Temporary protective film for semiconductor sealing molding

Abstract

The present invention discloses a temporary protective film (10) for semiconductor sealing molding, which comprises a support film (1) and an adhesive layer (2) disposed on the support film (1) and containing acrylic rubber. The solid shear elastic modulus of the temporary protective film (10) for semiconductor sealing molding at 200° C. can be 5.0 MPa or more.

Description

Technical Field

[0001] The present invention relates to a temporary protective film for semiconductor sealing and molding, a lead frame with a temporary protective film, a sealing molding with a temporary protective film, and a method for manufacturing a semiconductor device. Background Art

[0002] The following structure has been used for semiconductor packages: a semiconductor element is bonded to a chip pad using an adhesive such as silver paste, and after it is joined to a lead frame using a wire, the external leads for external connection remain and the whole is sealed. However, with the increasing requirements for high density, small area, and thinness of semiconductor packages in recent years, semiconductor packages of various structures have been proposed. As such a semiconductor package, a semiconductor package (such as a QFN (Quad Flat Non-leaded) package) has been developed in which only one side of the package (the semiconductor element side) is sealed and the back side of the lead frame is exposed for external connection. According to the semiconductor package of this structure, since the lead frame does not protrude from the sealing resin, it is possible to achieve a small area and thinness. However, sometimes during the sealing molding, undesirable situations may occur such as the sealing resin wrapping around the back side of the lead frame.

[0003] As a method for preventing such an undesirable situation, the following method is known: a semiconductor adhesive film is adhered to the back side of a lead frame as a temporary protective film to protect the back side of the lead frame, and after sealing and molding the semiconductor element mounted on the surface side of the lead frame, the temporary protective film is peeled off (for example, Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2001 / 035460 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] Temporary protective films used in semiconductor sealing molding are expected to be attached to lead frames at low temperatures such as room temperature and to be easily peeled off after sealing. However, for example, the adhesive film for semiconductors disclosed in Patent Document 1 requires high temperature and high pressure conditions (e.g., 200-250°C, 3-8 MPa) to be attached to the back of the lead frame, and it is difficult to attach the adhesive film at room temperature (conditions where the temperature is not intentionally controlled, e.g., 24°C).

[0009] In addition, the semiconductor adhesive film of Patent Document 1 is preferably subjected to a heat treatment for peeling after sealing. On the other hand, in the case of a film having relatively good adhesiveness at room temperature, when peeling from a lead frame and a sealing material after sealing, adhesive residue may sometimes be generated on the lead frame side, and there is still room for improvement in terms of peelability after sealing molding.

[0010] Therefore, an object of the present invention is to provide a temporary protective film for semiconductor sealing molding which can be attached to a lead frame at room temperature and can be easily peeled off from the lead frame and the sealing layer while suppressing adhesive residue after sealing molding.

[0011] Means for solving technical problems

[0012] The present inventors have conducted intensive studies to solve the above-mentioned technical problems, and as a result, have found that the above-mentioned technical problems can be solved by using a specific adhesive layer, thereby completing the present invention.

[0013] One aspect of the present invention relates to a temporary protective film for semiconductor sealing molding, comprising a support film and an adhesive layer provided on the support film and containing acrylic rubber, wherein the temporary protective film has a solid shear elastic modulus of 5.0 MPa or more at 200°C.

[0014] The adhesive layer may further contain a releasability-imparting agent. The content of the releasability-imparting agent may be 10 parts by mass or more and less than 60 parts by mass based on 100 parts by mass of the acrylic rubber.

[0015] The thickness of the adhesive layer may be greater than or equal to 1 μm and less than or equal to 5 μm.

[0016] The supporting film may be a polyimide film.

[0017] The acrylic rubber may be a copolymer containing at least one monomer unit selected from butyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, (meth)acrylic acid, acrylonitrile, 2-hydroxyethyl (meth)acrylate, and glycidyl (meth)acrylate. The weight average molecular weight of the acrylic rubber may be 450,000 or more and 900,000 or less.

[0018] The adhesive layer may have pressure-sensitive adhesiveness at 24° C. The temporary protective film may have a 5% weight loss temperature of 350° C. or higher.

[0019] The temporary protective film for semiconductor sealing molding may further include a cover film provided on the surface of the adhesive layer opposite to the surface on which the support film is provided.

[0020] In addition, one aspect of the present invention relates to a lead frame with a temporary protective film, which comprises: a lead frame having a chip pad and inner leads; and the above-mentioned temporary protective film for semiconductor sealing molding, the temporary protective film being adhered to the lead frame in a manner in which its adhesive layer is in single-sided contact with the lead frame.

[0021] In addition, one aspect of the present invention relates to a sealed molded body with a temporary protective film, comprising: a lead frame having a chip pad and inner leads; a semiconductor element mounted on the chip pad; a wire connecting the semiconductor element to the inner leads; a sealing layer that seals the semiconductor element and the wire; and the above-mentioned temporary protective film for semiconductor sealing molding, the adhesive layer of the temporary protective film being adhered to the surface of the lead frame on the opposite side of the surface of the semiconductor element mounted on the lead frame.

[0022] In addition, one aspect of the present invention relates to a method for manufacturing a semiconductor device, which comprises the following steps in sequence: a step of attaching the above-mentioned temporary protective film for semiconductor sealing molding to a single surface of the lead frame having a chip pad and inner leads in a direction in which its adhesive layer contacts the lead frame; a step of mounting a semiconductor element on the surface of the chip pad opposite to the temporary protective film; a step of providing a wire connecting the semiconductor element to the inner lead; a step of forming a sealing layer that seals the semiconductor element and the wire, thereby obtaining a sealed molding having a lead frame, a semiconductor element and a sealing layer; and a step of peeling the temporary protective film from the sealed molding.

[0023] When the lead frame has multiple chip pads and a semiconductor element is mounted on each of the multiple chip pads, the above-mentioned method for manufacturing a semiconductor device may further include the following step: before or after the temporary protective film is peeled off from the sealing molded body, the sealing molded body is divided to obtain a semiconductor device having one chip pad and a semiconductor element.

