JP2001111235A - Method of manufacturing flip-chip mounting high-density multilayer printed interconnection board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method of manufacturing a high-density multilayer printed interconnection board which has excellent heat radiation properties and hole connection reliability. SOLUTION: Pads, to which the bumps of a flip-chip, are formed on the surface layer of a multilayer printed interconnection board on which the flip-chip is mounted. The pads are connected to the circuits of respective layers with through-hole conductors with hole diameters of 25-300 μm. The inner layer circuits spread from the center parts into the surroundings of the printed interconnection board. The inner circuits are connected to solder ball pads, at least on the surface via the through-hole conductors. With this constitution, a method of manufacturing a high density multilayer printed interconnection board which has superior heat radiation properties and hole connection reliability and the high-density through-holes can be provided. Furthermore, by employing multifunctional ester cyanate resin composition as thermosetting resin, a high- density multilayer printed interconnection board which has superior heat-resistant properties, electrical insulating properties after a pressure cooker treatment, migration-resistant properties, etc., can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density copper foil having at least three layers of copper foil, wherein each layer is connected by a through-hole conductor having a hole diameter of 25 to 300 .mu.m drilled by at least one hole with a laser. The present invention relates to a method for manufacturing a multilayer printed wiring board. The obtained printed wiring board is mounted on a flip chip as a high-density small printed wiring board.
It is mainly used for new lightweight semiconductor plastic packages.

[0002]

2. Description of the Related Art Hitherto, in high-density printed wiring boards used for semiconductor plastic packages and the like, through holes for through holes have been drilled. In recent years, the diameter of drills has become smaller and smaller, and the hole diameter has become 180 μm or less.When drilling such small holes, the drill diameter is small, so the drill bends, breaks, and the processing speed is slow when drilling. However, there are problems such as productivity and reliability. In addition, if holes of the same size are made in advance by using a negative film on the upper and lower copper foils by a predetermined method, and a through-hole that penetrates the upper and lower sides with a carbon dioxide gas laser is to be formed, the position of the inner layer copper foil will shift. In addition, there have been disadvantages such as displacement of the positions of the upper and lower holes, poor connection, and the inability to form front and rear lands. Further, when a copper foil was used as the inner layer, even if the surface layer copper foil was removed by etching to form a hole with low energy, the inner layer copper foil could not be formed and a through hole could not be formed. Even with a mechanical drill
180μm or less through hole can be formed, but drill bends,
Copper plating soaked due to breakage of glass fiber at the time of drilling was seen, and the reliability between the hole walls was just one step away. Also,
A high-density printed wiring board having a hole diameter of 180 μm or less can be formed by a photo via method or the like, but a printed wiring board obtained by the present invention, in which all conduction is formed by through holes, could not be produced. Also, when making with a mechanical drill, if the distance between the hole walls becomes 100-200 μm high density, the glass fiber cracks by the drill, plating infiltration at the time of copper plating occurs, and there is a problem in migration resistance etc. Was.

[0003]

SUMMARY OF THE INVENTION The present invention is directed to a method of manufacturing a high-density multilayer printed circuit board for flip chip mounting, in which all layers are connected by through holes having a hole diameter of 300 μm or less, particularly 180 μm or less. About.

[0004]

According to the present invention, in a multilayer printed wiring board on which flip chips are mounted, pads for connecting flip chip bumps are formed on a surface layer, and the pads are formed by through-hole conductors having a hole diameter of 25 to 300 μm. The circuit of the inner layer is a circuit extending from the center of the printed wiring board to the periphery, and the inner layer circuit is connected to the solder ball pad at least on the back surface by a through hole conductor. Provided is a method for manufacturing a printed wiring board. The method for producing a high-density printed wiring board provided by the present invention is a method for producing a high-density multilayer printed wiring board for flip-chip mounting having at least three copper foil layers comprising the following steps. . a. For a through hole with a hole diameter of 80 μm or more and 180 μm or less on the double-sided copper-clad board (a), place an auxiliary material for drilling on the copper foil surface, and directly irradiate a carbon dioxide laser with sufficient energy to process the copper foil. Drilling (B), then, if necessary, etching and removing a part of the copper foil and, at the same time, dissolving and removing the copper foil burrs generated around the hole; B. If necessary, a hole diameter of 25 μm or more and less than 80 μm Through-holes are excimer laser, YAG laser, and / or through-holes with a diameter greater than 180 μm and less than 300 μm are drilled with a mechanical drill, and then the surface and the inside of the holes are plated with copper (d ₁ ); c. After forming a circuit on the lower surface side copper foil which is the inner layer of the board, prepreg and copper foil are arranged in this order on the circuit surface side and laminated and formed. D. Repeat the above steps a, B and c as many times as necessary. Obtaining a multilayer board, said multilayer The conductor (s) of the hole passing through the front and back of the multilayer board is electrically connected to the circuit (t) of each inner layer, e. The solder ball pad (l) on the back surface of the multilayer board and the flip chip pad (u) on the front surface A hole is made at the position where the hole is to be formed. If necessary, a part of the copper foil is removed by etching, and at the same time, the copper burrs around the hole are dissolved and removed. A circuit is formed and a flip chip pad and a solder ball pad are laminated. A step of copper-plating a hole penetrating the front and back to electrically conduct through a conductor; f. At least a flip chip mounting pad (u);
A process of applying precious metal plating to parts other than the solder ball pad part (l).

