JP2013098270A - Substrate, semiconductor device, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for resin seal-type semiconductor device which allows good thermal conductivity and insulation property to be obtained with stability, and which is excellent in terms of productivity, and to provide a resin seal-type semiconductor device and a method of manufacturing the same.SOLUTION: The metal base substrate 1 comprises: a metal base material 2; and an insulator layer 3b of B stage state formed on the metal base material by use of an epoxy resin composition. The epoxy resin composition includes at least an epoxy resin, a UV light-curing type setting agent and a heat-curing type setting agent, or a heat UV light-curing type setting agent, and an inorganic filler; the content of the inorganic filler is 50-80 vol.%.

Description

  The present invention relates to a resin-encapsulated semiconductor device substrate, a resin-encapsulated semiconductor device using the substrate, and a method for manufacturing the same. More specifically, the present invention relates to a technology for manufacturing a resin-encapsulated semiconductor device.

  In general, a resin-encapsulated semiconductor device on which a power semiconductor that generates a large amount of heat is mounted uses a metal base substrate that has excellent heat dissipation performance (see, for example, Patent Document 1). In such a semiconductor device, for example, a lead frame on which a power semiconductor is mounted is fixed to a thermally conductive insulating layer formed on a metal base material, and the back surface (metal base material) of the metal base substrate is externally provided. The power semiconductor is sealed with a mold resin so as to be exposed to the surface.

  In the power semiconductor device described in Patent Document 1, reliability is improved by forming a mixed layer in which the respective materials are mixed at the interface between the insulating layer and the mold resin. Conventionally, a method for manufacturing a resin-encapsulated semiconductor device in which an insulating layer of a metal base substrate is in a B-stage state and the mold resin is integrally cured by heating at the time of sealing has been proposed (for example, Patent Documents). (See 2, 3)

Japanese Patent Laying-Open No. 2005-150595 (Japanese Patent No. 4146785) JP 2002-314004 A JP 2007-142346 A

  However, the conventional techniques described above have the following problems. That is, in the conventional resin-encapsulated semiconductor device described in Patent Document 1, a mixed layer is formed at the interface between the insulating sheet and the mold resin, but such an insulating sheet has a low degree of curing. Therefore, when the lead frame and the insulating sheet are joined, there is a problem that the lead frame is buried in the insulating layer and the insulating property is impaired. Further, the resin-encapsulated semiconductor device substrates described in Patent Documents 2 and 3 have excellent heat dissipation characteristics and good productivity. However, when fixing the lead frame, one of the lead frames is attached to the insulating layer. The portion may be buried, the insulating layer may be thinned, and the withstand voltage may be reduced.

  Accordingly, the present invention provides a substrate for a resin-encapsulated semiconductor device, a resin-encapsulated semiconductor device, and a method for manufacturing the same, in which excellent thermal conductivity and insulating properties are stably obtained and productivity is excellent. The main purpose.

The resin-encapsulated semiconductor device substrate according to the present invention is a metal base substrate in which an insulating layer is laminated on a metal base material, and the insulating layer includes at least an epoxy resin, an ultraviolet curable curing agent, and a heat. It is formed of an epoxy resin composition containing a curable curing agent or a thermal ultraviolet curable curing agent and an inorganic filler, and the inorganic filler content is 50 to 80% by volume, and is in a B stage state It is.
In this substrate, the ultraviolet curable curing agent may be a cationic polymerization catalyst.
Moreover, as an inorganic filler, the coarse powder with an average particle diameter of 10-50 micrometers and the fine powder with an average particle diameter of 0.5-4.0 micrometers can be used, for example.
Alternatively, as the inorganic filler, coarse powder having an average particle diameter of 30 to 50 μm, medium powder having an average particle diameter of 5 to 20 μm, and fine powder having an average particle diameter of 0.5 to 4.0 μm can be used. .
Furthermore, the thickness of the insulating layer can be set to, for example, 50 to 300 μm.
Furthermore, a conductor layer or a conductor circuit may be formed on the insulating layer.

  A resin-encapsulated semiconductor device according to the present invention includes a resin-encapsulated semiconductor device substrate according to any one of claims 1 to 5 and a lead frame fixed on an insulating layer of the metal base substrate. And a semiconductor chip mounted on the lead frame, and at least the semiconductor chip is sealed with a resin.