[0024] Effects of the Invention

[0025] According to the present invention, it is possible to provide a temporary protective film for semiconductor sealing molding which can be attached to a lead frame at room temperature and can be easily peeled off from the lead frame and sealing material after sealing molding while suppressing adhesive residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a cross-sectional view showing one embodiment of the temporary protective film.

[0027] Figure 2 This is a cross-sectional view showing one embodiment of the temporary protective film.

[0028] Figure 3 A cross-sectional view illustrating one embodiment of a method for manufacturing a semiconductor device.

[0029] Figure 4 It is a cross-sectional view showing one embodiment of a semiconductor device. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention are described in detail below. However, the present invention is not limited by the following embodiments. The upper limit and lower limit of the numerical range recorded in this specification can be combined arbitrarily. The numerical values ​​recorded in the embodiments can also be used as the upper limit or lower limit of the numerical range.

[0031] In this specification, "(meth)acrylic acid" means "acrylic acid" and "methacrylic acid".

[0032] <Temporary protective film>

[0033] Figure 1 This is a cross-sectional view showing a temporary protective film according to one embodiment. Figure 1 The temporary protective film 10 shown is composed of a support film 1 and an adhesive layer 2 provided on one surface of the support film 1. The adhesive layer may be formed on both surfaces of the support film 1. Figure 2 This is also a cross-sectional view showing a temporary protective film according to one embodiment. Figure 2 The temporary protective film 10' comprises a support film 1, an adhesive layer 2 provided on one main surface of the support film 1, and a substantially non-adhesive resin layer (non-adhesive layer 3) provided on the other main surface of the support film 1. These temporary protective films can be used as a temporary protective film for semiconductor sealing molding for temporary protection during the sealing molding of the lead frame by being attached to the back side (the side opposite to the side on which the semiconductor element is mounted) of the lead frame in the sealing molding process of forming a sealing layer for sealing the semiconductor element mounted on the lead frame.

[0034] <Adhesive layer>

[0035] The adhesive layer contains acrylic rubber. Generally, acrylic rubber is a copolymer containing (meth)acrylate as a monomer unit. For example, acrylic rubber is a copolymer obtained by polymerization reaction of a monomer mixture containing (meth)acrylate and other monomers such as (meth)acrylic acid, aromatic vinyl compounds, and cyanide vinyl compounds.

[0036] As the (meth) acrylic acid ester constituting the acrylic rubber, for example, butyl (meth) acrylate (for example, n-butyl (meth) acrylate), ethyl (meth) acrylate and methyl (meth) acrylate can be cited. (Meth) acrylate can also be compounds with reactive functional groups such as 2-hydroxyethyl (meth) acrylate and glycidyl (meth) acrylate. However, the acrylic rubber can also be a copolymer containing at least one (meth) acrylate selected from butyl (meth) acrylate, ethyl (meth) acrylate and methyl (meth) acrylate as the main component of the monomer unit. At this time, since there are few functional groups on the side chain of the acrylic rubber, the reaction with the adherend surface caused by heat treatment can be suppressed, and the peelability of the adhesive layer from the adherend becomes better. In addition, when using an acrylic rubber containing a monomer with a straight-chain hydrocarbon group as a monomer unit, there is a tendency that the wetting and spreading of the adhesive layer on the adherend becomes good. Here, "main component" refers to a monomer unit that accounts for more than 50% by mass relative to the total mass of the copolymer.

[0037] Examples of other monomers constituting the acrylic rubber include (meth)acrylic acid and acrylonitrile.

[0038] When the acrylic rubber contains at least one selected from (meth)acrylic acid and 2-hydroxyethyl (meth)acrylate as a monomer unit, the acrylic rubber may further have a carboxyl group and / or a hydroxyl group. The carboxyl group and / or hydroxyl group may be used for reaction with a release agent described below.

[0039] The glass transition temperature (Tg) of the acrylic rubber can be -50 to 40°C, -40°C to 30°C, or -30°C to 20°C from the viewpoint of maintaining the adhesiveness of the adhesive layer at room temperature. When the glass transition temperature of the acrylic rubber is above -50°C, the wettability decreases due to the heat treatment, so there is a tendency that the reduction in peelability is relatively suppressed. When the glass transition temperature of the acrylic rubber is below 20°C, there is a tendency that the reduction in adhesiveness at room temperature is relatively suppressed. Here, the glass transition temperature of the acrylic rubber is not particularly limited, and generally refers to a value measured by differential scanning calorimetry, differential thermal measurement, dynamic viscoelasticity measurement, or thermomechanical analysis.

[0040] The acrylic rubber may be a copolymer containing at least one monomer unit selected from butyl (meth)acrylate, ethyl (meth)acrylate and methyl (meth)acrylate as a main component, and the glass transition temperature of the acrylic rubber may be -30°C to 20°C. In this case, the wettability on the adherend is improved, and both the adhesiveness and the peeling properties can be achieved at particularly high levels.

[0041] The weight average molecular weight of the acrylic rubber may be 400,000 or more, 450,000 or more, or 700,000 or more from the viewpoint of low gas discharge and cohesive force maintenance. The weight average molecular weight of the acrylic rubber is not particularly limited and may be 900,000 or less. The weight average molecular weight of the acrylic rubber here refers to a value measured by gel permeation chromatography (converted value using standard polystyrene).

[0042] The acrylic rubber may also be used as a commercially available product. Commercially available products of the acrylic rubber include, for example, HTR-280DR (manufactured by Nagasechemtex Co., Ltd., with a weight average molecular weight of 800,000 to 900,000) and WS-023EK30 (manufactured by Nagasechemtex Co., Ltd., with a weight average molecular weight of 450,000 to 500,000). These acrylic rubbers may be used alone or in combination of two or more.

[0043] The content of the acrylic rubber in the adhesive layer may be 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more, and may be 100% by mass or less, based on the mass of the adhesive layer.

