JP2000260901A - Multilayer printed wiring board for metal core semiconductor plastic package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multiplayer printed wiring board for semiconductor plastic package excellent in connectivity between inner metal core and outer metal foil, heat dissipation properties, heat resistance after moisture absorption, and the like. SOLUTION: In a cavity semiconductor plastic package of ball grid array employing a metal core having a plurality of truncated conical metallic protrusions 1 on the surface and rear, prepreg having scooped protrusions are arranged on the opposite sides of the metal core and hot pressed and then a circuit is formed only on the surface. It is then treated chemically and a prepreg (g) having a scooped semiconductor chip mounting part is arranged again on the surface. Subsequently, through holes (i) and blind holes are made, immediate upper part of the metal foil for mounting a semiconductor is cut off after desmearing, flow-out resin is removed by sandblasting, circuits are formed on the surface and rear, plating resist is applied and followed by noble metal plating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel multilayer printed wiring board for a semiconductor plastic package containing a metal core, wherein at least one semiconductor chip is mounted on a small printed wiring 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 the lower surface of the printed wiring board is formed with conductor pads for connection with the motherboard printed wiring board using solder balls, 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, a plated heat diffusion through hole is formed from the upper metal foil for fixing the semiconductor chip to the lower surface in order to diffuse the heat generated from the semiconductor to the motherboard printed wiring board. Through the hole of the through hole, moisture is absorbed by the resin adhesive containing silver powder used for fixing the semiconductor,
There is a danger that interlayer blisters may occur due to heating during mounting on the motherboard and heating when removing the semiconductor component from the motherboard, which is called a popcorn phenomenon. When this popcorn phenomenon occurs,
Packages are often unusable, and this phenomenon needs to be greatly improved. In addition, higher functionality and higher density of semiconductors mean more and more heat generation, and heat dissipation is becoming insufficient only with through holes provided directly below the semiconductor chip for heat dissipation.

[0003]

SUMMARY OF THE INVENTION The present invention provides a multi-layer printed wiring board for a semiconductor plastic package containing a metal core, in which the above problems are improved.

[0004]

