tubercurostearic acid , Arachidic acid, behenic acid, lignoceric acid, glycolic acid and the like.
Examples of dicarboxylic acids 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.
Other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, picolinic acid and the like.

  Examples of the non-dissociating active agent include non-salt organic compounds in which a halogen atom is covalently bonded. The halogenated compound may be a compound having a single bond of chlorine, bromine or fluorine alone, such as chlorine, bromine or fluoride, but any two or all of chlorine, bromine and fluorine may be used. It may be a compound having a covalent bond of 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 compound, in order to improve the solubility in an aqueous solvent. As the halogenated alcohol, for example, 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 are mentioned. Examples of halogenated carboxyl compounds include 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, iodinated carboxyl compounds such as 5-iodoanthranilic acid, 2-chlorobenzoic acid, 3- Examples thereof include carboxyl chloride compounds such as chloropropionic acid, 2,3-dibromopropionic acid, brominated carboxyl compounds such as 2,3-dibromosuccinic acid and 2-bromobenzoic acid, and the like.

  Examples of the amine-based active agent include amines (polyamines such as ethylene diamine), amine salts (amines such as trimethylolamine, cyclohexylamine and diethylamine) and organic acid salts such as amino alcohol and inorganic acid salts (hydrochloric acid, sulfuric acid, odor Hydrochloric acid etc.), amino acids (glycine, alanine, aspartic acid, glutamic acid, valine etc.), amide compounds and the like. Specifically, diphenyl guanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine salt (hydrochloride, succinate, adipate, sebacate etc.), triethanolamine, monoethanolamine, etc. The hydrobromide of amine of

  The compounding amount of the component (C) is preferably 1% by mass or more and 25% by mass or less, and 2% by mass or more and 20% by mass or less based on 100% by mass of the thermosetting flux composition. More preferably, it is particularly preferably 3% by mass or more and 15% by mass or less. If the compounding quantity of (C) component is more than the said minimum, the defect of a solder joint can be prevented more reliably. Moreover, if the compounding quantity of (C) component is below the said upper limit, the insulation of a thermosetting flux composition is securable.

  The thermosetting flux composition of the present invention may further contain (D) a thixo agent in addition to the (A) component, the (B) component and the (C) component.

[(D) component]
Examples of the (D) thixotropic agent used in the present invention include hardened castor oil, amides, kaolin, colloidal silica, organic bentonite, glass frit and the like. One of these thixotropic agents may be used alone, or two or more thereof may be mixed and used.

  When using the said (D) component, it is preferable that the compounding quantity is 0.1 to 5 mass% with respect to 100 mass% of thermosetting flux compositions, and 0.5 to 2 mass%. It is more preferable that the content is at most mass%. If the compounding quantity of (D) component is more than the said minimum, sufficient thixotropy will be obtained and it can fully suppress dripping. Moreover, if the compounding quantity of (D) component is below the said upper limit, thixotropy will be too high and it will not become a printing defect.

[Other ingredients]
The thermosetting flux composition of the present invention may optionally contain, in addition to the components (A) to (D), a surfactant, a coupling agent, an antifoamer, a powder surface treatment agent, and a reaction suppression. You may contain additives, such as an agent, an anti-settling agent, and a filler. The blending amount of these additives is preferably 0.01% by mass to 10% by mass, and more preferably 0.05% by mass to 5% by mass, with respect to 100% by mass of the thermosetting flux composition. It is more preferable that

[Method of producing thermosetting flux composition]
The thermosetting flux composition of the present invention can be produced by blending the component (A) to the component (D) and the like at the predetermined ratio and stirring and mixing.

[Method of manufacturing electronic substrate]
Next, a method of manufacturing the electronic substrate of the present invention will be described. The method of using the thermosetting flux composition of the present invention is not limited to the method of producing an electronic substrate of the present invention.
The method for producing an electronic substrate according to the present invention is a method using the above-mentioned thermosetting flux composition according to the present invention, and comprises a coating step, a mounting step, a reflow step and a heat curing step described below.

