JP2017191945A - Mounting method of metal core column - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting method of metal core column capable of suppressing collapse of a metal core column, primary mounted on a semiconductor chip, or the like, in secondary mounting.SOLUTION: A mounting method of metal core column has a step of coating multiple electrodes 101, formed on a first board 100, with flux F, a step of placing the first joining surface 10A of a Cu core column 1A, covering the columnar core of Cu with solder, on each electrode 101 coated with flux F, and bonding the Cu core column 1A to the electrode 101 by heating at a temperature of fusing a solder, a step of sealing the periphery of the Cu core column 1A bonded to the electrode 101 with a resin composition 12, and a step of scraping the surface 120 of the resin composition 12 sealing the periphery of the Cu core column 1A, to expose the second joining surface 11A of the Cu core column 1A, and to arrange the height of respective Cu core columns 1A.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mounting method for a metal core column in which a metal core column in which a metal core is coated with solder is mounted on a substrate.

  In recent years, with the development of small information devices, electronic components to be mounted are rapidly downsized. For electronic components, a ball grid array (hereinafter referred to as “BGA”) in which electrodes are installed on the back surface is applied in order to cope with a reduction in connection terminals and a reduction in mounting area due to a demand for miniaturization.

  An electronic component to which BGA is applied includes, for example, a semiconductor package. In a semiconductor package, a semiconductor chip having electrodes is sealed with a resin. Solder bumps are formed on the electrodes of the semiconductor chip. This solder bump is formed by joining a solder ball to an electrode of a semiconductor chip. A semiconductor chip to which BGA is applied is placed on a circuit board by placing each solder bump on the circuit board so as to contact the electrode of the circuit board, and joining the solder bump and the electrode melted by heating.

  Now, with the recent progress of miniaturization of electronic components, the electrodes that are soldered portions of the electronic components are also becoming smaller. Therefore, the area that can be joined with solder is reduced, and the joining strength with only solder may be insufficient for joining reliability.

  Therefore, as a component fixing means for strengthening the joining by soldering, the solder ball is primarily mounted on the semiconductor chip, the semiconductor chip on which the solder bump is formed is secondarily mounted on the circuit board, and then the semiconductor chip and the circuit board are bonded. There has been proposed a technique for fixing a semiconductor chip or the like by covering a periphery of a solder joint by filling a resin called underfill between them (see, for example, Patent Document 1).

Japanese Patent No. 4757070

  With the recent progress in miniaturization of electronic components, the mounting area has been reduced and the electrode pitch has been reduced, so that the solder joints have become finer, and instead of spherical solder bumps, the core of the columnar metal has been replaced with solder. Coated metal core columns have been used.

  Even when the metal nucleus column is used, the metal nucleus column is primarily mounted on the semiconductor chip, the semiconductor chip on which the metal nucleus column is primarily mounted is secondarily mounted on the circuit board, and then between the semiconductor chip and the circuit board. The semiconductor chip can be fixed with the resin by filling the resin.

  However, in the step of secondary mounting the semiconductor chip on which the metal core column is primarily mounted on the circuit board, the metal core column bonded to the semiconductor chip in the primary mounting is heated to a temperature at which the solder melts. There was a possibility of falling.

  The present invention has been made to solve such a problem, and provides a method for mounting a metal nucleus column that can prevent a metal nucleus column that is primarily mounted on a semiconductor chip or the like from falling due to secondary mounting. The purpose is to provide.

  In order to solve the above-described problems, the present invention includes a step of applying a flux or solder paste to a plurality of electrodes formed on a substrate, and a metal core is coated with solder on each electrode to which the flux or solder paste is applied. Placing the first joining surface of the metal core column, heating the solder at a temperature at which the solder melts, joining the metal core column to the electrode, and sealing the periphery of the metal core column joined to the electrode with a resin composition And a step of shaving the surface of the resin composition sealing the periphery of the metal nucleus column to expose the second joint surface of the metal nucleus column and aligning the height of each metal nucleus column It is a column mounting method.

  In the present invention, the periphery of the metal core column bonded to the substrate in the primary mounting is sealed with the resin composition, so that the metal core column falls down even when heated to a temperature at which the solder melts in the secondary mounting. This can be suppressed.

It is process drawing which shows an example of the mounting method of Cu nucleus column of this Embodiment. It is process drawing which shows an example of the mounting method of Cu nucleus column of this Embodiment. It is a perspective view which shows an example of the Cu nucleus column of this Embodiment. It is sectional drawing which shows the typical structure of the Cu nucleus column of this Embodiment.

