JP2000315750A - Manufacturing method of ball grid array type printed wiring board excellent in heat dissipation - Google Patents

Abstract

(57) [Problem] To provide a method for manufacturing a printed wiring board which is excellent in heat dissipation, popcorn phenomenon, mass productivity, etc. in the printed wiring board. SOLUTION: A plurality of truncated cone-shaped projections are provided at positions directly opposite to a surface on which a semiconductor chip is mounted on a double-sided copper-clad laminate,
Circuits are formed in other places, then prepregs and copper foils with hollowed out truncated conical protrusions are placed, and after lamination molding, the surface copper foil, organic base material, and resin are cut to expose the metal surface. Create a cavity type printed wiring board. Further, a polyfunctional cyanate resin composition is used as the thermosetting resin composition. [Effect] A ball grid array with a novel structure that is excellent in connectivity between the inner metal plate and the outer metal foil layer on the back, heat dissipation, electrical insulation after pressure cooker, migration resistance, etc., and suitable for mass productivity. The printed wiring board used for the mold semiconductor plastic package was obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

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

[0003]

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

[0004]

That is, according to the present invention, a double-sided copper-clad laminate having a flat upper surface and a truncated-cone-shaped projection and a circuit on the lower surface is prepared, and if necessary, subjected to a chemical treatment.
On the lower surface, a frusto-conical projection portion, a prepreg in which a hollow portion is slightly larger than its area is arranged, a copper foil is overlaid on the outside thereof, heated, pressed, preferably laminated and formed under vacuum, and then integrated. , Through-holes for through-holes are formed, plated through-holes, then heat-dissipating solder ball pads and their connection circuits are formed on the copper foil in contact with the frusto-conical projections on the back, and the copper foil is removed from the surface Thereafter, the glass cloth base material and the thermosetting resin composition layer are preferably ground and removed by a sand blast method, and only the semiconductor chip mounting portion is subjected to a sand blast method or the like to the inner surface metal plate and the glass cloth base material and the thermosetting. After removing the conductive resin layer to expose the flat surface of the copper foil having a truncated conical shape on the back surface, at least the semiconductor chip mounting portion, the wire bonding pad portion, and the solder ball pad portion have noble metal. Plated to provide a method of creating a printed wiring board.

Using this printed wiring board, a semiconductor chip is bonded and fixed to the surface of the metal plate in the cavity with a thermally conductive adhesive, and after wire bonding, sealing is performed with a sealing resin, and then a solder ball is melt-connected to the back surface. Semiconductor plastic package.

The obtained semiconductor plastic package is excellent in thermal conductivity, does not absorb moisture from the lower surface of the semiconductor chip, and has greatly improved heat resistance after absorbing moisture, ie, the popcorn phenomenon, and is suitable for mass production. Thus, a method of manufacturing a semiconductor plastic package having a novel structure with improved economy is provided. Further, by using a polyfunctional cyanate composition as a thermosetting resin, a method for producing a semiconductor plastic package having a novel structure, which is excellent in electric insulation properties and migration resistance after a pressure cooker, is provided. .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a semiconductor plastic package using a printed wiring board manufactured according to the present invention, a surface on which a semiconductor chip is mounted is flat in a part of the printed wiring board in a thickness direction, and a diametrically opposite surface is provided. A metal plate of the same size as the printed wiring board, in which a plurality of truncated cone-shaped metal protrusions are connected to the surface copper foil on the back side, is located lower than the circuit including the bonding pads around the surface of the printed wiring board. The surface that fixes the semiconductor chip on the metal plate that is
A metal plate is exposed in the form of a cavity, and at least one semiconductor chip is fixed on this surface with a heat conductive adhesive, and the circuit conductor and the semiconductor chip are connected by wire bonding to form a printed wiring. On the opposite side of the board, a truncated conical projection from the inner metal plate is in contact connection with the surface copper foil, and a circuit conductor formed by connecting from this projection or the package is connected to the outside with solder balls. A ball grid array type semiconductor plastic package having a structure in which the formed circuit conductor pad is connected to at least a signal propagation circuit conductor on the surface and a through hole conductor, and at least a semiconductor chip, a wire, and a bonding pad are resin-sealed. .