In the application step, the thermosetting flux composition is applied onto the wiring substrate.
As a wiring board, a printed wiring board, a silicon substrate provided with wiring, etc. may be mentioned.
The coating devices include spin coaters, spray coaters, bar coaters, applicators, dispensers, and screen printers. In addition, when using a spin coater, a spray coater, etc. as a coating device, it is preferable to dilute and use a thermosetting flux composition with a solvent.
As the solvent, ketones (eg, methyl ethyl ketone, cyclohexanone), aromatic hydrocarbons (eg, toluene, xylene), alcohols (eg, methanol, isopropanol, cyclohexanol), alicyclic hydrocarbons (eg, cyclohexane) , Methyl cyclohexane), petroleum solvents (eg, petroleum ether, petroleum naphtha), cellosolves (eg, cellosolve, butyl cellosolve), (eg, carbitol, butyl carbitol), and esters (eg, ethyl acetate, Butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, ethyl diglycol acetate, diethylene glycol monomethyl ether acetate, diethylene glycol Roh ether acetate) and the like. One of these may be used alone, or two or more may be mixed and used.
The thickness of the coating film (coating film thickness) can be set appropriately.

In the mounting step, the electronic component having the solder bump is mounted on the bonding land of the wiring substrate.
As an electronic component which has a solder bump, a BGA package, a chip size package, etc. are mentioned, for example.
The solder bumps are preferably made of a solder alloy having a melting point of 200 ° C. or more and 230 ° C. or less. The solder bumps may be plated with a solder alloy on the surface thereof. As a solder alloy whose melting | fusing point is 200 degreeC or more and 230 degrees C or less, solder alloys, such as Sn-Ag-Cu type | system | group and Sn-Ag type | system | group, are mentioned.
As an apparatus used at a mounting process, a well-known chip mounting apparatus can be used suitably.
Further, as a material of the bonding land, a known conductive material (copper, silver or the like) can be appropriately used.

In the reflow process, the solder bump is melted by heating the wiring substrate on which the electronic component is mounted, and the solder bump is bonded to the bonding land.
As an apparatus used here, a well-known reflow furnace can be used suitably.
The reflow conditions may be appropriately set according to the melting point of the solder. For example, in the case of using a Sn-Au-Cu based solder alloy, preheating may be performed at a temperature of 150 to 180 ° C. for 60 to 120 seconds, and a peak temperature may be set to 220 to 260 ° C.

In the heat curing step, the thermosetting flux composition is heated and cured.
As heating conditions, the heating temperature is preferably 150 ° C. or more and 220 ° C. or less, and more preferably 180 ° C. or more and 200 ° C. or less. If the heating temperature is within the above range, the thermosetting flux composition can be sufficiently cured, and the adverse effect on the electronic component mounted on the electronic substrate is also small.
The heating time is preferably 10 minutes or more and 3 hours or less, and more preferably 30 minutes or more and 90 minutes or less. If the heating time is within the above range, the thermosetting flux composition can be sufficiently cured, and the adverse effect on the electronic component mounted on the electronic substrate is also small.

According to the method of manufacturing an electronic substrate as described above, the joint of the solder bump can be reinforced by the cured product of the thermosetting flux composition.
The method of manufacturing an electronic substrate according to the present invention is not limited to the above embodiment, and modifications, improvements and the like within the range in which the object of the present invention can be achieved are included in the present invention.

EXAMPLES The present invention will next be described in more detail by way of Examples and Comparative Examples, which should not be construed as limiting the invention thereto. In addition, the material used by the Example and the comparative example is shown below.
((A1) ingredient)
Epoxy resin A: bisphenol A type epoxy resin, trade name "EPICLON EXA-850 CRP", epoxy resin B manufactured by DIC: naphthalene type epoxy resin, trade name "EPICLON HP-4032D", manufactured by DIC (component (A2))
Active ester resin: trade name "EPICLON HPC-8000-65T", manufactured by DIC ((B2) component)
Curing agent A: 2-phenyl-4-methyl-5-hydroxymethylimidazole, trade name "2P4 MHZ", manufactured by Shikoku Kasei Kogyo Co., Ltd. ((B3) component)
Hardening agent B: N, N-dimethyl-4-aminopyridine ((C) component)
Activator A: Adipic Acid Activator B: Benzylamine Adipate (Component (D))
Thixotropic agent: trade name "Gerol D", manufactured by Shin Nippon Rika Co., Ltd. (other components)
Curing agent C: dicyandiamide curing agent D: melamine