A through hole having a hole diameter of 25 μm or more and 180 μm or less is formed by a laser. An excimer laser or a YAG laser is preferable for a pore diameter of 25 μm or more and less than 80 μm. 80 μm or more 1
A through hole with a pore size of 80 μm or less is provided with a metal oxide treatment layer or a chemical treatment layer on the copper foil surface, or a metal compound powder, carbon powder, or metal having a melting point of 900 ° C. or more and a binding energy of 300 kJ / mol or more. One or two or more types of powder
~ 97vol% of the coating film, or a sheet-like coating thereof, suitably placed on the copper foil surface with a total thickness of 30 ~ 200μm, the output of the carbon dioxide laser, preferably 20 ~ 60
A carbon dioxide laser of energy selected from mJ / pulse is directly irradiated to form a through hole for a through hole. After the through holes are formed, the surface of the copper foil can be deburred by mechanical polishing.However, in order to completely remove the deburr, preferably, both surfaces of the copper foil are etched flat and the original metal is removed. It is preferable to etch away the copper burrs protruding in the hole by partially etching away the foil in the thickness direction. According to this method, since the copper foil becomes thinner, in the circuit formation of the fine wire of the front and back copper foil obtained by plating up by the subsequent metal plating, there is no occurrence of defects such as short-circuits and pattern breaks, and high density A printed wiring board can be created. At the time of thinning copper by etching this front and back copper foil,
The resin layer adhering to the surface of the inner copper foil exposed inside the hole is preferably subjected to at least a gas phase treatment and then etched away. 50% by volume or more, preferably 90% by volume, of copper
Filling by volume% or more facilitates resin filling during lamination molding. In addition, in the case of the last through hole, a hole having extremely excellent connection can be obtained by connecting the copper foil in the surface layer and the copper foil inside the hole. In addition, the processing speed is much faster than when drilling, the productivity is good, and the economy is excellent. Further, it is preferable to use a through hole having a hole diameter of 200 μm as the through hole around the flip chip for connecting the inner and outer copper foils. This hole is preferably drilled with a mechanical drill.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a method for manufacturing a high-density printed wiring board for mounting a flip chip having at least three or more copper layers. The flip-chip bump connection pad is connected to each inner layer with a through-hole conductor with a hole diameter of 25 μm or more and 300 μm or less. The circuit extending from each inner layer to the periphery is finally a front-back through-hole through-hole circuit for the solder ball pad on the back. Connected.
In order to increase the density, the diameter of the through-hole formed in the flip-chip connection pad is preferably small, and generally 25 to 180 μm. The through-holes having a hole diameter of 25 μm or more and less than 80 μm are preferably formed by an excimer laser or a YAG laser. For through-holes with a hole diameter of 80 μm or more and 180 μm or less, a metal oxide treatment layer or a chemical treatment layer is provided on the copper foil surface, or an auxiliary material is arranged, and a carbon dioxide laser energy selected from 20 to 60 mJ / pulse is preferably used. To form a through hole.

The present invention first uses a double-sided copper-clad laminate,
A pad for mounting a flip chip is formed on this surface. This pad is formed on the through hole immediately below the flip chip, or is formed so as to be connected to the through hole while avoiding the through hole. To form a pad on the through hole, fill the inside of the through hole with copper plating, or fill the inside of the hole with a filler resin with metal filler after normal through hole plating, exposing the metal filler surface Later, electroless plating and precious metal plating are performed thereon to form pads. The through hole is connected to the inner copper foil of the inner layer by copper plating, and a circuit is formed so as to spread from the connected portion to the periphery of the printed wiring board. The copper foil of the second layer circuit is chemically treated as necessary, a B-stage sheet is placed outside the circuit, the copper foil is placed outside the circuit, and laminated under heat, pressure, and preferably under vacuum. Multi-layer. Thereafter, similarly, through-holes are formed, copper plating is formed so as to extend the lower circuit to the periphery, and a B-stage sheet and copper foil are arranged and laminated to form a multilayer board. In the production of this multilayer board, through-hole plating is performed, and when the thickness of the copper foil of the upper and outer layers becomes 12 μm or more, the copper foil is etched with a chemical solution, preferably 1 μm.
Make it 2 μm or less. When the thickness is 12 μm or less, there are advantages that a fine circuit can be formed and that a carbon dioxide gas laser can be easily formed.

In drilling by a carbon dioxide laser,
Provide a metal oxide treatment layer or a chemical treatment layer on the surface to be irradiated with a laser, or have a melting point of 900 ° C and a binding energy of 300 kJ.
/ mol or more of metal oxide powder, carbon, or a mixture of a metal powder and a water-soluble resin, applied as a coating film, or obtained by attaching a total thickness of 30 to 200 μm to one surface of a thermoplastic film. Arrange an auxiliary sheet for drilling, preferably adhere to the copper foil surface, irradiate carbon dioxide laser directly on the copper foil surface from above, and process and remove the copper foil, forming through holes for through holes Preferably, a method is used.

[0009] The auxiliary sheet for laser drilling of the present invention comprises:
It can be used as it is. However, it is preferable to place it on a copper-clad plate and make the hole as close as possible when drilling holes in order to improve the shape of the holes. Generally, the sheet is fixed and adhered to the copper-clad board by a method such as pasting it with tape or the like, but in order to adhere more completely, the obtained sheet is attached to the surface of the copper-clad board. , Face the resin adhered,
Laminate under heat and pressure, or resin surface 3
By pre-wetting the μm or less with water and then laminating at room temperature under pressure, the adhesion to the copper foil surface becomes good, and a good hole shape can be obtained.

As the resin composition, a resin composition that is not water-soluble and can be dissolved in an organic solvent can also be used. However, the carbon dioxide laser irradiation may cause the resin to adhere around the holes, and the removal of the resin requires an organic solvent instead of water, which is troublesome in processing, and also causes contamination in a post-process. It is not preferable because it causes problems.

