JP2010073872A - Solder connection method and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solder connection method superior in reliability with respect to a method for connecting solder via an adhesive layer having a flux function. <P>SOLUTION: This invention relates to the solder connection method for electrically connecting a first solder bump of a first electronic component having the first solder bump and an electrode of a second electronic component having the electrode via an adhesive layer having a flux function, the method including: a step of disposing the adhesive layer on the first electronic component so as to satisfy A>B wherein A[μm] is a height of the first solder bump from one surface of the first electronic component and B[μm] is a thickness of the adhesive layer having a flux function; and a contact step of not only heating and pressurizing the first solder bump to the electrode to deform the first solder bump so as to approximately equalize a distance between surfaces facing each other of the first electronic component and the second electronic component to the thickness [μm] of the adhesive layer but also bringing the first solder bump and the electrode into contact with each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solder connection method and an electronic device.

  In recent years, electronic devices such as semiconductor packages have been integrated with higher density and higher density in response to demands for higher functionality and lighter, thinner and smaller electronic devices. These electronic components have become smaller and more pins. It is out. In order to obtain an electrical connection between these electronic components, solder bonding is used. For example, a conductive bonding portion between semiconductor chips, a conductive bonding portion between a semiconductor chip and a circuit board such as a package on which a flip chip is mounted, It is used for a conductive junction between a circuit board and a circuit board. Furthermore, along with the demand for thinner and smaller electronic components and narrow pitch bonding, the solder joints are filled with underfill material using capillary action to reinforce the joints and ensure the reliability of the joints. .

When the gap generated by soldering is reinforced with a resin such as an underfill material, if the amount of the resin is larger than the volume of the space formed by the gap to be filled, the resin protrudes to an unnecessary place. In some cases, the terminal area for mounting other components may be limited by the resin that protrudes.
Furthermore, the underfill material using the capillary phenomenon takes a man-hour in the filling process of the underfill material, and causes a cost increase. Accordingly, a prescription has been proposed in which an underfill material mixed with a flux in advance is dropped when a semiconductor element is connected to a substrate, and then the underfill material is cured simultaneously with the solder connection (see, for example, Patent Document 1). This assembly method eliminates the filling process of the underfill material and is effective for significant cost reduction.

  However, underfill materials mixed with such flux (hereinafter referred to as non-flow underfill materials) are mainly liquid epoxy as the main agent and phthalic anhydride acid anhydride as the curing agent. This is because the acid anhydride itself of the curing agent has a flux action, and if necessary, the flux properties can be enhanced by adding an acid anhydride in excess of the equivalent of epoxy. However, acid anhydrides such as phthalic anhydride are highly hygroscopic, and are liable to increase in viscosity due to moisture absorption before and during use, causing problems in terms of reliability.

Japanese Patent Laid-Open No. 04-280443

An object of the present invention is to provide a solder connection method having excellent reliability in a method of connecting solder via an adhesive layer having a flux function.
Another object of the present invention is to provide an electronic device having excellent reliability.

Such an object is achieved by the present invention described in the following (1) to (8).
(1) Solder that electrically connects the first electronic bump having the first solder bump and the second electronic component having an electrode to the first solder bump and the electrode through an adhesive layer having a flux function. The height of the first solder bump from one surface of the first electronic component is A [μm], and the thickness of the adhesive layer having the flux function is B [μm]. A> B, and a step of arranging an adhesive layer having the flux function on the first electronic component;
The first solder bump is heated and pressed on the electrode so that the height A [μm] of the first solder bump is substantially the same as the thickness B [μm] of the adhesive layer having the flux function. And a contact step of deforming the first solder bump and bringing the first solder bump and the electrode into contact with each other.
(2) The solder connection method according to (1), wherein the electrode has a substantially flat surface.
(3) The solder connection method according to (1) or (2), wherein the electrode has a concave shape in a side view of the second electronic component by being covered with a coating layer.
(4) The solder connection method according to any one of (1) to (3), further including a curing step of curing the adhesive layer having the flux function.
(5) The adhesive layer having the flux function is composed of a resin composition containing a thermosetting resin and a compound having flux activity, and is described in any one of (1) to (4) above. Solder connection method.
(6) The solder connection method according to any one of (1) to (5), wherein in the contact step, the solder bump is melted and then heated so that the thermosetting resin is cured.
(7) When the adhesive having the flux function is heated from room temperature to a molten state at a heating rate of 10 ° C./min, the initial melt viscosity decreases, and after reaching the minimum melt viscosity, it further increases The solder connection method according to any one of (1) to (6) above, wherein the minimum melt viscosity is 10 to 10,000 Pa · s or less.
(8) An electronic apparatus having a solder connection portion connected by the solder connection method according to any one of (1) to (7).

ADVANTAGE OF THE INVENTION According to this invention, in the method of connecting solder via the adhesive bond layer which has a flux function, the solder connection method excellent in reliability can be provided.
Further, according to the present invention, it is possible to provide an electronic device with excellent reliability.