  Hereinafter, a Cu nucleus column mounting method will be described as an embodiment of a metal nucleus column mounting method of the present invention with reference to the drawings.

  1 and 2 are process diagrams showing an example of the mounting method of the Cu core column of the present embodiment, FIG. 3 is a perspective view showing an example of the Cu core column of the present embodiment, and FIG. It is sectional drawing which shows the typical structure of the Cu nucleus column of the form.

  The Cu core column mounting method of the present embodiment is a secondary mounting method in which the Cu core column bonded to the substrate by soldering in the primary mounting is secondary after the step called primary mounting in which the Cu core column is bonded to the substrate by soldering. In order not to fall by heating during mounting, a step of sealing the periphery of the Cu core column after the primary mounting with a resin composition is provided.

  First, the Cu nucleus column used in the mounting method of the Cu nucleus column of the present embodiment will be described with reference to FIGS.

  The Cu nucleus column 1A is an example of a metal nucleus column, and a Cu column 2A that is an example of a columnar metal nucleus having a predetermined size and securing a gap between a substrate constituting a semiconductor chip and a printed circuit board, etc. And a solder layer 3A which is an example of a coating layer covering the Cu column 2A. In the configuration in which the Cu core column 1A is cylindrical as shown in FIG. 3, one end face along the axial direction of the cylinder is the first joining face 10A, and the other joining face is the second joining face 11A. It is. In this example, the Cu column 2A is formed in a cylindrical shape, but is not limited to this, and may be, for example, a rectangular column.

  The Cu column 2A can have a composition of Cu alone or an alloy composition containing Cu as a main component. When the Cu column 2A is made of an alloy, the Cu content is 50% by mass or more. Moreover, as Cu column 2A, besides Cu, Ni, Ag, Bi, Pb, Al, Sn, Fe, Zn, In, Ge, Sb, Co, Mn, Au, Si, Pt, Cr, La, Mo Nb, Pd, Ti, Zr, and Mg may be composed of a single metal, an alloy, a metal oxide, or a metal mixed oxide.

  In the case of an alloy, the solder layer 3A is not particularly limited as long as it is an alloy composition of lead-free solder containing Sn as a main component. Moreover, as a solder layer, Sn plating film which consists of Sn100% may be sufficient. Examples thereof include Sn, Sn—Ag alloy, Sn—Cu alloy, Sn—Ag—Cu alloy, Sn—In alloy, Sn—Bi alloy, and those obtained by adding a predetermined alloy element thereto. In any case, the Sn content is 40% by mass or more. Examples of alloy elements to be added include Ag, Cu, In, Ni, Co, Sb, Ge, P, and Fe. Among these, the alloy composition of the solder layer is preferably a Sn-3Ag-0.5Cu alloy from the viewpoint of drop impact characteristics. Alternatively, Sn-Pb solder containing Pb may be used. In the Cu core column 1A, the solder layer 3A is formed by performing solder plating on the surface of the core 2A.

  In the Cu core column 1A, a diffusion prevention layer may be provided between the Cu column 2A and the solder layer 3A. The diffusion prevention layer is composed of one or more elements selected from Ni, Co, and the like, and prevents Cu constituting the Cu column 2A from diffusing into the solder layer 3A.

  The Cu column 2A preferably has a wire diameter (diameter) D2 of 20 to 1000 μm and a length L2 of 20 to 10,000 μm.

  The thickness of the solder layer 3A is not particularly limited, but for example, 100 μm (one side) or less is sufficient. Generally, it may be 20-50 μm.

  The Cu core column 1A preferably has a wire diameter (diameter) D1 of 22 to 2000 μm and a length L1 of 22 to 20000 μm.

  Next, with reference to FIG.1 and FIG.2, the mounting method of the Cu nucleus column of this Embodiment is demonstrated. As shown in FIG. 1A, a flux F is applied to the electrode 101 of the first substrate 100 such as a semiconductor chip. In the step of applying the flux F, the flux F is applied to a portion where the electrode 101 is provided by using a mask (not shown) provided with an opening in accordance with the arrangement of the electrode 101.

  As the flux, for example, a known material appropriately containing an organic acid, an amine, a surfactant, a base agent, a halogen, a thixotropic agent and a solvent may be used.

