WO2019130185A1

WO2019130185A1 - Thermally curable two part processing adhesive composition

Info

Publication number: WO2019130185A1
Application number: PCT/IB2018/060473
Authority: WO
Inventors: Ralph R. Roberts; Eric G. Larson; Andrew B. Lee
Original assignee: 3M Innovative Properties Company
Priority date: 2017-12-29
Filing date: 2018-12-20
Publication date: 2019-07-04
Also published as: TWI821232B; TW201934691A; JP2021509135A; KR20200104866A; JP7262468B2

Abstract

Two part, curable, liquid adhesive compositions have a Part A and a Part B. Part A includes a first free radically polymerizable liquid composition, and a first peroxide initiator composition that generates free radicals upon reaction with an amine. Part B includes a second free radically polymerizable liquid composition, a second peroxide initiator that generates free radicals at a temperature of greater than 150°C and is not amine-reactive, and an amine. Mixtures of Part A and Part B can be heated to a temperature of at least 55°C to partially cure, and heated to a temperature of at least 150°C to fully cure.

Description

THERMALLY CURABLE TWO PART PROCESSING ADHESIVE

COMPOSITION

Field of the Disclosure

This disclosure relates to two part thermally curable adhesive compositions useful in a variety of processing applications.

Background

Adhesives have been used for a variety of marking, holding, protecting, sealing and masking purposes. Adhesives are frequently supplied as tapes generally comprise a backing, or substrate, and an adhesive. In other uses, adhesives are supplied as curable liquids. Frequently adhesives are used to hold together components permanently or at least for extended periods of time. In other uses, adhesives are used to hold together components only temporarily, often so that some processing step or steps can be carried out on one or more of the components.

Adhesive tapes that are used in the manufacture of articles to protect or temporarily hold in place components of the article during processing are sometimes called processing tapes. Examples of processing tapes include, for example, wafer dicing tapes, where the dicing tape may also function as a die attach adhesive for dicing thinned wafers and subsequent die attach operations of the diced chips in semiconductor device fabrication. Another example of a processing tape is a masking tape, where the masking tape is applied to a surface to cover it and protect it from being painted, the paint is applied, and the masking tape is removed to give a surface with adjacent areas that are painted and unpainted. Typically the processing tape is not retained in the final article, but is removed following one or more processing steps. In some instances, processing tapes are subjected to extreme conditions such as high temperatures, high pressures, exposure to chemicals such as solvents, abrasives, etching materials, and the like and yet are expected to remain adhered during the processing steps without flowing, dripping or slipping and also to be removable after the processing steps are completed.

In other applications, curable liquid adhesives are used to temporarily hold processable components on a surface to permit processing steps to be carried out. Curable liquid adhesives are ones that are applied as a liquid and cured to form a relatively rigid solid adhesive bond. The curing can be carried out in a variety of ways, by the application of heat, radiation, or by the simple mixing to two reactive compounds. The cured adhesive bond generally has high structural strength, permitting vigorous processing steps to be carried out, including steps such as welding, soldering, thinning, grinding, polishing, heating, applying pressure, and the like. Upon completion of the processing steps, the processed component can be removed from the adhesive layer.

Examples of processes that use layers of processing adhesives include US Patent No. 7,534,498 (Noda et al.) which describes the use of adhesive layers in laminate bodies for manufacturing ultrathin substrates; US Patent Publication No. 2012/0263946 (Mitsukura et al.) which describes methods of manufacturing semiconductor devices which includes the steps of forming an adhesive layer and B-stage curing the adhesive layer by irradiation; and US Patent Publication No. 2014/0210075 (Lee et al.) which describes methods for processing substrates including providing a bonding layer between a substrate and carrier.

Summary

Disclosed herein are two part, curable, liquid processing adhesive compositions, articles that contain cured processing adhesive compositions, and methods of processing substrates utilizing the two part, curable, liquid processing adhesive compositions. In some embodiments, the two part, curable, liquid adhesive composition comprises a Part A and a Part B, wherein upon mixing Part A and Part B and heating the formed mixture to a temperature of at least 55°C the mixture partially cures, and upon heating to a temperature of at least l50°C the mixture fully cures. Part A comprises a first free radically polymerizable liquid composition, and a first peroxide initiator composition that generates free radicals upon reaction with an amine. Part B comprises a second free radically polymerizable liquid composition, a second peroxide initiator that generates free radicals upon heating to a temperature of greater than l50°C and wherein the second peroxide initiator does not react with an amine to generate free radicals, and an amine.

Also disclosed are articles. In some embodiments the article comprises a substrate with a first major surface and a second major surface, with a first release coating on at least a portion of the second major surface, a processable wafer with a first major surface and a second major surface, with a second release coating on at least a portion of the first major surface, and a cured adhesive composition layer with a first major surface and a second major surface, disposed between the substrate and the processable wafer such that the second major surface of the cured adhesive composition layer is in contact with the first release coating and the first major surface of the cured adhesive composition layer is in contact with the second release coating. The cured adhesive composition layer is the cured two part adhesive described above.

In some embodiments the method of preparing an article comprises generating an assembly, and processing that assembly. Generating the assembly comprises providing a substrate with a first major surface and a second major surface, with a first release coating on at least a portion of the second major surface, providing a processable wafer with a first major surface and a second major surface, with a second release coating on at least a portion of the first major surface, disposing a curable adhesive composition layer between the substrate and the processable wafer such that the second major surface of the curable adhesive composition layer is in contact with the first release coating and the first major surface of the curable adhesive composition layer is in contact with the second release coating, heating the substrate, curable adhesive layer, processable wafer construction to a temperature of at least 55°C to partially cure the curable adhesive layer, and heating the substrate, curable adhesive layer, processable wafer construction to a temperature of at least l50°C to fully cure the curable adhesive layer. The curable adhesive composition is the two part curable adhesive described above. The adhesive composition may be mixed prior to disposing upon the substrate surface or one part can be disposed on one substrate surface and the other part can be disposed on the other substrate surface and the two substrates can be brought together to contact the two parts of the adhesive.

