Sheet material

Abstract

The object of the present invention is to provide a sheet material that achieves both good pickupability for semiconductor chips and secure retention of semiconductor chips. [Solution] The sheet material of the present invention is a sheet material used for holding semiconductor chips, and is composed of a material containing a thermoplastic elastomer, characterized in that the tack force is 10 kPa or more when the material constituting the portion that holds the semiconductor chip has a thickness of 150 μm. Preferably, the material constituting the portion that holds the semiconductor chip is composed of a material containing the thermoplastic elastomer and a polyolefin.

Description

Technical Field

[0001] The present invention relates to a sheet material.

Background Art

[0002] Conventionally, it has been known to hold and handle individually fragmented semiconductor chips with a holding member such as a storage tray (see, for example, Patent Documents 1 and 2).

[0003] The holding member disclosed in Patent Document 1 has an adhesive material having an adhesive surface to which a plurality of chips are adhered, and adheres the plurality of chips at once by pressing the chips against the adhesive surface.

[0004] Further, the holding member disclosed in Patent Document 2 includes a bottomed square tube-shaped tray and a flexible adhesive film that detachably holds minute parts inside the tray, and sucks the adhesive film by exhausting air from an exhaust hole provided at the bottom of the tray.

[0005] When the holding force of the adhesive surface is too strong, it becomes difficult to pick up the chip, and in some cases, the chip may be damaged.

[0006] On the other hand, when the holding force is too weak, the chip cannot be continuously held. For example, during conveyance, the chip may move and contact between adjacent chips may occur, and the chip may be damaged.

[0007] Thus, in the conventional sheet material for holding semiconductor chips, it has been difficult to achieve both suitable pick-up property of the semiconductor chips and ensuring of the holding force of the semiconductor chips.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

[0009] The object of the present invention is to provide a sheet material that achieves both good pickupability for semiconductor chips and secure retention of semiconductor chips. [Means for solving the problem]

[0010] These objectives are achieved by the following inventions (1) to (11). (1) A sheet material used to hold semiconductor chips, Composed of materials including thermoplastic elastomers, A sheet material characterized in that the tack force is 10 kPa or more when the material constituting the portion that holds the semiconductor chip has a thickness of 150 μm.

[0011] (2) The sheet material described in (1) above, wherein the material constituting the portion that holds the semiconductor chip is composed of the thermoplastic elastomer and the polyolefin.

[0012] (3) The sheet material described in (2) above, wherein the material constituting the portion that holds the semiconductor chip is composed of the thermoplastic elastomer and polypropylene.

[0013] (4) The sheet material according to (2) or (3) above, in which the content of the thermoplastic elastomer in the material constituting the portion that holds the semiconductor chip is X1 [mass%] and the content of the polyolefin is X2 [mass%], and the relationship 0.25 ≤ X1 / X2 is satisfied.

[0014] (5) The sheet material according to any one of (1) to (4) above, comprising at least one selected from the group consisting of an ethylene-vinyl acetate copolymer, an ethylene-methacrylic acid copolymer, an olefin copolymer, and a hydrogenated styrenic thermoplastic elastomer as the thermoplastic elastomer.

[0015] (6) A base material, The sheet material according to any one of (1) to (5) above, having a holding layer provided on one surface side of the base material and composed of a material containing at least the thermoplastic elastomer, for holding the semiconductor chip.

[0016] (7) The sheet material according to (6) above, wherein the base material and the holding layer contain the same kind of material.

[0017] (8) The sheet material according to (6) or (7) above, wherein the base material is composed of a material containing polyolefin.

[0018] (9) The sheet material according to (8) above, wherein the base material is composed of a material containing polypropylene.

[0019] (10) The sheet material according to any one of (6) to (9) above, when the thickness of the holding layer is T1 [μm] and the thickness of the base material is T2 [μm], satisfying the relationship of 0.03 ≦ T1 / T2 ≦ 30.

[0020] (11) The sheet material according to any one of (1) to (10) above, having a volume resistivity of 1.0×10 15 (Ω·m) or less.

Advantages of the Invention

[0021] According to the present invention, it is possible to provide a sheet material that achieves both good pick-up property of a semiconductor chip and secure holding force of the semiconductor chip.

Brief Description of the Drawings

[0022] [Figure 1]It is a cross-sectional view showing one configuration example of the sheet material of the present invention. [Figure 2] It is a cross-sectional view showing another configuration example of the sheet material of the present invention. [Figure 3] It is a view showing one configuration example of a semiconductor chip holding member to which the sheet material of the present invention is applied, (a) is a plan view, and (b) is a cross-sectional view.

Embodiments for Carrying Out the Invention

[0023] Hereinafter, preferred embodiments of the present invention will be described in detail. [1] Sheet material First, the sheet material of the present invention will be described.

[0024] FIG. 1 is a cross-sectional view showing one configuration example of the sheet material of the present invention. FIG. 2 is a cross-sectional view showing another configuration example of the sheet material of the present invention.

[0025] The sheet material 1 of the present invention is a sheet material used for holding a semiconductor chip, is composed of a material containing a thermoplastic elastomer, and has a tack force of 10 kPa or more when the material constituting the portion 1a for holding the semiconductor chip has a thickness of 150 μm.

[0026] Thereby, the sheet material 1 of the present invention can suitably achieve both the pick-up property of the semiconductor chip and the securing of the holding force of the semiconductor chip.

[0027] More specifically, by being composed of a material containing a thermoplastic elastomer and having a tack force of 10 kPa or more when the material constituting the portion 1a for holding the semiconductor chip has a thickness of 150 μm, the portion 1a for holding the semiconductor chip has appropriate tackiness, and it becomes possible to achieve both the pick-up property of the semiconductor chip and the securing of the holding force of the semiconductor chip.

[0028] In other words, in the sheet material 1, the portion 1a that holds the semiconductor chip can exhibit suitable holding force to the semiconductor chip, and at the time of pickup, can exhibit sufficient tackiness to provide suitable peelability between the sheet material 1 and the semiconductor chip.

[0029] Furthermore, sheet materials manufactured in long lengths are generally transported and stored in a rolled state. However, even when the sheet material is rolled up in this manner, the sheet material 1 of the present invention can effectively prevent the sheet materials 1 from sticking together when wound up, and can be effectively pulled out when in use.

