Temporary protective film for semiconductor device manufacturing and method for manufacturing semiconductor device

Abstract

To provide a temporary protective film that can suppress residual on a lead frame at the time of peeling.SOLUTION: A temporary protective film for a semiconductor device manufacturing has a support film and an adhesion layer provided on the support film, and the adhesion layer contains acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a temporary protective film for use in manufacturing a semiconductor device and a method for manufacturing a semiconductor device. [Background technology]

[0002] In semiconductor packages, a structure is sometimes adopted in which an encapsulating layer is formed only on the semiconductor element side of the lead frame, and the back surface of the lead frame is exposed. In manufacturing a semiconductor package having this structure, there is a risk that the encapsulating material will get around to the back surface of the lead frame when the encapsulating layer is formed. To prevent this, a method is known in which a temporary protective film is attached to the back surface of the lead frame (Patent Document 1). The temporary protective film is peeled off from the lead frame after the encapsulating layer is formed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2001 / 035460 Summary of the Invention [Problem to be solved by the invention]

[0004] In the temporary protective film, it is desirable that the adhesive component of the temporary protective film does not remain on the lead frame when the temporary protective film is peeled off from the lead frame after the sealing layer is formed. Therefore, one aspect of the present invention aims to provide a temporary protective film that can suppress the adhesive component from remaining on the lead frame when peeled off. [Means for solving the problem]

[0005] According to the inventors' research, it has been found that by setting the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the acrylic polymer contained in the adhesive layer of the temporary protective film to a specific range, the occurrence of residues on the lead frame can be suppressed compared to the case of using an acrylic polymer having an Mw and Mw / Mn outside the specific range.

[0006] The present invention includes the following aspects. [1] A temporary protective film for use in the manufacture of semiconductor device, comprising a support film and an adhesive layer provided on the support film, the adhesive layer containing an acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less. [2] The temporary protective film according to [1], wherein the acrylic polymer contains alkyl (meth)acrylate and (meth)acryloylmorpholine as monomer units. [3] The temporary protective film according to [1] or [2], wherein the weight average molecular weight of the acrylic polymer is 850,000 or more. [4] A method for manufacturing a semiconductor device comprising the steps of attaching a temporary protective film to one side of a substrate, mounting a semiconductor element on the side of the substrate opposite the temporary protective film, encapsulating the semiconductor element, and peeling the temporary protective film from the substrate, in that order, wherein the temporary protective film comprises a support film and an adhesive layer provided on the support film, and the adhesive layer contains an acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less. [5] The method according to [4], wherein the acrylic polymer contains alkyl (meth)acrylate and (meth)acryloylmorpholine as monomer units. [6] The method according to [4] or [5], wherein the weight average molecular weight of the acrylic polymer is 850,000 or more. Effect of the Invention

[0007] According to one aspect of the present invention, it is possible to provide a temporary protective film that can be prevented from remaining on a lead frame when peeled off. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view showing one embodiment of a temporary protective film. [Diagram 2] 1A to 1C are cross-sectional views illustrating an embodiment of a method for manufacturing a semiconductor device. [Diagram 3] 1A to 1C are cross-sectional views illustrating an embodiment of a method for manufacturing a semiconductor device. [Figure 4] 1 is a cross-sectional view showing an embodiment of a semiconductor device. [Diagram 5] FIG. 2 is a perspective view showing one embodiment of a reel body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a temporary protective film according to one embodiment. As shown in FIG. 1, the temporary protective film 10 according to one embodiment includes a support film 1 and an adhesive layer 2 provided on the support film 1. The temporary protective film 10 can be used as a temporary protective film for manufacturing a semiconductor device. More specifically, the temporary protective film 10 can be used as a temporary protective film for semiconductor encapsulation molding for temporarily protecting the lead frame during encapsulation molding by attaching it to the back surface of the lead frame (the surface opposite to the surface on which the semiconductor element is mounted) in the process of encapsulation molding to form an encapsulation layer that encapsulates the semiconductor element mounted on the die pad of the lead frame.