The double-sided copper-clad board used in the present invention may be a double-sided copper-clad board having a known organic or inorganic substrate-reinforced two-layer copper foil layer on both sides, or a film-based board. is there.
As the substrate, generally known organic and inorganic woven fabrics and nonwoven fabrics can be used. Specifically, as inorganic fibers,
Fibers such as E, S, D, and M glass are exemplified. Examples of the organic fiber include a cloth using fibers of wholly aromatic polyamide, liquid crystal polyester, and polybenzazole. These may be mixed.

As the resin of the thermosetting resin composition used in the double-sided copper-clad laminate and prepreg used in the present invention, generally known thermosetting resins are used. Specifically, epoxy resin, polyfunctional cyanate ester resin,
Examples thereof include a polyfunctional maleimide-cyanate ester resin, a polyfunctional maleimide resin, and an unsaturated group-containing polyphenylene ether resin, and one or more of them are used in combination. In view of the shape of the through-hole in processing by high-output carbon dioxide laser irradiation, the glass transition temperature
A thermosetting resin composition of 150 ° C. or higher is preferable, moisture resistance,
A polyfunctional cyanate resin composition is preferred in terms of migration resistance, electrical properties after moisture absorption, and the like.

The polyfunctional cyanate compound which is a preferred thermosetting resin component of the present invention is a compound having two or more cyanato groups in a molecule. Specific examples include 1,3- or 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-, 1,8-, 2 , 6- or 2,7-
Dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4-dicyanatobiphenyl, bis (4-dicyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, 2,2- Bis (3,5-dibromo-4-cyanatophenyl) propane, bis (4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) sulfone, tris (4-cy (Anatophenyl) phosphite, tris (4-cyanatophenyl) phosphate, and cyanates obtained by reacting novolak with cyanogen halide.

In addition to these, Japanese Patent Publication Nos. 41-1928 and 43-1846
8, polyfunctional cyanate compounds described in JP-A-44-4791, JP-A-45-11712, JP-A-46-41112, JP-A-47-26853 and JP-A-51-63149 can also be used. Further, a prepolymer having a molecular weight of 400 to 6,000 and having a triazine ring formed by trimerization of a cyanato group of these polyfunctional cyanate compounds is used. This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate ester monomer with a catalyst such as an acid such as a mineral acid or a Lewis acid; a base such as a tertiary amine such as sodium alcoholate; or a salt such as sodium carbonate. It can be obtained by: The prepolymer also contains some unreacted monomers and is in the form of a mixture of the monomer and the prepolymer, and such a raw material is suitably used for the purpose of the present invention. Generally, it is used after being dissolved in a soluble organic solvent.

As the epoxy resin, a generally known epoxy resin can be used. Specifically, liquid or solid bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin; butadiene, pentadiene, vinylcyclohexene, dicyclopentyl ether, etc. And polyglycidyl compounds obtained by reacting a polyol, a hydroxyl-containing silicone resin with an epohalohydrin, and the like. These may be used alone or in combination of two or more. A generally known polyimide resin can be used. Specific examples include a reaction product of a polyfunctional maleimide and a polyamine, and a polyimide having a terminal triple bond described in JP-B-57-005406. These thermosetting resins may be used alone, but it is preferable to use them in an appropriate combination in consideration of the balance of properties.

Various additives can be added to the thermosetting resin composition of the present invention, if desired, as long as the inherent properties of the composition are not impaired. These additives include polymerizable double bond-containing monomers such as unsaturated polyesters and prepolymers thereof; polybutadiene, epoxidized butadiene, maleated butadiene, butadiene-
Low molecular weight liquid to high molecular weight elastic rubbers such as acrylonitrile copolymer, polychloroprene, butadiene-styrene copolymer, polyisoprene, butyl rubber, fluororubber, natural rubber; polyethylene, polypropylene, polybutene, poly-4-methyl Penten, polystyrene, AS
Resin, ABS resin, MBS resin, styrene-isoprene rubber, polyethylene-propylene copolymer, 4-fluoroethylene-6-fluoroethylene copolymers; polycarbonate,
Polyphenylene ether, polysulfone, polyester, high molecular weight prepolymer or oligomer such as polyphenylene sulfide; polyurethane and the like,
Used as appropriate. In addition, other known inorganic and organic fillers, dyes, pigments, thickeners, lubricants, defoamers, dispersants, leveling agents, photosensitizers, flame retardants, brighteners, polymerization inhibitors,
Various additives such as a thixotropy-imparting agent are appropriately used in combination as needed. If necessary, the compound having a reactive group is appropriately blended with a curing agent and a catalyst. In particular, for laser processing, it is preferable to add an inorganic filler to the resin composition and further add a black dye or pigment.

The thermosetting resin composition of the present invention can be cured by heating itself, but has a low curing rate and is inferior in workability and economic efficiency. Can be used. The amount used is 0.005 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the thermosetting resin.

The auxiliary material used in the present invention has a melting point of 90.
As the metal compound having a binding energy of 300 kJ / mol or more at 0 ° C. or more, generally known metal compounds can be used. Specifically, as the oxide, titania such as titanium oxide, magnesia such as magnesium oxide, iron oxide such as iron oxide, nickel oxide such as nickel oxide, manganese dioxide, zinc oxide such as zinc oxide , Silicon oxide, aluminum oxide, rare earth oxides, cobalt oxides such as cobalt oxide, tin oxides such as tin oxide, and tungsten oxides such as tungsten oxide. Examples of the non-oxide include generally known ones such as silicon carbide, tungsten carbide, boron nitride, silicon nitride, titanium nitride, aluminum nitride, barium sulfate, and rare earth oxysulfide. In addition, carbon can also be used. Further, various glasses which are a mixture of the metal oxide powders may be mentioned. In addition, carbon powders may be mentioned, and further, simple substances such as silver, aluminum, bismuth, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, palladium, antimony, silicon, tin, titanium, vanadium, tungsten, zinc and the like. An alloy metal powder is used. These may be used alone or in combination of two or more. The average particle size is
Although not particularly limited, 1 μm or less is preferable.

