JP2001007533A - Manufacture of ball grid array printed wiring board excellent in heat dissipating property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a wiring board to be improved in heat-resistant properties, electrical insulating properties, and profitability by a method wherein a truncated cone projection is formed on the backside of a both-sided metal plated laminate opposite to its chip mount surface, a prepreg and a metal foil are laminated on the front surface, and a hollow prepreg is stacked on the backside, and these components are thermocompressed into a laminated board. SOLUTION: Etching resist is applied on all the surface of a glass cloth-base both- sided metal plated laminated board, the backside is etched halfway, a truncated cone protrusion on the center surface of the board opposite to its other surface where a chip is mounted is left, and the board provided with a both-sided circuit d equipped with a center truncated cone protrusion e is formed by etching carried out from both its sides. A hollow prepreg g and a metal foil a are arranged on the backside, and a prepreg f and a metal foil a are arranged on the surface. These components are thermocompressed under vacuum into a both-sided metal plated multilayer board h. A part of the board other than a chip mounting part is covered with a protective resist and ground to enable a metal surface which serves as a chip mount to be exposed, and a chip is bonded for the formation of a semiconductor plastic package.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a novel printed circuit board for a ball grid array type semiconductor plastic package having at least one semiconductor chip mounted on the printed circuit board. The obtained printed wiring board is used for a relatively high wattage, multi-terminal, high-density semiconductor plastic package such as a microprocessor, a microcontroller, an ASIC, and a graphic. The present semiconductor plastic package is mounted on a motherboard printed wiring board using solder balls and used as an electronic device.

[0002]

2. Description of the Related Art Conventionally, as a semiconductor plastic package, a semiconductor chip such as a plastic ball grid array (P-BGA) or a plastic land grid array (P-LGA) is fixed on the upper surface of a plastic printed wiring board. It is connected to the conductor circuit formed on the upper surface of the printed wiring board by wire bonding, and on the lower surface of the printed wiring board, using a solder ball, a conductor pad for connecting to the motherboard printed wiring board is formed, and the front and back circuit conductors are plated 2. Description of the Related Art A semiconductor plastic package having a structure in which a semiconductor chip is sealed with a resin by connecting through a formed through hole is known. In the known structure, in order to diffuse heat generated from the semiconductor to the motherboard printed wiring board, plated through holes for heat diffusion are formed from the upper metal foil for fixing the semiconductor chip to the lower surface. Through the holes of the through-holes, moisture is absorbed by the resin adhesive containing silver powder used for fixing the semiconductor, and the interlayer blisters are heated by heating at the time of mounting on the motherboard and by heating at the time of removing the semiconductor components from the motherboard. There is a risk of this occurring, called the popcorn phenomenon. When this popcorn phenomenon occurs, the package often becomes unusable, and it is necessary to greatly improve this phenomenon. In addition, higher functionality and higher density of semiconductors mean more and more heat generation, and heat dissipation is insufficient with only through holes directly below the semiconductor chip for heat dissipation.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method of manufacturing a printed wiring board for a ball-grid array type semiconductor plastic package which solves the above problems.

[0004]

That is, according to the present invention, a semiconductor chip mounting surface is flat in a part of a printed wiring board in a thickness direction, and a back surface of a region substantially corresponding to the semiconductor chip mounting portion is provided. A metal plate having the same size as the printed wiring board, in which a plurality of metal truncated conical protrusions are connected to the copper foil on the back surface layer, is disposed around the surface of the printed wiring board.
Alternatively, a semiconductor chip is fixed on a metal plate that is more concave than a circuit including bonding pads in two stages, and the metal plate and a signal propagation circuit conductor on the surface of a printed wiring board are bonded with a thermosetting resin composition. Insulate, connect the circuit conductor and the semiconductor chip by wire bonding, and connect at least the circuit conductor on the surface of the printed wiring board and the circuit conductor or the package formed on the back surface of the printed wiring board to the outside with solder balls. In the method of manufacturing a printed wiring board used for a ball grid array type semiconductor plastic package having a structure in which circuit conductor pads formed for connection with through-hole conductors are used, a. A circuit is formed in a region other than the semiconductor chip mounting surface on the front surface, and a plurality of truncated cone-shaped protrusions and The process of forming a path, b. A glass cloth base thermosetting resin prepreg is placed on the surface, a metal foil is placed on it, and a glass cloth with a slightly larger area than the frusto-conical metal projection surface is cut on the back. Laminating a base material prepreg, placing a metal foil on the outside, laminating and molding under heat and pressure to create a double-sided metal-clad multilayer board, c. Through the parts other than the semiconductor chip mounting part and the truncated conical protrusion After forming a through hole for a hole and performing metal plating, at least the metal foil, the glass cloth base material and the resin layer on the surface where the semiconductor chip is to be mounted are removed, and the metal surface serving as the semiconductor chip mounting portion is removed. D. A solder board for forming at least a first-stage bonding pad and a circuit on the front surface, and connecting a heat-sinking solder ball to the metal foil having a frustoconical metal projection in contact with the surface metal foil on the rear surface. A ball grid comprising a step of forming pads and circuits, and a step of plating at least a semiconductor chip mounting portion, a wire bonding pad portion and a solder ball pad portion with a noble metal, in one or two stages. Provided is a method for manufacturing an array type printed wiring board.

