JPH11330304A - Semiconductor plastic package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a semiconductor plastic package to be improved in heat dissipating properties and restrained from absorbing moisture through the underside of a chip, by a method wherein a semiconductor chip is fixed with thermally conductive adhesive agent to a metal foil which serves as a semiconductor chip mount where projections are brought into contact, and metal conical truncated projections are brought into contact with a metal foil on the opposite side. SOLUTION: A semiconductor plastic package has a structure where a metal plate (a) which is excellent in heat dissipating properties and provided with truncated conical projections (c) formed on its front and rear is arranged at the center in the thickness direction of a printed wiring board, the metal projections (c) are brought into direct contact with a front and a rear metal foil or bonded to them through the intermediary of thermally conductive adhesive agent, a semiconductor chip is fixed to the metal foil where the metal projections (c) are brought into contact, the semiconductor chip is connected to peripheral circuit conductors with bonding wires, and the semiconductor chip is sealed up with resin together with the bonding wires and bonding pads. A front and a rear circuit conductor and through-holes plated for continuity are insulated with thermosetting resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel semiconductor plastic package in which at least one semiconductor chip is mounted on a small printed wiring board. In particular, it is suitable for relatively high wattage, multi-terminal, high-density semiconductor plastic packages such as microprocessors, microcontrollers, ASICs, and graphics. This 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, a semiconductor chip is fixed on the upper surface of a plastic printed wiring board such as a plastic ball grid array (P-BGA) or a plastic land grid array (P-LGA) as a semiconductor plastic package.
This chip is bonded to the conductor circuit formed on the upper surface of the printed wiring board by wire bonding, and the lower surface of the printed wiring board is formed with conductor pads for connection to the motherboard printed wiring board using solder balls. 2. Description of the Related Art A semiconductor plastic package having a structure in which conductors are connected by plated through holes and a semiconductor chip is sealed with a resin is known. In the known structure, it is also known that a plated heat diffusion through hole connecting from the upper metal foil to the lower surface for fixing the semiconductor chip is formed in order to diffuse heat generated from the semiconductor to the motherboard printed wiring board. ing.

Through the through holes, moisture is absorbed by the resin adhesive containing silver powder used for fixing the semiconductor, and is heated by mounting at the time of mounting on the motherboard and by heating at the time of removing the semiconductor parts from the motherboard. This is 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.

[0004]

SUMMARY OF THE INVENTION The present invention provides a semiconductor plastic package which solves the above problems.

[0005]

According to the present invention, a metal plate having substantially the same size as a printed wiring board is disposed substantially at the center in the thickness direction of the printed wiring board, and at least one metal plate is provided on one surface of the printed wiring board. Is fixed with a heat conductive adhesive, the metal plate and the signal transmission circuit conductor on the surface are insulated with a polyfunctional cyanate ester resin composition or the like, and the signal transmission circuit conductor on the surface of the printed wiring board is A semiconductor chip was connected by wire bonding, and at least the circuit conductor was insulated with a metal plate and a resin composition by a circuit conductor formed on the opposite surface of the printed wiring board or a conductor pad for connection with the solder ball. In a semiconductor plastic package having a structure in which at least a semiconductor chip, a wire, and a bonding pad are sealed with a resin, the printed wiring is connected by a through-hole conductor. A plurality of truncated cone-shaped metal protrusions are formed on a metal plate constituting a part of the metal plate so as to directly contact with a metal foil for directly fixing a semiconductor chip or to be joined via a heat conductive adhesive; The semiconductor chip is fixed with a thermally conductive adhesive on the metal foil that will be the semiconductor chip mounting part on the surface with which it is in contact, and a plurality of metal truncated conical protrusions are also formed on the back of the metal foil on the opposite side of the semiconductor chip fixing surface The present invention provides a semiconductor plastic package having a structure that is formed to be in direct contact with or bonded to a semiconductor plastic package. In the semiconductor plastic package of the present invention, the heat generated from the semiconductor chip is conducted to the metal plate from the truncated conical metal protrusion through the heat conductive adhesive and from the metal truncated conical protrusion on the opposite surface to the motherboard printed wiring board through the solder ball. It has an escape structure. ADVANTAGE OF THE INVENTION According to this invention, it is excellent in heat dissipation, there is no moisture absorption from the lower surface of a semiconductor chip, heat resistance after moisture absorption, that is, a popcorn phenomenon is largely improved, electrical insulation after pressure cooker, and migration resistance. The present invention provides a semiconductor plastic package having a novel structure, which is excellent in the above-mentioned characteristics, is suitable for mass productivity, and has improved economic efficiency.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A semiconductor plastic package according to the present invention is provided with a metal plate having good heat dissipation and a truncated conical projection formed on the front and back sides at substantially the center in the thickness direction of the printed wiring board. The semiconductor chip is directly contacted with the front and back metal foils or bonded via a heat conductive adhesive, and the semiconductor chip is fixed with the heat conductive adhesive on the metal foil to which the truncated conical protrusion on the surface contacts. Is connected to the surrounding circuit conductors by wire bonding, and at least a semiconductor chip,
Bonding wires and bonding pads are sealed with resin, solder balls are bonded to the metal foil connected in the same way as the truncated conical protrusions on the back surface, and the solder balls are bonded to the motherboard printed wiring board, The front and back circuit conductors and the plated through holes for conduction have a structure insulated by the thermosetting resin composition. .

