WO2012115701A2 - Multilayered adhesive film - Google Patents

Multilayered adhesive film Download PDF

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Publication number
WO2012115701A2
WO2012115701A2 PCT/US2011/064789 US2011064789W WO2012115701A2 WO 2012115701 A2 WO2012115701 A2 WO 2012115701A2 US 2011064789 W US2011064789 W US 2011064789W WO 2012115701 A2 WO2012115701 A2 WO 2012115701A2
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WO
WIPO (PCT)
Prior art keywords
adhesive
adhesive layer
profile
multilayered
layer
Prior art date
Application number
PCT/US2011/064789
Other languages
French (fr)
Other versions
WO2012115701A3 (en
Inventor
Takano TADASHI
Original Assignee
Henkel Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Henkel Corporation filed Critical Henkel Corporation
Publication of WO2012115701A2 publication Critical patent/WO2012115701A2/en
Publication of WO2012115701A3 publication Critical patent/WO2012115701A3/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L21/6836—Wafer tapes, e.g. grinding or dicing support tapes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/20—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive itself
    • C09J2301/208—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive itself the adhesive layer being constituted by at least two or more adjacent or superposed adhesive layers, e.g. multilayer adhesive
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2423/00—Presence of polyolefin
    • C09J2423/006—Presence of polyolefin in the substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
    • H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L2221/68327—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support used during dicing or grinding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
    • H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L2221/68377—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support with parts of the auxiliary support remaining in the finished device
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/28—Structure, shape, material or disposition of the layer connectors prior to the connecting process
    • H01L2224/29—Structure, shape, material or disposition of the layer connectors prior to the connecting process of an individual layer connector
    • H01L2224/29001—Core members of the layer connector
    • H01L2224/2901—Shape
    • H01L2224/29016—Shape in side view
    • H01L2224/29018—Shape in side view comprising protrusions or indentations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/28—Structure, shape, material or disposition of the layer connectors prior to the connecting process
    • H01L2224/29—Structure, shape, material or disposition of the layer connectors prior to the connecting process of an individual layer connector
    • H01L2224/29001—Core members of the layer connector
    • H01L2224/29099—Material
    • H01L2224/2919—Material with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32225—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H01L2224/8319—Arrangement of the layer connectors prior to mounting
    • H01L2224/83191—Arrangement of the layer connectors prior to mounting wherein the layer connectors are disposed only on the semiconductor or solid-state body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H01L2224/838—Bonding techniques
    • H01L2224/8385—Bonding techniques using a polymer adhesive, e.g. an adhesive based on silicone, epoxy, polyimide, polyester
    • H01L2224/83855—Hardening the adhesive by curing, i.e. thermosetting
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/93—Batch processes
    • H01L2224/94—Batch processes at wafer-level, i.e. with connecting carried out on a wafer comprising a plurality of undiced individual devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L24/28—Structure, shape, material or disposition of the layer connectors prior to the connecting process
    • H01L24/29—Structure, shape, material or disposition of the layer connectors prior to the connecting process of an individual layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L24/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L24/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/00013—Fully indexed content

Definitions

  • the present invention relates to multilayered adhesive films that include a support layer, a first adhesive layer on or over the support layer, and a second adhesive layer abutting the first adhesive layer. At least one of the abutting surfaces of the first and second adhesive layers has a first profile and a second profile, respectively.
  • the first and/or second profiles are each independently selected such that the peel strength between the first and second adhesive layers is less than that of a comparative multilayered adhesive film that is free of the first and second profiles.
  • the multilayered adhesive films of the present invention may be used as dicing die attach films.
  • a multilayered adhesive film which: retains an article or ware in place during initial processing steps; and is then separable so as to allow processed portions of the ware to be adhered to a separate substrate in one or more subsequent processing steps.
  • a semiconductor wafer e.g., a silicon wafer
  • the dicing die attach film typically includes a substrate layer, a pressure sensitive adhesive layer on the substrate layer, and a die attach film on the pressure sensitive layer.
  • the semiconductor wafer may be optionally polished and/or thinned (e.g., by grinding), followed by cutting or dicing of the wafer into smaller chips, which are separately attached to the substrate of the dicing die attach film.
  • the dicing step typically results in the formation of dicing lanes that are free, down to the substrate layer of wafer material, dicing die attach adhesive and pressure sensitive adhesive.
  • the diced chips, which are separated from each other by intersecting dicing lanes, are then removed from (e.g., picked-up off of) the dicing die attach film in such a way that each chip retains die attach adhesive thereunder.
  • the pressure sensitive adhesive remains adhered to the substrate of the dicing die attach film.
  • the chips are then adhered to a separate substrate, such as, a semiconductor device by means of the die attach adhesive retained thereunder.
  • a separate substrate such as, a semiconductor device
  • adhesion between the pressure sensitive adhesive and the die attach adhesive is typically reduced by hardening or curing the pressure sensitive adhesive. Curing (e.g., crosslinking) of the pressure sensitive adhesive is usually conducted after initial processing steps, such as, grinding and/or polishing of the wafer, and prior to the pick-up step (e.g., after the dicing step).
  • Curing may be achieved by exposing the pressure sensitive adhesive to elevated temperature and/or actinic radiation, depending on whether the pressure sensitive adhesive is thermally and/or photo-polymerizable / curable. Curing of the pressure sensitive adhesive may be less than uniform, resulting in variable reduction in adhesion between the pressure sensitive adhesive and the die attach adhesive. Variable reduction in adhesion may result in inadequate separation of the die attach adhesive from the underlying pressure sensitive adhesive during the pick-up step. For example, during the pick-up step, chips may separate from the die attach adhesive and/or some of the pressure sensitive adhesive material may come up with the die attach film, in each case resulting in reduced or no adhesion of the chips to the semiconductor device.
  • a multilayered adhesive film comprising:
  • said first surface of said first adhesive layer has a first profile
  • said second surface of said second adhesive layer has a second profile, further wherein said first profile and said second profile are each independently selected such that,
  • said peel strength is less than said comparative peel strength.
  • an assembly comprising:
  • a separate article e.g., a sheet or wafer, such as, a silicon wafer having a second surface that is in adhesive contact with the first surface of the second adhesive layer of the multilayered adhesive film.
  • molecular weights are determined by gel permeation
  • (meth)acrylate and similar terms, such as “esters of (meth)acrylic acid” means acrylates and/or methacrylates.
  • polymer is meant to refer to both homopolymers, i.e., polymers made from a single monomer species, and copolymers, i.e., polymers made from two or more monomer species.
  • actinic radiation means
  • electromagnetic radiation that is capable of initiating free radical polymerization of a composition that includes radically polymerizable ethylenic unsaturation, and includes, but is not limited to, infrared light, visible light, ultraviolet light, electron beam radiation, x- rays, and concurrent and/or sequential combinations thereof.
  • Figure 1 is a representative sectional view of a multilayered adhesive film according to the present invention.
  • Figure 2 is a representative exploded sectional view of a multilayered adhesive film according to the present invention, in which the first surface of the first adhesive layer thereof has a first profile;
  • Figure 3 is a representative exploded sectional view of a multilayered adhesive film according to the present invention, in which the second surface of the second adhesive layer thereof has a second profile;
  • Figure 4(a) is a representative sectional view of a comparative multilayered adhesive film that is free of first and second profiles at the adhesive interface between the first and second adhesive layers;
  • Figure 4(b) is a representative exploded sectional view of the comparative multilayered adhesive film of Figure 4(a);
  • Figures 5(a) through 5(h) are representative partial perspective views of microstructures having various shapes from which the first and second profiles may be selected;
  • Figure 6 is a representative partial perspective view of a profile that includes neighboring elevated points and neighboring points of reduced elevation;
  • Figure 7 is a representative sectional view of an assembly according to the present invention that includes the multilayered adhesive film of the present invention and a separate article in adhesive contact with the second adhesive layer thereof;
  • Figure 8(a) is a representative sectional view of the assembly of Figure 6, in which a dicing lane has been formed therein;
  • Figure 8(b) is a representative sectional view of the assembly of Figure 8(a), in which a portion of a chip having a portion of the second adhesive layer adhered thereto is picked-up and separated from the first adhesive layer;
  • Figure 8(c) is a representative sectional view of the chip of Figure 8(b) that has been adhesively contacted with a separate substrate.
  • Multilayered adhesive film 1 includes a support layer 1 1 , having a first adhesive layer 14 thereon, and a second adhesive layer 17 on the first adhesive layer.
  • Support layer 1 1 has a first surface 20 and a second surface 21 that are opposed from each other (e.g., face substantially away from each other).
  • First adhesive layer 14 has a first surface 26 and a second surface 23 that are opposed from each other (e.g., face substantially away from each other).
  • Second adhesive layer 17 has a first surface 32 and a second surface 29 that are opposed from each other (e.g., face
  • second surface 23 of first adhesive layer 14 is in adhesive contact with first surface 20 of support layer 1 1.
  • adhesive contact between the second surface of the first adhesive layer and the first surface of the support layer means: (i) direct adhesive contact therebetween; or (ii) indirect adhesive contact therebetween due to a separate layer or film (e.g., a separate adhesive layer or film) being interposed therebetween.
  • the second surface of the first adhesive layer and the first surface of the support layer are in direct adhesive contact with each other.
  • First surface 26 of first adhesive layer 14 and second surface 29 of second adhesive layer 17 are in adhesive contact with each other, and have a peel strength therebetween.
  • first surface of the first adhesive layer and the second surface of the second adhesive layer are in direct adhesive contact with each other.
  • First surface 32 of second adhesive layer 17 defines an exterior adhesive surface 44 (e.g., an exterior upper adhesive surface 44) of multilayered adhesive film 1.
  • Second surface 21 of support layer 1 1 defines an exterior support surface 41 (e.g., an exterior lower support surface 41) of multilayered adhesive film 1.
  • first surface 26 of first adhesive layer 14 has a first profile 35; and/or second surface 29 of second adhesive layer 17 has a second profile 38. See, for example, Figures 2 and 3.
  • the adhesive interface 47 between the first 14 and second 17 adhesive layers has a profiled interface 50. See, for example, Figure 1.
  • the first (e.g., 35) and second (e.g., 38) profiles are each independently selected such that the peel strength between the first (e.g., 14) and second (e.g., 17) adhesive layers, of the multilayered film according to the present invention, is less than the comparative peel strength between the first and second adhesive layers of a comparative multilayered adhesive film that is free of the first profile and free of the second profile.
  • the comparative multilayered film has a support layer, first adhesive layer, and second adhesive layer; each having the same composition as the multilayered film according to the present invention.