Further, according to the present invention, in order to expose a second-stage bonding pad portion and a semiconductor chip mounting metal surface of the above-mentioned multilayer board, the metal foil of the surface layer of the multilayer board is removed, and then the heat of the surface layer is removed by sandblasting. After the curable resin composition and the glass cloth base material layer are ground to the second-stage bonding pad of the inner layer to expose the second-stage bonding pad, the second-stage bonding pad portion is covered, Provided is a method for manufacturing a printed wiring board for a ball grid array, which is formed by further cutting and removing a resin layer and a glass cloth base layer up to a metal plate by a sandblast method.

Using this printed wiring board, a semiconductor chip is bonded and fixed to the surface of the metal plate in the form of a cavity with a thermally conductive adhesive, and after wire bonding, the semiconductor chip is sealed with a sealing resin and then solder balls are formed on the back surface. Are melt-connected to produce a semiconductor plastic package. .

The obtained semiconductor plastic package has excellent thermal conductivity, does not absorb moisture from the lower surface of the semiconductor chip, and can greatly improve the heat resistance after moisture absorption, ie, the popcorn phenomenon. In addition, by using a polyfunctional cyanate ester composition as a thermosetting resin, it is excellent in electrical insulation after pressure cooker, migration resistance, etc., and is also suitable for mass production, and is economically improved. Further, a semiconductor plastic package having a novel structure can be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a semiconductor plastic package using a printed wiring board manufactured by the manufacturing method of the present invention will be described. In a part of the printed wiring board in the thickness direction, the surface on which the semiconductor chip is mounted is flat, and a plurality of truncated conical metal protrusions are connected to the surface metal foil on the back surface on the back surface almost corresponding to the semiconductor chip mounting portion. And a metal plate approximately the same size as the printed wiring board is arranged. A semiconductor chip is fixed on a metal plate at a position lower than a position of a circuit including one or two levels of bonding pads around a surface of a printed wiring board. The surface on which the semiconductor chip is mounted is lower than the surface of the signal propagation circuit on the surface of the printed wiring board. The semiconductor chip mounting portion of the metal plate is exposed, and at least one or more semiconductor chips are fixed to the exposed surface. The metal plate and the signal propagation circuit conductor on the surface of the printed wiring board are insulated by a thermosetting resin composition, and the circuit conductor and the semiconductor chip are connected by wire bonding. On the back side of the printed wiring board, a truncated conical protrusion from the metal plate is in contact with and connected to the surface metal foil, and a circuit conductor formed by connecting from this protrusion or the package is connected to the outside with a solder ball. Printed on a ball grid array type semiconductor plastic package having at least a semiconductor chip, a wire, and a bonding pad sealed with a resin by connecting the circuit conductor pad formed on the substrate with at least a surface circuit conductor and a through-hole conductor. It is a wiring board.

First, a circuit is formed on the surface of the glass cloth base material double-sided metal-clad laminate other than the portion on which the semiconductor chip is mounted, and a plurality of truncated conical metal protrusions and circuits are formed on the back surface substantially corresponding to the semiconductor chip mounting portion. Place a glass cloth base thermosetting resin prepreg on the surface that is the semiconductor chip mounting side,
A metal foil is placed thereon. On the back surface, a glass cloth base material prepreg having a hole slightly larger than the area of the truncated conical protrusion is overlapped, and a metal foil is arranged outside the prepreg. This is laminated under heat, pressure and preferably under vacuum to form a double-sided copper-clad multilayer board. Thereafter, through-holes for through holes are formed in portions other than the semiconductor chip mounting portion and the back surface of the truncated conical projection, and metal plating is performed. At least the metal foil, the glass cloth base material, and the resin layer on the surface where the semiconductor chip is mounted are removed to expose the metal surface to be the semiconductor chip mounting portion. First-stage bonding pads and circuits are formed on the surface. On the back surface, a solder ball pad and a circuit are formed to connect a heat radiating solder ball to a metal foil in which a truncated conical metal projection is in contact with a surface metal foil, and at least a semiconductor chip mounting portion, a wire bonding pad portion, and a solder ball pad portion are formed of a noble metal. By plating, a ball grid array type printed wiring board having one or two stages of wire bonding pads is manufactured.