  The organic acid is added as an activator component in the flux. Organic acids include glutaric acid, phenyl succinic acid, succinic acid, malonic acid, adipic acid, azelaic acid, glycolic acid, diglycolic acid, thioglycolic acid, thiodiglycolic acid, propionic acid, malic acid, tartaric acid, dimer acid , Hydrogenated dimer acid, trimer acid and the like.

  The amine is added as an active auxiliary component in the flux, and affects the speed of wetting and spreading of the flux. Examples of the amine include imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, polyetheramine, polyoxyalkyleneamine, polyoxyethyleneamine, polyoxypropyleneamine, Examples include 2-ethylaminoethanol, diethanolamine, triethanolamine, and amino alcohol.

  Examples of the base agent include polyethylene glycol, polyethylene glycol-polypropylene glycol copolymer, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene beef tallow ester and the like.

  The solvent is selected from generally known glycol ether compounds. Examples of the solvent include hexylene glycol, hexyl diglycol, 1,3-butanediol, octanediol, alkylene oxide / resorcin copolymer, 2-ethyl-1,3-hexanediol, 2-ethylhexyl diglycol, phenyl Glycol, butyltriglycol, terpineol, etc. are mentioned.

  Next, as shown in FIG. 1B, the first bonding surface 10A of the Cu core column 1A is placed on the electrode 101 to which the flux F is applied. In the step of placing the Cu nucleus column 1A on the substrate 100, a mask (not shown) provided with an opening into which the Cu nucleus column 1A is inserted is used to place the Cu nucleus column 1A in a predetermined direction at a position where the electrode 101 is provided. To be put on.

  Next, as shown in FIG. 1C, the first substrate 100 on which the Cu core column 1A is mounted is heated to a predetermined temperature at which the solder layer 3A is melted using a reflow furnace, The electrode 101 of the substrate 100 and the Cu nucleus column 1A are joined with solder.

  After the Cu core column 1A is joined to the electrode 101 with solder, the flux residue remaining at the joint between the Cu core column 1A and the electrode 101 is removed by washing. In addition, when the flux F is a residue-free thing, washing | cleaning is not performed.

  Next, as shown in FIG. 1D, the resin composition 12 is filled around the Cu core column 1 </ b> A bonded to the electrode 101 of the first substrate 100. The resin composition 12 includes a thermosetting resin that is cured by heating and a curing agent that accelerates the curing of the resin.

  When the resin composition is in a liquid state at normal temperature, the resin composition 12 is filled around the Cu core column 1A using a capillary phenomenon. When the resin composition is solid at room temperature, after being dissolved by heating, pressure is applied to fill the resin composition 12 around the Cu core column 1A. In any case, after the resin composition 12 is filled, the resin composition 12 filled around the Cu core column 1A is heated to a curing temperature to cure the resin composition 12, whereby the Cu core column 1A is cured. Is sealed with a resin composition 12 to form a support structure.

  Examples of the thermosetting resin include an epoxy resin and a cyanate resin. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, bisphenol Z type epoxy resin and the like. Type epoxy resin, phenol novolac type epoxy resin, novolac type epoxy resin such as cresol novolak type epoxy resin, biphenyl type epoxy resin, xylylene type epoxy resin, arylalkylene type epoxy resin such as biphenyl aralkyl type epoxy resin, naphthalene type epoxy resin, Binaphthyl type epoxy resin, anthracene type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornene type Carboxymethyl resins, adamantane type epoxy resins and fluorene type epoxy resins and the like.

  The cyanate resin is a novolak-type cyanate resin, a bisphenol A-type cyanate resin, a bisphenol E-type cyanate resin, a bisphenol-type cyanate resin such as a tetramethylbisphenol F-type cyanate resin, a naphthol-aralkyl-type polyvalent naphthol, and a cyanogen halide. Cyanate resin obtained by reaction, dicyclopentadiene type cyanate resin, biphenyl alkyl type cyanate resin, etc. can be mentioned.

  In addition to the epoxy resin and the cyanate resin, the resin contained in the resin composition 12 includes a novolak type phenol resin such as a phenol novolak resin, a cresol novolak resin, a bisphenol A novolak resin, an unmodified resole phenol resin, tung oil, linseed oil, Phenol resin such as resol type phenol resin such as oil modified resol phenol resin modified with walnut oil, resin having triazine ring such as urea (urea) resin, melamine resin, unsaturated polyester resin, bismaleimide resin, polyurethane resin, A diallyl phthalate resin, a silicone resin, a resin having a benzoxazine ring, a polyimide resin, a polyamideimide resin, a benzocyclobutene resin, or the like may be used.