  The method for producing a resin-encapsulated semiconductor device according to the present invention includes at least an epoxy resin, an ultraviolet curable curing agent and a thermosetting curing agent, or a thermal ultraviolet curable curing agent, and an inorganic filler on a metal base material. A step of forming a B-stage insulating layer by using an epoxy resin composition containing 50-80% by volume of the inorganic filler and obtaining a metal base substrate; and the B-stage insulating layer A lead frame is disposed thereon, the step of irradiating ultraviolet rays toward the insulating layer from above, the step of heating while applying pressure between the lead frame and the metal base material, and the lead frame A step of mounting a semiconductor chip and a substrate on which the semiconductor chip is mounted are placed in a mold, and a mold resin is injected into the mold and then heated to cure the mold resin and the insulating layer. And a step in which, the.

  According to the present invention, since the surface of the insulating layer where the lead frame is not laminated is completely cured by ultraviolet rays, the lead frame is prevented from being buried in the insulating layer, and the thermal conductivity and the insulation are deteriorated. Can be prevented.

It is a figure which shows typically the structure of the metal base substrate which concerns on the 1st Embodiment of this invention. It is a figure which shows typically the structure of the metal base circuit board which concerns on the 2nd Embodiment of this invention. It is a figure which shows typically the structure of the resin-encapsulated semiconductor device which concerns on the 3rd Embodiment of this invention. (A)-(d) is a figure which shows the manufacturing method of the semiconductor device 21 shown in FIG. 3 in the order of the process.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.

(First embodiment)
First, the substrate according to the first embodiment of the present invention will be described. FIG. 1 is a diagram schematically showing a configuration of a metal base substrate according to the first embodiment of the present invention. The metal base substrate 1 of this embodiment is used for a resin-encapsulated semiconductor device, and an insulating layer 3b in a B stage state is formed on a metal base material 2 as shown in FIG. Moreover, the conductor foil 4 may be laminated | stacked on the insulating layer 3b as needed.

[Metal base material 2]
The material of the metal base material 2 is not particularly limited, but aluminum, iron, copper, stainless steel or an alloy thereof is preferable, and among these, copper is particularly preferable because of excellent heat dissipation. Moreover, as for the metal base material 2, it is desirable that Ni-P plating is given to the non-adhesion surface in order to prevent oxidation. Further, in order to improve the adhesion with the insulating layer 3b, it is desirable that the surface to be bonded to the insulating layer 3b is subjected to a roughening treatment by etching or various platings. Since the chemical conversion treatment using is highly effective in improving the adhesion to the insulating layer 3b, it is suitable for the surface treatment of the metal base material 2.

[Insulating layer 3b]
The insulating adhesive layer 3b is formed of an epoxy resin composition containing at least an epoxy resin, two types of curing agents, an ultraviolet curable type and a thermosetting type, and an inorganic filler, and is in a B stage state. . Here, the “B stage state” refers to a semi-cured state in which the curing reaction of the epoxy resin is stopped halfway. Specifically, it refers to a solid state at room temperature (25 ° C.) and remelted when heated at a high temperature (60 ° C. or higher), and quantitatively refers to a state where the curing rate is 5 to 80%.

<Epoxy resin>
Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyfunctional epoxy resin (cresol borac epoxy resin, dicyclopentadiene type epoxy resin, etc.), cyclic aliphatic epoxy resin, glycidyl ester type epoxy. Resin, glycidylamine type epoxy resin, etc. can be used. Among them, bisphenol A or F-type epoxy resin having a balanced property including adhesiveness, heat resistance, electrical properties, flexibility, and cost is preferable, and a resin having an epoxy equivalent of 100 to 1000 is particularly preferable. .

<Ultraviolet curing type curing agent or thermal ultraviolet curing type curing agent>
As the ultraviolet curable curing agent or the thermal ultraviolet curable curing agent, sulfonium or the like can be used. Among these curing agents, cationic polymerization catalysts such as onium salts and vistonium salts are particularly preferred from the viewpoint of curing speed and deep part curability. In addition, the compounding quantity of a ultraviolet curable hardening agent and a thermal ultraviolet curable hardening | curing agent is not specifically limited, According to the kind of epoxy resin, use conditions, etc., it can select suitably.