In a known method of fixing a semiconductor chip on the upper surface of a metal-core printed wiring board having a through hole, heat from the semiconductor chip is transferred to a heat-dissipating through hole immediately below, similarly to a conventional P-BGA package. It has to drop heat to dissipate heat, and the popcorn phenomenon cannot be improved. According to the present invention, first, a plurality of truncated cone-shaped protrusions are formed at positions where a semiconductor chip is fixed by a known method such as etching a metal plate serving as a metal core. Also, a clearance hole or a slit hole larger than the diameter of the through hole is formed at a position where the through hole is to be formed by a known etching method, a punching method, , Formed on the metal core by laser or the like.

The surface of the metal plate on which the truncated conical protrusions and the clearance holes or slit holes are formed is a surface for improving adhesion and electrical insulation such as oxidation treatment, formation of fine irregularities, and film formation by a known method. Perform processing as needed. The surface treatment, a plurality of truncated cone-shaped protrusions are formed on both surfaces, and the truncated cone-shaped metal protrusions or protrusions having a thermally conductive adhesive adhered to a metal plate on which clearance holes or slit holes are formed. Is formed, and the entire surface is formed of a thermosetting resin composition. The formation of the insulating portion using the thermosetting resin composition is performed using a prepreg, a resin sheet, a resin-coated metal foil, or a coated resin layer in which a semi-cured thermosetting resin composition is impregnated with a base material and dried. The height of the insulating portion is set such that, after lamination molding, the truncated cone-shaped metal projection or the projection to which the heat conductive adhesive is attached is in contact with the metal foil portion for fixing the semiconductor chip on the surface, and the heat generated from the semiconductor chip is Is conducted from this mounting part, passes through the truncated cone-shaped protrusion of the inner layer metal plate, transmits to the metal plate, conducts to the solder ball pad through the metal truncated cone-shaped protrusion on the opposite surface, and joins with the solder ball Spread on the printed circuit board. On the front and back, a prepreg, a resin sheet, a resin-coated metal foil, a coating resin layer, and the like having a resin amount and a resin flow capable of sufficiently filling the clearance hole or the slit hole are arranged. If necessary, a metal foil, a single-sided metal foil-clad laminate, a single-sided circuit-formed double-sided metal foil-clad laminate, or a single-sided circuit-formed multilayer board is placed, and laminated and integrated under heat and pressure, preferably under vacuum.

Regarding the side surface of the metal plate, any of a shape embedded in the thermosetting resin composition and an exposed shape may be used. Is preferred. In addition, in order to form a through-hole printed wiring board by the subtractive method, a metal foil slightly larger than the printed wiring board is arranged on the outermost layer on the front and back sides during lamination molding, and heating,
By laminating and molding under pressure, a metal foil-clad laminate with a metal plate covered on both sides with a metal foil for forming an outer layer circuit is formed.