Brief Description of the Drawings

The present application may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings.

Figure 1 is a cross sectional view of an embodiment of a method of the present disclosure. Figure 2 is a cross sectional view of another embodiment of a method of the present disclosure.

Figure 3 is a cross sectional view of yet another embodiment of a method of the present disclosure.

Figure 4 is a graph of DSC (Differential Scanning Calorimetry) data from the Examples section.

In the following description of the illustrated embodiments, reference is made to the accompanying drawings, in which is shown by way of illustration, various embodiments in which the disclosure may be practiced. It is to be understood that the embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure. The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

Detailed Description

The use of adhesives is increasing in a wide range of applications. Among the classes of adhesive compositions are adhesive tapes, which consist of a layer of adhesive, typically a pressure sensitive adhesive, on a backing layer, and curable liquid adhesives. The most common use for adhesives is in bonding, that is to say adhering one substrate to another substrate. Often the adhesive is designed to adhere permanently or at least for a long time period, and the adhesive is incorporated into the final article. Examples range from optical adhesives that bind together layers of film for use on a display screen to structural adhesives that hold bumpers onto cars.

There is however a specialized class of adhesive articles that are not designed to adhere together articles permanently or for a long time, but rather are described as “processing” articles. By this it is meant that the adhesive is meant to temporarily hold together components or provide a temporary protective layer for components so that a process or series of processes can be carried out. After the processing steps, the adhesive article is removed. Typically it is desirable that the removal of the adhesive article leaves behind no residue or residue that is easily removable. A simplistic example of an adhesive processing article is masking tape. In one wishes to paint a wall without getting paint on the base boards, one applies masking tape to the base boards at the wall/base board interface. The wall is then painted and the masking tape functions to prevent paint from getting on the base board. The masking tape is removed, leaving behind no residue.

Current industrial needs, especially in the electronic and optical industries, as well as in the manufacture of consumer goods and other articles, have requirements much more complex and specialized than the simplistic example presented above. An Illustrative example is the process of semiconductor wafers. The wafers are typically small articles to which a variety of processing steps especially surface modification steps. In many instances a processing adhesive is used to hold the wafer while these processes are carried out. Many of these steps involve vigorous physical processes such as polishing and grinding, as well as the precise application of surface elements. As electronic devices demand thinner and thinner wafers, one processing step that is becoming increasingly important is wafer thinning, where a wafer is thinned to a thickness of less than 100 micrometers. Therefore, it is necessary to have a processing adhesive that will hold the wafer firmly in place during these steps. Upon completion of the processing steps, the wafer must be removable from the processing article. Such a processing adhesives have a variety of requirements. Another trend in the wafer processing industry is the use of silicon substrates, replacing glass as a substrate, and this changes also the adhesive requirements as silicon is a very different surface from glass.

The requirements for adhesives that can be used for the processing of semiconductor wafers are in many instances contradictory. For example, the adhesives need to be coatable and have sufficient flow so as to be able to encompass wafer surfaces that may be structured, and yet must not flow upon heating. If the adhesive flows upon heating it will leak out from between the substrates. Additionally, the adhesives must bond firmly to permit the wafers to undergo processing steps, including wafer thinning steps, and the adhesive must also be removable once the processing steps are completed.

Among the candidates for coatable, curable adhesives are one part adhesives and two part adhesives. As the names imply, one part adhesives contain all of the materials of the curable adhesive in a single composition, whereas two part curable adhesives have two parts that are kept separate until the time of use. Each type has advantages and disadvantages. The one part compositions have issues with shelf life, since the composition is curable it often is difficult to prevent curing prior to the time of use. In some instances the composition is stored cold or even frozen to prevent premature curing. In two part adhesives, the overall composition is divided into two parts which are kept separate from each other so no premature curing can occur. An example of a two part curable adhesive is a two part urethane adhesive. In this adhesive an isocyanate-functional material is present in one part and a hydroxyl -functional material is present in the other part. Typically a curing catalyst such as dibutyl tin dilaurate or tertiary amine is included with the hydroxyl -functional part and one or both parts may include additional non reactive materials such as fillers, etc. When the two part adhesive is room temperature curable, upon mixing the mixture begins to cure. Other two part adhesives are thermally curable, such that little or no curing occurs until the mixture is heated. While two part curable adhesives have advantages over one part adhesives as far as shelf life is concerned, two part adhesives have the complication of requiring mixing of the two parts at the proper ratio to give the desired curable mixture. For example if too much of part one is mixed with a deficiency of part two, the cured composition will not have the desired properties.

Disclosed herein are two part, curable, liquid adhesive compositions suitable for use as processing adhesives. The composition comprises a Part A that includes a first free radically polymerizable liquid composition, and a first peroxide initiator composition that generates free radicals upon reaction with an amine, and a Part B comprising a second free radically polymerizable liquid composition, a second peroxide initiator that generates free radicals upon heating to a temperature of greater than l50°C and wherein the second peroxide initiator does not react with an amine to generate free radicals, and an amine. Upon mixing Part A and Part B and heating the formed mixture to a temperature of at least 55°C the mixture partially cures, and upon heating to a temperature of at least l50°C the mixture fully cures. This two stage curing mechanism permits partial curing to provide a composition that does not readily flow, but does not have the full adhesive strength of the fully cured composition.

The term“curing” as used herein refers to polymerization. The term curing is used broadly in the art and often refers to crosslinking or vulcanization. In this disclosure, curing simply means polymerization is not synonymous with crosslinking, but may include crosslinking.

Also disclosed are articles that comprise in sequence: a substrate, a cured adhesive layer, and a processable object such as a wafer. In some embodiments, one or more of the surfaces in contact with the cured adhesive layer may be treated with release coatings to facilitate their removal from the adhesive layer. The cured adhesive layer is the two part, curable, liquid adhesive compositions described above that has been cured. Methods for preparing and processing these articles are also disclosed.

It is important to note that the currently disclosed two part thermally curable adhesive is useful not only for the processing of semiconductor wafers, but has a much wider applicability. The adhesive is particularly well suited to the specific needs of semiconductor wafer processing, but is not limited to use in this process.

Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.

As used in this specification and the appended claims, the singular forms "a", "an", and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise. For example, reference to "a layer" encompasses embodiments having one, two or more layers. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

The term“adhesive” as used herein refers to polymeric compositions useful to adhere together two adherends. Examples of adhesives include two part, curable, liquid adhesive compositions.

The term“ethylenically unsaturated” refers to materials that are polymerizable by free radical polymerization methods and contain terminal groups with double bonds. Among the ethylenically unsaturated groups are (meth)acrylate groups and (meth)acrylamide groups.

The term“free radically polymerizable” refers to materials that contain double bonds and are polymerizable by free radical polymerization methods. Among free radically polymerizable groups are (meth)acrylate groups, (meth)acrylamide groups, and maleimidies.

The term“(meth)acrylate” refers to monomeric acrylic or methacrylic esters of alcohols. Acrylate and methacrylate monomers or oligomers are referred to collectively herein as "(meth)acrylates”. The term“(meth)acrylate-based” when used to describe polymers, refers to polymers that are prepared from (meth)acrylate monomers or reactive materials that contain (meth)acrylate functionality such as (meth)acrylate oligomers. These polymers may contain only (meth)acrylate monomers or they contain monomers that are co-reactive with (meth)acrylates. The (meth)acrylates may be difunctional or higher functionality. Similarly, the term“(meth)acrylamide” refers to both acrylamide and methacrylamide groups. The structure of (meth)acrylamides is similar to (meth)acrylates except that instead of an ester linkage (R-O-(CO)-), where R is an alkyl, aryl or substituted alkyl or aryl group and (CO) is a carbonyl group C=0; they have an amide linkage of the type (R^aR^bN-(CO)-), where R^a and R^b is each independently a hydrogen atom or an alkyl or aryl group, and (CO) is a carbonyl group C=0.

As used herein, the term "polymer" refers to a polymeric material that is a homopolymer or a copolymer. As used herein, the term "homopolymer" refers to a polymeric material that is the reaction product of one monomer. As used herein, the term "copolymer" refers to a polymeric material that is the reaction product of at least two different monomers.

The term "oligomer" refers to a polymer molecule having 2 to 10 repeating units (e.g., dimer, trimer, tetramer, and so forth) having a capability of forming chemical bonds with the same or other oligomers in such manner that longer polymeric chains can be formed therefrom.

The term“alkyl” refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. The alkyl can be linear, branched, cyclic, or combinations thereof and typically has 1 to 20 carbon atoms. In some embodiments, the alkyl group contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl.

As used herein, the term“wet out” when referring to an adhesive layer refers to the ability of the adhesive to spread out upon and bond to the contact surface.

The terms “room temperature” and “ambient temperature” are used interchangeably and refer to a temperature of from 20-25°C.

The terms“weight %”, % by weight”,“mass%”, and“% by mass” are used interchangeably and when referring to components of curable compositions refer to percentage of that component by weight relative to 100% of the weight of the entire curable composition.

The terms“Tg” and“glass transition temperature” are used interchangeably and refer to the glass transition temperature of a polymeric composition. Unless otherwise specified, the glass transition temperature, if measured, is measured by DSC (Differential Scanning Calorimetry) using well understood techniques (typically with a heating time of l0°C per minute). More typically the Tg is calculated using the well-known and understood Fox equation with monomer Tg values provided by the monomer supplier, as is well understood by one of skill in the polymer arts.

Disclosed herein are two part, curable, liquid adhesive compositions suitable for use as processing adhesives. The composition comprises a Part A that includes a first free radically polymerizable liquid composition, and a first peroxide initiator composition that generates free radicals upon reaction with an amine, and a Part B comprising a second free radically polymerizable liquid composition, a second peroxide initiator that generates free radicals upon heating to a temperature of greater than l50°C and wherein the second peroxide initiator does not react with an amine to generate free radicals, and an amine. Upon mixing Part A and Part B and heating the formed mixture to a temperature of at least 55°C the mixture partially cures, and upon heating to a temperature of at least l50°C the mixture fully cures.

A wide variety of ethylenically unsaturated materials are suitable for use in the first free radically polymerizable liquid composition of Part A. The first free radically polymerizable liquid composition of Part A may include a single ethylenically unsaturated material or a mixture of different free radically polymerizable materials. Typically the first free radically polymerizable liquid composition of Part A comprises a mixture of free radically polymerizable materials.

In some embodiments, the first free radically polymerizable liquid composition of Part A comprises a mixture of an ethylenically unsaturated polymer or oligomer, and at least one mono-functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof.

A wide range of ethylenically unsaturated polymers or oligomers are suitable. Particularly suitable are (meth)acrylate-functional polybutadiene polymers. Examples of suitable polymers include CN307 a di-acrylate polybutadiene commercially available from Cray Valley, and EMA-3000, an acrylate-modified polybutadiene commercially available from Nippon Soda Co. An example of a particularly suitable ethylenically unsaturated polymer is EMA-3000, an acrylate-modified polybutadiene commercially available from Nippon Soda Co.

The first free radically polymerizable reaction mixture also comprises at least one mono-functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof. In some embodiments, the monofunctional (meth)acrylate contains an alkyl or aryl group that has an average of about 4 to about 14 carbon atoms. The alkyl or aryl group can optionally contain oxygen atoms in the chain thereby forming ethers. Examples of suitable monofunctional (meth)acrylates include, but are not limited to, 2-methylbutyl acrylate, isooctyl acrylate, lauryl acrylate, 4- methyl-2-pentyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, isodecyl acrylate, isodecyl methacrylate, and isononyl acrylate. Other examples include, but are not limited to, poly-ethoxylated or -propoxylated methoxy (meth)acrylates such as acrylates of CARBOWAX (commercially available from ETnion Carbide) and NK ester AM90G (commercially available from Shin Nakamura Chemical, Ltd., Japan) and silicone polyether (meth)acrylates. Other suitable monofunctional (meth)acrylate monomers include aryloxyl substituted groups such as phenoxyethyl acrylate.