[0010] The support film 1 may be, for example, a film of at least one polymer selected from the group consisting of polyimide, polyamide, polyamideimide, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherketone, polyarylate, polyetheretherketone, and polyethylene naphthalate, and may be preferably a polyimide film. The polyimide may be an aromatic polyimide. The support film 1 may be a film of copper, aluminum, stainless steel, or nickel. When the support film 1 is a polymer film, its surface may be surface-treated by a method such as a chemical treatment, an alkali treatment, a silane coupling treatment, or the like, a physical treatment, such as a sand mat treatment, a plasma treatment, or a corona treatment.

[0011] The thickness of the support film 1 may be, for example, 5 μm or more, and 100 μm or less, or 50 μm or less. The ratio T2 / T1 of the thickness T2 of the adhesive layer 2 to the thickness T1 of the support film 1 may be 0.1 or more, and may be 0.5 or less, 0.3 or less, or 0.2 or less.

[0012] The adhesive layer 2 contains an acrylic polymer having a weight average molecular weight (Mw) of 550,000 or more and a molecular weight distribution (Mw / Mn) of 2.0 or less.

[0013] The Mw of the acrylic polymer may be 600,000 or more, and from the viewpoint of suppressing the adhesive component from remaining on the sealing layer after the temporary protective film is peeled off from the lead frame and the sealing layer even when the thickness of the adhesive layer 2 is thin (for example, about 2 μm), it is preferably 650,000 or more, more preferably 750,000 or more, even more preferably 850,000 or more, and particularly preferably 950,000 or more. The Mw of the acrylic polymer may be 2 million or less, 1.8 million or less, 1.6 million or less, 1.4 million or less, 1.2 million or less, or 1.1 million or less.

[0014] From the viewpoint of further suppressing residue on the lead frame, the Mw / Mn of the acrylic polymer may be preferably 1.9 or less, 1.8 or less, or 1.7 or less.The Mw / Mn of the acrylic polymer may be 1.0 or more, 1.2 or more, 1.4 or more, or 1.6 or more.

[0015] The Mw and Mw / Mn of an acrylic polymer are measured by the following procedure. The molecular weight was determined by gel permeation chromatography (GPC) using a high performance liquid chromatograph (Tosoh Corporation, model HLC-8320GPC). Two TSKgel Super Multipore HZ-H (Tosoh Corporation) columns were used, a tetrahydrofuran solution was used as the mobile phase, and a differential refractometer was used as the detector. The measurement conditions were a column temperature of 40°C, a sample concentration of 10mg / mL, a sample injection volume of 10μm, and a flow rate of 0.2mL / min. A calibration curve was created using polystyrene (molecular weights 1,090,000, 775,000, 427,000, 289,000, 190,000, 96,400, 37,900, 10,200, 2,630, and 440) as a standard substance, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured. The molecular weight distribution (Mw / Mn) was calculated from the measured values.

[0016] The acrylic polymer is a polymer containing at least an alkyl (meth)acrylate as a monomer unit, and may be a polymer containing other monomers as monomer units in addition to the alkyl (meth)acrylate.

[0017] The alkyl group in the alkyl (meth)acrylate (the alkyl group portion other than the (meth)acryloyl group) may be linear or branched. The number of carbon atoms in the alkyl group may be 2 or more or 3 or more, and may be 30 or less, 20 or less, 10 or less, 7 or less, 5 or less, or 4 or less, or may be 2 or 4.

[0018] Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate.

[0019] The content of alkyl (meth)acrylate may be 70 mass% or more, 75 mass% or more, or 80 mass% or more, and may be 92 mass% or less, 90 mass% or less, or 88 mass% or less, based on the total amount of monomer units in the acrylic polymer.

[0020] The other monomers preferably contain (meth)acryloylmorpholine from the viewpoint of further suppressing the residue on the lead frame when the temporary protective film is peeled off. That is, from the same viewpoint, the acrylic polymer preferably contains alkyl(meth)acrylate and (meth)acryloylmorpholine as monomer units.