[0044] The adhesive layer containing acrylic rubber can have good adhesion at room temperature. In other words, the adhesive layer can have pressure-sensitive adhesiveness at, for example, 24°C without intentionally controlling the temperature. "Pressure-sensitive adhesiveness at 24°C" means that when the adhesive layer (40mm×160mm size) and the lead frame (50mm×157mm size) are pressed with a load of 20N under the condition of not intentionally controlling the temperature, for example, 24°C, the adhesive force of the adhesive layer to the lead frame is 5N / m or more. In addition, the adhesive force can be measured according to the method described in the examples described later.

[0045] The solid shear modulus of elasticity at 200°C of the temporary protective film (hereinafter also referred to as "solid shear modulus") is 5.0 MPa or more. The solid shear modulus of elasticity at 200°C of the temporary protective film may be 6 MPa or more, 8 MPa or more, or 10 MPa or more, and may be 25 MPa or less, or 20 MPa or less. By keeping the solid shear modulus of elasticity of the temporary protective film within these ranges, the residual glue on the lead frame and the sealing layer after sealing molding can be further suppressed.

[0046] The solid shear modulus here refers to the following value: a test piece having a temporary protective film of 5 mm × 8 mm size is mounted on a solid shear measurement fixture, and a dynamic viscoelasticity measuring device (e.g., Rheogel-E4000 manufactured by UBM Co., Ltd.) is used to measure the value under the conditions of a sine wave, 30 to 250°C, a heating rate of 5°C / min, and a frequency of 400 Hz. As the test piece, a laminate formed of a support film and an adhesive layer is used.

[0047] Here, in the manufacture of semiconductor devices, the wire bonding process is performed under conditions such as heating at 200 to 270°C for 3 to 60 minutes while using ultrasonic waves and pressing pressure. In the wire bonding process under such conditions, the adhesive layer becomes soft, so sometimes the wire cannot be accurately arranged. In addition, the exhaust gas generated by the thermal decomposition of the adhesive layer may contaminate the semiconductor element and the inner lead surface. When the solid shear elastic modulus of the temporary protective film is within the above range, these undesirable conditions in the wire bonding process can be further suppressed.

[0048] The thinner the thickness of the adhesive layer (film thickness), the higher the solid shear modulus. For example, in the case of an adhesive layer containing acrylic rubber, by adjusting the thickness within the range of 1 to 5 μm, the solid shear modulus of the temporary protective film at 200° C. can be easily made to be 5.0 MPa or more.

[0049] The thickness of the adhesive layer may be 5 μm or less or 3 μm or less from the viewpoint of suppressing or preventing defects during wire bonding (e.g., wire failure, wire breakage, insufficient wire bonding strength). From the same viewpoint, the thickness (film thickness) of the adhesive layer may be 1 μm or more, or 2 μm or more.

[0050] The adhesive layer may further contain a peeling agent. The peeling agent is a component that reduces the adhesive force of the adhesive layer to the lead frame and / or the sealing layer after seal molding, compared with a case where the adhesive layer does not contain the peeling agent.

[0051] As a stripping agent, an aliphatic compound can be used. An aliphatic compound refers to a compound having a straight-chain, branched or alicyclic hydrocarbon group. The aliphatic compound may have at least one functional group selected from an epoxy group and a hydroxyl group, and may also have an epoxy group. In other words, the stripping agent may be an aliphatic epoxy resin. In addition, the aliphatic compound may also be water-soluble. From the above viewpoints, the stripping agent may contain an aliphatic epoxy resin having a main chain having a hydrocarbon group with a carbon number of 2 or more that may have a side chain (branch) and an epoxy group bonded to the end of the main chain. Specifically, the stripping agent may contain at least one aliphatic compound (or aliphatic epoxy resin) selected from (poly)ethylene glycol diglycidyl ether, sorbitol polyglycidyl ether and glycerol polyglycidyl ether. These aliphatic compounds may be used alone or in combination of two or more. From the viewpoint of further suppressing residual glue, two or more may be used in combination.

[0052] When the acrylic rubber contains at least one selected from (meth)acrylic acid and 2-hydroxyethyl acrylate as a monomer unit and an aliphatic compound having an epoxy group is used as a releasability imparting agent, the releasability from the lead frame and the sealing layer becomes better, and the washing treatment when the adhesive layer remains on the lead frame and the sealing layer becomes more efficient. It is presumed that the reason for this is that the epoxy group of the releasability imparting agent reacts with the hydroxyl group and / or carboxyl group of the side chain of the acrylic rubber, and the washing property is increased due to the releasability imparting agent being a low molecular weight body and having solubility compared to the acrylic rubber.

[0053] The content of the peeling agent can be 6 parts by mass or more, or 10 parts by mass or more relative to 100 parts by mass of acrylic rubber, and can be less than 60 parts by mass, less than 50 parts by mass, or less than 30 parts by mass. When the content of the peeling agent is less than 60 parts by mass, there is a tendency to suppress the reduction of the adhesion between the adhesive layer and the support film, and the adhesive layer becomes difficult to peel off. When the content of the peeling agent is 6 parts by mass or more, there is a tendency to become easier to ensure sufficient peelability and washability.

[0054] The adhesive layer may further contain other components as necessary. Examples of other components include aminoalkyd resins and fatty acids.

[0055] The adhesive strength of the adhesive layer to the lead frame and the sealing layer after sealing can be 450 N / m or less, or 300 N / m or less. The adhesive strength to the lead frame and the sealing layer after sealing can be measured by the method described in the examples below.

[0056] The 5% weight loss temperature of the temporary protective film may be 350°C or higher. As a result, the amount of outgassing is reduced and the wire bonding property becomes better. The 5% weight loss temperature of the temporary protective film may be 500°C or lower, or 450°C or lower. The 5% weight loss temperature may be measured using a differential thermobalance (e.g., Seiko Instruments Co., Ltd., SSC5200 model) at a heating rate of 10°C / min and in an air atmosphere.

[0057] <Support film>

[0058] The support film is not particularly limited and may be a heat-resistant resin film. When a heat-resistant resin film is used as the support film, the support film will not soften even under high temperature conditions (e.g., above 200° C.), and the operability becomes more excellent. Specifically, from the viewpoint of improving heat resistance, the glass transition temperature (Tg) of the support film may be above 200° C. or above 250° C.