In some embodiments, the first free radically polymerizable liquid may include a monofunctional (meth)acrylamide. Examples include, but are not limited to, acrylamide, methacrylamide, N-methyl acrylamide, N-ethyl acrylamide, N- hydroxyethyl acrylamide, diacetone acrylamide, N,N-dimethyl acrylamide, N, N-diethyl acrylamide, N-ethyl -N- aminoethyl acrylamide, N-ethyl-N- hydroxyethyl acrylamide, N,N-dihydroxyethyl acrylamide, t-butyl acrylamide, N,N-dimethylaminoethyl acrylamide, and N-octyl acrylamide.

In some embodiments the first free radically polymerizable liquid comprises a maleimide monomer. This monomer may be maleimide or a substituted maleimide. Typically substituted maleimides are N-substituted maleimides where the substituents are alkyl or aryl groups.

In some embodiments, the first free radically polymerizable liquid comprises a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide. Examples of useful multifunctional (meth)acrylates include, but are not limited to, di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates, such as l,6-hexanediol di(meth)acrylate, poly(ethylene glycol) di(meth)acrylates, polybutadiene di(meth)acrylate, polyurethane di(meth)acrylates, and propoxylated glycerin tri(meth)acrylate, and mixtures thereof. Examples of polyfunctional (meth)acrylamides and maleimides are less common but include, for example, N.N’-(l,2-dihydroxyethylene)bisacrylamide, and N,N’-(o- phenylene)dimaleimide, N,N’ -(1,3 -phenyl ene)dimaleimide, and N,N’-(l,4- phenylene)dimaleimide. In some embodiments, the first free radically polymerizable liquid comprises tricyclodecanediol diacrylate.

The Part A composition also comprises a first peroxide initiator composition that generates free radicals upon reaction with an amine. This initiation reaction is often referred to as a redox coupling reaction and the peroxide/amine reactants are referred to as redox couple. In the peroxide/amine redox couple, the peroxide is the oxidizing agent or electron acceptor, and the amine is the reducing agent or electron donator. Generally benzoyl peroxide is used as the peroxide component of the redox couple. The identity of the amine component of the redox couple is described below in the description of Part B of the curable composition.

The amount of first peroxide initiator present in Part A can vary widely depending upon a variety of different parameters including the amount and identity of the amine component present in the Part B of the curable composition. Typically the first peroxide initiator composition comprises 0.1 to 2.0 weight % of at least one peroxide initiator, based upon the total weight of free radical polymerizable liquid in Part A.

In addition to the first free radically polymerizable liquid and a first peroxide initiator composition that generates free radicals upon reaction with an amine, the Part A composition may contain optional other additives as long as they do not interfere with the polymerization of the components of the first free radically polymerizable liquid, with the redox reaction of the first peroxide initiator, or with the final properties of the cured adhesive composition. Examples of suitable optional additives include fillers, antioxidants, stabilizers, and the like. Optional additives, if used typically are included in amounts of 0.1-5% by weight based on the total weight of the curable components of the curable composition.

In some particular embodiments of the two part, curable, liquid adhesive composition, the first free radically polymerizable liquid composition comprises a mixture comprising 60-85 weight % of an ethylenically unsaturated polymer or oligomer, and 15- 40 weight % of a mono-functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof. In some embodiments, the ethylenically unsaturated polymer or oligomer comprises at least one (meth)acrylate-functional polybutadiene. In these embodiments, the mono functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof, comprises one or more alkyl or aryl (meth)acrylate, alkylene or arylene di(meth)acrylate, silicone polyether (meth)acrylate, or a combination thereof.

The two part, curable, liquid adhesive compositions suitable for use as processing adhesives also comprises a Part B comprising a second free radically polymerizable liquid composition, a second peroxide initiator that generates free radicals upon heating to a temperature of greater than l50°C and wherein the second peroxide initiator does not react with an amine to generate free radicals, and an amine.

A wide variety of ethylenically unsaturated materials are suitable for use in the second free radically polymerizable liquid composition of Part B. The second free radically polymerizable liquid composition of Part B may include a single ethylenically unsaturated material or a mixture of different free radically polymerizable materials. Typically the second free radically polymerizable liquid composition of Part B comprises a mixture of free radically polymerizable materials.

In some embodiments, the second free radically polymerizable liquid composition of Part B comprises a mixture of an ethylenically unsaturated polymer or oligomer, and at least one mono-functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof.

A wide range of ethylenically unsaturated polymers or oligomers are suitable. Particularly suitable are (meth)acrylate-functional polybutadiene polymers. An example of a suitable ethylenically unsaturated polymer is EMA-3000, an acrylate-modified polybutadiene commercially available from Nippon Soda Co.

The second free radically polymerizable reaction mixture also comprises at least one mono-functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof. In some embodiments, the monofunctional (meth)acrylate contains an alkyl or aryl group that has an average of about 4 to about 14 carbon atoms. The alkyl or aryl group can optionally contain oxygen atoms in the chain thereby forming ethers. Examples of suitable monofunctional (meth)acrylates include, but are not limited to, 2-methylbutyl acrylate, isooctyl acrylate, lauryl acrylate, 4- methyl-2-pentyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, isodecyl acrylate, isodecyl methacrylate, and isononyl acrylate. Other examples include, but are not limited to, poly-ethoxylated or -propoxylated methoxy (meth)acrylates such as acrylates of CARBOWAX (commercially available from ETnion Carbide) and NK ester AM90G (commercially available from Shin Nakamura Chemical, Ltd., Japan) and silicone polyether (meth)acrylates such as TEGO RAD 2300 from Evonic Industries. Other suitable monofunctional (meth)acrylate monomers include aryloxyl substituted groups such as phenoxy ethyl acrylate.

In some embodiments, the second free radically polymerizable liquid may include a monofunctional (meth)acrylamide. Examples include, but are not limited to, acrylamide, methacrylamide, N-methyl acrylamide, N-ethyl acrylamide, N- hydroxyethyl acrylamide, diacetone acrylamide, N,N-dimethyl acrylamide, N, N-diethyl acrylamide, N-ethyl -N- aminoethyl acrylamide, N-ethyl-N- hydroxyethyl acrylamide, N,N-dihydroxyethyl acrylamide, t-butyl acrylamide, N,N-dimethylaminoethyl acrylamide, and N-octyl acrylamide.