The method of forming a cavity portion serving as a semiconductor chip mounting portion on this double-sided metal-clad multilayer board is not particularly limited, but preferably, a metal foil on the semiconductor chip mounting portion,
It is prepared by cutting and removing a base material and a thermosetting resin composition by a sandblast method. When the bonding pads are formed in two stages, first, the metal foil, the glass cloth base material, and the thermosetting resin composition on the semiconductor chip mounting portion and the region to be the second-stage bonding pad portion are subjected to sandblasting. After exposing the second-stage bonding pad by cutting, the second-stage bonding pad is protected by a protective film, a protective metal, etc., as necessary, so that it is not cut. The glass mounting member and the thermosetting resin composition are cut and removed from the chip mounting portion to reach the metal core, thereby exposing the metal plate serving as the semiconductor chip mounting portion. A first-stage bonding pad and a circuit are formed on the front surface, and a metal foil in contact with the truncated conical protrusion is formed on the back surface as a solder ball pad for connecting a solder ball for heat radiation and a circuit for connecting the solder ball pad.
A semiconductor chip, a wire bonding pad and a solder ball pad are covered with a plating resist, and nickel plating and gold plating are performed to produce a printed wiring board.

When a printed wiring board is prepared, circuits may be formed on the front and back sides before cutting by the sand blast method. In this case, the front and back circuits are covered with a protective resist or the like before the sand blast. In the case of precious metal plating, it is also possible to perform precious metal plating on the whole, and then to cover unnecessary portions with a permanent protection resist.

In a method of fixing a semiconductor chip on the upper surface of a conventionally known metal-core printed wiring board having a through hole, heat from the semiconductor chip is transferred to a heat-dissipating through hole immediately below, similarly to a conventional P-BGA package. There is no choice but to drop heat and dissipate heat, and the popcorn phenomenon cannot be improved. In the present invention, since the through hole is not formed below the semiconductor chip mounting surface, there is no moisture absorption from the back surface. Therefore, the popcorn phenomenon is extremely unlikely to occur, and a semiconductor plastic package having excellent heat dissipation properties is manufactured.

The method of forming the metal plate used in the present invention is not particularly limited, but for example, it can be manufactured by the following method. First, the metal foil in the range where the truncated cone-shaped metal protrusions on the back surface of the double-sided metal foil-clad laminate and in the range where the etching resist is left on the entire surface of the metal foil on the front surface and then etched to form the truncated cone-shaped metal protrusions in the shape of a truncated cone. Leave in shape. After peeling off the plating resist, the entire surface is again covered with the plating resist. On the front surface, if a second-stage bonding pad portion is required, a circuit on which the bonding pad is formed is formed. The etching resist is left as a small-diameter circle on the metal foil left in the trapezoidal shape where the is to be formed, and the other portions are etched so as to form a circuit, thereby forming a truncated conical projection and creating a circuit. In this case, the size of the truncated cone is not particularly limited, but preferably, the diameter of the trapezoidal upper part is
The diameter of the lower part should be 0.5 to 5 mm.

The surface of the double-sided metal-clad laminate having the truncated conical protrusions and the circuit formed on both sides is subjected to a surface treatment for improving adhesiveness and electrical insulation such as oxidation treatment, formation of fine irregularities, and formation of a film by a known method. Apply as needed. A heat conductive adhesive or solder may be attached to the truncated conical projection. The portion of the area on which the truncated cone-shaped protrusions are formed on the rear surface of the surface-treated rear surface, the glass cloth substrate prepreg that is cut and removed slightly larger than the area where the truncated cone-shaped protrusions are formed, after lamination molding, Arrange so as to be slightly lower than the height of the trapezoidal projection, and arrange the metal foil on the outside. An unprocessed glass cloth base prepreg is arranged on the surface on the semiconductor chip mounting side, and a copper foil is arranged outside thereof. This laminate is heated, pressurized, preferably laminated and formed under vacuum, and the tip of the truncated conical metal projection is cut into the metal foil of the surface layer, or is brought into strong contact and joined to form a single-sided metal-clad multilayer board. create.

In this case, a glass cloth base prepreg is preferable from the viewpoint of strength and the like, but an organic base prepreg, a coating resin and the like can be used as appropriate, and are not limited.

When a through hole for a through hole is formed in the obtained double-sided metal-clad multilayer board with a mechanical drill or a laser or the like, and a place for mounting a semiconductor chip is formed independently of a surrounding metal plate. In order to use the surrounding metal plate as a circuit, a hole is made so as to make partial contact with the metal, and through-hole plating is performed. When the metal plate on which the semiconductor chip is mounted and the surrounding metal plate are connected, holes are made so as not to contact the metal plate, and the whole is plated with copper. On the back surface, a ball pad is formed preferably at a location where the tip of the truncated cone-shaped projection is in contact with the surface metal foil or at such a location. In this case, the ball pad is connected to the metal foil on the metal protrusion by a circuit so that a circuit is formed by a generally known method.

The surface is coated with a semiconductor chip and a metal foil, a glass cloth base material and a thermosetting resin on the second-stage wire bonding pads by a counterbore processing, a laser, a sandblasting method or the like. Cutting is performed until the bonding pad is exposed. Thereafter, the semiconductor chip mounting portion is cut and removed to an inner metal plate to expose the metal plate, and a substrate having a cavity in the semiconductor chip mounting portion is created. In this case, the method of forming the second stage bonding pad portion is as follows.
The sand blast method is more preferable in terms of accuracy and the like.
After forming the circuit on the front and back, at least the portions other than the bonding pad portion and the solder ball pad portion on the back surface are covered with a plating resist, and nickel and gold plating is performed to produce a printed wiring board.