[0030] In this invention, "elastomer" is a general term for polymer materials that have viscoelasticity and small intermolecular interactions, resulting in a smaller Young's modulus and larger fracture strain compared to other materials. In particular, "thermoplastic elastomer" refers to a polymer material that softens when heated and returns to a rubbery state when cooled.

[0031] In this invention, "tack" refers to the stickiness of the adhesive surface. "Tack force" refers to how instantly the material adheres upon contact, or the resistance force when immediately separating it after contact.

[0032] Furthermore, in this invention, the tack force of the material constituting the part 1a that holds the semiconductor chip is a value measured by a method compliant with JIS Z0237:2022.

[0033] Specifically, the test is performed using a tacking test machine TAC-1000 manufactured by Resca, Inc., by applying a Constant Load to a test specimen formed from the material into a 150 μm thick sheet, and maintaining that pressure until a set time has elapsed. A 5.0 mm diameter stainless steel probe is brought into contact with the specimen from above. The speed at which the probe is brought into contact with the specimen is set to 1 mm / sec, the contact load to 200 gf, the contact time to 1 second, and the probe and plate temperatures to 25°C. After that, the probe is peeled upward at a peeling speed of 10 mm / sec, and the force required to peel it off is measured as the "tack force".

[0034] Furthermore, in this invention, the thickness "150 μm" refers to the thickness of the test specimen prepared when measuring the tack force of the material constituting the semiconductor chip holding portion 1a, and not to the thickness of the "semiconductor chip holding portion 1a" that the sheet material 1 possesses.

[0035] The excellent effects of the present invention are obtained when the sheet material 1 has the above-described configuration, and cannot be obtained when it does not have the above-described configuration.

[0036] For example, if the part 1a that holds the semiconductor chip does not contain a thermoplastic elastomer, it is not possible to set the tack force of the material constituting the part 1a that holds the semiconductor chip to an appropriate level. Specifically, it becomes difficult to set the tack force of the material constituting the part 1a that holds the semiconductor chip to a range of 10 kPa or more when the thickness of the material is 150 μm.

[0037] Furthermore, for example, if the tack force of the material constituting the part 1a that holds the semiconductor chip is less than 10 kPa, the holding force of the semiconductor chip will be insufficient.

[0038] In the sheet material 1 of the present invention, if the material constituting the portion 1a that holds the semiconductor chip has a thickness of 150 μm, the tack force may be 10 kPa or more, but is preferably 20 kPa or more, and more preferably 30 kPa or more. This makes the effects of the present invention described above even more pronounced.

[0039] Furthermore, in the sheet material 1 of the present invention, when the material constituting the portion 1a that holds the semiconductor chip has a thickness of 150 μm, the upper limit of the tack force is not particularly limited, but is preferably 125 kPa or less, more preferably 100 kPa or less, and even more preferably 75 kPa or less.

[0040] This makes the effects of the present invention described above even more pronounced. In particular, the pickup properties of semiconductor chips can be made more favorable. Furthermore, the sheet material 1 can be suitably formed into a film, and adhesion between the sheet materials 1 when the sheet material 1 is wound into a roll can be more effectively suppressed.

[0041] The sheet material of the present invention may have any portion made of a material containing a thermoplastic elastomer, and may consist only of a retaining layer 3 made of a material containing at least a thermoplastic elastomer, as shown in the sheet material 1 in Figure 1. However, the sheet material 1 shown in Figure 2 has a base material 2 and a retaining layer 3 provided on one side of the base material 2, which is made of a material containing at least a thermoplastic elastomer and holds a semiconductor chip.

[0042] In the sheet material 1 shown in Figures 1 and 2, the surface of the retaining layer 3 becomes the portion 1a that holds the semiconductor chip.

[0043] By providing a base material 2 that supports the retaining layer 3, in addition to a portion (retaining layer 3) made of a material containing at least a thermoplastic elastomer, it is possible to more effectively prevent the sheet materials 1 from sticking together when, for example, the sheet material 1 is wound into a roll. Furthermore, since the material constituting the base material 2, in other words, the resin material described later, is generally less expensive than the thermoplastic elastomer constituting the retaining layer 3, it also contributes to reducing the overall cost of the sheet material 1.

[0044] [1-1] Base material The base material 2 is in the form of a sheet and has the function of supporting the retaining layer 3. The base material 2 is typically composed of a material that primarily contains resin material.

[0045] [1-1-1] Resin materials The resin material constituting the base material 2 is not particularly limited as long as it has good compatibility with the thermoplastic elastomer, but examples include polyester resins (ester polymers) such as polyolefin resins, polyvinyl chloride resins, polystyrene resins, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polyester thermoplastic elastomers, polyurethane, polyimide, polyamide, polyether ketones such as polyether ether ketone, polyether sulfone, fluororesin, silicone resin, cellulose resin, acrylic resin, polyvinyl isoprene, and polycarbonate (carbonate polymer), and thermoplastic resins such as one or more selected from these can be used in combination.

[0046] In particular, it is preferable that the base material 2 is composed of a material containing a polyolefin resin. This makes the effects described above even more pronounced.

[0047] The polyolefin resin is not particularly limited, but examples include polyethylene resins such as polypropylene, linear low-density polyethylene, low-density polyethylene, and ultra-low-density polyethylene; polyethylene copolymers such as ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-methacrylate copolymer (EMAA), and ionomers such as ethylene-based ionomers as zinc ion crosslinks, sodium ion crosslinks, or potassium ion crosslinks. One or more of these can be used in combination, and polypropylene is preferred. This can make the effects described above even more pronounced.

[0048] [1-1-2] Other ingredients Base material 2 may contain components other than those mentioned above (hereinafter referred to as "other components" in this section).

[0049] Examples of such components include conductive materials, softeners such as mineral oil, fillers such as calcium carbonate, silica, talc, mica, and clay, antioxidants, light stabilizers, lubricants, dispersants, neutralizing agents, and colorants. One or more of these can be selected and used in combination.

[0050] Of these, by including a conductive material in the base material 2, the conductive material can function as an antistatic agent, effectively suppressing or preventing the generation of static electricity in the semiconductor element during handling and pickup. Therefore, it is possible to effectively suppress or prevent damage to the semiconductor element caused by the discharge of static electricity, which would result in a decrease in the characteristics of the semiconductor element.