[0059] Examples of the heat-resistant resin constituting the support film include aromatic polyimide, aromatic polyamide, aromatic polyamideimide, aromatic polysulfone, aromatic polyethersulfone, polyphenylene sulfide, aromatic polyetherketone, polyarylate, aromatic polyetheretherketone, polyethylene naphthalate, and polyethylene terephthalate.

[0060] Support film can be polyimide film from the aspect of having heat resistance and can further improve the closeness to adhesive layer.When using polyimide film as support film, polyimide film can also be processed by high closeness such as plasma treatment, corona treatment, primer treatment.When support film is relatively low to the closeness of adhesive layer, when temporary protective film is peeled off from lead frame and sealing layer, peeling can be sent out at the interface of adhesive layer and support film, and adhesive layer is easy to remain in lead frame and sealing layer one side.Thus, support film is preferably high fully to the closeness of adhesive layer.

[0061] The thickness (film thickness) of the support film is not particularly limited, and may be 100 μm or less, 50 μm or less, or 25 μm or less from the viewpoint of reducing residual stress related to warping of the lead frame after the temporary protective film is attached to the lead frame. The thickness of the support film may be 5 μm or more or 10 μm or more.

[0062] In the temporary protective film of one embodiment, the thickness of the support film may be 5 μm or more and 50 μm or less, and the thickness of the adhesive layer may be 1 μm or more and 5 μm or less.

[0063] <Cover film>

[0064] The temporary protective film for semiconductor sealing molding may also include a covering film provided on the surface of the adhesive layer opposite to the surface provided with the support film. That is, the temporary protective film for semiconductor sealing molding may also be a temporary protective film for semiconductor sealing molding with a covering film. The covering film is not particularly limited and may be a polyethylene terephthalate film or a polyethylene terephthalate film provided with a release layer.

[0065] The thickness of the cover film may be greater than or equal to 10 μm and less than or equal to 100 μm, or greater than or equal to 20 μm and less than or equal to 100 μm.

[0066] Figure 2 The non-adhesive layer 3 of the temporary protective film 10' of the embodiment is a resin layer that has substantially no adhesion (or pressure-sensitive adhesion) to the lead frame at 0 to 270°C. For example, a resin layer with a high glass transition temperature can function as a non-adhesive layer. Specifically, the non-adhesive layer can be, for example, a resin layer containing polyamide-imide. The thickness of the non-adhesive layer is not particularly limited, and can be, for example, 1 to 10 μm.

[0067] <Method for producing temporary protective film>

[0068] The temporary protective film of one embodiment can be manufactured by the following method, for example. First, acrylic rubber is mixed with solvents such as cyclohexanone and methyl ethyl ketone and other components such as a peeling agent used as needed to prepare a varnish. After the prepared varnish is applied to one side of a support film, the solvent is removed from the coating by heat treatment to form an adhesive layer on the support film. Thus, a temporary protective film with a two-layer structure can be obtained.

[0069] The method for coating the varnish on one side of the support film is not particularly limited, and examples thereof include roll coating, reverse roll coating, gravure coating, bar coating, comma coating, die coating, and reduced pressure die coating.

[0070] <Method for manufacturing semiconductor device>

[0071] A semiconductor device can be manufactured by a method of a sealing molding process of a semiconductor element using a temporary protective film of an embodiment. The manufactured semiconductor device can, for example, have a lead frame and a semiconductor element carried thereon, and a sealing layer that seals the semiconductor element on one side of the semiconductor element of the lead frame, and a Non Lead Type Package (leadless package) in which the back of the lead frame is exposed for external connection. As specific examples thereof, QFN (Quad Flat Non-leaded Package) and SON (Small Outline Non-leaded Package) can be cited.

[0072] Figure 3 It is a cross-sectional view showing a method for manufacturing a semiconductor device according to an embodiment. Figure 4 Yes means through Figure 3 The following is a cross-sectional view of one embodiment of a semiconductor device obtained by a manufacturing method of the present invention. Each step will be described below with reference to each drawing as needed.

[0073] Figure 3The manufacturing method of the semiconductor device of the embodiment comprises the following steps in sequence: a step of pasting the temporary protective film 10 on a single side (back side) of the lead frame 11 having a chip pad 11a and an inner lead 11b in a direction in which the adhesive layer thereof contacts the lead frame; a step of mounting (bonding) the semiconductor element 14 on the surface of the chip pad 11a opposite to the temporary protective film 10; a step of providing the wire 12 connecting the semiconductor element 14 to the inner lead 11b; a step of forming the sealing layer 13 sealing the semiconductor element 14 and the wire 12 and obtaining the sealing molded body 20 having the lead frame 11, the semiconductor element 14 and the sealing layer 13; and a step of peeling the temporary protective film 10 from the sealing molded body 20.

[0074] The temporary protective film 10 can be attached to the lead frame 11 at room temperature (eg, 5 to 35° C.). The method of attachment is not particularly limited, and for example, roll lamination may be used.

[0075] The lead frame with temporary protective film according to one embodiment includes a lead frame 11 having a die pad 11a and inner leads 11b, and a temporary protective film 10 attached to the lead frame 11 such that an adhesive layer 2 thereof contacts one surface of the lead frame 11.

[0076] The material of the lead frame 11 is not particularly limited, and may be, for example, an iron alloy such as 42 alloy, copper, or a copper alloy. When a lead frame of copper or a copper alloy is used, the surface of the lead frame may be coated with palladium, gold, silver, or the like. In order to improve the adhesion with the sealing material, the surface of the lead frame may be physically roughened. The surface of the lead frame may also be subjected to chemical treatment such as resin bleed out (EBO) prevention treatment to prevent the silver paste from seeping out.

[0077] The semiconductor element 14 is usually mounted (bonded) on the die pad 11a by an adhesive (eg, silver paste). The adhesive may be cured by heat treatment (eg, 140 to 200°C, 30 minutes to 2 hours).