  • the comparative multilayered film is fabricated under substantially the same conditions (e.g., pressure and temperature) as that of the
  • the comparative multilayered film has a comparative peel strength between the first and second adhesive layers thereof.
  • comparative multilayered adhesive film ⁇ includes: a first layer 1 1 having a first surface 20 and a second surface 21 that are opposed from each other; a first adhesive layer 14' having a first surface 26' and a second surface 23 that are opposed from each other; and a second adhesive layer 17' having a first surface 32 and a second surface 29' that are opposed from each other.
  • Second surface 23 of first adhesive layer 14' and first surface 20 of support layer 1 1 are in adhesive contact with each other.
  • Second surface 29' of second adhesive layer 17' and first surface 26' of first adhesive layer 14' are in adhesive contact with each other.
  • First surface 26' of first adhesive layer 14' is substantially free of a first profile (e.g., free of first profile 35), and second surface 29' of second adhesive layer 17' is substantially free of a second profile (e.g., free of second profile 38).
  • the adhesive interface 47' between the first 14' and second 17' adhesive layers of comparative multilayered adhesive film 1 ' is substantially free of a profiled interface therebetween (e.g., free of profiled interface 50).
  • the support layer 1 1 , first adhesive layer 14', and second adhesive layer 17' of comparative multilayered adhesive film each have substantially the same compositions and dimensions (e.g., thickness) as the support layer 1 1 , first adhesive layer 14, and second adhesive layer 17 of the multilayered adhesive film 1 according to the present invention.
  • the comparative peel strength between the first and second adhesive layers of a comparative multilayered adhesive film may vary widely, depending, for example, on the compositions of the adhesive layers and whether the first adhesive layer is at least partially cured.
  • a comparative multilayered adhesive film has a comparative peel strength (or adhesive force) (between the first and second adhesive layers thereof) that is from 1 1.6 Newtons per meter (N/M) to 38.6 N/M (30 grams force per inch (gF/inch) to 100 gF/inch), or from 1 1.6 N/M to 30.9 N/M (30 gF/inch to 80 gF/inch), or from 1 1.6 N/M to 23.2 N/M (30 gF/inch to 60 gF/inch), as determined at room temperature, a 180° peeling value, at a peeling speed of 305 mm / minute (12 inches / minute).
  • N/M comparative peel strength
  • the multilayered adhesive films according to the present invention typically have a peel strength (between the first and second adhesive layers) that is at least 50 percent less than the comparative peel strength (between the first and second adhesive layers) of a comparative multilayered adhesive film.
  • the multilayered adhesive films according to the present invention may have a peel strength (between the first and second adhesive layers) that is at least 60 percent less than, or at least 70 percent less than the comparative peel strength (between the first and second adhesive layers) of a comparative multilayered adhesive film.
  • the reduction in the peel strength between the first and second adhesive layers of the multilayered adhesive films according to the present invention, relative to the peel strength between the first and second adhesive layers of a comparative multilayered adhesive film, is typically less than 100% (i.e., the peel strength typically is not reduced by 100%).
  • the reduction in the peel strength between the first and second adhesive layers of the multilayered adhesive films according to the present invention, relative to the peel strength between the first and second adhesive layers of a comparative multilayered adhesive film typically has an upper limit of 99%, or 95%, or 90%, or 85%.
  • the peel strength between the first and second adhesive layers of the multilayered adhesive films according to the present invention may be reduced by from 50% to 99%, or from 60% to 95%, or from 60% to 90%, or from 70% to 85%, relative to the peel strength between the first and second adhesive layers of a comparative multilayered adhesive film.
  • the peel strength between the first and second adhesive layers of multilayered adhesive films according to the present invention may vary widely, depending, for example, on the compositions of the adhesive layers and whether the first adhesive layer is at least partially cured.
  • multilayered adhesive films according to the present invention have a peel strength (between the first and second adhesive films thereof) that is from 0.39 N/M to 9.65 N/M (1 gF/inch to 25 gF/inch), or from 0.58 N/M to 7.72 N/M (1.5 gF/inch to 20 gF/inch), or from 0.77 N/M to 5.79 N/M (2 gF/inch to 15 gF/inch), as determined at room temperature, a 180° peeling value, at a peeling speed of 305 mm / minute (12 inches / minute.
  • the peel strength between the first adhesive layer and the support layer of the multilayered adhesive films according to the present invention is greater than the peel strength between the first and second adhesive layers, such that when the first and second adhesive layers are separated from each other, the first adhesive layer and the support layer remain substantially adhered to each other.
  • the peel strength (or adhesive force) between the first adhesive layer and the support layer of the multilayered adhesive films according to the present invention is from 78 N/M to 390 N/M (200 gF/inch to 1000 gF/inch), or from 195 N/M to 312 N/M (500 gF/inch to 800 gF/inch), as determined at room temperature, a 90° peeling value, at a peeling speed of 305 mm / minute (12 inches / minute).
  • a separate article e.g., a silicon wafer
  • the peel strength between the separate article and the second adhesive layer is greater than the peel strength between the first and second adhesive layers, such that when the first and second adhesive layers are separated from each other, the separate article and the second adhesive layer remain substantially adhered to each other.
  • the first surface (e.g., 26) of the first adhesive layer (e.g., 14) has a first profile (e.g., 35); and/or the second surface (e.g., 29) of the second adhesive layer (e.g., 17) has a second profile (e.g., 38).
  • the first surface (e.g., 26) of the first adhesive layer (e.g., 14) has a first profile (e.g., 35); and the second surface (e.g., 29) of the second adhesive layer (e.g., 17) is free of the second profile (e.g., 38).
  • the first profile and the second profile of the multilayered adhesive film of the present invention each independently and typically, include a plurality of microstructures that may have substantially the same shapes or different shapes.
  • the first profile and the second profile each independently include a plurality of
  • microstructures independently having a shape selected from conical shapes, pyramidal shapes, ridges, channels, rectangular shapes, spheroidal shapes, oval shapes, conical shapes, irregular shapes, and combinations of two or more thereof.
  • microstructures of the first profile 35 having various shapes are depicted on first surface 26 of first adhesive layer 14.
  • the various microstructure shapes are depicted in Figures 5(a) through 5(h) as residing substantially on first surface 26 of first adhesive layer 14.
  • the microstructures are believed in actuality to reside both within and above first surface 26 of first adhesive layer 14, and correspondingly to also define first surface 26.
  • the profile 38 of second surface 29 of second adhesive layer 17 may also or alternatively include the various microstructure shapes depicted in and as described with reference to Figures 5(a) through 5(h).
  • First profile 35 may include microstructures having conical shapes 53, as depicted in Figure 5(a).
  • First profile 35 may include microstructures having pyramidal shapes 56, as depicted in Figure 5(b).
  • first profile 35 may include microstructures having ridges 59 and/or channels 62.
  • First profile 35 may include microstructures having spheroidal (including hemispheroidal) shapes 65, as depicted in Figure 5(d).
  • first profile 35 may include microstructures having oval (e.g., elliptical) shapes 68.
  • first profile 35 may include microstructures having rectangular shapes 71 (e.g., recta-tubular shapes, including square tubular shapes).
  • First profile 35 may include microstructures having cylindrical shapes 74, as depicted in Figure 5(g).
  • first profile 35 may include microstructures having irregular shapes 77.
  • the first and second profiles may each independently include microstructures having two or more of the recited and representatively depicted shapes.
  • microstructures of the first and second profiles each typically and
  • first profile and the second profile each independently have a plurality of elevated points, and the first profile and the second profile each independently have an average distance between neighboring pairs of the elevated points that is typically greater than or equal to 10 ⁇ and less than or equal to 300 ⁇ , for example, greater than or equal to 25 ⁇ and less than or equal to 250 ⁇ .
  • first profile 35 of first surface 26 of first adhesive layer 14 is depicted as including
  • microstructures having conical shapes 53, each having or defining an elevated point 80.
  • a neighboring pair of elevated points 83 has a distance 86 therebetween. Comparing a plurality of distances 86 between a plurality of neighboring pairs of elevated points 83 provides an average distance between neighboring pairs of the elevated points.
  • microstructures of the first and second profiles each typically and independently, have or define a plurality of points or reduced elevation (that are vertically lower relative to the plurality of elevated points).
  • Each point of reduced elevation typically has at least one neighboring point or reduced elevation, and thus, define a plurality of neighboring pairs of points of reduced elevation.
  • the average distance between neighboring pairs of points of reduced elevation may be quantified, for example, by means of micrographic (e.g., photomicrographic) analysis of the profiled surface.
  • the first profile and the second profile each independently have a plurality of points of reduced elevation, and the first profile and the second profile each independently have an average distance between neighboring pairs of the points of reduced elevation that is typically greater than or equal to 10 ⁇ and less than or equal to 300 ⁇ , for example, greater than or equal to 25 ⁇ and less than or equal to 250 ⁇ .
  • first profile 35 of first surface 26 of first adhesive layer 14 is depicted as including microstructures having conical shapes 53, each having or defining a point of reduced elevation 89.
  • a neighboring pair of points of reduced elevation 92 has a distance 95 therebetween. Comparing a plurality of distances 95 between a plurality of neighboring pairs of points of reduced elevation 92 provides an average distance between neighboring pairs of the points of reduced elevation.
  • the first and second profiles may each be independently formed by methods including, for example, chemical etching, surface cutting (or engraving), and/or compressive imprinting (e.g., stamping).
  • an actinic radiation curable adhesive layer such as, the first adhesive layer
  • chemical etching may be used to profile the surface.
  • a mask is typically positioned on or over the surface to be profiled, and actinic radiation (e.g., ultraviolet light) is applied through the mask, but only so as to result in polymerization to a limited depth below the surface (the limited depth being less than the total thickness of the adhesive layer).
  • actinic radiation e.g., ultraviolet light
  • the mask is removed, and the surface is developed by exposure to a suitable solvent that removes a non-cross-linked polymer from certain (e.g., unexposed) surface regions, thus, resulting in a profiled adhesive surface.
  • Surface cutting may be achieved by impinging a high-pressure liquid jet (e.g., water jet, optionally including abrasive media), or a beam of high energy electromagnetic radiation (e.g., a high energy laser) onto the adhesive surface, so as to remove portions of the adhesive polymer material (e.g., by localized abrasion and/or localized pyrolization).
  • a high-pressure liquid jet e.g., water jet, optionally including abrasive media
  • a beam of high energy electromagnetic radiation e.g., a high energy laser
  • the first and second profiles are each independently formed by compressive imprinting (e.g., stamping or embossing) of the adhesive surface.