Since the molecules are dissociated or melted and scattered by the irradiation of the carbon dioxide laser, the metal does not adhere to the hole walls and the like, and does not adversely affect the semiconductor chip and the hole wall adhesion. preferable. Since Na, K, Cl ions and the like particularly adversely affect the reliability of the semiconductor, those containing these components are not suitable. The compounding amount is 3 to 97% by volume, preferably 5 to 95% by volume, and is preferably mixed with the water-soluble resin and uniformly dispersed.

The water-soluble resin of the auxiliary material is not particularly limited, but when kneaded, applied to the copper foil surface and dried,
Alternatively, in the case of a sheet shape, a material that does not lose peeling is selected. For example, generally known materials such as polyvinyl alcohol, polyester, polyether and starch are used.

The method for preparing a metal compound powder, a carbon powder, or a composition comprising a metal powder and a resin is not particularly limited, but it is kneaded at a high temperature without a solvent using a kneader or the like, and extruded into a sheet on a thermoplastic film. A method of dissolving a water-soluble resin in water, adding the powder to the mixture, stirring and mixing the mixture uniformly, and applying the mixture to a thermoplastic film as a paint, followed by drying to form a film. And other generally known methods. The thickness is not particularly limited, but is generally used in a total thickness of 30 to 200 μm. Alternatively, it is possible to form a hole similarly after providing a metal oxide treatment layer on the surface of the copper foil, but it is preferable to use the above-mentioned auxiliary material also from the viewpoint of the hole shape and the like. On the back side, it is preferable to use a backup sheet in which a water-soluble resin is adhered on a metal plate on the back side in order to avoid damage to the table of the carbon dioxide laser when the through-hole is formed.

When laminating on the copper foil surface under heating and pressure, both the auxiliary material and the backup sheet have the coating resin layer facing the copper foil surface, and the temperature is generally 40 to 150 ° C. with a roll.
Lamination is preferably performed at a temperature of 60 to 120 ° C. and a linear pressure of generally 0.5 to 20 kg, preferably 1 to 10 kg, and the resin layer is melted and brought into close contact with the copper foil surface. The choice of temperature depends on the melting point of the water-soluble resin used, and also depends on the linear pressure and the laminating speed.
Laminate at ~ 20 ° C higher temperature. In the case of close contact at room temperature, the surface of the coating resin layer of 3 μm or less is moistened with water before lamination to dissolve a small amount of the water-soluble resin, and is laminated under the same pressure. The method of moistening with water is not particularly limited, but, for example, a method in which water is continuously applied to the coating resin surface by a roll, and thereafter, a method of continuously laminating the surface of the copper-clad laminate, the water is sprayed. A method of continuously spraying the coating film surface and then continuously laminating the surface of the copper-clad laminate may be used.

The substrate-reinforced copper clad board is first impregnated with a thermosetting resin composition and dried to form a B stage,
Create a prepreg. Next, a predetermined number of the prepregs are stacked, copper foils are arranged on both sides, and laminated under heat and pressure to form a copper clad board. The thickness of the copper foil is 3 to 12 μm for a double-sided copper-clad laminate, and 5 to
18 μm. Double-sided foils can also be used.

The multilayer board is preferably made by drilling a through hole with a laser on a double-sided copper-clad laminate reinforced with a glass cloth base material, performing desmear treatment if necessary, applying copper plating, and applying copper plating inside the hole. At least 90% by volume, a circuit is formed on the lower (back) surface of the inner layer, and if necessary, after a copper foil surface treatment, a glass substrate reinforcing prepreg of the B stage is arranged thereon. Then, a copper foil is placed on the outside and laminated and formed under heat, pressure and preferably under vacuum to form a copper-clad multilayer board. This is repeated to form a multilayer board having a predetermined layer.

When forming a through hole having a hole diameter of 80 to 180 μm,
Providing a metal oxide treatment layer on the copper foil on the surface of the double-sided copper-clad laminate or disposing the above-mentioned auxiliary material, from above, narrowed down to the desired diameter, preferably selected from 20 to 60 mJ / pulse By directly irradiating a high-output energy carbon dioxide laser beam, the copper foil is processed and drilled. When a hole is formed by irradiating a carbon dioxide laser with an output of 20 to 60 mJ / pulse, burrs occur around the hole. This is not a problem for a double-sided copper-clad laminate, and copper plating is performed as it is to obtain 50% by volume or more, preferably 90% by volume of the inside of the hole.
The above is plated with copper, and the surface layer is also plated at the same time to increase the copper foil thickness.
It is 18 μm or less, preferably 12 μm or less. A circuit is formed on the copper foil on the lower surface serving as the inner layer, and a copper foil surface treatment is performed as necessary.On this, preferably, a glass cloth base material prepreg is arranged, and the copper foil is placed on the outside thereof, and laminated and formed. It is a multilayer board. In the present invention, since all the conduction of the upper and lower layers is performed by through holes, the holes are successively plated with copper to form a multilayer, so that the surface layer of the copper foil becomes thick. In order to carry out drilling with a carbon dioxide laser, it is preferable to etch the surface copper foil to 12 μm or less. By repeating this, a multilayer board having a target layer is prepared. The inner copper foil extends a circuit from the lower part of the flip chip mounting portion to the periphery to form a land. A through hole is made at the center of the land to connect the layers, and also to a circuit portion connected to the solder ball pad on the back surface. By doing so, the heat generated from the flip chip is radiated to the upper surface, from the lower surface through the flip chip heat radiation bumps, through the inner layer circuit spreading around, through the solder balls on the lower surface, and onto the motherboard printed wiring board Dissipates heat so that it diffuses. Of course, this circuit is also used for signal propagation.