[0051] The conductive material is not particularly limited as long as it is conductive, but examples include surfactants, permanent antistatic polymers (IDPs), metal materials, metal oxide materials, and carbon-based materials, and one or more selected from these can be used in combination.

[0052] However, the content of other components in base material 2 is preferably 30.0% by mass or less, more preferably 25.0% by mass or less, and even more preferably 20.0% by mass or less.

[0053] [1-1-3] Other conditions Even if the materials constituting the retaining layer 3 are the same in sheet material 1, changing the thickness of the base material 2 can improve the overall heat resistance, dimensional stability, prevent roll twisting during film formation, and reduce costs of sheet material 1.

[0054] The thickness of the substrate 2 is preferably 5 μm or more and 300 μm or less, more preferably 10 μm or more and 250 μm or less, and even more preferably 15 μm or more and 200 μm or less.

[0055] This allows for a more optimal tack force for the sheet material 1 as a whole. Furthermore, it enables the base material 2 to function more reliably, allowing for improved workability in handling semiconductor chips. Additionally, it allows for more accurate pickup of semiconductor chips.

[0056] Furthermore, the base material 2 may be composed of a laminate (multilayer) formed by stacking multiple layers made of different materials.

[0057] [1-2] Retention layer The retaining layer 3 is composed of a material containing at least a thermoplastic elastomer and constitutes a portion 1a in the sheet material 1 that holds the semiconductor chip.

[0058] In the following explanation, the material constituting the part 1a that holds the semiconductor chip will be described as the material constituting the holding layer 3.

[0059] The retaining layer 3 is composed of a material containing at least a thermoplastic elastomer, but it is preferable that it is composed of a material containing a thermoplastic elastomer and a polyolefin. This makes it possible to more effectively achieve the aforementioned tack force requirements.

[0060] [1-2-1] Thermoplastic elastomers Examples of thermoplastic elastomers include styrene-based thermoplastic elastomers, ethylene-based thermoplastic elastomers, olefin-based thermoplastic elastomers such as polypropylene-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and olefin-based copolymers. One or more selected from these can be used in combination, but it is preferable that at least one selected from the group consisting of styrene-based thermoplastic elastomers, ethylene-based thermoplastic elastomers, and olefin-based copolymers be used. This makes the effects described above even more pronounced.

[0061] Examples of styrene-based thermoplastic elastomers (TPS) include hydrogenated styrene-based thermoplastic elastomers such as partially hydrogenated styrene-butadiene-styrene block copolymer (SBS), fully hydrogenated styrene-butadiene-styrene block copolymer (SBS), styrene-butadiene-styrene block copolymer (SBS), styrene-isobutylene-styrene block copolymer (SIBS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene (SIS), and styrene-ethylene-propylene-butylene block copolymer (SEPS).

[0062] Examples of ethylene-based thermoplastic elastomers include ethylene-vinyl acetate copolymer (EVA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EAA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate copolymer (EBA).

[0063] Examples of olefin copolymers include ethylene copolymers, propylene copolymers, and butene copolymers, and more specifically, ethylene-butene copolymers and propylene-butene copolymers.

[0064] The retaining layer 3 preferably contains at least one thermoplastic elastomer selected from the group consisting of ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, olefin copolymer, and hydrogenated styrene-based thermoplastic elastomer, among the compounds described above. This can make the effects described above even more pronounced.

[0065] The content of thermoplastic elastomer in the retaining layer 3 is preferably 20% by mass or more and 100% by mass or less, more preferably 25% by mass or more and 90% by mass or less, and even more preferably 30% by mass or more and 80% by mass or less. This makes the effects described above even more pronounced.

[0066] [1-2-2] Polyolefins The polyolefin constituting the retaining layer 3 is not particularly limited, but examples include polyethylene resins such as polypropylene, linear low-density polyethylene, low-density polyethylene, and ultra-low-density polyethylene, polyethylene copolymers such as ethylene-methacrylate copolymers (EMAA), and ionomers such as ethylene-based ionomers as zinc ion crosslinks, sodium ion crosslinks, or potassium ion crosslinks. One or more selected from these can be used in combination, but polypropylene is preferred.

[0067] In other words, it is preferable that the material constituting the retaining layer 3 is composed of a material including a thermoplastic elastomer and polypropylene. This can make the effects described above even more pronounced.

[0068] The polyolefin content in the retaining layer 3 is preferably 0% by mass or more and 90% by mass or less, more preferably 10% by mass or more and 80% by mass or less, and even more preferably 20% by mass or more and 70% by mass or less. This makes the effects described above even more pronounced.

[0069] By adjusting the content of thermoplastic elastomer and polyolefin in the retaining layer 3, the tack force of the semiconductor chip-holding portion 1a can be suitably controlled.

[0070] In the retaining layer 3 (the part that holds the semiconductor chip), when the content of thermoplastic elastomer is X1 [mass%] and the content of polyolefin is X2 [mass%], it is preferable that the relationship 0.25 ≤ X1 / X2 is satisfied, more preferably that 0.5 ≤ X1 / X2 is satisfied, and even more preferably that 0.75 ≤ X1 / X2 is satisfied. This can make the effects described above even more pronounced.

[0071] In the sheet material 1, it is preferable that the base material 2 and the retaining layer 3 contain the same type of material. More specifically, it is more preferable that the base material 2 is composed of a material containing polyolefin and the retaining layer 3 is composed of a material containing thermoplastic elastomer and polyolefin, and even more preferable that the base material 2 is composed of a material containing polypropylene and the retaining layer 3 is composed of a material containing thermoplastic elastomer and polypropylene.

[0072] This results in better adhesion between the base material 2 and the retaining layer 3, as well as better tack strength for the sheet material 1 as a whole.

[0073] In this specification, "same type" means any material having a common repeating chemical structure (unit structure). For example, if both the base material 2 and the retaining layer 3 are composed of polypropylene, they are considered to be the same type of material, even if their weight-average molecular weight, glass transition temperature, softening point, and other conditions differ.

[0074] [1-2-3] Other ingredients The retaining layer 3 may contain components other than those mentioned above (hereinafter referred to as "other components" in this section).