  • compressive imprinting e.g., stamping or embossing
  • a template having a negative representation or form of the desired profile on a surface thereof is pressed against and/or into the adhesive surface under conditions of elevated pressure and optionally elevated temperature.
  • negative representation or form with regard to the template means that depressions on the template surface form elevated points on the profiled adhesive surface, and elevated points on the template surface form depressions within the profiled adhesive surface.
  • the template may be fabricated from any suitable material, provided it is harder than the adhesive surface against / into which it is compressed.
  • the template may be fabricated from, one or more metals, ceramics (e.g., glass), and/or cross-linked polymers.
  • the template may be substantially solid, or it may be in the form of a mesh or screen.
  • the template used to form the first profile and/or the second profile is a screen or mesh fabricated from metal.
  • the template is a metal screen or mesh from a particulate sieve, having a screen mesh size (or designation) that is greater than or equal to 10 ⁇ and less than or equal to 300 ⁇ , for example, greater than or equal to 25 ⁇ and less than or equal to 250 ⁇ (e.g., selected from 25 ⁇ mesh, 55 ⁇ mesh, and/or 250 ⁇ mesh screens).
  • the support layer of the multilayered adhesive film of the present invention may be fabricated from any suitable material, such as paper, metal (e.g., metal foil), polymeric materials, ceramics (e.g., glass, such as glass sheet or woven fiber glass mat), and combinations (including blends and/or multiple layers) thereof.
  • the support layer may include a single layer or multiple layers (e.g., 2 or more layers).
  • Multilayered support layers may be fabricated by art-recognized methods, such as, coextrusion and/or lamination. Adjacent layers of the multilayered support layer may abut each other directly or have an adhesive (or tie) layer interposed therebetween.
  • Each layer of the support layer, that includes one or more polymeric materials may independently be subjected to uniaxial stretching (or drawing), biaxial stretching, or be free of uniaxial and biaxial stretching.
  • the support layer is composed of a single layer.
  • the first surface (e.g., first surface 20) of the support layer may be subjected to art-recognized surface treatments for purposes including, but not limited to, improving adhesion to the first adhesive layer (e.g., 14).
  • surface treatments to which the first surface of the support layer may be subjected include, but are not limited to, exposure acids, such as, chromic acid, exposure to ozone, flame treatment, exposure to one or more ionized gasses, and combinations thereof.
  • the first surface (e.g., 20) of the support layer may be defined by a coating, such as a silane functional coating.
  • Coatings may be applied to the support layer by art-recognized methods, such as, spraying, dipping, and curtain coating.
  • the second surface (e.g., 21) of the support layer may be subjected to the same treatments (e.g., adhesion promoting treatments, including coatings) as the first surface thereof.
  • the second surface of the support layer is not subjected to adhesion promoting treatments.
  • the support layer includes at least one layer that includes a polymer, which may be selected from thermoplastic polymers, thermoset polymers, and combinations thereof.
  • a polymer which may be selected from thermoplastic polymers, thermoset polymers, and combinations thereof.
  • polymers from which the support layer may be fabricated but are not limited to, polyolefms such as low density polyethylene, linear polyethylene, linear low density polyethylene, middle density polyethylene, high density polyethylene, super low density polyethylene, random and block copolymerized
  • polyolefins such as, copolymers having monomer residues selected from two or more of ethylene, propylene, butene, pentene and hexene, ethylene/vinyl acetate copolymer, ionomer resins, ethylene/(meth)acrylic acid copolymer, ethylene/(meth)acrylic acid ester (random or alternate) copolymer, polyurethanes, polyesters such as, polyethylene terephthalate, and polyethylene naphthalate, polycarbonates, polyimides, polyamides, polyetheretherketones, polyphenylsulfide,; fluorine-containing polymers, polyvinyl chloride, polyvinylidene chloride, cellulose resins, silicone resins, and combinations thereof.
  • the support layer is composed of a single layer, includes a polyolefin, such as polyethylene, and has a melting point of from 60°C to 120°C (e.g., about 70°C).
  • Each layer of the support layer may independently include one or more additives.
  • additives that may be independently included in each layer (e.g., each polymeric layer) of the support layer include, but are not limited to, thermal stabilizers, ultraviolet light stabilizers, pigments, dyes, antistatic agents, plastisizers, and
  • the first adhesive layer (e.g., 14) is at least partially curable by exposure to actinic radiation (e.g., ultraviolet light, X-rays, and/or electron beam).
  • actinic radiation e.g., ultraviolet light, X-rays, and/or electron beam.
  • the support layer e.g., 1 1
  • the support layer in an embodiment is substantially transparent to actinic radiation (i.e., it has a high transmission of actinic radiation therethrough).
  • actinic radiation impinged upon the second surface (e.g., 21) of the support layer (e.g., 1 1) passes through the body or core of the support layer, out through the first surface (e.g., 20) of the support layer, and into the first adhesive layer (e.g., 14), so as to result in at least partial curing (e.g., photo-polymerization) of the first adhesive layer.
  • the support layer may have any suitable thickness, provided it is capable of supporting and withstanding operations that the upper layers may be subjected to (e.g., chip dicing operations, as will be discussed further herein).
  • the support layer typically has a thickness of from 5 ⁇ to 200 ⁇ , or from 10 ⁇ to 150 ⁇ , or from 20 ⁇ to 100 ⁇ .
  • the first adhesive layer may include a single layer or multiple layers (e.g., 2 or more layers). When the first adhesive layer includes two or more layers, each layer may have the same or different compositions. Typically, the first adhesive layer is composed of a single layer.
  • the first adhesive layer is formed on the first surface of the support layer, by art- recognized methods.
  • the first adhesive layer may be laminated or extruded onto the first surface of the support layer.
  • the combination of the support layer and the first adhesive layer which may be referred to as a tape, may be stored for a period of time, after which the second adhesive layer is applied to the first adhesive layer.
  • a release film may be applied to the first surface of the first adhesive layer, and the combination of the support layer, the first adhesive layer, and the release film are rolled up. The release film prevents fusion between the first surface of the first adhesive layer and the second surface of the support layer when the combination is formed into a roll. The release film is removed before the second adhesive layer is formed on the first adhesive layer.
  • the first adhesive layer typically includes a self-adhesive material, such as a pressure sensitive adhesive material, and may be a thermoplastic first adhesive layer or a curable first adhesive layer (e.g., curable by exposure to elevated temperature and/or actinic radiation).
  • the first adhesive layer may include polymers selected from, but not limited to, rubbers (including synthetic and/or natural rubbers), acrylic polymers, silicone polymers, polyvinyl ethers, and combinations of two or more thereof.
  • Acrylic polymers that may be included in the first adhesive layer typically include residues of esters of (meth)acrylic acid, such as Ci-C2 0 -(meth)acrylate monomers, including linear or branched C3-C 2 o-(meth)acrylate monomers, cyclic C 3 ⁇ C 2 o- (meth)acrylate monomers, and aromatic C5-C i4-(meth)acrylate monomers.
  • esters of (meth)acrylic acid are selected from Ci-C 2 o-alkyl(meth)acrylates.
  • Ci-C 20 -alkyl (meth)acrylates include, but are not limited to, methyl (mefh)acrylate, ethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxypropyl (mefh)acrylate, isopropyl (mefh)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate and 3,3,5-trimethylcyclohexyl (meth)acrylate.
  • cycloalkyl (meth)acrylates include, but are not limited to,
  • cyclopropyl(meth)acrylate cyclobutyl(meth)acrylate, cyclopentyl(meth)acrylate, cyclohexyl(meth)acrylate, cycloheptyl(meth)acrylate, and isobornyl(meth)acrylate.
  • esters of (meth)acrylic acid may optionally be copolymerized with one or more monomers having active hydrogen groups, such as, carboxylic acid groups, phosphoric acid groups, sulfonic acid groups, thiol groups, and/or hydroxyl groups.
  • Copolymerizable monomers having active hydrogen groups are typically present in amounts of less than or equal to 40 percent by weight, based on total weight of monomers.
  • copolymerizable monomers containing carboxylic acid groups include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and acid anhydride monomers such as, maleic anhydride, and itaconic anhydride.
  • acrylic acid methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and acid anhydride monomers such as, maleic anhydride, and itaconic anhydride.
  • copolymerizable monomer containing a phosphoric acid group is 2-hydroxyethylacryloyl phosphate.
  • copolymerizable monomers that include a sulfonic acid group include, but are not limited to, styrenesulfonic acid, allylsulfonic acid, 2- (meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.
  • copolymerizable monomers containing hydroxyl groups include, but are not limited to, 2- hydroxyethyl(meth)acrylate, 2-hydiOxypropyl(mefh)acrylate, 4-hydroxybutyl
  • (meth)acrylate 6-hydroxyhexyl(meth)acrylate, 8-hydroxyoctyl(meth)acrylate, 10- hydroxydecyl(meth)acrylate, 12-hydroxylauryl(meth)acrylate, and (4- hydroxylmethylcyclohexyl)methyl(meth)acrylate.
  • esters of (meth)acrylic acid may further optionally be copolymerized with polyfunctional monomers, for purposes of increasing the crosslink density of the resulting acrylic polymer.
  • polyfunctional monomers include, but are not limited to, hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol
  • di(meth)acrylate trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. If present, such polyfuncational monomers are present in amounts of less than or equal to 10 percent by weight, for example less than or equal to 5 percent by weight, abased on total monomer weight.
  • the molecular weight of the acrylic polymer of the first adhesive layer may vary widely, and is generally selected such that the first adhesive layer has desirable adhesive qualities.
  • the number average molecular weight of the acrylic polymer is at least 200,000 and less than or equal to 4,000,000 (e.g., from 300,000 to 3,500,000, or from 400,000 to 3,000,000).
  • the first adhesive layer may be a curable first adhesive layer, that is curable (i.e., cross-linkable) by exposure to elevated temperature and/or actinic radiation. Curing the curable first adhesive layer may be desirable for reasons including, but not limited to, reducing the adhesive properties of the first adhesive layer. Thermal curing of the first adhesive layer may be achieved by including one or more cross-linking agents that become reactive (e.g., by loss of a blocking or capping group) with active hydrogen functionality (e.g., hydroxyl, thiol, primary amine, secondary amine, and/or carboxylic acid groups) of the polymer.
  • cross-linking agents that become reactive (e.g., by loss of a blocking or capping group) with active hydrogen functionality (e.g., hydroxyl, thiol, primary amine, secondary amine, and/or carboxylic acid groups) of the polymer.
  • cross-linking agents examples include, but are not limited to, polyisocyanates, polyoxiranes (i.e., polyepoxides), and melamines.
