JP2000150714A - Printed wiring board for semiconductor plastic package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve connection reliability between an inner layer metallic plate and an outer layer copper foil and heat dissipation property, by electrically connecting a projection formed in a metallic plate to a metallic foil in a surface at a die pad side and electrically connecting it to a copper layer in a rear at a die pad side. SOLUTION: A through hole whereto metallic plating is applied and a tip of a metallic conic trapezoid projection part (e) are electrically connected by copper plating and a rear is electrically connected by copper plating also to a copper foil in a circumference which becomes a ball pad part. According to this constitution, heat generated from a semiconductor chip (h) is conducted from a semiconductor chip mounted part through the conic trapezoid projection part (e) of a metallic plate (d), transferred to the metallic plate (d), conducted to a solder ball pad through a metallic conic trapezoid projection (e) at the opposite side and diffused to a mother board printed wiring board jointed by a solder ball (k). Good connection reliability between the inner layer metallic board (d) and an outer layer copper foil and good heat dissipation property are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel metal-containing semiconductor plastic package having at least one semiconductor chip mounted on a small printed wiring board. More specifically, the present invention relates to a novel semiconductor plastic package containing a metal plate, which is excellent in connection reliability and heat dissipation between the inner metal plate and the outer copper foil, and which can greatly improve the popcorn phenomenon. The obtained printed wiring board is suitable for use in a multi-terminal high-density semiconductor plastic package used at a relatively high wattage, 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, for example, a plastic ball grid array (P-BG
A) or a plastic land grid array (P-LGA), etc., a semiconductor chip is fixed on the upper surface of a plastic printed wiring board, and this chip is connected to a conductor circuit formed on the upper surface of the printed wiring board by wire bonding, and printed. Using solder balls on the lower surface of the wiring board, form conductor pads for connection to the motherboard printed wiring board,
A semiconductor plastic package having a structure in which front and back circuit conductors are connected by plated through holes and a semiconductor chip is sealed with a resin is known. In the known structure, a plated heat diffusion through hole is formed from the upper metal foil to the lower surface for fixing the semiconductor chip, in order to diffuse the heat generated from the semiconductor to the motherboard printed wiring board. . Through the through hole,
Moisture is absorbed by the resin adhesive containing silver powder used for fixing the semiconductor, and there is a risk of causing interlayer blisters due to heating during mounting on the motherboard and heating when removing the semiconductor components from the motherboard. Is called the popcorn phenomenon. When this popcorn phenomenon occurs, the package often becomes unusable,
This phenomenon needs to be greatly improved. In addition, higher functionality and higher density of semiconductors mean more and more heat generation, and heat dissipation is insufficient with only through holes directly below the semiconductor chip for heat dissipation.

[0003]

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

[0004]

That is, 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 surface of the printed wiring board is provided on at least one surface thereof. One semiconductor chip is fixed with a heat conductive adhesive, the metal plate and the circuit on the surface are insulated with a thermosetting resin composition, and the circuit conductor formed on the surface of the printed wiring board and the semiconductor chip are Are connected by wire bonding, at least, a signal transmission 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 a metal plate and a through-hole conductor insulated with a resin composition are connected and at least a semiconductor chip, a wire, and a bonding pad are resin-sealed, and a part of the printed wiring board is provided. The projections formed on the metal plate constituting the metal foil directly fix the semiconductor chip on the die pad side, the solder layer for heat dissipation on the back side, the copper layer formed on the surface on the ball pad side, and the solder for heat dissipation on the back side A printed wiring board for a semiconductor plastic package having a structure electrically connected to the copper layer formed on the surface of the ball pad is formed, and a semiconductor chip is bonded and fixed to the surface with a thermally conductive adhesive. And a semiconductor plastic package having a structure in which solder balls are connected to the back surface. The resulting package has good heat dissipation due to good adhesion between the metal plate and the surface gold foil, excellent adhesion of the solder balls to the substrate, no moisture absorption from the lower surface of the semiconductor chip, and moisture absorption. Subsequent heat resistance, ie the popcorn phenomenon, is greatly improved.
Furthermore, by using a polyfunctional cyanate ester composition as the thermosetting resin, a package having excellent electrical insulation properties and migration resistance after pressure cooker is provided. In addition, the semiconductor plastic package of the present invention is suitable for mass production, and has improved economy.