Hereinafter, a solder connection method and an electronic apparatus according to the present invention will be described in detail.
According to the solder connection method of the present invention, a first electronic component having a first solder bump and a second electronic component having an electrode are bonded to the first solder bump and the electrode via an adhesive layer having a flux function. A method of connecting solder for electrical connection, wherein the height of the first solder bump from one surface of the first electronic component is A [μm], and the thickness of the adhesive layer having the flux function is B [Μm] When A> B, the step of disposing the adhesive layer having the flux function on the first electronic component, and the distance between the opposing surfaces of the first electronic component and the second electronic component, The first solder bumps are deformed by heating and pressurizing the first solder bumps so as to be substantially the same as the thickness B [μm] of the adhesive layer having the flux function, and the first solder bumps are deformed. 1 Solder bumps are brought into contact with the electrodes Further, it characterized in that it comprises a step catalyst, the electronic apparatus of the present invention is characterized by having a solder connection connected by the solder connection method described above.

First, a solder connection method will be described based on a preferred embodiment shown in FIG.
FIG. 1 shows an example in which the electrodes of the second electronic component are substantially flat.
As shown in FIG. 1, a first substrate 1 is prepared as a first electronic component, and a second substrate 2 is prepared as a second electronic component (FIG. 1).
The first substrate 1 includes a core substrate 11, an electrode 12 provided on one surface side (lower side in FIG. 1) of the core substrate 11, and a first solder bump 13 provided so as to cover the electrode 12. The solder resist 14 covering one surface side of the core substrate 11, the circuit wiring 15 provided on the other surface side (upper side in FIG. 1) of the core substrate 11, the other of the circuit wiring 15 and the core substrate 11 It is comprised with the soldering resist 14 provided so that the surface side might be covered.

  The second substrate 2 covers the core substrate 21, the electrode 22 provided on one surface side (the upper side in FIG. 1) of the core substrate 21, the periphery of the electrode 22, and the one surface side of the core substrate 21. Solder resist 24, circuit wiring 25 provided on the other surface side (lower side in FIG. 1) of core substrate 21, and solder provided so as to cover circuit wiring 25 and the other surface side of core substrate 21 And a resist 24. A metal layer 23 is formed on the surface of the electrode 22. The periphery of the electrode 22 is covered with a solder resist 24, and the solder resist 24 and the metal layer 23 are substantially flush with each other (substantially flat).

  Examples of materials that can be used for the metal layer 23 include solder, copper, gold, silver, aluminum, nickel, and the like, preferably copper and nickel that form an intermetallic compound with the first solder bump 13, and more preferably, The first solder bump 13 and the metal layer 23 are melted and integrated with solder and gold. Furthermore, the above-mentioned materials can be used by forming not only one type but also a plurality. For example, after nickel is formed on the concave electrode 22 by electroless plating and gold is further formed by electroless plating, the solder is formed by printing so that the solder resist 24 and the metal layer 23 are substantially on the same surface, so that there is no unevenness. Form. Thereby, wettability with the 1st solder bump 13 improves, and a solder connection part with higher connection reliability can be formed.

(Arrangement of adhesive layer with flux function)
In the arrangement of the adhesive layer 3 having the flux function, the adhesive layer 3 having the flux function is laminated on the side of the first substrate 1 where the first solder bumps 13 are provided.
Next, the adhesive layer 3 having a flux function is laminated on the side of the first substrate 1 where the first solder bumps 13 are provided, and the adhesive layer 3 having a flux function is disposed (FIG. 2). At this time, the height A [μm] of the first solder bump 13 is set from one surface of the first substrate 1 (the lower surface 141 of the solder resist 14 below the first substrate 1 in FIG. 2), and the flux function. When the thickness of the adhesive layer 3 having B is B [μm], A> B.
Accordingly, the first solder bump 13 is brought into contact with the metal layer 23 by heating and pressure bonding, and is crushed while removing the adhesive layer 3 interposed between the first solder bump 13 and the metal layer 23. The tip 131 of the first solder bump 13 is more easily exposed than the adhesive layer 3 having a flux function. Thereby, it is possible to prevent the adhesive layer 3 having a flux function from being sandwiched between the first solder bump 13 and the metal layer 23 (resin biting) at the time of solder connection.

  More specifically, the height A [μm] of the solder bump 13 from one surface of the first substrate 1 (the lower surface 141 of the solder resist 14 below the first substrate 1) and an adhesive having a flux function The thickness B [μm] of the layer 3 is preferably 10 ≦ A−B ≦ 100, and preferably 20 ≦ A−B ≦ 35. When A and B are within the above ranges, resin biting can be reduced, and the amount of resin protruding due to pressurization can be reduced.

  Specifically, the height A [μm] of the first solder bump 13 from one surface of the first substrate 1 is not particularly limited, but is preferably 5 to 400 μm, and particularly preferably 50 to 65 μm. preferable. If the difference in height is within the above range, a large number of connection terminals are formed in the component, and even if the height variation during solder formation increases to some extent, the solder bumps are pressed to the thickness of the adhesive layer. Since it becomes easy to mutually contact, the yield which obtains a favorable solder connection part can be raised.