  • Cross-linking agents are typically used in amounts of less than 10 percent by weight, such as, from 0.1 to 5 percent by weight, based on the total weight of polymer and cross-linking agent.
  • the first adhesive layer may alternatively be curable by exposure to actinic radiation (e.g., ultraviolet light, electron beam, and/or X-rays).
  • actinic radiation curable first adhesive layer may include: a high molecular weight polymer that is free of ethylenic unsaturation (e.g., an acrylic polymer as described previously herein); an ethylenically unsaturated oligomer, and/or ethylenically unsaturated monomer; and an actinic radiation activated initiator (e.g., a photoinitiator).
  • the actinic radiation curable first adhesive layer may include: a polymer (e.g., an acrylic polymer) having pendent and/or terminal ethylenic unsaturation; optionally, an ethylenically unsaturated oligomer and/or ethylenically unsaturated monomer; and an actinic radiation activated initiator (e.g., a photoinitiator).
  • a polymer e.g., an acrylic polymer having pendent and/or terminal ethylenic unsaturation
  • an ethylenically unsaturated oligomer and/or ethylenically unsaturated monomer e.g., a photoinitiator
  • Pendent and/or terminal ethylenic unsaturation may be introduced into an acrylic polymer by art-recognized methods.
  • an acrylic polymer having pendent and/or terminal active hydrogen groups e.g., hydroxyl, thiol, primary amine, secondary amine, or carboxylic acid groups
  • pendent and/or terminal active hydrogen groups e.g., hydroxyl, thiol, primary amine, secondary amine, or carboxylic acid groups
  • (meth)acrylic monomers that are reactive with such active hydrogen groups, such as oxirane functional (meth)acrylates (e.g., glycidol (meth)acrylate) and isocyanate functional (meth)acrylates (e.g., methacryloyl isocyanate).
  • the ethylenically unsaturated oligomer and ethylenically unsaturated monomer components may each independently have at least one (e.g., two or more) ethylenically unsaturated groups.
  • ethylenically unsaturated monomer components include, but are not limited to, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol
  • ethylenically unsaturated oligomers include, but are not limited to, those terminated with (meth)acrylate groups, and having backbones selected from urethane, polyether, polyester, polycarbonate, and/or polybutadiene. Ethylenically unsaturated oligomers may have molecular weights from 100 to 30,000.
  • Photoinitiators that may be used in the actinic radiation curable first adhesive layer include those known to the skilled artisan.
  • Examples of photoinitiators include, but are not limited to: a-ketol compounds, such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2- propyl)ketone, a-hydroxy-a, a'-dimethylacetophenone, 2-methyl-2- hydroxypropiophenone, and 1 -hydroxy cyclohexyl phenyl ketone; acetophenone
  • benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'- dimethyl-4-methoxybenzophenone
  • thioxanthone compounds such as thioxanthone, 2- chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone
  • the amount of photoinitiator(s) present is typically selected so as to result in a combination of: a desired level of cure (e.g., as measured by increased surface hardness); within a limited amount of time; and with exposure to a certain level of actinic radiation for a given amount of time.
  • a desired level of cure e.g., as measured by increased surface hardness
  • the photoinitiator is present in an amount of less than or equal to 20 percent by weight (e.g., from 0.05 to 20 percent by weight, based on total weight of resin components).
  • Each layer of the first adhesive layer may independently include one or more additives.
  • additives that may be independently included in each layer (e.g., each polymeric layer) of the first adhesive layer include, but are not limited to, thermal stabilizers, ultraviolet light stabilizers (e.g., with first adhesive layers that are not photopolymerizable), pigments, dyes, antistatic agents, plastisizers, and combinations thereof.
  • the first adhesive layer may have any suitable thickness (e.g., such that it may retain a profile imparted upon the first surface thereof).
  • the first adhesive layer has a thickness that is less than or equal to 100 ⁇ , such as, from 1 to 50 ⁇ , or 2 to 30 ⁇ , or 5 to 25 ⁇ .
  • the second adhesive layer may include a single layer or multiple layers (e.g., 2 or more layers). When the second adhesive layer includes two or more layers, each layer may have the same or different compositions. Typically, the second adhesive layer is composed of a single layer.
  • the second adhesive layer may be formed onto at least a portion of the first adhesive layer by art-recognized methods.
  • the second adhesive layer may be laminated or extruded onto at least a portion of the first surface of the first adhesive layer.
  • the second adhesive layer is laminated onto at least a portion of the first surface of the first adhesive layer.
  • the first profile is imparted onto (or into) the first surface of the first adhesive layer; and/or the second profile is imparted onto (or into) the second surface of the second adhesive layer.
  • the methods by which the first and second profiles are each independently imparted onto the respective adhesive surface include, but are not limited to, those discussed previously herein.
  • Imparting the second profile onto/into the second surface of the second adhesive film may be conducted while the second adhesive layer is retained on a transfer film (or carrier film).
  • a transfer film or carrier film
  • the second profile is imparted/formed onto/into the second surface of the transfer film supported second adhesive layer.
  • the profiled second adhesive layer may be separated from the transfer film and then adhesively contacted with the first surface of the first adhesive layer.
  • the profiled second adhesive layer may be adhesively contacted with the first surface of the first adhesive layer, while the transfer film is in separable (or reversible) adhesive contact with the first surface of the second adhesive layer.
  • the transfer film may be retained in contact with the first surface of the second adhesive layer until it is desired to bring the first surface of the second adhesive layer into adhesive contact with a separate article, such as, a silicon wafer.
  • the second adhesive layer may be adhesively contacted with the first surface (having a first profile) of the first adhesive layer, while a transfer film is in separable (or reversible) adhesive contact with the first surface of the second adhesive layer.
  • the transfer film may be optionally retained in contact with the first surface of the second adhesive layer until, for example, a separate article, such as, a silicon wafer, is brought into adhesive contact with the first surface of the second adhesive layer.
  • the composition of the second adhesive layer is typically selected such that, with a separate article (e.g., a silicon wafer) retained in adhesive contact with the first surface thereof, the second surface thereof is capable of subsequently adhering to a separate substrate (e.g., a semiconductor device) after separation from the first adhesive layer.
  • the second adhesive layer typically includes a thermoplastic polymer and/or a thermoset polymer.
  • the composition of the second adhesive layer is selected such that the first surface thereof may be adhesively contacted with a separate article (e.g., a silicon wafer) at a temperature of less than or equal to 70°C (e.g., at room temperature, or about 25°C).
  • Classes of thermoplastic polymers that may be included in the second adhesive layer include, but are not limited to: saturated polyesters; polyurethanes; polyamides (e.g., nylon polymers); polyimides; silicone polymers; elastomeric polymers, such as rubber polymers, including natural and/or synthetic rubber polymers, such as functionally terminated butadiene acrylonitrile rubbers, including, for example, epoxy-terminated butadiene acrylonitrile rubbers (ETBN's), amino-terminated butadiene acrylonitrile rubbers (ATBN's), carboxy-terminated butadiene acrylonitrile rubbers (CTBN's), and hydroxy-terminated butadiene acrylonitrile rubbers (HTBN's); poly(meth)acrylates; and combinations of two or more thereof.
  • Classes of thermoset polymers that may be included in the second adhesive layer include, but are not limited to, thermoset epoxy polymers, thermoset unsaturated polyesters, thermoset acrylic polymers, and thermoset
  • the second adhesive layer includes a non-elastomeric polymer and an elastomeric polymer.
  • the non-elastomeric polymer may be selected from art- recognized non-elastomeric polymers, including those classes and examples of
  • thermoplastic polymers as previously recited, such as: saturated polyesters; polyurethanes; polyamides (e.g., nylon polymers); polyimides; silicone polymers; poly(meth)acrylates; polyethers, including polyepoxides; and combinations of two or more thereof.
  • the elastomeric polymer may be selected from art-recognized elastomeric polymers, including, rubber polymers, including natural and/or synthetic rubber polymers, such as, functionally terminated butadiene acrylonitrile rubbers, including, for example, epoxy-terminated butadiene acrylonitrile rubbers (ETBN's), amino-terminated butadiene acrylonitrile rubbers (ATBN's), carboxy-terminated butadiene acrylonitrile rubbers (CTBN's), and hydroxy-terminated butadiene acrylonitrile rubbers (HTBN's); and combinations of two or more thereof.
  • EBN's epoxy-terminated butadiene acrylonitrile rubbers
  • ATBN's amino-terminated butadiene acrylonitrile rubbers
  • CBN's carboxy-terminated butadiene acrylonitrile rubbers
  • HTBN's hydroxy-terminated butadiene acrylonitrile rubbers
  • the non-elastomeric polymer is selected from
  • poly(meth)acrylates and/or polyethers such as polyepoxides
  • the elastomeric polymer is selected from one or more functionally terminated butadiene acrylonitrile rubbers, such as, epoxy-terminated butadiene acrylonitrile rubbers (ETBN's), amino-terminated butadiene acrylonitrile rubbers (ATBN's), carboxy-terminated butadiene acrylonitrile rubbers (CTBN's), and/or hydroxy-terminated butadiene acrylonitrile rubbers (HTBN's).
  • EBN's epoxy-terminated butadiene acrylonitrile rubbers
  • ATBN's amino-terminated butadiene acrylonitrile rubbers
  • CBN's carboxy-terminated butadiene acrylonitrile rubbers
  • HTBN's hydroxy-terminated butadiene acrylonitrile rubbers
  • the non-elastomeric polymer may be present in the second adhesive layer in an amount of from 5 to 95 percent by weight, or from 10 to 75 percent by weight, or from 25 to 55 percent by weight, based in each case on the total weight of non-elastomeric polymer and elastomeric polymer.
  • the elastomeric polymer may be present in the second adhesive layer in an amount of from 5 to 95 percent by weight, or from 25 to 90 percent by weight, or from 45 to 75 percent by weight, based in each case on the total weight of non- elastomeric polymer and elastomeric polymer.
  • Each layer of the second adhesive layer may independently include one or more additives.
  • additives that may be independently included in each layer (e.g., each polymeric layer) of the second adhesive layer include, but are not limited to, thermal stabilizers, ultraviolet light stabilizers, pigments, dyes, antistatic agents, plastisizers, and combinations thereof.
  • the second adhesive layer may have any suitable thickness.
  • the second adhesive layer may have a thickness of from 5 ⁇ to 100 ⁇ , or from 10 ⁇ to 50 ⁇ .
  • the present invention also relates to an assembly that includes the multilayered adhesive film of the present invention, as described above, and a separate article (e.g., a sheet or wafer, such as a semiconductor wafer) having a second surface that is in adhesive contact with the first surface of the second adhesive layer.