The method for manufacturing a printed wiring board according to the present invention comprises the following steps. a. The metal plate and copper foil are placed on both sides of the glass cloth base thermosetting resin prepreg, and the metal plate exposed on one side of the metal foil-clad laminate is etched, and the semiconductor chip mounting portion of the metal plate is etched. Forming a trapezoidal projection on the opposite surface of the region, b. Forming a plurality of truncated cone-shaped projections on the trapezoidal projection, and forming a circuit around the trapezoidal projection, c. Overlap the glass cloth base prepreg with a slightly larger area than the frustoconical metal projection surface in the area excluding, place the copper foil on the outside, heat, under pressure, preferably under vacuum, laminate molding on both sides A step of creating a copper-clad multilayer board, d. Forming a through-hole for a through-hole at a position other than the truncated conical protrusion, applying copper plating, and at least a copper foil on a surface mounting a semiconductor chip, The glass cloth substrate and the resin layer are preferably Removing by a blast method to expose a metal surface to be a semiconductor chip mounting portion; e. Forming a bonding pad and a signal propagation circuit on a surface around a region to be a semiconductor chip mounting portion, and A step of forming a solder ball pad and a circuit for connecting the copper foil where the frustoconical metal projection contacts the surface copper foil to the solder balls for heat dissipation; f. At least a semiconductor chip mounting portion, a wire bonding pad portion and a solder ball pad portion Process of precious metal plating.

There is no particular limitation on the method of forming the cavities serving as the semiconductor chip mounting portions on the double-sided copper-clad laminate, but preferably, the copper foil on the semiconductor chip mounting portions is removed, and then the base material and the heat sink are removed. It is prepared by cutting and removing the curable resin composition by a sand blast method. When producing a printed wiring board, circuits may be formed on the front and back surfaces before cutting by the 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 precious metal plating, it is also possible to perform precious metal plating on the whole, and then to cover unnecessary portions with a permanent protection resist.

In a known method of fixing a semiconductor chip on the upper surface of a metal-core printed wiring board having a through hole, heat from the semiconductor chip is dropped to a heat-dissipating through hole immediately below, similarly to a conventional P-BGA package. Heat must be dissipated and the popcorn phenomenon cannot be improved. Since the present invention does not adopt a shape in which a through hole is formed below a semiconductor chip mounting surface, there is no moisture absorption from the back surface, the popcorn phenomenon is extremely unlikely to occur, and a method of manufacturing a semiconductor plastic package excellent in heat dissipation. Can be provided.

The method of forming the metal plate of the present invention is not particularly limited. For example, first, a metal plate and a copper foil are arranged and laminated on both sides of a prepreg of a glass cloth base material impregnated with a thermosetting resin. Using a metal foil-clad laminate, leave the etching resist on this one side, that is, the entire area of the exposed metal plate where the frustoconical metal projections are formed and the opposite side of the metal foil,
The metal plate in the area where the trapezoidal frustoconical metal protrusion is formed by etching from both sides is left in a convex shape. After peeling off the plating resist, the entire surface is again covered with the plating resist. On the front surface, if a second-stage bonding pad portion is required, a circuit on which the bonding pad is formed is formed. The etching resist is left in a circular shape with a small diameter on the trapezoidal portion on the metal plate where the pattern is to be formed, and the other portions are etched so as to form a circuit, thereby forming a truncated conical projection and creating a circuit. In this case, the size of the truncated cone-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 double-sided metal-clad laminate having the truncated cone-shaped protrusions and the circuit formed on both sides 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. On the back side subjected to the surface treatment, a glass cloth base material prepreg in which holes are slightly larger than the area of the truncated cone-shaped projection portion is disposed so as to be slightly lower than the height of the trapezoidal projection after lamination molding, and the Lay the copper foil on the outside, heat and press, preferably laminate under vacuum, and cut the frustoconical metal protrusion tip into the copper foil on the surface layer or make it come into strong contact and join together, then double-sided copper clad Create a multilayer board. In this case, 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.