  As the resin contained in the resin composition 12, one of these may be used alone, two or more may be used in combination, and one or two or more thereof may be used in combination with their prepolymer. May be.

  Examples of the curing agent include dicyandiamide, organic acid dihydrazide, imidazoles, amine adduct curing agent, vinyl ether block carboxylic acid, onium salt, ketimine compound, microencapsulated imidazole, acid anhydride, and phenols. Acid anhydrides include phthalic anhydride, maleic anhydride, citraconic anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 4-methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, Methylbicyclo [2.2.1] heptane-2,3-dicarboxylic anhydride, bicyclo [2.2.1] heptane-2,3-dicarboxylic anhydride, 1,2,3,6-tetrahydrophthalic anhydride, 3, 4,5,6-tetrahydrophthalic anhydride, ethylene glycol bisanhydro trimellitate, glycerin bis anhydro trimellitate monoacetate, tetrapropenyl succinic anhydride.

  Next, as shown in FIG. 1 (e), the surface 120 of the resin composition 12 filled and cured around the Cu core column 1A is shaved, and the second bonding surface 11A of the Cu core column 1A is removed from the resin composition. 12, and the height of each Cu core column 1 </ b> A is made uniform to smooth the second bonding surface 11 </ b> A and the surface 120 of the resin composition 12. In addition, regarding the grinding | polishing processing method which grinds the surface 120 of the resin composition 12, the grinding technique of a silicon wafer can be expand | deployed and the grinding technique etc. which used the diamond wheel can be applied to this invention. The polishing method used in the present invention is not limited to the above.

  Next, as illustrated in FIG. 2A, a bonding layer 112 is formed on the electrode 111 of the second substrate 110 such as a circuit board. The bonding layer 112 is formed, for example, by forming a solder layer of 100% Sn or a solder layer containing Sn as a main component and containing Cu or the like on the electrode 111 by a known plating method, and applying a flux to the solder layer. Formed with.

  Next, as shown in FIG. 2B, the second bonding surface 11A of the Cu nucleus column 1A primarily mounted on the first substrate 100 as described above is formed on the electrode 111 on which the bonding layer 112 is formed. And using a reflow furnace, the solder constituting the bonding layer 112 is heated to a predetermined temperature at which the solder melts, and the electrode 111 of the second substrate 110 and the Cu core column 1A are bonded by solder.

  As shown in FIGS. 2A and 2B, after the primary mounting in which the Cu nucleus column 1A is joined to the first substrate 100 with solder, the second joining surface 11A of the Cu nucleus column 1A is In the step of performing the secondary mounting in which the substrate 110 is mounted on the second substrate 110 and joined by soldering, the joining portion between the Cu core column 1A joined in the primary mounting and the electrode 101 of the first substrate 100 is also heated. In the secondary mounting, the first substrate 100 to which the Cu nucleus column 1A is bonded is placed on the second substrate 110 with the Cu nucleus column 1A facing downward. In addition to the printed circuit board, the second board 110 may be any existing board such as an interposer, and may be an electronic component other than the board. A method of laminating the electronic component or the like at the time of secondary mounting may be used.

  After the primary mounting in which the Cu core column 1A is joined to the first substrate 100 with solder, when the secondary mounting is performed without providing the support structure of the resin composition 12 around the Cu core column 1A, the Cu core column At the time of melting, the solder on the upper side of 1A flows to the lower outer peripheral portion along the side surface of the Cu core column 1A, and the amount of solder on the upper portion of the Cu core column 1A is reduced. Intermetallic compounds (IMC) grow. Since the intermetallic compound and the solder cannot be joined, the amount of solder is reduced, and on the upper part of the Cu core column 1A where the intermetallic compound that is not joined to the solder is formed, the joining performance is deteriorated in the secondary mounting. In this state, the Cu core column 1 </ b> A may fall down by being heated to a temperature at which the solder is melted in the secondary mounting. Further, when the solder on the upper part of the Cu core column 1A flows to the lower outer periphery when it melts, the solder gathers on the lower outer periphery of the Cu core column 1A by gravity, and the amount of solder supplied becomes excessive on the lower outer periphery of the Cu core column 1A. In the substrate having a pitch, the Cu core columns 1A are also connected to each other by soldering.