  • a separate article e.g., a sheet or wafer, such as a semiconductor wafer
  • adhesive contact between the second surface of the separate article and the first surface of the second adhesive layer means: (i) direct adhesive contact therebetween; or (ii) indirect adhesive contact therebetween due to a separate layer or film (e.g., a separate adhesive layer or film) being interposed therebetween.
  • the second surface of the separate article and the first surface of the second adhesive layer are in direct adhesive contact with each other.
  • assembly 3 includes a multilayered adhesive film 1 according to the present invention and a separate article 98 that is in adhesive contact with second adhesive layer 17 of multilayered adhesive film 1.
  • Separate article 98 has a first surface 101 and a second surface 104 that are substantially opposed from each other (e.g., face substantially away from each other). Second surface 104 of separate article 98 and first surface 32 of second adhesive layer 17 are in adhesive contact with each other.
  • the separate article may have any suitable shape, such as three-dimensional shapes or substantially flat shapes, such as in the form of a sheet or film.
  • the separate article is in the form of a sheet or film, and may be substantially continuous or discontinuous (e.g., in the form of a mesh or screen).
  • the separate article is in the form of a substantially continuous sheet or film.
  • the separate article may be fabricated from any suitable material, such as, thermoplastic polymers, thermoset polymers, metals, ceramics, semiconductor materials (e.g., semiconductor wafers comprising silicon), or any combination thereof.
  • the separate article is a silicon wafer (e.g., a semiconductor wafer
  • the silicon wafer may include other materials, such as, germanium, gallium arsenide, and/or silicon carbide.
  • the separate article may have a wide range of thicknesses.
  • the separate article when it is a silicon wafer, it may have a thickness of from 5 to 1000 micrometers ( ⁇ ), or from 25 to 300 ⁇ .
  • the assembly of the present invention may be formed by art-recognized methods.
  • the multilayered adhesive film is separately formed (or pre-formed), and the separate article and the second adhesive layer of the multilayered adhesive film are brought into adhesive contact with each other under conditions of elevated pressure and optionally elevated temperature.
  • the separate article is a silicon wafer
  • the silicon wafer and the second adhesive layer of the multilayered adhesive film are brought into adhesive contact with each other under an applied pressure of from 0.0125 to 1.45 pounds per square inch (psi) (86 to 9997 pascal), and a temperature of from 20 to 120°C.
  • the first surface of the separate article e.g., a silicon wafer
  • the first adhesive layer of the multilayered adhesive film is optionally subjected to a curing step.
  • the second surface of the support layer may be exposed to an actinic radiation source (e.g., a UV light source). The actinic radiation passes through the support layer and into to first adhesive layer, thus resulting in curing of the first adhesive layer.
  • an actinic radiation source e.g., a UV light source
  • the separate article is a wafer, such as, a silicon wafer
  • the assembly is typically subjected to a dicing step, after processing of the first surface of the wafer.
  • Dicing typically involves cutting the silicon wafer into a plurality of separate chip preforms that are still adhered to the support layer of the multilayered film (or dicing-die attach film).
  • the silicon wafer is subjected to an appropriate cutting method, such as, by means of, a laser or a fluid jet cutter (e.g., a water jet) that may optionally include an abrasive media.
  • Dicing of the silicon wafer results in the formation of a plurality of intersecting dicing lanes, which typically extend down through the second adhesive layer, the first adhesive layer, and optionally partially into the support layer (but not all of the way through the support layer). Dicing also results in the formation of a plurality of separate chip preforms.
  • assembly 3 of Figure 7 has been subjected to a dicing step, and includes separate chip preforms 107 having a dicing lane 1 10
  • Dicing lane 1 10 extends down to first surface 20 of support layer 1 1 of multilayered adhesive film 1 , which in Figures 8(a) and 8(b) is a dicing die attach film. While dicing lane 1 10 may optionally extend partially into support layer 1 1 , it does not extend all of the way through support layer 1 1.
  • the chip preforms are subjected to a pick-up step.
  • a pick-up tool removes a chip, that includes a diced wafer with a diced portion of the second adhesive layer attached thereunder, from the first adhesive layer.
  • the chip is then moved to and adhesively contacted to a separate substrate (e.g., a semiconductor element) by means of the second adhesive layer residing under the diced wafer.
  • the second adhesive layer may then be crosslinked and cured, for example by exposure to elevated temperature, thereby fixedly attaching the chip to the semiconductor element.
  • First adhesive layer 14 remains adhered to support layer 1 1.
  • the pickup tool generally includes an elongated arm having a terminal head that contacts first surface 101 of wafer 98 with reduced pressure (e.g., suction) therebetween.
  • the elongated arm of the pick-up tool may be attached to a linear actuator (not shown) that vertically repositions the head of the pick-up tool relative to the diced assembly 3(a).
  • the diced assembly 3(a) is usually retained, e.g., within a frame (not shown).
  • the pick-up tool next moves chip 1 13 to a separate substrate 1 16 (e.g., a semiconductor element), and brings the second surface 29 of the second adhesive layer 17 into adhesive contact with the first surface 1 19 of the separate substrate 1 16.
  • second adhesive layer 17 may optionally be subjected to a curing step.
  • the combination of chip 1 13 adhered to separate substrate 1 16 may be subjected to elevated temperature, resulting in cross-linking and cure of second adhesive layer 17, thereby, fixedly attaching chip 1 13 to separate substrate 1 16.
  • the separate substrate may be, for example, a semiconductor element, such as, a lead frame, and may include a plurality of chips 1 13 adhered thereto.
  • a separate substrate 1 16 e.g., a semiconductor element
  • chip 1 13 may be adhered to one or more underlying chips 1 13 (not shown) that are together adhered to separate substrate 1 16.
  • the peel strength (or adhesive force) between the separate article and the second adhesive layer is greater than the peel strength between the first and second adhesive layers, such that when the first and second adhesive layers are separated from each other, the separate article and the second adhesive layer remain substantially adhered to each other.
  • the peel strength (or adhesive force) between the separate article and the second adhesive layer of the multilayered adhesive films according to the present invention is from 78 N/M to 390 N/M (200 gF/inch to 1000 gF/inch), or from 195 N/M to 312 N/M (500 gF/inch to 800 gF/inch), as determined at room temperature, a 180° peeling value, at a peeling speed of 305 mm / minute (12 inches / minute).
  • the first and second profiles are each independently and additionally selected such that, increasing a distance between the separate article and the support layer, results in separation of the first surface of the first adhesive layer and the second surface of the second adhesive layer from each other. Concurrently with such separation, adhesive contact is maintained between the second surface of the first adhesive layer and the first surface of the support layer, and adhesive contact is maintained between the separate article and the first surface of the second adhesive layer.
  • diced wafer portion 98 and support 11 of chip preform 107 have a first distance 122
  • first surface 26 of first adhesive layer 14 and second surface 29 of second adhesive layer 17 (of chip 113) are separated from each other.
  • second distance 125 is greater than first distance 122. While the first and second adhesive layers are separated from each other: adhesive contact is maintained between second surface 23 of first adhesive layer 14 and first surface 20 of support layer 11 ; and adhesive contact is maintained between second surface 104 of separate article (e.g., wafer) 98 and first surface 32 of second adhesive layer 17.
  • the multilayered films of the present invention may be used in a number of applications. Typically, the multilayered films of the present invention are used in conjunction with processes where it is desirable to retain an article or ware in place during initial processing steps, and then selectively separate the ware from the multilayered film so as to allow processed portions of the ware to be adhered (by means of a retained portion of the multilayered film) to a separate substrate in one or more subsequent processing steps.
  • the multilayered film of the present invention is a dicing die attach film, which may be used in the processing of wafers, such as, silicon wafers / chips.
  • the multilayered film of the assembly is a dicing die attach film
  • the separate article thereof is a wafer, such as, a semiconductor wafer (e.g., a silicon wafer).
  • Multilayered adhesive films according to the present invention were prepared in accordance with the following description.
  • a dicing tape was obtained commercially from Denki Kagaku Kogyo Kabushiki Kaisha, under the tradename ERX-8005 dicing tape.
  • the dicing tape had a polyolefin support layer having a melting point of about 70°C, and a pressure sensitive adhesive layer thereover, composed of an ultraviolet light curable acrylic polymer.
  • Polyester wire mesh screens having dimensions of 20 cm x 20 cm were cut from sieves having mesh size designations of 25 ⁇ , 55 ⁇ , and 250 ⁇ . The sieves were obtained commercially from Filter Specialists Inc. of Indiana, USA .
  • the pressure sensitive adhesive layers of the dicing tape samples were embossed with each of the wire mesh screens at a temperature of 65°C and a pressure of 2 psi. After embossing, the wire mesh screens were separated from the pressure sensitive adhesive layer. Comparative (or control) samples of the dicing tape were not embossed with wire mesh screens.
  • Multilayered adhesive films according to the present invention were formed by laminating EASY STACK ATB-130U adhesive film (a rubberized epoxy containing film, obtained commercially from Henkel Corporation) over the pressure sensitive adhesive layer of the embossed dicing tapes, at a temperature of about 25°C and a pressure of 0.29 psi (2000 pascal). Comparative (or control) multilayered adhesive films were prepared by laminating EASY STACK ATB-130U adhesive film over the pressure sensitive adhesive layers of the dicing tape samples that had not been embossed, at a temperature of about 25°C and a pressure of 0.29 psi (2000 pascal).
  • the multilayered adhesive films according to the present invention, and the comparative multilayered adhesive films were subjected to UV light, so as to cure the pressure sensitive adhesive layers thereof.
  • the inventive and comparative multilayered adhesive films were exposed to 400 mJ/cm 2 of UV light using a Model 18672 ultraviolet light exposure system (commercially available from UVEXS Incorporated) fitted with a 385 nm UV lamp.
  • Multilayered adhesive films according to the present invention, and comparative multilayered adhesive films each having dimensions of 2.5 cm x 20 cm were evaluated for peel strength between the EASY STACK ATB- 130U layer and the UV cured pressure sensitive adhesive layer in accordance with the following description.
  • Three test samples each were evaluated using a TA.XTPlus Analyzer obtained commercially from Stable Micro Systems, Ltd, at room temperature and at a peeling speed of 305 mm / minute (12 inches / minute) to obtain 180° peel strength values.
  • the peel strength results are summarized in the following Table- 1.
  • the peel strength values are provided as: average value ⁇ standard deviation.
  • the peel strength values represent the steady-state peel strength of the samples.