[0005]

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. At least the front end of the metal projection formed on both sides of the metal projection is exposed,
The rear surface is provided with a metal projection so that the metal projection is exposed on the front surface, avoiding the pad portion for connecting the solder ball. After the metal protrusion is desmeared, a through-hole is opened by a drill or a laser so as not to come into contact with the metal plate, the whole is metal-plated, a circuit is formed, and a semiconductor chip mounting portion, a wire bonding pad portion, and a ball pad are formed. The part is covered with a plating resist, and nickel plating and gold plating are performed. On the metal foil portion for mounting the semiconductor chip on the truncated cone of the surface, the semiconductor chip is fixed with a heat conductive adhesive, the semiconductor chip is connected to the surrounding circuit conductor by wire bonding, at least the semiconductor chip, the bonding wire and The bonding pad is sealed with resin, and the solder ball pad connected to the copper plated copper layer on the metal-plated and precious metal-plated frustoconical projection on the back side is melted and joined to the motherboard printed wiring board The circuit conductors on the front and back and the plated through holes for conduction have a structure insulated from the metal plate by the thermosetting resin composition.

In a known method of fixing a semiconductor chip on the upper surface of a metal plate 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 had to be dissipated and the popcorn phenomenon could not be improved. In the present invention, first, a clearance hole or a slit hole is formed on both surfaces of a metal flat plate as a metal plate by a known etching method or the like, leaving a frustoconical metal projection. Next, a thermosetting resin layer is formed slightly lower than the height of the metal projections on both surfaces, and a metal foil slightly thicker than the metal projection exposure height is arranged on both surfaces, and heated and pressed, preferably under vacuum, Lamination molding is performed to create a double-sided metal foil-clad laminate containing an inner metal plate. The method of forming the metal plate is not particularly limited. For example, first, an etching resist is attached to a metal flat plate in an area where a metal protrusion is to be formed.
30-70% The metal plate is etched away. Next, leave the etching resist in a circular shape at the location where the metal projection is to be formed, and at the same time remove the etching resist at the location where the clearance hole or slit hole is to be formed. At the same time, a metal plate is formed by a method of forming a clearance hole or a slit hole.

The surface of the metal plate on which the truncated conical protrusions and the clearance holes or slit holes are formed is subjected to 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 as needed. The surface treatment is performed so that a plurality of truncated cone-shaped protrusions are formed on both surfaces, and the truncated cone-shaped metal protrusions are slightly exposed above and below a metal plate on which clearance holes or slit holes are formed. An insulating portion is entirely formed from the curable resin composition.
The formation of the insulating portion using the thermosetting resin composition is performed using a prepreg sheet, a resin sheet, a resin-coated metal foil, or a coated resin layer that is impregnated with a semi-cured thermosetting resin composition and dried. . The height of the insulating part is such that the clearance hole or slit hole is filled with thermosetting resin at the time of lamination molding, and at the same time, the truncated cone-shaped metal projections are joined to the metal foil of the front and back layers on the metal foil parts on the front and back sides. To make a double-sided metal foil-clad laminate.

[0008] In the obtained double-sided metal foil-clad laminate, the portion where the tip of the double-sided truncated conical projection is in contact with the surface layer metal foil is
The metal foil is removed by a known method such as etching. However, on the semiconductor chip side surface, the tip of the truncated conical projection is exposed to the surface independently of the metal foil or is entirely removed. On the back side where the ball pad is formed, the metal protrusions are exposed avoiding the place where the ball pad is formed, and the resin layer adhering to the surface layer is removed by desmear treatment or the like, and the through hole is mechanically drilled or laser-cut The whole is metal-plated by a known method. The metal-plated through hole and the tip of the metal truncated conical projection are electrically connected by copper plating, and the back surface is also electrically connected to the surrounding copper foil to be a ball pad by copper plating. After forming a circuit on the front and back sides by a known method, at least the surface portion of the semiconductor chip mounting portion, the bonding pad portion, and the solder ball pad portion on the back surface are covered with a plating resist, and nickel or gold plating is performed. Thereafter, the semiconductor chip is bonded and fixed to the semiconductor chip mounting portion on the surface with a heat conductive adhesive, and wire bonding is performed, and at least the semiconductor chip, the wires, and the bonding pads are resin-sealed. 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 frustoconical projection of the metal plate, is transmitted to the metal plate, and is transmitted to the solder ball pad through the frustoconical projection on the opposite surface. , Spread on the motherboard printed wiring board joined by solder balls.

