JPH11220061A - Cavity-type semiconductor plastic package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cavity-type semiconductor plastic package which is superior in thermal dissipation and heat resistance, after moisture absorption. SOLUTION: This semiconductor plastic package of ball grid array using a metal printed wiring board and this cavity-type semiconductor plastic package, where a part of the metallic core is exposed at one part of the surface and a semiconductor chip fixed thereon and a circuit conductor around it, are connected with each other through wire boding and a metallic projection is exposed at one part of the rear face and the semiconductor part resin encapsulated. hereby, a cavity-type semiconductor plastic package of new structure which is superior in heat dissipation and heat resistance, after moisture absorption, etc., and suitable for mass production can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel semiconductor plastic package in which a plurality of semiconductor chips are mounted on a small printed wiring board. In particular, it relates to 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, as a semiconductor plastic package, a semiconductor chip such as a plastic ball grid array (P-BGA) or a plastic land grid array (P-LGA) is fixed on the upper surface of a plastic printed wiring board. It is connected to the conductor circuit formed on the upper surface of the printed wiring board by wire bonding, and the lower surface of the printed wiring board is formed with conductor pads for connection with the motherboard printed wiring board using solder balls, and the front and back circuit conductors are plated 2. Description of the Related Art A semiconductor plastic package having a structure in which a semiconductor chip is sealed with a resin by connecting through a formed through hole is known. In the known structure, a plated heat diffusion through hole is formed from the upper metal foil for fixing the semiconductor chip to the lower surface in order to diffuse the heat generated from the semiconductor to the motherboard printed wiring board. Through the through holes, moisture is absorbed by the resin adhesive containing silver powder used for fixing the semiconductor, and the interlayer blisters are heated by the heating at the time of mounting on the motherboard and the heating at the time of removing the semiconductor parts from the motherboard. There is a risk of this occurring, called the popcorn phenomenon. When this popcorn phenomenon occurs, the package often becomes unusable, and it is necessary to greatly improve this phenomenon. In addition, higher functionality and higher density of semiconductors mean more and more heat generation, and heat dissipation is insufficient with only through holes directly below the semiconductor chip for heat dissipation.

[0003]

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

[0004]

SUMMARY OF THE INVENTION According to the present invention, a semiconductor chip is fixed to a surface of a metal plate exposed at a substantially central concave portion on one side of a printed wiring board, and the semiconductor chip is formed on a surface of the printed wiring board surrounding the semiconductor chip. At least a signal propagation circuit conductor on the surface of the printed wiring board is formed to connect a circuit conductor formed on the opposite surface of the printed wiring board or a solder ball of the package. And a semiconductor plastic package having a structure in which at least the semiconductor chip is sealed with a resin, and a metal plate slightly larger than the printed wiring board is used for the printed wiring board. It is arranged at substantially the center in the thickness direction, and the metal plate is insulated from the front and back circuit conductors with the thermosetting resin composition. A clearance hole having a diameter larger than the diameter of at least one through-hole conductor is formed, a hole wall of the clearance hole is insulated, and a part of the metal plate is exposed to a substantially central outer surface of the printed wiring board used for fixing the semiconductor chip, In addition, a metal slightly larger than the area for fixing the semiconductor chip is exposed at least at one or more surfaces, and a metal plate is exposed as a protrusion on the back surface of the printed wiring board. Provided is a cavity-type semiconductor plastic package that emits light. The present inventors dissipate the generated heat by using a metal plate exposed on the outer periphery of the printed wiring board,
There is no moisture absorption from the lower surface of the semiconductor chip, and the heat resistance after moisture absorption, that is, the popcorn phenomenon can be greatly improved, and the heat dissipation can be greatly improved.In addition, it is suitable for mass production, new economical improvement The present inventors have found that a semiconductor plastic package having a simple structure can be obtained, and have completed the present invention.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the plastic package of the present invention, a metal plate having good heat dissipation is arranged at substantially the center in the thickness direction of a printed wiring board. By forming a hole having a diameter smaller than the diameter of the clearance hole formed in the metal plate and forming the hole substantially at the center of the embedded resin, the insulation with the metal plate is maintained.