[0075] Examples of such components include conductive materials, tackifiers, anti-aging agents, tack modifiers, fillers, colorants, flame retardants, softeners, antioxidants, and surfactants. One or more of these can be selected and used in combination.

[0076] Of these, the conductive material is not particularly limited as long as it has conductivity, but a material similar to the conductive material described above as being included in the base material 2 can be suitably used.

[0077] The inclusion of such conductive materials allows them to function as antistatic agents, effectively suppressing or preventing static electricity from being generated in semiconductor devices during handling and pickup. Therefore, damage to semiconductor devices caused by static discharge, resulting in a decrease in the properties of the semiconductor devices, can be effectively suppressed or prevented.

[0078] However, the content of other components in the retaining layer 3 is preferably 30.0% by mass or less, more preferably 25.0% by mass or less, and even more preferably 20.0% by mass or less.

[0079] [1-2-4] Other conditions In sheet material 1, even if the materials constituting the retaining layer 3 are the same, the overall tack force of sheet material 1 can be adjusted by changing the thickness of the retaining layer 3.

[0080] In the sheet material 1, the thickness of the retaining layer 3 is preferably 1 μm or more and 300 μm or less, more preferably 2 μm or more and 250 μm or less, and even more preferably 3 μm or more and 200 μm or less. This allows for a more optimal tack strength for the sheet material 1 as a whole.

[0081] Furthermore, even if the materials constituting the base material 2 and the retaining layer 3 are the same in the sheet material 1, the overall tack force of the sheet material 1 can be adjusted by changing the ratio of the thickness of the retaining layer 3 to the thickness of the base material 2.

[0082] In the sheet material 1, when the thickness of the retaining layer 3 is T1 [μm] and the thickness of the base material 2 is T2 [μm], it is preferable that the relationship 0.03 ≤ T1 / T2 ≤ 30 is satisfied, more preferably that the relationship 0.04 ≤ T1 / T2 ≤ 25 is satisfied, and even more preferably that the relationship 0.05 ≤ T1 / T2 ≤ 20 is satisfied.

[0083] This makes it possible to further optimize the tack strength of the sheet material 1 as a whole.

[0084] The retaining layer 3 may also be composed of a laminate (multilayer) made up of multiple layers of different materials stacked together.

[0085] [1-3] Other conditions The volume resistivity of sheet material 1 is 1.0 × 10⁻⁶. 15 It is preferable that the value is less than or equal to (Ω·m), and 1.0 × 10 14 It is more preferable that the value be less than or equal to (Ω·m), and 1.0 × 10 13 It is even more preferable that it is less than or equal to (Ω·m).

[0086] This effectively suppresses or prevents the generation of static electricity in semiconductor elements during handling and pickup. Consequently, it effectively suppresses or prevents damage to semiconductor elements caused by static discharge, which would result in a decrease in the characteristics of the semiconductor elements.

[0087] [2] Method for manufacturing sheet material Next, we will explain the manufacturing method for the sheet material as described above.

[0088] A method for manufacturing a sheet material includes at least a step of forming a portion made of a material containing a thermoplastic elastomer. More specifically, for example, it includes a step of forming a retaining layer 3 made of a material containing at least a thermoplastic elastomer on one side of a substrate 2.

[0089] The process of forming the retaining layer 3 includes, for example, a retaining layer forming composition preparation step of preparing a retaining layer forming composition containing the materials that constitute the retaining layer 3, and a composition application step of forming the retaining layer 3 by applying the retaining layer forming composition to one side of the substrate 2.

[0090] Specifically, for example, in the step of preparing the composition for forming the retaining layer, the composition for forming the retaining layer is prepared by mixing the materials constituting the retaining layer 3, for example, a thermoplastic elastomer and a polyolefin.

[0091] Then, in the step of applying the retaining layer-forming composition, the retaining layer-forming composition can be applied to one side of the substrate 2 using known methods such as extrusion lamination or dry lamination to form the retaining layer 3.

[0092] Prior to forming the retaining layer 3, a surface treatment such as corona treatment may be applied to the surface of the substrate 2 to improve adhesion with the retaining layer 3. Alternatively, the film may be formed by co-extruding the substrate forming composition and the retaining layer forming composition.

[0093] [3] Semiconductor chip holder Next, a semiconductor chip holding member to which the sheet material of the present invention is applied will be described. Figure 3 shows an example of a semiconductor chip holding member to which the sheet material of the present invention is applied, where (a) is a plan view and (b) is a cross-sectional view.

[0094] The semiconductor chip holding member 10 is a semiconductor chip holding member used to hold a semiconductor chip, and comprises a sheet material 1 and a ring-shaped frame 11, with the sheet material 1 being joined to one side of the frame 11.

[0095] With this configuration, the semiconductor chip holding member 10 has appropriate tackiness, making it possible to achieve both good semiconductor chip pickability and sufficient holding force for the semiconductor chip.

[0096] [3-1] Sheet material The sheet material 1 of the semiconductor chip holding member 10 has a tack force of 10 kPa or more when the material constituting the part that holds the semiconductor chip has a thickness of 150 μm.

[0097] The sheet material 1 is not particularly limited as long as it is composed of a material containing a thermoplastic elastomer, but it is preferable that it satisfies the preferred conditions described in [1] above. This results in the effects described above.

[0098] In the semiconductor chip holding member 10 shown in Figure 3, the sheet material 1 comprises a base material 2 and a holding layer 3 provided on one side of the base material 2, composed of a material containing at least a thermoplastic elastomer, and holding the semiconductor chip. In other words, the semiconductor chip holding member 10 shown in Figure 3 comprises the sheet material 1 shown in Figure 2. The semiconductor chip holding member 10 may, for example, comprise the sheet material 1 shown in Figure 1 instead of the sheet material 1 shown in Figure 2.

[0099] [3-2] Frame The semiconductor chip holding member 10 has a ring-shaped frame 11, and a sheet material 1 is bonded to one side of this frame 11.

[0100] As the ring-shaped frame 11, for example, one used in dicing sheets can be used.

[0101] As shown in Figure 3, the frame 11 is a frame having an opening 12 in the center, and is a molded body made of, for example, metal such as stainless steel or plastic.