[0021] The content of (meth)acryloylmorpholine may be 7 mass% or more, 7.5 mass% or more, 8 mass% or more, 8.5 mass% or more, or 9.0 mass% or more, and may be 20 mass% or less, 18 mass% or less, 17 mass% or less, 16.5 mass% or less, or 16 mass% or less, based on the total amount of monomer units in the acrylic polymer.

[0022] The mass ratio of the (meth)acryloylmorpholine content to the alkyl (meth)acrylate content ((meth)acryloylmorpholine / alkyl (meth)acrylate) may be 0.08 / 1 or more, 0.09 / 1 or more, or 0.1 / 1 or more, and may be 0.3 / 1 or less, 0.25 / 1 or less, 0.23 / 1 or less, 0.21 / 1 or less, or 0.2 / 1 or less.

[0023] The other monomers may include a monomer having a crosslinkable group (crosslinkable monomer). The crosslinkable monomer has a polymerizable group that is copolymerizable with alkyl (meth)acrylate and (meth)acryloylmorpholine in addition to the crosslinkable group. The polymerizable group may be, for example, an ethylenically unsaturated group. The crosslinkable group may be, for example, an acidic group. The acidic group may be, for example, a carboxyl group or a sulfo group, and is preferably a carboxyl group.

[0024] Examples of crosslinkable monomers having a carboxyl group include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, monohydroxyethyl phthalate acrylate, and 2-acryloyloxyethyl succinate.

[0025] The content of the crosslinkable monomer may be 1 mass % or more, 2 mass % or more, or 3 mass % or more, and may be 10 mass % or less, 6 mass % or less, or 4 mass % or less, based on the total amount of monomer units in the acrylic polymer.

[0026] The other monomer may include, for example, a monomer having a polymerizable group (e.g., an ethylenically unsaturated group) and a hydroxyl group. Examples of this monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and hydroxyalkyl cycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0027] The acid value of the acrylic polymer may be 10 mgKOH / g or more, or 20 mgKOH / g or more, and 40 mgKOH / g or less, or 30 mgKOH / g or less. The hydroxyl value of the acrylic polymer may be 1 mgKOH / g or more, or 2 mgKOH / g or more, and 10 mgKOH / g or less, or 5 mgKOH / g or less. The acid value and hydroxyl value of the acrylic polymer are measured according to the method described in JIS K0070.

[0028] The content of the acrylic polymer, based on the total amount of the adhesive layer 2, may be 80 mass % or more, 85 mass % or more, or 90 mass % or more, and may be 99.5 mass % or less, or 99 mass % or less.

[0029] The adhesive layer 2 may further contain a crosslinking agent, or may not contain a crosslinking agent. The crosslinking agent is a crosslinking agent capable of crosslinking with the crosslinkable group in the acrylic polymer. As such a crosslinking agent, a known crosslinking agent can be used. When the crosslinkable group in the acrylic polymer is an acidic group, the crosslinking agent preferably has an epoxy group. The number of epoxy groups in the crosslinking agent may be 2 or more, 3 or more, 4 or less, or may be 4.

[0030] In one embodiment, the crosslinking agent may be a crosslinking agent having an amino group in addition to an epoxy group. The amino group may be an amino group (substituted amino group) in which a hydrogen atom in a -NH2 group is substituted, or may be a tertiary amino group. Such a crosslinking agent may have a group represented by the following formula (1). [ka] The crosslinking agent may have one or two groups represented by the above formula (1).

[0031] The crosslinking agent may be a crosslinking agent represented by the following formula (2): [ka] In the formula, X represents a divalent hydrocarbon group.

[0032] The divalent hydrocarbon group represented by X may be a divalent hydrocarbon group having a ring. The ring may be an alicyclic ring or an aromatic ring. The number of carbon atoms constituting the ring may be 5 or more, 8 or less, or 6. The number of rings in the divalent hydrocarbon group may be 1 or more, 3 or less, or 1 or 2. When the divalent hydrocarbon group contains multiple rings, the multiple rings may be bonded directly to each other or may be bonded via an alkylene group having 1 to 3 carbon atoms.

