Temporary adhesive film

Abstract

A temporary adhesive film, the temporary adhesive film comprising: a polyimide core film layer, the polyimide core film layer having a first surface and a second surface; the pressure-sensitive adhesive layer is arranged on the first surface of the polyimide core film layer; the epoxy thermosetting adhesive layer is arranged on the second surface of the polyimide core film layer; and a laser peelable elastomer layer, the laser peelable elastomer layer being disposed on the epoxy thermosetting adhesive layer. In a preferred embodiment, the laser peelable elastomer layer comprises carbon black.

Description

Technical Field

[0001] This disclosure relates to a temporary adhesive film comprising a polyimide core film layer, a pressure-sensitive adhesive layer, an epoxy thermosetting adhesive layer, and a laser-peelable elastomer layer. Background Technology

[0002] For wafer and panel-level semiconductor packaging processes, temporary adhesive films can be used. During the processing of the substrate to be processed, the temporary adhesive film is placed between the substrate and the carrier.

[0003] Thin-film substrates or flexible substrates can be used. Rigid substrates that are easily deformed at high temperatures can also be used. In the process of forming such thin-film substrates or using flexible substrates, or when using substrates that cannot withstand high temperatures and may deform, a process has been proposed to bond the substrate to a rigid carrier and then separate the substrate from the rigid carrier after the substrate processing is completed.

[0004] However, due to their flexible nature, and for example, the difficulty in transporting flexible substrates by rail equipment or robots, or incorporating them in boxes, it may be difficult to apply flexible substrates to existing manufacturing equipment.

[0005] Therefore, the flexible substrate is bonded to the rigid carrier before the element is formed, and the carrier supports the flexible substrate, while the element is formed on the flexible substrate, and after the element is formed on the substrate, the carrier detaches from the flexible substrate.

[0006] During the process of separating the substrate from the rigid carrier after substrate processing, the wafer or the substrate itself may be damaged, or the circuitry of the wafer and the components of the flexible substrate may be damaged.

[0007] To overcome this drawback, US 2022 / 0372339 A1 proposes an adhesive film comprising: a photothermal conversion layer containing a light absorber and a pyrolytic resin; a first adhesive layer disposed on the photothermal conversion layer; a base film layer (which is a PI film) disposed on the first adhesive layer; and a second adhesive layer disposed on the base film layer, wherein the first adhesive layer and the second adhesive layer contain a silicon-based adhesive. The photothermal conversion layer is a laser-exfoliable layer. After performing the desired semiconductor packaging process, the carrier and the processed substrate are separated by laser.

[0008] A drawback of the adhesive film described in US 2022 / 0372339 A1 is the difficulty in perfectly combining a robust PI film with a laser-peelable layer, which is a low-tack, high-molecular-weight elastomer. Even if the layers appear tightly bonded at room temperature, delamination can occur at the high temperatures required for semiconductor processing. When the adhesive film is applied to rapid heating processes or to large-area devices, layer delamination or voids between layers may occur.

[0009] US 2019 / 0330504 A1 discloses a method for temporarily bonding a workpiece and a substrate via an adhesive layer. An bonding step is performed, wherein the substrate and the workpiece are bonded via the adhesive layer. A processing step is performed, wherein the workpiece is processed. A peeling step is performed, wherein the adhesive layer is irradiated with a laser to separate the workpiece from the substrate. The adhesive layer is formed of an adhesive comprising a polymer and a light-absorbing material, wherein the polymer is a polyimide or an amyl acid / imide copolymer. Because the adhesive is applied to the workpiece or substrate as a liquid material, it is difficult to apply the adhesive to large-area panels. Since the bonding adhesive and the peeling adhesive are not separate components, a chemical cleaning step is essentially required to remove adhesive residues.

[0010] US 2013 / 0071658 A1 discloses an adhesive composition comprising an adhesive component and a tetrazolium compound. The adhesive composition can be used in adhesive tapes applied in methods for processing semiconductor wafers. Upon peeling, the tetrazolium releases nitrogen gas in response to UV light. Currently, thermal stability is a limitation.

[0011] As used herein, the terms “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably. The term “comprising” should also include the terms “consistently composed of” and “composed of.” Summary of the Invention

[0012] In a first aspect, this disclosure relates to a temporary adhesive film comprising:

[0013] A polyimide core film layer having a first surface and a second surface;

[0014] A pressure-sensitive adhesive layer is disposed on the first surface of the polyimide core film layer;

[0015] An epoxy thermosetting adhesive layer is disposed on the second surface of the polyimide core film layer; and

[0016] A laser-removable elastomer layer is disposed on the epoxy thermosetting adhesive layer.

[0017] The temporary adhesive film disclosed herein can maintain high adhesion during semiconductor processing and can easily detach the substrate fixed to the carrier from the carrier after the semiconductor processing.

[0018] The temporary adhesive film disclosed herein exhibits high thermal stability at the temperatures required for semiconductor packaging processes. Processing temperatures can reach up to 250°C, depending on the type of substrate being processed. The temporary adhesive film disclosed herein also demonstrates good chemical resistance, as well as excellent adhesion and peeling properties.

[0019] The temporary adhesive membrane disclosed in this paper has good resistance to delamination and a low risk of voids forming between layers.

[0020] The temporary adhesive film disclosed in this paper can achieve the peeling process from the carrier without damaging the substrate due to mechanical stress.

[0021] When the temporary adhesive film disclosed herein is used in semiconductor processing, no additional processes, such as post-curing and surface treatment, are required during the bonding process. After the semiconductor processing is completed, the temporary adhesive film can be removed by peeling without performing chemical cleaning and without leaving any residue.

[0022] The epoxy thermosetting adhesive layer exhibits excellent adhesion strength to both the laser-peelable elastomer layer and the polyimide core film layer. Even before the epoxy thermosetting adhesive has cured, the epoxy thermosetting adhesive layer maintains sufficient adhesion to both the laser-peelable elastomer layer and the polyimide core film layer.

[0023] When the temporary adhesive film disclosed herein is used in high-temperature processes such as semiconductor processing, it does not experience shrinkage or expansion issues.

[0024] The temporary adhesive film disclosed herein can be used in large-area semiconductor packaging processes, such as large-area fan-out panel-level packaging (FOPLP). The temporary adhesive film disclosed herein can also be used in through-silicon via (TSV) semiconductor processing processes with high process temperatures. Detailed Implementation

[0025] There is still a need for temporary adhesive films that can maintain high adhesion during semiconductor processing, allow easy detachment of the substrate from the carrier after semiconductor processing, and possess high thermal stability, chemical resistance, and good adhesion and peeling properties.

[0026] This article discloses a temporary adhesive membrane, which includes:

[0027] A polyimide core film layer having a first surface and a second surface;

[0028] A pressure-sensitive adhesive layer is disposed on the first surface of the polyimide core film layer;

[0029] An epoxy thermosetting adhesive layer is disposed on the second surface of the polyimide core film layer; and

[0030] A laser-removable elastomer layer is disposed on the epoxy thermosetting adhesive layer.

[0031] A "temporary adhesive film" is an adhesive film that is temporarily used in processes such as semiconductor packaging and is removed after the process is completed. Temporary adhesive films can also be referred to as temporary bond and release (TBDB) films.

[0032] During the processing of the substrate to be processed, a temporary adhesive film is placed between the substrate and the carrier. The process for processing the substrate can be a semiconductor packaging process.