The side surface of the metal plate may be in a form coated with the thermosetting resin composition, in an exposed form, or in any form. 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. If necessary, a desmear treatment is performed, and then a metal layer is formed inside the through-hole by electroless plating or electrolytic plating to form a plated through-hole.

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

On the printed circuit board, on the frustum of a metal plate having a frustum-shaped projection serving as an inner layer, it is joined to a metal foil of the surface layer as it is or by attaching conductive solder or the like and joined. A semiconductor chip is fixed on a surface metal foil using a heat conductive adhesive, and the semiconductor chip and a bonding pad of a printed wiring board circuit are connected by a wire bonding method. The pad is sealed with a known sealing resin.

[0013] A solder ball is connected to the solder ball connecting conductor pad on the opposite side of the semiconductor chip to form a P-BGA, and the solder ball is superimposed on a circuit on a motherboard printed wiring board. When making a P-LGA without attaching solder balls to the package and mounting it on the motherboard printed wiring board, the solder ball connection conductor pad formed on the motherboard printed wiring board surface and the solder ball conductor for the P-LGA The pad and
The solder balls are connected by heating and melting.

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

The height of the metal frustoconical projection of the present invention is not particularly limited, but is preferably 50 to 150 μm. Also, the thickness of the insulating layer such as prepreg, resin sheet, metal foil with resin, coating resin, etc. is slightly lower than the height of the metal truncated cone-shaped projection,
Preferably, it is lower by 5 to 15 μm, and after lamination molding, it is connected to at least a part of the surface metal foil. The size of the truncated cone is not particularly limited, but generally, the diameter of the bottom is 0.5 to 5 m
m, the upper diameter is 0-1 mm.

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. The opposite is true.

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 an unsaturated group-containing polyphenylene ether resin. 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, JP-B-41-1928 and JP-B-43-1846
8, polyfunctional cyanate compounds described in JP-A-44-4791, JP-A-45-11712, JP-A-46-41112, JP-A-47-26853 and JP-A-51-63149 can also be used. Further, a prepolymer having a molecular weight of 400 to 6,000 and having a triazine ring formed by trimerization of a cyanato group of these polyfunctional cyanate compounds is used. This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate ester monomer with a catalyst such as an acid such as a mineral acid or a Lewis acid; a base such as a tertiary amine such as sodium alcoholate; or a salt such as sodium carbonate. It can be obtained by: The prepolymer also contains some unreacted monomers and is in the form of a mixture of the monomer and the prepolymer, and such a raw material is suitably used for the purpose of the present invention. Generally, it is used after being dissolved in a soluble organic solvent.

As the epoxy resin, a generally known epoxy resin can be used. Specifically, liquid or solid bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin; butadiene, pentadiene, vinylcyclohexene, dicyclopentyl ether, etc. And polyglycidyl compounds obtained by reacting a polyol, a hydroxyl-containing silicone resin with an epohalohydrin, and the like. These may be used alone or in combination of two or more.

As the polyimide resin, generally known ones can be used. Specific examples 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, natural rubber; polyethylene, polypropylene, polybutene, poly-4-methyl Penten, polystyrene, A
S resin, ABS resin, MBS resin, styrene-isoprene rubber, polyethylene-propylene copolymer, 4-fluoroethylene-6-fluoroethylene copolymers; polycarbonate, polyphenylene ether, polysulfone, polyester, polyphenylene sulfide, etc. High molecular weight prepolymers or oligomers; polyurethanes and the like are exemplified, and are appropriately used. 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. 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 fabrics are used. Specific examples include known glass fiber cloths such as E glass, S glass, and D glass, wholly aromatic polyamide fiber cloths, and liquid crystal polyester fiber cloths. These may be mixed. Alternatively, a thermosetting resin composition applied to the front and back of a film such as a polyimide film and heated to a semi-cured state can be used.