In order to form a very high-density circuit, it is necessary to reduce the thickness of the surface copper foil including the copper foil serving as the inner layer. By etching both surfaces mechanically or chemically with two-dimensional surface, and removing part of the thickness of the original metal foil,
At the same time, burrs are removed, and the obtained copper foil is suitable for forming a fine pattern, and forms a through hole for through-hole plating in which the copper foil around the hole suitable for a high-density printed wiring board remains. In this case, etching is more preferable than mechanical polishing in terms of removing burrs from holes and dimensional change due to polishing.

The method of etching and removing copper burrs generated in the holes according to the present invention is not particularly limited. For example, Japanese Patent Application Laid-Open Nos. 02-22887, 02-22896, 02-25089 and 02-2.
5090, 02-59337, 02-60189, 02-166789, 03-25
995, 03-60183, 03-94491, 04-199592, 04-263
No. 488 discloses a method of dissolving and removing a metal surface with a chemical (referred to as a SUEP method). The etching rate is generally 0.02 to 1.0 μm / sec.

The carbon dioxide laser is in the infrared wavelength range.
Wavelengths of 9.3 to 10.6 μm are commonly used. The output is preferably made by drilling a hole in the copper foil at 20-60 mJ / pulse. An excimer laser generally has a wavelength of 248 to 308 μm, and a YAG laser generally has a wavelength of 351 to 355 μm. This wavelength is not limited to this. The processing speed of the carbon dioxide laser is remarkably fast and economical.

When drilling through holes with a carbon dioxide laser,
It is good to irradiate energy selected from 20 to 60 mJ / pulse from the beginning to the end. Of course, it is possible to change the energy during drilling within this energy. When removing the surface copper foil, by selecting a higher energy, the number of irradiation shots can be reduced and the efficiency is good.
When processing the intermediate resin layer, high output is not necessarily required, and it can be appropriately selected depending on the base material and the resin. For example, the output can be selected from 10 to 35 mJ / pulse. Of course, high-power processing can be performed until the end. The processing conditions can be changed with or without the inner layer copper foil inside the hole.

In most cases, a resin layer of about 1 μm remains in the inner layer copper foil inside the hole processed by the carbon dioxide laser. Further, when a hole is drilled with a mechanical drill, smear may remain. By removing this resin layer, the connection reliability between the further copper plating and the copper in the inner and outer layers is improved. In order to remove the resin layer, generally known treatments such as desmear treatment can be performed.However, when the liquid does not reach the inside of the small-diameter hole, the removal residue of the resin layer remaining on the copper foil surface of the inner layer occurs. Connection failure with copper plating may occur. Therefore, more preferably, the inside of the hole is first treated in the gas phase to completely remove the residual layer of the resin, and then the inside of the hole is wet-treated, preferably by using ultrasonic waves.

As the gas phase treatment, generally known treatments can be used, and examples thereof include a plasma treatment and a low-pressure ultraviolet treatment. As the plasma, low-temperature plasma in which molecules are partially excited by a high-frequency power source and ionized is used. For this, high-speed processing using ion bombardment and gentle processing using radical species are generally used, and reactive gases and inert gases are used as processing gases. Oxygen is mainly used as the reactive gas, and the surface is scientifically treated. As the inert gas, an argon gas is mainly used. Using this argon gas or the like, physical surface treatment is performed. Physical treatment uses ion bombardment to clean the surface. The low ultraviolet ray is an ultraviolet ray having a short wavelength region, and irradiates a short wavelength region having a peak at 184.9 nm and 253.7 nm, and decomposes and removes the resin layer. After that, since the resin surface is often made hydrophobic, it is preferable to perform the wet treatment using ultrasonic waves in combination with the copper plating, particularly in the case of small-diameter holes. The wetting treatment is not particularly limited, but includes, for example, an aqueous solution of potassium permanganate, an aqueous solution for soft etching, and the like.

Electrical conduction can be obtained even if the inside of the hole is not necessarily filled with 50% by volume or more of copper plating. As the copper plating, generally known copper plating can be adopted. To form a pad on the top of the hole, a filling resin containing a metal filler is used. After filling the hole, the surface of the metal filler is exposed, and copper plating, nickel plating, and gold plating are performed thereon. Alternatively, a pad is formed so as to be connected to the hole, avoiding the hole.

[0033]

The present invention will be specifically described below with reference to examples and comparative examples. Unless otherwise specified, “parts” indicates parts by weight.

Example 1 900 parts of 2,2-bis (4-cyanatophenyl) propane,
100 parts of (maleimidophenyl) methane are melted at 150 ° C,
The mixture was reacted for 4 hours with stirring to obtain a prepolymer. This was dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. Add bisphenol A type epoxy resin (trade name: Epicoat 1001, Yuka Shell Epoxy Co., Ltd.)
) And 600 parts of a cresol novolac type epoxy resin (trade name: ESCN-220F, manufactured by Sumitomo Chemical Co., Ltd.) were uniformly mixed and dissolved. Further, as a catalyst, zinc octylate 0.4
Was added and dissolved and mixed. To this, 500 parts of an inorganic filler (trade name: calcined talc, manufactured by Nippon Talc Co., Ltd.) and 8 parts of a black pigment were added, followed by uniform stirring and mixing to obtain Varnish A. This varnish is impregnated with a glass woven fabric of 100 μm thickness and dried at 150 ° C.,
Gel time (at 170 ° C) 120 seconds, glass cloth content 56 weight
% Of prepreg (prepreg B) was prepared. Further, prepreg C having a glass content of 44% by weight was prepared.