[0078] The wire 12 is not particularly limited, and may be, for example, a gold wire, a copper wire, or a palladium-coated copper wire. For example, the semiconductor element and the inner lead may be bonded to the wire 12 by heating at 200 to 270° C. for 3 to 60 minutes and by using ultrasonic waves and pressing pressure.

[0079] After wire bonding using the wire 12 and before the sealing molding process of obtaining the sealing molding 20 (forming the sealing layer 13), the lead frame 11 may also be subjected to plasma treatment. By plasma treatment, the closeness between the sealing layer and the lead frame can be further improved, and the reliability of the semiconductor device can be further improved. As a plasma treatment, for example, a method of injecting argon, nitrogen, oxygen and other gases at a prescribed gas flow rate under reduced pressure conditions (for example, below 9.33 Pa) and performing plasma irradiation can be cited. The irradiation output power of the plasma in the plasma treatment can be, for example, 10 to 500 W. In addition, the time of the plasma treatment can be, for example, 5 to 50 seconds. The gas flow rate in the plasma treatment can be 5 to 50 sccm.

[0080] In the process of sealing and molding, a sealing material is used to form a sealing layer 13. Through sealing and molding, a sealing molded body 20 having a plurality of semiconductor elements 14 and the sealing layer 13 that seals them together is obtained. During the sealing and molding, since the temporary protective film 10 is provided, it is possible to prevent the sealing material from being wound around the back side of the lead frame 11.

[0081] A sealed molded body with a temporary protective film in one embodiment comprises a lead frame 11 having a chip pad 11a and an inner lead 11b, a semiconductor element 14 mounted on the chip pad 11a, a wire 12 connecting the semiconductor element 14 to the inner lead 11b, a sealing layer 13 that seals the semiconductor element 14 and the wire 12, and a temporary protective film 10, wherein an adhesive layer 2 of the temporary protective film 10 is adhered to a surface of the lead frame 11 opposite to a surface on which the semiconductor element 14 is mounted.

[0082] The temperature during the formation of the sealing layer (sealing temperature) may be 140 to 200° C., or 160 to 180° C. The pressure during the formation of the sealing layer (sealing pressure) may be 6 to 15 MPa, or 7 to 10 MPa. The heating time for sealing molding (sealing time) may be 1 to 5 minutes, or 2 to 3 minutes.

[0083] The formed sealing layer 13 may be heated and cured as required. The heating temperature for curing the sealing layer (sealing curing temperature) may be 150 to 200° C., or 160 to 180° C. The heating time for curing the sealing layer (sealing curing time) may be 4 to 7 hours, or 5 to 6 hours.

[0084] The material of the sealing material is not particularly limited, and examples thereof include epoxy resins such as cresol novolac epoxy resin, phenol novolac epoxy resin, biphenyl diepoxy resin, and naphthol novolac epoxy resin. The sealing material may contain fillers, flame retardants such as bromine compounds, and additives such as wax components.

[0085] After forming the sealing layer 13 (sealing molding), the temporary protective film 10 is peeled off from the lead frame 11 and the sealing layer 13 of the obtained sealing molded body 20. When the sealing layer is cured, the temporary protective film 10 can be peeled off at any time point before or after the curing of the sealing layer.

[0086] The temperature when peeling off the temporary protective film is not particularly limited and can be room temperature (e.g., 5 to 35°C). The temperature can also be above the glass transition temperature of the adhesive layer. At this time, the temporary protective film has better peelability to the lead frame and the sealing material. When the Tg of the acrylic rubber in the adhesive layer is, for example, below 5°C or below 0°C, the Tg of the adhesive layer becomes equal to or below room temperature, and it is easy to obtain good peelability at room temperature.

[0087] The method for manufacturing a semiconductor device may further include, as needed, a step of removing the adhesive layer (residual glue) remaining on the lead frame 11 and the sealing layer 13 after the stripping step. At this time, for example, a solvent may be used to remove the remaining adhesive layer. As a solvent, for example, dimethyl sulfoxide, ethylene glycol, and water may be used. The solvent may be used alone or in combination of two or more. A surfactant may also be added to the solvent. When the solvent contains water, the solvent may be a solution adjusted to alkaline (alkaline solution). The pH of the alkaline solution may be greater than 10 or greater than 12. While removing with a solvent, mechanical scrubbing may also be performed as needed. In addition, the burrs and oxide film of the sealing layer may also be removed.

[0088] When the lead frame includes a plurality of patterns having chip pads and inner leads, the sealing molded body 20 can be divided as needed to obtain a plurality of lead frames each having one semiconductor element. Figure 4 A semiconductor device 100 is provided.

[0089] That is, when the lead frame 11 has multiple chip pads 11a and a semiconductor element 14 is mounted on each of the multiple chip pads 11a, a manufacturing method of one embodiment may further include a step of dividing the sealing molded body 20 before or after peeling the temporary protective film 10 from the sealing molded body 20 to obtain a semiconductor device 100 having one chip pad 11a and a semiconductor element 14.

[0090] The semiconductor device manufactured using the temporary protective film of one embodiment is excellent in terms of high density, small area, and thinness, and can be preferably used in electronic devices such as mobile phones, smartphones, notebook computers, and tablet computers.

[0091] Example

[0092] The present invention is further specifically described below by way of examples, but the present invention is not limited to the following examples.

[0093] <Manufacturing of Temporary Protective Films of Examples 1 to 15 and Comparative Examples 1 to 4>

[0094] (Production of varnish for finishing)

[0095] Cyclohexanone as a solvent was added to a resin composition having a composition (unit: parts by mass) shown in Table 1 or Table 2, and stirred and mixed to obtain varnishes A to O having a nonvolatile content of 12% by mass. Details of the acrylic rubber and the releasability-imparting agent shown in the table are as follows.