In the case of laminating and molding without using a metal foil for the front and back layers, a circuit is formed by a known additive method to produce a printed wiring board.

In a plate made by the above-described subtractive method or semi-additive method, a through-hole for conducting a circuit on the front and back is formed in a portion other than a portion where a semiconductor is fixed by a drill or the like by a known method. Drill holes.

The through hole for conducting the front and back 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. Apply desmear treatment as necessary, then form a metal layer inside the through hole by electroless plating or electrolytic plating, and form a plated through hole,
In the full-additive method, wire bonding terminals, circuits, solder ball pads, and the like are simultaneously formed on the front and back surfaces.

In the semi-additive method, both the front and back surfaces are plated at the same time as plating the through holes, and thereafter, circuits are formed on the upper and lower sides by a known method.

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

The semiconductor chip is fixed on the metal foil of the printed wiring board on which the semiconductor chip is mounted by using a heat conductive adhesive, and the semiconductor chip and the bonding pads of the printed wiring board circuit are wire-bonded. Then, 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 a solder ball to a solder ball connecting conductor pad on the opposite side of the semiconductor chip, and the solder ball is superimposed on a circuit on a motherboard printed wiring board. Connect to the printed wiring board. Alternatively, when making a P-LGA without attaching solder balls to the package and mounting it on the motherboard printed wiring board, the solder ball connection conductor pads formed on the motherboard printed wiring board surface and the P-LGA
The mother board and the printed wiring board are connected by heating and melting the solder ball conductor pads for the LGA and the solder balls.

Although the metal plate used in the present invention is not particularly limited, a metal plate having a high elastic modulus, a high thermal conductivity and a thickness of 30 to 500 μm is preferable. Specifically, pure copper, oxygen-free copper, and others,
An alloy of 95% by weight or more of copper with Fe, Sn, P, Cr, Zr, Zn, or the like is preferably used. Also, a metal plate or the like in which the surface of the alloy is plated with copper can be used.

The height of the metal truncated conical projection of the present invention is not particularly limited, but is preferably 50 to 150 μm. In addition, the thickness of the insulating layer of the prepreg, the resin sheet, the metal foil with resin, the coating resin, etc., is slightly lower than the height of the metal truncated cone-shaped projection, preferably 5 to 15 μm lower, and connected to the surface metal foil after lamination molding. . Alternatively, a thermally conductive adhesive is adhered onto the truncated cone, and is melt-connected to the outer metal foil during lamination molding to improve reliability. The size of the truncated cone is not particularly limited, but generally, the diameter of the bottom is 0.1 to 5 μm.
m, the diameter of the upper part is 0 to 1 μm. Known materials can be used as the heat conductive adhesive. Specifically, a generally known lead-free solder such as a silver paste, a copper paste, a solder paste, and a tin / silver / copper-based solder may be used.

The range of formation of the metal truncated conical protrusion is set to be equal to or less than the area of the semiconductor chip, generally within a range of 5 to 20 mm square, and to be present below the semiconductor chip fixing portion.

As the resin of the thermosetting resin composition used in the present invention, generally known thermosetting resins are used. Specific examples include an epoxy resin, a polyfunctional cyanate ester resin, a polyfunctional maleimide-cyanate ester resin, a polyfunctional maleimide resin, and a polyphenylene ether resin having an unsaturated group. These are used alone or in combination of two or more. Heat resistance, moisture resistance,
A polyfunctional cyanate resin composition is preferred in terms of 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-cyanatophenyl)
Phosphite, tris (4-cyanatophenyl) phosphate, and cyanates obtained by reacting novolak with cyanogen halide.