[0033] The temporary adhesive film disclosed herein is a film-type film, formed by forming a pressure-sensitive adhesive layer and an epoxy thermosetting adhesive layer on a first and second surface of a rigid polyimide core film layer, respectively, and by bringing the epoxy thermosetting adhesive layer and the laser-peelable elastomer layer into contact with each other. That is, this disclosure forms a film with a multi-layered structure as an adhesive film, rather than directly coating a carrier and a substrate to be treated with the liquid material. In subsequent processing of the substrate, the pressure-sensitive adhesive layer is bonded to the substrate, and the laser-peelable elastomer layer is bonded to the rigid carrier.

[0034] The polyimide core film layer has a first surface and a second surface. The polyimide core film layer supports a pressure-sensitive adhesive layer disposed on the first surface and an epoxy thermosetting adhesive layer disposed on the second surface. The polyimide core film layer is a rigid material film.

[0035] The polyimide core film layer allows for easy removal of pressure-sensitive adhesives and epoxy thermosetting adhesives remaining on the substrate after the substrate processing is completed, via laser projection separation of the laser-peelable elastomer layer.

[0036] The polyimide core film layer exhibits excellent heat resistance and a low coefficient of thermal expansion (CTE). Generally speaking, the polyimide core film layer has a CTE of less than or equal to approximately 25 × 10⁻⁶. -6 K -1 The CTE value.

[0037] The thickness of the polyimide core film can range from 25µm to 100µm, typically from 40µm to 80µm, and more generally from 50µm to 75µm. If the thickness of the polyimide core film is less than about 25µm, the core film is so thin that the coating capability during the coating process is reduced and the thickness is difficult to adjust. Furthermore, if the thickness of the polyimide core film exceeds about 100µm, the total thickness of the temporary adhesive film becomes thicker, and the temporary adhesive film becomes rigid, resulting in reduced lamination or adhesion properties to the substrate and carrier.

[0038] A pressure-sensitive adhesive layer is disposed on the first surface of the polyimide core film layer. The pressure-sensitive adhesive layer is used to fix the substrate. The pressure-sensitive adhesive in the pressure-sensitive adhesive layer may contain a siloxane. The siloxane may include a free radical-cured siloxane adhesive or an addition-cured siloxane adhesive.

[0039] Siloxane-based pressure-sensitive adhesive layers exhibit excellent stability at high temperatures and superior heat resistance. Furthermore, siloxane-based pressure-sensitive adhesive layers can be softer than adhesive layers made of other materials, such as acrylic adhesive layers, resulting in excellent lamination performance when bonding rigid materials (such as substrates and carriers).

[0040] Siloxane-based pressure-sensitive adhesive layers allow for the removal of temporary adhesive films at temperatures above or equal to 150°C with a small force of approximately 40 gf / 25 mm without leaving residue on the device (such as a substrate). Furthermore, the adhesive film can be removed at temperatures from 60°C to 100°C with a force of approximately 200 gf / 25 mm to 300 gf / 25 mm. When acrylic adhesives are used instead of siloxane-based pressure-sensitive adhesive layers, the cohesive strength is low at high temperatures, making removal in this manner impossible. Acrylic adhesives leave residue at high temperatures, and the adhesive layer can melt or be torn.

[0041] An epoxy thermosetting adhesive layer is disposed on the second surface of the polyimide core film layer. The epoxy thermosetting adhesive layer is used to bond the polyimide core film layer and the laser-peelable elastomer layer to each other. If the epoxy thermosetting adhesive layer is omitted and the laser-peelable elastomer layer and the polyimide core film layer are directly bonded to each other, there is a problem that detachment can occur at temperatures above or equal to approximately 230°C.

[0042] The epoxy thermosetting adhesive layer enhances the lamination performance of the laser-peelable elastomer layer and the polyimide core film layer, and increases their adhesion at high temperatures, thereby enabling high-temperature processes. In other words, the epoxy thermosetting adhesive layer is the layer that contacts the laser-peelable elastomer layer and exhibits excellent adhesion. When using a silicone adhesive instead of the epoxy thermosetting adhesive, there is a risk of delamination and voids between the layers (i.e., between the silicone adhesive and the laser-peelable elastomer layer) when using a temporary adhesive film during rapid heating or when applying the temporary adhesive film to large-area devices with high stress.

[0043] After the substrate and carrier are separated from each other by a split laser-exfoliable elastomer layer, a substrate bonded to a pressure-sensitive adhesive layer is obtained. Therefore, the pressure-sensitive adhesive layer should be easily detachable from the substrate by means of release. The pressure-sensitive adhesive layer is a film-type layer formed on a polyimide core film, rather than a photocurable adhesive directly coated onto the substrate.

[0044] The epoxy thermosetting adhesive layer comprises an epoxy thermosetting adhesive. The epoxy thermosetting adhesive comprises an epoxy resin, a curing agent, and a binder.

[0045] Epoxy thermosetting adhesives typically also contain solvents to enable coating of the epoxy thermosetting adhesive onto the second surface of the polyimide core film layer. The solvent can be an organic solvent, typically a polar organic solvent. The solvent can be selected from the group consisting of isopropanol, methyl ethyl ketone, ethyl acetate, ethanol, methanol, acetone, and combinations thereof. Trace amounts of aromatic organic solvents such as toluene may be added to polar solvents such as methyl ethyl ketone and ethyl acetate. In some embodiments, the solvent does not contain aromatic organic solvents. The boiling point of the solvent can be above 50°C and below 100°C. Based on the total weight of the epoxy thermosetting adhesive, the solids content of the epoxy thermosetting adhesive, i.e., the content of epoxy resin, curing agent, binder, and other solid components (if present), can be from 10% by weight to 25% by weight.

[0046] Based on the total solids content of the epoxy thermosetting adhesive, the epoxy thermosetting adhesive may contain up to 55% by weight of binder.

[0047] Based on the total solids content of the epoxy thermosetting adhesive, the epoxy thermosetting adhesive may contain at least 35% by weight, and typically at least 40% by weight, of adhesive.

[0048] Typically, epoxy thermosetting adhesives contain about 40% to about 50% by weight of curing agent, based on the sum of the weight of epoxy resin and curing agent.

[0049] The weight ratio of the total amount of epoxy resin and hardener contained in an epoxy thermosetting adhesive to the amount of adhesive, i.e., the ratio (weight of epoxy resin plus weight of hardener):(weight of adhesive), can be 1:9 to 9:1, typically 2:8 to 8:2, and more generally 4:6 to 6:4. When the weight ratio is too high, i.e., when the amount of epoxy resin and hardener is too large and the amount of adhesive is too small, deformation may occur when using temporary adhesive films at high temperatures. Conversely, when the weight ratio is too low, i.e., when the amount of epoxy resin and hardener is too small and the amount of adhesive is too high, the heat resistance will be insufficient. The weight ratio of the total amount of epoxy resin and hardener contained in an epoxy thermosetting adhesive to the amount of adhesive, i.e., the ratio (weight of epoxy resin plus weight of hardener):(weight of adhesive), can also be referred to as the "epoxy ratio".

[0050] The epoxy resin contained in the epoxy thermosetting adhesive may be selected from the group consisting of: phenolic epoxy resin, cresol phenolic epoxy resin, bisphenol A phenolic epoxy resin, dicyclopentadiene (DCPD) phenolic epoxy resin, bisphenol F (BPF) epoxy resin, bisphenol A (BPA) epoxy resin, and combinations thereof.