Examples of the cationic polymerization catalyst include onium salts, iron-arene complexes, and sulfonic acid esters. For example, the ultraviolet curable onium salt has a general formula of diaryl iodonium salt Ar ₂ I ⁺ · X ⁻ , triarylsulfonium salt Ar ₃ S ⁺ · X ⁻ , triaryl selenonium salt Ar ₃ Se ⁺ · X ⁻ , tetra This is a compound represented by an arylphosphonium salt Ar ₄ P ⁺ .X ⁻ . Here, aryl (Ar) is a benzene ring having one or two substituents or an unsubstituted benzene ring.

In addition, examples of the substituent include linear or branched alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, octyl, decyl, dodecyl, tetradecyl, and tert-butyl groups, and cycloalkyl groups such as cycloalkyl. Monovalent substituted carbons such as aryl groups such as phenyl and naphthyl, alkaryl groups such as tolyl and xylyl, aralkyl groups such as benzyl and 2-phenylethyl, and alkenyl groups such as vinyl, allyl and butenyl Examples include a hydrogen group, an alkoxyl group such as methoxy, ethoxy, propoxy, and tert-butoxy group, a nitro group, a cyano group, and a CH ₃ CONH group. Counter anions include SbF ₆ ⁻ , AsF ₆ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , FSO ₃ ⁻ , F ₂ PO ₂ ⁻ and [B (C ₆ F ₅ )] ^−. Illustrated. Among these onium salts, iodonium salts and sulfonium salts are particularly preferable because of their excellent curability, and the counter anions are PF ₆ ⁻ and [B (C ₆ F ₅ )] ⁻ which are less toxic and hardened. Excellent in properties.

  Such preferred onium salts include diphenyltodonium, phenyl (4-t-butylphenyl) iodonium, di (4-tolyl) iodonium, di (4-hydroxyphenyl) iodonium, di (4-methoxyphenyl) iodonium, di Iodonium such as (4-ethoxyphenyl) iodonium, di (acetoxyphenyl) iodonium, (4-hydroxyphenyl) benzyliodonium, di (4-cumyl) iodonium, (4-methoxyphenyl) -1-naphthylmethyliodonium; triphenyl Sulfonium, diphenyl (4-t-butylphenyl) sulfonium, tolylylsulfonium, tris (4-hydroxyphenyl) sulfonium, tris (4-methoxyphenyl) sulfonium, tris (4-ethoxyphene) E) salts of hexafluorophosphate such as sulfonium, tris (acetoxyphenyl) sulfonium, methyl (4-hydroxyphenyl) benzylsulfonium, methyl (4-methoxyphenyl) -1-naphthylmethylsulfonium, tetrakis (pentafluorophenyl) A salt with boron is preferred.

<Thermosetting curing agent>
The thermosetting curing agent is not particularly limited, and can be appropriately selected from epoxy resin curing agents.

<Inorganic filler>
The inorganic filler blended in the epoxy resin composition only needs to be electrically insulating and have good thermal conductivity. For example, silica, alumina, aluminum nitride, silicon nitride, boron nitride, boron nitride, magnesium oxide, oxidation Beryllium or the like can be used.

  However, when the blending amount of the inorganic filler is less than 50% by volume of the whole composition, the electric insulation and thermal conductivity are insufficient, and when it exceeds 80% by volume, the viscosity becomes high and the withstand voltage is increased. And adhesiveness decreases. Therefore, the inorganic filler content in the epoxy resin composition is 50 to 80% by volume.

  Moreover, it is preferable that the inorganic filler mix | blended with an epoxy resin composition mixes and uses the 2 or more types of inorganic filler from which a particle size differs. Specifically, it is preferable to use a coarse powder having an average particle size of 10 to 50 μm and a fine powder having an average particle size of 0.5 to 4.0 μm. Furthermore, you may use the coarse powder whose average particle diameter is 30-50 micrometers, the medium powder whose average particle diameter is 50-20 micrometers, and the fine powder whose average particle diameter is 0.5-4.0 micrometers.