As the outermost metal foil, generally known ones can be used. Preferably, a copper foil, a nickel foil or the like having a thickness of 3 to 18 μm is used.

The 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 slit hole wall is separated by a thermosetting resin composition and is insulated. 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. Further, a resin sheet in a semi-cured state without using a base material and a metal foil with a resin can also be used. Alternatively, paints can be used. The temperature for forming a resin layer such as a prepreg is generally 100 to 180 ° C. The time is 5 to 60 minutes, and is appropriately selected depending on the desired flow rate.

The method for producing the semiconductor plastic package containing the metal plate of the present invention is not particularly limited. For example, the following method (see FIG. 1) is used. (1) Cover the entire surface of the metal plate with a liquid etching resist,
After heating to remove the solvent, the semiconductor chip is fixed, leaving the entire resist in the range of forming the metal truncated conical projection on the opposite surface, dissolving the metal plate to a predetermined thickness by etching, and then removing the etching resist. After attaching the etching resist to the places where the frustoconical projections are formed again on both sides,
The etching resist is removed from the portion that becomes the clearance hole while remaining in a circular shape, and etching is performed from above and below with an etching solution having the same pressure, so that a truncated cone-shaped projection is formed on the front and back surfaces, and at the same time a clearance hole is formed. Chemical treatment such as copper oxide treatment is applied to the metal plate surface, prepreg, resin sheet, copper foil with resin, or coated resin layer is placed on the front and back, and if necessary, copper foil is placed, (2) heating and pressing ,
Laminate under vacuum, (3) drill through holes, etc. (4) Leave the copper foil on the truncated cone of the metal plate, the entire surface on the front side, the copper foil on the back side where the solder ball is formed, After removing the copper foil on the truncated cone by etching and desmearing, (5) copper plating the whole, (6) after forming the circuit on the front and back, semiconductor mounting part, bonding pad part and solder A resist is formed on the part other than the ball pad part, nickel plating and gold plating are applied. (7) The semiconductor chip is bonded and fixed on the surface with silver paste, and after wire bonding, at least the semiconductor chip, wires and wire bonding pads are sealed with resin. I do. On the back surface, a solder ball is melt-bonded to a pad to form a semiconductor plastic package.

[0030]

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, and uniformly stirred and mixed to obtain Varnish A. Apply this varnish to thickness 100
μm glass woven fabric, dried and gelled (at 170
C) 50 seconds, 170 ° C., 20 kgf / cm ² , and a 137 μm-thick semi-cured prepreg B having an insulating layer thickness of 137 μm was prepared so that the resin flow was 10 mm in 5 minutes. On the other hand, the thickness of the inner metal plate
Prepare an alloy plate of 0 μm Cu: 99.9%, Fe: 0.07%, P: 0.03%,
Leave the etching resist on the semiconductor chip mounting part of the 50 mm square package and the area on the opposite side from both sides.
The metal plate was etched by 130 μm so that the front and back surfaces of the central portion were convex.
A liquid etching resist is attached to the entire surface by 25 μm,
A 200 μm-diameter circular etching resist is left in the center of the semiconductor chip mounting part and the part that will become the truncated conical projection formed on the back surface, the etching resist in the clearance hole part is removed, and the metal plate is melted by etching from above and below 130mm height, bottom diameter within 13mm square at the center of the front and back of the metal plate
658 μm, 144 cone-shaped protrusions with an upper diameter of 162 μm in the table,
At the same time as making 64 holes on the back surface, a clearance hole (FIG. 1, c) having a hole diameter of 0.6 mm was made. A black copper oxide treatment is applied to the entire surface of the metal plate, the prepreg B (FIG. 1, b) is placed on the front and back surfaces, and a 12 μm electrolytic copper foil (FIG. 1,
a) was placed and laminated and molded at 200 ° C., 20 kgf / cm ² , and a vacuum of 30 mmHg or less for 2 hours to be integrated. An etching resist is attached to the front and back, the front surface is the entire surface of the semiconductor chip mounting part with protrusions, and the back surface is only the part on the truncated cone-shaped protrusion, diameter 20
After removal by etching at 0 μm, after desmearing, a through hole (f in FIG. 1) having a diameter of 0.25 mm was drilled, and copper plating was applied by electroless plating and electrolytic plating at 20 μm. The etching resist is attached to the front and back, and the circuit such as the semiconductor chip mounting part at the center of the front surface, the solder ball joint part plated with copper on the copper foil on the back side and the copper plating on the truncated conical protrusion connected to this After forming the circuit and dissolving and removing the resist, a plating resist is formed except for the semiconductor chip mounting portion, the wire bonding portion, and the ball pad portion on the back surface, and nickel,
The printed wiring board was completed by applying gold plating. A 13 mm square semiconductor chip (see FIG. 1) is formed on the electrically conductive copper surface by contacting the truncated conical protrusion (FIG. 1, e) which is the semiconductor chip mounting portion on the surface with the plated copper (FIG. 1, j). 1, h) is bonded and fixed with a silver paste, wire bonding is performed, and then a semiconductor chip, wires and bonding pads are resin-sealed using an epoxy sealing compound containing silica, and solder balls are bonded to the back surface. A semiconductor package was created. Solder balls (FIG. 1, k) of this semiconductor plastic package were melt-bonded to an epoxy resin mother board printed wiring board. Table 1 shows the evaluation results.