[0051] Suitable epoxy resins are: YDPN-631, YDPN-638, YDPN-641, YDCN-500-4P, YDCN-500-8P, YDCN-500-80P, YDCN-500-90P, YD-128, YD-170, and YD-8128, purchased from Kukdo Chemical, South Korea; Epicon N740, Epicon N680, and Epicon N865, purchased from DIC Corporation, Japan; and KEB-3165, KED-3170, KEB-3180, KE-8120, KF-8100, and NK's XD-1000. 2L, XD-1000, XD-1000H, NC-3000 and NC-3000H were purchased from Kolon Industries, South Korea.

[0052] Epoxy resins included in epoxy thermosetting adhesives may comprise bifunctional epoxy resins having two terminal epoxide functional groups, i.e., having one epoxide functional group at each end of the epoxy resin molecule. Examples of bifunctional epoxy resins are bisphenol F (BPF) epoxy resin and bisphenol A (BPA) epoxy resin.

[0053] Epoxy resins included in epoxy thermosetting adhesives may include multifunctional epoxy resins. As used herein, a “multifunctional epoxy resin” is an epoxy resin molecule containing at least three epoxide functional groups, namely one epoxide functional group at each end of the epoxy resin molecule and at least one additional epoxy functional group in the epoxy resin molecule. The term “epoxide group” refers to a functional and highly reactive group consisting of two carbon atoms and one oxygen atom arranged in a ring, also known as an ethylene oxide group. Multifunctional epoxy resins may contain three, four, or five (or more) epoxide functional groups in the epoxy resin molecule. Combinations of epoxy resin molecules with different numbers of epoxy functional groups are also possible. Generally, multifunctional epoxy resins contain three epoxide groups in the epoxy resin molecule. The epoxy resin contained in the epoxy thermosetting adhesive may also include combinations of several difunctional and / or polyfunctional epoxy resins, such as a combination of a difunctional epoxy resin and a polyfunctional epoxy resin containing three epoxide groups, or a combination of a polyfunctional epoxy resin containing three epoxide groups and a polyfunctional epoxy resin containing four epoxide groups.

[0054] By curing multifunctional epoxy resins, highly cross-linked polymers are formed from epoxy resin molecules due to their high functionality. Examples of multifunctional epoxy resins are phenolic epoxy resins, such as phenolic epoxy resins, cresol epoxy resins, bisphenol A epoxy resins, and dicyclopentadiene (DCPD) epoxy resins.

[0055] To avoid being bound by theory, the use of multifunctional epoxy resins helps improve the coating and adhesion properties of epoxy thermosetting adhesives and reduces film shrinkage at high temperatures after coating.

[0056] The softening point of epoxy resins can be up to 70°C, but is typically up to 65°C. Using epoxy resins with a softening point of up to 70°C helps to provide high adhesion at room temperature. If the resin has a softening point of up to 70°C, it provides high adhesion at room temperature and excellent adhesion to the polyimide core film layer.

[0057] The softening point of epoxy resin can be considered as the temperature at which the solid phase of the epoxy resin begins to become viscous. The softening point of epoxy resin can be measured using a VST (Vicat softening temperature) device. As the temperature of the epoxy resin sample increases, the resin softens slowly, and this softening occurs when the penetration tip reaches 1 mm. 2 The temperature at which a flat needle of approximately 1 mm is cut can be defined as the softening point.

[0058] For bifunctional epoxy resins, i.e., epoxy resins containing only two terminal epoxide functional groups, liquid epoxy resins with softening points below room temperature (23°C) can be used. For bifunctional epoxy resins, the curing profile should be set slowly to ensure uniform surface roughness of the cured epoxy thermosetting adhesive.

[0059] The curing agents used in this paper are selected from the group consisting of amine-based curing agents, phenol-based curing agents, acid anhydride curing agents, peroxide curing agents, imidazole curing agents, and combinations thereof. Typically, the curing agent is a phenol-based curing agent. In addition to curing agents, curing catalysts such as imidazole curing catalysts can also be used. For example, phenol can be used as a curing agent, and a small amount of imidazole can be added as a curing catalyst.

[0060] Suitable curing agents include dicyandiamide (DICY), phenolic resins, xylok-type phenolic resins, imidazoles, organic peroxides, and combinations thereof. Generally, phenolic resins, xylok-type phenolic resins, imidazoles, and combinations thereof can be used. For example, PN-23, MY-24, and AH-154 were purchased from Ajinomoto, Japan; MEH-7800SS, MEH-78004S, and MEH-7800S were purchased from Meiwa Corporation, Japan; KPH-F3060, KPH-F3065, KPH-F3075, KPH-F2001, KPH-F2002, and KPH-F2003 were purchased from Kolon Industries, South Korea; 2PHZ-PW, 2PZ-CN, 2PZ-OK, 2MA-OK, 2E4MZ, and 2E4MZ-CN were purchased from Shikoku Chemical Corporation, Japan; and biphenyl peroxide was purchased from Hansol Chemical, South Korea.

[0061] The curing initiation point of the epoxy thermosetting adhesive used in this article may be at least 70°C and at most 180°C, or at least 140°C and at most 160°C. For example, the curing initiation point may be 70°C, 80°C, 100°C, 120°C, 140°C, or 170°C.

[0062] The curing initiation point can be measured using differential scanning calorimetry (DSC).

[0063] The curing peak temperature can be at least 80°C and at most 170°C.

[0064] If the starting point is below 120°C, the temporary adhesive film may shrink due to rapid curing, and the surface roughness of the coating may deteriorate during application and drying on the polyimide core film layer. On the other hand, if the starting point is above 180°C, curing may not be achieved as expected, which could lead to deterioration of other properties such as heat resistance and adhesion. Furthermore, if the peak point is too high, sufficient curing may not be achieved as required, which could result in reduced heat resistance and adhesive strength.

[0065] The adhesive included in the epoxy thermosetting adhesive may contain at least one of a rubber-based elastomer and an acrylic elastomer.

[0066] Acrylic elastomers may comprise acrylic polymers made by polymerizing at least one acrylic monomer selected from the group consisting of: ethyl acrylate, butyl acrylate, glycidyl methacrylate, acrylic acid, acrylonitrile, and combinations thereof. For example, acrylic elastomers may comprise combinations of ethyl acrylate, butyl acrylate, and glycidyl methacrylate. Suitable acrylic elastomers are, for example: SG-80H, SG-P3, SG-708-6, and WS-023, purchased from Nagase & Co., Ltd., Japan; CS-200, purchased from Negami Chemical Industrial Co., Ltd., Japan; and KNB-35N, KNB-35H, KNB-40M, and KNB-40H, purchased from Kumho Petrochemical Co., Ltd., South Korea.

[0067] The molecular weight (Mw) of acrylic polymers can range from 300,000 to 1.2 million, typically from 500,000 to 1 million. When the molecular weight is too low, the heat resistance is insufficient, while when the molecular weight is too high, it is difficult to apply and manufacture films.

[0068] Acrylic polymers contained in acrylic elastomers may contain polar functional groups, meaning that the acrylic polymer contains polar functional groups in its polymer backbone. Polar functional groups may be selected from the group consisting of: nitrile groups, carboxyl groups, hydroxyl groups, glycidyl groups, amine groups, and combinations thereof.

[0069] Generally speaking, the polar functional groups are carboxyl groups and / or hydroxyl groups, and acrylic polymers may contain at least 1 mg KOH / g of polymer polar functional groups.