Abstract

Multilayered adhesive films that include a support layer, a first adhesive layer on or over the support layer and a second adhesive layer abutting the first adhesive layer, are provided. Of the abutting surfaces of the first and second adhesive layers, the first adhesive layer has a first profile and/or the second adhesive layer has a second profile. The first and/or second profiles are each independently selected such that the peel strength between the first and second adhesive layers is reduced relative to the comparative peel strength of a comparative multilayered adhesive film that is free of the first and second profiles. The multilayered adhesive films of the present invention may be used as dicing die attach films. Also provided is an assembly that includes a separate article (e.g., a silicon wafer) adhered to the multilayered adhesive film of the present invention.

Description

MULTILAYERED ADHESIVE FILM
FIELD OF THE INVENTION
[0001] The present invention relates to multilayered adhesive films that include a support layer, a first adhesive layer on or over the support layer, and a second adhesive layer abutting the first adhesive layer. At least one of the abutting surfaces of the first and second adhesive layers has a first profile and a second profile, respectively. The first and/or second profiles are each independently selected such that the peel strength between the first and second adhesive layers is less than that of a comparative multilayered adhesive film that is free of the first and second profiles. The multilayered adhesive films of the present invention may be used as dicing die attach films.
BACKGROUND OF THE INVENTION
[0002] In certain applications it is desirable to use a multilayered adhesive film, which: retains an article or ware in place during initial processing steps; and is then separable so as to allow processed portions of the ware to be adhered to a separate substrate in one or more subsequent processing steps. With the manufacture of semiconductor devices, for example, a semiconductor wafer (e.g., a silicon wafer) is typically attached to the die attach film or layer of a dicing die attach film. The dicing die attach film typically includes a substrate layer, a pressure sensitive adhesive layer on the substrate layer, and a die attach film on the pressure sensitive layer. While adhesively attached to the dicing die attach film, the semiconductor wafer may be optionally polished and/or thinned (e.g., by grinding), followed by cutting or dicing of the wafer into smaller chips, which are separately attached to the substrate of the dicing die attach film. The dicing step typically results in the formation of dicing lanes that are free, down to the substrate layer of wafer material, dicing die attach adhesive and pressure sensitive adhesive. The diced chips, which are separated from each other by intersecting dicing lanes, are then removed from (e.g., picked-up off of) the dicing die attach film in such a way that each chip retains die attach adhesive thereunder. The pressure sensitive adhesive remains adhered to the substrate of the dicing die attach film. The chips are then adhered to a separate substrate, such as, a semiconductor device by means of the die attach adhesive retained thereunder. [0003] To enhance or ensure separation of the die attach adhesive from the underlying pressure sensitive adhesive during the pick-up step, adhesion between the pressure sensitive adhesive and the die attach adhesive is typically reduced by hardening or curing the pressure sensitive adhesive. Curing (e.g., crosslinking) of the pressure sensitive adhesive is usually conducted after initial processing steps, such as, grinding and/or polishing of the wafer, and prior to the pick-up step (e.g., after the dicing step). Curing may be achieved by exposing the pressure sensitive adhesive to elevated temperature and/or actinic radiation, depending on whether the pressure sensitive adhesive is thermally and/or photo-polymerizable / curable. Curing of the pressure sensitive adhesive may be less than uniform, resulting in variable reduction in adhesion between the pressure sensitive adhesive and the die attach adhesive. Variable reduction in adhesion may result in inadequate separation of the die attach adhesive from the underlying pressure sensitive adhesive during the pick-up step. For example, during the pick-up step, chips may separate from the die attach adhesive and/or some of the pressure sensitive adhesive material may come up with the die attach film, in each case resulting in reduced or no adhesion of the chips to the semiconductor device.
[0004] It would be desirable to develop new multilayered films that possess improved (e.g., controlled and uniform) separation between abutting adhesive layers thereof. It would be further desirable that such newly developed multilayered films could be used as dicing die attach films.
SUMMARY OF THE INVENTION
[0005] In accordance with the present invention, there is provided a multilayered adhesive film comprising:
(a) a support layer having a first surface;
(b) a first adhesive layer having a first surface and a second surface that are opposed from each other, said second surface of said first adhesive layer and said first surface of said support layer being in adhesive contact with each other; and
(c) a second adhesive layer having a first surface and a second surface that are opposed from each other, said first surface of said first adhesive layer and said second surface of said second adhesive layer being in adhesive contact with each other and having a peel strength therebetween,
wherein, at least one of,
(i) said first surface of said first adhesive layer has a first profile, and
(ii) said second surface of said second adhesive layer has a second profile, further wherein said first profile and said second profile are each independently selected such that,
relative to a comparative multilayered adhesive film comprising said support layer, said first adhesive layer and said second adhesive layer, wherein said comparative multilayered adhesive film is free of said first profile and free of said second profile and has a comparative peel strength between said first surface of said first adhesive layer and said second surface of said second adhesive layer thereof,
said peel strength is less than said comparative peel strength.
[0006] In further accordance with the present invention, there is provided an assembly comprising:
(I) the multilayered adhesive film described above; and
(II) a separate article (e.g., a sheet or wafer, such as, a silicon wafer) having a second surface that is in adhesive contact with the first surface of the second adhesive layer of the multilayered adhesive film.
[0007] As used herein and in the claims, unless otherwise indicated, molecular weights, such as, "number average molecular weights," are determined by gel permeation
chromatography using appropriate standards, such as, polystyrene standards.
[0008] As used herein and in the claims, the term "(meth)acrylate" and similar terms, such as "esters of (meth)acrylic acid" means acrylates and/or methacrylates.
[0009] As used herein, the term "polymer" is meant to refer to both homopolymers, i.e., polymers made from a single monomer species, and copolymers, i.e., polymers made from two or more monomer species.
[0010] As used herein and in the claims, the term "actinic radiation" means
electromagnetic radiation that is capable of initiating free radical polymerization of a composition that includes radically polymerizable ethylenic unsaturation, and includes, but is not limited to, infrared light, visible light, ultraviolet light, electron beam radiation, x- rays, and concurrent and/or sequential combinations thereof.
[0011] The features that characterize the present invention are pointed out with particularity in the claims, which are annexed to and form a part of this disclosure. These and other features of the invention, its operating advantages, and the specific objects obtained by its use will be more fully understood from the following detailed description and accompanying drawings in which preferred embodiments of the invention are illustrated and described.
[0012] As used herein and in the claims, terms of orientation and position, such as, "upper," "lower," "inner," "outer," "right," "left," "vertical," "horizontal," "top," "bottom," and similar terms, are used to describe the invention as oriented in the drawings. Unless otherwise indicated, the use of such terms is not intended to represent a limitation upon the scope of the invention, in that the invention may adopt alternative positions and orientations.
[0013] Unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of " 1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, e.g., 1 to 6.1 , 3.5 to 7.8, 5.5 to 10, etc.
[0014] Unless otherwise indicated, all numbers or expressions, such as those expressing structural dimensions, quantities of ingredients, etc., as used in the specification and claims are understood as modified in all instances by the term "about."
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 is a representative sectional view of a multilayered adhesive film according to the present invention;
[0016] Figure 2 is a representative exploded sectional view of a multilayered adhesive film according to the present invention, in which the first surface of the first adhesive layer thereof has a first profile; [0017] Figure 3 is a representative exploded sectional view of a multilayered adhesive film according to the present invention, in which the second surface of the second adhesive layer thereof has a second profile;
[0018] Figure 4(a) is a representative sectional view of a comparative multilayered adhesive film that is free of first and second profiles at the adhesive interface between the first and second adhesive layers;
[0019] Figure 4(b) is a representative exploded sectional view of the comparative multilayered adhesive film of Figure 4(a);
[0020] Figures 5(a) through 5(h) are representative partial perspective views of microstructures having various shapes from which the first and second profiles may be selected;
[0021 ] Figure 6 is a representative partial perspective view of a profile that includes neighboring elevated points and neighboring points of reduced elevation;
[0022] Figure 7 is a representative sectional view of an assembly according to the present invention that includes the multilayered adhesive film of the present invention and a separate article in adhesive contact with the second adhesive layer thereof;
[0023] Figure 8(a) is a representative sectional view of the assembly of Figure 6, in which a dicing lane has been formed therein;
[0024] Figure 8(b) is a representative sectional view of the assembly of Figure 8(a), in which a portion of a chip having a portion of the second adhesive layer adhered thereto is picked-up and separated from the first adhesive layer; and
[0025] Figure 8(c) is a representative sectional view of the chip of Figure 8(b) that has been adhesively contacted with a separate substrate.
[0026] In Figures 1 through 8(c), like reference numerals designate the same components and structural features, unless otherwise indicated.
DETAILED DESCRIPTION OF THE INVENTION
[0027] With reference to Figures 1 -3 of the drawings, a multilayered adhesive film 1 according to the present invention is depicted. Multilayered adhesive film 1 includes a support layer 1 1 , having a first adhesive layer 14 thereon, and a second adhesive layer 17 on the first adhesive layer. Support layer 1 1 has a first surface 20 and a second surface 21 that are opposed from each other (e.g., face substantially away from each other). First adhesive layer 14 has a first surface 26 and a second surface 23 that are opposed from each other (e.g., face substantially away from each other). Second adhesive layer 17 has a first surface 32 and a second surface 29 that are opposed from each other (e.g., face
substantially away from each other).
100281 In particular, second surface 23 of first adhesive layer 14 is in adhesive contact with first surface 20 of support layer 1 1. As used herein and in the claims, adhesive contact between the second surface of the first adhesive layer and the first surface of the support layer means: (i) direct adhesive contact therebetween; or (ii) indirect adhesive contact therebetween due to a separate layer or film (e.g., a separate adhesive layer or film) being interposed therebetween. In an embodiment, the second surface of the first adhesive layer and the first surface of the support layer are in direct adhesive contact with each other.
100291 First surface 26 of first adhesive layer 14 and second surface 29 of second adhesive layer 17 are in adhesive contact with each other, and have a peel strength therebetween. Typically, the first surface of the first adhesive layer and the second surface of the second adhesive layer are in direct adhesive contact with each other.
[0030] First surface 32 of second adhesive layer 17 defines an exterior adhesive surface 44 (e.g., an exterior upper adhesive surface 44) of multilayered adhesive film 1. Second surface 21 of support layer 1 1 defines an exterior support surface 41 (e.g., an exterior lower support surface 41) of multilayered adhesive film 1.
[0031] With the multilayered films according to the present invention: first surface 26 of first adhesive layer 14 has a first profile 35; and/or second surface 29 of second adhesive layer 17 has a second profile 38. See, for example, Figures 2 and 3. As such, the adhesive interface 47 between the first 14 and second 17 adhesive layers has a profiled interface 50. See, for example, Figure 1.