Example 2 700 parts of epoxy resin (trade name: Epikote 5045, manufactured by Yuka Shell Epoxy Co., Ltd.) and epoxy resin (trade name: E
300 parts of SCN220F, manufactured by Sumitomo Chemical Co., Ltd.), 35 parts of dicyandiamide, and 1 part of 2-ethyl-4-methylimidazole are uniformly dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide, and this is woven into a glass cloth having a thickness of 100 μm. Impregnated,
Allow to dry, gel time (at 170 ° C) for 10 seconds, resin flow 98
A no-flow prepreg (prepreg C) having a thickness of μm and a high-flow prepreg (prepreg D) having a gelation time of 150 seconds and a resin flow of 18 mm were prepared. Lamination conditions: 190 ° C, 30kgf
Laminate molding was carried out for 2 hours by operating in the same manner as in Example 1 except that the pressure was changed to / cm ² and 30 mmHg. A printed wiring board for a semiconductor plastic package was prepared by performing the same operation as in Example 1 except that the entire surface of the rear projection region was removed by etching. Table 1 shows the evaluation results.

COMPARATIVE EXAMPLE 1 Two prepregs B (FIG. 2, b) of Example 1 were used, and 12 μm electrolytic copper foil (FIG. 2, a) was arranged on the upper and lower sides at 200 ° C. and 20 ° C.
Laminate molding was performed for 2 hours under a vacuum of kgf / cm ² and 30 mmHg or less to obtain a double-sided copper-clad laminate. A through hole (FIG. 2, g) having a hole diameter of 0.25 mmφ was drilled at a predetermined position, and copper plating was performed after desmearing. 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 (FIG. 2, l) for heat dissipation formed at a place where the semiconductor chip is mounted, and a semiconductor chip (FIG. 2, n) is formed thereon with a silver paste (FIG. 2, n).
h) were bonded, and after wire bonding, resin sealing was performed in the same manner as in Example 1 using a compound for epoxy sealing (FIG. 2, m), and solder balls (FIG. 2, k) were joined. It was joined to the motherboard in the same manner as in Example 1. Table 1 shows the evaluation results.
Shown in

Comparative Example 2 Two prepregs D of Example 2 were used at 190 ° C. and 20 kgf / 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 by operating in the same manner as in Comparative Example 1, and the semiconductor chip mounting portion was cut out with a counterbore machine, and a 200 μm-thick copper plate (FIG. 3,
d) was bonded in the same 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. A semiconductor chip (FIG. 3, h) was bonded directly to the heat sink with a silver paste (FIG. 3, n), connected by wire bonding, and sealed with a liquid epoxy resin (FIG. 3, m). Then, the same operation as in Example 1 was performed to join the printed circuit board to the motherboard. Table 1 shows the evaluation results.