[0070] More generally, the polar functional group is a carboxyl group and / or a hydroxyl group, and the acrylic polymer contains polar functional groups ranging from 1 mg KOH / g polymer to 25 mg KOH / g polymer. The polar functional group can be a carboxyl group and / or a hydroxyl group, and the acrylic polymer can contain polar functional groups ranging from 10 mg KOH / g polymer to 25 mg KOH / g polymer, or from 15 mg KOH / g polymer to 25 mg KOH / g polymer.

[0071] The amount of polar functional groups can be measured by acid-base titration.

[0072] When the amount of polar functional groups in acrylic polymers is less than 1 mg KOH / g polymer, the adhesion or tackiness of the polyimide core film can be significantly reduced.

[0073] The adhesive contained in the epoxy thermosetting adhesive may have a glass transition temperature of at least -20°C and at most 60°C.

[0074] If the glass transition temperature is above 60°C, adhesion and coating properties decrease, while if it is below -20°C, problems arise in terms of thermal stability and film formation.

[0075] The thickness of the epoxy thermosetting adhesive layer can range from 10µm to 45µm. If the thickness is less than 10µm, the adhesion may be reduced, while if the thickness is greater than 45µm, the surface uniformity will decrease during coating and voids may appear when the solvent dries. Generally, the thickness is in the range of 20µm to 40µm.

[0076] The thickness of the pressure-sensitive adhesive layer can range from 20µm to 100µm, typically from 30µm to 75µm, and more generally from 50µm to 75µm. Higher thickness of the pressure-sensitive adhesive layer can benefit thermal stability. The thicker the pressure-sensitive adhesive layer, the higher the adhesion. If the thickness is less than 20µm, the adhesion is too low and may cause delamination during high-temperature processes, and when removed, the resin may tear and leave residue.

[0077] The temporary adhesive film disclosed herein includes a laser-peelable elastomer layer disposed on an epoxy thermosetting adhesive layer.

[0078] When radiant energy such as laser energy is projected, the laser-strippable elastomer layer is split into layers such that the substrate can be separated from the carrier without damaging the substrate or the components or circuits on the substrate.

[0079] The laser-exfoliable elastomer layer may contain a light absorber and a pyrolytic resin. Radiation energy applied to the laser-exfoliable elastomer layer in the form of a laser is absorbed by the light absorber and converted into heat energy. The generated heat energy rapidly increases the temperature of the laser-exfoliable elastomer layer, reaching the pyrolysis temperature of the pyrolytic resin (organic component) within the layer, thus inducing pyrolysis of the resin. The gas produced by pyrolysis forms an opening (such as a space) within the laser-exfoliable elastomer layer, dividing it into two parts, and thus separating the carrier and the substrate.

[0080] Light absorbers can absorb radiant energy and convert it into heat energy. Furthermore, they act as light blockers and prevent damage to the substrate from lasers and other sources.

[0081] Although the light absorber varies depending on the wavelength of the laser, examples of usable light absorbers include carbon black, graphite powder, ultrafine metal powders (such as iron, aluminum, copper, nickel, cobalt, manganese, chromium, zinc, and tellurium), metal oxide powders (such as black titanium dioxide), and dyes and pigments (such as metal complexes based on aromatic diamines, metal complexes based on aliphatic diamines, metal complexes based on aromatic dithiols, metal complexes based on hydroxybenzenethiophenols, compounds based on squaric acid cyanine, cyanine-based dyes, methylene-based dyes, naphthoquinone-based dyes, and anthraquinone-based dyes). The light absorber can be in the form of a film, including vapor-deposited metal films.

[0082] Carbon black is particularly useful among light absorbers because it significantly reduces the force required to separate the substrate from the carrier after projection and accelerates the separation process.

[0083] The particle size of the light absorber in the laser-exfoliable elastomer layer can be from about 20 nm to about 2000 nm, typically from about 50 nm to about 1000 nm, and more generally from about 100 nm to about 350 nm.

[0084] If the particle size of the light absorber is less than about 20 nm, it may be difficult to disperse, and a large amount of light absorber may not be loaded because the surface area increases with smaller particle size, and there is a limitation on the loading amount. Furthermore, if the particle size of the light absorber exceeds about 2000 nm, it can reduce laser blocking performance and the ability to laser-splitting laser-exfoliable elastomer layers. In addition, increasing the particle size of the light absorber can reduce film-forming ability and dispersion stability after dispersion.

[0085] Based on the total weight of the laser-peelable elastomer layer, the content of the light absorber in the laser-peelable elastomer layer can be from about 5% to about 80% by weight, typically from about 10% to about 60% by weight, and more generally, based on the total weight of the laser-peelable elastomer layer, it can be from about 20% to about 50% by weight.

[0086] If the content of the light absorber is less than about 5% by weight, it is difficult to separate by laser. In addition, if the content of the light absorber exceeds about 80% by weight, after the laser-separated elastomer layer is separated by laser, a portion of the laser-separated laser-separated elastomer layer remains on the surface of the epoxy thermosetting adhesive layer, and in this case, the adhesion may be very low due to the high carbon content.

[0087] In this case, there are problems in the process of removing the epoxy thermosetting adhesive layer, polyimide core film layer, and pressure-sensitive adhesive layer using the removal tape. This portion of the laser-exfoliable elastomer layer does not adhere well to the removal tape and is difficult to remove. Furthermore, as the content of the light absorber increases, the surface adhesion of the laser-exfoliable elastomer layer decreases, making it difficult to laminate onto the carrier, and the dispersion of the light absorber is uneven.

[0088] The pyrolytic resin in the laser-exfoliable elastomer layer may include acrylic resins. Acrylic resins are typically acrylic elastomers. Generally, acrylic resins contain monomers selected from the group consisting of methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), ethyl acrylate (EA), butyl acrylate (BA), acrylonitrile (AN), and combinations thereof. Generally, the monomers may be selected from three or more combinations of methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), ethyl acrylate (EA), butyl acrylate (BA), and acrylonitrile (AN). Such acrylic resins may have suitable molecular weight, Tg, heat resistance, and functional groups.

[0089] Based on the total weight of the laser-peelable elastomer layer, the content of acrylic resin can be from about 5% to about 80% by weight, typically from about 15% to about 60% by weight, and more generally, based on the total weight of the laser-peelable elastomer layer, it can be from about 40% to about 60% by weight.

[0090] If the acrylic resin content is less than about 5% by weight, the film-forming ability is reduced and it is difficult to adjust the thickness of the laser-released elastomer layer, and it is also difficult to laminate it onto the carrier because the surface adhesion of the laser-released elastomer layer is very low. Furthermore, if the acrylic resin content exceeds about 80% by weight, a large physical force is required when the laser-released elastomer layer is split after laser projection, and it may be difficult to separate the substrate and carrier, potentially damaging the substrate and any components or circuits formed on it.

[0091] The pyrolytic resin in the laser-releaseable elastomer layer has -COOH or -OH functional groups. Generally, pyrolytic resins include acrylic resins with -COOH or -OH functional groups. Laser-releaseable elastomer layers containing pyrolytic resins with -COOH or -OH functional groups are not pressure-sensitive adhesives. The presence of -COOH or -OH functional groups in the laser-releaseable elastomer layer allows it to bond to a carrier via hydrogen bonding, and for example, to silanol groups on the glass surface of a carrier formed of glass. In this case, hydrogen bonding provides initial adhesion for bonding the laser-releaseable elastomer layer to the carrier, and the adhesion between the laser-releaseable elastomer layer and the carrier is greatly increased due to the heat generated during the subsequent bonding process.