  Further, the thickness B [μm] of the adhesive layer 3 having a flux function is not particularly limited, but is preferably 10 to 390 μm, and particularly preferably 30 to 35 μm. When the thicknesses of A and B are within a range that satisfies the above-described relationship, the connection reliability and the effect of reducing the occurrence of voids in the adhesive layer are excellent.

The adhesive layer 3 having the flux function is composed of, for example, a thermosetting resin and a resin composition containing a compound having flux activity.
Examples of the thermosetting resin include epoxy resin, oxetane resin, phenol resin, (meth) acrylate resin, unsaturated polyester resin, diallyl phthalate resin, and maleimide resin. Among them, an epoxy resin excellent in curability and storage stability, heat resistance, moisture resistance, and chemical resistance of a cured product is preferably used.

  The epoxy resin may be either an epoxy resin that is solid at room temperature or an epoxy resin that is liquid at room temperature. Further, an epoxy resin that is solid at room temperature and an epoxy resin that is liquid at room temperature may be used in combination. Thereby, the design freedom of the melting behavior of the resin can be further increased.

  The epoxy resin solid at room temperature is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidylamine type epoxy resin, glycidyl Examples include ester type epoxy resins, trifunctional epoxy resins, and tetrafunctional epoxy resins. More specifically, a solid trifunctional epoxy resin and a cresol novolac type epoxy resin may be included.

  The epoxy resin that is liquid at room temperature may be a bisphenol A type epoxy resin or a bisphenol F type epoxy resin. Moreover, you may use combining these.

  Although content of the said thermosetting resin is not specifically limited, 25 to 75 weight% of the whole said resin composition is preferable, and 45 to 70 weight% is especially preferable. When the content is within the above range, good curability can be obtained, and good melting behavior can be designed.

The compound having the flux activity has a function of reducing the oxide film on the surface of the electrode terminal such as a solder bump that hinders the connection and has a reducing power to remove the oxide film.
The compound having the flux activity is, for example, a compound having at least one carboxyl group and / or phenolic hydroxyl group in the molecule, and may be liquid or solid.

  Examples of the flux active compound containing a carboxyl group include aliphatic acid anhydrides, alicyclic acid anhydrides, aromatic acid anhydrides, aliphatic carboxylic acids, and aromatic carboxylic acids. Examples of the flux active compound having a phenolic hydroxyl group include phenols.

  Examples of the aliphatic acid anhydride include succinic anhydride, polyadipic acid anhydride, polyazeline acid anhydride and polysebacic acid anhydride.

  Examples of the alicyclic acid anhydride include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhymic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexene dicarboxylic acid. An acid anhydride etc. are mentioned.

  Examples of the aromatic acid anhydride include phthalic anhydride trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tris trimellitate, and the like.

  As said aliphatic carboxylic acid, the compound shown by following formula (1) is mentioned.

Moreover, from the balance of flux activity, the outgas at the time of adhesion | attachment, the elasticity modulus after hardening of an adhesive agent, and glass transition temperature, n in said Formula (1) has preferable 3-10. By setting n to 3 or more, it is possible to suppress an increase in the elastic modulus after curing of the adhesive and to improve the adhesion to the adherend. Further, by setting n to 10 or less, it is possible to suppress a decrease in elastic modulus and further improve connection reliability.
As the compound represented by the above formula (1), for example, n = 3 glutaric acid (HOOC— (CH ₂ ) ₃ —COOH), n = 4 adipic acid (HOOC— (CH ₂ ) ₄ —COOH), n = 5 pimelic acid (HOOC— (CH ₂ ) ₅ —COOH), n = 8 sebacic acid (HOOC— (CH ₂ ) ₈ —COOH) and n = ₁₀ HOOC— (CH ₂ ) ₁₀ —COOH—. It is done.
Other aliphatic carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid pivalate, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, acrylic acid, methacrylic acid, crotonic acid, Examples include oleic acid, fumaric acid, maleic acid, oxalic acid, malonic acid, and oxalic acid.

  Examples of the aromatic carboxylic acid include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, hemimellitic acid, trimellitic acid, trimesic acid, merophanic acid, platnic acid, pyromellitic acid, merit acid, triyl acid, and xylyl acid. , Hemelitic acid, mesitylene acid, prenylic acid, toluic acid, cinnamic acid, salicylic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, gentisic acid (2,5-dihydroxybenzoic acid), 2,6 -Dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, gallic acid (3,4,5-trihydroxybenzoic acid), 1,4-dihydroxy-2-naphthoic acid, 3,5-dihydroxy-2-naphthoic acid Naphthoic acid derivatives such as phenolphthalin; diphenolic acid and the like.

  Examples of the flux active compound having a phenolic hydroxyl group include phenol, o-cresol, 2,6-xylenol, p-cresol, m-cresol, o-ethylphenol, 2,4-xylenol, 2,5 xylenol, m. -Ethylphenol, 2,3-xylenol, meditol, 3,5-xylenol, p-tertiarybutylphenol, catechol, p-tertiaryamylphenol, resorcinol, p-octylphenol, p-phenylphenol, bisphenol A, bisphenol F, Monomers containing phenolic hydroxyl groups such as bisphenol AF, biphenol, diallyl bisphenol F, diallyl bisphenol A, trisphenol, tetrakisphenol, phenol novolac resin, o-c Tetrazole novolac resin, bisphenol F novolac resin, bisphenol A novolac resins.