[00321 The first (e.g., 35) and second (e.g., 38) profiles are each independently selected such that the peel strength between the first (e.g., 14) and second (e.g., 17) adhesive layers, of the multilayered film according to the present invention, is less than the comparative peel strength between the first and second adhesive layers of a comparative multilayered adhesive film that is free of the first profile and free of the second profile. The comparative multilayered film has a support layer, first adhesive layer, and second adhesive layer; each having the same composition as the multilayered film according to the present invention. In addition, the comparative multilayered film is fabricated under substantially the same conditions (e.g., pressure and temperature) as that of the
multilayered film according to the present invention. With the comparative multilayered adhesive film, however, the first surface of the first adhesive layer is free of the first profile; and the second surface of the second adhesive layer is free of the second profile. The comparative multilayered film has a comparative peel strength between the first and second adhesive layers thereof.
[0033] For purposes of illustration, and with reference to Figures 4(a) and 4(b), comparative multilayered adhesive film Γ includes: a first layer 1 1 having a first surface 20 and a second surface 21 that are opposed from each other; a first adhesive layer 14' having a first surface 26' and a second surface 23 that are opposed from each other; and a second adhesive layer 17' having a first surface 32 and a second surface 29' that are opposed from each other. Second surface 23 of first adhesive layer 14' and first surface 20 of support layer 1 1 are in adhesive contact with each other. Second surface 29' of second adhesive layer 17' and first surface 26' of first adhesive layer 14' are in adhesive contact with each other. First surface 26' of first adhesive layer 14' is substantially free of a first profile (e.g., free of first profile 35), and second surface 29' of second adhesive layer 17' is substantially free of a second profile (e.g., free of second profile 38). As such, the adhesive interface 47' between the first 14' and second 17' adhesive layers of comparative multilayered adhesive film 1 ' is substantially free of a profiled interface therebetween (e.g., free of profiled interface 50).
[0034] The support layer 1 1 , first adhesive layer 14', and second adhesive layer 17' of comparative multilayered adhesive film each have substantially the same compositions and dimensions (e.g., thickness) as the support layer 1 1 , first adhesive layer 14, and second adhesive layer 17 of the multilayered adhesive film 1 according to the present invention. [0035] The comparative peel strength between the first and second adhesive layers of a comparative multilayered adhesive film may vary widely, depending, for example, on the compositions of the adhesive layers and whether the first adhesive layer is at least partially cured. Typically, a comparative multilayered adhesive film has a comparative peel strength (or adhesive force) (between the first and second adhesive layers thereof) that is from 1 1.6 Newtons per meter (N/M) to 38.6 N/M (30 grams force per inch (gF/inch) to 100 gF/inch), or from 1 1.6 N/M to 30.9 N/M (30 gF/inch to 80 gF/inch), or from 1 1.6 N/M to 23.2 N/M (30 gF/inch to 60 gF/inch), as determined at room temperature, a 180° peeling value, at a peeling speed of 305 mm / minute (12 inches / minute).
[0036] The multilayered adhesive films according to the present invention typically have a peel strength (between the first and second adhesive layers) that is at least 50 percent less than the comparative peel strength (between the first and second adhesive layers) of a comparative multilayered adhesive film. The multilayered adhesive films according to the present invention may have a peel strength (between the first and second adhesive layers) that is at least 60 percent less than, or at least 70 percent less than the comparative peel strength (between the first and second adhesive layers) of a comparative multilayered adhesive film.
100 71 The reduction in the peel strength between the first and second adhesive layers of the multilayered adhesive films according to the present invention, relative to the peel strength between the first and second adhesive layers of a comparative multilayered adhesive film, is typically less than 100% (i.e., the peel strength typically is not reduced by 100%). The reduction in the peel strength between the first and second adhesive layers of the multilayered adhesive films according to the present invention, relative to the peel strength between the first and second adhesive layers of a comparative multilayered adhesive film, typically has an upper limit of 99%, or 95%, or 90%, or 85%. For example, the peel strength between the first and second adhesive layers of the multilayered adhesive films according to the present invention may be reduced by from 50% to 99%, or from 60% to 95%, or from 60% to 90%, or from 70% to 85%, relative to the peel strength between the first and second adhesive layers of a comparative multilayered adhesive film.
[00381 The peel strength between the first and second adhesive layers of multilayered adhesive films according to the present invention may vary widely, depending, for example, on the compositions of the adhesive layers and whether the first adhesive layer is at least partially cured. Typically, multilayered adhesive films according to the present invention have a peel strength (between the first and second adhesive films thereof) that is from 0.39 N/M to 9.65 N/M (1 gF/inch to 25 gF/inch), or from 0.58 N/M to 7.72 N/M (1.5 gF/inch to 20 gF/inch), or from 0.77 N/M to 5.79 N/M (2 gF/inch to 15 gF/inch), as determined at room temperature, a 180° peeling value, at a peeling speed of 305 mm / minute (12 inches / minute.
[0039] The peel strength between the first adhesive layer and the support layer of the multilayered adhesive films according to the present invention is greater than the peel strength between the first and second adhesive layers, such that when the first and second adhesive layers are separated from each other, the first adhesive layer and the support layer remain substantially adhered to each other. Typically, the peel strength (or adhesive force) between the first adhesive layer and the support layer of the multilayered adhesive films according to the present invention, is from 78 N/M to 390 N/M (200 gF/inch to 1000 gF/inch), or from 195 N/M to 312 N/M (500 gF/inch to 800 gF/inch), as determined at room temperature, a 90° peeling value, at a peeling speed of 305 mm / minute (12 inches / minute). If a separate article (e.g., a silicon wafer) is in adhesive contact with the first surface of the second adhesive layer of the multilayered adhesive films according to the present invention, the peel strength between the separate article and the second adhesive layer is greater than the peel strength between the first and second adhesive layers, such that when the first and second adhesive layers are separated from each other, the separate article and the second adhesive layer remain substantially adhered to each other.
[0040] With the multilayered adhesive film of the present invention: the first surface (e.g., 26) of the first adhesive layer (e.g., 14) has a first profile (e.g., 35); and/or the second surface (e.g., 29) of the second adhesive layer (e.g., 17) has a second profile (e.g., 38). In an embodiment: the first surface (e.g., 26) of the first adhesive layer (e.g., 14) has a first profile (e.g., 35); and the second surface (e.g., 29) of the second adhesive layer (e.g., 17) is free of the second profile (e.g., 38).
[0041] The first profile and the second profile of the multilayered adhesive film of the present invention each independently and typically, include a plurality of microstructures that may have substantially the same shapes or different shapes. In an embodiment, the first profile and the second profile each independently include a plurality of
microstructures independently having a shape selected from conical shapes, pyramidal shapes, ridges, channels, rectangular shapes, spheroidal shapes, oval shapes, conical shapes, irregular shapes, and combinations of two or more thereof.
[0042] For purposes of non-limiting illustration and with reference to Figures 5(a) through 5(h), microstructures of the first profile 35, having various shapes are depicted on first surface 26 of first adhesive layer 14. For purposes of ease of illustration, the various microstructure shapes are depicted in Figures 5(a) through 5(h) as residing substantially on first surface 26 of first adhesive layer 14. Without intending to be bound by any theory, the microstructures are believed in actuality to reside both within and above first surface 26 of first adhesive layer 14, and correspondingly to also define first surface 26. The profile 38 of second surface 29 of second adhesive layer 17 may also or alternatively include the various microstructure shapes depicted in and as described with reference to Figures 5(a) through 5(h).
[004 1 First profile 35 may include microstructures having conical shapes 53, as depicted in Figure 5(a). First profile 35 may include microstructures having pyramidal shapes 56, as depicted in Figure 5(b). As depicted in Figure 5(c), first profile 35 may include microstructures having ridges 59 and/or channels 62. First profile 35 may include microstructures having spheroidal (including hemispheroidal) shapes 65, as depicted in Figure 5(d). As depicted in Figure 5(e), first profile 35 may include microstructures having oval (e.g., elliptical) shapes 68. With reference to Figure 5(f), first profile 35 may include microstructures having rectangular shapes 71 (e.g., recta-tubular shapes, including square tubular shapes). First profile 35 may include microstructures having cylindrical shapes 74, as depicted in Figure 5(g). As depicted in Figure 5(h), first profile 35 may include microstructures having irregular shapes 77. The first and second profiles may each independently include microstructures having two or more of the recited and representatively depicted shapes.
[0044] The microstructures of the first and second profiles, each typically and
independently, have or define a plurality of elevated points. Each elevated point typically has at least one neighboring elevated point, and thus, define a plurality of neighboring pairs of elevated points. The average distance between neighboring pairs of elevated points may be quantified, for example by means of micrographic (e.g., photomicrographic) analysis of the profiled surface. In an embodiment, the first profile and the second profile each independently have a plurality of elevated points, and the first profile and the second profile each independently have an average distance between neighboring pairs of the elevated points that is typically greater than or equal to 10 μιη and less than or equal to 300 μιη, for example, greater than or equal to 25 μηι and less than or equal to 250 μιη.
[0045] For purposes of non-limiting illustration, and with reference to Figure 6, first profile 35 of first surface 26 of first adhesive layer 14 is depicted as including
microstructures having conical shapes 53, each having or defining an elevated point 80. A neighboring pair of elevated points 83 has a distance 86 therebetween. Comparing a plurality of distances 86 between a plurality of neighboring pairs of elevated points 83 provides an average distance between neighboring pairs of the elevated points.
[0046] In addition to having or defining a plurality of elevated points, the
microstructures of the first and second profiles, each typically and independently, have or define a plurality of points or reduced elevation (that are vertically lower relative to the plurality of elevated points). Each point of reduced elevation typically has at least one neighboring point or reduced elevation, and thus, define a plurality of neighboring pairs of points of reduced elevation. The average distance between neighboring pairs of points of reduced elevation may be quantified, for example, by means of micrographic (e.g., photomicrographic) analysis of the profiled surface. In an embodiment, the first profile and the second profile each independently have a plurality of points of reduced elevation, and the first profile and the second profile each independently have an average distance between neighboring pairs of the points of reduced elevation that is typically greater than or equal to 10 μηι and less than or equal to 300 μιη, for example, greater than or equal to 25 μηι and less than or equal to 250 μιη.
[0047] For purposes of non-limiting illustration, and with further reference to Figure 6, first profile 35 of first surface 26 of first adhesive layer 14 is depicted as including microstructures having conical shapes 53, each having or defining a point of reduced elevation 89. A neighboring pair of points of reduced elevation 92 has a distance 95 therebetween. Comparing a plurality of distances 95 between a plurality of neighboring pairs of points of reduced elevation 92 provides an average distance between neighboring pairs of the points of reduced elevation.