  On the other hand, after the primary mounting, the periphery of the Cu core column 1A is sealed with the resin composition 12, and a support structure is formed around the Cu core column 1A, so that the solder is melted in the secondary mounting. Even if the solder is melted by heating up to the temperature, the Cu core column 1A cannot be physically moved by the resin composition 12, and the periphery of the Cu core column 1A is sealed by the resin composition 12. Thereby, it can prevent that the solder of Cu upper column 1A upper part flows into a lower outer peripheral part at the time of a fusion | melting, and Cu core column 1A falls and it is suppressed that a solder bridges.

  Furthermore, the present invention can be handled like a package by dicing a resin-sealed substrate such as a silicon wafer after the primary mounting.

  In the above description, the case where the flux F is applied to the electrode 101 of the first substrate 100 has been described. However, the mounting of the present invention can be performed even when a solder paste kneaded with solder powder and flux is applied instead of the flux F. The method can be applied. The composition of the solder powder used for the solder paste is not particularly limited as is the case with the composition of the solder layer 3A, and the same composition as the solder used for the solder layer 3A may be used, or another composition may be used. The solvent such as flux used for the solder paste is not particularly limited as long as it can be used in a paste form.

  Further, although the case where the flux F is applied to the solder layer as the bonding layer 112 formed on the electrode 111 of the second substrate 110 has been described, even when the bonding layer 112 is formed by applying solder paste to the electrode 111. The secondary mounting described above can be performed. Also for the solder paste forming the bonding layer 112, the composition of the solder powder used for the solder paste is not particularly limited as in the case of the solder layer 3A, and the same composition as the solder used for the solder layer 3A may be used. Other compositions may be used. The solvent such as flux used for the solder paste is not particularly limited as long as it can be used in a paste form.

  Furthermore, conventionally, as a method other than the present invention for solving the problem that the Cu core column 1A falls, a solder having a high melting point is used for the solder layer 3A, and in the secondary mounting, the solder used in the primary mounting is different from the solder used in the primary mounting. In addition, a method of joining the Cu core column 1A using a solder paste having a low melting point is also performed. In the case of mounting by the above method, the heating temperature at the time of secondary mounting can be lower than the heating temperature at the time of primary mounting. It is possible to suppress the column 1A from falling.

  In the present invention, after the primary mounting, a solder having a melting point lower than that of the solder layer 3A coated with the Cu core column 1A is applied by applying the mounting method described above in which the periphery of the Cu core column 1A is sealed with the resin composition 12. Alternatively, when the bonding layer 112 is formed using a solder paste and the secondary mounting is performed, the problem of the present invention can be solved more effectively. Further, instead of solder or solder paste, a conductive adhesive may be used as the bonding layer 112 in the secondary mounting. Since the conductive adhesive is cured by heating at a temperature lower than the melting point of the solder layer 3A coated on the Cu core column 1A, the problem of the present invention can be solved more effectively.

  The present invention is applied to a process of mounting a columnar metal core column coated with solder on a substrate.

  DESCRIPTION OF SYMBOLS 1A ... Cu nucleus column, 2A ... Cu column, 3A ... Solder layer, 10A ... 1st joining surface, 11A ... 2nd joining surface, 12 ... Resin composition, DESCRIPTION OF SYMBOLS 100 ... 1st board | substrate, 101 ... Electrode, 110 ... 2nd board | substrate, 111 ... Electrode, 112 ... Bonding layer

Claims (2)

Applying flux or solder paste to a plurality of electrodes formed on the substrate;
A first joint surface of a metal core column in which a metal core is coated with solder is placed on each electrode coated with the flux or solder paste, and the metal core column is attached to the electrode by heating at a temperature at which the solder melts. Joining, and
Sealing the periphery of the metal core column bonded to the electrode with a resin composition;
Scraping the surface of the resin composition sealing the periphery of the metal nucleus column to expose the second joint surface of the metal nucleus column and aligning the height of each metal nucleus column. The mounting method of the metal core column. The substrate in which the periphery of the metal nucleus column is sealed with a resin composition, the second joint surface of the metal nucleus column is exposed, and the height of each of the metal nucleus columns is aligned is another substrate. The method of mounting a metal nucleus column according to claim 1, further comprising a step of bonding the second bonding surface of the metal nucleus column to the other substrate.

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