[0034] Table 1 Item implementation example comparisons Example 1 2 1 2 ball shear strength 1.5 0.8 over over (kgf) heat resistance A after moisture absorption) normal status abnormality Not determined No change No change 24hrs. No problem No abnormality None 48hrs. No abnormalities No abnormalities No abnormalities 72hrs. No abnormalities No abnormalities No abnormalities 96hrs. No abnormalities No abnormalities Partial peeling 120hrs. No abnormalities Partial peeling partial peeling 144hrs. No abnormalities Partial peeling Partial peeling 168hrs. No abnormalities Partial peeling Partial peeling Heat resistance after moisture absorption B) Normal No abnormality-No abnormality No abnormality 24 hrs. No abnormality Partial peeling Partial peeling 48 hrs. No abnormality Large peeling Large peeling 72 hrs. No abnormality Wire break Wire break 96 hrs. No abnormalities Wire breaks Wire breaks 120hrs. No abnormalities Wire breaks Wire breaks 144hrs. No abnormalities − − 168hrs. No abnormalities − −

[0035] Table 1 (Continued) Item implementation example comparisons Example 1 2 1 2 pressure cooker treatment after the insulation resistance (Omega) normal state 4X10 ¹⁴ over ^{6X10 14 6X10 14 200hrs. 7X10 12} 5X10 12 5X10 8 500hrs. ^{5X10 11 3X10 11 <10 8 700hrs} . 6X10 10 4X10 10 over 1000hrs. 4X10 ¹⁰ 2X10 ¹⁰ over migration resistance (Omega) normal state 6 × 10 ¹³ over ^{5X10 13 4X10 13 200hrs. 5X10 11} 4X10 11 3X10 9 500hrs. 4X10 11 4X10 11 ^{<10 8 700hrs. 1X10 11 1X10} 11 over 1000hrs. 9X10 ¹⁰ 8X10 ¹⁰ over the glass transition temperature (℃) 234 160 234 160 heat radiation (℃) 33 34 56 48

<Measurement Method> 1) Ball Shear Strength A solder ball was attached to a ball pad having a diameter of 0.6 mm, and the strength at the time of peeling by pressing from the side was measured. 2) Heat resistance after moisture absorption A) JEDEC STANDARD TEST METHOD A113-A LEVEL3: 30 ℃ ・ 60%
After the treatment with RH for a predetermined time, the presence or absence of an abnormality in the substrate after three cycles of reflow soldering at 220 ° C. was confirmed by cross-sectional observation and electrical check. 3) Heat resistance after moisture absorption B) JEDEC STANDARD TEST METHOD A113-A LEVEL2: 85 ℃ ・ 60%
After processing at RH for a predetermined time (Max. 168 hrs.), The presence or absence of abnormality in the substrate after three cycles of reflow soldering at 220 ° C. was confirmed by cross-sectional observation and electrical check. 4) Insulation resistance value after pressure cooker process A comb-shaped pattern between terminals (line / space = 70/70 μm) was created, and the prepregs used were placed on each of these patterns. After treatment for a predetermined time at atmospheric pressure, post-treatment was performed at 25 ° C. and 60% RH for 2 hours, and insulation resistance between terminals was measured 60 seconds after 500 VDC was applied. 5) Migration resistance The test piece of the above 4) was applied at 85 ° C. and 85% RH at 50 VDC, and the insulation resistance between the terminals was measured. 6) Glass transition temperature Measured by the DMA method. 7) Heat dissipation The package was bonded to the same motherboard printed wiring board with solder balls and used continuously for 1000 hours before measuring the package temperature.

[0037]

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 surface circuit 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 the semiconductor chip are connected by wire bonding, and 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 conductor pad for connection with the solder ball. Are connected by a through-hole conductor insulated with a metal plate and a resin composition, and at least a semiconductor chip, a wire,
A printed wiring board used in a semiconductor plastic package having a structure in which a bonding pad is resin-sealed, wherein a front surface copper layer of the printed wiring board and a copper layer formed on a surface of a back surface of a solder ball pad for heat dissipation on the back surface are formed. By providing a printed wiring board for a semiconductor plastic package having a structure of being electrically connected, furthermore, of the copper layer formed on the surface of the solder ball pad side, the protrusion and the copper layer are electrically connected. Provided is a printed wiring board for a semiconductor plastic package having the above structure. A semiconductor chip bonded and fixed to the semiconductor chip mounting portion with a heat conductive adhesive,
A semiconductor plastic package in which wires and bonding pads are resin-sealed is joined to a motherboard printed wiring board by melting solder balls adhered to gold-plated pads on the back surface of the package. With the above structure, heat generated from the semiconductor chip is transmitted from the upper metal truncated conical projection to the metal plate through the heat conductive adhesive, and is joined to the ball pad portion on the rear surface through the lower frustoconical projection. Escapes to the solder balls and spreads on the motherboard printed wiring board. According to the present invention, the connection reliability between the inner layer metal plate and the outer layer copper foil, excellent heat dissipation, excellent adhesive strength with solder balls, no moisture absorption from the lower surface of the semiconductor chip, and heat resistance after moisture absorption The present invention provides a printed wiring board for a semiconductor plastic package in which the properties, that is, the popcorn phenomenon, are greatly improved. Further, by using a polyfunctional cyanate ester resin composition as a resin,
A printed wiring board for a semiconductor plastic package having excellent insulation properties and migration resistance after a pressure cooker treatment is provided. In addition, it is suitable for mass production,
A novel structure of a printed wiring board for a semiconductor plastic package having improved economy is provided.

[Brief description of the drawings]

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

FIG. 2 is a manufacturing process diagram of a semiconductor plastic package of Comparative Example 1.

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

[Explanation of symbols]

 a copper foil b prepreg B c clearance hole d metal plate e frustoconical projection f hole for through hole g through hole for front and back circuit conduction h semiconductor chip i copper foil j plated copper layer k solder ball l through hole for heat dissipation m sealing Stopping resin n Silver paste 0 Bonding wire p Plating resist q Prepreg C

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) H01L 23/14 R (72) Inventor Toshihiko Kobayashi 6-1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas Chemical Co., Ltd. Tokyo F-term in the factory (reference) 4F071 AA42 AA51 AA58 AA60 AB06B AF39 AF44B AF45 AH13 CA01 CD01 CD07 5E315 AA05 BB01 BB04 BB14 CC16 DD25 DD29 GG01

Claims (4)

[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 circuit on the front and back sides are insulated with a thermosetting resin composition, and the circuit conductor formed on the surface of the printed wiring board and the semiconductor chip are connected by wire bonding. A signal propagation circuit conductor on the printed wiring board of the present invention, and a circuit conductor formed on the opposite surface of the printed wiring board or a circuit conductor pad formed for connection to the outside of the package with a solder ball are formed by a metal plate and a resin. A printed circuit board for a semiconductor plastic package that is connected with a through-hole conductor insulated with the composition and at least seals the semiconductor chip, wires, and bonding pads with resin. In the wire plate, a projection formed on a metal plate constituting a part of the printed wiring board has a copper layer formed on a semiconductor chip side surface and a copper layer formed on a heat dissipation solder ball pad side surface on a back surface. Printed wiring board for semiconductor plastic package electrically connected to. 2. A solder ball in which, in the printed wiring board, an electrical connection between a protruding portion and the copper layer of a copper layer formed on a surface of the solder ball pad is formed on a part of the copper layer. 2. The printed wiring board for a semiconductor plastic package according to claim 1, wherein the printed wiring board is connected so as to avoid a place for fixing. 3. The method according to claim 1, wherein the metal plate is a copper alloy containing 95% by weight or more of copper.
The printed wiring board according to claim 1, wherein the printed wiring board is pure copper. 4. The printed wiring board according to claim 1, wherein the thermosetting resin is a thermosetting resin composition containing a polyfunctional cyanate ester and the cyanate ester prepolymer as essential components. .