[0102] The thickness of the frame 11 is not particularly limited, but can be between 1.0 mm and 1.5 mm.

[0103] The external shape of the frame 11 is not limited to a circular shape, but may also be polygonal. Similarly, the shape of the opening 12 is not limited to a circular shape.

[0104] Furthermore, the frame 11 may have notches or the like (not shown) formed therein for aligning the orientation and position of semiconductor chips during manufacturing and inspection.

[0105] The sheet material 1 and the frame 11 can be joined by placing the frame 11 on the surface that constitutes the portion 1a of the sheet material 1 that holds the semiconductor chip, in other words, on the surface that has tackiness, and pressing it down. However, in the semiconductor chip holding member 10 shown in Figure 3, the sheet material 1 is joined to one side of the frame 11 via an adhesive layer 13. This allows the sheet material 1 and the frame 11 to be joined more firmly.

[0106] The shape of the sheet material 1 is not particularly limited as long as it can cover the opening 12 of the frame 11, but it is preferably circular.

[0107] [3-3]Adhesive layer The adhesive layer 13 serves to bond the sheet material 1 and the frame 11. In this specification, the term "adhesive layer" refers to a concept that includes both a tack layer and an adhesive layer.

[0108] The adhesive that constitutes the adhesive layer 13 is not particularly limited, but it is preferable that the adhesive layer 13 includes an ultraviolet-curing adhesive.

[0109] UV-curing adhesives have sufficient adhesive strength before the curing reaction by UV light, but their adhesive strength decreases after the curing reaction.

[0110] As a result, after use, by irradiating the adhesive layer 13 of the semiconductor chip holding member 10 with ultraviolet light, the ultraviolet-curable adhesive layer 13 is cured, reducing its adhesive strength, which allows for the sheet material 1 and the frame 11 to be peeled off smoothly.

[0111] The following explanation will primarily focus on the case where the adhesive layer 13 is an adhesive layer containing an ultraviolet-curing adhesive, but will not be limited to this case.

[0112] Such an adhesive layer is composed of a resin composition containing either (1) an adhesive base resin or (2) a curable resin for curing the adhesive layer, with the latter being the main material.

[0113] The following describes in detail each component contained in this resin composition.

[0114] [3-3-1] Base resin The base resin is adhesive and is included in the resin composition to impart adhesiveness to the sheet material 1 and frame 11 to the adhesive layer.

[0115] Examples of such base resins include acrylic resins (adhesives), silicone resins (adhesives), polyester resins (adhesives), polyvinyl acetate resins (adhesives), polyvinyl ether resins (adhesives), styrene elastomer resins (adhesives), polyisoprene resins (adhesives), polyisobutylene resins (adhesives), and urethane resins (adhesives), but among these, acrylic resins are preferred.

[0116] Acrylic resins are preferred as base resins because they have excellent heat resistance and are relatively easy and inexpensive to obtain.

[0117] Acrylic resins refer to polymers (homopolymers or copolymers) whose base polymer is a polymer in which (meth)acrylic acid ester is the main monomer component.

[0118] The (meth)acrylic acid ester is not particularly limited, but alkyl (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate are preferred.

[0119] Alkyl (meth)acrylates are particularly excellent in heat resistance and are relatively easy and inexpensive to obtain.

[0120] Acrylic resins preferably have functional groups (reactive functional groups) that are reactive to crosslinking agents and photopolymerization initiators, such as hydroxyl groups and carboxyl groups (especially hydroxyl groups).

[0121] As a result, the crosslinking agent and photopolymerization initiator are linked to the acrylic resin, which is the polymer component, and the leakage of these crosslinking agents and photopolymerization initiators from the adhesive layer can be effectively suppressed or prevented. Consequently, irradiation of the adhesive layer with ultraviolet light reliably reduces the tackiness of the adhesive layer to the frame 11.

[0122] [3-3-2] Curing resin Curable resins, for example, are those that harden when exposed to ultraviolet light. This hardening process incorporates the base resin into the cross-linked structure of the curable resin, reducing the adhesive strength of the adhesive layer.

[0123] As such curable resins, for example, low molecular weight compounds having at least two polymerizable carbon-carbon double bonds as functional groups that can be three-dimensionally crosslinked by ultraviolet irradiation are used.

[0124] Such curable resins are not particularly limited, but preferably include at least one of the following: esterified (meth)acrylic acid with a polyhydric alcohol, urethane acrylate, and bisphenol A-based epoxy acrylate. This allows for more reliable curing of resins that can be cured by ultraviolet light.

[0125] The curable resin is preferably blended in an amount of 30 to 200 parts by weight per 100 parts by weight of the base resin, and more preferably in an amount of 50 to 140 parts by weight.

[0126] This ensures that the functions exhibited by adding the curable resin and the base resin to the resin composition are reliably exerted by both the curable resin and the base resin.

[0127] [3-3-3] Photopolymerization initiator The adhesive layer's tackiness to the frame 11 decreases upon irradiation with ultraviolet light. However, it is preferable that the resin composition constituting the adhesive layer contains a photopolymerization initiator to facilitate the initiation of polymerization of the curable resin.

[0128] Examples of photopolymerization initiators include 2-2-dimethoxy-1,2-diphenylethane-1-one, benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, and β-chloranthraquinone. One or more selected from these can be used in combination.

[0129] The content of the photopolymerization initiator in the resin composition is preferably 0.1 parts by weight or more and 50 parts by weight or less, and more preferably 0.5 parts by weight or more and 10 parts by weight or less, per 100 parts by weight of the base resin.

[0130] [3-3-4] Crosslinking agent The resin composition constituting the adhesive layer may contain a crosslinking agent. The inclusion of a crosslinking agent allows the adhesive layer to be adjusted to have a more suitable hardness.

[0131] Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, urea resin-based crosslinking agents, methylol-based crosslinking agents, chelate-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, polyvalent metal chelate-based crosslinking agents, acid anhydride-based crosslinking agents, polyamine-based crosslinking agents, and carboxyl group-containing polymer-based crosslinking agents. One or more of these can be selected and used in combination. Among these, isocyanate-based crosslinking agents are preferred.