That is, according to the present invention, a metal plate having substantially the same size as a printed wiring board is disposed in a part of the printed wiring board in a thickness direction, and at least one metal plate is provided on one surface of the printed wiring board. The semiconductor chips are fixed with a heat conductive adhesive, the metal plate and the signal transmission 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 bonded by wire bonding. Connecting the circuit conductor on at least the surface of the printed wiring board and a circuit conductor formed on the opposite surface of the printed wiring board or a circuit conductor pad formed for connecting the package to the outside with solder balls, And a through-hole conductor insulated with a thermosetting resin composition, and at least a semiconductor chip, a semiconductor chip, a wire, and a bonding pad are resin-sealed. In a printed wiring board for a semiconductor plastic package, a plurality of truncated cone-shaped metal projections on the front and back, or the metal projections to which a heat conductive adhesive or solder is attached, and clearance holes or slit holes for forming front and back conduction holes. A prepreg, resin sheet, or application of a semi-cured thermosetting resin composition, which is formed by chemically treating the formed metal plate and cutting the surface slightly larger than the area for mounting the semiconductor chip on the metal protrusions on the front and back surfaces. After disposing the applied resin layer, disposing the metal foil on the outside, laminating and integrating under heat and pressure, preferably under vacuum, forming a circuit on the surface, chemically treating the metal foil surface After that, a prepreg, resin sheet, and coating resin layer, which are cut slightly larger than the semiconductor chip area, are placed on the outside, and metal foil and single-sided metal foil are placed on the outside. Laminate board, or forming a circuit on one side, place a double-sided board or multilayer board subjected to chemical treatment, with the circuit facing the resin side, under heat, under pressure, preferably under vacuum, laminate molding Drill through holes for blind holes and blind holes on the obtained double-sided board with metal core, apply metal plating after desmear treatment, form circuits on the front and back, and cut off the surface on the metal foil on the semiconductor chip mounting part on the surface Then, at least on the metal foil for mounting the semiconductor chip on the front surface, the bonding pad, except for the ball pad on the back surface, coating with a plating resist, nickel plating,
The present invention relates to a multilayer printed wiring board for a semiconductor plastic package having a metal core obtained by applying gold plating. The resulting semiconductor plastic package has excellent electrical and thermal conductivity, excellent adhesion of the solder balls to the substrate, no moisture absorption from the lower surface of the semiconductor chip, and can greatly improve the heat resistance after moisture absorption, that is, the popcorn phenomenon. At the same time, by using a polyfunctional cyanate composition as a thermosetting resin, it is excellent in electrical insulation after pressure cooker, migration resistance, etc., and in addition, suitable for mass production, improving economic efficiency. Thus, a semiconductor plastic package having a novel structure can be obtained, and the present invention has been completed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A semiconductor plastic package produced by using a double-sided multilayer metal foil clad board manufactured according to the present invention has a metal plate substantially the same size as a printed wiring board arranged in a part of the thickness direction. At least one semiconductor chip is fixed to one surface of the printed wiring board with a heat conductive adhesive, and the metal plate and the signal transmission circuit conductor on the surface of the printed wiring board are insulated with a thermosetting resin composition. Then, the circuit conductor and the semiconductor chip are connected by wire bonding, and at least the circuit conductor on the surface of the printed wiring board and the circuit conductor or the package formed on the opposite surface of the printed wiring board are connected to the outside with solder balls. The circuit conductor pad formed for this purpose is connected with a metal plate and a through-hole conductor insulated with a resin composition, and at least a semiconductor chip, a wire, and a bonding In a semiconductor plastic package having a structure in which a pad is resin-sealed, a metal core having a plurality of truncated cone-shaped metal projections on the front and back, or a metal core having a thermally conductive adhesive or solder adhered thereon. A semi-cured prepreg in which a clearance hole or slit hole is formed in a part other than the above, and the part is cut off slightly larger than the area where the semiconductor chip is mounted on the front and back surfaces where the truncated conical metal projection of this metal core exists , Resin sheet,
Or place a coating resin layer, put a metal foil on the outside,
After laminating under heating, pressurizing, preferably under vacuum and integrating, a circuit is formed on the surface, the metal foil surface is chemically treated, and outside, a little more than the area of the place where the semiconductor chip is mounted. A semi-cured prepreg, resin sheet, or coated resin layer that is oversized is placed, and a metal foil, a single-sided metal foil-clad laminate, or a circuit is formed on one side, and both sides of the metal foil surface are chemically treated. Board or multilayer board,
The circuit side faces inward and is laminated and molded to create a double-sided metal foil-clad multilayer board. After this, a through hole for through hole is made with a mechanical drill, laser, etc. so that it does not contact the metal plate of the inner layer, further a blind hole is made, metal plating is applied after desmear treatment, and a circuit is formed by a standard method. A portion of the surface of the metal foil on which the semiconductor chip is mounted is cut off by a known method, and at least the surface semiconductor chip, the wire bonding pad, and the ball pad on the rear surface are covered with a plating resist, and nickel plating and gold plating are performed. To form a printed wiring board. A semiconductor chip is fixed on the metal foil in contact with the truncated cone-shaped metal protrusion on the surface with a heat conductive adhesive, connected to the surrounding circuit conductor by wire bonding, and at least the semiconductor chip, bonding wires and bonding pads are sealed with resin. Stop the solder ball on the solder ball pad connected to the precious metal plated metal foil on the frustum-shaped projection on the back side, and make it a form that is joined to the motherboard printed wiring board, and the front and back circuit conductors and the plated for conduction The through hole has a structure insulated by a thermosetting resin composition.

In a known method of fixing a semiconductor chip on the upper surface of a metal-core printed wiring board having a through hole, heat from the semiconductor chip is dropped to a heat dissipation through hole immediately below, similarly to a conventional P-BGA package. Heat must be dissipated and the popcorn phenomenon cannot be improved. The present invention forms a truncated-cone-shaped metal projection on the front and back surfaces on both surfaces of a metal flat plate serving as a metal core by a known etching method or the like in advance, drills a clearance hole or a slit hole, and increases the surface area of the semiconductor chip on both surfaces. A semi-cured prepreg with a slightly larger hole, a resin sheet or a coating resin layer is placed so that it is slightly lower than the height of the metal projections after lamination molding, and a metal foil is placed on the outside, heating, The laminate is molded under pressure, preferably under vacuum, and integrated so that the outer metal foil portion and the tip of the truncated cone-shaped protrusion are connected to produce a double-sided metal foil clad board with an inner metal core. After using this to form a circuit on one side and subject it to chemical treatment,
A semi-cured prepreg, resin sheet, or resin layer with a hole slightly larger than the semiconductor chip
Preferably placed in a low-flow or no-flow, a metal foil, a single-sided metal foil-clad laminate, or a circuit formed on one side, and a chemically treated double-sided board or double-sided metal foil-clad multilayer board Are arranged so that the circuit side faces inward, and similarly laminated and formed into a multilayer board. After forming a circuit on both sides, a metal foil directly above the metal foil with which the frusto-conical projection tip is in contact, and / or a base material such as a router or sandblast for mounting the semiconductor chip of this plate is known. Cut off by the method, and then, if necessary, the resin that has flowed out onto the metal foil surface on which the semiconductor chip is mounted, at least to the extent that the semiconductor chip can be mounted, preferably such that the metal foil surface is exposed to an area equal to or larger than the semiconductor chip, Preferably, it is processed by a sand blast method, and a circuit is formed by an ordinary method to obtain a cavity-type multilayer printed wiring board.

The method of forming the metal core is not particularly limited. For example, first, about half of the thickness of the metal plate is etched away from both sides except for the area where the metal protrusion is formed on the metal plate. After removing the etching resist, cover the entire surface again with a liquid etching resist, leave the etching resist in a circular shape on the front and rear surfaces where the truncated cone-shaped metal protrusions are formed, and at the same time, etch the resist resist where clearance holes or slit holes are formed. Is removed and etched from both sides with an etching solution to form a truncated conical projection on the front and back surfaces, and at the same time, a metal core is formed by a method of forming a clearance hole or a slit hole.

The surface of the metal plate on which the truncated cone-shaped projections and the clearance holes or slit holes are formed is subjected to oxidation treatment, formation of fine unevenness, formation of a film, and other surface treatments for improving adhesion and electrical insulation by known methods. Is applied as needed. A heat conductive adhesive or solder may be attached to the truncated conical projection. A prepreg, a resin sheet, or a coating resin layer, which is slightly larger than the area of the shape, is slightly lower than the height of the trapezoidal protrusion after lamination molding in the truncated conical protrusions on the front and back surfaces after the surface treatment. Arranged in such a way, placing a metal foil on the outside, heating, pressurizing, preferably laminating under vacuum, filling the clearance hole or slit hole with thermosetting resin,
The tip of the truncated-cone-shaped metal projection is cut into the metal foil on the surface layer and joined. A circuit is formed on the side on which the semiconductor chip is mounted, a metal surface treatment is performed, and a prepreg, a resin sheet, or a coating resin layer cut out so as to be slightly larger than the semiconductor chip area is arranged thereon. Put a metal foil, a single-sided metal foil-clad laminate, or a double-sided metal foil-clad multilayer board or a double-sided metal foil-clad multilayer board that has been subjected to chemical treatment by forming a circuit on one side, with the circuit side facing inward, and It was laminated and formed into a multilayer board. After forming a through hole for through hole, further drilling a blind hole, desmearing, metal plating, forming a circuit, mounting a semiconductor chip on this surface, a metal frustum of the frusto-conical metal protrusion contacting Cut off the upper metal foil and / or base material with a router, etc.
If the resin flows out and remains on the metal foil on which the semiconductor chip is mounted, the resin is preferably removed by sandblasting.

In the obtained double-sided metal foil-clad multilayer board, a through hole is formed in a place where a clearance hole or a slit hole is formed so as not to be in contact with a metal core by a known method such as a mechanical drill or a laser. Metal plating. A portion where the tip of the truncated cone-shaped protrusion on the surface is in contact with the surface metal foil is left as a semiconductor chip mounting portion. On the back surface, a ball pad is formed so as to avoid a portion which is in contact with the metal protrusion or the portion. 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. At least the semiconductor chip mounting portion of the surface layer, the bonding pad portion, and the solder ball pad portion on the back surface are covered with a plating resist,
Nickel and gold plating are applied to create a printed wiring board. Thereafter, the semiconductor chip is bonded and fixed to the semiconductor chip mounting portion on the surface with a heat conductive adhesive, wire-bonded, and resin-sealed to obtain a semiconductor plastic package. The solder ball pad on the back surface may be formed on a truncated conical projection, but in order to improve the adhesive strength of the ball, a circuit is formed on the truncated conical projection and connected to this circuit, except for the upper part of the projection. It is preferable to create it. Then, the solder ball pads on the back surface are joined to the motherboard printed wiring board by melting the solder balls. The heat generated from the semiconductor chip is conducted from the semiconductor chip mounting portion, passes through the truncated conical projection of the metal core, and is transmitted to the metal core,
Conduction is transmitted to the solder ball pad through the metal truncated conical protrusion on the opposite surface, and diffuses to the motherboard printed wiring board joined by the solder ball.

The side surface of the metal plate may be coated or exposed with the thermosetting resin composition, but may be formed in any shape. It is more preferable that it is coated with.

The through hole for the front and back signal circuits is formed substantially at the center of the metal plate clearance hole or slit hole in which the resin is embedded so as not to contact the metal plate. Next, a metal layer inside the through hole is formed by electroless plating or electrolytic plating to form a plated through hole.

After forming the front and back circuits, a noble metal plating is formed on at least the surface of the wire bonding pad 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 a semiconductor chip mounting portion, a bonding pad, a coating on a surface other than the solder ball bonding pad on the opposite surface. Form.

[0013] A semiconductor chip is fixed on a surface metal foil in contact with the inner layer frustum-shaped metal core of the printed wiring board using a thermally conductive adhesive, and further, a bonding pad of the semiconductor chip and a printed wiring board circuit is provided. 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 connecting 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. When making a P-LGA without attaching solder balls to the package and mounting it on the motherboard printed wiring board, the solder ball connection conductor pad formed on the motherboard printed wiring board surface and the solder ball conductor for the P-LGA The pad and
The solder balls are connected by heating and melting.

Although the metal plate used in the present invention is not particularly limited, a metal plate having a high elastic modulus, a high thermal conductivity and a thickness of 150 to 500 μm is suitable. Specifically, pure copper, oxygen-free copper, and others,
An alloy of 95% by weight or more of copper with Fe, Sn, P, Cr, Zr, .Zn, or the like is preferably used. Further, a metal plate or the like in which the surface of the alloy is plated with copper may be used.

The height of the metal truncated conical protrusion of the present invention is not particularly limited, but is preferably 50 to 150 μm. Also, the thickness of the insulating layer such as prepreg, resin sheet, etc., after lamination molding,
Slightly lower than the height of the metal frustum, preferably 5 to 1
After lamination molding, resin is filled between the truncated cone-shaped protrusions and the clearance holes or slit holes, and the tip of the truncated cone-shaped protrusion contacts and joins at least a part of the surface metal foil by pressure after lamination molding. Let it. Also, in this case,
A generally known heat-conductive adhesive such as lead-free solder, silver paste, or copper paste may be adhered to the truncated cone-shaped protrusion, and the protrusion may be bonded to the outer metal foil.
The size of the truncated cone is not particularly limited,
Generally, the diameter at the bottom is 0.5-5 mm and the diameter at the top is 0-1 mm.

The sand blasting method is a method in which fine or particulate sand is sprayed at a high speed in a wet or dry manner, and the resin or the like on the surface is shaved and removed. As the particles, generally known powders such as glass beads or silicon carbide having a size of about 20 to 40 μm are used.

The range in which the metal truncated cone-shaped protrusions are formed is around the semiconductor chip area, and generally within 5 to 20 mm square.
It should be present at the semiconductor chip fixing location and the opposite surface. Preferably, a ball pad is formed avoiding a portion of the metal foil in contact with the metal projection on the back surface, and the ball pad and the circuit are connected to the metal foil on the projection so that the ball pad is bonded to the substrate. Peel strength (ball shear strength) when pressure is applied to the ball from the side while maintaining strength
To be able to hold.

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 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.

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 economical 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.

As the reinforcing base material of the prepreg, generally known inorganic or organic woven or nonwoven fabric is used. Specific examples include known glass fiber cloths such as E glass, S glass, and D glass, wholly aromatic polyamide fiber cloths, and liquid crystal polyester fiber cloths. These may be mixed. Alternatively, a thermosetting resin composition applied to the front and back of a film such as a polyimide film and heated to a semi-cured state can be used.

As the outermost metal foil, generally known ones can be used. Preferably, a copper foil, a nickel foil or the like having a thickness of 3 to 18 μm is used. The inner layer copper foil is preferably 18-70 μm thick
Use

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 substrate is impregnated with a thermosetting resin composition and dried to obtain a semi-cured laminated material. Further, a resin sheet in a semi-cured state without using a base material can be used. Paints can also be used. The temperature for forming a semi-cured resin layer such as a 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 printed wiring board for a semiconductor plastic package having a metal core according to the present invention is not particularly limited. For example, the following method (FIGS. 1 and 2) is used. (1) The entire surface of the metal plate serving as the metal core is coated with a liquid etching resist, and the solvent is removed by heating.After that, the semiconductor chip is fixed, and the entire surface of the resist which forms the frustum of the metal cone on the opposite surface is left. And the others are etched by about 1/2 of the thickness. (2) After removing the etching resist, (3) Cover the entire surface again with the liquid etching resist, leave the resist in a circular shape in the part to be left as a truncated conical projection on the surface of the convex trapezoid, and in addition, a clearance hole part (4) Etching is performed with an etching solution from above and below by etching to form a truncated cone-shaped projection on the front and back surfaces and simultaneously form a clearance hole. (5) A prepreg (FIG. 1-c) having a hole slightly larger than the area of the metal protrusion is arranged on the front and back sides, and a copper foil (FIG. 1-a) is arranged outside the prepreg. In this case, the hole does not necessarily have to be large, as shown in FIG. 1- (2), but may partially overlap the frustoconical projection at the end, but a larger hole is preferable. (6) Lamination molding is performed under heat, pressure, and vacuum, and resin is flowed into and filled between the metal truncated conical protrusions and the clearance holes, and integrated (FIG. 1- (4)). (7) After forming a circuit on the surface and subjecting it to a chemical treatment, a semi-cured prepreg, resin sheet or coating is formed on the part where the semiconductor chip is to be mounted again, with a hole slightly larger than its area. A resin layer is arranged, and a metal foil, a single-sided metal foil-clad laminate, or a double-sided board or a multilayer board on which a circuit is formed and a chemical treatment is performed on one side is arranged so that the circuit side faces inward (see FIG. 2- (5)), and laminate molding is performed in the same manner (FIG. 2- (6)). (8) Make a hole in the clearance hole with a mechanical drill so as not to contact the metal core, (9) Copper plating the whole after desmearing, (10) Form a circuit on the surface, and mount the semiconductor chip The metal foil and / or base material directly above the metal foil are cut and removed by a router. (11) If the resin is flowing out onto the metal foil at the semiconductor chip mounting location during lamination molding (FIG. 2-j), The resin on the metal foil surface is removed by sand blasting, etc. (12) Cover with a plating resist except for the metal foil part, bonding pad, and solder ball pad part on the back surface that will be the semiconductor chip mounting part, and nickel plating Then, a printed wiring board is prepared by applying gold plating. (13) The semiconductor chip is bonded and fixed on the surface with silver paste,
After the wire bonding, at least the semiconductor chip, the wires, and the wire bonding pads are resin-sealed. On the back surface, a solder ball is melt-bonded to a pad to form a semiconductor plastic package.

[0032]

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 BST # 200, manufactured by Nippon Talc Co., Ltd.) was added, followed by uniform stirring and mixing to obtain Varnish A. This varnish is 100μ thick
m glass woven cloth, dried, gel time (at 170 ℃)
50 seconds, 170 ° C., 20 kgf / cm ² , prepreg B in a semi-cured state having a thickness of 144 μm of a semi-cured resin having a thickness of 144 μm, a resin flow of 0.5 mm, a gelation time of 13 seconds, and a resin flow of 10 mm in 5 minutes. Thickness 1
Prepreg C of 45 μm was obtained. On the other hand, an alloy plate of Cu: 99.9%, Fe: 0.07%, P: 0.03% with a thickness of 490 μm to be the inner metal plate was prepared, and the area of the semiconductor chip mounting part of a 50 mm square package and its opposite surface was With the etching resist left, the metal plate was etched 140 μm from both sides to form a metal plate with a convex front and back. The etching resist was removed, and a liquid etching resist of 25 μm was adhered to the entire surface again, leaving a circular etching resist having a diameter of 300 μm at the center of the semiconductor chip mounting portion and a portion to be formed into a truncated conical projection formed on the back surface, and a clearance was provided. Except for the etching resist in the hole, the metal plate was dissolved by etching from above and below. Within 13 mm square at the center of the metal plate surface, the surface is 140 μm high and the bottom diameter is 655 μm
m, 256 frusto-conical projections with a top diameter of 199 μm and 64 on the back side, and a hole diameter around this frusto-conical projection.
A 0.6mmφ clearance hole was drilled (Fig. 1-f). The entire surface of the metal plate is subjected to black copper oxide treatment, and a semiconductor chip mounting portion of the prepreg B is punched out in a 15 mm square area (f) on the front and back surfaces, and a 12 μm electrolytic copper foil (a) is arranged above and below. Then, they were laminated and molded at 200 ° C. under a vacuum of 20 kgf / cm ² , 30 mmHg or less for 2 hours, and integrated. Thereafter, a circuit was formed on the copper foil on the surface, and after performing a black copper oxide treatment, a semiconductor chip mounting portion of the prepreg C was punched out in an area of 14 mm square (g) on the surface, and 12 μm was placed above and below it. An electrolytic copper foil was placed and laminated and formed under the same conditions to obtain a multilayer board. Through holes having a diameter of 0.25 mm were drilled in the clearance holes with a mechanical drill, and after desmearing, the whole was electrolessly plated with 15 μm copper by electrolytic plating (k) to form circuits on the front and back surfaces. The solder ball pad on the back was created avoiding the truncated cone. The copper foil directly above the metal foil on the center of the semiconductor chip is cut off with a router, a plating resist is formed on the semiconductor chip mounting part, the wire bonding part, and the ball pad part on the back surface, and nickel and gold plating are applied to the printed wiring board Was completed. After bonding the semiconductor chip (n) with a size of 13 mm square with silver paste (o) to the surface of the heat conductive copper foil in contact with the tip of the truncated conical protrusion that is the semiconductor chip mounting part on the surface, Perform wire bonding, then use a silica-containing epoxy sealing compound resin (q),
The semiconductor chip (n), the wire (p), and the bonding pad were sealed with a resin, and a solder ball (r) was bonded to the back surface to form a semiconductor package. This semiconductor plastic package was melt-bonded with a solder ball to an epoxy resin mother board printed wiring board. Table 1 shows the evaluation results.

Example 2 In Example 1, 5 μm of silver paste was applied on the truncated conical projection.
In place of the copper foil on the surface used at the time of the second lamination molding, one prepreg B was used, and a 12 μm electrolytic copper foil was placed on both sides of the prepreg. A board formed by forming a circuit on one side of the laminated board and subjected to black copper oxide treatment, a prepreg B is punched in place of the prepreg C, and the circuit side of the double-sided board is placed so as to face the prepreg side. Lamination molding was performed to obtain a multilayer board. A through hole for a through hole was made at the location of this clearance hole, and a blind hole having a hole diameter of 100 μm was made on the surface with a carbon dioxide gas laser. After desmearing, a thickness of 17 μm was applied by electroless copper plating. After forming the circuit on the front and back, the base material directly above the metal foil on which the semiconductor chip on the surface was mounted was cut and removed with a router, and sand was sprayed from the front side by sandblasting, and it flowed out onto the copper foil on which the semiconductor chip was mounted After the resin was removed, the portions other than the copper foil portion, the bonding pad portion, and the ball pad portion on the back surface, which were the semiconductor chip mounting portions, were covered with a plating resist, and nickel plating and gold plating were performed to produce a cavity-type multilayer printed wiring board. Similarly, a semiconductor chip was mounted, wire bonding and resin sealing were performed, solder balls were connected, and the chips were bonded to a motherboard printed wiring board. Table 1 shows the evaluation results.

Comparative Example 1 In Example 2, a solder ball pad on the back surface was formed on a truncated cone-shaped projection, and a semiconductor chip was mounted without removing the resin on the surface of the semiconductor chip mounting copper foil portion by sandblasting. A printed wiring board was prepared in the same manner and joined to a motherboard printed wiring board with solder balls. 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 molded 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, a semiconductor chip is bonded with a silver paste on this, and after wire bonding, resin sealing is performed with an epoxy sealing compound in the same manner as in Example 1. And 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 prepare a no-flow prepreg (prepreg D) having a gelling time of 10 seconds and a resin flow of 98 μm, and a high-flow prepreg (prepreg E) having a gelling time of 150 seconds and a resin flow of 18 mm. Using two pieces of this prepreg E, 190 ℃, 20kgf / c
Laminate molding was performed for 2 hours under a vacuum of m ² and 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. Bonding was similarly performed under heat and pressure to produce a printed wiring board with a heat sink. This slightly warped. A semiconductor chip was directly adhered to this heat sink with silver paste, connected by wire bonding, and sealed with liquid epoxy resin (Fig.
Four). Similarly, it was joined to a motherboard printed wiring board. Table 1 shows the evaluation results.

[0037] Table 1 Item implementation example comparisons Example 1 2 1 2 3 Ball shear strength 1.6 1.5 1.2 over over (kgf) heat resistance A after moisture absorption) normal state No change No change over No change No change 24hrs. Abnormality None No error-No error No error 48hrs. No error No error-No error No error 72hrs. No error No error-No error No error 96hrs. No error No error-No error Partial peeling 120hrs. No error No error-1 Partial peeling Partial peeling 144hrs. No abnormality No abnormality-Partial peeling Partial peeling 168hrs. No abnormality No abnormality-Partial peeling Partial peeling Heat resistance after moisture absorption B) Normal No abnormality No abnormality-No abnormality-No abnormality 24hrs No abnormality No abnormality-Partially peeled Partially peeled 48hrs. No abnormality No abnormality-No abnormality-Large peeled large peeled 72hrs. No abnormality-No abnormality-Wire break Wire break 96hrs. No abnormality No abnormality-Wire break Wire break 120hrs. No abnormalities No abnormalities-No broken wires 144hrs. No abnormalities No abnormalities---168hrs. No abnormalities No abnormalities---

[0038] 1 Item implementation example ratio Table compare Example 1 2 1 2 3 pressure cooker treatment after the insulation resistance (Omega) normal state 5X10 ¹⁴ 4X10 ¹⁴ over ^{6X10 14 6X10 14 200hrs. 6X10 12} 5X10 12 over 5X10 ¹² 5X10 ^{8 500hrs.} 7X10 ¹¹ 7x10 ¹¹ over ^{4X10 11 <10 8 700hrs. 4X10} 10 6X10 10 over 5X10 ¹⁰ over 1000hrs. 2X10 ¹⁰ 3X10 ¹⁰ over 2X10 ¹⁰ over migration resistance (Omega) normal state 5X10 ¹³ 6 × 10 ¹³ over 5X10 ¹³ 4X10 ¹³ 200hrs. 5X10 ¹¹ 5X10 ¹¹ over ^{4X10 11 3X10 9 500hrs. 6X10 11} 4X10 11 over ^{5X10 11 <10 8 700hrs. 3X10} 11 1X10 11 over 1X10 ¹¹ over 1000hrs. 9X10 ¹⁰ 9X10 ¹⁰ over 8X10 ¹⁰ over the glass transition temperature (° C.) 234 234 234 234 160 Heat dissipation (° C) 35 36 59 56 48

<Measurement Method> 1) Ball Shear Strength A solder ball was attached to a ball pad having a diameter of 0.6 mm, and the strength when peeled off 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.

[0040]

According to the present invention, a metal plate having substantially the same size as the printed wiring board is disposed substantially at the center in the thickness direction of the printed wiring board, and at least one semiconductor chip is thermally mounted on one surface of the printed wiring board. The circuit conductor is fixed with a conductive adhesive, the circuit conductor is connected to the semiconductor chip by wire bonding, and at least the circuit conductor on the surface of the printed wiring board and the circuit conductor or the semiconductor plastic package formed on the opposite surface of the printed wiring board Is connected to the outside by a solder ball conductor, and at least the semiconductor chip, wire, and bonding pad are resin-sealed. The metal projection to which the conductive adhesive or solder is attached, and a clearance hole or A prepreg, a resin sheet or a coating resin layer of a semi-cured thermosetting resin composition in which holes are formed slightly larger than the area of the semiconductor chip in the metal projections on the front and back surfaces of the metal plate in which the slit holes are formed. After placing the metal foil on the outside, laminating and molding under heat and pressure and integrating, form a circuit on the surface, chemically treat the metal foil surface, and outside the semiconductor chip area Placing a prepreg, resin sheet, or coated resin layer with holes that have been cut slightly larger, metal foil, a single-sided metal foil-clad board, or a circuit formed on one side, and chemically treated double-sided metal foil-clad A board or a double-sided metal foil-clad multilayer board is arranged so that the circuit side faces inward, and laminated under heat, pressure, preferably under vacuum to form a multilayer board, and through holes for through holes and blind holes are formed. Opening, Desumi After processing, metal plating is applied, and after forming a circuit on the front and back, a circuit is formed on the front and back, preferably avoiding the solder ball pad on the back on the truncated conical projection, and a metal foil just above the semiconductor chip mounting part on the front And / or after removing the base material, at least the metal foil for mounting the semiconductor chip on the front and back surfaces, the bonding pads, and the ball pads on the back surface are covered with a plating resist, and nickel-plated or gold-plated prints obtained by applying gold plating By using a wiring board, the semiconductor plastic package obtained using this has excellent adhesive strength with solder balls, does not absorb moisture from the lower surface of the semiconductor chip, and has significant heat resistance after moisture absorption, that is, a popcorn phenomenon. By using a polyfunctional cyanate resin composition as the resin, insulation after pressure cooker treatment can be improved. A multilayer printed wiring board for use in a semiconductor plastic package having a novel structure, which has excellent heat resistance and migration resistance, is suitable for mass production, and has improved economic efficiency, was obtained.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a semiconductor plastic package containing a metal core of Example 1.

FIG. 2 is a manufacturing process diagram of a semiconductor plastic package containing a metal core of Example 1.

3 is a manufacturing process diagram of a semiconductor plastic package of Comparative Example 1. FIG.

FIG. 4 is a manufacturing process diagram of a semiconductor plastic package of Comparative Example 2.

[Explanation of Symbols] a Copper foil b Pre-preg B c Part where the prepreg is cut off from the semiconductor chip mounting part d Metal core e Truncated cone-shaped projection f Clearance hole g Pre-preg Ch Ch Chemically treated circuit conductor i Through-hole for front and back circuit conduction Part j Resin flowing out of prepreg C k Copper plated part l Plating resist m Metal foil for mounting semiconductor chip n Semiconductor chip 0 Silver paste p Bonding wire q Sealing resin r Solder ball s Heat dissipation through hole t Prepreg D

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshihiko Kobayashi F-term (reference) 5E315 AA05 AA11 BB01 BB04 BB05 BB14 BB15 CC01 CC15 CC16 DD15 DD17 DD20 DD25 GG01 GG05 GG09 GG13 GG20

Claims (4)

[Claims] A metal plate having a size substantially the same as that of a printed wiring board is disposed on a part of the printed wiring board in a thickness direction, and at least one semiconductor chip is attached to one surface of the printed wiring board with a heat conductive adhesive. And insulate the metal plate and the signal transmission circuit conductor on the surface of the printed wiring board with a thermosetting resin composition,
To connect the circuit conductor and the semiconductor chip by wire bonding, and to connect at least the circuit conductor on the surface of the printed wiring board and the circuit conductor or the package formed on the opposite surface of the printed wiring board to the outside with solder balls. A printed wiring board for a semiconductor plastic package having a structure in which a formed circuit conductor pad is connected to a metal plate and a through-hole conductor insulated with a resin composition, and at least a semiconductor chip, a wire, and a bonding pad are resin-sealed. A plurality of truncated cone-shaped metal projections, or a metal projection having heat conductive adhesive or solder attached to the front and back, and a metal plate having a clearance hole or slit hole for forming a front and back conduction hole. On the back surface, the portion of the metal protrusion is cut off slightly larger than the area for mounting the semiconductor chip. A prepreg of a thermosetting resin composition in a cured state, a resin sheet, or a coating resin layer is arranged, a metal foil is placed outside the prepreg, heated, laminated and integrated under pressure, and then integrated.
After forming a circuit on the surface and chemically treating the metal foil surface,
A prepreg, resin sheet, or coated resin layer cut slightly larger than the area of the semiconductor chip is placed on the outside, and a metal foil, a single-sided metal foil-clad laminate, or a double-sided copper-clad board or a multilayer board is placed on it. After forming the circuit, place the surface treatment, so that the circuit side faces inward,
Laminate and mold under heat and pressure to create a multilayer board, drill through holes for blind holes, blind holes, apply metal plating after desmear treatment, form circuits on the front and back, on the metal foil on the surface of the semiconductor chip mounting part A metal core obtained by cutting at least a part of the metal foil for mounting a semiconductor chip on the front surface, bonding pads and a ball pad on the back surface with a plating resist, and performing nickel plating and gold plating. Multilayer printed wiring board for semiconductor plastic package. 2. A double-sided metal foil-clad multilayer board obtained by treating the resin flowing out onto the metal foil on the semiconductor chip mounting portion by sandblasting so that at least a metal surface of an area where the semiconductor chip is mounted is exposed. The printed wiring board for a semiconductor plastic package according to claim 1, wherein the printed wiring board is used. 3. The printed wiring board for a semiconductor plastic package according to claim 1, wherein said metal plate is a copper alloy containing 95% by weight or more of copper or pure copper. 4. The semiconductor plastic package 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. For printed wiring boards.