[0092] The -COOH or -OH functional groups can have an acid value greater than or equal to about 1 mg KOH / g, and typically greater than or equal to about 5 mg KOH / g. The lamination performance of laser-exfoliable elastomer layers is based on the -COOH or -OH functional groups, and if the acid value of the -COOH or -OH functional groups is less than about 1 mg KOH / g, the lamination performance decreases. The upper limit of the acid value of -COOH or -OH is not a problem. However, due to the chemical structure, the acid value can typically be from about 1 mg KOH / g to about 50 mg KOH / g, more generally from about 1 mg KOH / g to about 30 mg KOH / g, and most generally from about 10 mg KOH / g to about 20 mg KOH / g.

[0093] The laser-peelable elastomer layer may also contain inorganic fillers. After the laser-peelable elastomer layer is split due to the opening layer formed by the pyrolysis of the resin, the inorganic fillers prevent the laser-peelable elastomer layer from re-bonding. Therefore, when separating the laser-peelable elastomer layer by projecting a laser after processing the substrate, the physical force required to separate the substrate and carrier can be further reduced.

[0094] Inorganic fillers can be selected from the group consisting of SiO2, Al2O3, TiO2, and combinations thereof. Generally, inorganic fillers may contain at least one of titanium dioxide or silicon dioxide. Specifically, in the case of TiO2, an additional light-blocking effect exists on the substrate.

[0095] The inorganic filler may contain at least one of alumina-coated titanium dioxide or silicon dioxide.

[0096] The particle size of the inorganic filler in the laser-exfoliable elastomer layer can be from about 20 nm to about 2000 nm, typically from about 50 nm to about 1000 nm, and more generally from about 100 nm to about 350 nm. If the particle size of the inorganic filler is less than about 20 nm, it is not easy to disperse the inorganic filler when preparing the film, and there is a limitation on the amount that can be loaded. Furthermore, if the particle size of the inorganic filler exceeds about 2000 nm, the film-forming ability is reduced and the dispersion persistence after dispersion can be reduced.

[0097] Based on the total weight of the laser-exfoliable elastomer layer, the content of inorganic filler in the laser-exfoliable elastomer layer can be from about 4% to about 60% by weight, typically from about 5% to about 50% by weight, and more generally, from about 5% to about 30% by weight based on the total weight of the laser-exfoliable elastomer layer. If the content of inorganic filler is less than about 4% by weight, the adhesion on the separated surface after the laser projection separation process is strong, and the laser-exfoliable elastomer layer can re-bond over time. Furthermore, if the content of inorganic filler exceeds about 60% by weight, the adhesion of the laser-exfoliable elastomer layer is very low, it is difficult to laminate onto a carrier, and the film-forming ability is reduced and the dispersion is uneven.

[0098] The laser-exfoliable elastomer layer may also contain a dispersant. Based on the total weight of the laser-exfoliable elastomer layer, the dispersant content can be from about 0.1 wt% to about 10 wt%, typically from about 0.1 wt% to about 7 wt%, and more generally, from about 0.1 wt% to about 5 wt% based on the total weight of the laser-exfoliable elastomer layer. If the dispersant content is less than about 0.1 wt%, the dispersibility of the light absorber and inorganic filler in the laser-exfoliable elastomer layer may decrease, and the dispersion persistence after dispersion may also decrease. Furthermore, if the dispersant content exceeds about 10 wt%, the heat resistance of the laser-exfoliable elastomer layer may decrease.

[0099] The thickness of the laser-peelable elastomer layer can range from about 1 µm to about 30 µm, typically from about 3 µm to about 20 µm, and more generally from about 5 µm to about 15 µm. If the thickness of the laser-peelable elastomer layer is less than about 1 µm, the upper adhesive layer can directly affect the material, and the laser blocking performance may be reduced due to the light absorber. Furthermore, if the thickness of the laser-peelable elastomer layer exceeds about 30 µm, a significant amount of adhesive residue may remain on the carrier after laser projection.

[0100] Laser-exfoliable elastomer layers can exhibit adhesion relative to a carrier ranging from 150 gf / 25 mm to 3200 gf / 25 mm.

[0101] The temporary adhesive film disclosed herein may also include a first liner disposed on the pressure-sensitive adhesive layer opposite to the polyimide core film layer.

[0102] The temporary adhesive film disclosed herein may also include a second liner disposed on the laser-peelable elastomer layer opposite to the epoxy thermosetting adhesive layer.

[0103] The first and second pads support and protect the laser-peelable elastomer layer and the pressure-sensitive adhesive layer, respectively. The first and second pads can be removed when a temporary adhesive film is used.

[0104] The first and second liners can be siloxane-coated or fluorinated polyethylene terephthalate (PET), but are not limited thereto, and any material that supports and protects the adhesive film can be used.

[0105] The temporary adhesive film disclosed herein can be prepared by a method including the following steps.

[0106] A polyimide core film layer is provided, the polyimide core film layer having a first surface and a second surface;

[0107] Casting lasers can peel off the elastomer layer;

[0108] A pressure-sensitive adhesive layer is coated on the first surface of the polyimide core film layer;

[0109] An epoxy thermosetting adhesive layer is coated on the second surface of the polyimide core film layer;

[0110] The laser-peelable elastomer layer is laminated onto the epoxy thermosetting adhesive layer to obtain the temporary adhesive film.

[0111] All the specific details of the polyimide core film layer, laser-peelable elastomer layer, pressure-sensitive adhesive layer, and epoxy thermosetting adhesive layer described above in the context of temporary adhesive films also apply here.

[0112] All casting, coating, and lamination steps in the method for preparing a temporary adhesive film can be performed as a continuous roll-to-roll process. However, the method for preparing a temporary adhesive film disclosed herein is not limited to a continuous roll-to-roll process, and any method that can laminate multiple adhesive film layers can be applied.

[0113] Coating a pressure-sensitive adhesive layer on the first surface of the polyimide core film layer includes applying a pressure-sensitive adhesive to the first surface of the polyimide core film layer and drying it.

[0114] Applying an epoxy thermosetting adhesive layer to the second surface of a polyimide core film layer involves mixing epoxy resin, a curing agent, and an adhesive, and applying the resulting adhesive mixture as a layer to the second surface of the polyimide core film layer. After applying the adhesive mixture layer to the second surface of the polyimide core film layer, the adhesive mixture layer is dried and cured at a temperature of 120°C to 170°C, typically at about 145°C. After curing and drying the applied adhesive, a laser-releaseable elastomer layer is laminated onto it.

[0115] The laser-releasable elastomer layer is laminated onto the epoxy thermosetting adhesive layer by using heated rollers at a temperature of 50°C to 100°C, typically around 80°C.

[0116] Before applying the pressure-sensitive adhesive layer to the first surface, the first surface of the polyimide core film layer can be treated with a primer; that is, a primer layer can be applied to the first surface of the polyimide core film layer. Primer treatment increases the adhesion of the polyimide core film layer to the pressure-sensitive adhesive layer.

[0117] The primer layer may contain an addition-curing resin, a platinum catalyst, and a crosslinking agent. The primer layer can be cured at a temperature of about 140°C or higher. The thickness of the primer layer can be from 50 nm to 500 nm, typically from 50 nm to 300 nm, and more generally from 100 nm to 300 nm.