[0132] Examples of isocyanate-based crosslinking agents include polyisocyanate compounds of polyvalent isocyanates, trimers of polyisocyanate compounds, trimers of terminal isocyanate compounds obtained by reacting polyisocyanate compounds with polyol compounds, or blocked polyisocyanate compounds obtained by encapsulating terminal isocyanate urethane prepolymers with phenol, oximes, etc. One or more selected from these can be used in combination.

[0133] The amount of crosslinking agent in the resin composition is preferably 0.01 parts by weight or more and 30 parts by weight or less, and more preferably 0.1 parts by weight or more and 20 parts by weight or less, per 100 parts by weight of the base resin.

[0134] [3-3-5] Plasticizers The resin composition constituting the adhesive layer may contain a plasticizer. The inclusion of a plasticizer makes it possible to more effectively improve the flexibility of the adhesive layer, which loses its adhesive strength when exposed to ultraviolet light.

[0135] Examples of such plasticizers include phthalate ester plasticizers, aliphatic dibasic acid ester plasticizers, aromatic carboxylic acid ester plasticizers, trimellitic acid ester plasticizers, and adipic acid ester plasticizers. One or more of these can be selected and used in combination.

[0136] The plasticizer content in the resin composition is preferably 0.1 parts by weight or more and 5.0 parts by weight or less, and more preferably 0.5 parts by weight or more and 3.0 parts by weight or less, per 100 parts by weight of the base resin. This allows for a more favorable improvement in the flexibility of the adhesive layer.

[0137] [3-3-6] Other ingredients Furthermore, the resin composition constituting the adhesive layer may also contain components other than those mentioned above (hereinafter referred to as "other components" in this section).

[0138] Examples of such components include conductive materials, tackifiers, anti-aging agents, tack modifiers, fillers, colorants, flame retardants, softeners, antioxidants, and surfactants. One or more of these can be selected and used in combination.

[0139] The conductive material is not particularly limited as long as it is conductive, but examples include surfactants, permanent antistatic polymers (IDPs), metal materials, metal oxide materials, and carbon-based materials, and one or more selected from these can be used in combination.

[0140] The inclusion of such conductive materials allows the conductive materials to function as antistatic agents, thereby more effectively suppressing or preventing the generation of static electricity on semiconductor chips during handling and pickup.

[0141] The tackifier is not particularly limited, but examples include rosin resin, terpene resin, coumarone resin, phenol resin, aliphatic petroleum resin, aromatic petroleum resin, aliphatic aromatic copolymer petroleum resin, etc., and one or more selected from these can be used in combination.

[0142] [3-3-7] Other conditions The thickness of the adhesive layer 13 is not particularly limited, but is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 30 μm or less.

[0143] This allows for a stronger bond between the sheet material 1 and the frame 11, and also enables more reliable and preferable separation of the sheet material 1 and the frame 11 after use of the semiconductor chip holding member 10, while preventing adhesive residue.

[0144] Such a semiconductor chip holding member 10 is used, for example, in the manufacturing of semiconductor packages to hold semiconductor chips during inspection and other processing or transportation.

[0145] In particular, in the manufacturing of semiconductor packages, by attaching a semiconductor chip to a sheet material 1 bonded to a frame 11, it can be suitably used as a holding member for holding a semiconductor chip during the lamination process of the package.

[0146] In particular, the semiconductor chip holding member 10 exhibits a suitable holding force for the semiconductor chip and, during pickup, possesses sufficient tackiness to exhibit suitable peelability between the holding layer 3 and the semiconductor chip.

[0147] After use of the semiconductor chip holding member 10, the adhesive layer 13 is cured by irradiating it with ultraviolet light, thereby reducing the adhesive adhesion of the adhesive layer 13 to the frame 11.

[0148] This causes delamination to occur between the adhesive layer 13 and the frame 11, allowing the sheet material 1 and the frame 11 to be suitably separated.

[0149] The detached frame 11 can be reused, for example. On the other hand, the detached sheet material 1 can be discarded, for example.

[0150] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto.

[0151] For example, the sheet material of the present invention may have a configuration other than those described above.

[0152] Furthermore, for example, the semiconductor chip holding member may have a configuration other than those described above.

[0153] Furthermore, the sheet material of the present invention is not limited to those used in the manufacture of semiconductor chip holding members as described above. [Examples]

[0154] The present invention will be described in detail below based on specific examples, but the present invention is not limited thereto. In the following examples, unless the temperature conditions are specified, the processes and measurements were performed at room temperature (25°C).

[0155] [4] Manufacturing of sheet materials

[0156] (Example 1) A sheet material with a thickness of 150 μm was manufactured by extruding a composition for forming a sheet material, which included an ethylene-vinyl acetate copolymer (Evaflex EV360, manufactured by Mitsui Dow Polychemicals) as a thermoplastic elastomer. The extruded resin was cooled on a mirror-finished roll to form a chip-holding surface.

[0157] In this example, the copolymerization ratio (%) of the ethylene-vinyl acetate copolymer used was ethylene / vinyl acetate = 75 / 25 in molar ratio.

[0158] (Example 2) A sheet material was manufactured in the same manner as in Example 1, except that a sheet material forming composition was used, which contained 80% by mass of ethylene-vinyl acetate copolymer ("Evaflex EV360" manufactured by Mitsui Dow Polychemicals) and 20% by mass of polypropylene ("Noblen FS2011DG3" manufactured by Sumitomo Chemical Co., Ltd.) as thermoplastic elastomers.

[0159] (Example 3) A sheet material was manufactured in the same manner as in Example 1, except that a sheet material forming composition containing ethylene-methyl methacrylate copolymer (EMMA) (Sumitomo Chemical Co., Ltd.'s "Aclift WH206-F") was used as the thermoplastic elastomer.

[0160] In this example, the copolymerization ratio (%) of the ethylene-methyl methacrylate copolymer used was ethylene / methyl methacrylate = 80 / 20 in molar ratio.

[0161] (Example 4) A sheet material was manufactured in the same manner as in Example 1, except that a sheet material forming composition containing an ethylene-butene copolymer ("Tafmer A4085S" manufactured by Mitsui Chemicals, Inc.) was used as the thermoplastic elastomer.