3 μm electrolytic copper foil with a copper carrier having a thickness of 35 μm was placed above and below one prepreg B, and placed at 200 ° C.
Lamination molding was performed for 2 hours under a vacuum of 0 kgf / cm ² and 30 mmHg or less to obtain a double-sided copper-clad laminate D having an insulating layer thickness of 100 μm. Thereafter, the 35 μm copper sheet of the carrier was peeled off.

On the other hand, 800 parts of black copper oxide powder (average particle diameter: 0.8 μm) as a metal oxide powder was added to a varnish prepared by dissolving polyvinyl alcohol powder in water, and uniformly stirred and mixed.
This was coated on one side of a 50 μm-thick polyethylene terephthalate film so as to have a thickness of 30 μm.
After drying for 0 minutes, an auxiliary material E having a metal compound powder content of 45% by volume was prepared. Further, an aqueous solution of polyvinyl alcohol was applied on an aluminum foil having a thickness of 50 μm and dried to prepare a backup sheet F having a resin layer having a thickness of 25 μm.
On one side of the double-sided board, the auxiliary material E and the resin sheet of the backup sheet F are arranged so as to face the copper foil side, and laminated at 100 ° C., and a hole having a hole diameter of 100 μm is formed at the center of a 20 mm square within 6 mm.
Directly emit 44 shots in the corner with a direct carbon dioxide laser at 25 mJ / pulse for one shot, then at 20 mJ / pulse for 3 shots, drill through holes for 70 blocks of through holes, and coat the entire copper plating And the inside of the hole was filled with copper plating at 95% by volume. After removing the auxiliary material and the backup sheet, a circuit is formed on the back surface, a black copper oxide treatment layer is provided, the prepreg C is placed on the circuit, and an electrolytic copper foil having a thickness of 12 μm is arranged outside the circuit, and Similarly,
It was laminated and formed into a three-layer plate.

The three-layer plate was provided with a pore size of 100 μm as described above.
52 through holes were drilled. The copper foil layers on both sides are
The burrs on the copper foil around the hole were removed by P treatment, and the copper foil on the front and back surfaces was also dissolved to 4 μm. 9μm copper plating
A circuit was formed and black copper oxide treatment was similarly performed on the back surface, prepreg C was placed, 12 μm electrolytic copper foil was arranged, and a laminate was formed in the same manner to form a four-layer plate. Similarly, 48 through holes with a diameter of 100 μm are formed under the flip chip mounting portion, and a 150 μm through hole having a hole diameter of 150 μm is formed around the flip chip mounting portion of the four-layer plate so as to be connected to an inner copper foil. Opened. After placing it in a plasma machine and dissolving and removing the front and back layer copper foil to 3 μm by the SUEP method, at the same time dissolving and removing the copper foil burr generated on the inner layer copper foil, applying 10 μm of copper plating, Form a circuit (line / space = 50 / 50μm), solder ball land, etc. by the existing method, cover with a plating resist except for at least the flip chip mounting pad and solder ball pad, and apply nickel and gold plating To make a printed wiring board. On top of this, a flip chip of 6 mm square was mounted. The evaluation results are shown in Tables 1 and 2.

Example 2 A metal compound powder (57% by weight of SiO ₂ , Mg) was added to an aqueous resin solution prepared by dissolving a water-soluble polyester resin having a melting point of 58 ° C. in water.
O 43% by weight, average particle size: 0.4 μm), and uniformly stirred and mixed, and then applied to a 50 μm polyethylene terephthalate film so as to have a thickness of 20 μm.
After drying for 25 minutes, a film-shaped auxiliary material G having a metal compound content of 70% by volume was obtained. On the other hand, the prepreg B of Example 1 was replaced with 1
One sheet was used, and a 12 μm electrolytic copper foil was placed on the upper and lower sides and laminated and molded in the same manner to obtain a double-sided copper-clad laminate (FIG. 1 (1)). The above-mentioned drilling auxiliary material G and backup sheet F were arranged thereon, and were laminated with a roll of 100 ° C at a linear pressure of 2 kgf to form a coating film having good adhesion. Three shots were irradiated from above the auxiliary material G with an output of 35 mJ / pulse of a carbon dioxide gas laser, and 60 through holes were opened (FIG. 1 (2)).

The auxiliary material for the surface layer and the backup sheet were peeled off, subjected to a SUEP treatment, placed in a plasma apparatus, and treated for 10 minutes in an oxygen stream and further for 5 minutes in an argon stream, and then an aqueous potassium permanganate solution Performed wet treatment with ultrasonic waves at the same time, perform pulse copper plating in the same manner as in Example 1, fill the inside of the through hole with 95% by volume copper plating, and attach 10 μm thick copper plating on the front and back surfaces Was.

A circuit is formed on the lower surface (back surface), a black copper oxide treatment layer is provided, one prepreg C is placed outside the layer, and a 12 μm electrolytic copper foil is placed outside the prepreg C (FIG. 1).
(3)) Similarly, lamination molding was performed. The above-mentioned auxiliary material G and the backup sheet F were similarly laminated on the surface of the copper foil, and then irradiated with 4 shots at 40 mJ / pulse to form 40 through holes (FIG. 1 (5)). The copper foils on both sides were melted by SUEP to a thickness of 3 μm, copper plating was applied, the inside of the hole was filled with 87% by volume, and copper plating was applied to the front and back layers to a thickness of 10 μm. A circuit was formed on the lower surface. This was repeated to form a five-layer multilayer board (FIG. 1 (6)). A mechanical drill is used to connect a through hole with a hole diameter of 200μ around this flip chip mounting part to the circuit of each layer extending from the through hole formed in the flip chip mounting part to the surroundings. Product name: BT-S730B, Mitsubishi Gas Chemical Co., Ltd.
And heat-cured at 120 ° C. for 1 hour and further at 160 ° C. for 2 hours (FIG. 2 (7)). After mechanically polishing the front and back, SUEP
Dissolve the copper foil of the front and back layers to 3μm by the method, after desmearing,
Copper plating was applied to 10 μm. . Using this, a printed wiring board as in Example 1, mounted with a flip chip,
On the back surface, solder balls were bonded to the pads to form a plastic package (FIG. 2 (8)). Table 1 shows the evaluation results.
And Table 2.