[0118] The second surface of the polyimide core film layer can be surface-treated, for example, by corona treatment, atmospheric plasma treatment, or wet treatment using an aqueous KOH solution (0.1M to 3M). Combinations of these surface treatments can also be applied. Surface treatment can increase the adhesion between the polyimide core film layer and the epoxy thermosetting adhesive layer.

[0119] The method for preparing the temporary adhesive film disclosed in this article may also include:

[0120] This makes the temporary adhesive film chemically stable.

[0121] After laminating the laser-release elastomer layer onto the epoxy thermosetting adhesive layer, a step is performed to chemically stabilize the temporary adhesive film. This temporary stabilization step chemically stabilizes all four layers of the four-layer film. The temporary stabilization step can be performed by aging at 45°C for a certain period of time. Typically, this step lasts approximately 12 to 24 hours.

[0122] The chemical stabilization step of the temporary adhesive film can help prevent cracking that may occur due to shrinkage caused by rapid curing when the temporary adhesive film is introduced into a process involving rapid heating. Furthermore, for pressure-sensitive adhesive layers, the chemical stabilization step of the temporary adhesive film can help prevent potentially undesirable residues during high-temperature processes.

[0123] After a pressure-sensitive adhesive layer is coated on the first surface of the polyimide core film layer, the pressure-sensitive adhesive layer may be protected by a liner disposed opposite the polyimide core film layer on the pressure-sensitive adhesive layer. The liner may be, for example, a PET liner. The PET liner may be silicone-coated or fluorinated.

[0124] After the laser-peelable elastomer layer is laminated onto the epoxy thermosetting adhesive layer, the laser-peelable elastomer layer can be protected by a gasket disposed opposite the epoxy thermosetting adhesive layer on the laser-peelable elastomer layer. The gasket can be, for example, a PET gasket. The PET gasket can be silicone-coated or fluorinated. Example Test methods Observation of defects that occurred during coating

[0125] The coating performance of the epoxy thermosetting adhesive on the polyimide core film is evaluated by visually inspecting for problems and defects that occur during the coating process. Adhesion test

[0126] The adhesion / tack of the epoxy thermosetting adhesive layer to the laser-peelable elastomer layer and polyimide core film layer was tested. Adhesion was verified by a 180° peel test. First, the laser-peelable elastomer layer side of the prepared temporary adhesive film sample was laminated to a glass specimen at 70°C. Then, the sample was clamped and forcibly peeled off, and the fracture trend of the temporary adhesive film was observed. For all samples, delamination occurred at the interface between the epoxy thermosetting adhesive layer and the polyimide core film layer. Adhesion was evaluated before and after curing. Thermal stability test

[0127] Thermal stability was evaluated using a 230°C oven test and a 180°C hot plate test. After bonding two glass slides with a prepared temporary adhesive film sample, delamination or voids generated during the high-temperature process were visually observed. The 230°C oven test is an evaluation method simulating the curing process of the passivation layer during redistribution layer (RDL) accumulation. RDL is a semiconductor packaging process. The 180°C hot plate test is an evaluation method simulating the metal deposition process of the fan-out process during RDL accumulation.

[0128] For the 230°C oven test (glass-wafer bonding), samples were prepared by bonding a glass carrier (a 12-inch diameter disk) and an EMC (epoxy molding compound) molded wafer (a 12-inch diameter circular wafer (disk)) to a temporary adhesive film sample. The glass carrier was bonded to the laser-peelable elastomer layer side of the temporary adhesive film, and the EMC molded wafer was bonded to the pressure-sensitive adhesive layer side of the temporary adhesive film. The prepared samples (bonded to the glass carrier and the temporary adhesive film of the EMC molded wafer) were placed in an oven at room temperature (23°C), and the oven was heated to 230°C, with the heating rate adjusted so that the temperature increased from room temperature (23°C) to 230°C within 1 hour and 30 minutes. The prepared samples were held at 230°C for 2 hours to simulate aging. The aged samples were slowly cooled to 100°C and then removed from the oven. The condition of the samples was then observed. Generally speaking, EMC molded wafers cause large warping at high temperatures, which means that if the temporary adhesive film does not have strong adhesion and excellent thermal stability, delamination may occur.

[0129] For the 180°C hot plate test (glass-to-glass bonding), a sample of the temporary adhesive film was bonded to a glass carrier (an 8-inch diameter disk) on each side. Specifically, one of the two glass carriers was bonded to the pressure-sensitive adhesive layer side of the temporary adhesive film, and the other was bonded to the laser-peelable elastomer layer side. The prepared sample (with the temporary adhesive film bonded to the two glass carriers) was placed directly on a 180°C hot plate (with the laser-peelable elastomer layer side) without heating and held at 180°C for 30 minutes to simulate an aging process. During this period, the sample was observed to check for changes or defects, such as delamination.

[0130] Examples 1 to 16 (EX1 to EX16)

[0131] For Examples 1 to 16, temporary adhesive films were prepared according to the manufacturing process of Examples 1 to 7, as described below. Manufacturing Example 1 - Manufacturing of Laser-Releasable Elastomer Layer Mixture

[0132] The premixed carbon solution was prepared as follows: 6.66 g of carbon black (250 nm particle size) from Cabot Corporation, USA, and 2.53 g of alumina-coated titanium dioxide powder (Huntsman) with a particle size of 250 nm were added to 100 g of organic solvent (95 wt% polar solvent (ethyl acetate / methyl ethyl ketone 50:50), 5 wt% aromatic solvent (toluene)). Then, 3 g of polymeric dispersant (Hypermer, supplied by Croda International Plc, UK) was added. ™ KD6) was mixed with a stirrer for 10 minutes. For dispersion, a mill was used for over 30 minutes. To control heat generation during milling, a cooler was used so that the temperature could be kept below 40°C. All types of milling machines capable of nanometer dispersion, such as nanomills, basket mills, and Horn-type ultrasonic processing equipment, are suitable. Then, 20g of acrylic elastomer resin SG-708-6 (supplied by Nagase Chemtex Corporation) was added to the premixed carbon solution and dispersed again using a mill for 30 to 45 minutes. Manufacturing Example 2 - Casting of Laser-Releasable Elastomer Layer

[0133] The mixture from Manufacturing Example 1 was applied to a 50µm PET pad, and then the solvent was dried at 90°C for 2 minutes to complete the laser-peelable film layer, resulting in a thickness of 5µm to 15µm after drying. Manufacturing Example 3 - Manufacturing of Pressure-Sensitive (Siloxane) Adhesive Mixture

[0134] Add 2.28g of biphenyl peroxide curing agent to 80g of aromatic polar solvent (95% by weight toluene, 5% by weight xylene), and then stir to completely dissolve the curing agent. After dissolution, add 100g of condensation-reactive siloxane adhesive additive (Dowsil from Dow Chemical). ™ (Q2-7406) and stir for 20 minutes. After stirring, deaerate for 30 minutes. Manufacturing Example 4 - Coating a pressure-sensitive adhesive layer on the first surface of a PI core film

[0135] The mixture from Manufacturing Example 3 was applied to a 25µm polyimide film (supplied by PI Advanced Materials Co., Ltd., South Korea) to achieve a dried thickness of 50µm. After coating, the film was dried and cured at 185°C for 3 minutes to complete the adhesive coating. A comma roller was used for coating. A slit die / lip die could also be used for coating. A primer coating was applied to the polyimide film prior to coating it with the mixture from Manufacturing Example 3. Manufacturing Example 5 - Manufacturing of Epoxy Thermosetting Adhesive Mixture

[0136] 30 g of epoxy resin, 20 g of solid curing agent, and 100 g of organic solvent (95 wt% polar solvent (methyl ethyl ketone or ethyl acetate), 5 wt% aromatic solvent (toluene)) were mixed at room temperature (23°C) for 20 minutes. After adding 50 g of binder to the prepared solution, the mixture was stirred at 10 rpm for 30 minutes. For Example 1, the epoxy resin, curing agent, and binder shown in Table 1 were used. For Examples 2 to 16, the epoxy resin, curing agent, and binder shown in Table 1 were used, and the preparation process of Example 5 was followed as described for Example 1, wherein the amounts of epoxy resin, curing agent, and binder are shown in Table 1.