[0033] The divalent hydrocarbon group represented by X preferably has a cycloalkylene group. The number of carbon atoms in the cycloalkylene group may be 5 or more and 8 or less. The cycloalkylene group is preferably a cyclohexylene group.

[0034] In one embodiment, the crosslinking agent may be a crosslinking agent having an ether group (without an amino group) in addition to an epoxy group. Such a crosslinking agent may have a group represented by the following formula (3). [ka] The number of groups represented by the above formula (3) in the crosslinking agent may be 2 or more, or 3 or more, and may be 4 or less, or may be 2 or 4.

[0035] The crosslinking agent may be a crosslinking agent represented by the following formula (4): [ka] In the formula, m represents an integer of 2 or more, n represents an integer of 0 or more, and A represents a residue obtained by removing a hydroxyl group from an (m+n)-valent polyhydric alcohol.

[0036] m may be an integer of 3 or greater, or an integer of 4 or less, or may be 2 or 4. n may be an integer of 1 or greater, or an integer of 2 or less, or may be 0 or 2. m+n may be an integer of 2 or greater, or an integer of 6 or less.

[0037] The polyhydric alcohol in A may be an aliphatic polyhydric alcohol or an alicyclic polyhydric alcohol, or may be a polyhydric alcohol having an ether group. The number of carbon atoms in the aliphatic polyhydric alcohol or alicyclic polyhydric alcohol may be 2 or more, 3 or more, or 4 or more, and may be 10 or less, 9 or less, or 8 or less. The polyhydric alcohol having an ether group may be a polyalkylene glycol such as polyethylene glycol.

[0038] The content of the crosslinking agent may be 0.5 mass% or more, 15 mass% or less, or 10 mass% or less, based on the total amount of the adhesive layer 2, and is preferably 1 mass% or more, 2 mass% or more, or 2.5 mass% or more, from the viewpoint of preventing deterioration of the appearance of the adherend after the temporary protective film is peeled off from the adherend.

[0039] The content of the crosslinking agent may be 0.5 parts by mass or more, 15 parts by mass or less, or 10 parts by mass or less, relative to 100 parts by mass of the acrylic polymer content, and is preferably 1 part by mass or more, 2 parts by mass or more, or 3 parts by mass or more, from the viewpoint of preventing deterioration of the appearance of the adherend after the temporary protective film is peeled off from the adherend.

[0040] The adhesive layer 2 may further contain other components in addition to the acrylic polymer and the crosslinking agent. Examples of the other components include a polymer other than the acrylic polymer and a coupling agent.

[0041] The thickness of the adhesive layer 2 may be 1 μm or more, or 2 μm or more, and may be 20 μm or less, 15 μm or less, 10 μm or less, 5 μm or less, 4 μm or less, or 3 μm or less.

[0042] In another embodiment, the temporary protective film may further include a cover film provided on the surface of the adhesive layer opposite to the support film. That is, the temporary protective film may include a support film, an adhesive layer, and a cover film in this order. The cover film may be a polyethylene terephthalate film. The thickness of the cover film may be 10 μm or more and 100 μm or less.

[0043] In another embodiment, the temporary protective film may further include a non-adhesive layer provided on the side of the support film opposite to the adhesive layer. The non-adhesive layer may be a resin layer that has substantially no adhesiveness to an adherend at 0 to 270°C. The non-adhesive layer may contain a thermoplastic resin, a thermosetting resin (cured product), or a resin that is a combination thereof. The non-adhesive layer may further contain a filler (e.g., ceramic powder, glass powder, silver powder, copper powder, resin particles, rubber particles), a coupling agent, etc. The thickness of the non-adhesive layer may be 1 μm or more and 10 μm or less.

[0044] The temporary protective film can be produced, for example, by a method including a step of applying a varnish containing an acrylic polymer and a crosslinking agent onto a support film and removing the solvent from the coating to form an adhesive layer.

[0045] Next, a method for manufacturing a semiconductor device using the above-mentioned temporary protective film will be described. The method for manufacturing a semiconductor device according to an embodiment includes, in this order, a step S1 for attaching a temporary protective film to one side of a substrate, a step S2 for mounting a semiconductor element on the surface of the substrate opposite to the temporary protective film, a step S3 for sealing the semiconductor element, and a step S4 for peeling off the temporary protective film from the substrate. Hereinafter, as an example, a method for manufacturing a semiconductor device (semiconductor device package) in which the substrate is a lead frame will be described in more detail.

[0046] 2 is a cross-sectional view illustrating one embodiment (step S1) of a method for manufacturing a semiconductor device. In step S1, as shown in FIG. 2, a temporary protective film 10 is attached to a back surface, which is one surface of a lead frame 11 having a die pad 11a and an inner lead 11b. The temporary protective film 10 is attached in a direction such that an adhesive layer of the temporary protective film 10 contacts the lead frame 11.

[0047] The lead frame 11 may be made of, for example, an iron-based alloy such as alloy 42, copper, or a copper-based alloy. The lead frame 11 may have a molded body made of copper or a copper-based alloy and a coating layer of palladium, gold, silver, or the like that coats the surface of the molded body.

[0048] The temporary protective film 10 has excellent adhesive strength at room temperature (e.g., 25°C), and can be attached to the lead frame 11 at room temperature. The temporary protective film 10 may be attached to the lead frame 11 while being heated and pressed. In this case, the heating temperature may be 150°C or higher and 400°C or lower. The pressure may be 0.5 MPa or higher and 30 MPa or lower. The heating and pressing time may be 1 second or longer and 60 seconds or shorter.

[0049] 3 is a cross-sectional view for explaining one embodiment (steps S2 and S3) of a method for manufacturing a semiconductor device. In step S2, as shown in FIG. 3, a semiconductor element 14 is mounted on the surface of the die pad 11a opposite to the temporary protective film 10. The semiconductor element 14 is bonded to the die pad 11a via an adhesive (for example, silver paste). After bonding the semiconductor element 14 to the die pad 11a, reflow connection (CuClip connection, etc.) may be performed at a maximum temperature of 250 to 440°C or 250 to 400°C for 1 to 30 minutes.

[0050] Next, the semiconductor element 14 is connected to the inner lead 11b using the wire 12. The wire 12 may be, for example, a gold wire, a copper wire, or a palladium-coated copper wire. The wire 12 may be bonded to the semiconductor element 14 and the inner lead 11b using ultrasonic waves and a pressing pressure while being heated at, for example, 200 to 350°C.

[0051] 3, an encapsulating layer 13 is formed to encapsulate the semiconductor element 14 and the wires 12. This results in a temporarily protected encapsulated body 20 having the lead frame 11, the semiconductor element 14, and the encapsulating layer 13.

[0052] The sealing layer 13 is formed by sealing molding using a sealing material. By the sealing molding, a sealed molded body 20 having a plurality of semiconductor elements 14 and a sealing layer 13 that collectively seals them may be obtained. During the sealing molding, the temporary protective film 10 is provided, thereby preventing the sealing material from wrapping around to the back side of the lead frame 11.

[0053] The temperature during the formation of the sealing layer 13 (temperature of the sealing material) may be 140 to 200° C., or 160 to 180° C. The pressure during the formation of the sealing layer may be 6 to 15 MPa, or 7 to 10 MPa. The sealing molding time may be 1 to 5 minutes, or 2 to 3 minutes.

[0054] The sealing material may contain, for example, an epoxy resin such as cresol novolac epoxy resin, phenol novolac epoxy resin, biphenyl diepoxy resin, naphthol novolac epoxy resin, etc. The sealing material may contain a filler, a flame retardant substance such as a bromine compound, a wax component, etc.

[0055] After the formation of 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 sealed molded body 20. When the sealing layer 13 is cured, the temporary protective film 10 may be peeled off at any time before or after the sealing layer 13 is cured.

[0056] The temperature at which the temporary protective film 10 is peeled off is not particularly limited, but may be room temperature (for example, 5 to 35°C). This temperature may be equal to or higher than the glass transition temperature of the adhesive layer. In this case, the temporary protective film 10 has better peelability from the lead frame 11 and the sealing material. If the Tg of the acrylic polymer in the adhesive layer is, for example, 5°C or lower or 0°C or lower, the Tg of the adhesive layer becomes equal to or lower than room temperature, and good peelability at room temperature is easily obtained.

[0057] When the lead frame 11 includes a plurality of patterns having the die pad 11a and the inner lead 11b, the encapsulated body 20 can be divided as necessary to obtain a plurality of semiconductor devices (semiconductor packages) 100 of Fig. 4 each having one semiconductor element. That is, when the lead frame 11 has a plurality of die pads 11a and a semiconductor element 14 is mounted on each of the plurality of die pads 11a, the manufacturing method according to one embodiment may further include a step of peeling the temporary protective film 10 from the encapsulated body 20 and then dividing the encapsulated body 20 to obtain a semiconductor device (semiconductor package) 100 having one die pad 11a and a semiconductor element 14.

[0058] The temporary protective film may be long and wound around a core in a reel form. In this case, the temporary protective film is attached to the adherend while being unwound from the reel.

[0059] Fig. 5 is a perspective view showing one embodiment of a reel body. As shown in Fig. 5, a reel body 30 according to one embodiment includes a winding core 31, a temporary protective film 10 wound around the winding core 31, and a side plate 32. The width of the winding core 31 and the temporary protective film 10 (the length in the direction perpendicular to the winding direction) may be 1 mm or more, 5 mm or more, or 10 mm or more, and may be 1000 mm or less, 800 mm or less, or 500 mm or less. In another embodiment, the reel body may not include a side plate. EXAMPLES

[0060] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0061] Example 1 Acrylic polymer A-1 with a weight average molecular weight (Mw) of 600,000 and a molecular weight distribution (Mw / Mn) of 1.7 was dissolved in cyclohexanone to obtain a varnish for forming an adhesive layer. The acrylic polymer A-1 is a copolymer of butyl acrylate / acryloylmorpholine / acrylic acid / other monomers (monomers having a hydroxyl group) = 80 / 16 / 3 / 1 (mass ratio). A polyimide film (thickness: 25 μm, manufactured by Toray DuPont Co., Ltd., product name: Kapton 100EN) was prepared as a support film. The obtained varnish was applied onto one side of the support film. The coating film on the support film was dried by heating at 90 ° C for 1.5 minutes and at 260 ° C for 1.5 minutes to form an adhesive layer with a thickness of 2 μm. This resulted in a temporary protective film.

[0062] (Examples 2 to 3) A temporary protective film was obtained in the same manner as in Example 1, except that the thickness of the adhesive layer was changed as shown in Table 1.

[0063] Example 4 The following formula (B-1): [ka] A varnish was prepared by adding 10 parts by mass of a crosslinking agent B-1 represented by the following formula: and the thickness of the adhesive layer was changed as shown in Table 1. In the same manner as in Example 1, a temporary protective film was obtained.

[0064] Example 5 Instead of 10 parts by mass of the crosslinking agent B-1, a compound represented by the following formula (B-2): [ka] A temporary protective film was obtained in the same manner as in Example 4, except that 7 parts by mass of a crosslinking agent B-2 represented by the following formula was added.

[0065] Example 6 A temporary protective film was obtained in the same manner as in Example 1, except that acrylic polymer A-2 having a weight average molecular weight (Mw) of 1,000,000 and a molecular weight distribution (Mw / Mn) of 1.9 was used instead of acrylic polymer A-1. The acrylic polymer A-2 was a copolymer of butyl acrylate / acryloylmorpholine / acrylic acid / other monomers (monomers having a hydroxyl group)=80 / 16 / 3 / 1 (mass ratio).

[0066] (Examples 7 to 8) A temporary protective film was obtained in the same manner as in Example 6, except that the thickness of the adhesive layer was changed as shown in Table 1.

[0067] Comparative Example 1 Instead of 100 parts by mass of the acrylic polymer A-1, 100 parts by mass of an acrylic polymer a-1 (product name: HTR-280, manufactured by Nagase ChemteX Corporation) having a weight average molecular weight (Mw) of 990,000 and a molecular weight distribution (Mw / Mn) of 3.0 was used. [ka] A varnish was prepared using 30 parts by mass of a crosslinking agent B-3 represented by the formula: and the thickness of the adhesive layer was changed as shown in Table 1. In the same manner as in Example 1, a temporary protective film was obtained.

[0068] Comparative Example 2 Instead of 100 parts by mass of acrylic polymer A-1, a varnish was prepared using 30 parts by mass of acrylic polymer a-1, 70 parts by mass of acrylic polymer a-2 (product name: WS-023 EK30, manufactured by Nagase ChemteX Corporation) having a weight average molecular weight (Mw) of 720,000 and a molecular weight distribution (Mw / Mn) of 4.4, and 10 parts by mass of crosslinking agent B-3. A temporary protective film was obtained in the same manner as in Example 1, except that the thickness of the adhesive layer was changed as shown in Table 1.

[0069] (Residue evaluation) Each temporary protective film was attached to a CDA194 palladium-plated Cu plate (lead frame, manufactured by Shinko Electric Industries Co., Ltd.) with the adhesive layer facing the lead frame at 25°C and a load of 20N. The resulting laminate was heated in an oven in an air atmosphere at 180°C for 60 minutes, then at 200°C for 60 minutes, while changing the conditions. The surface of the lead frame opposite the temporary protective film was plasma-treated in an argon gas atmosphere (flow rate: 20sccm), at 150W, for 15 seconds.

[0070] Using a mold forming machine (manufactured by Apic Yamada Co., Ltd.), a sealing layer was formed on the surface of the lead frame opposite to the temporary protective film with a sealing material (product name: GE-300, manufactured by Showa Denko Materials Co., Ltd.). The sealing conditions were 175°C, 6.8 MPa, and 2 minutes. Then, at 25°C, each temporary protective film was peeled off at a speed of 50 mm / min in a direction of 180° with respect to the surface of the lead frame. The state of the adhesive layer remaining on each of the lead frame and the sealing layer after the temporary protective film was peeled off was confirmed. The ratio of the area occupied by the residue of the adhesive layer to the area of ​​the surface of the lead frame and the area of ​​the surface of the sealing layer was calculated. Based on the ratio of the area occupied by the residue, the following criteria were used for evaluation. The results are shown in Table 1. A: Less than 5% B: 5% or more but less than 15% C: 15% or more

[0071] [Table 1] [Explanation of symbols]

[0072] Reference Signs List 1: support film, 2: adhesive layer, 10: temporary protective film, 11: lead frame, 11a: die pad, 11b: inner lead, 12: wire, 13: sealing layer, 14: semiconductor element, 20: sealed molded body, 100: semiconductor device.

Claims

1. A support film; an adhesive layer provided on the support film, A temporary protective film for use in the production of a semiconductor device, wherein the adhesive layer contains an acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less.

2. The temporary protective film according to claim 1 , wherein the acrylic polymer contains an alkyl (meth)acrylate and a (meth)acryloylmorpholine as monomer units.

3. The temporary protective film according to claim 1 or 2, wherein the weight average molecular weight of the acrylic polymer is 850,000 or more.

4. A step of attaching a temporary protective film to one side of the substrate; Mounting a semiconductor element on a surface of the substrate opposite to the temporary protective film; encapsulating the semiconductor element; peeling the temporary protective film from the substrate; A method for manufacturing a semiconductor device, comprising the steps of: The temporary protective film is A support film; an adhesive layer provided on the support film, The manufacturing method, wherein the adhesive layer contains an acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less.

5. The method according to claim 4 , wherein the acrylic polymer comprises an alkyl (meth)acrylate and a (meth)acryloylmorpholine as monomer units.

6. The method according to claim 4 or 5, wherein the weight average molecular weight of the acrylic polymer is 850,000 or more.

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