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. The present invention is a method in which a metal plate serving as a metal core is firstly known in advance by a known etching method, cold machining, rolling irregular strip processing, and the like.
At least one or more projections having a size substantially equal to that of the semiconductor chip are formed for fixing the semiconductor chip. Then, a clearance 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 so that a conductive through hole on both sides can be formed.
A hole is formed in the metal core by a punching method, a drill, a laser, or the like. Heat generated from the semiconductor is conducted from the portion where the semiconductor chip is mounted to the entire metal plate. The heat is diffused directly from the metal plate on the back surface to the motherboard printed wiring board or the like.

The surface of the metal plate on which the protrusions and the through holes are formed may be subjected to a surface treatment for improving adhesion and electrical insulation such as oxidation treatment, formation of fine irregularities, and formation of a film by a known method, if necessary. Apply. Except for the surface of the metal plate on which the projections and the clearance holes are formed and on which the semiconductor chip is directly fixed, the insulating portion is formed of a thermosetting resin composition. The formation of the insulating portion by the thermosetting resin composition,
Using a prepreg or the like impregnated with a thermosetting resin composition in a semi-cured state and drying, a hole slightly larger than the area of the exposed metal part directly fixing the semiconductor chip and the area of the metal projection part on the back surface is punched out. This is placed on the front and back, and laminated and formed under heat and pressure. The thickness of the prepreg is made slightly higher than the height of the metal projection. During the heating and pressurizing steps, a semi-cured thermosetting resin that has been melted once by heat is poured into the clearance holes of the metal plate to fill the clearance holes, and at the same time, the thermosetting resin except for the surface of the metal protrusions Integrate with a resin composition. A hole may not be formed in the front side in advance, but a method of forming a cavity with a carbon dioxide laser or the like after molding to form a cavity may be used.

Further, a non-solvent or solvent-type thermosetting resin composition is used, and is applied to portions other than the metal plate projections by screen printing or the like. Then, it is cured by heating as it is, or is laminated and formed under heat and pressure to be integrated. In the case of laminating and molding, the resin is poured into the clearance holes and thermosetting at the same time as described above. In the case of coating and semi-curing, a resin is poured into the clearance hole at a low pressure, and the solvent or air is removed while heating, and semi-cured.
When the solvent is contained, since the unfilling in the clearance hole is likely to occur, a method of pouring the solvent-free liquid thermosetting resin composition into the clearance hole in advance and curing or semi-curing is generally used. In either method, processing is performed so that the inside of the clearance hole of the metal plate is filled with the thermosetting resin composition.

[0009] The side surface of the metal plate may be any of a shape embedded with a thermosetting resin composition and an exposed shape.

[0010] Further, in order to form a through-hole printed wiring board by the subtractive method, at the time of lamination molding,
A metal foil slightly larger than the printed wiring board or a single-sided copper-clad laminate is placed on the outermost layer on the front and back, and the front and back are covered with metal foil for forming the outer layer circuit by laminating under heat and pressure. The resulting metal foil-clad multilayer board 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.

A through hole for conducting the circuit on the front and back is formed in a portion of the plate prepared by the above subtractive method or semi-additive method other than the portion for fixing the semiconductor by a known method such as drilling, laser or plasma. Drill holes.

The through hole for the front and back signal circuits is formed substantially at the center of the metal plate clearance 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, and a plated through hole is formed.At the same time, in the full additive method, wire bonding terminals, signal circuits, solder ball pads,
Form conductor circuits and the like.