[0162] (Example 5) A sheet material was manufactured in the same manner as in Example 1, except that a sheet material forming composition was used, which contained 60% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer ("ToughTec H1221" manufactured by Asahi Kasei Corporation) and 40% by mass of polypropylene ("Noblen FS2011DG3" manufactured by Sumitomo Chemical Co., Ltd.) as the thermoplastic elastomer.

[0163] In this example, the copolymerization ratio (%) of the hydrogenated styrene-butadiene thermoplastic elastomer used was styrene / butadiene = 12 / 88 in molar ratio.

[0164] (Example 6) A sheet material was manufactured in the same manner as in Example 1, except that a sheet material forming composition was used, which contained 60% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer ("ToughTec H1221" manufactured by Asahi Kasei Corporation), 15% by mass of polypropylene ("Noblen FS2011DG3" manufactured by Sumitomo Chemical Co., Ltd.), and 25% by mass of a polyether-based antistatic agent ("Pelektron PVL" manufactured by Sanyo Chemical Industries, Ltd.) as the thermoplastic elastomer.

[0165] (Example 7) First, a 135 μm thick polypropylene (PP) film (Sumitomo Chemical's "Noblen FS2011DG3") was prepared as the base material.

[0166] Furthermore, a composition for forming a retaining layer was prepared by mixing 60% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer ("ToughTec H1221" manufactured by Asahi Kasei Corporation) and 40% by mass of polypropylene ("Noblen FS2011DG3" manufactured by Sumitomo Chemical Corporation).

[0167] A retaining layer-forming composition was applied to a substrate by an extrusion lamination method to form a retaining layer with a thickness of 15 μm, and a 150 μm sheet material was manufactured.

[0168] In the obtained sheet material, the thickness ratio of the retaining layer to the total thickness was 10%, and the thickness ratio of the base material was 90%.

[0169] (Example 8) The sheet material was manufactured in the same manner as in Example 7, except that the base material was a low-density polyethylene film (R300, manufactured by Ube Maruzen Polyethylene Co., Ltd.) with a thickness of 135 μm.

[0170] (Example 9) A sheet material was manufactured in the same manner as in Example 1, except that a sheet material forming composition was used, which contained 50% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer (Dynalon 1320P, manufactured by ENEOS Material Co., Ltd.) and 50% by mass of polypropylene (Noblen FS2011DG3, manufactured by Sumitomo Chemical Co., Ltd.) as the thermoplastic elastomer.

[0171] In this example, the copolymerization ratio (%) of the hydrogenated styrene-butadiene thermoplastic elastomer used was styrene / butadiene = 10 / 90 in molar ratio.

[0172] (Example 10) A sheet material was manufactured in the same manner as in Example 7, except that the retaining layer forming composition used contained 50% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer (Dynalon 1320P, manufactured by ENEOS Material Corporation) and 50% by mass of polypropylene (Noblen FS2011DG3, manufactured by Sumitomo Chemical Co., Ltd.).

[0173] (Comparative Example 1) A sheet material and a semiconductor chip holding member were manufactured in the same manner as in Example 1, except that a sheet material forming composition was used, which contained 50% by mass of ethylene-vinyl acetate copolymer ("Evaflex EV360" manufactured by Mitsui Dow Polychemicals) and 50% by mass of polypropylene ("Noblen FS2011DG3" manufactured by Sumitomo Chemical Co., Ltd.) as thermoplastic elastomers.

[0174] (Comparative Example 2) Except for using a sheet material forming composition containing a propylene-butene copolymer ("Toughmer XM7080" manufactured by Mitsui Chemicals, Inc.) as the thermoplastic elastomer, a sheet material and a semiconductor chip holding member were manufactured in the same manner as in Example 1.

[0175] (Comparative Example 3) A sheet material and a semiconductor chip holding member were manufactured in the same manner as in Example 1, except that a sheet material forming composition was used, which contained 20% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer ("ToughTec H1221" manufactured by Asahi Kasei Corporation) and 80% by mass of polypropylene ("Noblen FS2011DG3" manufactured by Sumitomo Chemical Co., Ltd.) as the thermoplastic elastomer.

[0176] (Comparative Example 4) A sheet material and a semiconductor chip holding member were manufactured in the same manner as in Example 7, except that the retaining layer forming composition used contained 20% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer ("ToughTec H1221" manufactured by Asahi Kasei Corporation) and 80% by mass of polypropylene ("Noblen FS2011DG3" manufactured by Sumitomo Chemical Co., Ltd.).

[0177] (Comparative Example 5) A sheet material and a semiconductor chip holding member were manufactured in the same manner as in Example 1, except that a sheet material forming composition was used, which contained 10% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer (Dynalon 1320P, manufactured by ENEOS Material Corporation) and 90% by mass of polypropylene (Noblen FS2011DG3, manufactured by Sumitomo Chemical Co., Ltd.) as the thermoplastic elastomer.

[0178] (Comparative Example 6) A sheet material and a semiconductor chip holding member were manufactured in the same manner as in Example 7, except that the retaining layer forming composition used contained 10% by mass of a hydrogenated styrene-butadiene thermoplastic elastomer (Dynalon 1320P, manufactured by ENEOS Material Corporation) and 90% by mass of polypropylene (Noblen FS2011DG3, manufactured by Sumitomo Chemical Co., Ltd.).

[0179] [5] Rating [5-1] Measurement of tack force of materials constituting the sheet material

[0180] The tack force was measured for the sheet materials of each of the above embodiments and comparative examples.

[0181] First, for each of the above-mentioned examples and comparative examples, a 5.0 mm diameter stainless steel probe was brought into contact with the sheet material from above using a tacking tester TAC-1000 manufactured by Resca, in accordance with JIS Z0237:2022. The speed at which the probe was brought into contact with the sheet material was set to 1 mm / sec, the contact load to 200 gf, the contact time to 1 second, and the probe temperature and plate temperature to 25°C. Subsequently, the probe was peeled upward at a peeling speed of 10 mm / sec, and the force required to peel it off was measured as the tack force.

[0182] The evaluation results of the tack force for the sheet materials of each of the above examples and comparative examples are shown in Tables 1 and 2.

[0183] In each of the above embodiments, the tack force when the material thickness was 150 μm was 10 kPa or more in all cases.