In some embodiments, the second free radically polymerizable liquid comprises a maleimide monomer. This monomer may be maleimide or a substituted maleimide. Typically substituted maleimides are N-substituted maleimides where the substituents are alkyl or aryl groups.

In some embodiments, the second free radically polymerizable liquid comprises a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide. Examples of useful polyfunctional (meth)acrylates include, but are not limited to, di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates, such as l,6-hexanediol di(meth)acrylate, poly(ethylene glycol) di(meth)acrylates, polybutadiene di(meth)acrylate, polyurethane di(meth)acrylates, and propoxylated glycerin tri(meth)acrylate, and mixtures thereof. Examples of polyfunctional (meth)acrylamides and maleimides are less common but include, for example, N.N’-(l,2-dihydroxyethylene)bisacrylamide, and N,N’-(o- phenylene)dimaleimide, N,N’ -(1,3 -phenyl ene)dimaleimide, and N,N’-(l,4- phenylene)dimaleimide. In some embodiments, the first free radically polymerizable liquid comprises tricyclodecanediol diacrylate.

The Part B composition also comprises a second peroxide initiator composition that is not reactive with an amine and that generates free radicals upon heating to a temperature of at least l50°C. Since the second peroxide initiator and the amine that serves as the reducing agent or electron donor to the first peroxide are mixed in the same part (Part B) it is desirable that the second peroxide and the amine not react with each to generate free radicals. Another way of putting this is that the second peroxide and the amine are not redox couple.

The second peroxide initiator is different from the first peroxide initiator. A variety of different peroxide initiators are suitable. One particularly suitable second peroxide initiator is n-butyl-4,4,-di(tert-butyl peroxy) valerate, commercially available from Arkema as LEIPEROX 230.

The amount of second peroxide initiator present in Part B can vary widely depending upon a variety of different parameters. Typically the second peroxide initiator composition comprises 0.1 to 2.0 weight % of at least one peroxide initiator, based upon the total weight of free radical polymerizable liquid in Part B.

The Part B composition also comprises an amine. The amine is reducing agent component of the redox couple that includes the first peroxide initiator. A wide variety of amines are suitable. Typically the amines are tertiary aromatic amines. Among the particularly suitable amines is DMT (N,N-dimethyl-p-toluidine).

The amount of amine can vary widely, depending upon a number of factors, including the amount of first peroxide initiator present in Part A. Typically the amine comprises 0.1 to 2.0 weight % based upon the total weight of free radical polymerizable liquid in Part B.

In addition to the second free radically polymerizable liquid, a second peroxide initiator composition, and an amine, the Part B composition may contain optional other additives as long as they do not interfere with the polymerization of the components of the second free radically polymerizable liquid, with the redox reaction of the amine with the first peroxide initiator, or with the final properties of the cured adhesive composition. Examples of suitable optional additives include fillers, antioxidants, stabilizers, and the like. Optional additives, if used typically are included in amounts of 0.1-5% by weight based on the total weight of the curable components of the curable composition.

In some particular embodiments of the two part, curable, liquid adhesive composition, the second free radically polymerizable liquid composition comprises a mixture comprising 60-85 weight % of an ethylenically unsaturated polymer or oligomer, and 15-40 weight % of a mono-functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acryl amide, or maleimide, or a combination thereof. In some embodiments, the ethylenically unsaturated polymer or oligomer comprises at least one (meth)acrylate-functional polybutadiene. In these embodiments, the mono-functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof, comprises one or more alkyl or aryl (meth)acrylate, alkylene or arylene di(meth)acrylate, or a combination thereof.

Also disclosed herein are articles comprising two substrates with a cured adhesive composition bonding the two substrates, where the cured adhesive composition is a cured two part, curable liquid adhesive composition as described above. A wide range of substrates are suitably bonded by the cured adhesive composition.

In some embodiments, the article comprises a substrate with a first major surface and a second major surface, with a first release coating on at least a portion of the second major surface, a processable wafer with a first major surface and a second major surface, with a second release coating on at least a portion of the first major surface, and a cured adhesive composition layer with a first major surface and a second major surface, disposed between the substrate and the processable wafer such that the second major surface of the cured adhesive composition layer is in contact with the first release coating and the first major surface of the cured adhesive composition layer is in contact with the second release coating.

A wide range of substrates are suitable for use in the articles of this disclosure. The substrates may be rigid or flexible, made of polymeric materials, metals, ceramics, wood, or glass. As the articles are often processing articles, the substrate is often a carrier substrate, meaning that the substrate provides a surface to which a wafer can be bonded and processed.

In some embodiments, the substrate has a first release coating on at least a portion of its second major surface. This release coating aids to limit the adhesion of the two part, curable liquid adhesive that is applied to it. By limiting the adhesion of the adhesive layer to the substrate surface, the article can be mechanically debonded after the processing steps have been carried out. The mechanical debonding process is explained in greater detail below. The release coating is typically a fluorocarbon polymer-based release coating. A wide range of fluorocarbon polymer-based release coatings are suitable, especially alkoxysilane-terminated fluoropolymers. The release coatings are typically thin coatings, in some embodiments the thicknes is from 1-10 micrometers.

The wafer is typically a semiconductor wafer that is to be processed. One of the suitable processing steps that is to be effected upon the wafer is wafer thinning, where the wafer is thinned to thickness of less than 100 micrometer thickness. The unprocessed wafer has a release coating on its first major surface, the surface that is not to be processed. This release coating may be the same as the release coating on the substrate surface or it may be different. Typically the release coating on the wafer is the same as that on the substrate.

In some embodiments, the first major surface of the processable wafer comprises a structured surface. By a structured surface it is meant that the surface is not smooth, but has protrusions extending from the surface of the wafer, as is common with semiconductor wafers.