In addition to these, Japanese Patent Publication Nos. 41-1928 and 43-1846
8, polyfunctional cyanate compounds described in JP-A-44-4791, JP-A-45-11712, JP-A-46-41112, JP-A-47-26853 and JP-A-51-63149 can also be used. Further, a prepolymer having a molecular weight of 400 to 6,000 and having a triazine ring formed by trimerization of a cyanato group of the polyfunctional cyanate compound can also be used. This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate ester monomer using, for example, an acid such as a mineral acid or a Lewis acid; a base such as a sodium alcoholate or a tertiary amine; a salt such as sodium carbonate as a catalyst. 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 an 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 group-containing silicone resin with epihalohydrin, 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 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 can 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, and natural rubber; polyethylene, polypropylene, polybutene, poly-4- Methylpentene, polystyrene, AS resin, ABS resin, MBS resin, styrene-isoprene rubber, polyethylene-propylene copolymer, 4-fluoroethylene-6-fluoroethylene copolymers; polycarbonate, polyphenylene ether, polysulfone, polyester And high molecular weight prepolymers or oligomers such as polyphenylene sulfide; and polyurethane. In addition, other known inorganic or organic fillers, dyes, pigments, thickeners, lubricants, defoamers,
Various additives such as a dispersant, a leveling agent, a photosensitizer, a flame retardant, a brightener, a polymerization inhibitor, and a thixotropy-imparting agent are used in an appropriate combination as required. If necessary, the compound having a reactive group is appropriately blended with a curing agent and a catalyst.

The thermosetting resin composition of the present invention can be cured by heating itself, but has a low curing rate and is inferior in workability and economic efficiency. Can be used. The amount used is 0.005 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the thermosetting resin.

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

As the outermost metal foil, generally known ones can be used. Preferably, a copper foil, a nickel foil or the like having a thickness of 3 to 100 μm is used.

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 / 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 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. Also, a resin sheet in a semi-cured state without using a base material can be used. Alternatively, paints can be used. In this case, depending on the degree of the semi-cured state,
High flow, low flow, or no flow. In the case of no flow, when lamination molding is performed by heating and pressing, the flow of the resin is 100 μm or less, preferably 5 μm or less.
0 μm or less. At this time, it is important that the metal plate and the metal foil adhere to each other and no void is generated. The temperature at which the prepreg is made is generally between 100 and 180 ° C. The time is 5-60 minutes, depending on the degree of the desired flow
Select as appropriate.

The method of producing the semiconductor plastic package having the metal core of the present invention is not particularly limited. For example, the following method shown in FIGS. 1 and 2 is used. (1) After covering the entire surface of the metal plate a serving as the inner layer with the liquid etching resist b and removing the solvent by heating, the resist in a range where the semiconductor chip is fixed, the frustum of the metal cone on the opposite surface is formed, and (2) After the metal plate is melted to a predetermined thickness by etching, (3) the etching resist is left again as a small-diameter circular shape at the portions to be left as projections on the front and back surfaces. (4) Etching is performed from above and below with an etching solution having the same pressure to form a truncated cone-shaped projection c and a clearance hole d on the front and back surfaces, then remove the etching resist, and chemically treat the entire surface of the metal plate. (5) A prepreg (f in FIG. 2), a resin sheet,
A metal foil with resin or a coating resin layer is arranged, and a metal foil e is arranged as necessary. In this case, the insulating layer is formed such that the tips of the truncated cone-shaped protrusions remain slightly thinner than the thickness of the metal foil. (6) After laminating under heat, pressure, and vacuum, (7) A through hole g is drilled at a predetermined position with a drill or the like so as not to contact the inner metal plate, and the through hole is metal-plated. (8) Except for the mounting portion of the semiconductor chip k, the wire bonding pad, and the ball pad portion on the opposite surface, the semiconductor chip is covered with a plating resist 1 and plated with nickel and gold, and the semiconductor chip is bonded and fixed with a silver paste h. After wire bonding, resin sealing j is performed, and a solder ball m is bonded to the ball pad portion on the opposite surface to form 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 100 parts of bis (4-maleimidophenyl) methane were melted at 150 ° C. and reacted with stirring for 4 hours to obtain a prepolymer. This was dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. 400 parts of bisphenol A type epoxy resin (trade name: Epicoat 1001, Yuka Shell Epoxy Co., Ltd.) and cresol novolak type epoxy resin (trade name: ESCN-220F, Sumitomo Chemical Co., Ltd.) 60
0 parts were added and uniformly dissolved and mixed. Further, 0.4 part of zinc octylate is added as a catalyst, dissolved and mixed, and an inorganic filler (trade name: calcined talc BST-200, Nippon Talc Co., Ltd.) is added.
Varnish A was obtained by mixing uniformly with stirring.
This varnish is impregnated into a glass woven cloth having a thickness of 100 μm, dried, and gelled (at 170 ° C.) for 50 seconds, 170 ° C., 20 kgf / cm ² , 5 kg
A semi-cured prepreg B having an insulating layer thickness of 107 μm was prepared so that the resin flow per minute was 10 mm.