[0096] Acrylic rubber

[0097] Acrylic rubber Ai (manufactured by Nagase Chemtex Co., Ltd., trade name: WS-023EK30, weight average molecular weight: 500,000)

[0098] Acrylic rubber Aii (manufactured by Nagase Chemtex Co., Ltd., trade name: HTR-280DR, weight average molecular weight: 900,000)

[0099] ·Releasability-imparting agent Bi (manufactured by Nagase Chemtex Co., Ltd., trade name: EX-614B, sorbitan polyglycidyl ether, epoxy equivalent: 174)

[0100] ·Releasability-imparting agent Bii (manufactured by Nagase Chemtex Co., Ltd., trade name: EX-810, ethylene glycol diglycidyl ether, epoxy equivalent: 113)

[0101] [Table 1]

[0102]

[0103] [Table 2]

[0104]

[0105] (Preparation of temporary protective film)

[0106] Examples 1 to 13

[0107] The obtained varnishes A to M were coated on a support film (polyimide film, manufactured by Ube Industries, Ltd., trade name: UPILEX25SGA, film thickness: 25 μm). The coating film was heated at 90°C for 2 minutes and at 150°C for 2 minutes to dry, and an adhesive layer with a thickness of 2 μm was formed on the support film to obtain temporary protective films of Examples 1 to 13. For each temporary protective film of Examples 1 to 13, the solid shear elastic modulus at 200°C was measured by the following method. The results are shown in Table 3.

[0108] Determination method of shear elastic modulus of solid

[0109] The test piece obtained by cutting the temporary protective film into a size of 5 mm × 8 mm was installed in a solid shear measurement fixture, and the solid shear elastic modulus was measured under the conditions of sine wave, 30 to 250°C, a heating rate of 5°C / min, and a frequency of 400Hz using a dynamic viscoelasticity measuring device (UBM Co., Ltd.). In addition, the input thickness was fixed at 0.1 mm, and the deformation was controlled to 1.95 μm and 1.95%. The solid shear elastic modulus at 200°C was read from the measurement results.

[0110] Embodiment 14

[0111] A temporary protective film of Example 14 was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer was 1 μm. The solid shear elastic modulus of the temporary protective film at 200° C. was 8.2 MPa.

[0112] Embodiment 15

[0113] A temporary protective film of Example 15 was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer was 5 μm. The solid shear elastic modulus of the temporary protective film at 200° C. was 5.7 MPa.

[0114] Comparative Example 1

[0115] A temporary protective film of Comparative Example 1 was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer was 6 μm. The solid shear elastic modulus of the temporary protective film at 200° C. was 4.0 MPa.

[0116] Comparative Example 2

[0117] A temporary protective film of Comparative Example 2 was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer was 8 μm. The solid shear elastic modulus of the temporary protective film at 200° C. was 3.1 MPa.

[0118] Comparative Example 3

[0119] A temporary protective film of Comparative Example 3 was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer was 10 μm. The solid shear elastic modulus of the temporary protective film at 200° C. was 1.8 MPa.

[0120] Comparative Example 4

[0121] Varnish O was applied on a support film (manufactured by DU PONT-TORAY Co., Ltd., trade name: Kapton 100EN, film thickness: 25 μm). The coating film was heated at 90° C. for 2 minutes and at 150° C. for 2 minutes to dry, and a 5 μm thick adhesive layer was formed on the support film to obtain a temporary protective film of Comparative Example 4. The solid shear elastic modulus of the temporary protective film at 200° C. was 3.2 MPa.

[0122] <Production of Temporary Protective Film of Comparative Example 5>

[0123] (Production of varnish for finishing)

[0124] In a 5-liter four-necked flask equipped with a thermometer, a stirrer, a nitrogen inlet tube and a fractionating tower, 270.9 g (0.66 mole) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane and 8.7 g (0.035 mole) of 1,3-bis(3-aminopropyl)-tetramethyldisiloxane were added under a nitrogen atmosphere and dissolved in 1950 g of N-methyl-2-pyrrolidone. The solution was then cooled to 0°C, and 149.5 g (0.71 mole) of trimellitic anhydride chloride was added at this temperature. After the trimellitic anhydride chloride was dissolved, 100 g of triethylamine was added. After continuous stirring at room temperature for 2 hours, the temperature was raised to 180°C, and imidization was completed through 5 hours of reaction. The reaction solution was put into methanol to separate the polymer. After drying, it was dissolved in N-methyl-2-pyrrolidone, put into methanol, and the polymer was separated again. The separated polymer was dried under reduced pressure to obtain a purified powdery polyetheramideimide. 120 g of the polyetheramideimide and 3.6 g of a silane coupling agent (manufactured by Dow Corning Toray Co., Ltd., trade name: SH6040) were dissolved in 360 g of N-methyl-2-pyrrolidone to obtain a varnish P for forming an adhesive layer.

[0125] In a 5-liter four-necked flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a fractionating tower, 172.4 g (0.42 mole) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane and 153.7 g (0.42 mole) of 4,4'-methylenebis(2,6-diisopropylaniline) were added under a nitrogen atmosphere, and they were dissolved in 1550 g of N-methyl-2-pyrrolidone. The solution was then cooled to 0°C, and 174.7 g (0.83 mole) of trimellitic anhydride chloride was added at this temperature. After the trimellitic anhydride chloride was dissolved, 130 g of triethylamine was added. After continuous stirring at room temperature for 2 hours, the temperature was raised to 180°C, and imidization was completed through 5 hours of reaction. The reaction solution was put into methanol to separate the polymer. After drying, it was dissolved in N-methyl-2-pyrrolidone, put into methanol, and the polymer was separated again. The separated polymer was dried under reduced pressure to obtain a purified powdered polyetheramideimide. 120 g of the polyetheramideimide and 6 g of a silane coupling agent (manufactured by Dow Corning Toray Co., Ltd., trade name: SH6040) were dissolved in 360 g of N-methyl-2-pyrrolidone to obtain a varnish Q for forming a non-adhesive layer.

[0126] (Preparation of temporary protective film)

[0127] Varnish P was applied on a support film (polyimide film, manufactured by Ube Industries, Ltd., trade name: UPILEX25SGA, film thickness: 25 μm), and dried by heating at 100° C. for 10 minutes and at 300° C. for 10 minutes to form an adhesive layer with a film thickness of 8 μm. Next, varnish Q was applied on the back of the support film after the adhesive varnish was applied, and dried by heating at 100° C. for 10 minutes and at 300° C. for 10 minutes to obtain a non-adhesive layer with a film thickness of 6 μm. Thus, a temporary protective film of Comparative Example 5 having an adhesive layer and a non-adhesive layer was obtained. The solid shear elastic modulus of the temporary protective film was 21.0 MPa.