[0137] To provide coating properties, the solids content of the epoxy thermosetting adhesive mixture was adjusted to 10% to 25% for all embodiments. Methyl ethyl ketone or ethyl acetate was used as the diluent, and a small amount of toluene (5% by weight, based on the total weight of the solvent) was added. All resin contents, including the adhesive, as shown in Table 1 are based on solids content. Manufacturing Example 6 - Coating an epoxy thermosetting adhesive layer onto the second surface of a PI core film and then applying a laser-peelable adhesive layer. Elastomer layer combination

[0138] The mixture from Manufacturing Example 5 was applied to the polyimide side of the polyimide / siloxane adhesive tape prepared in Manufacturing Example 4. After coating, the sample was dried and cured at 145°C for 2 minutes. The target thickness after drying was 20 µm. After coating the epoxy thermosetting adhesive layer, a laser-peelable elastomer layer prepared as in Manufacturing Example 2 was laminated onto the epoxy thermosetting adhesive layer using a heated roller at 80°C via a lamination process. Manufacturing Example 7 - Aging

[0139] All film layers, including the epoxy thermosetting adhesive layer, can be chemically stabilized by aging at 45°C for 17 hours after coating. Without aging, there is no significant difference in adhesion between the epoxy thermosetting adhesive layer and the polyimide core film layer; however, when introduced into processes involving rapid heating, cracking may occur due to shrinkage caused by rapid curing. In the case of siloxane pressure-sensitive adhesives, issues such as residue buildup during high-temperature processes may arise if aging is not performed.

[0140]

[0141] Comparative Example 1 and Comparative Example 2 (CEX1 and CEX2)

[0142] For Comparative Example 1, a temporary adhesive film was prepared by applying a siloxane pressure-sensitive adhesive as an intermediate adhesive, i.e., instead of an epoxy thermosetting adhesive. For Comparative Example 2, a temporary adhesive film was prepared by directly coating a laser-peelable elastomer layer onto the back side of a polyimide core film without an intermediate adhesive (i.e., without an epoxy thermosetting adhesive layer). For Comparative Examples 1 and 2, the method and formulation of the siloxane pressure-sensitive adhesive coated on the polyimide core film were the same as in the examples described above. Furthermore, the formation of the laser-peelable elastomer layer was the same. However, in the case of CEX1, an addition-curing siloxane pressure-sensitive adhesive was coated at a thickness of 30 µm onto the back side (polyimide side) of the pre-formed siloxane / polyimide film, and then the laser-peelable elastomer layer was laminated; that is, the addition-curing siloxane pressure-sensitive adhesive was used as an intermediate adhesive between the polyimide core film layer and the laser-peelable elastomer layer, instead of using an epoxy thermosetting adhesive layer as an intermediate adhesive. In Comparative Example 2, the laser-peelable elastomer layer mixture was directly coated onto the back side (polyimide side) of the pre-formed siloxane / polyimide film. After drying, the thickness of the laser-peelable elastomer layer was 10 µm, and the drying temperature was 90 °C. Test results (coating performance, adhesion, thermal stability) of Examples 1 to 16 and Comparative Examples 1 and 2

[0143] The coating performance of the epoxy thermosetting adhesive on the polyimide core film layer of all embodiments and comparative examples was studied using the above test methods, as well as the adhesion of the epoxy thermosetting adhesive layer to the polyimide core film layer and to the laser-peelable elastomer layer before and after curing. The thermal stability of all embodiments was studied using the above test methods. The test results of the embodiments are shown in Table 2.

[0144] The coating properties of all examples and Comparative Example 1, including the coating properties of the epoxy thermosetting adhesive, were good or excellent (see Table 2; results for CEX1 are not shown in Table 2). Comparative Example 2, which had no intermediate adhesive between the polyimide core film layer and the laser-peelable elastomer layer, showed the least complete coating properties (results for CEX2 are not shown in Table 2).

[0145] The adhesion properties of the epoxy thermosetting adhesive layer to the polyimide core film layer were evaluated before and after curing. After curing, all examples except Example 16 showed sufficient bond strength. In particular, when using liquid epoxy resin, the epoxy thermosetting adhesive layer exhibited high adhesion to the polyimide core film layer (Examples 13, 14, and 15). When comparing the results of examples (Examples 1 to 6) without the addition of a curing catalyst before curing, Example 4 (an adhesive resin with a high functional group (-COOH, -OH) content of 20 mg KOH / g) and Example 6 (with a high adhesive content) showed high bond strength. When comparing Examples 1, 7, and 8, the sample without a catalyst (Example 1) showed lower adhesion both before and after curing compared to the samples with added curing catalysts (Examples 7 and 8).

[0146] For all embodiments, the adhesion between the epoxy thermosetting adhesive layer and the laser-peelable elastomer layer is excellent, both before and after curing. This can be explained, without being bound by theory, by the fact that the adhesives for both the laser-peelable elastomer layer and the epoxy thermosetting adhesive layer are based on polar acrylic elastomers. Because acrylic adhesives of the same nature are used, the adhesion is very high when they are attached to each other. Due to the very high peel force between the epoxy thermosetting adhesive layer and the laser-peelable elastomer layer, the two layers cannot be separated and the peel value cannot be measured.

[0147] Thermal stability was evaluated using a 230°C oven test and a 180°C hot plate test. These tests were performed as described in the Test Methods section above. Examples 10, 12, and 15 (see Table 2) with curing initiation points in the range of 150°C to 170°C showed excellent results relative to thermal stability. The thermal stability results of Examples 10, 12, and 15 were superior to those of Examples 8 and 11 (with curing initiation points in the range of 80°C to 100°C). In comparison, the curing initiation points of the examples without added catalyst (Examples 1 to 6) were 200°C or higher. On the other hand, the results of the thermal stability test for the epoxy-free sample (Example 16) were not as expected (see Table 2; defects were observed overall in the 230°C oven test and the 180°C hot plate test). Example 16 is a reference example, and Examples 1 to 15 are examples according to this disclosure. Moreover, the thermal stability test results of Examples 1 to 6, which had no added curing catalyst and had a low degree of curing, were worse than the results of the thermal stability test of the examples with added curing catalyst (see Tables 1 and 2). Comparative evaluation of the thermal stability of Example 10 (EX10) and Comparative Examples 1 and 2 (CEX1 and CEX2)

[0148] The thermal stability of Example 10 and Comparative Examples 1 and 2 was evaluated using two methods: a 180°C hot plate test and a 230°C oven test. The 180°C hot plate test is an evaluation method simulating the metal deposition process during the fan-out process of the redistribution layer (RDL) buildup. The RDL process is a semiconductor packaging process. In other words, the 180°C hot plate test is an evaluation method simulating the sputtering process during semiconductor processing. The 230°C oven test is an evaluation method simulating the curing process of the passivation layer during the redistribution layer (RDL) buildup; that is, the oven test is an evaluation method simulating the passivation curing process during semiconductor processing. The oven test with overall heating and the hot plate test with heating only one side can be considered different methods for testing thermal stability and thermal shock performance. Both tests require the use of a temporary adhesive film as disclosed herein.

