JP2000183228A - Semiconductor plastic package containing metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form semiconductor plastic package containing a metal plate into one is superior in electrical insulation properties, a migration resistance and the like, by a method wherein a metal foil formed by performing a chemical treatment on a one-sided metal foil-clad laminated board, a double-sided board with its one side formed with a circuit or a multilayer board is arranged, metal foils are arranged on the rear of the metal core, and a double-sided metal foil-clad board formed by lamination-molding the metal core and the metal foils under heating and pressing is used for the package. SOLUTION: Prepreg resin sheets (f) board with holes slightly larger than a metal projection part on the surface of a metal core or coated resin layers are respectively arranged on the front and back of the metal core, and copper foils are respectively arranged on the outsides of the sheets (f) or the resin layers. The sheets (f) or the resin layers and the copper foils are laminated under heating, pressing and a vacuum state to etch away the copper foils on trapezoidal projection parts on the surface of the metal core, the resin layer flowed out on the projections is removed and through-holes (g) are bored in the metal core by a drill or the like. A copper plating is applied to the whole metal core by a normal method through a soft etching process or the like, solder ball pads (n) on the rear of the metal core avoid the upper parts of the trapezoidal projection parts and are directly connected with the copper foils on the metal projection part through circuits to form the circuits in the whole metal core. The surface of the metal core is covered with a plating resist excluding the upper parts of the trapezoidal projection parts, which are used as a semiconductor chip (j) mounting part, a nickel plating is applied to the surface and a printed wiring board is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel metal-containing semiconductor plastic package having at least one semiconductor chip mounted on a small printed wiring board.
The resulting semiconductor plastic package is suitable for relatively high wattage, multi-terminal, high-density semiconductor plastic packages such as microprocessors, microcontrollers, ASICs, and graphics. The semiconductor plastic package of the present invention 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 through holes, moisture is absorbed by the resin adhesive containing silver powder used for fixing the semiconductor, and the interlayer blisters are heated by the heating at the time of mounting on the motherboard and the heating at the time of removing the semiconductor parts 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 semiconductor plastic package containing a metal plate in which the above problems are improved.

[0004]

According to the present invention, a metal plate having substantially the same size as a printed wiring board is disposed on a part of the printed wiring board in the thickness direction, and a trapezoidal projection is formed on the surface of the metal plate. The semiconductor chip is fixed on the projection with a heat conductive adhesive, and a plurality of truncated cone-shaped projections are provided on the back surface, and the metal plate and the circuit on the front and back surfaces are insulated with a thermosetting resin composition. The circuit conductor formed on the surface of the printed wiring board and the semiconductor chip are connected by wire bonding, and at least the signal propagation circuit conductor on the printed wiring board on the surface is connected to the circuit conductor formed on the opposite surface of the printed wiring board. Or a circuit conductor pad formed to connect with a solder ball to the outside of the package by a through-hole conductor insulated with a metal plate and a resin composition. Forming a trapezoidal protrusion and / or a clearance hole or a slit hole for a through-hole at a position other than the protrusion on the metal plate. On the surface having the shape protrusion, a prepreg hollowed out slightly larger than the protrusion,
Placing a resin sheet, coating resin layer or metal foil with resin,
A prepreg, resin sheet or coated resin layer that is slightly larger than the truncated cone-shaped protrusion is also placed on the back surface, and if there is no metal foil on the outside of the trapezoidal protrusion side surface, metal foil, single-sided metal foil laminated A board or a double-sided board or a multilayer board with a circuit formed on one side is chemically treated and placed so that the circuit side faces the resin layer, and a metal foil is placed on the back side,
Provided is a semiconductor plastic package containing a metal plate, which is formed using a double-sided metal foil clad plate laminated and formed under heating and pressure. Furthermore, in the above invention, a double-sided metal foil obtained by treating the resin flowing out to the top of the trapezoidal projection of the metal plate by sandblasting so that at least the surface of the metal plate on which the semiconductor chip is mounted is exposed. A semiconductor plastic package characterized by using a veneer is provided. The resulting semiconductor plastic package has excellent electrical and thermal conductivity, excellent solder ball adhesion to the substrate, no moisture absorption from the bottom surface of the semiconductor chip, and greatly improved heat resistance after moisture absorption, that is, the popcorn phenomenon. You. Furthermore, by using a polyfunctional cyanate ester composition as a thermosetting resin, the electric insulation after pressure cooker, excellent in migration resistance, etc.,
In addition, it is suitable for mass production and has improved economy.
A semiconductor plastic package having a new structure is obtained.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A semiconductor plastic package manufactured by using a copper-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. Having a trapezoidal projection on the surface of the metal plate, fixing a semiconductor chip with a thermally conductive adhesive on the projection surface at least partially exposed, and providing a plurality of truncated cone-shaped projections on the back surface, The metal plate and the circuit on the front and back are insulated with the thermosetting resin composition, the circuit conductor formed on the surface of the printed wiring board and the semiconductor chip are connected by wire bonding,
At least a signal propagation circuit conductor on the printed wiring board on the front surface, a circuit conductor formed on the back surface of the printed wiring board, or a circuit conductor pad formed for connection to the outside of the package with a solder ball. A semiconductor plastic package having a structure in which at least a semiconductor chip, a wire, and a bonding pad are resin-sealed by being connected with a metal plate and a through-hole conductor insulated with a resin composition, and having a trapezoidal shape on the surface of the metal plate; Clearance holes or slit holes for through holes are formed at locations other than the protrusions, and a plurality of truncated cone-shaped protrusions are formed on the back surface facing the trapezoidal protrusions, covering the trapezoidal and truncated cone-shaped protrusions Prepreg, resin sheet,
A coated resin layer or a metal foil with resin is arranged so as to be slightly thicker than the height of the metal projection, and a metal foil, a single-sided metal foil-clad laminate, or a single-sided metal foil is used except for using a metal foil with a resin on the surface. A circuit is formed and a double-sided board or multilayer board subjected to chemical treatment is arranged so that the circuit side faces inward, a metal foil is arranged on the back side, and laminated and formed under heat and pressure, preferably under vacuum Manufactured. The obtained double-sided metal foil clad board
It is preferable that the resin layer that has flowed out onto the trapezoidal protrusions is processed by sandblasting so that the metal surface is exposed at least in an area where the semiconductor chip is mounted. Drill through holes or slits in through holes or slit holes filled with thermosetting resin so as not to contact the inner metal plate, if necessary after desmear treatment, after metal plating the whole, A solder ball pad for heat dissipation is provided on the part of the truncated cone-shaped metal projection so as to connect to it, and at least the bonding pad and the surface other than the solder ball pad on the back surface are covered with a plating resist, and nickel plating and gold plating are applied. To make a printed wiring board. The semiconductor chip is fixed on the trapezoidal protrusion on the surface of the metal plate with a heat conductive adhesive, the semiconductor chip and the surrounding circuit conductor are connected by wire bonding, and at least the semiconductor chip, the bonding wires, and the bonding pads are resin-sealed. The solder ball pad connected to the metal foil on the noble metal-plated frustoconical projection on the back side is soldered to the motherboard printed wiring board with solder, and the front and back circuit conductors and plated through holes for conduction Has a structure insulated from a metal plate by a thermosetting resin composition.

In the technology of fixing a semiconductor chip on the upper surface of a printed wiring board having a conventionally known through hole, heat from the semiconductor chip is dropped to a heat dissipation through hole immediately below, similarly to a conventional P-BGA package. The heat must be dissipated, and the popcorn phenomenon cannot be improved. The present invention forms a trapezoidal metal projection on the front surface and a truncated conical metal projection on the back surface on both surfaces of a metal flat plate in advance by a known method such as etching, and forms a clearance hole or a slit hole. Place a prepreg, resin sheet, etc., with holes slightly larger than the area of the projections, so that they do not cover the metal projections, so that the surface is slightly higher than the height of the projections. A resin layer such as a prepreg is preferably provided so as to be 1 to 5 μm lower than the metal projection, and a metal foil is not attached to the surface, and a metal foil, a metal foil-clad board or a circuit is formed on one side. A surface-treated double-sided board or multilayer board is arranged so that the circuit side faces inward, a metal foil is arranged on the back side, and laminated under heat, pressure, and preferably under vacuum, and both sides containing an inner metal plate are placed. Manufacture metal foil cladding Using this, a printed wiring board is formed by an ordinary method. The method of forming the metal plate is not particularly limited. For example, first, about の of the metal plate in the thickness direction is etched off from both sides in the thickness direction except for the area where the metal protrusion is formed on both surfaces of the metal plate. . After removing the etching resist, cover the entire surface again with a liquid etching resist,
The etching resist is left in a circular shape at the place where the truncated cone-shaped metal protrusion is formed on the back surface, and the etching resist is also left on the entire surface at the trapezoidal protrusion on the front surface, and at the same time, the etching resist at the place where a clearance hole or slit hole is formed Remove and etch with an etchant from both sides to form trapezoidal protrusions on the front surface and frustoconical protrusions on the back surface, and at the same time, form a metal plate for printed wiring board by forming a clearance hole or slit hole. create.

The surface of a metal plate having a trapezoidal projection, a truncated conical projection and a clearance hole or a slit hole is formed by a known method to improve adhesion and electrical insulation such as oxidation treatment, formation of fine irregularities, and film formation. Is applied as necessary. In the trapezoidal protrusions on the surface that has been surface-treated, the prepreg, resin sheet,
A coated resin layer or a metal foil with resin is arranged so as to be slightly higher than the height of the trapezoidal projection, and the metal foil on the outside without metal foil, a copper-clad board with a circuit formed on one side or A prepreg with a multilayer plate chemically treated and placed with the circuit side facing inward, while a hole slightly larger than the area of the truncated conical projections is formed on the back side where a plurality of truncated conical projections are formed. , Resin sheet or coating resin layer,
Arranged so that it is slightly lower than the height of the truncated cone-shaped projection, put a metal foil on the back side, heat, press under, preferably laminated under vacuum, fill the clearance hole or slit hole with thermosetting resin . At the same time, a double-sided metal foil clad board is created such that the metal protrusions bite into the metal foil part on the back surface and are joined.

In the obtained double-sided metal foil-clad laminate, a through hole is formed in a place where a clearance hole or a slit hole is formed so as not to contact the metal plate by a known method such as a mechanical drill or a laser. Desmear treatment is performed and the whole is metal-plated. When a metal foil is used on the surface, the metal foil on the trapezoidal projection is also removed by etching at the time of forming a circuit. The metal foil at the part where the tip of the truncated cone on the back surface is in contact with the surface metal foil is left.
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 surface layer of the semiconductor chip mounting portion, the bonding pad portion,
Then, a portion other than the solder ball pad portion on the back surface is covered with a plating resist and plated with nickel and gold to form 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. 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 conducts heat from the semiconductor chip mounting portion, passes through the trapezoidal projection of the metal core, transmits to the metal core, and conducts to the solder ball pad through the metal trapezoidal projection on the opposite surface, Diffusion to motherboard printed wiring boards joined by solder balls.

The side surface of the metal plate may be in a form coated with the thermosetting resin composition or in an exposed form, but from the viewpoint of preventing rust, etc., the thermosetting resin composition is used. It is preferable to coat with.

The through hole for the front and back signal circuits is formed substantially at the center of the 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. Alternatively, after plating, a film is formed on at least the surface other than the bonding pad and the opposite surface of the solder ball bonding pad with a known thermosetting resin composition or a photo-selective thermosetting resin composition as necessary. In this case, a resist is partially applied on the trapezoidal projection on which the semiconductor chip is mounted on the surface to form a coating, and the metal portion is exposed.

[0012] A semiconductor chip is fixed on the trapezoidal projection of the printed wiring board using a thermally conductive adhesive, and further, the semiconductor chip and a bonding pad of the printed wiring board circuit are connected by a wire bonding method. , The semiconductor chip, the bonding wires, and the bonding pads are sealed with a known sealing resin.

[0013] 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, the solder ball is superimposed on a circuit on a motherboard printed wiring board, and the ball is melt-connected by heat. Alternatively, 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 pads are connected by heating and melting the solder balls.

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 30 to 500 μm is suitable. 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 plate or the like in which the surface of the alloy is plated with copper may be used.

The height of the trapezoidal projection or the truncated conical projection of the metal plate of the present invention is not particularly limited, but is preferably 50 to 150 μm. The thickness of the insulating layer such as a prepreg or a resin sheet is slightly lower than the height of the metal truncated conical projection, preferably lower by 1 to 5 μm, and after lamination molding, it is brought into contact with at least a part of the surface metal foil by pressure. In this case, a lead-free solder, a heat conductive adhesive, or the like may be adhered on the truncated cone-shaped protrusion, and the protrusion may be connected to the outer metal foil. The size of the truncated cone in the truncated cone-shaped projection is not particularly limited, but generally, the diameter of the bottom is 0.5 to 5 mm, and the diameter of the top is 0.
~ 1mm. On the other hand, there may be a problem that the resin flows out onto the trapezoidal trapezoid and is covered with the resin. In this case, the resin that has flowed out by the sandblasting method after the lamination molding is removed, and at least the surface of the metal plate is covered with a semiconductor. It is preferable that the exposed area be larger than the area for mounting the chip.

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 a resin or the like on the surface is removed by shaving. As the particles, generally known powders such as glass beads of about 40 μm and silicon carbide are used.

The formation area of the trapezoidal projections and the truncated conical projections of the metal plate may be smaller than the area of the semiconductor chip, but is preferably slightly larger, generally within 5 to 20 mm square. To be on the opposite side. In the ball pad portion on the back surface, preferably, a ball pad is formed avoiding a portion on the metal foil in contact with the metal protrusion portion on the back surface, and the ball pad and the circuit are connected to the metal foil on the protrusion. In addition, the adhesive strength between the ball pad portion and the substrate is maintained so that peeling due to insufficient strength (ball shear strength) when a ball is pressed from the side is less likely to occur.

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 an appropriate combination in consideration of the balance of properties.

Various additives can be added to the thermosetting resin composition of the present invention, if desired, as long as the inherent properties of the composition are not impaired. These additives include polymerizable double bond-containing monomers such as unsaturated polyesters and prepolymers thereof; polybutadiene, epoxidized butadiene, maleated butadiene, butadiene-
Low molecular weight liquid to high molecular weight elastic rubbers such as acrylonitrile copolymer, polychloroprene, butadiene-styrene copolymer, polyisoprene, butyl rubber, fluororubber, natural rubber; polyethylene, polypropylene, polybutene, poly-4-methyl Penten, polystyrene, AS
Resin, ABS resin, MBS resin, styrene-isoprene rubber,
Polyethylene-propylene copolymer, 4-fluoroethylene-
6-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 economic efficiency. Can be used. The amount used is 0.005 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the thermosetting resin.

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 thickness of the metal foil of the inner layer is preferably 12-70
μm.

The diameter of the clearance hole or the width of the slit formed in the metal plate is slightly larger than the diameter of the through hole for front and 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 the prepreg for a printed wiring board of the present invention, the 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 and a metal foil with a resin can also be used. Alternatively, paints can be used. The temperature for forming a 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 a metal plate (FIG. 1, b) serving as a metal core is coated with a liquid etching resist (FIG. 1, a), and after removing the solvent by heating, a portion for fixing a semiconductor chip, and a metal on an opposite surface. The resist in the area where the truncated cone-shaped projections are formed is entirely left, and the other parts are etched so that the thickness of the metal plate becomes about 1/2. (2) After removing the etching resist, (3) Cover the entire surface again with a liquid etching resist (FIG. 1, a), leave the entire surface etching resist on the trapezoidal projection on which the semiconductor chip is mounted, and further back. Leave the resist in a circular shape on the part to be left as a truncated cone-shaped protrusion, and in addition, leave all the resist except the clearance hole part. (4) Etching with an etching solution from above and below by etching, convex protrusion on the surface, At the same time as forming a truncated cone-shaped projection (FIG. 1, d) on the back surface, a clearance hole (FIG. 1, c) is formed. (5) On the front and back, a prepreg resin sheet (FIG. 1, f) or a coating resin layer having a slightly larger hole than the metal protrusion is disposed, and a copper foil (FIG. 1, e) is disposed outside thereof. 6) After laminating and molding under heat, pressure and vacuum, the copper foil on the trapezoidal projections on the surface is removed by etching, and the resin that has flowed onto the projections is removed by sandblasting, and the through holes (FIG. , G) with a drill etc. (7) The whole is plated with copper through a soft etching process or the like by a conventional method, and a solder ball pad on the back surface of the metal core (FIG. 2,
n) avoiding the truncated cone-shaped protrusions and connecting directly to the copper foil on the metal protrusions by a circuit to form a circuit as a whole, and the trapezoidal shape of the surface to be the mounting portion for the semiconductor chip (FIG. 2, j) The printed wiring board is formed by covering with a plating resist, excluding the bonding pad and the solder ball pad portion on the protruding portion, and performing nickel plating and gold plating. A semiconductor chip is bonded and fixed on the projection on the surface with a silver paste, and after wire bonding, at least the semiconductor chip, wires, and 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.

[0031]

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 while 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 ℃)
A prepreg B in a semi-cured state having an insulating layer thickness of 147 μm and a prepreg C having a thickness of 137 μm were prepared so that the resin flow was 10 mm in 5 seconds at 170 ° C., 20 kgf / cm ² and 5 minutes. On the other hand, 420 μm thick Cu: 99.9%, Fe: 0.07%, which becomes the inner metal plate,
P: Prepare an alloy plate of 0.03%, leave the etching resist on the semiconductor chip mounting part of the 50 mm square package and the area on the opposite surface, etching 140 μm from both sides to make the metal part with a convex front and back center part . After removing the resist, a liquid etching resist is applied to the entire surface in a thickness of 25 μm, leaving a circular etching resist having a diameter of 300 μm in a central portion of the semiconductor chip mounting portion and a portion serving as a truncated conical projection formed on the back surface, and a clearance hole portion. The etching resist was removed, and the metal plate was dissolved by etching from above and below. A trapezoidal protrusion with a height of 140 μm is created within a 13 mm square at the center of the surface of the metal plate, and 100 truncated cone-shaped protrusions with a height of 140 μm, a bottom diameter of 655 μm, and a top diameter of 212 μm are created on the back surface, and a clearance hole with a hole diameter of 0.6 mmφ is created. Opened. The entire surface of the metal plate was subjected to a black copper oxide treatment, and the prepreg B having the metal projections punched on the front surface thereof and the prepreg C on the back surface thereof were placed thereon.
Was placed, laminated and molded at 200 ° C., 20 kgf / cm ² , and a vacuum of 30 mmHg or less for 2 hours, and integrated. After that, the resin that flowed out onto the surface trapezoidal projections by sandblasting was removed, exposing the metal surface of the projections surface, and 0.25 mm in diameter
Was drilled in the clearance hole with a mechanical drill, and after desmearing, copper plating was applied 20 μm by electroless and electrolytic plating. An etching resist is attached to the front and back, leaving a solder ball pad with a diameter of 0.6 mm on the front surface, leaving the entire surface of the semiconductor chip mounting part where the protrusion is in contact with the metal foil, and on the back surface avoiding the location on the truncated cone-shaped protrusion. This is connected to the copper foil on the protrusion by a circuit to form a circuit as a whole. After the resist is dissolved and removed, plating resist is applied to the semiconductor chip mounting part, wire bonding part, and the ball pad part on the back surface. Was formed and plated with nickel and gold to complete a printed wiring board. After bonding and fixing a 13 mm square semiconductor chip with a silver paste on the copper surface of the trapezoidal protrusion that is the semiconductor chip mounting part on the surface, wire bonding is performed, then using silica-containing epoxy sealing compound resin, The semiconductor chip, wires, and bonding pads were sealed with resin, and solder balls were 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. Show evaluation results
Shown in 1.

Example 2 In Example 1, one prepreg B from which a trapezoidal projection was punched out was used, and an electrolytic copper foil of 12 μm was placed on both sides thereof. After forming a circuit and arranging a plate subjected to black copper oxide treatment, and laminating and molding in the same manner, sand is blown from the front side by sand blasting method, and the laminated plate on the protrusion is removed, and the surface of the protrusion is removed. After removing the resin that has flowed out, form a circuit on the front and back, cover the surface trapezoidal projections, the bonding pads, and the ball pads on the back, which are the semiconductor chip mounting parts, with plating resist, and apply nickel plating and gold plating A multilayer printed wiring board was created. Similarly, solder balls were connected and joined to a motherboard printed wiring board. Table 1 shows the evaluation results.

COMPARATIVE EXAMPLE 1 A printed wiring in Example 2 in which a semiconductor chip was mounted without removing the resin on the surface of the trapezoidal projection by the sandblasting method, and a ball pad on the back surface was formed on the truncated conical projection. A board was similarly prepared 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 foil was placed 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 an epoxy resin (trade name: Epicoat 5045, manufactured by Yuka Shell Epoxy Co., Ltd.) and an 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 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.

Table 1 Item Example Comparative example 1 1 2 3 3 Ball shear strength 1.6 1.5 1.2 ー ー (kgf) Heat resistance after moisture absorption A) Normal No abnormality No abnormality No abnormality No abnormality No abnormality 24hrs. Abnormal None No abnormalities-No abnormalities No abnormalities 48hrs. No abnormalities No abnormalities-No abnormalities No abnormalities 72hrs. No abnormalities No abnormalities-No abnormalities No abnormalities 96hrs. No abnormalities No abnormalities-No abnormalities Partial peeling 120hrs. No abnormalities No abnormalities-One Partial peeling Partial peeling 144 hrs. No abnormality No abnormality-Partial peeling Partial peeling 168 hrs. No abnormality No abnormality-Partial peeling Partial peeling Heat resistance after moisture absorption B) Normal No abnormality No abnormality-No abnormality 24 hours 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. Cutting 120hrs No abnormality No abnormality over wire breakage wire breakage 144hrs No change No change over -.. -. 168hrs No problem Not determined - -

[0037] Table 1 (Continued) Item implementation example comparisons 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. 5X10 12} 6X10 12 over ^{5X10 12 5X10 8 500hrs. 5X10 11} 5x10 11 over ^{3X10 11 <10 8 700hrs. 6X10} 10 5X10 10 over 4X10 ¹⁰ over 1000hrs. 4X10 ¹⁰ 3X10 ¹⁰ over 2X10 ¹⁰ over migration resistance (Omega) normal state 5X10 ¹³ 6 × 10 ¹³ over 5X10 ^{13 4X10 13 200hrs. 6X10 11 5X10} 11 over ^{4X10 11 3X10 9 500hrs. 6X10 11} 6X10 11 over ^{4X10 11 <10 8 700hrs. 2X10} 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) 33 34 45 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 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 process 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 the above 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 before measuring the package temperature.

[0039]

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 a part of the surface of the printed wiring board forms a trapezoidal projection. Fixing at least one semiconductor chip thereon with a heat conductive adhesive, insulating the metal plate and the surface circuit with a thermosetting resin composition such as a polyfunctional cyanate ester, The circuit conductor formed on the surface of the printed wiring board and the semiconductor chip are connected by wire bonding, and a plurality of metal truncated cone-shaped protrusions are formed on the opposite surface where the semiconductor chip is mounted, and the tips of the protrusions are on the back surface. It is connected in contact with the metal foil, preferably forming a solder ball pad avoiding the contact portion, at least a signal propagation circuit conductor on the printed wiring board on the surface and the opposite surface of the printed wiring board Circuit formed A semiconductor having a structure in which a conductor or a ball pad for connection with the solder ball 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 prepreg which is a plastic package and has holes slightly larger than the area of the trapezoidal protrusions on the front surface and the plurality of metal protrusions on the back surface formed on the metal plate which is to be a part of the printed wiring board. A resin sheet, a coated resin layer or a metal foil with a resin is placed, and a metal foil, a single-sided metal foil-clad laminate or a circuit formed on one side is formed on the outside of the surface, and a metal surface-treated plate is placed on the circuit side inside. Metal foil is placed on the outside of the resin layer on the back side, and laminated under heat and pressure, preferably under vacuum, to form a clearance hole or slit formed on the metal plate. The resin is filled into the holes, and the resin is poured into and filled between the truncated conical protrusions at the center of the back surface, and the tip of the metal protrusion is partially brought into contact with the surface metal foil on the back surface to create a double-sided copper-clad plate, The resin layer that has flowed out onto the trapezoidal projections is removed by sandblasting to expose the tops of the trapezoidal projections, preferably with a structure in which a solder ball pad for heat dissipation is formed other than the tip of the metal projection on the back surface. A semiconductor plastic package obtained by bonding and fixing a semiconductor chip with a heat conductive adhesive on a trapezoidal projection serving as a semiconductor chip mounting portion of a printed wiring board for a semiconductor plastic package, wire bonding, and resin sealing, The solder balls adhered to the similarly gold-plated pads on the back side are melted and joined to the motherboard printed wiring board. The heat generated from the semiconductor chip is
Through the heat conductive adhesive, it is transmitted from the upper trapezoidal projection to the metal plate, escapes to the solder ball bonded to the ball pad part on the back through the lower truncated conical projection, and diffuses to the motherboard printed wiring board By this, the connection reliability between the inner layer metal plate and the outer layer copper foil, excellent heat dissipation, excellent adhesive strength with solder balls, no moisture absorption from the lower surface of the semiconductor chip, heat resistance after moisture absorption, Popcorn phenomenon can be greatly improved. In addition, by using a polyfunctional cyanate ester resin composition as a resin, the resin composition also has excellent electrical insulation properties and migration resistance after pressure cooker treatment. According to the present invention, there is provided a semiconductor plastic package having a novel structure which is suitable for mass production and has improved economy.

[Brief description of the drawings]

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

FIG. 2 is a manufacturing process diagram of the semiconductor plastic package containing a metal plate 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 Etching resist b Metal plate c Clearance hole d Truncated cone projection e Metal foil f Pre-preg B g Through-hole perforation h Sealing resin i Bonding wire j Semiconductor chip k Thermal conductive adhesive l Through-hole for front and back circuit conduction m Plating Resist n Solder ball 0 Through hole for heat dissipation p Prepreg D q Trapezoidal projection

Claims (4)

[Claims] 1. A metal plate having substantially the same size as a printed wiring board is disposed on a part of a thickness of the printed wiring board, and a trapezoidal projection is provided on a surface of the metal plate, and a semiconductor is provided on the projection. The chip is fixed with a heat conductive adhesive, a plurality of truncated cone-shaped projections are provided on the back surface, the metal plate and the circuit on the front and back surfaces are insulated with a thermosetting resin composition, and formed on the surface of the printed wiring board. The circuit conductor and the semiconductor chip are connected by wire bonding, and at least the signal propagation circuit conductor on the printed wiring board on the surface is connected to the circuit conductor formed on the opposite surface of the printed wiring board or to the outside of the package. A ball pad formed for connection with a solder ball is connected to a metal plate and a through-hole conductor insulated with a resin composition, and at least a semiconductor chip, a bonding wire and a bonding pad are connected. A semiconductor plastic package having a resin-encapsulated structure, wherein a trapezoidal projection and a clearance hole or slit for a through hole are formed on the metal plate at locations other than the trapezoidal projection, and a surface having the trapezoidal projection is formed. Is provided with a prepreg, a resin sheet, a coating resin layer or a metal foil with resin slightly larger than the trapezoidal projection, and a prepreg, a resin sheet or coating resin slightly larger than the trapezoidal projection on the back surface. If the layers are arranged and the metal foil is not attached to the outside of the trapezoidal protrusion side surface, the metal foil, single-sided metal foil-clad laminate, or double-sided board or multilayer board with a circuit formed on one side is treated as a circuit Arrange so that the side faces the resin layer, place metal foil on the back side, heat,
A semiconductor plastic package containing a metal plate, which is produced using a double-sided metal foil clad laminate formed under pressure. 2. A double-sided metal foil-clad board obtained by treating a resin that has flowed to the top of a trapezoidal projection of a metal plate by sandblasting so that at least a metal surface of an area where a semiconductor chip is mounted is exposed. 2. The method according to claim 1, wherein
Semiconductor plastic package as described. 3. The semiconductor plastic package according to claim 1, wherein the metal plate is made of 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. .