Comparative Example 1 Using the double-sided copper-clad board of Example 1, a hole was similarly formed by a carbon dioxide gas laser without performing a surface treatment, but no hole was formed.

Comparative Example 2 Using the double-sided copper-clad board of Example 1, holes of 100 μm in diameter were formed in the copper foils on the front and back surfaces by etching, and the same number of shots as in Example 1 was performed using a carbon dioxide gas laser at an energy of 15 mJ / pulse. Holes were drilled, but glass fiber fluff was found on the hole walls, and the positions of the holes on the front and back were shifted by a maximum of 15 μm, and subsequent multilayering could not be performed.

Comparative Example 3 2,000 parts of an epoxy resin (trade name: Epikote 5045), 70 parts of dicyandiamide, and 2 parts of 2-ethylimidazole were dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide, and the mixture was stirred, mixed and uniformly dispersed to prepare Varnish H. I got This is impregnated with a 100 μm thick glass woven fabric, dried, and gelled.
140 seconds (at 170 ° C), prepreg I with 55% by weight of glass
It was created. In addition, a prepreg J having a glass content of 33% by weight was obtained by using a glass woven cloth having a thickness of 50 μm and gelling for 180 seconds. The prepreg I used one, place the electrolytic copper foil of 12μm on both ^{sides, 170 ℃, 20kgf / cm 2} , 30mmHg or less under vacuum
Lamination molding was performed for 2 hours to obtain a double-sided copper-clad laminate K. A circuit is formed on this copper clad laminate K, a black copper oxide treatment layer is provided,
Place one prepreg J on each of the upper and lower sides, and place 12 μm
The copper foil was placed and laminated and formed in the same manner to form a four-layer plate. A through hole having a hole diameter of 200 μm was formed around the periphery using a mechanical drill, and after desmearing, copper plating was applied to a thickness of 10 μm.
Using this, a printed wiring board was prepared, and a flip chip was mounted. The evaluation results are shown in Tables 1 and 2.

COMPARATIVE EXAMPLE 4 In the four-layer plate of Example 1 (FIG. 3A), the copper foil of the inner layer at the portion to be the through hole of the inner layer was removed in advance by etching so that the hole had a hole diameter of 100 μm. And a circuit is formed, and finally the same position on both sides is 100 μm in diameter.
The copper foil was removed by etching (FIG. 3 (2)), and a through-hole was formed with a carbon dioxide laser energy of 10 mJ / pulse (FIG. 3 (3)). After that, a desmear treatment is applied once without SUEP treatment, copper plating is applied 10 μm (Fig. 3 (4)), circuits are formed on the front and back, a printed wiring board is created in the same way, and a flip chip is mounted. did. The evaluation results are shown in Tables 1 and 2.

[0045]

[Table 1]

[0046]

[Table 2]

<Measurement method> 1) Misalignment of inner and outer hole positions on the front and back side Within a work size of 250 mm square, 70 blocks (63,000 total holes) were prepared with 900 holes / block having a hole diameter of 100 μm.
Drilling was performed with a carbon dioxide laser and a mechanical drill, and the maximum value of deviation between the front and back surfaces and the inner layer copper foil when 63,000 holes were drilled in one copper clad plate was shown. 2) Circuit pattern breakage and short circuit In Examples and Comparative Examples, a plate with no holes was created in the same way, a comb pattern of line / space = 50/50 μm was created, and then 200 patterns were etched with a magnifying glass. Was visually observed, and the total of the broken pattern and the short-circuited pattern was shown in the molecule. 3) Glass transition temperature Measured by the DMA method. 4) Through-hole heat cycle test Create a land with a diameter of 250 μm in each through-hole, connect 900 holes alternately to the front and back, and cycle one cycle at 260 ° C, solder, immersion for 30 seconds → room temperature for 5 minutes, 200 cycles And the maximum value of the rate of change of the resistance value was shown. 5) Cut of copper foil around land When a land with a diameter of 250 μm was formed around the holes on the front and back, chipping of the copper foil at the land was observed. 6) Insulation resistance value after pressure cooker process A comb-shaped pattern between terminals (line / space = 50 / 50μm) was created, and the prepregs used were placed on each of them, and laminated and molded at 121 ° C and 203kPa. After processing for a predetermined time at, perform post-processing at 25 ° C and 60% RH for 2 hours, and
VDC was applied to measure the insulation resistance between the terminals. 7) Migration resistance The test piece of the above 6) was applied at 85 ° C. and 85% RH at 50 VDC, and the insulation resistance between the terminals was measured. 8) Heat dissipation The package was bonded to the same motherboard printed wiring board with solder balls and used continuously for 1000 hours, and then the temperature of the package was measured.