Typically the thickness of the cured adhesive layer is from 10-100 micrometers. As mentioned above, the cured adhesive layer comprises a cured two part, curable liquid composition as described above. The two part, curable liquid composition comprises a Part A comprising a first free radically polymerizable liquid composition, and a first peroxide initiator composition that generates free radicals upon reaction with an amine, and a Part B comprising a second free radically polymerizable liquid composition, a second peroxide initiator that generates free radicals upon heating to a temperature of greater than l50°C and wherein the second peroxide initiator does not react with an amine to generate free radicals, and an amine.

Also disclosed are methods for preparing articles. The methods comprise generating an assembly. Generating the assembly comprises providing a substrate with a first major surface and a second major surface, with a first release coating on at least a portion of the second major surface, providing a processable wafer with a first major surface and a second major surface, with a second release coating on at least a portion of the first major surface, disposing a curable adhesive composition layer between the substrate and the processable wafer such that the second major surface of the curable adhesive composition layer is in contact with the first release coating and the first major surface of the curable adhesive composition layer is in contact with the second release coating, heating the substrate, curable adhesive layer, processable wafer construction to a temperature of at least 55°C to partially cure the curable adhesive layer, and heating the substrate, curable adhesive layer, processable wafer construction to a temperature of at least l50°C to fully cure the curable adhesive layer.

The curable adhesive layer comprises a two part, curable liquid composition as described above. The two part, curable liquid composition comprises a Part A comprising a first free radically polymerizable liquid composition, and a first peroxide initiator composition that generates free radicals upon reaction with an amine, and a Part B comprising a second free radically polymerizable liquid composition, a second peroxide initiator that generates free radicals upon heating to a temperature of greater than l50°C and wherein the second peroxide initiator does not react with an amine to generate free radicals, and an amine.

In a first embodiment of this method, disposing the curable adhesive composition layer between the substrate and the processable wafer comprises mixing Part A and Part B of the curable adhesive composition to form a curable adhesive mixture, disposing the curable adhesive mixture on the first major surface of the processable wafer to form a curable adhesive layer, and contacting the curable adhesive layer to the second major surface of the substrate.

In a second embodiment of this method, disposing the curable adhesive composition layer between the substrate and the processable wafer comprises mixing Part A and Part B of the curable adhesive composition to form a curable adhesive mixture, disposing the curable adhesive mixture on the second major surface of the substrate to form a curable adhesive layer, and contacting the curable adhesive layer to the first major surface of the processable wafer.

In a third embodiment of this method, disposing the curable adhesive composition layer between the substrate and the processable wafer comprises disposing Part A of the curable adhesive composition onto first major surface of the processable wafer to form a layer of Part A, disposing Part B of the curable adhesive composition onto the second major surface of the substrate to from a layer of Part B, and contacting the layer of Part A to the layer of Part B to form the curable adhesive layer.

In a fourth embodiment of this method, disposing the curable adhesive composition layer between the substrate and the processable wafer comprises disposing Part A of the curable adhesive composition onto second major surface of the substrate to form a layer of Part A, disposing Part B of the curable adhesive composition onto the first major surface of the processable wafer to from a layer of Part B, and contacting the layer of Part A to the layer of Part B to form the curable adhesive layer. In some embodiments, the method further comprises processing of the second major surface wafer surface of the generated assembly. A wide range of processing steps may be carried out, including but not limited to wafer thinning.

Upon completion of the desired processing step or steps, the method may further comprise the separation by mechanical separation of the substrate/adhesive/wafer assembly. In some embodiments, the mechanical separation may be carried out such that the first major surface of the processed wafer separates from the cured adhesive composition layer. In other embodiments, the mechanical separation may be carried out such that the first major surface of the cured adhesive composition layer separates from the second major surface of the substrate.

Examples

These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, unless noted otherwise. Solvents and other reagents used were obtained from Sigma-Aldrich Chemical Company; Milwaukee, Wisconsin unless otherwise noted. The following abbreviations are used: mm = millimeters; RPM = revolutions per minute; g = grams; Pa = Pascals; MPa = megaPascals; mL = milliliters; min = minutes. The terms“mass %”,“% by mass”, “weight%”,“wt%”, and“mass%” are used interchangeably.

Table of Abbreviations

Test Methods

Differential Scanning Calorimetry (DSC)

The DSC analysis was carried out on a Q2000 instrument from TA Instruments. Samples were analyzed in hermetically sealed aluminum pans in a nitrogen atmosphere.

Thermal Gravimetric Analysis (TGA)

The TGA analysis was carried out on a Q500 instrument from TA Instruments. Samples were heated in open pans in a nitrogen atmosphere with flow rate of 50 mL/min.

Mechanical Properties

The mechanical properties of elongation, tensile strength and modulus were measured on a MTS Insight 30 instrument from MTS System Corporation. Peel Force

The force required to peel a layer from a silicon wafer was measured using a MTS Insight 30 instrument from MTS System Corporation. A 90-degree peel angle was used. EXAMPLES

Formulation Preparation:

Stock solution preparation:

A series of stock solutions, designated A, B, C, L, and J, for use in the two-part composition were prepared by mixing the components listed in Table 1. The mixtures were homogenized in a DAC mixer for 3 minutes followed by vacuum degassing for about an hour.

Table 1. Preparation of Stock Solutions A-C and J, L.

Comparative Examples C1-C3 and Examples 1-6:

The de-gassed formulation mixtures listed in Table 2 were introduced into a pre- weighed aluminum DSC pan, the pan was hermetically sealed and subjected to DCS evaluation at a heating rate of 10°C / minute. The isotherm onset, heat flow and peak values are recorded in Table 2. The data reveals a significant lowering of polymerization onset to the 37 - 57°C range for these mixtures for BPO in the presence of DMT. In comparison, the isotherm onset for acrylate blend containing 1.0 mass % BPO was 113°C (Comparative Example 1). Figure 4 is a plot of the data from Table 2 showing that the high temperature decomposition of Organic Peroxide is independent of the mass% BPO in the mixtures but is linearly dependent on the mass% of Organic Peroxide in the mixtures. That is to say, BPQ has no effect on the high temperature thermal cure initiated by the Organic Peroxide and the two cure profiles are mutually independent.