In the semi-additive method, the front and back surfaces are plated at the same time as the through holes are plated, and thereafter, circuits are formed on the upper and lower sides by a known method. In the case of lamination molding using front and back metal foils, the metal foil on the semiconductor chip fixing portion is also removed in the front and back circuit forming steps. If necessary, a desmear treatment is performed, metal plating is performed, and after forming the circuit, a noble metal plating is formed on at least the surface of the wire bonding pad and the solder ball connection pad on the opposite surface to complete the printed wiring board. In this case, a portion that does not require noble metal plating is covered with a plating resist in advance. Alternatively, after plating, a film is formed on at least the surface other than the bonding pad and the opposite surface of the solder ball connection pad with a known thermosetting resin composition or a photo-selective thermosetting resin composition as necessary. When using a single-sided metal foil-clad laminate, after forming the circuit,
Alternatively, after the noble metal plating, the base material on the mounting portion of the semiconductor chip and the metal protrusion on the back side is cut off with a router or the like.

An adhesive or a metal powder mixed adhesive is used on the surface of the metal projection portion of the printed wiring board to which the semiconductor is bonded,
The semiconductor chip is fixed, and the semiconductor chip and the bonding pads of the printed wiring board circuit are connected 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 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, and the ball is melt-connected by heat. When the P-LGA is made without attaching solder balls to the package, and mounted on the motherboard printed wiring board, the solder ball connection conductor pads formed on the motherboard printed wiring board surface and the solder ball conductors for the P-LGA The pads are connected by heating and melting the solder balls.

Although the metal plate used in the present invention is not particularly limited, a metal plate having a high elastic modulus, a high thermal conductivity and a thickness of 30 to 300 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, Gr, Zr, Zn, or the like, or a metal plate in which the surface of the alloy is plated with copper is preferably used.

The height of the metal projection of the present invention is 30 to 200 μm.
m is preferred. Further, it is preferable that the height of the prepreg formed by hollowing out the projection or the thermosetting resin formed by screen printing is the same as or slightly higher than the height of the projection. The area of the projection is equal to or greater than the area of the semiconductor chip, and is preferably slightly larger. Generally, it is 5 to 20 mm square. The metal protrusions can be formed by a generally known method such as etching, cold machining, or rolling irregular shape processing. In addition, on a smooth metal plate, homogeneous of a predetermined size,
Or a foreign metal plate, such as copper paste with good thermal conductivity,
It is also possible to form projections by bonding with a generally known bonding method.

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-dicyanashibiphenyl, 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 43-184
68, 44-4791, 45-11712, 46-41112, 47-26853
And polyfunctional cyanate compounds described in JP-A-51-63149 and the like can also be used. A prepolymer having a molecular weight of 400 to 6,000 and having a triazine ring formed by trimerizing a cyanato group of these polyfunctional cyanate compounds is 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, these prepolymers are 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 group-containing silicone resin with an ephalohydrin, 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 may be used alone, but it is preferable to use them in combination as appropriate 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, fluoro rubber, 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 copolymer; polycarbonate, High molecular weight prepolymers or oligomers such as 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. Therefore, a known thermosetting resin is used for the thermosetting resin used. A catalyst may be used. Use amount is thermosetting resin 10
0.005 to 10 parts by weight, preferably 0.01 to 5 parts by weight per 0 parts by weight
Parts by weight.

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. Further, a film obtained by applying a thermosetting composition to the front and back of a film such as a polyimide film and heating to a semi-cured state can also be used.

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

The diameter of the clearance hole 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 wall is insulated by the thermosetting resin composition. The diameter of the through hole for front / back conduction is not particularly limited, but is 50 to 300 μm.
Is preferred.

When preparing a prepreg for a multilayer 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, high flow, low flow, or no flow is performed depending on the degree of the semi-cured state. 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 50 μm or less.
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 to 60 minutes, depending on the degree of the desired flow,
Select as appropriate.