[0048]

According to the present invention, in a method of manufacturing a flip-chip mounting printed wiring board having at least three copper foil layers, at least a pad of the flip-chip mounting portion is formed with a copper foil circuit of each inner layer and a hole diameter. Connect all the 25-300μm through-hole conductors, make the inner layer circuit a circuit that spreads around, connect the circuit that spreads around with a through-hole conductor that penetrates the front and back, and use this through-hole conductor for heat dissipation on the back and signal A method for manufacturing a high-density multilayer printed wiring board connected to lands connected to solder ball pads for propagation or the like is provided. According to the present invention, the pore diameter is 80 μm
More than 180μm or less through-hole, a metal oxide treatment layer or a chemical treatment layer is provided on the copper foil surface, or a melting point of 900 ° C. or more, and a binding energy of 300 kJ / mol or more metal compound powder, carbon powder, or metal powder. One or two or more kinds of drilling auxiliary materials containing 3 to 97 vol% are arranged, and from above, preferably
A carbon dioxide laser with an energy selected from 20 to 60 mJ / pulse is directly irradiated to make a through hole, and then at least 50% by volume of the inside of the hole is filled with copper plating. Placing the cloth base material prepreg and copper foil, drilling a through-hole for further through-hole after lamination molding, then dissolving part of the thickness of the surface layer copper foil in the thickness direction by etching with a chemical solution, at the same time around the hole periphery Also provided is a method for manufacturing a multilayer printed wiring board in which the generated copper foil burrs are dissolved and removed, copper plating is performed, and the above-described operations of lamination molding, through-hole formation, and copper plating are repeated as necessary. ADVANTAGE OF THE INVENTION According to the manufacturing method of this invention, the printed wiring board which is excellent in heat dissipation and hole connection reliability, and is high density is provided. ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the high density multilayer printed wiring board excellent in the connection reliability of surface layer copper foils is provided. According to the present invention, by using a polyfunctional cyanate resin composition as the thermosetting resin, the heat resistance is excellent, and the migration resistance and the electrical insulation after pressure are also excellent in reliability. A flip-chip printed wiring board is provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a multilayer board according to a second embodiment of the present invention.
It is process drawing of a three-layer board preparation, through-hole drilling (5), and pulse copper plating (6).

FIG. 2 is a diagram illustrating a five-layer plate of Example 2 in which through holes are formed by a gas laser after forming, through holes are formed in a peripheral portion by a mechanical drill, holes are filled with a resin, and pulse copper plating is performed (7).
And FIG. 10 is a process chart for producing a semiconductor plastic package (8).

FIG. 3 is a process diagram of drilling and copper plating of a multilayer board of Comparative Example 4 with a carbon dioxide gas laser (without SUEP).

[Explanation of symbols]

was filled with copper plating to a glass fabric substrate double-sided copper-clad laminate B foil burrs d ₁ generated in the through hole c through hole that is drilled in a carbon dioxide gas _{laser, d 2, d 3, d} 4 through holes Through hole e Pre-preg C f Copper foil g Through-hole formed in carbon fiber laser on three-layer plate h Burr generated i Filler resin j Flip-up k Flip chip bump l Solder ball pad m Solder ball n Plating resist o Four-layer plate p Through-hole part drilled by carbon dioxide laser q Displaced inner layer copper foil r Displaced through-hole copper plating

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/12 H05K 1/18 L H05K 1/18 B23K 101: 42 // B23K 101: 42 H01L 23/12 NF term (reference) 4E068 AF01 AF02 CF01 CF03 DA11 5E336 BB03 BC02 BC12 BC14 CC58 EE01 GG03 GG12 5E346 AA42 CC04 CC08 CC32 DD22 EE09 EE13 FF07 FF13 FF24 FF45 GG15 HH07 HH08 HH17 HH18

Claims (5)

[Claims] 1. A method for producing a flip-chip mounting glass cloth substrate high-density multilayer printed wiring board having at least three copper foil layers comprising the following steps: a. For through-holes of 180 μm or less, an auxiliary material for drilling is placed on the copper foil surface, and a carbon dioxide laser of sufficient energy to process the copper foil is directly irradiated to perform drilling (B). A step of dissolving and removing copper foil burrs generated around the hole at the same time as etching away a part of the copper foil; B. If necessary, a through hole having a hole diameter of 25 μm or more and less than 80 μm is excimer laser, YAG laser, and / or Alternatively, a through hole with a hole diameter of more than 180 μm and less than 300 μm is drilled with a mechanical drill, and then the surface and the inside of the hole are plated with copper (d ₁ ) .c. A circuit is formed on the lower surface side copper foil which is the inner layer of the double-sided copper clad board. form After that, the prepreg and the copper foil are arranged in this order on the circuit surface side and laminated and formed. D. The steps a, B and c are repeated as many times as necessary to obtain a multilayer board, and penetrate the front and back of the multilayer board. A step of electrically connecting the conductor (s) of the hole to the circuit (t) of each inner layer; e. A position where the solder ball pad (l) on the back surface of the multilayer board and the flip chip pad (u) on the front surface are provided. Drill through holes and, if necessary, remove part of the copper foil by etching and, at the same time, dissolve and remove copper foil burrs around the hole to form a circuit and pass flip chip pads and solder ball pads through the front and back of the multilayer board. Copper plating the holes and electrically conducting through the conductors; f. At least a flip chip mounting pad (u);
A process of applying precious metal plating to parts other than the solder ball pad part (l). 2. The method for manufacturing a high-density multilayer printed wiring board according to claim 1, wherein the conductor (s) of the hole passing through the front and back is electrically connected to the flip chip pad (u). . 3. The high-density multilayer print according to claim ₁ , wherein the holes (d ₁ , d ₂ , d ₃ ) reaching the respective inner layers are electrically connected to the flip chip pads (u). Manufacturing method of wiring board. 4. A metal oxide powder or a chemical treatment layer is provided on the surface of the copper foil before the irradiation with the carbon dioxide laser, or a metal compound powder having a melting point of 900 ° C. or more and a binding energy of 300 kJ / mol or more; 2. The method for producing a high-density multilayer printed wiring board according to claim 1, further comprising the step of arranging a resin composition containing 3 to 97% by volume of one or more of carbon powder and metal powder. 5. The method for manufacturing a high-density printed wiring board according to claim 1, wherein each through hole is filled with copper plating by 50% by volume or more.