Table 2. DSC evaluation of compositions comprising varied mass% of BPO, DMT and Organic Peroxide

In Example 7, a 1 : 1 mixture of Part B and Part C was made up. This resulted in Adhesive layer 1 mixture comprising 0 5 mass% of Organic Peroxide and 0.5 mass% DMT respectively. Similarly a 20 g amount a mixture of only Part A was used to give an Adhesive layer 2 comprising 1 mass % BPO and 0.0 mass % Organic Peroxide, respectively.

The surface of a polished bare Silicon waler with a 6 inch (15 centimeter) diameter and 700 micrometers thick were prepared by flushing with acetone and then isopropanol while on a spin coater. About 20 ml of a 2 wt% Fluoropolymer was spun on at 1000 rpm for 1 minute. The wafers were then baked in a forced air oven at 180°C for 1 hour. Onto a first Fluoropolymer coated wafer was spin coated Adhesive layer 1 at 1000 rpm for 1 minute. Adhesive layer 2 was then applied in a similar fashion on top of Adhesive layer 1. The coated wafer was then introduced into a vacuum chamber and, while under vacuum a second Fluoropolymer coated wafer was applied to form a construction:

Si wafer/Fluoropolymer/ Adhesive layer 1/ Adhesive layer 2/Fluoropolymer/ Si wafer The wafer stack was removed from the vacuum system and placed on a hot plate pre heated to 75C for 3 minutes with the first wafer facing downward (i.e. heating on the Adhesive layer 1 side). Within 10 seconds of heating, the second Si wafer could not be sheared from the lower first Si wafer nor was there any adhesive bleed out. The hot plate temperature w^?as ramped to ! 80°C at about lO°C / minute and held at 180°C for 30 minutes. On cooling the cured adhesive was readily extracted as a free-standing film from the wafer with a razor blade. The thermal and mechanical properties of the film was obtained and documented in Table 3.

For Examples 8-13, a series of two adhesive layer compositions were prepared with Adhesive Layer 1 having 20 g of the mixture of stock solutions shown in Table 3 and Adhesive Layer 2 having 20 g of the mixture of stock solutions shown in Table 3. Constructions as described for Example 7 were prepared.

Table 3. Thermal and mechanical strength optimization

Example 14: Simulated elevated temperature wafer processing

Onto a bare virgin silicon wafer 6 inch (15 centimeter) diameter and 700 micrometers thick pre-coated with PS Solution was spin coated Adhesive layer 1 using Stock solution J (1000 rpm for 25 sec) called Adhesive layer J, followed by coating Adhesive layer 2 using stock solution L (1000 rpm for 25 sec) called Adhesive layer L. The coated wafer was introduced onto a bonding chamber and pumped down to 50 Pa before contacting with a second Si carrier wafer pre-coated with Fluoropolymer. The bonded device was transferred to a UV chamber and subjected to UV irradiation during which time the irradiative source caused the device to heat to 70-80°C over 2 minutes. The device construction is as follows:

Si wafer/PS coating/ Adhesive layer J/ Adhesive layer L/Fluoropolymer/ Si wafer.

The second Si wafer could not be sheared from the lower first Si wafer nor was there any adhesive bleed out. Post cure was effected by heating at l80°C over 30 minutes as described above.

The bonded wafer was then mechanically thinned to 80 micrometers before subjecting to heat aging at 220°C/30 minutes in an oven. The heat aged sample showed no delamination of any of the layers, particularly confirming the thermal stability of the adhesive layer. The carrier layer was mechanically released and the recovered wafer/adhesive combination was then bonded to an aluminum plate with a double-sided adhesive tape. The peel force required for removal of the adhesive from the Si wafer/PS coating combination with de-bonding tape was 0.37 Newtons/25 mm.

Example 15. Two-part adhesive mixing while dispensing

About 20 ml each of Adhesive J and Adhesive L were introduced into separate syringes. The two adhesives were co-mixed while dispensing onto a cleaned bare Si wafer. The coated wafer was then introduced into a vacuum chamber and, while under vacuum a Fluoropolymer coated wafer was applied. The following represents the constaiction:

Si wafer/Adhesive layer J/Adhesive layer L/Fluoropoiymer/ Si wafer. The wafer stack was removed from the vacuum system and placed on a hot plate pre-heated to 75°C for 3 minutes. The hot plate temperature was ramped to 220°C at about 10°C/minute and then held at that temperature for 30 minutes. On cooling the carrier Fluoropolymer Si wafer was readily removed with a razor blade. A peel force value of 1.55 Newtons/25 mm was recorded for removal of the adhesive from the bare silicon wafer.

Example 16. Simulated elevated temperature structured wafer processing

A structured wafer comprising 75 micrometer high features was obtained from Micron Technology. The wafer was overcoated with a PS Solution layer by spinning at 1,000 rpm. The coated wafer was then processed as described in Example 14 to provide a supported structured wafer of the following configuration:

Staictured Si wafer/PS coating/Adhesive layer J/Adhesive layer L/Fluoropolymer/ Si wafer.

The bonded wafer was then mechanically thinned to 80 micrometers before subjecting to heat aging at 220°C/30 minutes in an oven. The heat aged sample showed no delamination.

The Si wafer/Fluoropolymer substrate was readily separated by use of a razor blade. The adhesive was readily peeled from the PS coated interface with a peak peel force value of 2.33 Newtons/25 mm. Lower peel values were recorded in the non- structured areas of the coupon (Compare also Example 14). Finally, the PS coating layer was removed from the structured wafer with a mixture of aqueous DMSO (dimethyl sulfoxide) and TMAH liquid silicon etchant to give the simulated processed thinned wafer.