The method for producing the semiconductor plastic package containing the metal core of the present invention is not particularly limited. For example, the following method (FIG. 1) is used. (1) The entire surface of the metal plate serving as the inner layer is coated with a liquid etching resist, heated to remove the solvent, and then covered with a negative film formed so that the resist of the heat radiating portion on the outer peripheral portion remains. Unexposed portions are dissolved and removed with an aqueous solution of sodium carbonate. (2) After the metal plate is dissolved to a predetermined thickness by etching, the etching resist is dissolved and removed. (3) The upper and lower surfaces are again covered with a liquid etching resist, and a negative film prepared so as to block the light in the clearance hole is placed thereon and exposed with ultraviolet light. (4) After dissolving and removing the etching resist in the clearance hole, etching is performed from both sides by an etching method to form a clearance hole in the metal plate. (5) After removing the etching resist, the entire surface of the metal plate is subjected to chemical surface treatment, the unprocessed prepreg is placed on the surface on which the semiconductor chip is mounted, and the metal projections on the back side are slightly larger than the projections. Dispose the opened prepreg and put metal foil on the top and bottom. (6) After laminating under heat, pressure, and vacuum, drill through holes to prevent through holes from contacting the inner metal foil, apply desmear treatment, and metal plating. I do. (7) At the same time as forming a circuit up and down by a known method, the metal foil on the metal plate protrusion is removed. Drill holes at the locations where semiconductor chips are mounted
Desmearing is performed if necessary. After coating with a plating resist, precious metal plating is performed, a semiconductor chip is bonded to the surface of the inner layer metal plate, which is a semiconductor chip mounting portion, wire bonding is performed, and then resin sealing is performed, and a solder ball is bonded as necessary.

[0032]

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 prepare a prepolymer. Obtained. 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, and the mixture is dissolved and mixed, and an inorganic filler (trade name: calcined talc BST-200, Nippon Talc Co., Ltd.) is added.
Varnish A was obtained by uniformly mixing with stirring.
This varnish is impregnated with a glass woven fabric having a thickness of 100 μm and dried at 150 ° C., and the gel time (at 170 ° C.) is 7 seconds, 170 ° C., 20 kgf /
The resin was prepared so as to have a resin flow of 110 μm in 5 minutes in cm ² , and a prepreg (prepreg B) in a semi-cured state having a thickness of 105 μm was obtained. In addition, gelation time 114 seconds, resin flow 13 mm,
A prepreg C having a thickness of 109 μm was prepared. On the other hand, a copper plate having a thickness of 250 μm serving as an inner metal plate was prepared, and a 13 mm square, 100 μm height projection was formed at the center of the back surface of a 50 mm square package. After that, a liquid etching resist was applied to the entire surface of the metal plate at a thickness of 20 μm, dried, and the solvent was blown off.
The protrusions were cut out, a negative film through which ultraviolet light was transmitted was laminated on the back surface except for the clearance hole, and the surface except the clearance hole was irradiated with ultraviolet light, and then the resist film in the clearance hole was removed with a 1% aqueous solution of sodium carbonate. A 0.6 mmφ clearance hole was opened from both sides by etching. A black copper oxide treatment is applied to the entire surface of the metal plate, and the prepreg B having a hole 50 μm larger than the protruding portion formed by a router is covered on the back surface at a position corresponding to the protruding portion, and the prepreg C is covered on the front surface. , Place 18μm thick electrolytic copper foil on both outer sides, 200 ℃, 20kgf / c
^They were laminated and molded under a vacuum of m ² , 30 mmHg or less for 2 hours, and integrated. Drill a 0.25mm through hole in the center of the clearance hole so that it does not come into contact with the metal in the clearance hole.After desmearing, copper plating is performed by electroless and electrolytic plating. A copper plating layer was formed. Apply liquid etching resist on both sides,
After drying, the positive film was overlaid and exposed and developed to form a front and back circuit, and the copper foil on the protrusion was simultaneously removed by etching to obtain a printed wiring board. After forming a plating resist other than the projection, the bonding pad and the ball pad, applying nickel and gold plating, zag the place where the semiconductor chip on the surface is fixed with a counterbore machine,
A printed wiring board with the metal exposed was prepared. After bonding and fixing a 13mm square semiconductor chip to the exposed metal part with silver paste, wire bonding is performed, and then using a liquid epoxy sealing resin containing silica, the semiconductor chip part is resin-sealed to form a semiconductor package. (FIG. 1).
Table 1 shows the evaluation results of this package.