Example 1
50 parts by mass of epoxy resin A, 37.9 parts by mass of epoxy resin B, 1 part by mass of curing agent A, 0.1 parts by mass of curing agent B, 5 parts by mass of activator A, 5 parts by mass of activator B and 1 part by mass of thixo agent The mixture was pulverized, mixed and dispersed in a pulverizing mixer to obtain a thermosetting flux composition.
Further, 10 parts by mass of a solvent (propylene glycol monomethyl ether acetate) was added to 100 parts by mass of the obtained thermosetting flux composition to prepare a spin coater application liquid.
Then, a spin coater coating solution was applied onto the substrate using a spin coater. The applied film thickness of the applied film was 30 μm. Next, a chip part (1005 chip, solder alloy: Sn-Au 3.0-Cu 0.5, melting point of solder: 217 ° C. to 220 ° C.) is mounted on the bonding land of the substrate after forming the coating, and reflow is performed The mixture was heated through a furnace (Tamura Seisakusho Co., Ltd.). The reflow conditions here are a preheating temperature of 150 to 180 ° C. (60 seconds), a time of 220 ° C. or more for 50 seconds, and a peak temperature of 230 ° C. Thereafter, the substrate after reflow was put into a heating furnace, and subjected to heat treatment at a temperature of 200 ° C. for 1 hour to produce a test substrate.

[Example 2, Comparative Examples 1 and 2]
A thermosetting flux composition, a coating solution for spin coater, and a test substrate were obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1.

<Evaluation of thermosetting flux composition>
Evaluation of thermosetting flux composition (viscosity of thermosetting flux composition at 200 ° C and 250 ° C, glass transition temperature of cured product, solderability, relative dielectric constant, dielectric loss tangent) was conducted by the following methods. The The obtained results are shown in Table 1.
(1) Viscosity of thermosetting flux composition Using a rheometer (manufactured by HAAKE, trade name "MARS-III"), the temperature is raised from a temperature of 25 ° C to the melting point of the solder at a heating rate of 5 ° C / min. While, the viscosity of the thermosetting flux composition was measured. From the obtained results, (i) viscosity at a temperature of 200 ° C. and (ii) viscosity at a temperature of 250 ° C. were determined. And about the viscosity, it divided according to the following standard.
A: The viscosity is 5 Pa · s or less.
B: The viscosity is more than 5 Pa · s and less than 50 Pa · s.
C: The viscosity is 50 Pa · s or more.
(2) Glass transition point of cured product A cured product of a thermosetting flux composition (curing conditions: 200 ° C. for 1 hour, thickness: 100 μm, length) using a dynamic viscoelasticity measuring apparatus “DMS 6100” manufactured by Seiko Instruments Inc. The measurement was performed under the conditions of a temperature rising rate of 5 ° C./min, using a sample of 20 mm in width and 4 mm in width. From the obtained graph, the peak value of tan δ was read as a glass transition point.
(3) Solder meltability Mix 50% by mass of thermosetting flux composition and 50% by mass of solder powder (solder alloy: Sn-Au 3.0-Cu 0.5, particle size distribution: 20 to 40 μm), A mixed sample was obtained. The obtained mixed sample was formed on a substrate (surface material: copper) by a screen printing method to form a coating having a diameter of 1 cm and a thickness of 50 μm, and was heated for 30 seconds on a hot plate set at a temperature of 250 ° C. Then, the molten state of the solder was visually observed, and the solder melting property was evaluated according to the following criteria.
○: The solder melted.
X: The solder did not melt.
(4) Relative dielectric constant and (5) Dielectric loss tangent A cured product of a thermosetting flux composition (coated film thickness: 200 μm, curing condition: 200 ° C. for 1 hour, thickness) using an impedance analyzer “4291 B” manufactured by HEWLETT PACKARD The measurement was performed under the conditions of a measurement temperature of 25 ° C. and a frequency of 1 GHz using a sample of 150 to 200 μm, a length of 50 mm, and a width of 50 mm, and the relative dielectric constant and the dielectric loss tangent at a frequency of 1 GHz were measured.

  As apparent from the results shown in Table 1, when the thermosetting flux composition of the present invention is used (Examples 1 and 2), the solderability is good and the glass transition point of the cured product is sufficient. It was confirmed that the dielectric constant and dielectric loss tangent of the cured product were sufficiently low. Moreover, it was confirmed that the solderability and the self-alignment property in reflow are excellent because of the solder melting property.

  The thermosetting flux composition of the present invention can be particularly suitably used as a technique for mounting an electronic component on an electronic substrate such as a printed wiring board of an electronic device.

Claims (3)

A thermosetting flux composition which does not contain conductive fine particles and is used when bonding an electronic component having a solder bump to an electronic substrate by reflow soldering, and
Applying the thermosetting flux composition on a wiring substrate;
A mounting step of mounting an electronic component having a solder bump made of a solder alloy having a melting point of 200 ° C. or more and 230 ° C. or less on the bonding land of the wiring substrate;
A reflow step of melting the solder bumps and bonding the solder bumps to the bonding lands by heating the wiring substrate on which the electronic component is mounted;
And a thermosetting step of heating and curing the thermosetting flux composition, wherein the thermosetting flux composition is used in a method of manufacturing an electronic substrate,
(A) containing a thermosetting resin, (B) a curing agent, and (C) an activator,
The component (A) contains (A1) an epoxy resin and (A2) an active ester resin,
The component (A1) is at least one selected from the group consisting of bisphenol A type epoxy resins and naphthalene type epoxy resins,
The component (B) contains at least one member selected from the group consisting of (B2) imidazole-based curing agents, and (B3) a pyridine-based curing agent,
The component (B2) is 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2,4-diamino-6- [2′-ethyl-4′- Methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-Methylimidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid adduct, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2 -Undecylimidazole, and 2,4-diamino-6- [2'-undecylimidazolyl- (1 ')]-ethyl-s-triazine It is at least one selected from,
The component (B3) is selected from the group consisting of N, N-dimethyl-4-aminopyridine, N, N-diethyl-4-aminopyridine, 2-aminopyridine, 4-aminopyridine, and 2,6-diaminopyridine At least one selected;
The component (C) contains an organic acid and an amine salt of the organic acid,
The organic acid is at least selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, and diglycolic acid One kind,
The mass ratio (A1 / A2) of the component (A1) to the component (A2) is 1/1 or more and 2/1 or less,
The compounding quantity of the said (A) component is 70 mass% or more with respect to 100 mass% of said thermosetting flux compositions,
A thermosetting flux composition, wherein a cured product of the thermosetting flux composition satisfies all of the following conditions (i) to (iii):
Condition (i): The glass transition point is 100 ° C. or more.
Condition (ii): The relative dielectric constant at 1 GHz is 2.5 or less.
Condition (iii): The dielectric loss tangent at 1 GHz is 0.005 or less. In the thermosetting flux composition according to claim 1,
When the temperature is raised at a temperature rising rate of 25 ° C. to 5 ° C./min, the viscosity at a temperature of 200 ° C. is 5 Pa · s or less, and the viscosity at a temperature of 250 ° C. is 50 Pa · s or more. Thermosetting flux composition. A method of manufacturing an electronic substrate using the thermosetting flux composition according to claim 1 or 2,
Applying the thermosetting flux composition on a wiring substrate;
A mounting step of mounting an electronic component having a solder bump made of a solder alloy having a melting point of 200 ° C. or more and 230 ° C. or less on the bonding land of the wiring substrate;
A reflow step of melting the solder bumps and bonding the solder bumps to the bonding lands by heating the wiring substrate on which the electronic component is mounted;
And a thermosetting process of heating and curing the thermosetting flux composition.