When a through hole for a through hole is formed in the obtained double-sided copper-clad multilayer board with a mechanical drill, a laser, or the like, and when a place for mounting a semiconductor chip is formed independently of a surrounding metal foil, In order to use the surrounding metal foil as a circuit, a hole is made so as to partially contact the metal, and through-hole plating is performed. If the metal part on which the semiconductor chip is mounted is connected to the surrounding metal,
Drill holes so that they do not come into contact with metal, and copper-plate the whole. On the back surface, a ball pad is formed so as to avoid the portion where the tip of the truncated cone-shaped projection is in contact with the surface copper foil or to avoid the portion. 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 is cut and removed using a counterbore processing, sandblasting method, etc. to remove the copper foil on the semiconductor chip, the glass cloth base material and the thermosetting resin to the inner metal plate, exposing the metal plate to create a cavity type substrate. I do. After forming the circuit on the front and back, at least the bonding pad portion and the solder ball pad portion on the back surface are covered with a plating resist, and nickel and gold plating is performed to produce a printed wiring board. When producing a printed wiring board, circuits may be formed on the front and back surfaces before cutting by the sandblast method. In this case, the front and back circuits are covered with a protective resist or a protective metal before sandblasting. Further, in the case of noble metal plating, the whole can be plated with noble metal, and then unnecessary portions can be covered with a permanent protective film. Thereafter, the semiconductor chip is bonded and fixed to the semiconductor chip mounting portion on the front surface with a thermally conductive adhesive, wire-bonded, and resin-sealed, and the back surface is melt-connected with a solder ball to form a semiconductor plastic package. Then, the solder ball pad portion on the back surface is joined to the motherboard printed wiring board with solder balls. The heat generated from the semiconductor chip conducts heat from the semiconductor chip mounting portion and then to the solder ball pad through the metal truncated conical protrusion on the opposite surface of the metal plate,
Diffusion to motherboard printed wiring boards joined by solder balls.

The side surface of the metal plate may be either in the form of being embedded with the thermosetting resin composition or in the form of being exposed, but the thermosetting resin composition is preferred in terms of preventing rust and the like. It is more preferable that it is coated with.

When the semiconductor chip mounting portion of the metal plate is connected to the surrounding metal plate, the through-hole for conducting 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.

As the sand brass method, generally known ones can be used. Specific examples include a dry type air blast method, a shot blast method, and a wet type wet blast method. The powder to be used is appropriately selected, but preferably, a known powder such as silica sand or glass powder of 20 μm or less can be used. The pressure is not particularly limited, but is generally from 0.1 to 0.5 MPa.

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

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

A solder ball is connected to a 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 fused by heat. PLGA
In the case of mounting on a printed wiring board, a solder ball connection conductive pad and a P-LGA solder ball conductive pad formed on the motherboard printed wiring board surface,
The solder balls are connected by heating and melting.

The metal plate (also referred to as metal foil or copper foil) used in the present invention is not particularly limited, but has a high elastic modulus and a high thermal conductivity, and preferably has a thickness of 100 to 400 μm. Specifically, pure copper, oxygen-free copper, other copper, 95% by weight or more Fe, S
Alloys with n, P, Cr, Zr, .Zn and the like 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 frustoconical projection of the present invention is not particularly limited, but is preferably set to be 50 to 150 μm higher than the metal surface of the base. Also, the thickness of the insulating layer such as prepreg is slightly lower than the height of the metal truncated conical protrusion after lamination molding, preferably 5 to 10 μm lower, after lamination molding, the frustoconical protrusion, between the circuit, and clearance The hole or slit hole is filled with a resin, and the tip of the truncated conical projection is brought into contact with and joined to at least a part of the surface copper foil.