[0149] For the 180°C hot plate test (glass-to-glass bonding), samples were prepared by bonding two glass carriers to temporary adhesive film samples prepared as described above for Example 10 and Comparative Examples 1 and 2. The 180°C hot plate test was performed as described above in the Test Methods section (Thermal Stability Test).

[0150] For Comparative Example 1, when a siloxane pressure-sensitive adhesive was used instead of an epoxy thermosetting adhesive as the intermediate adhesive, wrinkles were observed to form between the layers of the temporary adhesive film due to the melting of the intermediate adhesive (i.e., "defects were observed overall"). For Example 10, when an epoxy thermosetting adhesive was used as the intermediate adhesive between the polyimide core film layer and the laser-peelable elastomer layer, no defects were observed (i.e., "excellent" for the 180°C hot plate test). Similarly, for Comparative Example 2, when the laser-peelable elastomer layer and the polyimide core film layer were combined without an intermediate adhesive, no defects were observed (i.e., "excellent" for the 180°C hot plate test).

[0151] For the 230°C oven test (glass-wafer bonding), samples were prepared by bonding the glass carrier and the EMC (epoxy molding compound) molded wafer to temporary adhesive film samples prepared as described above for Example 10 and Comparative Examples 1 and 2. The 230°C oven test was performed as described above in the Test Methods section (thermal stability test).

[0152] For Example 10 and Comparative Example 1, i.e., for the samples prepared with an intermediate binder, the prepared samples were able to withstand the warpage of the EMC-molded wafer even at high temperatures (230°C), corresponding to an "excellent" evaluation in the 230°C oven test. For Comparative Example 2, where the laser-peelable elastomer layer was directly coated onto the polyimide core film without an intermediate binder, delamination was observed, and the prepared sample could not withstand the bending of the EMC-molded wafer at high temperatures, corresponding to an "overall observed defect" evaluation in the 230°C oven test.

[0153] Examples and comparative examples, as well as thermal stability tests, demonstrate that the temporary adhesive film disclosed herein can withstand high-temperature hot plate and oven processes without losing the properties of a flexible film, such as adhesive and mechanical properties.

[0154] For multilayer temporary adhesive films used in high-temperature semiconductor packaging processes, a high-heat-resistant siloxane adhesive layer, a polyimide core film layer, and a laser-peelable elastomer layer are required. However, the adhesion between the polyimide core film layer and the laser-peelable elastomer layer is a key factor determining the overall heat resistance of the temporary adhesive film. For the temporary adhesive film disclosed herein, effective bonding methods for different film materials used to bond the polyimide core film layer and the laser-peelable elastomer layer have been discovered.

Claims

1. A temporary adhesive film, the temporary adhesive film comprising: A polyimide core film layer, the polyimide core film layer having a first surface and a second surface; A pressure-sensitive adhesive layer is disposed on the first surface of the polyimide core film layer; An epoxy thermosetting adhesive layer is disposed on the second surface of the polyimide core film layer; and A laser-removable elastomer layer is disposed on the epoxy thermosetting adhesive layer.

2. The temporary adhesive film according to claim 1, wherein the epoxy thermosetting adhesive layer comprises an epoxy thermosetting adhesive, the epoxy thermosetting adhesive comprising an epoxy resin, a curing agent, and an adhesive.

3. The temporary adhesive film of claim 2, wherein the epoxy thermosetting adhesive comprises up to 55% by weight of the adhesive, based on the total solids content of the epoxy thermosetting adhesive.

4. The temporary adhesive film according to claim 2, wherein the weight ratio of the total amount of the epoxy resin and the curing agent to the amount of the adhesive is 1:9 to 9:

1.

5. The temporary adhesive film according to claim 2, wherein the epoxy resin comprises a multifunctional epoxy resin.

6. The temporary adhesive film according to claim 2, wherein the softening point of the epoxy resin is at most 70°C.

7. The temporary adhesive film according to claim 2, wherein the curing agent is selected from the group consisting of: amine-based curing agents, phenol-based curing agents, acid anhydride curing agents, peroxide curing agents, imidazole curing agents, and combinations thereof.

8. The temporary adhesive film according to claim 1, wherein the curing initiation point of the epoxy thermosetting adhesive is at least 120°C and at most 180°C.

9. The temporary adhesive film of claim 2, wherein the adhesive of the epoxy thermosetting adhesive comprises at least one of a rubber-based elastomer and an acrylic elastomer.

10. The temporary adhesive film of claim 2, wherein the adhesive of the epoxy thermosetting adhesive comprises an acrylic elastomer, and wherein the acrylic elastomer comprises an acrylic polymer made by polymerizing at least one acrylic monomer selected from the group consisting of: ethyl acrylate, butyl acrylate, glycidyl methacrylate, acrylic acid, acrylonitrile, and combinations thereof.

11. The temporary adhesive film of claim 10, wherein the acrylic polymer comprises a polar functional group, and wherein the polar functional group is selected from the group consisting of nitrile groups, carboxyl groups, hydroxyl groups, glycidyl groups, amine groups, and combinations thereof.

12. The temporary adhesive film according to claim 11, wherein the polar functional group is a carboxyl group and / or a hydroxyl group, and wherein the acrylic polymer contains at least 1 mg KOH / g of the polymer as a polar functional group.

13. The temporary adhesive film according to claim 12, wherein the acrylic polymer comprises a polar functional group between 1 mg KOH / g polymer and 25 mg KOH / g polymer.

14. The temporary adhesive film of claim 2, wherein the adhesive has a glass transition temperature of at least -20°C and at most 60°C.

15. The temporary adhesive film according to claim 1, wherein the thickness of the epoxy thermosetting adhesive layer is from 10 µm to 45 µm.

16. The temporary adhesive film of claim 1, wherein the pressure-sensitive adhesive comprises a siloxane.

17. The temporary adhesive film of claim 1, wherein the laser-peelable elastomer layer comprises an acrylic elastomer.

18. The temporary adhesive film of claim 1, wherein the laser-peelable elastomer layer comprises carbon black.

19. The temporary adhesive film of claim 1, wherein the laser-peelable elastomer layer comprises an inorganic filler.

20. The temporary adhesive membrane of claim 19, wherein the inorganic filler comprises at least one of titanium dioxide or silicon dioxide.

21. The temporary adhesive film of claim 19, wherein the inorganic filler comprises at least one of alumina-coated titanium dioxide or silicon dioxide.

22. The temporary adhesive film according to claim 1, wherein the temporary adhesive film further comprises a first pad disposed on the pressure-sensitive adhesive layer opposite to the polyimide core film layer.

23. The temporary adhesive film according to claim 1, wherein the temporary adhesive film further comprises a second pad disposed on the laser-peelable elastomer layer opposite to the epoxy thermosetting adhesive layer.

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