Claims

What is claimed is:

1. A two part, curable, liquid adhesive composition comprising:

a Part A comprising:

a first free radically polymerizable liquid composition; and

a first peroxide initiator composition that generates free radicals upon reaction

with an amine; and

a Part B comprising:

a second free radically polymerizable liquid composition;

a second peroxide initiator that generates free radicals upon heating to a temperature of greater than l50°C and wherein the second peroxide initiator

does not react with an amine to generate free radicals; and

an amine;

wherein upon mixing Part A and Part B and heating the formed mixture to a temperature of at least 55°C the mixture partially cures, and upon heating to a temperature of at least l50°C the mixture fully cures.

2. The two part, curable, liquid adhesive composition of claim 1, wherein the first free radically polymerizable liquid composition comprises a mixture comprising:

60-85 weight % of an ethylenically unsaturated polymer or oligomer; and

15-40 weight % of a mono-functional (meth)acrylate, (meth)acrylamide, or maleimide,

a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof.

3. The two part, curable, liquid adhesive composition of claim 2, wherein the ethylenically unsaturated polymer or oligomer comprises at least one (meth)acrylate-functional polybutadiene.

4. The two part, curable, liquid adhesive composition of claim 2, wherein the mono- functional (meth)acrylate, (meth)acrylamide, or maleimide, a polyfunctional (meth)acrylate, (meth)acrylamide, or maleimide, or a combination thereof, comprises one or more alkyl or aryl (meth)acrylate, alkylene or arylene di(meth)acrylate, silicone polyether (meth)acrylate, or a combination thereof.

5. The two part, curable, liquid adhesive composition of claim 1, wherein the first peroxide initiator composition comprises 0.1 to 2.0 weight % of at least one peroxide initiator, based upon the total weight of free radical polymerizable liquid in Part A.

6. The two part, curable, liquid adhesive composition of claim 1, wherein the second peroxide initiator composition comprises 0.1 to 2.0 weight % of at least one peroxide initiator, based upon the total weight of free radical polymerizable liquid in Part B.

7. The two part, curable, liquid adhesive composition of claim 1, wherein the second free radically polymerizable liquid composition comprises a mixture comprising:

60-85 weight % of an ethylenically unsaturated polymer or oligomer; and

15-40 weight % of a mono-functional (meth)acrylate, (meth)acrylamide, or maleimide

8. An article comprising:

a substrate with a first major surface and a second major surface, with a first release

coating on at least a portion of the second major surface;

a processable wafer with a first major surface and a second major surface, with a second release coating on at least a portion of the first major surface; and a cured adhesive composition layer with a first major surface and a second major surface, disposed between the substrate and the processable wafer such that the second major surface of the cured adhesive composition layer is in contact with the first release coating and the first major surface of the cured adhesive composition layer is in

contact with the second release coating.

9. The article of claim 8, wherein at least one of the first release coating and second release coating comprises a fluorocarbon polymer-based release coating.

10. The article of claim 8, wherein the first major surface of the processable wafer comprises a structured surface.

11. The article of claim 8, wherein the cured adhesive composition layer comprises a cured curable composition, wherein the curable composition comprises:

a Part A comprising:

a first free radically polymerizable liquid composition; and

with an amine; and

a Part B comprising:

a second free radically polymerizable liquid composition;

does not react with an amine to generate free radicals; and

an amine;

12. A method of preparing an article comprising:

generating an assembly, wherein generating the assembly comprises: providing a substrate with a first major surface and a second major surface, with a first

release coating on at least a portion of the second major surface;

providing a processable wafer with a first major surface and a second major surface,

with a second release coating on at least a portion of the first major surface;

disposing a curable adhesive composition layer between the substrate and the processable wafer such that the second major surface of the curable adhesive composition layer is in contact with the first release coating and the first major surface

of the curable adhesive composition layer is in contact with the second release coating;

heating the substrate, curable adhesive layer, processable wafer construction to a temperature of at least 55°C to partially cure the curable adhesive layer; and heating the substrate, curable adhesive layer, processable wafer construction to a temperature of at least l50°C to fully cure the curable adhesive layer.

13. The method of claim 12, wherein the curable adhesive layer comprises a curable adhesive composition comprising:

a Part A comprising:

a first free radically polymerizable liquid composition; and

with an amine; and

a Part B comprising:

a second free radically polymerizable liquid composition;

does not react with an amine to generate free radicals; and

an amine; wherein upon mixing Part A and Part B and heating the formed mixture to a temperature of at least 55°C the mixture partially cures, and upon heating to a temperature of at least l50°C the mixture fully cures.

14. The method of claim 13, wherein disposing the curable adhesive composition layer between the substrate and the processable wafer comprises:

mixing Part A and Part B of the curable adhesive composition to form a curable adhesive mixture;

disposing the curable adhesive mixture on the first major surface of the processable wafer to form a curable adhesive layer; and

contacting the curable adhesive layer to the second major surface of the substrate.

15. The method of claim 13, wherein disposing the curable adhesive composition layer between the substrate and the processable wafer comprises:

disposing the curable adhesive mixture on the second major surface of the substrate to

form a curable adhesive layer; and

contacting the curable adhesive layer to the first major surface of the processable wafer.

16. The method of claim 13, wherein disposing the curable adhesive composition layer between the substrate and the processable wafer comprises:

disposing Part A of the curable adhesive composition onto first major surface of the

processable wafer to form a layer of Part A;

disposing Part B of the curable adhesive composition onto the second major surface of

the substrate to from a layer of Part B; and contacting the layer of Part A to the layer of Part B to form the curable adhesive layer.

17. The method of claim 13, wherein disposing the curable adhesive composition layer between the substrate and the processable wafer comprises:

disposing Part A of the curable adhesive composition onto second major surface of the

substrate to form a layer of Part A;

disposing Part B of the curable adhesive composition onto the first major surface of the processable wafer to from a layer of Part B; and

contacting the layer of Part A to the layer of Part B to form the curable adhesive layer.

18. The method of claim 12, further comprising:

processing of the second major surface wafer surface of the generated assembly.

19. The method of claim 18, further comprising:

separating the assembly by mechanical separation, such that the first major surface of

the processed wafer separates from the cured adhesive composition layer.

20. The method of claim 18, further comprising:

the cured adhesive composition layer separates from the second major surface of the

substrate.