Since the flux active compound is three-dimensionally incorporated by reaction with a thermosetting resin such as an epoxy resin, at least two phenolic hydroxyl groups that can be added to the epoxy resin in one molecule, and metal oxidation A compound having at least one carboxyl group directly bonded to an aromatic group exhibiting a flux action on the membrane is preferable. Examples of such compounds include 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, gentisic acid (2,5-dihydroxybenzoic acid), 2,6-dihydroxybenzoic acid, and 3,4-dihydroxybenzoic acid. Benzoic acid derivatives such as acid and gallic acid (3,4,5-trihydroxybenzoic acid); 1,4-dihydroxy-2-naphthoic acid, 3,5-dihydroxy-2-naphthoic acid, 3,7-dihydroxy- Naphthoic acid derivatives such as 2-naphthoic acid; phenolphthaline; and diphenolic acid.
These flux active compounds may be used alone or in combination of two or more.

  The content of the compound having the flux activity is not particularly limited. However, from the viewpoint of improving the flux activity, the content is preferably 1% by weight or more, particularly preferably 5% by weight or more of the entire resin composition. . If the thermosetting resin and the unreacted flux active compound remain, it causes migration. Therefore, in order to prevent a flux active compound that does not react with the thermosetting resin from remaining, the content of the flux active compound is not particularly limited, but is preferably 30% by weight or less of the entire resin composition. In particular, it is preferably 25% by weight or less. Within the above range, the oxide film on the surface of the copper foil is reduced, and a good bond with high strength can be obtained.

Although the said resin composition is not specifically limited, It is preferable that the hardening | curing agent of the said thermosetting resin is included.
Examples of the curing agent include phenols, amines, and thiols. When an epoxy resin is used as the thermosetting resin, good reactivity with the epoxy resin, low dimensional change during curing, and appropriate physical properties after curing (for example, heat resistance, moisture resistance, etc.) are obtained. Phenols are preferably used.

  Although it does not specifically limit as said phenols, When the physical property after hardening of an adhesive agent is considered, bifunctional or more is preferable. Examples include bisphenol A, tetramethylbisphenol A, diallyl bisphenol A, biphenol, bisphenol F, diallyl bisphenol F, trisphenol, tetrakisphenol, phenol novolacs, cresol novolacs, etc., but melt viscosity, reactivity with epoxy resin When considering the physical properties after curing, phenol novolacs and cresol novolacs can be preferably used.

  When phenol novolacs are used as the curing agent, the content thereof is not particularly limited. However, from the viewpoint of reliably curing the resin, it is preferably 5% by weight or more, particularly 10% by weight based on the total resin composition. The above is preferable. If epoxy resin and unreacted phenol novolac remain, it causes migration. Therefore, in order not to remain as a residue, it is preferably 30% by weight or less, and particularly preferably 25% by weight or less, based on the entire resin composition.

  When the thermosetting resin is an epoxy resin, the content of the phenol novolac resin may be defined by an equivalent ratio with respect to the epoxy resin. Specifically, the equivalent ratio of the phenol novolac to the epoxy resin is not particularly limited, but is preferably 0.5 or more and 1.2 or less, particularly preferably 0.6 or more and 1.1 or less, and most preferably 0.7 Above, 0.98 or less is preferable. By setting the equivalent ratio of the phenol novolac resin to the epoxy resin to be equal to or higher than the lower limit, heat resistance and moisture resistance after curing can be ensured, and by setting the equivalent ratio to be equal to or lower than the upper limit, The amount of the epoxy resin and the unreacted residual phenol novolac resin can be reduced, and the migration resistance is improved.

  As another curing agent, for example, an imidazole compound having a melting point of 150 ° C. or higher can be used. If the melting point of the imidazole compound is too low, the adhesive resin may harden before the solder powder moves to the electrode surface, which may result in unstable connection or decrease the storage stability of the adhesive. . Therefore, the melting point of imidazole is preferably 150 ° C. or higher. Examples of the imidazole compound having a melting point of 150 ° C. or higher include 2-phenylhydroxyimidazole and 2-phenyl-4-methylhydroxyimidazole. In addition, there is no restriction | limiting in particular in the upper limit of melting | fusing point of an imidazole compound, According to the adhesion temperature of an adhesive agent, it can set suitably.

When an imidazole compound is used as the curing agent, the content thereof is not particularly limited, but is preferably 0.005% by weight or more and 10% by weight or less, particularly 0.01% by weight of the entire resin composition. The content is preferably 5% by weight or less.
By making content of the said imidazole compound more than the said lower limit, the function as a curing catalyst of a thermosetting resin can be exhibited more effectively, and the sclerosis | hardenability of an adhesive agent can be improved. Further, by setting the content of the imidazole compound to the upper limit value or less, the melt viscosity of the resin is not too high at the temperature at which the solder melts, and a good solder joint structure is obtained. Moreover, the preservability of the adhesive can be further improved.
These curing agents may be used alone or in combination of two or more.