Thereafter, the semiconductor chip is bonded and fixed to the semiconductor chip mounting portion on the front surface with a thermally conductive adhesive, wire-bonded, and resin-sealed, and the back surface is melt-connected with a solder ball to form a semiconductor plastic package. Then, the solder ball pad portion on the back surface is joined to the motherboard printed wiring board with solder balls. The heat generated from the semiconductor chip is conducted from the semiconductor chip mounting portion, passes through the truncated metal conical protrusion on the opposite side of the metal core to the solder ball pad, and diffuses to the motherboard printed wiring board joined by the solder ball. .

Regarding the side surface of the metal plate, any of a shape embedded with the thermosetting resin composition and an exposed shape may be used, but the thermosetting resin composition is used from the viewpoint of preventing rusting and the like. It is more preferable that it is coated with.

In the case of a metal plate having a truncated cone-shaped projection on the back surface, the through-hole for conducting the front and back signal circuits is formed as follows.
When the semiconductor chip mounting portion at the center is connected to the surrounding metal foil, it is formed so as not to contact the metal plate. When the semiconductor chip mounting part and the surrounding metal plate are independent,
Since the surrounding metal plate can be used as a circuit, the circuit is formed in such a manner that the circuit is connected. Next, a metal layer inside the through hole is formed by electroless plating or electrolytic plating to form a plated through hole. As the sandblasting method, a generally known method can be used. Specifically, a dry type sand blast method, a shot blast method, a wet type wet blast method, and the like can be given.
The powder to be used is appropriately selected, but preferably a known powder such as silica sand or glass powder having a size of 20 μm or less is appropriately selected and used. The pressure is not particularly limited, but is generally 0.1 to 0.5.
Mpa.

After forming the front and back circuits, noble metal plating is formed on at least the surfaces of the semiconductor chip mounting portion, the bonding pad portion, and the solder ball pad portion to complete the printed wiring board. In this case, a portion that does not require noble metal plating is covered with a plating resist in advance. Or, after plating, if necessary, a known thermosetting resin composition, or a photoselective thermosetting resin composition, at least on the semiconductor chip mounting portion, the bonding pad portion, and the surface other than the solder ball bonding pad portion on the opposite surface. Form a film.

In the case of performing wire bonding, a semiconductor chip is fixed on a flat metal plate in an inner layer of the printed wiring board by using a heat conductive adhesive, and further, the semiconductor chip and one step of the printed wiring board circuit are fixed. The first and second bonding pads are connected by a wire bonding method, and at least the semiconductor chip, the bonding wires and the bonding pads are sealed with a known sealing resin.

A solder ball is connected to the solder ball connection conductor pad on the opposite side of the semiconductor chip to form a P-BGA, and the solder ball is superimposed on a circuit on a motherboard printed wiring board, and the ball is melt-connected by heat. Or, when mounting on the printed wiring board, the solder ball connection conductor pads formed on the motherboard printed wiring board surface
The solder ball conductive pad for P-LGA is connected to the solder ball by heating and melting the solder ball.

The metal foil used in the present invention is not particularly limited, but has a high elastic modulus and a high thermal conductivity, and preferably has a thickness of 5 to 200 μm.
Is used. Specifically, pure copper, oxygen-free copper, and alloys of Fe, Sn, P, Cr, Zr, .Zn and the like containing 95% by weight or more of copper are preferably used. Further, a metal foil or the like in which the surface of the alloy is plated with copper may be used.

The height of the metal frustoconical projection of the present invention is not particularly limited, but is preferably set to be 50 to 150 μm higher than the metal surface of the base. The thickness of the insulating layer such as a prepreg is set to be slightly lower than the height of the metal truncated conical projection after lamination molding, preferably lower by 5 to 10 μm.
After lamination molding, an insulating resin is filled between the truncated cone-shaped protrusion and the circuit, and the tip of the truncated cone-shaped protrusion is brought into contact with and joined to at least a part of the surface copper foil by pressure.

The range in which the metal truncated cone-shaped protrusions are formed is around the semiconductor chip area on the surface, and generally within 5 to 20 mm square. Preferably, a solder ball pad is formed avoiding a portion of the copper foil in contact with the metal projection on the back surface, and the solder ball pad and the circuit are connected to the metal foil on the projection so that the solder ball pad and the substrate are connected. To maintain the peel strength (ball shear strength) when pressure is applied to the solder ball from the side.

As the resin of the thermosetting resin composition used in the present invention, generally known thermosetting resins are used. Specifically, an epoxy resin, a polyfunctional cyanate ester resin, a polyfunctional maleimide-cyanate ester resin, a polyfunctional maleimide resin, an unsaturated group-containing polyphenylene ether resin, and the like, and one or more kinds Are used in combination. Polyfunctional cyanate ester resin compositions are preferred from the viewpoints of heat resistance, moisture resistance, 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 the 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.

As the polyimide resin, generally known ones can be used. Specific examples thereof 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 combination as appropriate 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-fluorinated ethylene copolymers; high molecular weight prepolymers or oligomers such as polycarbonate, polyphenylene ether, polysulfone, polyester, and polyphenylene sulfide; and polyurethane are exemplified and used as appropriate. Other known inorganic or organic fillers, dyes, pigments, thickeners, lubricants, defoamers, dispersants, leveling agents, photosensitizers, flame retardants, brighteners, polymerization inhibitors, thixotropic Various additives such as imparting agents are used in combination as needed. If necessary, the compound having a reactive group is appropriately blended with a curing agent and a catalyst.

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 economy, so that a known thermosetting catalyst is used for the thermosetting resin used. 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.

As the glass cloth base material used as the reinforcing base material of the prepreg, generally known woven cloths and nonwoven cloths are used, but woven cloths are preferable in view of strength. In particular,
Known glass fiber cloths, such as E glass, S glass, and D glass, are mentioned. These may be mixed.

As the metal foil, generally known ones can be used. Specifically, pure copper, a copper alloy, a nickel foil, or the like is used, and a copper foil having a thickness of 3 to 18 μm is preferably used.

The diameter of the clearance hole or the width of the slit hole formed in the metal plate is formed to be slightly larger than the diameter of the through hole for front / back conduction. Specifically, it is preferable that a distance of 50 μm or more between the through hole wall and the metal plate clearance hole or the slit hole wall is insulated by the thermosetting resin composition. The diameter of the through hole for front / back conduction is not particularly limited, but is preferably 50 to 300 μm.

When preparing a prepreg for a printed wiring board of the present invention, a base material is impregnated with a thermosetting resin composition and dried to obtain a semi-cured laminated material. The temperature for forming a semi-cured resin layer of the prepreg is generally 100 to 180 ° C. The time is 5 to 60 minutes, and is appropriately selected depending on the desired flow rate.

The method for producing the metal core of the present invention and the printed wiring board for a semiconductor plastic package using the metal core are not particularly limited, but for example, the following method (FIGS. 1 and 2). (1) Prepare a double-sided metal-clad laminate of a glass cloth base material with a thick metal plate on one side. (2) Attach an etching resist to the entire surface, and place an etching resist on the thick metal plate at the position where a frustoconical projection is to be formed. Leave the entire surface of the etching resist on the metal plate on the opposite side, etch the back halfway, and then trapezoidal projections on the opposite side of the central semiconductor chip mounting area
(c), leaving a metal plate lower than these protrusions around the periphery, removing the plating resist, and (3) again applying plating resist over the entire surface, forming a plurality of truncated conical protrusions on the trapezoidal protrusions With a double-sided circuit (d), a small diameter circular resist is left at the place where the circuit is to be formed, the resist is also left at the place where the circuit is formed, etched from both sides, and has a truncated conical projection (e) at the center of one side of the printed wiring board. A substrate is prepared, and a black copper oxide treatment is performed on the surface of the metal plate.
In this case, when the metal plate portion having the truncated cone-shaped metal projection is viewed from below, the semiconductor chip mounting portion having the truncated cone-shaped projection on the back surface in the center portion is partly formed with the metal plate on which the surrounding circuits are formed. Except for the shape (i) that is separated. In this case, it may not be separated. (4) On this back surface, place the glass cloth base material prepreg (g), which is slightly larger than the central metal protrusion area, and place the metal foil (a) on the outside, and cut out the front surface. A prepreg (f) is placed, and a metal foil (a) is placed on the outside of the prepreg (f). (6) A through hole for a through hole is made with a mechanical drill, and after desmearing, the whole is plated with copper to form circuits on the front and back (FIG. 2- (6)). (7) The surface of the semiconductor chip and the metal foil in the region of the second-stage bonding pad are removed by etching, and the surface of the glass cloth base material and the thermosetting from the surface side to the second-stage bonding pad (k) by sandblasting. (8) After the conductive resin composition is removed by cutting (FIG. 2- (7-1)), the area other than the semiconductor chip mounting portion is covered and protected with a protective resist, and then ground again by a sandblast method to a metal plate. Expose the flat metal surface (m) that will be the mounting part. Except for the exposed cavity-shaped metal surface, the first and second bonding pads, and the solder ball pads on the back surface, which are to be the semiconductor chip mounting parts on the front surface, are coated with plating resist (n), nickel plating, and gold plating To make a printed wiring board. The semiconductor chip (q) is bonded and fixed with a thermally conductive adhesive (r) to the semiconductor chip mounting portion (m) of the printed wiring board where the metal plate is exposed, and is connected with a bonding wire (p). After sealing with (o), the solder ball (s) is melted and adhered and fixed to a solder ball pad to obtain a semiconductor plastic package. 2
When the bonding pad (k) of the step is not formed, the metal surface (m) on which the semiconductor chip is mounted is directly ground by a sand blast method (FIG. 2- (7-2)). After that, a semiconductor plastic package is formed in the same manner as in (8).