<Thickness of insulating layer 3b>
The thickness of the insulating adhesive layer 3b in the B stage state is preferably 50 to 300 μm from the viewpoint of withstand voltage and heat dissipation characteristics. When the thickness of the insulating adhesive layer 3b is less than 50 μm, it may be difficult to obtain a desired withstand voltage value, and when the thickness of the insulating adhesive layer 3b exceeds 300 μm, the thermal resistance increases and heat dissipation. The characteristics may deteriorate.

[Conductor foil 4]
For the conductor foil 4, for example, a foil material or a clad foil made of aluminum, iron, copper, stainless steel or an alloy thereof can be used, and in particular, a copper foil is used from the viewpoint of electrical conductivity and heat dissipation. Is preferred. Various surface treatments such as degreasing treatment, sandblasting, etching, various plating treatments, primer treatment using a coupling agent, etc. on the adhesive surface with the insulating adhesive layer 3b in order to improve the adhesion with the insulating layer 3b. It is desirable that

[Production method]
The metal base substrate 1 of the present embodiment may form the insulating layer 3b by applying the epoxy resin composition described above on the metal base material 2 and then heating and curing to the B stage state. A composition formed into a sheet shape may be laminated on the metal base material 2 to form the insulating layer 3b. In this case, the material that has been heated to the B stage state in advance may be laminated on the metal base material 2, but may be laminated on the metal base material 2 and then heated to the B stage state. The metal foil 4 may be laminated after the insulating layer 3b is in the B stage state.

  As described above in detail, the metal base substrate 1 according to the present embodiment includes an insulating layer 3b containing an ultraviolet curable curing agent and a thermosetting curing agent, or a thermal ultraviolet curable curing agent. When fixing, the surface of the insulating layer where the lead frame is not laminated can be completely cured by irradiating with ultraviolet rays. This can prevent the lead frame from sinking into the insulating layer without complicating the manufacturing process.

(Second Embodiment)
Next, a circuit board according to a second embodiment of the present invention will be described. FIG. 2 is a diagram schematically showing a configuration of a metal base circuit board according to the second embodiment of the present invention. 2, the same components as those of the metal base substrate shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The metal base circuit board 11 of this embodiment is used for a resin-encapsulated semiconductor device, and a conductor circuit 4a is formed on an insulating layer 3b of the metal base board 1 as shown in FIG. . The pattern formation method of the conductor circuit 4a is not specifically limited, A well-known method, such as etching the metal foil 4 with an acid etc., can be applied.

  As described in detail above, in the metal base circuit board 11 of the present embodiment, the insulating layer 3b is blended with an ultraviolet curable curing agent and a thermosetting curing agent, or a thermal ultraviolet curable curing agent, so By irradiating, the surface of the insulating layer in the portion where the conductor circuit 4a is not laminated can be completely cured. Thereby, sinking at the time of mounting can be prevented without complicating the manufacturing process. The other configurations and effects of the metal base circuit board 11 of the present embodiment are the same as those of the first embodiment described above.

(Third embodiment)
Next, a resin-encapsulated semiconductor device (hereinafter simply referred to as a semiconductor device) according to a third embodiment of the present invention will be described. FIG. 3 is a diagram schematically showing the configuration of the semiconductor device of this embodiment. In FIG. 3, the same components as those of the metal base substrate shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. As shown in FIG. 3, in the semiconductor device 21 of this embodiment, a semiconductor chip 23 is mounted on the lead frame 22 fixed to the metal base substrate 1 of the first embodiment described above, and this semiconductor chip 23 is molded. It is sealed with resin 24.

  In the semiconductor device 21, the insulating layer 3c of the metal base substrate 1 is in a C stage state, and a lead frame is fixed thereon. Here, the “C stage state” refers to a state in which the reaction between the epoxy resin and the curing agent in the insulating adhesive is almost finished and is insoluble and infusible. Specifically, when heat curing is performed by DSC (Differential Scanning Calorimeter), almost no heat generation can be observed, and the curing rate is 80% or more.

  Further, the method for connecting the semiconductor chip 23 and the lead frame 22 in the semiconductor device 21 of the present embodiment is not particularly limited, and for example, a wire bonding method or the like can be applied.

[Production method]
Next, a method for manufacturing the semiconductor device 21 of this embodiment will be described. 4A to 4D are views showing a method of manufacturing the semiconductor device 21 shown in FIG. When manufacturing the semiconductor device 21 of this embodiment, first, as shown in FIG. 4A, the lead frame 22 is disposed on the metal base substrate 1.