Example 2 Using one prepreg C, an 18 μm electrolytic copper foil was placed on one side and a release film was placed on one side, and the pressure was increased at 200 ° C. and 20 kgf / cm ² .
A single-sided copper-clad laminate was prepared by lamination molding for a time. 250.mu.m thick Cu: 99.86% by weight, Fe: 0.11% by weight,
P: 0.03% by weight of an alloy plate was processed in the same manner as in Example 1 to form two protrusions on the surface, a size of 10 mm square, a height of 100 μm, and a protrusion of 5 mm on the outer periphery and a height of 100 μm. . 0.6 m
Drill a clearance hole of mφ, similarly place a prepreg B with a hole in the protrusion with a router on the back side, place a prepreg C on the front side, put the single-sided copper clad laminate obtained above on both sides, Lamination molding was performed under the same conditions. Drill a 0.20mm through hole in the center with a drill so as not to contact the metal of the clearance hole part, and after desmearing, perform copper plating by electroless and electrolytic plating. A copper plating layer was formed. A liquid etching resist was applied to the front and back, and the solvent was removed by drying. Then, a positive film was overlaid, exposed and developed to form a front and back circuit. After forming a plating resist other than the bonding pad and ball pad, applying nickel and gold plating, the laminate on the copper plate protrusion and the base material on the semiconductor chip mounting part are all cut and removed with a router,
The printed wiring board with the exposed metal was completed. After that, the semiconductor chip is bonded and wire-bonded in the same manner,
A semiconductor package was obtained by resin sealing. Table 1 shows the evaluation results.
Shown in

Comparative Example 1 Two prepregs C of Example 1 were used, and electrolytic copper foils were arranged on the upper and lower sides, and laminated and formed at 200 ° C., 20 kgf / cm ² under vacuum for 2 hours to form a double-sided copper-clad laminate. Obtained. 0.25mmφ hole diameter at specified position
Was drilled and copper plated after desmear treatment. Circuits were formed on and under the plate by a known method, and nickel plating and gold plating were performed. 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. Stopped (FIG. 2). Table 1 shows the evaluation results of this package.

COMPARATIVE EXAMPLE 2 A semiconductor chip mounting portion of the printed wiring board of Comparative Example 1 was hollowed up and down with a counterbore machine.
Using a prepreg B, a μm copper plate was similarly adhered 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. 3). Table 1 shows the evaluation results of this package.

Test methods for various characteristics are shown below. <Measurement method> 1) Heat resistance after moisture absorption ・ JEDEC STANDARD TEST METHOD A113-A LEVEL3: 30 ℃ ・ 60% R
After treatment with H 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. 2) Electric insulation after moisture absorption ・ JEDEC STANDARD TEST METHOD A113-A LEVEL2: 85 ℃ ・ 60% R
After treatment with H 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 DMA method. 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 them and laminated and molded in the same manner at 121 ° C. After the treatment at 2 atm for a predetermined time, post-treatment was performed at 25 ° C. and 60% RH for 2 hours, and the insulation resistance between the terminals was measured 60 seconds after 500 VDC was applied. 5) Migration resistance Using the test piece of 4) above, the insulation resistance between terminals was measured by applying 50 VDC at 85 ° C. and 85% RH. 6) Heat dissipation The package was bonded to the same motherboard printed wiring board with solder balls and used continuously for 800 hours before measuring the package temperature. 7) Temperature cycle test JEDEC STANDARD JESD22-A104-A CONDITION C (-65 ℃
・ 30 minutes ← → room temperature 5 minutes ← → + 150 ℃ ・ 30 minutes) 1 cycle.