[0040]

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.) was added, and uniformly mixed by stirring to obtain Varnish A. This varnish is impregnated with a 50 μm thick glass woven fabric, dried, and gelled (at 170 ° C.) 50 seconds, 170
A prepreg B in a semi-cured state having an insulating layer thickness of 137 μm was prepared so that the resin flow was 12 mm in 5 minutes at 20 ° C. and 20 kgf / cm ² .

On the other hand, using this prepreg B, 35
μm electrolytic copper foil, put 165 μm electrolytic copper foil on one side, 200
Laminate molding was performed at 20 ° C. and 20 kgf / cm ² for 2 hours to obtain a double-sided copper-clad laminate. An etching resist with a thickness of 25 μm is adhered to the entire surface, the etching resist is left entirely on the 35 μm copper foil side, the resist is left on the 165 μm side with an area that forms a frustoconical projection, and the etching is performed from both sides, and the surface is etched on one side. Shape projection
A double-sided copper-clad laminate having (c) was obtained [FIG. 1- (2)].
After removing the resist, a liquid etching resist of 25 μm is again adhered to the entire surface, and a 250 μm circular resist is applied on the diametrically opposite surface within the 15 mm square of the portion where the semiconductor chip is mounted in the center of the 50 mm square package area. The resist for forming a circuit is left around the surface, the surface is left for the second-stage bonding pad and the resist for forming the circuit of the surface layer, and the surface is etched from both sides. 225 frustoconical protrusions (e) having a bottom diameter of 612 μm and an upper diameter of 180 μm were formed, and a circuit (d) was formed around the front and back surfaces (FIG. 1- (3)). The copper foil serving as the semiconductor mounting portion having the truncated conical protrusion on the back surface has a shape (i) separated from the surrounding circuit-forming copper foil.

After the copper foil surface is subjected to black copper oxide treatment, one prepreg B (f) is disposed on the front surface side, and the truncated cone-shaped metal formed on the opposite surface of the semiconductor chip mounting portion is disposed on the back surface. Place one prepreg B (g) with a hole slightly larger than the projection (e), and place 18 μm electrolytic copper foil on the outside of the front and back.
(a) was arranged, laminated and molded in the same manner, and integrated to obtain a double-sided copper-clad multilayer board (h).

A through hole having a hole diameter of 0.25 mm was drilled by a mechanical drill, and after desmearing, the entire surface was plated with 20 μm copper by electroless and electrolytic copper plating.
Was formed. At the same time as forming the circuit on the front and back, the semiconductor chip mounting portion and the copper foil on the area to be the second-stage bonding pad are removed by etching, and then the semiconductor chip mounting portion and the portion to be the second-stage bonding wire portion are removed. The top is covered with a resist, the glass cloth base material and the thermosetting resin composition are cut off from the surface to the second-stage bonding wire by sandblasting, the resist is peeled off, and the semiconductor chip mounting portion is again protected with a protective resist. Cover everything except the top,
The glass cloth base material and the thermosetting resin composition (l) were cut and removed until the metal core was reached by sandblasting, the resist was peeled off, and sandblasting sand and the like on the surface were removed through a soft etching process. The solder ball pad on the back side is formed so as to be connected to the copper foil on the truncated cone, avoiding the truncated cone. A plating resist (n) was formed at portions other than the semiconductor chip mounting portion, the wire bonding portion, and the ball pad portion on the back surface, and nickel and gold plating were performed to complete a printed wiring board. After bonding a semiconductor chip (q) having a size of 13 mm square with a silver paste (r) on a flat inner metal core which is a semiconductor chip mounting portion on the surface, a wire bonding is performed on the first and second stages, and then The semiconductor chip (q), wires (p) and bonding pads (k) are resin-sealed using a silica-containing epoxy sealing liquid resin (o), and solder balls (s) are bonded to the back surface to form a semiconductor package. Created. This semiconductor plastic package was melt-bonded to an epoxy resin motherboard printed wiring board with solder balls. Table 1 shows the evaluation results.

Comparative Example 1 A semiconductor plastic package was produced in the same manner as in Example 1 except that the solder ball pad on the back surface was formed on a truncated cone-shaped metal projection. Table 1 shows the evaluation results.

Comparative Example 2 Two prepregs B of Example 1 were used, and 12 μm electrolytic copper foils were arranged on the upper and lower sides, and laminated and formed at 200 ° C., 20 kgf / cm ² , and a vacuum of 30 mmHg or less for 2 hours. A copper-clad laminate was obtained. A through hole having a hole diameter of 0.25 mmφ was drilled at a predetermined position, and copper plating was performed after desmear treatment. Circuits were formed on and under the plate by a known method, and were covered with a plating resist and then plated with nickel and gold. This has a through hole for heat dissipation at the place where the semiconductor chip is mounted, the semiconductor chip is bonded with a silver paste on this, and after wire bonding, resin sealing with a compound for epoxy stop as in Example 1 Then, solder balls were joined (FIG. 3). Similarly joined to the motherboard. Table 1 shows the evaluation results.

Comparative Example 3 300 parts of epoxy resin (trade name: Epicoat 5045, manufactured by Yuka Shell Epoxy Co., Ltd.) and epoxy resin (trade name: E
SCN220F, manufactured by Sumitomo Chemical Co., Ltd.) 700 parts, dicyandiamide 35 parts, 2-ethyl-4-methylimidazole 1 part are dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide, and this is dissolved in a 100 μm thick glass woven fabric. Impregnation and drying were performed to produce a no-flow prepreg (prepreg C) having a gelling time of 10 seconds and a resin flow of 98 μm, and a high-flow prepreg (prepreg D) having a gelling time of 150 seconds and a resin flow of 18 mm. Using two prepregs D, 190 ℃, 20kgf / cm2
Laminate molding was performed for 2 hours under a vacuum of 30 mmHg or less to prepare a double-sided copper-clad laminate. Thereafter, a printed wiring board was prepared in the same manner as in Comparative Example 1, the semiconductor chip mounting portion was cut out with a counterbore machine, and a copper plate having a thickness of 200 μm on the back surface was punched out of the no-flow prepreg D. heating,
The printed circuit board with a heat sink was similarly adhered under pressure to produce a printed wiring board. This slightly warped. A semiconductor chip was directly bonded to the heat sink with a silver paste, connected by wire bonding, and sealed with a liquid epoxy resin (FIG. 4).
Similarly, it was joined to a motherboard printed wiring board. Table 1 shows the evaluation results.

[0047]

[Table 1]

[0048]

[Table 2]

<Measurement Method> 1) Ball Shear Strength A solder ball was attached to a ball pad having a diameter of 0.55 mm, and the strength at the time of peeling by pressing from the side was measured. 2) Heat resistance after moisture absorption A) JEDEC STANDARD TEST METHOD A113-A LEVEL3: 30 ℃ ・ 60%
After the treatment with RH for a predetermined time, the presence or absence of an abnormality in the substrate after three cycles of reflow soldering at 220 ° C. was confirmed by cross-sectional observation and electrical check. 3) Heat resistance after moisture absorption B) JEDEC STANDARD TEST METHOD A113-A LEVEL2: 85 ℃ ・ 60%
After processing at RH for a predetermined time (Max. 168 hrs.), The presence or absence of abnormality in the substrate after three cycles of reflow soldering at 220 ° C. was confirmed by cross-sectional observation and electrical check. 4) Insulation resistance value after pressure cooker treatment A comb-shaped pattern between terminals (line / space = 70/70 μm) was created, and the prepregs used were placed on each of these patterns. After treatment for a predetermined time at atmospheric pressure, post-treatment was performed at 25 ° C. and 60% RH for 2 hours, and insulation resistance between terminals was measured 60 seconds after 500 VDC was applied. 5) Migration resistance The test piece of 4) was applied at 85 ° C. and 85% RH at 50 VDC, and the insulation resistance between the terminals was measured. 6) Glass transition temperature Measured by the DMA method. 7) 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.

[0050]

According to the present invention, the periphery of the double-sided copper-clad laminate of glass cloth substrate is etched away to leave a part of the metal foil on at least one side to form a convex portion, and further, the area of the surface on which the semiconductor is mounted In addition to forming a circuit, a plurality of truncated cone-shaped metal protrusions and circuits are formed on the surface directly opposite to the semiconductor chip mounting surface, a glass cloth base material prepreg is placed on the surface, and a metal foil is disposed thereon, and the opposite surface is provided. The glass cloth base prepreg, which is slightly larger than the area of the truncated cone, is layered, and a metal foil is placed on the outside of the prepreg, heated, pressed, and laminated under vacuum to create a double-sided metal-clad laminate I do.

Thereafter, through-holes for through holes are formed in portions other than the semiconductor chip mounting portion and on the opposite surface other than the truncated conical protrusions, metal plating is performed after desmearing, and circuits are formed on the front and back surfaces, and at the same time, the semiconductor chip mounting on the front surface is performed. Metal foil on the surface to be the part and the second-stage bonding pad part,
The glass cloth base material and the thermosetting resin composition are ground and removed by sandblasting or the like until the second-stage bonding pad is exposed, and then the second-stage bonding pad portion is protected with a protective metal sheet, a resist, or the like. After protection, the metal core is again cut and removed by sandblasting to expose the metal core, and at least parts other than the semiconductor chip mounting part, wire bonding part and ball pad part are covered with a plating resist, and nickel plating and gold plating are performed. By applying to the printed wiring board, the adhesive strength with the solder ball is excellent, and there is no moisture absorption from the lower surface of the semiconductor chip.
The heat resistance after moisture absorption, that is, the popcorn phenomenon, can be significantly improved, and by using a polyfunctional cyanate resin composition as the resin, it is excellent in electrical insulation and migration resistance after pressure cooker treatment, as well as mass production Thus, a printed wiring board for a semiconductor plastic package having a novel structure, which is suitable for and has improved economic efficiency, can be manufactured.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a printed wiring board used for a ball grid array type semiconductor plastic package containing a metal core of Example 1.

FIG. 2 is a manufacturing process diagram of a printed wiring board used for a ball grid array type semiconductor plastic package containing a metal core of Example 1.

FIG. 3 is a manufacturing process diagram of a semiconductor plastic package of Comparative Example 2.

FIG. 4 is a manufacturing process diagram of a semiconductor plastic package of Comparative Example 3.

[Explanation of symbols]

a Metal foil a 'Metal plate b Glass cloth base thermosetting resin layer c Trapezoidal projection d Front and back circuit e Frustum conical projection f Prepreg B g Prepreg B with hollowed out truncated cone projection h h Double-sided copper-clad multilayer board i Semiconductor Figure showing the chip mounting part and surrounding circuits separated j Metal plated through hole k Second bonding pad l Glass cloth substrate and resin layer on semiconductor chip mounting metal part m Semiconductor chip mounting metal exposed part n Plating resist o Sealing resin p Bonding wire q Semiconductor chip r Thermal conductive adhesive s Solder ball t Prepreg Bu u Heat dissipation through hole v Prepreg Cw Copper plate x First-stage bonding pad

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsuji Kobayashi F-term (reference) 5E346 AA42 CC04 CC08 CC09 CC32 CC37 CC38 CC39 CC41 at 6-1-1, Shinjuku, Katsushika-ku, Tokyo, Tokyo, Japan DD23 EE09 EE13 EE18 FF04 FF07 FF09 FF10 FF13 FF19 FF24 FF37 GG15 GG17 GG28 HH17 HH18

Claims (4)

[Claims] 1. A surface on which a semiconductor chip is mounted is flat in a part of a printed wiring board in a thickness direction, and a plurality of metal truncated cone-shaped protrusions are provided on a back surface of a region substantially corresponding to the semiconductor chip mounting portion on a back surface layer. A metal plate connected to a copper foil and having substantially the same size as the printed wiring board is arranged, and is recessed from a circuit including bonding pads in one or two steps around the surface of the printed wiring board. A semiconductor chip is fixed on a metal plate, the metal plate and the signal propagation circuit conductor on the surface of the printed wiring board are insulated with a thermosetting resin composition, and the circuit conductor and the semiconductor chip are connected by wire bonding, At least the circuit conductor on the surface of the printed wiring board and a circuit conductor formed on the back surface of the printed wiring board or a circuit conductor pad formed for connecting the package to the outside with solder balls. In a method of manufacturing a printed wiring board used for a ball grid array type semiconductor plastic package having a structure connected by through-hole conductors, a. Forming and forming a plurality of truncated cone-shaped protrusions and circuits on the back surface of the semiconductor chip mounting surface; b. Placing a glass cloth base thermosetting resin prepreg on the front surface, placing metal foil on it, and placing the back surface A process to create a double-sided metal-clad multi-layer board by laminating a glass cloth base prepreg that has a slightly larger area than the truncated conical metal projection surface, placing a metal foil on the outside, and laminating and molding under heat and pressure C. Form through holes for through holes at locations other than the semiconductor chip mounting part and the truncated cone projection, apply metal plating, and mount the semiconductor chip on at least the surface. Removing the metal foil, glass cloth base material, and resin layer on the portion to be exposed to expose a metal surface to be a semiconductor chip mounting portion, d. Forming at least a first-stage bonding pad and a circuit on the surface A solder ball pad for connecting a heat radiating solder ball to a metal foil having a truncated conical metal projection in contact with a surface metal foil is formed on a rear surface, a circuit is formed, and at least a semiconductor chip mounting portion, a wire bonding pad portion, and a solder ball pad are formed. A method of manufacturing a ball grid array type printed wiring board, wherein a wire bonding pad comprising a step of plating a portion with a noble metal is formed in one or two stages. 2. The method for manufacturing a ball grid array type printed wiring board according to claim 1, wherein the metal plate of the semiconductor chip mounting portion and a conductor circuit around the metal plate are independently formed. 3. A method for exposing a second-stage bonding pad portion and a semiconductor chip mounting metal surface of the multilayer board, removing a metal foil on a surface layer of the multilayer board, and then using a sand blast method to form a thermosetting resin on the surface layer. After grinding the composition and the glass cloth base material layer to the inner layer second bonding pad, exposing the second bonding pad, the second bonding pad portion is covered, and is sandblasted. 3. The method for manufacturing a printed circuit board for a ball grid array according to claim 1, further comprising cutting and removing the resin layer and the glass cloth base material layer up to the metal plate. 4. The ball grid array according to claim 1, wherein the thermosetting resin is a thermosetting resin composition containing a polyfunctional cyanate ester and the cyanate ester prepolymer as essential components. Manufacturing method of die printed wiring board.