  Then, as shown in FIG. 4B, ultraviolet rays are irradiated from above the lead frame 22 toward the metal base substrate 1. As a result, the surface of the portion of the insulating layer where the lead frame 22 is not laminated is completely cured.

  Next, as shown in FIG. 4C, heating is performed while applying pressure between the lead frame 22 and the metal base substrate 1. At this time, since the insulating layer is cured by the above-described ultraviolet irradiation, only the insulating layer directly under the lead frame 22 is melted. Thereby, it is possible to prevent the lead frame 22 from being buried in the insulating layer.

  Subsequently, the semiconductor chip 23 is mounted on the lead frame 22 via solder or the like, and the lead frame 22 and the semiconductor chip 23 are connected by wire bonding or the like. Thereafter, the metal base substrate 1 on which the semiconductor chip 23 is mounted is placed in the mold die, and the mold resin is injected into the cavity of the mold die so that the mold resin and the insulating layer 2b of the metal base substrate 1 are completely formed. Curing is performed to obtain the semiconductor device 21 shown in FIG.

  As described above in detail, the semiconductor device 21 of the present embodiment has excellent thermal conductivity and insulating properties and excellent productivity because the burying of the lead frame in the insulating layer is suppressed.

DESCRIPTION OF SYMBOLS 1, 11 Metal base substrate 2 Metal base material 3b Insulating layer in B stage state 3c Insulating layer in C stage state 4 Conductor foil 4a Conductor circuit 21 Semiconductor device 22 Lead frame 23 Semiconductor chip 24 Mold resin

Claims (9)

A metal base substrate in which an insulating layer is laminated on a metal base material,
The insulating layer contains at least an epoxy resin, an ultraviolet curable curing agent and a thermosetting curing agent, or a thermal ultraviolet curable curing agent, and an inorganic filler, and the content of the inorganic filler is 50 to 80 volumes. % Of a resin-encapsulated semiconductor device substrate that is formed of an epoxy resin composition and is in a B-stage state.   The resin-encapsulated semiconductor device substrate according to claim 1, wherein the ultraviolet curable curing agent is a cationic polymerization catalyst.   3. The resin-encapsulated semiconductor device according to claim 1, wherein the inorganic filler is a coarse powder having an average particle diameter of 10 to 50 [mu] m and a fine powder having an average particle diameter of 0.5 to 4.0 [mu] m. Substrate.   The inorganic filler is a coarse powder having an average particle size of 30 to 50 µm, a medium powder having an average particle size of 5 to 20 µm, and a fine powder having an average particle size of 0.5 to 4.0 µm. Item 3. A substrate for resin-encapsulated semiconductor device according to Item 1 or 2.   The resin-encapsulated semiconductor device substrate according to claim 1, wherein the insulating layer has a thickness of 50 to 300 μm.   The resin-encapsulated semiconductor device substrate according to claim 1, wherein a conductor layer is laminated on the insulating layer.   The resin-encapsulated semiconductor device substrate according to claim 1, wherein a conductor circuit is formed on the insulating layer. A substrate for a resin-encapsulated semiconductor device according to any one of claims 1 to 5,
A lead frame fixed on the insulating layer of the metal base substrate;
A semiconductor chip mounted on the lead frame,
A resin-encapsulated semiconductor device in which at least a semiconductor chip is encapsulated with resin. The metal base material contains at least an epoxy resin, an ultraviolet curable curing agent and a thermosetting curing agent, or a thermal ultraviolet curable curing agent, and an inorganic filler, and the content of the inorganic filler is 50 to 80. A step of forming a B-stage insulating layer with a volume% epoxy resin composition to obtain a metal base substrate;
A step of placing a lead frame on the insulating layer in the B-stage state and irradiating ultraviolet rays toward the insulating layer from above;
Heating while applying pressure between the lead frame and the metal base material;
Mounting a semiconductor chip on the lead frame;
Placing the substrate on which the semiconductor chip is mounted in a mold, injecting mold resin into the mold and then heating to cure the mold resin and insulating layer;
A method for manufacturing a resin-encapsulated semiconductor device comprising:

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