On the other hand, a 350 μm-thick Cu:
Prepare a 99.9%, Fe: 0.07%, P: 0.03% alloy plate, apply 25μm of liquid etching resist on the upper and lower sides, and dry it. On the front and back sides, a clearance hole of 50mm square package area Irradiation was carried out so that all the resist except for the resist remained, the resist in the clearance hole portion was dissolved and removed with a 1% sodium carbonate solution, and the upper and lower metal plates of about 65 μm were dissolved by etching from above and below. After dissolving and removing the etching resist, a liquid etching resist is adhered again, and a width of
At 2 mm intervals, cover the negative film created so that a circular resist with a diameter of 300 μm remains, irradiate with ultraviolet light, dissolve and remove the unexposed parts with 1% sodium carbonate solution, etch from both sides, and apply on both sides Height 114μm, bottom diameter 620μ
m and 25 truncated conical projections each having an upper diameter of 74 μm were formed, and a clearance hole having a hole diameter of 0.6 mmφ was formed. Apply black copper oxide treatment on the entire surface of the metal plate, place the above prepreg B on the front and back surfaces, place 12 μm electrolytic copper foil on the top and bottom, and laminate at 200 ° C, 20 kgf / cm ² , 30 mmHg or less vacuum for 2 hours Molded and integrated. Drill a 0.25mm diameter through hole in the center of the clearance hole so that it does not come into contact with the metal in the clearance hole, perform copper plating by electroless or electrolytic plating, and place 17μ in the hole.
m of the copper plating layer was formed. Attaching an etching resist on the front and back, overlaying a positive film, exposing and developing, forming a front and back circuit, forming a plating resist other than the semiconductor chip mounting part, bonding pad part and ball pad part, applying nickel and gold plating To complete the printed wiring board. A 13 mm square semiconductor chip is bonded and fixed with a silver paste on the surface where the truncated conical protrusion that is the semiconductor chip mounting part is in contact with the surface metal foil, wire bonding is performed, and then silica-filled epoxy sealing The semiconductor chip, wires, and bonding pads were resin-sealed using a compound for soldering, and solder balls were joined to form a semiconductor package. This semiconductor plastic package was bonded to an epoxy resin motherboard printed wiring board by melting solder balls. Table 1 shows the evaluation results.

Example 2 In Example 1, the height of the truncated conical projections on both sides was 109 μm.
m, silver paste was deposited on this trapezoid, 5 μm in height, prepreg B was placed on the top and bottom, and 12 μm electrolytic copper foil was placed on both outer sides, 200 ° C., 20 kgf / cm ² , and a vacuum of 30 mmHg or less. For 2 hours. Thereafter, a printed wiring board was prepared in the same manner, a semiconductor chip was bonded, wire-bonded, and resin-sealed to obtain a semiconductor plastic package. This was similarly joined to an epoxy resin motherboard printed wiring board. Table 1 shows the evaluation results.

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

COMPARATIVE EXAMPLE 2 700 parts of an epoxy resin (trade name: Epicoat 5045), 300 parts of an epoxy resin (trade name: ESCN220F), 35 parts of dicyandiamide, and 1 part of 2-ethyl-4-methylimidazole were prepared by mixing methyl ethyl ketone and dimethylformamide. Uniformly dissolved in a mixed solvent, impregnated in a glass woven cloth with a thickness of 100 μm and dried, gelling time (at 170 ° C) for 10 seconds, resin flow
High flow prepreg with 98μm no-flow prepreg (prepreg C), gel time 150 seconds, resin flow 18mm
(Prepreg D) was prepared. Two prepregs D were laminated and molded at 190 ° C., 20 kgf / cm ² and a vacuum of 30 mmHg or less for 2 hours 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 with a counterbore machine, and a thickness of 200 μm was formed on the back surface.
Using a punched-out Noflow prepreg C, a copper plate having a thickness of m was bonded in the same manner under heat and pressure to produce a printed wiring board with a heat sink. This slightly warped. A semiconductor chip was directly bonded to the heat sink with a silver paste, connected by wire bonding, and sealed with a liquid epoxy resin (FIG. 4). Similarly, it was joined to a motherboard printed wiring board. Table 1 shows the evaluation results.

Table 1 Item Example Comparison Example 1 2 1 2 Heat resistance after moisture absorption 1) Normal No abnormality No abnormality No abnormality No abnormality No abnormality 24hrs. No abnormality No abnormality No abnormality No abnormality 48hrs. No abnormality No abnormality No abnormalities No abnormalities 72hrs. No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities 96hrs. No abnormalities No abnormalities No abnormalities Partial peeling 120hrs. No abnormalities No abnormalities Partial peeling partial peeling 144hrs. No abnormalities No abnormalities Partial peeling Partial peeling 168hrs No abnormalities No abnormalities Partial peeling Partial peeling Heat resistance after moisture absorption 2) Normal No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities 24hrs. No abnormalities No abnormalities Partial peeling Partial peeling 48hrs. No abnormalities No abnormalities Large peeling Large peeling large 72hrs. No abnormalities No abnormalities Wire breaks Wires 96hrs. No abnormalities No abnormalities Wire breaks Wires 120hrs. No abnormalities No abnormalities Wire breaks Wires 144hrs. No abnormalities No abnormalities -. 168Hrs No problem No - - Glass transition temperature (℃) 234 234 234 160

[0039] Table 1 (Continued) Item implementation example comparisons Example 1 2 1 2 pressure cooker treatment after the insulation resistance (Omega) normal state ^{5 × 10 14 5 × 10 14} 6 × 10 14 5 × 10 14 200hrs 7 × 10 ¹² 6 × 10 ¹² 5 × 10 ¹² 5 × 10 ⁸ 500hrs. 6 × 10 ¹¹ 5 × 10 ¹¹ 3 × 10 ¹¹ <10 ⁸ 700hrs. 5 × 10 ¹⁰ 7 × 10 ¹⁰ 5 × 10 ¹⁰ −1000hrs ^{. 2 × 10 10 2 × 10} 10 1 × 10 10 -. migration resistance (Omega) normal state ^{6 × 10 13 5 × 10 13} 5 × 10 13 4 × 10 13 200hrs 5 × 10 11 6 × 10 11 4 × 10 ¹¹ 3 × 10 ⁹ 500 hrs. 4 × 10 ¹¹ 4 × 10 ¹¹ 4 × 10 ¹¹ <10 ⁸ 700 hrs. 1 × 10 ¹¹ 2 × 10 ¹¹ 1 × 10 ¹¹ −1000 hrs. 9 × 10 ¹⁰ 1 × 10 ¹¹ 8 × 10 ¹⁰ -Heat dissipation (° C) 36 35 56 48 Good Contact with surface metal foil Very good--

<Measurement method> 1) Heat resistance after moisture absorption ¹⁾ JEDEC STANDARD TEST METHOD A113-A LEVEL3: 30 ° C, 60
After the treatment at% RH for a predetermined time, 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. 2) Heat resistance after moisture absorption ²⁾ JEDEC STANDARD TEST METHOD A113-A LEVEL2: 85 ℃ ・ 60
After treatment 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. 3) Glass transition temperature Measured by the DMA method. 4) Insulation resistance after pressure cooker treatment A comb-shaped pattern was created between terminals (line / space = 70/70 μm), and the prepreg or resin layer used was formed on each of these patterns, and the resultant was cured by heating. After treatment at 121 ° C. and 2 atm for a predetermined time, post-treatment was performed at 25 ° C. and 60% RH for 2 hours, and after applying 500 VDC for 60 seconds, the insulation resistance value between the terminals was measured. 5) Migration resistance The test piece of the above 4) was applied at 85 ° C. and 85% RH at 50 VDC, and the insulation resistance between the terminals was measured. 6) Heat dissipation The package was adhered 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. 7) Contact with surface metal The cross section of the truncated cone was observed.