[0128] <Evaluation>

[0129] (Adhesion strength of adhesive layer)

[0130] (1) After pasting at room temperature (adhesion at room temperature)

[0131] As the lead frame, a CDA194 frame (Cu, manufactured by Shinko Electric Industries, Ltd.) and a CDA194 palladium-plated frame (PPF, manufactured by Shinko Electric Industries, Ltd.) were prepared. Using a hand roller, each temporary protective film of the embodiment and the comparative example was pasted on these lead frames (50mm×157mm size) at room temperature (24°C) and a load of 20N in a direction in which the adhesive layer (40mm×160mm size) was in contact with the lead frame. Afterwards, a dynamometer was used to peel off each temporary protective film at a speed of 50mm / min in the 180° direction, and the maximum load at this time was recorded as the adhesive force. Thus, the adhesion (pressure-sensitive adhesion) of each temporary protective film at room temperature was evaluated.

[0132] However, in the case of the temporary protective film of Comparative Example 5, since the adhesive layer has weak adhesion at room temperature, a press machine heated to 230° C. was used to apply a pressure of 6 MPa to the tape and pressurized for 10 seconds to adhere the adhesive layer to the lead frame (the same applies to the following adhesion measurement).

[0133] (2) After heating treatment (evaluation of peelability after heating treatment)

[0134] As the lead frame, a CDA194 frame (Cu, manufactured by Shinko Electric Industries, Ltd.) and a CDA194 palladium-plated frame (PPF, manufactured by Shinko Electric Industries, Ltd.) were prepared. Using a hand roller, each temporary protective film of the embodiment and the comparative example was pasted on these lead frames (50mm×157mm size) in the direction in which the adhesive layer (40mm×160mm size) was in contact with the lead frame, at room temperature (24°C) and under a load of 20N. Afterwards, the lead frame and the temporary protective film were heated in an oven under an air atmosphere while changing the conditions in the order of 180°C for 60 minutes, 200°C for 60 minutes, and 175°C for 2 minutes. Afterwards, each temporary protective film was peeled off at a speed of 50mm / min in the 180° direction using a dynamometer, and the maximum load at this time was recorded as the adhesive force. Thus, the peelability of each temporary protective film from the lead frame after heat treatment under conditions equivalent to sealing molding was evaluated.

[0135] (3) After seal molding (evaluation of peelability after seal molding)

[0136] As a lead frame, a CDA194 frame (Cu, manufactured by Shinko Electric Industry Co., Ltd.) was prepared. Using a hand roller, each temporary protective film of the embodiment and the comparative example was pasted on the lead frame (50 mm × 157 mm size) at room temperature (24°C) and a load of 20N in a direction in which the adhesive layer (40 mm × 160 mm size) was in contact with the lead frame. Thereafter, the lead frame and the temporary protective film were heated in an oven under an air atmosphere while changing the conditions in the order of 180°C for 60 minutes and 200°C for 60 minutes.

[0137] Next, plasma treatment was performed on the surface of the lead frame opposite to the temporary protective film under the conditions of argon atmosphere (flow rate: 20 sccm), 150 W, and 15 seconds. After that, sealing was performed using a molding machine (manufactured by Apicyamada Co., Ltd.) under the conditions of 175° C., 6.8 MPa, and 2 minutes, and a sealing layer was formed on the surface of the lead frame opposite to the temporary protective film using a sealing material (trade name: GE-7470L-A, manufactured by Hitachi Chemical Co., Ltd.).

[0138] Afterwards, each temporary protective film was peeled off at a speed of 50 mm / min in a 180° direction using a dynamometer, and the maximum load when the adhesive layer was peeled off from the sealing layer was recorded as the adhesive force to the sealing layer after the sealing was formed. Thus, the peelability of each temporary protective film from the sealing layer after the sealing was formed was evaluated.

[0139] (4) After the sealant layer is cured (evaluation of peelability after the sealant layer is cured)

[0140] As the lead frame, a CDA194 frame (Cu, manufactured by Shinko Electric Industries, Ltd.) and a CDA194 palladium-plated frame (PPF, manufactured by Shinko Electric Industries, Ltd.) were prepared. Using a hand roller, each temporary protective film of the embodiment and the comparative example was pasted on these lead frames (50mm×157mm size) at room temperature (24°C) and a load of 20N in a direction in which the adhesive layer (40mm×160mm size) was in contact with the lead frame. Afterwards, the lead frame and the temporary protective film were heated in an oven under an air environment while changing the conditions in the order of 180°C for 60 minutes and 200°C for 60 minutes. Plasma treatment was performed on the surface of the lead frame on the opposite side of the temporary protective film under an argon environment (flow rate: 20sccm), 150W, and 15 seconds. Next, a molding machine (manufactured by Apicyamada Co., Ltd.) was used to perform sealing molding at 175°C, 6.8MPa, and 2 minutes, and a sealing layer was formed on the surface of the lead frame on the opposite side of the temporary protective film using a sealing material (trade name: GE-7470L-A, manufactured by Hitachi Chemical Co., Ltd.). Furthermore, the sealing layer was cured by heating at 180°C for 5 hours in an oven under an air environment. After heating, each temporary protective film was peeled off at a speed of 50mm / min using a dynamometer in a 180° direction, and the maximum load when the adhesive layer was peeled off from the lead frame or the sealing layer was recorded as the adhesive force to the lead frame or the sealing layer after the sealing molding. Thus, the peelability of the sealing layer of each temporary protective film after curing was evaluated.

[0141] (5) Residual glue

[0142] The temporary protective films of the embodiment and the comparative example were attached to a CDA194 frame (Cu, manufactured by Shinko Electric Co., Ltd.) at room temperature (24°C) and a load of 20 N, with the adhesive layer in contact with the lead frame. The lead frame and the temporary protective film were heated in an oven under an air atmosphere, with the conditions being changed in the order of 180°C for 60 minutes and 200°C for 60 minutes. Plasma treatment was performed on the surface of the lead frame on the opposite side of the temporary protective film under an argon atmosphere (flow rate: 20 sccm), 150 W, and 15 seconds.