The range in which the metal truncated cone-shaped protrusions are formed is around the area of the semiconductor chip on the surface, and generally within 5 to 20 mm square. Preferably, a ball pad is formed avoiding a portion of the copper 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 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,
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, generally known epoxy resins 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 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 hole formed in the metal plate is slightly larger than the diameter of the through hole for front / back conduction. Specifically, it is preferable that a distance of 50 μm or more between the through hole wall and the metal plate clearance hole or the slit hole wall is insulated by the thermosetting resin composition. The diameter of the through hole for front / back conduction is not particularly limited, but is preferably 50 to 300 μm.

When preparing a prepreg for a printed wiring board of the present invention, a substrate is impregnated with a thermosetting resin composition and dried to obtain a semi-cured laminated material. 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 plate of the present invention and the printed wiring board for a semiconductor plastic package using the same is not particularly limited, but for example, the following method (FIGS. 1 and 2). (1) Glass cloth substrate with a metal plate (Figure 1, a) exposed on one side
(FIG. 1, b) A double-sided metal foil-clad laminate is prepared. (2) An etching resist is adhered to the entire surface, and the entire surface is formed on one side of the metal plate at the position where the truncated conical projection is formed and on the opposite side of the metal foil. The etching resist is left and etched partway to form a trapezoidal projection (FIG. 1, c) on the opposite side of the central part of the semiconductor chip mounting area, and a metal plate, which is lower than the projection, around the periphery, that is, After leaving the metal foil and removing the plating resist,
(3-1) Attach plating resist to the whole surface again, leave a small diameter circular resist at the place where a plurality of truncated conical protrusions are formed on the trapezoidal protrusion, leave the resist at the place where the circuit is formed, and etch Then, a substrate having a single-sided circuit (FIG. 1, e) having a truncated conical projection (FIG. 1, d) at the center of one side of the printed wiring board is prepared, and the surface of the metal foil is subjected to black copper oxide treatment. In this case, when the metal foil portion having the truncated cone-shaped metal protrusion is viewed from below, the semiconductor chip mounting portion having the truncated cone-shaped protrusion on the back surface at the center is separated from the metal foil on which the surrounding circuit is formed. Shape (3-2; f). (4) On this back surface, a glass cloth base material prepreg (FIG. 1, g) which is slightly larger than the central metal protrusion area is arranged, and a copper foil (FIG. 1, h) is arranged outside thereof. (5) Laminate molding under heat, pressure and vacuum to produce a double-sided copper-clad multilayer board (FIG. 1, i). (6) Drill holes for through-holes (k in Fig. 2) for conducting the front and back circuits with a mechanical drill, copper plating the whole after desmearing, and first remove the copper foil on the semiconductor chip mounting part on the surface by etching. Then, from the surface side, the glass cloth base material and the thermosetting resin composition on the surface were cut and removed by a sand blast method to a metal surface (FIG. 2, j) serving as a semiconductor mounting portion, and (7) after forming a circuit on both sides, Except for the semiconductor chip mounting portion on the front surface, the bonding pad portion, and the solder ball pad portion on the back surface, a plating resist (FIG. 2, p) was coated, and nickel plating and gold plating were applied to prepare a printed wiring board. A semiconductor chip (FIG. 2, l) is bonded and fixed to the semiconductor chip mounting portion of the printed wiring board with the metal plate exposed by a heat conductive adhesive (FIG. 2, m) and a bonding wire (FIG. 2, n). After connection and sealing with a sealing resin (FIG. 2, o), a solder ball (FIG. 2, q) is melted and adhered and fixed to a solder ball pad to obtain a semiconductor plastic package.