[0038]

[Table 1]

[0039]

According to the present invention, a semiconductor chip is fixed to a surface of a metal plate exposed in a substantially central recess on one side of a printed wiring board.
The semiconductor chip and the circuit conductor formed on the surface of the printed wiring board around the semiconductor chip are connected by wire bonding, and at least the signal propagation circuit conductor on the surface of the printed wiring board is connected to the circuit conductor formed on the opposite surface of the printed wiring board. Alternatively, the printed circuit board is a semiconductor plastic package having a structure in which circuit conductor pads formed for connecting solder balls of the package are connected by plated through holes, and at least a semiconductor chip is sealed with a resin. A metal plate slightly larger than the wiring board is arranged at substantially the center in the thickness direction of the printed wiring board, and the metal plate is insulated from the front and back circuit conductors with a thermosetting resin composition. Forming a clearance hole with a diameter larger than the hole conductor diameter, insulating the hole wall of the clearance and the metal plate with a resin composition, Is exposed on the outer surface substantially at the center of the printed wiring board used for fixing the semiconductor chip, and at least one surface of a metal slightly larger than the area for fixing the semiconductor chip is exposed on the surface. By exposing the metal plate as a protrusion on the back surface of the wiring board, and by using this exposed metal plate to dissipate heat, the cavity type semiconductor plastic package is characterized by:
There is no moisture absorption from the lower surface of the semiconductor chip, and the heat resistance after moisture absorption, that is, the popcorn phenomenon can be significantly improved, the heat dissipation can be improved, the reliability is excellent, and in addition, it is suitable for mass productivity. A semiconductor plastic package having a novel cavity structure with improved economy was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a manufacturing process of a cavity type semiconductor plastic package of the present invention.

FIG. 2 shows a schematic cross-sectional view of a conventional semiconductor plastic package manufacturing process manufactured in Comparative Example 1.

FIG. 3 is a schematic cross-sectional view of a conventional semiconductor plastic package manufacturing process manufactured in Comparative Example 2.

[Explanation of symbols]

 (a) Liquid etching resist (b) Metal plate (c) Negative film (d) Clearance hole (e) Metal foil (f) Pre-preg B (g) Pre-preg C (h) Through-hole for front / back circuit conduction (i) Semiconductor chip (j) Silver paste (k) Gold wire (l) Sealing resin (m) Solder ball (n) Plating resist (o) Heat dissipation through hole

Claims (3)

[Claims] 1. A semiconductor chip is fixed to a surface of a metal plate exposed in a substantially central recess on one side of a printed wiring board,
The semiconductor chip and the circuit conductor formed on the surface of the printed wiring board around the semiconductor chip are connected by wire bonding, and at least the signal propagation circuit conductor on the surface of the printed wiring board is connected to the circuit conductor formed on the opposite surface of the printed wiring board. Alternatively, the printed circuit board is a semiconductor plastic package having a structure in which circuit conductor pads formed for connecting solder balls of the package are connected by plated through holes, and at least a semiconductor chip is sealed with a resin. A metal plate slightly larger than the wiring board is arranged at substantially the center in the thickness direction of the printed wiring board, and the metal plate is insulated from the front and back circuit conductors with a thermosetting resin composition. A clearance hole having a diameter larger than the diameter of the hole conductor is formed, the hole wall of the clearance hole is insulated, and one part of the metal plate is half A metal which is exposed on the outer surface substantially at the center of the printed wiring board used for fixing the body chip, and is slightly larger than the area for fixing the semiconductor chip, is exposed on at least one surface, and further, the back surface of the printed wiring board A cavity-type semiconductor plastic package, wherein a metal plate is exposed as a projection and heat is dissipated using the exposed metal plate. 2. The cavity-type semiconductor plastic package according to claim 1, wherein said metal plate is made of a copper alloy containing 95% by weight or more of copper or pure copper. 3. The cavity type 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.