Although the said resin composition is not specifically limited, It is preferable that film forming resin is included. Thereby, the film forming property to a film can be improved.
Examples of the film-forming resin include phenoxy resin, polyester resin, polyurethane resin, polyimide resin, siloxane-modified polyimide resin, polybutadiene, polypropylene, styrene-butadiene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer, Polyacetal resin, polyvinyl butyral resin, polyvinyl acetal resin, butyl rubber, chloroprene rubber, polyamide resin, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-acrylic acid copolymer, acrylonitrile-butadiene-styrene copolymer, polyvinyl acetate, nylon Acrylic rubber or the like can be used. These may be used alone or in combination of two or more.

  When a phenoxy resin is used as the film-forming resin, its number average molecular weight is not particularly limited, but a phenoxy resin having a molecular weight of 5,000 to 15,000 is preferable. By using such a phenoxy resin, the fluidity of the adhesive before curing can be suppressed and the interlayer thickness can be made uniform. Examples of the skeleton of the phenoxy resin include, but are not limited to, bisphenol A type, bisphenol F type, and biphenyl skeleton type. Preferably, a phenoxy resin having a saturated water absorption rate of 1% or less is preferable because foaming, peeling, and the like can be suppressed even at high temperatures during bonding and solder mounting.

In addition, as the film-forming resin, a resin having a functional group such as a nitrile group, an epoxy group, a hydroxyl group, or a carboxyl group may be used for the purpose of improving adhesiveness or compatibility with other resins. As such a resin, for example, an acrylic rubber having a functional group can be used.
When acrylic rubber (having a functional group) is used as the film-forming resin, it is possible to improve film formation stability when producing a film-like adhesive. In addition, since the elastic modulus of the adhesive can be reduced and the residual stress between the adherend and the adhesive can be reduced, the adhesion to the adherend can be improved.

  The content of the film-forming resin is not particularly limited, but is preferably 5% by weight or more and 45% by weight or less of the entire resin composition. When the film-forming resin is blended within the above range, a decrease in film formability is suppressed and an increase in the elastic modulus after curing of the adhesive is suppressed. Can be improved. Moreover, the increase in the melt viscosity of an adhesive agent is suppressed by setting it as the said range.

  Moreover, although the said resin composition is not specifically limited, It is preferable that a silane coupling agent is included. Thereby, the adhesiveness to the to-be-adhered thing of an adhesive agent can further be improved. Examples of the silane coupling agent include epoxy silane coupling agents and aromatic-containing aminosilane coupling agents. These may be used alone or in combination of two or more.

  Although content of a silane coupling agent is not specifically limited, 0.01 to 5 weight% of the whole said resin composition is preferable, and 0.1 to 1 weight% is especially preferable. When the content is within the above range, the effect of improving the adhesion is particularly excellent.

  The resin composition may contain components other than those described above. For example, various additives may be appropriately added in order to improve various properties such as resin compatibility, stability, and workability. May be included.

Such a resin composition is dissolved in an aromatic hydrocarbon solvent such as toluene or xylene, an ester organic solvent such as ethyl acetate or butyl acetate, or a ketone organic solvent such as acetone or methyl ethyl ketone, and the resulting varnish is polyester. The adhesive layer 3 formed on the polyester sheet is obtained by applying to a sheet and drying at a temperature at which the solvent evaporates to produce an adhesive sheet.
Next, the adhesive layer 3 having a flux function is laminated on the side of the first substrate 1 on which the first solder bumps 13 are provided, and the polyester sheet is peeled off to thereby form the adhesive layer 3 having a flux function. Obtainable.

(Contact process between first solder bump and electrode)
In this contact step, the first solder bumps 13 are heated and pressurized to be deformed so that the height of the first solder bumps 13 is the same as the thickness of the adhesive layer 3 having a flux function.
Next, the first substrate 1 and the second substrate 2 are formed so that the height A [μm] of the first solder bump 13 is substantially the same as the thickness B [μm] of the adhesive layer 3 having a flux function. At least one of them is heated and pressurized to deform the first solder bump 13 metal layer 23 and to bring the first solder bump 13 and the metal layer 23 into contact with each other (FIG. 3).
Here, the height A [μm] of the first solder bumps 13 and the thickness B [μm] of the adhesive layer 3 having a flux function initially had a relationship of A> B. The first solder bump 13 and the metal layer 23 are deformed by heating and pressurizing as described above, whereby the height A [μm] of the first solder bump 13 is set to the thickness B of the adhesive layer 3 having a flux function. μm] to be substantially the same. Thereby, it is possible to prevent a phenomenon (resin biting) in which the adhesive layer 3 having a flux function is sandwiched between the first solder bumps 13 and the metal layer 23 and remains.
The reason why this resin biting can be prevented is that, as described above, the first solder bump 13 is deformed so as to exclude the adhesive layer 3 having a flux function that covers the tip of the first solder bump 13.