[0048] The first and second profiles may each be independently formed by methods including, for example, chemical etching, surface cutting (or engraving), and/or compressive imprinting (e.g., stamping).
[0049] With an actinic radiation curable adhesive layer, such as, the first adhesive layer, chemical etching may be used to profile the surface. For example, a mask is typically positioned on or over the surface to be profiled, and actinic radiation (e.g., ultraviolet light) is applied through the mask, but only so as to result in polymerization to a limited depth below the surface (the limited depth being less than the total thickness of the adhesive layer). The mask is removed, and the surface is developed by exposure to a suitable solvent that removes a non-cross-linked polymer from certain (e.g., unexposed) surface regions, thus, resulting in a profiled adhesive surface. Surface cutting may be achieved by impinging a high-pressure liquid jet (e.g., water jet, optionally including abrasive media), or a beam of high energy electromagnetic radiation (e.g., a high energy laser) onto the adhesive surface, so as to remove portions of the adhesive polymer material (e.g., by localized abrasion and/or localized pyrolization).
[0050] In an embodiment, the first and second profiles are each independently formed by compressive imprinting (e.g., stamping or embossing) of the adhesive surface. With compressive imprinting, a template having a negative representation or form of the desired profile on a surface thereof, is pressed against and/or into the adhesive surface under conditions of elevated pressure and optionally elevated temperature. By negative representation or form with regard to the template means that depressions on the template surface form elevated points on the profiled adhesive surface, and elevated points on the template surface form depressions within the profiled adhesive surface. The template may be fabricated from any suitable material, provided it is harder than the adhesive surface against / into which it is compressed. For example, the template may be fabricated from, one or more metals, ceramics (e.g., glass), and/or cross-linked polymers. The template may be substantially solid, or it may be in the form of a mesh or screen.
[0051] In an embodiment, the template used to form the first profile and/or the second profile is a screen or mesh fabricated from metal. In a further embodiment, the template is a metal screen or mesh from a particulate sieve, having a screen mesh size (or designation) that is greater than or equal to 10 μηι and less than or equal to 300 μηι, for example, greater than or equal to 25 μιη and less than or equal to 250 μιπ (e.g., selected from 25 μηι mesh, 55 μιη mesh, and/or 250 μηι mesh screens).
[0052] The support layer of the multilayered adhesive film of the present invention may be fabricated from any suitable material, such as paper, metal (e.g., metal foil), polymeric materials, ceramics (e.g., glass, such as glass sheet or woven fiber glass mat), and combinations (including blends and/or multiple layers) thereof. The support layer may include a single layer or multiple layers (e.g., 2 or more layers). Multilayered support layers may be fabricated by art-recognized methods, such as, coextrusion and/or lamination. Adjacent layers of the multilayered support layer may abut each other directly or have an adhesive (or tie) layer interposed therebetween. Each layer of the support layer, that includes one or more polymeric materials, may independently be subjected to uniaxial stretching (or drawing), biaxial stretching, or be free of uniaxial and biaxial stretching. In an embodiment, the support layer is composed of a single layer.
10053 J The first surface (e.g., first surface 20) of the support layer may be subjected to art-recognized surface treatments for purposes including, but not limited to, improving adhesion to the first adhesive layer (e.g., 14). Examples of surface treatments to which the first surface of the support layer may be subjected include, but are not limited to, exposure acids, such as, chromic acid, exposure to ozone, flame treatment, exposure to one or more ionized gasses, and combinations thereof. In addition, or alternatively, the first surface (e.g., 20) of the support layer may be defined by a coating, such as a silane functional coating. Coatings may be applied to the support layer by art-recognized methods, such as, spraying, dipping, and curtain coating. The second surface (e.g., 21) of the support layer may be subjected to the same treatments (e.g., adhesion promoting treatments, including coatings) as the first surface thereof. Typically, the second surface of the support layer is not subjected to adhesion promoting treatments.
[00541 In an embodiment, the support layer includes at least one layer that includes a polymer, which may be selected from thermoplastic polymers, thermoset polymers, and combinations thereof. Examples of polymers from which the support layer may be fabricated, but are not limited to, polyolefms such as low density polyethylene, linear polyethylene, linear low density polyethylene, middle density polyethylene, high density polyethylene, super low density polyethylene, random and block copolymerized
polyolefins, such as, copolymers having monomer residues selected from two or more of ethylene, propylene, butene, pentene and hexene, ethylene/vinyl acetate copolymer, ionomer resins, ethylene/(meth)acrylic acid copolymer, ethylene/(meth)acrylic acid ester (random or alternate) copolymer, polyurethanes, polyesters such as, polyethylene terephthalate, and polyethylene naphthalate, polycarbonates, polyimides, polyamides, polyetheretherketones, polyphenylsulfide,; fluorine-containing polymers, polyvinyl chloride, polyvinylidene chloride, cellulose resins, silicone resins, and combinations thereof.
[0055] In an embodiment, the support layer is composed of a single layer, includes a polyolefin, such as polyethylene, and has a melting point of from 60°C to 120°C (e.g., about 70°C).
[0056] Each layer of the support layer may independently include one or more additives. Examples of additives that may be independently included in each layer (e.g., each polymeric layer) of the support layer include, but are not limited to, thermal stabilizers, ultraviolet light stabilizers, pigments, dyes, antistatic agents, plastisizers, and
combinations thereof.
[00571 In an embodiment, and as will be discussed in further detail herein, the first adhesive layer (e.g., 14) is at least partially curable by exposure to actinic radiation (e.g., ultraviolet light, X-rays, and/or electron beam). When the first adhesive layer is at least curable by exposure to actinic radiation, the support layer (e.g., 1 1) in an embodiment is substantially transparent to actinic radiation (i.e., it has a high transmission of actinic radiation therethrough). As such, actinic radiation impinged upon the second surface (e.g., 21) of the support layer (e.g., 1 1) passes through the body or core of the support layer, out through the first surface (e.g., 20) of the support layer, and into the first adhesive layer (e.g., 14), so as to result in at least partial curing (e.g., photo-polymerization) of the first adhesive layer.
[0058] The support layer may have any suitable thickness, provided it is capable of supporting and withstanding operations that the upper layers may be subjected to (e.g., chip dicing operations, as will be discussed further herein). The support layer typically has a thickness of from 5 μηι to 200 μηι, or from 10 μηι to 150 μηι, or from 20 μηι to 100 μιη.
[0059] The first adhesive layer may include a single layer or multiple layers (e.g., 2 or more layers). When the first adhesive layer includes two or more layers, each layer may have the same or different compositions. Typically, the first adhesive layer is composed of a single layer.
[0060] The first adhesive layer is formed on the first surface of the support layer, by art- recognized methods. For example, the first adhesive layer may be laminated or extruded onto the first surface of the support layer. The combination of the support layer and the first adhesive layer, which may be referred to as a tape, may be stored for a period of time, after which the second adhesive layer is applied to the first adhesive layer. A release film may be applied to the first surface of the first adhesive layer, and the combination of the support layer, the first adhesive layer, and the release film are rolled up. The release film prevents fusion between the first surface of the first adhesive layer and the second surface of the support layer when the combination is formed into a roll. The release film is removed before the second adhesive layer is formed on the first adhesive layer.
[0061] The first adhesive layer typically includes a self-adhesive material, such as a pressure sensitive adhesive material, and may be a thermoplastic first adhesive layer or a curable first adhesive layer (e.g., curable by exposure to elevated temperature and/or actinic radiation). The first adhesive layer may include polymers selected from, but not limited to, rubbers (including synthetic and/or natural rubbers), acrylic polymers, silicone polymers, polyvinyl ethers, and combinations of two or more thereof.
[0062] Acrylic polymers that may be included in the first adhesive layer, typically include residues of esters of (meth)acrylic acid, such as Ci-C20-(meth)acrylate monomers, including linear or branched C3-C2o-(meth)acrylate monomers, cyclic C3~C2o- (meth)acrylate monomers, and aromatic C5-C i4-(meth)acrylate monomers. Typically, the esters of (meth)acrylic acid are selected from Ci-C2o-alkyl(meth)acrylates. Examples of Ci-C20-alkyl (meth)acrylates include, but are not limited to, methyl (mefh)acrylate, ethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxypropyl (mefh)acrylate, isopropyl (mefh)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate and 3,3,5-trimethylcyclohexyl (meth)acrylate. Examples of cycloalkyl (meth)acrylates include, but are not limited to,
cyclopropyl(meth)acrylate, cyclobutyl(meth)acrylate, cyclopentyl(meth)acrylate, cyclohexyl(meth)acrylate, cycloheptyl(meth)acrylate, and isobornyl(meth)acrylate.
[0063] For purposes of modifying (e.g., increasing) the adhesiveness of the first adhesive layer, the esters of (meth)acrylic acid may optionally be copolymerized with one or more monomers having active hydrogen groups, such as, carboxylic acid groups, phosphoric acid groups, sulfonic acid groups, thiol groups, and/or hydroxyl groups. Copolymerizable monomers having active hydrogen groups are typically present in amounts of less than or equal to 40 percent by weight, based on total weight of monomers. Examples of copolymerizable monomers containing carboxylic acid groups (or which may be converted to contain carboxylic acid groups) include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and acid anhydride monomers such as, maleic anhydride, and itaconic anhydride. A non-limiting example of
copolymerizable monomer containing a phosphoric acid group is 2-hydroxyethylacryloyl phosphate. Examples of copolymerizable monomers that include a sulfonic acid group include, but are not limited to, styrenesulfonic acid, allylsulfonic acid, 2- (meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of copolymerizable monomers containing hydroxyl groups include, but are not limited to, 2- hydroxyethyl(meth)acrylate, 2-hydiOxypropyl(mefh)acrylate, 4-hydroxybutyl
(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 8-hydroxyoctyl(meth)acrylate, 10- hydroxydecyl(meth)acrylate, 12-hydroxylauryl(meth)acrylate, and (4- hydroxylmethylcyclohexyl)methyl(meth)acrylate.
[0064] The esters of (meth)acrylic acid may further optionally be copolymerized with polyfunctional monomers, for purposes of increasing the crosslink density of the resulting acrylic polymer. Examples of the polyfunctional monomers include, but are not limited to, hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol
di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. If present, such polyfuncational monomers are present in amounts of less than or equal to 10 percent by weight, for example less than or equal to 5 percent by weight, abased on total monomer weight.
[0065] The molecular weight of the acrylic polymer of the first adhesive layer may vary widely, and is generally selected such that the first adhesive layer has desirable adhesive qualities. