JP2000315749A - Printed wiring board for metal core-containing ball grid array type semiconductor plastic package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metal core-containing printed wiring board, which is excellent in a heat dissipation property, a heat resistance subsequent to moisture absorption and the like and has two-step wire bonding pads. SOLUTION: First, a plurality of truncated core-shaped projections (c) are formed on places on the rear directly opposite to the surface, which is mounted with a semiconductor chip, of a metal plate (a) and clearance holes (d) or slit holes are formed in places other than the places on the rear. Then a glass fiber base material prepreg (h) is put on the flat surface of the metal plate (a) and a substrate (k) with two-step bonding pads (i) formed on the one side of the double-sided copper-clad laminated board is put on the prepreg (h) in such a way that the side of circuits turns inward, prepregs (f) formed by hollowing out the parts of the projections (c) are arranged on the rear and after the substrate (k), the prepreg (h) and the prepregs (f) are lamination-molded on a semiconductor chip (l), a copper foil, a glass fiber base material and a resin on the surface of the metal plate (a) are cut in two times and a cavity type printed wiring board is formed. Moreover, a multifunctional ester cyanate resin composition is used as a thermosetting resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board for a ball grid array type semiconductor plastic package containing a metal core, wherein at least one semiconductor chip is mounted on the printed wiring board. The resulting printed wiring board is used for relatively high wattage, multi-terminal, high-density semiconductor plastic packages such as microprocessors, microcontrollers, ASICs, and graphics.
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. Conductor pads are formed on the upper surface of the printed wiring board, and solder pads are used on the lower surface of the printed wiring board to form conductor pads for connection to the motherboard printed wiring board. 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 the semiconductor chips with a resin 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 An object of the present invention is to provide a printed wiring board for a semiconductor plastic package containing a metal core in which the above problems are improved.

[0004]

That is, the present invention relates to a metal plate having a flat upper surface, a truncated conical projection on the lower surface, and a clearance hole or a slit hole formed therearound. A glass cloth base thermosetting resin prepreg is placed on the outside, and a double-sided copper-clad laminate with a copper circuit and an inner layer circuit formed on one side as a second-stage bonding pad is chemically treated as necessary, The circuit side faces the prepreg side, the frustoconical projection part is placed on the lower surface, the prepreg hollowed out slightly larger than its area is placed, and the copper foil is layered on the outside, heating, pressing,
Preferably, after lamination molding under vacuum and integrated, after forming a through hole for a through hole so as not to contact the metal plate, at the approximate center of the clearance hole or slit hole filled with resin, and through hole plating, The copper foil on the surface in contact with the truncated conical projection on the back surface is formed as a solder ball pad for heat dissipation and its connection circuit, and the front surface forms the first stage pad for wire bonding the semiconductor chip and its connection circuit, Next, the region of the semiconductor chip mounting cavity portion and the second-stage bonding pad portion, first, the glass cloth base material and the thermosetting resin composition layer on the surface until the second-stage bonding pad surface is exposed, Preferably, it is removed by sand blasting, and if necessary, the second-stage bonding pad is covered and protected with a resist, a mask metal or the like. Only the semiconductor chip mounting part is exposed to the inner metal core by cutting and removing the glass cloth base material and the thermosetting resin layer on the surface by sandblasting or the like only to the metal core of the inner layer, thereby exposing the metal core of the inner layer. A plating resist is adhered to portions other than the second-stage wire bonding pad portion and the solder ball pad portion, and a noble metal plating is applied thereto to produce a printed wiring board. Using this printed wiring board, a semiconductor chip is bonded and fixed to the surface of the metal core of the cavity with a thermally conductive adhesive, and after wire bonding, it is sealed with a sealing resin, and then solder balls are melt-connected to the back surface to form a semiconductor plastic. Package. The obtained semiconductor plastic package has excellent thermal conductivity, does not absorb moisture from the lower surface of the semiconductor chip, and can significantly improve heat resistance after absorbing moisture, that is, the popcorn phenomenon. Furthermore, by using a polyfunctional cyanate ester composition as a thermosetting resin, it is excellent in electric insulation after a pressure cooker, migration resistance, etc., and is also suitable for mass production, thereby improving economic efficiency. In addition, a semiconductor plastic package having a novel structure was obtained. .

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the printed wiring board for a semiconductor plastic package of the present invention will be described in detail below. First, a metal plate having substantially the same size as the printed wiring board is arranged in a part in the thickness direction, and the surface of the printed wiring board on which the semiconductor chip is mounted is a cavity type, and the metal core is exposed. At least one or more semiconductor chips are fixed on the surface of the exposed portion, the metal plate and the signal propagation circuit conductor on the surface of the printed wiring board are insulated with a thermosetting resin composition, and the circuit conductor and the semiconductor chip are separated. Connect by wire bonding. On the opposite side of the printed wiring board, a truncated cone-shaped projection from the inner layer metal core is connected in contact with the copper foil on the surface layer, and a circuit conductor connected to this projection or a circuit conductor pad for connecting the package to the outside with a solder ball, At least the circuit conductor on the surface is connected with a through-hole conductor insulated from the metal plate and the resin composition. At least the semiconductor chip, wires, and bonding pads are resin-sealed. The present invention relates to a printed wiring board used for a ball grid array type semiconductor plastic package having the above structure.

First, in a metal plate serving as a metal core, the surface of the metal plate on which the semiconductor chip is mounted is flat, and a plurality of truncated conical projections are formed on the opposite surface. A clearance hole or a slit hole is formed in a portion other than the semiconductor chip mounting portion and the truncated conical protrusion. Next, a glass cloth base material prepreg is placed on a flat surface of a metal plate on which a semiconductor chip is mounted, and a double-sided copper-clad with a single-sided circuit on which a circuit to be used as a second-stage bonding pad and an inner-layer circuit are formed. The laminate is disposed such that the copper foil surface is chemically treated as necessary, and the circuit side faces inward.
On the opposite side with the frustoconical metal projection, layer a glass cloth base prepreg that is slightly larger than the area of the projection part, place a copper foil on the outside, and heat, press, preferably laminate under vacuum A double-sided copper-clad multilayer board obtained by molding is used. Near the center of the clearance hole or slit hole,
A through hole is formed so as not to contact the metal core, desmearing is performed if necessary, and then the whole is plated with copper.
Thereafter, the copper foil, the glass cloth base material, and the thermosetting resin composition on the surface on which the semiconductor chip is to be mounted and the region to be the second-stage bonding pad portion are preferably cut and removed by sandblasting. To expose the second-stage bonding pad. At this time, if necessary, a protective film, a protective metal, or the like is provided on the second-stage bonding pad portion to protect it from being cut. The glass chip substrate and the thermosetting resin composition are cut and removed from the semiconductor chip mounting portion by a sand blast method or the like until the semiconductor chip mounting portion reaches the metal core, thereby exposing the inner layer metal core. The first-stage bonding pad and circuit are formed on the front surface, and the copper foil contacted by the truncated conical projection on the back surface is formed with a solder ball pad for connecting solder balls for heat radiation and a circuit for connecting the solder ball pad, at least,
A semiconductor chip, a wire bonding pad and a solder ball pad are covered with a plating resist, and nickel plating and gold plating are performed to produce a printed wiring board.

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

In the case of a known method of fixing a semiconductor chip on the upper surface of a metal-core printed wiring board having through holes, heat from the semiconductor chip is directly below the heat dissipation through holes as in a conventional P-BGA package. The heat must be dissipated and the popcorn phenomenon cannot be improved. The present invention provides a semiconductor plastic package that does not have a through-hole formed under a semiconductor chip mounting surface, does not absorb moisture from the back surface, is extremely unlikely to have a popcorn phenomenon, and has excellent heat dissipation. I do.

The method of forming the metal core according to the present invention is not particularly limited. For example, first, the etching resist on the rear surface of the flat metal plate in the range of forming the truncated cone-shaped metal protrusion is left in a circular shape, and the clearance hole or the surface of the surface is formed. The etching resist at the position where the slit hole is to be formed is removed, and etching is performed from both sides to form a truncated conical projection on the back surface, and at the same time, a clearance hole or a slit hole is formed around the periphery. In this case, the size of the truncated cone-shaped projection is not particularly limited, but preferably, the diameter of the trapezoid upper part is 0 to 1 mm and the diameter of the lower part is 0.5 to 5 mm. The surface of the metal plate on which the truncated cone-shaped protrusions and the clearance holes or slit holes are formed requires a surface treatment for improving adhesion and electrical insulation such as oxidation treatment, formation of fine irregularities, and film formation by a known method. Apply according to. A heat conductive adhesive or solder may be attached to the truncated conical projection. In the portion of the truncated cone-shaped protrusion on the back side subjected to the surface treatment, the glass cloth base material prepreg punched slightly larger than the area of the protrusion is slightly lower than the height of the truncated cone-shaped protrusion after lamination molding. To place. A copper foil is placed on the outside of the prepreg, an unprocessed glass cloth base prepreg is placed on the surface, and a bonding pad and a circuit as a second step are formed on the outside of the prepreg. Treated double-sided copper-clad laminate (in this case, a multilayer board may be used)
Is arranged so that the circuit side faces inward, and heated, pressed, preferably laminated and formed under vacuum, and filled with a thermosetting resin in a clearance hole or a slit hole, and the tip of a truncated conical metal projection is formed on the surface layer. Either cut into the metal foil or make strong contact and join to form a double-sided copper-clad multilayer board with a metal core. As the prepreg, a glass cloth base prepreg is preferred from the viewpoint of strength and the like, but of course, an organic base prepreg can also be used and is not limited.

In the obtained double-sided copper-clad multilayer board, a through hole is formed at a place where a clearance hole or a slit hole is formed so as not to contact a metal core by a known method such as a mechanical drill or a laser. Plate. A ball pad is formed so as to avoid a place where the tip of the truncated cone-shaped protrusion on the back surface is in contact with the surface copper foil or to avoid such a place. In this case, the ball pad is connected to the copper foil on the metal projection by a circuit so that a circuit is formed by a generally known method. The surface of the semiconductor chip and the copper foil, the glass cloth base material and the thermosetting resin on the second-stage wire bonding pad portion are exposed by a method such as counterboring, sandblasting, or the like, and the second-stage bonding pad is exposed. Then, the semiconductor chip mounting portion is cut and removed up to the metal core in the inner layer to expose the metal core, thereby producing a cavity type substrate. After forming the circuit on the front and back, at least the semiconductor chip mounting part, the bonding pad part, and the solder ball pad part on the back surface are covered with 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 front surface with a heat conductive adhesive, wire-bonded, and resin-sealed, and the back surface is melt-connected with a solder ball to form a semiconductor plastic package. The solder ball pad on the back is joined to the motherboard printed wiring board with solder balls. The heat generated from the semiconductor chip is conducted from the semiconductor chip mounting portion, passes through the truncated metal conical protrusion on the opposite side of the metal core to the solder ball pad, and diffuses to the motherboard printed wiring board joined by the solder ball. .

Regarding the side surface of the metal plate, any of a shape embedded with the thermosetting resin composition and an exposed shape may be used, but the thermosetting resin composition is used in view of prevention of rust generation and the like. 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, noble metal plating is formed on at least the surfaces of the semiconductor chip mounting portion, the bonding pad portion, and the solder ball pad portion to complete the printed wiring board. In this case, a portion that does not require noble metal plating is covered with a plating resist in advance. Or, after plating, if necessary, a known thermosetting resin composition, or a photoselective thermosetting resin composition, at least a semiconductor chip mounting portion, a bonding pad portion,
A film is formed on the surface other than the solder ball pad on the opposite surface.

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

A P-BGA is formed by connecting solder balls to solder ball connection conductor pads on the opposite side of the semiconductor chip, and the solder balls are superimposed on a circuit on a motherboard printed wiring board, and the balls are melt-connected by heat. In the case of P-LGA, when mounting on a printed wiring board, solder balls are heated and melted between the solder ball connection conductive pads formed on the motherboard printed wiring board surface and the solder ball conductive pads for P-LGA. Connect with

The metal plate used in the present invention is not particularly limited, but has a high elastic modulus and a high thermal conductivity and a thickness of 50 to 500 μm, preferably 100 to 400 μm. Specifically, pure copper, oxygen-free copper,
In addition, alloys containing 95% by weight or more of copper, such as Fe, Sn, P, Cr, Zr, and Zn, are preferably used. Further, a metal plate or the like in which the surface of the alloy is plated with copper may be used. A commonly known copper foil is used. Preferably, an electrolytic copper foil having a thickness of 3 to 18 μm is used.

The height of the metal truncated conical protrusion of the present invention is not particularly limited, but is preferably set to be 50 to 150 μm higher than the base metal plate. In addition, the thickness of the insulating layer such as prepreg is slightly lower than the height of the metal truncated conical protrusions, preferably 5 to 10 μm lower, and after lamination molding, resin is filled between the truncated conical protrusions and in the clearance holes or slit holes. Then, the tip of the truncated conical projection is brought into contact with and joined to at least a part of the surface copper foil by pressure.

The range in which the metal truncated cone-shaped protrusions are formed is substantially the same as the area of the semiconductor chip on the surface, and is generally within 5 to 20 mm square. 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. The strength is maintained so that the peel strength (ball shear strength) when a pressure is applied to the ball from the side can be maintained.

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

The polyfunctional cyanate compound which is a preferred thermosetting resin component of the present invention is a compound having two or more cyanato groups in the molecule. Specific examples include 1,3- or 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-, 1,8-, 2 , 6- or 2,7-
Dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4-dicyanatobiphenyl, bis (4-dicyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, 2,2- Bis (3,5-dibromo-4-cyanatophenyl) propane, bis (4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) sulfone, tris (4-cy (Anatophenyl) phosphite, tris (4-cyanatophenyl) phosphate, and cyanates obtained by reacting novolak with cyanogen halide. In addition to these,
8, 43-18468, 44-4791, 45-11712, 46-41112,
Polyfunctional cyanate compounds described in JP-A-47-26853 and JP-A-51-63149 can also be used. Further, the molecular weight of the polyfunctional cyanate compound having a triazine ring formed by trimerization of a cyanato group of
0-6,000 prepolymers are used. This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate ester monomer with a catalyst such as an acid such as a mineral acid or a Lewis acid; a base such as a tertiary amine such as sodium alcoholate; or a salt such as sodium carbonate. It can be obtained by: The prepolymer also contains some unreacted monomers and is in the form of a mixture of the monomer and the prepolymer, and such a raw material is suitably used for the purpose of the present invention. Generally, it is used after being dissolved in a soluble organic solvent.

As the epoxy resin, a generally known epoxy resin can be used. Specifically, liquid or solid bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin; butadiene, pentadiene, vinylcyclohexene, dicyclopentyl ether, etc. And polyglycidyl compounds obtained by reacting a polyol, a hydroxyl-containing silicone resin with an epohalohydrin, and the like. These may be used alone or in combination of two or more. A generally known polyimide resin can be used. Specific examples 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, economy and the like. It is preferable to use The amount used is 0.005 to 10 parts by weight, preferably 0.01 part by weight, per 100 parts by weight of the thermosetting resin.
~ 5 parts by weight.

As the glass cloth base material used as the reinforcing base material of the prepreg, generally known woven cloths and nonwoven cloths are used, but woven cloths are preferable in view of strength. In particular,
Known glass fiber cloths, such as E glass, S glass, and D glass, are mentioned. These may be mixed. In addition, examples of the organic substrate include generally known woven fabrics and nonwoven fabrics such as liquid crystal polyester fibers and wholly aromatic polyamide fibers.

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, a substrate is impregnated with a thermosetting resin composition and dried to obtain a semi-cured laminated material. The temperature for forming a semi-cured resin layer of the prepreg is generally 100 to 180 ° C. The time is 5 to 60 minutes, and is appropriately selected depending on the desired flow rate. The method for producing the metal core of the present invention and the printed wiring board for a semiconductor plastic package using the same is not particularly limited.
Method. (1) An etching resist (FIG. 1, b) is adhered to the entire surface of a metal plate (FIG. 1, a) serving as a metal core, and an etching resist (FIG. 1, b) is adhered to a position where a back frustum is formed. Further, the etching resist (FIG. 1, b) where the clearance hole is to be formed is removed. (2) Etching from both sides, a plurality of truncated conical projections (Fig. 1,
c) and a clearance hole (Fig. 1, d)
Is formed around it. A frusto-conical projection (FIG. 1, e) can also be formed around the front and back of the metal plate for a purpose different from the frusto-conical projection (c) for the purpose of displacement, dimensional shrinkage, etc. (FIGS. 2, (2-)). 2)). (3) On this back surface, a glass cloth base prepreg (Fig. 1,
f), a copper foil (FIG. 1, g) is placed outside the prepreg, a prepreg (FIG. 1, h) without a hollow is placed on the surface, and a second-stage bonding pad (FIG. 1) is placed thereon. , I) and other circuits (FIG. 1, j) formed on the double-sided copper-clad laminate (FIG. 1,
In step (k), the surface of the copper foil is subjected to a chemical treatment so that the circuit side faces inward. (4) Laminate under heat, pressure and vacuum to form a double-sided metal foil-clad multilayer board with a metal core (Fig. 1, l). (5) In the clearance hole, use a mechanical drill to prevent the metal core from coming into contact with the through hole.
Open m) and after desmearing, copper plating the whole. (6) The copper foil in the area of the surface semiconductor chip and the second-stage bonding pad (FIG. 2, n) is removed by etching, and the surface is sandblasted to the second-stage bonding pad (FIG. 2, n). The glass cloth substrate and the thermosetting resin composition are cut and removed. (7) Protect the area other than the semiconductor chip mounting area with metal sheet
After protection by o (FIG. 2, o), the metal core is ground again by the sand blast method to expose a flat inner metal core surface (p in FIG. 2) to be a semiconductor mounting portion. (8) After forming the circuit on the front and back, the exposed metal surface of the cavity, which becomes the semiconductor chip mounting portion on the surface,
The printed wiring board is prepared by coating the portions other than the bonding pads on the lower side and the solder ball pads on the back surface with a plating resist (t in FIG. 2) and attaching nickel plating and gold plating. A semiconductor chip (FIG. 2, q) is bonded and fixed to the semiconductor chip mounting portion (FIG. 2, p) of the printed wiring board with the exposed metal core with a thermally conductive adhesive (FIG. 2, r), and a bonding wire
(FIG. 2, s) is connected to the first and second bonding pads, sealed with a sealing resin (FIG. 2, u), and then solder ball (FIG. 2, v) to the solder ball pad (FIG. 2, v). 2, w) is melted and bonded and fixed to obtain a semiconductor plastic package.

[0028]

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 50μm thick
Impregnated into glass woven fabric, dried and gelled (at 170 ° C) 5
A semi-cured prepreg B having an insulating layer thickness of 75 μm was prepared so that the resin flow was 10 mm in 5 seconds at 170 ° C., 20 kgf / cm ² for 5 seconds.

On the other hand, Cu: 9 having a thickness of 300 μm serving as an inner metal plate
Prepare an alloy plate of 9.9%, Fe: 0.07%, P: 0.03%, and
Form a liquid etching resist of 5μm, size 50
On the diametrically opposite surface within the 15 mm square of the part where the semiconductor chip is mounted in the center of the package area of the mm square, 400 circular resists of 250 μm are left, and the surface of this part is created in order to create a clearance with a hole diameter of 0.6 mm. Remove the etching resist,
Etching from both sides, height 153μm on the back, bottom diameter
400 frusto-conical protrusions with 645 μm and upper diameter of 110 μm were formed, and a clearance hole with a hole diameter of 0.6 mm was formed around it (Fig. 1,
2).

On the other hand, 18 μm of the prepreg B
m electrolytic copper foil placed, 200 ℃, 20kgf / cm ² , lamination molding for 2 hours to make a double-sided copper-clad laminate, forming a second-stage bonding pad and other circuits on this one side, After the black copper oxide treatment, the circuit was placed so that the circuit side faced inside. In addition, on the back surface, two prepregs B, each having a hole slightly larger than the truncated cone-shaped metal projection formed on the opposite surface of the semiconductor chip mounting portion, are placed, and an 18 μm electrolytic copper foil is arranged outside thereof. Similarly, they were laminated and integrated.

A through hole having a hole diameter of 0.25 mm was formed in the clearance hole with a mechanical drill, and after desmearing, the whole was electrolessly and electrolytically plated with 20 μm copper. The copper foil on the surface of the semiconductor chip mounting portion and the area of the second-stage bonding wire is removed by etching, and the glass cloth base material and the thermosetting resin composition are sand-blasted from the surface to the second-stage bonding wire. Cutting removed. Then, a metal protective sheet is put on the semiconductor chip mounting portion, and the glass cloth base material and the thermosetting resin composition are cut and removed again by the sandblasting method until the metal core is reached. After the removal, a circuit was formed on the front and back surfaces. The solder ball pad on the back was created avoiding the truncated cone. A plating resist was formed on portions other than the semiconductor chip mounting portion, the wire bonding portion, and the ball pad portion on the back surface, and nickel and gold plating were performed thereon to complete a printed wiring board. A 13 mm square semiconductor chip is bonded and fixed with a silver paste on the flat inner metal core, which is the mounting surface of the semiconductor chip, and then the semiconductor chip and the first and second stage bonding pads are wire-bonded, then silica Semiconductor chips, wires, and bonding pads were resin-encapsulated using a liquid resin for epoxy encapsulation, 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. The evaluation results are shown in Tables 1, 2 and 3.

Comparative Example 1 Two prepregs B (FIG. 3, h) of Example 1 were used, and 12 μm electrolytic copper foils (FIG. 3, g) were arranged on the upper and lower sides at 200 ° C. and 20 kgf / c.
Lamination molding was performed for 2 hours under a vacuum of m ² and 30 mmHg or less to obtain a double-sided copper-clad laminate. 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 (t in FIG. 3) and then plated with nickel and gold. This has a through hole for heat dissipation formed at the place where the semiconductor chip (FIG. 3, q) is mounted, and the semiconductor chip is bonded thereon with a silver paste (FIG. 3, r), and wire bonding (FIG. 3, FIG. s) After that, resin sealing was carried out using an epoxy resin sealing compound (FIG. 3, u) in the same manner as in Example 1, and solder balls (FIG. 3, w) were joined. Similarly joined to the motherboard. The evaluation results are shown in Tables 1, 2 and 3.

Comparative Example 2 300 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 produce a no-flow prepreg (prepreg C) having a gelling time of 10 seconds and a resin flow of 98 μm, and a high-flow prepreg (prepreg D) having a gelling time of 150 seconds and a resin flow of 18 mm. Using two prepregs D, 190 ℃, 20kgf / 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, and the semiconductor chip mounting portion was cut out using a counterbore machine, and a copper plate having a thickness of 200 μm was formed on the back surface (FIG. 4, a).
Was bonded in a similar manner under heat and pressure using a punched-out Noflow prepreg C to prepare a printed wiring board with a heat sink. This slightly warped.
Semiconductor chips (Fig. 4, q) with silver paste directly on this heat sink
And bonded by wire bonding, and sealed with a liquid epoxy resin (FIG. 4, u). Similarly, it was joined to a motherboard printed wiring board. The evaluation results are shown in Tables 1, 2 and 3.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

<Measurement method> 1) Ball shear strength A solder ball is attached to a ball pad having a diameter of 0.65 mm.
The strength when peeling by pushing 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 before measuring the package temperature.

[0039]

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 a surface of the printed wiring board on which a semiconductor chip is mounted is provided.
It is a cavity type, the metal core is exposed,
At least one semiconductor chip is bonded and fixed to this surface with a heat conductive adhesive, and the circuit conductor and the semiconductor chip are connected by wire bonding. On the opposite surface of the printed wiring board, a truncated cone from an inner metal core is formed. The protrusions are in contact with the surface copper foil, and the circuit conductors connected to the protrusions or the circuit conductor pads that connect the package to the outside with solder balls are connected to at least the surface circuit conductors and the metal plate by heat. In a printed circuit board for a ball grid array type semiconductor plastic package having a structure in which at least a semiconductor chip, a wire, and a bonding pad are resin-sealed by connecting with a through-hole conductor insulated by a curable resin composition, The surface of the metal plate on which the semiconductor chip is mounted is flat, and the opposite surface is Forming a projection, forming a clearance hole or a slit hole at a location other than the semiconductor chip mounting portion and the truncated cone-shaped projection, and then applying a glass cloth base material prepreg on a flat surface of a metal plate which is a mounting surface of the semiconductor chip. A double-sided copper-clad laminate with a single-sided circuit on which a circuit to be used as a second-stage bonding pad and other circuits are formed is disposed on the outside thereof, and the circuit side faces inward. Using a double-sided copper-clad multilayer board obtained by placing a glass cloth base prepreg with a hole slightly larger than the truncated conical projection, placing a copper foil on the outside, heating, pressing, laminating under vacuum, In the center of the clearance hole or slit hole, make a small through hole for through hole so as not to contact the metal core, apply copper plating after desmearing, and mount the semiconductor chip on the surface And grinding the copper foil, glass cloth base material and thermosetting resin composition on the surface to be the second-stage bonding pad portion by sandblasting or the like until the second-stage bonding pad is exposed, After protecting the second-stage bonding pad portion with a protective metal sheet, a resist, etc., the metal core is exposed by cutting and removing the metal core again by a sandblasting method or the like, and thereafter, a circuit is formed on both sides, and at least a semiconductor chip is formed. Provided is a printed wiring board with a metal core obtained by covering portions other than a mounting portion, a wire bonding portion, and a ball pad portion with a plating resist and performing nickel plating and gold plating. ADVANTAGE OF THE INVENTION According to this invention, the printed wiring board which is excellent also in the adhesive strength with a solder ball, there is no moisture absorption from the lower surface of a semiconductor chip, and the heat resistance after moisture absorption, ie, popcorn phenomenon, is improved significantly. By using a polyfunctional cyanate ester resin composition as the thermosetting resin composition, it has excellent insulation properties after pressure cooker treatment, excellent migration resistance, and is also suitable for mass productivity,
A printed wiring board for a semiconductor plastic package having a novel structure with improved economic efficiency was obtained.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a semiconductor plastic package using a printed wiring board for a ball grid array with a metal core according to the present invention.

FIG. 2 is a manufacturing process diagram of a semiconductor plastic package using a ball grid array type printed wiring board with a metal core according to the present invention.

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

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

[Explanation of symbols]

a metal plate b etching resist c frusto-conical projection formed in package d clearance hole e frusto-conical projection formed outside package f prepreg B with holes formed g copper foil h prepreg B without holes formed Second-stage bonding pad formed on double-sided copper-clad laminate j Inner-layer circuit formed on double-sided copper-clad laminate k Double-sided copper-clad laminate l Double-sided copper-clad multilayer board with metal core m Through hole for front / back circuit conduction n Second-stage bonding wire o Metal protection sheet p Inner layer metal core exposed part as semiconductor mounting part q Semiconductor chip r Heat conductive adhesive s Bonding wire t Plating resist u Sealing resin v Solder ball pad w Solder ball x Heat Through hole for radiation y Prepreg C

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuji Komatsu 6-1-1, Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas Chemical Co., Ltd. Tokyo factory F-term (reference) 5E315 AA05 BB01 BB14 CC16 DD15 DD16 DD17 DD20 DD25 GG01

Claims (4)

[Claims] 1. A printed wiring board in which a surface on which a semiconductor chip is mounted is flat on a part of the printed wiring board in a thickness direction, and a plurality of truncated metal conical protrusions are connected to a metal foil on a back surface on an opposite surface. A semiconductor chip is fixed on a metal plate having a size substantially the same as that of the printed circuit board, and on one side of the printed wiring board, a metal plate lower than a circuit including bonding pads formed in two steps around the semiconductor chip. The signal transmission circuit conductor on the surface of the printed wiring board is insulated from the signal transmission circuit conductor by a thermosetting resin composition, and the signal transmission circuit conductor and the semiconductor chip are connected in both stages by wire bonding. 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 metal plate and a resin composition insulated. A printed wiring board used for a ball grid array type semiconductor plastic package having a structure connected by through-hole conductors. First, the metal plate serving as a metal core has a flat surface on which the semiconductor chip is mounted, and a plurality of A glass cloth base thermosetting resin prepreg is placed on a flat surface of a metal plate in which a clearance hole or a slit hole is formed at a place other than the semiconductor chip and the truncated cone-shaped projection, and further placed thereon. A double-sided copper-clad laminate with a single-sided circuit formed with a circuit serving as a second-stage bonding pad and an inner-layer circuit is arranged so that the circuit side is on the inside, and the opposite surface having a truncated conical metal protrusion is
Using a double-sided copper-clad multilayer board obtained by laminating a glass cloth base prepreg with a slightly larger area than the projection surface, placing a copper foil on the outside, heating and pressing under pressure, and using a clearance hole or slit At the center of the hole, a through hole is formed so as not to come into contact with the metal core, copper-plated, and a copper foil, a base material and a resin on the surface where the semiconductor chip is to be mounted and the second-stage bonding pad portion The layer is removed to expose the second stage bonding pads for mounting the semiconductor chip, and then the inner layer metal core is also exposed, and the first stage bonding pads and circuits are formed on the surface,
Copper foil, on the back side of which a frusto-conical metal protrusion contacts, is formed as a solder ball pad and circuit for connecting solder balls for heat radiation, and at least the semiconductor chip mounting portion, wire bonding pad portion and solder ball pad portion are plated with noble metal. The obtained printed wiring board for a ball grid array type plastic package containing a metal core, in which wire bonding pads are formed in two stages. 2. A method for exposing a second-stage bonding pad and a metal core for mounting a semiconductor chip, after removing the surface copper foil, removing the surface thermosetting resin composition and the glass cloth layer by sandblasting. Grinding to the inner layer second bonding pad, exposing the second bonding pad, covering the second bonding pad portion, further sandblasting the inner metal core to the resin layer and glass cloth substrate The printed wiring board for a semiconductor plastic package containing a metal core according to claim 1, wherein the printed wiring board is formed by cutting and removing a layer. 3. The printed wiring board for a ball grid array type semiconductor plastic package with a metal core according to claim 1, wherein the metal plate is a copper alloy containing 95% by weight or more of copper or pure copper. 4. The thermosetting resin according to claim 1, wherein said thermosetting resin is a polyfunctional cyanate ester and a thermosetting resin composition containing said cyanate ester prepolymer as an essential component.
A printed wiring board for a ball grid array type semiconductor plastic package containing a metal core according to 1, 2, or 3.