[0184] Furthermore, from the comparison between Example 1, Example 2, and Comparative Example 1, between Example 5 and Comparative Example 3, and between Example 9 and Comparative Example 5, it can be seen that the tack force can be adjusted by changing the content ratio of thermoplastic elastomer to polypropylene.

[0185] [5-2] Evaluation of the tack force of the sheet material as a whole For each of the above-mentioned examples and comparative examples, the tack force of the sheet material as a whole was measured. The tack force was measured using the same method as described above.

[0186] [5-3] Retention force of the silicon tip A ring-shaped frame was joined to the sheet material of each of the above embodiments and comparative examples to obtain a semiconductor chip holding member. A silicon chip measuring 6 mm square in plan view was placed on the sheet material constituting these semiconductor chip holding members and pressed down to hold it on the surface of the sheet material. Five silicon chips were held in each member.

[0187] Then, with the frame standing vertically, I lifted it by hand to a height of 100 cm above the desk and dropped it onto the desk to create an impact, repeating this action three times.

[0188] Additionally, vibrations were applied by holding the frame horizontally and shaking it from side to side by hand.

[0189] The subsequent condition of the semiconductor chip holder was visually observed and evaluated according to the following criteria.

[0190] ○: All silicon chips were retained. ×: One or more silicone chips have fallen off.

[0191] [5-4] Peelability (pickup) of silicon chips As described in [5-3] above, silicon chips measuring 6 mm square in plan view were placed on the sheet material constituting the semiconductor chip holding member according to each embodiment and comparative example and pressed down to hold them on the surface of the sheet material. Ten silicon chips were held in each case.

[0192] Then, the silicon tip was pushed up using four needles with a tip diameter of 100 μm, with a needle push-up amount of 500 μm.

[0193] Next, while maintaining the upward thrust of the silicon tip by the needle, the silicon tip was picked up by suction using a vacuum collet.

[0194] Through the above process, the pickup of silicon chips by adsorption was repeated 10 times for each of the sheet materials in the above-mentioned examples and comparative examples.

[0195] Then, for each of the above-mentioned examples and comparative examples, the success or failure of pickup by the adsorption of silicon chips (pickup capability) was observed and evaluated according to the following criteria.

[0196] ◎: We were able to pick out 10 silicon chips. ○: We were able to pick out 5 to 9 silicon chips. △: We were able to pick out silicon chips with a count of 1 to 4. ×: Not a single silicon chip was picked up.

[0197] [5-5] Sheet moldability Approximately 5 meters of sheet material produced in each of the above examples and comparative examples were wound onto a core layer with a diameter of approximately 10 cm to form a roll, which was then unwound and evaluated according to the following criteria.

[0198] ◎: It can be unwound without applying any force. ○: It can be unwound by applying force. ×: It cannot be wound up even when force is applied. These evaluation results are summarized in Tables 1 and 2.

[0199] [Table 1]

[0200] [Table 2]

[0201] By comparing Example 5 with Example 7, Example 9 with Example 10, Comparative Example 3 with Comparative Example 4, and Comparative Example 5 with Comparative Example 6, it can be seen that even when using the same retaining layer forming composition, it is possible to adjust the tack force of the entire sheet material to a suitable range by introducing a substrate.

[0202] By comparing Examples 6 to 8, it can be seen that even when using the same retaining layer-forming composition, the tack force of the entire sheet material can be adjusted to a suitable range by changing the type of substrate.

[0203] Furthermore, even if the tack force of the sheet material as a whole is relatively small, if the tack force of the part that holds the semiconductor chip, in other words, the material constituting the holding layer itself, is 10 kPa or more when the material has a thickness of 150 μm, the semiconductor chip can be held more effectively.

[0204] Furthermore, the semiconductor chip holding members of each of the above embodiments were able to suitably pick up the held semiconductor chips.

[0205] Furthermore, in each of the above embodiments, excellent sheet moldability was observed, and suitable sheet materials could be obtained. In particular, the hydrogenated ethylene-butadiene thermoplastic elastomers used in Examples 5 to 10 were difficult to form films on their own, but by mixing the ethylene-butadiene thermoplastic elastomers with polypropylene in a predetermined ratio, suitable films could be formed. [Explanation of Symbols]

[0206] 1 Sheet material 1a Part that holds the semiconductor chip 2 Base material 3 Retention layer 10 Semiconductor chip holding member 11 frames 12 Openings 13 Adhesive layer

Claims

1. A sheet material used to hold semiconductor chips, Composed of materials including thermoplastic elastomers, A sheet material characterized in that the tack force is 10 kPa or more when the material constituting the portion that holds the semiconductor chip has a thickness of 150 μm.

2. The sheet material according to claim 1, wherein the material constituting the portion that holds the semiconductor chip is composed of a material containing the thermoplastic elastomer and polyolefin.

3. The sheet material according to claim 2, wherein the material constituting the portion that holds the semiconductor chip is composed of a material including the thermoplastic elastomer and polypropylene.

4. The sheet material according to claim 2 or 3, wherein the content of the thermoplastic elastomer in the material constituting the portion that holds the semiconductor chip is X1 [mass%] and the content of the polyolefin is X2 [mass%], and the relationship 0.25 ≤ X1 / X2 is satisfied.

5. The sheet material according to claim 1 or 2, wherein the thermoplastic elastomer comprises at least one selected from the group consisting of ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, olefin copolymer, and hydrogenated styrene-based thermoplastic elastomer.

6. Substrate and The sheet material according to claim 1, further comprising a retaining layer provided on one side of the substrate and composed of a material containing at least the thermoplastic elastomer, for holding the semiconductor chip.

7. The sheet material according to claim 6, wherein the base material and the retaining layer contain the same type of material.

8. The sheet material according to claim 6 or 7, wherein the base material is made of a material containing polyolefin.

9. The sheet material according to claim 8, wherein the base material is made of a material containing polypropylene.

10. The sheet material according to claim 6 or 7, where T1 [μm] is the thickness of the retaining layer and T2 [μm] is the thickness of the substrate, and the relationship 0.03 ≤ T1 / T2 ≤ 30 is satisfied.

11. The aforementioned sheet material has a volume resistivity of 1.0 × 10 １５ The sheet material according to claim 1 or 2, wherein the density is less than or equal to (Ω・m).

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