The heating and pressurizing to deform the height of the first solder bump 13 so as to be substantially the same as the thickness of the adhesive layer 3 having a flux function is a resin composition constituting the adhesive layer 3 having a flux function. The thermosetting resin in the product is preferably carried out under conditions that do not initiate the curing reaction. This facilitates removal of the adhesive layer 3 having a flux function that covers the tip of the first solder bump 13.
Specifically, the heating conditions are not particularly limited, but are preferably 80 to 150 ° C. × 5 seconds to 5 minutes, and particularly preferably 90 to 120 ° C. × 30 seconds to 2 minutes. Moreover, although pressurization conditions are not specifically limited, 0.4-1.0 [MPa] is preferable and 0.6-0.9 [MPa] is especially preferable. When the heating / pressurizing condition is within the above range, the effect of reducing the generation of voids due to poor filling of the adhesive layer 3 having a flux function that occurs particularly in the vicinity of the first solder bump is excellent. Furthermore, it is excellent in the effect of removing the adhesive layer 3 having a flux function from between the first solder bumps 13 and the metal layer 23, and the first solder bumps 13 and the metal layer 23 are resin-engaged in a solder bonding step to be described later. It becomes easy to join without doing.

(Solder connection process)
In the solder connection step, the solder of the first solder bump 13 is melted and connected to the metal layer 23.
Next, a solder connection step of connecting the first solder bump 13 and the metal layer 23 by melting the solder is provided. As a result, the first solder bump 13 and the metal layer 23 are solder-connected (FIG. 4).
Specifically, although depending on the type of solder, for example, in the case of Sn-Ag, it is preferable to perform solder connection by heating at 220 to 260 ° C. for 30 to 120 seconds, particularly 230 to 240 ° C. for 60 to 100 seconds. It is preferable to do.
Further, this heating is preferably performed so that the thermosetting resin constituting the adhesive layer 3 is cured after the first solder bump 13 and the metal layer 23 are melted. That is, it is preferable that the solder of the solder bump is melted before the thermosetting resin constituting the adhesive layer 3 by heating is cured. This is because if the thermosetting resin is cured before the solder is melted, the shape of the solder connection portion is fixed by the curing of the thermosetting resin, and a suitable shape may not be obtained.
On the other hand, when the first solder bump 13 and the metal layer 23 are melted as described above and then heated so that the thermosetting resin constituting the adhesive layer 3 is cured, the first solder bump 13 and the metal layer When the layer 23 is pressure-bonded and deformed, the solder melts not only at the front end portion of the solder bump but also at the peripheral portion (end portion), so that a stable connection portion shape can be obtained.

  When the temperature of the adhesive 3 having a flux function is increased from room temperature to a molten state at a temperature increase rate of 10 ° C./min, the initial melt viscosity decreases, and after reaching the minimum melt viscosity, the characteristics are such that it further increases. The minimum melt viscosity when it is contained is not particularly limited, but is preferably 10 to 100,000 Pa · s, more preferably 100 to 5,000 Pa · s, and particularly preferably 1,000 to 2,000 Pa · s. When the minimum melt viscosity of the adhesive layer 3 having a flux function is within the above range, particularly, the reduction of voids generated in the adhesive layer during heat treatment due to moisture absorption of the electronic component and gas components generated from the electronic component itself, and The effect of eliminating the adhesive layer between the first solder bump 13 and the metal layer 23 is excellent. When the minimum melt viscosity is less than the lower limit value, the solder bumps may be scattered in the resin other than between the terminals due to the flow of the resin. If the upper limit is exceeded, the first solder bump 13 and the metal layer 23 may not be integrated, and the shape of the solder bump being pressed may be maintained.

Next, it has the hardening process which heats and hardens the adhesive bond layer 3 which has a flux function. Thereby, the adhesive layer 3 can ensure appropriate physical properties (for example, heat resistance, moisture resistance, etc.).
Although the said hardening process will not be specifically limited if the thermosetting resin which comprises the adhesive bond layer 3 which has a flux function hardens | cures, specifically 160-200 degreeC is preferable, and 170-190 degreeC is especially preferable. .

  By the method as described above, the solder connection portion 5 can be formed by bonding the first solder bump 13 of the first substrate 1 and the metal layer 23 of the second substrate 2 via the adhesive layer 3 having a flux function. . By using such a method, the solder joint has been filled with an underfill material that utilizes capillary action to reinforce the joint, and the joint has been formed. Since the formation of the solder and the reinforcement of the solder joint portion with the resin can be performed at the same time, the process can be greatly shortened. Furthermore, it is possible to stack the insulating layers of the multilayer substrate formed for each layer in a lump and form the conductors in a lump.

  Next, a solder connection method will be described in which the electrode 42 and the metal layer 43 of the second electronic component (second substrate 4) are concave in the side view due to the solder resist 44.

FIG. 5 shows an example in which the metal layer 43 is covered with the solder resist 44 so that the metal layer 43 is concave in a side view of the second electronic component 4. The depth C of the metal layer 43 from the surface 441 of the second substrate 4 is C [μm].
At this time, the height A [μm] of the first solder bump 13, the depth C [μm] of the metal layer 43 from the surface of the second substrate 4, and the thickness of the adhesive layer 3 having a flux function are set to B [ μm] is A−C> B.
Accordingly, in the same manner as in the case where the side surface of the metal layer 23 of the second substrate 2 is flat, the first solder bump 13 is brought into contact with the metal layer 43 by heating and pressure bonding, and the first solder bump 13 and By crushing while removing the adhesive layer 3 interposed between the metal layer 43 and the adhesive layer 3 having a flux function, the tip 131 of the first solder bump 13 is more easily exposed. Thereby, it is possible to prevent the adhesive layer 3 having a flux function from being sandwiched between the first solder bump 13 and the metal layer 43 (resin biting) at the time of solder connection.

More specifically, the height A [μm] of the solder bump 13 from one surface of the first substrate 1 (the lower surface 141 of the solder resist 14 below the first substrate 1) and an adhesive having a flux function The thickness B [μm] of the layer 3 is preferably 10 ≦ ABC ≦ 100, and preferably 20 ≦ ABC ≦ 35.
When A, B, and C are within the above ranges, resin biting can be reduced, the amount of resin protruding due to pressurization is reduced, and the expansion of the solder bump width due to deformation of the solder bumps is suppressed. be able to.

  Specifically, a bump obtained by subtracting the depth C [μm] of the metal layer 43 from the surface of the second substrate 4 from the height A [μm] of the first solder bump 13 from one surface of the first substrate 1. Although the value of height is not specifically limited, It is preferable that it is 5-400 micrometers, and it is especially preferable that it is 50-65 micrometers. When the height value is within the above range, a large number of connection terminals are formed in the component, and even if the height variation during solder formation becomes large to some extent, the solder bumps are pressed to the thickness of the adhesive layer. Since it becomes easy to mutually contact, the yield which obtains a favorable solder connection part can be raised. At this time, the depth C [μm] of the metal layer 43 is preferably 50 μm or less, and particularly preferably 5 to 15 μm.

  Further, the thickness B [μm] of the adhesive layer 3 having a flux function is not particularly limited, but is preferably 10 to 390 μm, and particularly preferably 30 to 35 μm. If the thicknesses of A, B, and C satisfy the above-described relationship, the balance between connection reliability and the effect of reducing the occurrence of voids in the adhesive layer is excellent.

  The following steps can be performed in the same manner as in the case where the above-described solder resist and the metal layer are substantially flush and have no irregularities.

Examples of the electronic component of the present invention include an organic substrate having solder bumps, a ceramic substrate having solder bumps, and a semiconductor element having solder bumps.
The electronic apparatus of the present invention includes, for example, a semiconductor device in which the electronic components as described above are electrically connected.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to this.

(Examples 1-6 and Comparative Examples 1-2)
(Manufacture of adhesive tape)
Each component shown in Table 1 was dissolved in methyl ethyl ketone to obtain a resin varnish. This resin varnish was applied to a polyester sheet, dried at 80 ° C. for 3 minutes, and then dried at 120 ° C. for 3 minutes to obtain an adhesive layer (adhesive tape) having a thickness of 30 μm and having a flux function. In addition, the compounding quantity in a table | surface is the weight% with respect to the total amount of a compounding component.

(Manufacture of electronic components)
Production of the first substrate (first electronic component having the first solder bump) and the second substrate (second electronic component in which the electrode 42 and the metal layer 43 of the second electronic component are concave in a side view) 12 μm After etching the double-sided copper-clad laminate with copper foil (ELC-4785GS manufactured by Sumitomo Bakelite Co., Ltd.) to form a copper circuit pattern, the copper circuit pattern is roughened and solder resist (PSR manufactured by Taiyo Ink Manufacturing Co., Ltd.) -AUS703) is printed on both surfaces with a thickness of 15 μm on a copper circuit, exposed and developed to form a 200 μm opening, and then an electroless nickel layer is formed on the copper circuit pattern in the opening with a thickness of 3 μm. An electrolytic gold plating layer was formed with a thickness of 0.03 μm to obtain a second substrate. Furthermore, a solder (Sn / 3.5Ag) paste is printed and formed to a desired height, and the solder paste is melted by reflow to obtain the desired height from the solder resist (substrate with solder bumps). Got.

-Fabrication of multilayer circuit board (electronic component) On the surface of the first board on which the solder bumps are formed, a 30 μm thick adhesive layer with a flux function is vacuum pressed (MVLP-500 manufactured by Meiki Seisakusho) at 120 ° C. The polyester film was peeled off at 0.8 MPa for 30 seconds. Next, it aligned so that the solder bump and concave electrode of the 1st board | substrate and the 2nd board | substrate might oppose, and it shape | molded by 120 degreeC and 0.8 Mpa for 30 second by the vacuum press.
Subsequently, it pressed at 240 degreeC and 0.3 Mpa for 120 second with the flat plate press (MSA-2 by system development), and solder bumps were joined. Furthermore, in order to cure the thermosetting flux tape, a heat history was applied at 180 ° C. for 60 minutes to obtain a multilayer circuit board (electronic component).

The following evaluation was performed about the adhesive layer with a flux function (adhesive film with a flux function) and electronic component which were obtained by each Example and the comparative example. The evaluation items are shown together with the contents. The obtained results are shown in Table 1.
1. Measurement of melt viscosity The melt viscosity was measured using the obtained adhesive layer with a flux function (adhesive tape). Specifically, an adhesive tape having a thickness of 100 μm is measured with a viscoelasticity measuring device (manufactured by Jusco International) at a temperature rising rate of 10 ° C./min, a frequency of 1.0 Hz, and constant strain-stress detection. When measured up to 300 ° C., the melt viscosity initially decreased, and after reaching the minimum melt viscosity, the minimum melt viscosity when further increased was examined.
In addition, about the adhesive tape of Example 2, it heat-processed for 60 minutes at 100 degreeC. As a result, the resin was partially cured to adjust the minimum melt viscosity.

2. Connection Ratio The interlayer connection resistance of the obtained multilayer circuit board (electronic component) was measured at 20 bump connection portions with a digital multimeter. The measurement was performed both after the production of the multilayer circuit board and after 1,000 cycles of a temperature cycle of -65 ° C for 1 hour and 150 ° C for 1 hour. Evaluation was performed at n = 20. Each code is as follows.
A: There were 20 multilayer circuit boards in which conduction was obtained at all bump connection portions.
A: There were 18 or 19 multilayer circuit boards in which conduction was obtained at all bump connection portions.
(Triangle | delta): The multilayer circuit board from which conduction | electrical_connection was able to be taken in all the bump connection parts was 16 pieces or 17 pieces.
X: There were 15 or less multilayer circuit boards in which conduction was obtained at all bump connection portions.

3. Evaluation of junction cross section The obtained multilayer circuit board was embedded in an epoxy resin cured product, the cross section was polished, and 10 interlayer connection portions were observed with an SEM (scanning electron microscope). Each code is as follows.
○: The connection shape was stable at all 10 locations.
X: Solder bumps and concave electrodes were not integrated, or there were one or more bumps in which solder flowed into the resin.

4). Measurement of spreading amount of adhesive layer by pressurization When making a multilayer circuit board, observe the images by the transmission method with an ultrasonic flaw detector before and after crimping with a flat plate press, and increase the area of the spreading of the adhesive layer. Measured by rate. Each code is as follows.
A: The spread amount of the resin was within 5.0%.
○: The spread amount of the resin exceeded 5.0% and was within 10.0%.
(Triangle | delta): The spreading amount of resin exceeded 10.0% and was within 50.0%.
X: The spread amount of the resin exceeded 50%.

As is clear from Table 1, Examples 1 to 6 were excellent in connectivity.
In addition, in Examples 1 to 6, it was suggested that the cross-sectional shape of the joint portion of the solder was stable and excellent in reliability.
In Examples 1 and 3 to 6, it was shown that the amount of spread of the resin is small and the contamination of electronic parts and the like is reduced.

FIG. 1 is a cross-sectional view illustrating a solder connection method according to the present invention. FIG. 2 is a cross-sectional view illustrating the solder connection method of the present invention. FIG. 3 is a cross-sectional view illustrating the solder connection method of the present invention. FIG. 4 is a cross-sectional view illustrating the solder connection method of the present invention. FIG. 5 is a cross-sectional view illustrating the solder connection method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st board | substrate 11 Core board | substrate 12 Terminal 13 1st solder bump 131 Tip part 14 Solder resist 141 Lower surface 15 Circuit wiring 2 2nd board | substrate 21 Core board 22 Terminal 23 Flat or concave shaped electrode 24 Solder resist 241 Upper surface 25 Circuit wiring 3 Adhesive layer having flux function 4 Second substrate 41 Core substrate 42 Terminal 43 Flat or concave electrode 44 Solder resist 441 Upper surface 45 Circuit wiring 5 Solder connection portion

Claims (8)

A solder connection method for electrically connecting a first electronic component having a first solder bump and a second electronic component having an electrode to each other through the adhesive layer having a flux function. Because
When the height of the first solder bump from one surface of the first electronic component is A [μm] and the thickness of the adhesive layer having the flux function is B [μm], A> B,
Arranging the adhesive layer having the flux function on the first electronic component;
The first solder bump is heated and pressed on the electrode so that the height A [μm] of the first solder bump is substantially the same as the thickness B [μm] of the adhesive layer having the flux function. And a contact step of deforming the first solder bump and bringing the first solder bump and the electrode into contact with each other.   The solder connection method according to claim 1, wherein the electrode has a substantially flat surface.   The solder connection method according to claim 1, wherein the electrode has a concave shape in a side view of the second electronic component by covering the periphery thereof with a coating layer.   The solder connection method according to claim 1, further comprising a curing step of curing the adhesive layer having the flux function.   The solder connection method according to any one of claims 1 to 4, wherein the adhesive layer having a flux function is composed of a resin composition containing a thermosetting resin and a compound having flux activity.   The solder connection method according to claim 1, wherein, in the contact step, after the solder bump is melted, heating is performed so that the thermosetting resin is cured.   When the adhesive having the flux function is heated from normal temperature to a molten state at a temperature rising rate of 10 ° C./min, the melt viscosity decreases at the beginning, and after reaching the minimum melt viscosity, further increases the characteristic. The solder connection method according to claim 1, wherein the minimum melt viscosity is 10 to 10,000 Pa · s or less.   An electronic apparatus comprising a solder connection portion connected by the solder connection method according to claim 1.

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