[0041]

According to the present invention, a metal plate having substantially the same size as a printed wiring board is disposed substantially at the center in the thickness direction of the printed wiring board, and at least one semiconductor chip is provided on one surface of the printed wiring board. Is fixed with a heat conductive adhesive, the metal plate and the circuit on the surface are insulated with a thermosetting resin composition such as a polyfunctional cyanate ester, and the circuit conductor formed on the surface of the printed wiring board and Connecting the semiconductor chip by wire bonding, at least a signal propagation circuit conductor on the printed wiring board on the surface, and a circuit conductor formed on the opposite surface of the printed wiring board or a connection conductor pad with the solder ball, A semiconductor plastic package having a structure in which at least a semiconductor chip, a wire, and a bonding pad are resin-sealed by connecting with a metal plate and a through-hole conductor insulated by a resin composition. A plurality of truncated-cone-shaped metal projections are formed on a metal plate constituting a part of the printed wiring board, on a metal foil back side for directly fixing a semiconductor chip. Contact with metal foil. Preferably, a heat conductive adhesive is deposited on the truncated cone,
At the time of lamination molding, the adhesive is melted to join the metal core and the surface metal foil. The semiconductor chip is fixed to this semiconductor mounting portion with a heat conductive adhesive, and the heat generated from the semiconductor chip passes through this metal plate frustoconical projection to the inner layer metal plate, and passes through the truncated conical projection on the back side of the metal plate. Provided is a semiconductor plastic package having a structure that escapes to a solder ball connected to a side metal foil and diffuses into a motherboard printed wiring board. According to the present invention, the semiconductor plastic package having the above-described configuration has excellent heat dissipation, does not absorb moisture from the lower surface of the semiconductor chip, and can significantly improve the heat resistance after moisture absorption, that is, the popcorn phenomenon, and can further improve mass productivity. The present invention provides a semiconductor plastic package having a novel structure, which is also suitable for an automobile and has improved economy.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a semiconductor plastic package according to a first embodiment.

FIG. 2 is a manufacturing process diagram of the semiconductor plastic package of the first embodiment.

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

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

[Explanation of symbols]

 a Metal plate b Etching resist c Metal frustoconical projection d Clearance hole e Metal foil f Pre-preg B g Through-hole for front and back circuit conduction h Silver paste i Bonding wire j Sealing resin k Semiconductor chip l Plating resist m Solder ball n Heat radiation through Hall o Prepreg C

Claims (3)

[Claims] 1. A metal plate having substantially the same size as a printed wiring board is disposed at a substantially central portion in a thickness direction of the printed wiring board, and at least one semiconductor chip is thermally conductively bonded to one surface of the printed wiring board. The metal plate and the signal transmission circuit conductor on the surface of the printed wiring board are insulated with a thermosetting resin composition, and the circuit conductor and the semiconductor chip are connected by wire bonding. The circuit conductor and the circuit conductor formed on the opposite surface of the printed wiring board or the circuit conductor pad formed for connecting the package to the outside with solder balls were insulated by a metal plate and a resin composition. In a semiconductor plastic package having a structure in which at least a semiconductor chip, a wire, and a bonding pad are resin-sealed by connecting through a through-hole conductor, A plurality of truncated cone-shaped metal projections are brought into contact with a metal foil directly fixing a semiconductor chip on a metal plate constituting a part of the plate, and the projections are brought into contact with the metal foil with a heat conductive adhesive as necessary, The semiconductor chip is fixed with a heat conductive adhesive on the semiconductor chip mounting metal foil on the surface where the projections are in contact, and a plurality of metal truncated cone-shaped projections are also formed on the back surface of the metal foil on the opposite side of the semiconductor chip fixing surface A semiconductor plastic package formed so as to be connected in the same manner as described above. 2. The method according to claim 1, wherein the metal plate is a copper alloy containing 95% by weight or more of copper.
2. The semiconductor plastic package according to claim 1, wherein the semiconductor plastic package is pure copper. 3. The semiconductor plastic package according to claim 1, wherein the insulating resin composition is a thermosetting resin composition containing a polyfunctional cyanate ester and the cyanate ester prepolymer as essential components.