[0143] A sealing layer was formed on the surface of the lead frame opposite to the temporary protective film using a sealing material (trade name: GE-7470L-A, manufactured by Hitachi Chemical Co., Ltd.) by sealing molding at 175°C, 6.8 MPa, and 2 minutes.

[0144] After that, each temporary protective film was peeled off at a speed of 50 mm / min in the 180° direction, and the state of the residual adhesive on the sealing layer and the lead frame after peeling was checked. The residual adhesive was evaluated in 6 levels according to the following criteria based on the ratio of the area of ​​the residual adhesive portion to the total area of ​​the surface of the sealing layer and the lead frame.

[0145] 5: 60-100% (the remaining adhesive layer is thicker overall)

[0146] 4: 60-100% (the remaining adhesive layer is generally thin)

[0147] 3: 30% or more and less than 60%

[0148] 2: 10% or more and less than 30%

[0149] 1: More than 0% and less than 10%

[0150] 0:0%

[0151] (6) 5% weight reduction temperature

[0152] The 5% weight reduction temperature of each temporary protective film of Examples and Comparative Examples was measured using a differential thermobalance (SSC5200, manufactured by Seiko Instruments) at a temperature increase rate of 10° C. / min in an air atmosphere.

[0153] The above evaluation results are shown in Tables 3 and 4. The temporary protective film of each example can be attached to the lead frame at room temperature, and can be easily peeled off from the lead frame and the sealing layer after sealing and molding with little residual adhesive.

[0154] [Table 3]

[0155]

[0156] [Table 4]

[0157]

[0158] Explanation of symbols

[0159] 1 support film, 2 adhesive layer, 3 non-adhesive layer, 10, 10' temporary protective film, 11 lead frame, 11a die pad, 11b inner lead, 12 wire, 13 sealing layer, 14 semiconductor element, 20 sealing molded body, 100 semiconductor device.

Claims

1. A temporary protective film for semiconductor sealing molding, comprising a support film and an adhesive layer provided on the support film, The temporary protective film has a solid shear elastic modulus at 200° C. of 5.0 MPa or more and 20 MPa or less, The adhesive layer is composed of acrylic rubber, or contains acrylic rubber and a releasability imparting agent. The release agent contains an aliphatic epoxy resin having a hydrocarbon group and an epoxy group, wherein the hydrocarbon group has a main chain having 2 or more carbon atoms which may have a side chain, and the epoxy group is bonded to the end of the main chain, and the content of the release agent is 5 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the acrylic rubber. The adhesive layer has a thickness of 1 μm or more and 5 μm or less.

2. The temporary protective film for semiconductor sealing molding according to claim 1, wherein The adhesive layer contains the releasability-imparting agent.

3. The temporary protective film for semiconductor sealing molding according to claim 2, wherein: The content of the releasability-imparting agent is 6 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the acrylic rubber.

4. The temporary protective film for semiconductor sealing molding according to any one of claims 1 to 3, wherein The adhesive layer has a thickness of 2 μm or more and 5 μm or less.

5. The temporary protective film for semiconductor sealing molding according to any one of claims 1 to 3, wherein The supporting film is a polyimide film.

6. The temporary protective film for semiconductor sealing molding according to any one of claims 1 to 3, wherein The acrylic rubber is a copolymer containing at least one monomer unit selected from butyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, (meth)acrylic acid, acrylonitrile, 2-hydroxyethyl (meth)acrylate and glycidyl (meth)acrylate.

7. The temporary protective film for semiconductor sealing molding according to any one of claims 1 to 3, wherein The weight average molecular weight of the acrylic rubber is 450,000 or more and 900,000 or less.

8. The temporary protective film for semiconductor sealing molding according to any one of claims 1 to 3, wherein The adhesive layer has pressure-sensitive adhesiveness at 24°C.

9. The temporary protective film for semiconductor sealing molding according to any one of claims 1 to 3, wherein The temporary protective film has a 5% weight loss temperature of 350° C. or higher. 10 . The temporary protective film for semiconductor sealing molding according to claim 1 , further comprising a cover film provided on a surface of the adhesive layer opposite to a surface on which the support film is provided.

11. A lead frame with a temporary protective film, comprising: A lead frame having a chip pad and inner leads; and The temporary protective film for semiconductor sealing molding according to any one of claims 1 to 10, The temporary protection film is attached to the lead frame in such a manner that the adhesive layer thereof contacts one surface of the lead frame.

12. A sealed molded body with a temporary protective film, comprising: A lead frame having a chip pad and inner leads; a semiconductor element mounted on the chip pad; A wire connecting the semiconductor element to the inner lead; A sealing layer for sealing the semiconductor element and the wire; and The temporary protective film for semiconductor sealing molding according to any one of claims 1 to 10, The adhesive layer of the temporary protective film is attached to a surface of the lead frame opposite to a surface on which the semiconductor element is mounted.

13. A method for manufacturing a semiconductor device, comprising the following steps in sequence: A step of attaching the temporary protective film for semiconductor sealing molding according to any one of claims 1 to 10 to one surface of the lead frame having a die pad and inner leads in a direction in which the adhesive layer thereof contacts the lead frame; a step of mounting a semiconductor element on a surface of the die pad opposite to the temporary protective film; The step of providing a wire connecting the semiconductor element to the inner lead; A step of forming a sealing layer for sealing the semiconductor element and the wire to obtain a sealed molded body having the lead frame, the semiconductor element and the sealing layer; as well as a step of peeling the temporary protective film from the sealed molded body.

14. The method according to claim 13, wherein: The lead frame has a plurality of die pads, and the semiconductor element is mounted on each of the plurality of die pads. The method further comprises the step of dividing the sealed molded body before or after the temporary protective film is peeled off from the sealed molded body to obtain a semiconductor device having one of the die pads and the semiconductor element.

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