[0033]

The present invention will be specifically described below with reference to examples and comparative examples. Unless otherwise specified, “parts” indicates parts by weight. Example 1 900 parts of 2,2-bis (4-cyanatophenyl) propane and bis (4-
100 parts of (maleimidophenyl) methane are melted at 150 ° C,
The mixture was reacted for 4 hours with stirring to obtain a prepolymer. This was dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. Add bisphenol A type epoxy resin (trade name: Epicoat 1001, Yuka Shell Epoxy Co., Ltd.)
) And 600 parts of a cresol novolac type epoxy resin (trade name: ESCN-220F, manufactured by Sumitomo Chemical Co., Ltd.) were uniformly mixed and dissolved. Further, as a catalyst, zinc octylate 0.4
Was added and dissolved and mixed. To this, 500 parts of an inorganic filler (trade name: calcined talc, manufactured by Nippon Talc Co., Ltd.) was added, and uniformly mixed by stirring to obtain Varnish A. This varnish is impregnated with a 50 μm thick glass woven fabric, dried, and gelled (at 170 ° C.) 50 seconds, 170
A prepreg B in a semi-cured state with a thickness of 88 μm of an insulating layer, which was formed so that the resin flow was 8 mm at 5 ° C., 20 kgf / cm ² and 5 minutes.

On the other hand, using this prepreg B, 18
μm electrolytic copper foil, put 105μm electrolytic copper foil on one side, 200
Laminate molding was performed at 20 ° C. and 20 kgf / cm ² for 2 hours to obtain a double-sided copper-clad laminate. An etching resist with a thickness of 25 μm is attached to the entire surface, the etching resist is left entirely on the 18 μm copper foil side, the resist is left on the 105 μm side to form a frustoconical projection, and etched to form a trapezoidal projection on one side A double-sided copper-clad laminate having (c) was obtained [FIG. 1- (2)]. After removing the resist, apply a liquid etching resist to the entire surface again.
μm, leaving 400 pieces of 250 μm circular resist on the diametrically opposite surface within the 15 mm square of the part where the semiconductor chip is mounted in the center of the 50 mm square package area, around which there is a circuit for forming circuits. The resist is etched and etched, and 400 frustoconical protrusions (d) with a height of 85 μm from the base copper foil, a bottom diameter of 507 μm, and a top diameter of 180 μm are placed around the circuit.
(e) was formed [FIG. 1- (3-1)]. The copper foil serving as the semiconductor mounting portion having the truncated-cone-shaped protrusion on the back surface had a shape (f) separated from the surrounding copper foil for circuit formation.

After subjecting the copper foil surface to a black copper oxide treatment, one prepreg B (g) having a hole slightly larger than the area of the truncated cone-shaped metal projection (d) is placed on the back surface, and Place 18μm electrolytic copper foil (h), similarly laminate molding,
This was integrated to obtain a double-sided copper-clad multilayer board (i).

A through hole having a hole diameter of 0.25 mm is drilled with a mechanical drill, and after desmearing, the entire surface is plated with 20 μm copper by electroless and electrolytic copper plating to form a through hole conductor (k).
Was formed. After etching and removing the copper foil on the semiconductor chip mounting portion, the glass cloth base material and the thermosetting resin composition are cut and removed from the surface by sandblasting until reaching the metal surface, and the surface is sandblasted through a soft etching process. After removing the components, circuits were formed on the front and back surfaces.
The solder ball pad on the back was created avoiding the truncated cone. A plating resist (p) 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 to complete a printed wiring board. A 13 mm square semiconductor chip (l) is silver-pasted on a flat inner metal plate, which is the mounting surface of the semiconductor chip.
After bonding and fixing with (m), wire bonding is performed, and then the semiconductor chip (l), wires (n) and bonding pads are resin-sealed using a silica-containing epoxy sealing liquid resin (o), and The semiconductor package was prepared by joining the solder balls (q). 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 and 2.

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

Comparative Example 2 300 parts of epoxy resin (trade name: Epicoat 5045, manufactured by Yuka Shell Epoxy Co., Ltd.) and epoxy resin (trade name: E
SCN220F, manufactured by Sumitomo Chemical Co., Ltd.) 700 parts, dicyandiamide 35 parts, 2-ethyl-4-methylimidazole 1 part are dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide, and this is dissolved in a 100 μm thick glass woven fabric. Impregnation and drying were performed to produce a no-flow prepreg (prepreg C) having a gelling time of 10 seconds and a resin flow of 98 μm, and a high-flow prepreg (prepreg D) having a gelling time of 150 seconds and a resin flow of 18 mm. Using two prepregs D, 190 ° C, 20kgf / cm ²
Laminate molding was performed for 2 hours under a vacuum of 30 mmHg or less to prepare a double-sided copper-clad laminate. Thereafter, a printed wiring board was prepared in the same manner as in Comparative Example 1, the semiconductor chip mounting portion was cut out with a counterbore machine, and a copper plate having a thickness of 200 μm on the back surface was punched out of the no-flow prepreg D. 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. The evaluation results are shown in Tables 1 and 2.

[0039]

[Table 1]

[0040]

[Table 2]

<Measurement method> 1) Ball shear strength A solder ball was attached to a ball pad having a diameter of 0.65 mm.
The strength at the time of pushing from the side and peeling was measured. 2) Heat resistance after moisture absorption A) JEDEC STANDARD TEST METHOD A113-A LEVEL3: 30 ℃ ・ 60%
After the treatment with RH for a predetermined time, the presence or absence of an abnormality in the substrate after three cycles of reflow soldering at 220 ° C. was confirmed by cross-sectional observation and electrical check. 3) Heat resistance after moisture absorption B) JEDEC STANDARD TEST METHOD A113-A LEVEL2: 85 ℃ ・ 60%
After processing at RH for a predetermined time (Max. 168 hrs.), The presence or absence of abnormality in the substrate after three cycles of reflow soldering at 220 ° C. was confirmed by cross-sectional observation and electrical check. 4) Insulation resistance value after pressure cooker treatment A comb-shaped pattern between terminals (line / space = 70/70 μm) was created, and the prepregs used were placed on each of these patterns. After treatment for a predetermined time at atmospheric pressure, post-treatment was performed at 25 ° C. and 60% RH for 2 hours, and insulation resistance between terminals was measured 60 seconds after 500 VDC was applied. 5) Migration resistance The test piece of 4) was applied at 85 ° C. and 85% RH at 50 VDC, and the insulation resistance between the terminals was measured. 6) Glass transition temperature Measured by the DMA method. 7) Heat dissipation The package was bonded to the same motherboard printed wiring board with solder balls and used continuously for 1000 hours, and then the temperature of the package was measured.

[0042]

According to the present invention, a metal plate and a copper foil are impregnated with a thermosetting resin, and are preferably exposed on one side of a metal-clad laminate, which is preferably disposed on both sides of a glass cloth substrate prepreg and laminated. The trapezoidal projection is formed by removing the periphery of the metal plate while leaving a part of it, and a plurality of truncated cone-shaped metal projections and circuits are formed, and the prepreg whose area is slightly larger than the truncated cone-shaped projection area is layered. Then, a copper foil is placed on the outside and laminated under heat, pressure and vacuum to form a double-sided copper-clad laminate. Then, a through hole for a through hole is formed in a portion other than the semiconductor chip mounting portion and a truncated conical protrusion on the opposite surface, copper plating is performed after desmear treatment, and the surface copper foil to be the semiconductor chip mounting portion on the surface is removed. Preferably, the metal plate is exposed by grinding and removing the base material and the thermosetting resin composition by a sand blast method, and thereafter forming a circuit on the front and back, at least a portion other than the semiconductor chip mounting portion, the wire bonding portion and the ball pad portion. This is a method of producing a printed wiring board by coating with a plating resist and performing nickel plating and gold plating. ADVANTAGE OF THE INVENTION According to this invention, it is excellent also in the adhesive strength with a solder ball, there is no moisture absorption from the lower surface of a semiconductor chip, the heat resistance after moisture absorption, that is, the popcorn phenomenon can be largely improved, and it is also suitable for mass production. The present invention also provides a method of manufacturing a printed wiring board for a semiconductor plastic package having a novel structure with improved economic efficiency. Further, by using a polyfunctional cyanate ester resin composition as the resin, a method for producing a printed wiring board for a semiconductor plastic package having excellent insulation and migration resistance after pressure cooker treatment is provided.

[Brief description of the drawings]

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

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

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

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

[Explanation of symbols]

a metal plate b glass cloth base thermosetting resin layer c trapezoidal projection d frustoconical projection e circuit f diagram in which semiconductor chip mounting part and surrounding circuit are separated g prepreg Bh with truncated frustoconical projection Foil i double-sided copper-clad multilayer board j semiconductor chip mounting metal exposed part k front and back circuit conduction through hole l semiconductor chip m silver paste n bonding wire o sealing resin p plating resist q solder ball r heat dissipation through hole s prepreg Ct copper plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/12 F (72) Inventor Katsuji Komatsu 6-1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas F-term (reference) in the Tokyo Chemical Works 4J043 PA02 PA04 QC14 RA08 RA47 SA13 SB01 TB01 UA131 UA132 UA352 UB012 UB021 ZB50 5E336 AA04 AA08 BB16 BB19 BC12 BC15 BC26 BC34 CC32 CC36 CC43 CC58 EE05 EE08 GG05 5A03 A11 BB05 BB19 BB22 BB28 CD01 CD32 EE02 EE32

Claims (4)

[Claims] 1. A printed wiring board having a flat surface on which a semiconductor chip is mounted and a plurality of truncated metal conical protrusions connected to a copper foil on the back surface on the diametrically opposite surface.
A metal plate approximately the same size as the printed wiring board is arranged, and a semiconductor chip is fixed on a metal plate lower than a circuit including bonding pads around the surface of the printed wiring board. Insulate the signal transmission circuit conductor with the thermosetting resin composition, and at least the signal transmission circuit conductor on the surface of the printed wiring board and the circuit conductor or the package formed on the opposite surface of the printed wiring board with the outside with solder balls. In a method of manufacturing a printed wiring board used for a ball grid array type semiconductor plastic package having a structure in which a circuit conductor pad formed for connection is connected to a through-hole conductor, a printed wiring board comprising the following steps: Manufacturing method, a. Metal foil-clad laminates with metal plate and copper foil placed and laminated on both sides of glass cloth base thermosetting resin prepreg Forming a trapezoidal projection on the opposite side of the area of the metal plate where the semiconductor chip is to be mounted by etching the metal plate exposed on one side of the b. A step of forming a circuit around the protrusion, c. A glass cloth substrate prepreg having a slightly larger area than the surface of the truncated cone-shaped metal protrusion is placed on the circuit, and a copper foil is placed on the outside of the prepreg, followed by heating and heating. A step of forming a double-sided copper-clad multilayer board by laminating under pressure, d. Forming a through-hole for a through-hole at a position other than the truncated conical protrusion, applying copper plating, and mounting a semiconductor chip on at least the surface Removing the copper foil, glass cloth base material, and resin layer on the portion to expose the metal surface to be the semiconductor chip mounting portion; e. Bonding pads and the like on the surface around the region to be the semiconductor chip mounting portion Form a circuit for signal propagation A step of forming a solder ball pad and a circuit for connecting the copper foil at the place where the truncated conical metal projection contacts the surface copper foil on the opposite surface to the solder ball for heat dissipation; f. At least a semiconductor chip mounting portion and a wire bonding pad portion And a step of plating the solder ball pad with a noble metal. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the metal plate of the semiconductor chip mounting portion and a conductor circuit around the metal plate are independent. 3. The surface of the metal plate serving as a semiconductor chip mounting portion is exposed by removing the surface copper foil and then grinding and removing the surface thermosetting resin composition and the glass cloth base material layer by sandblasting. The method for manufacturing a printed wiring board according to claim 1, wherein the printed wiring board is formed. 4. The printed wiring board according to claim 1, wherein the thermosetting resin is a polyfunctional cyanate ester and a thermosetting resin composition containing the cyanate ester prepolymer as an essential component. Production method.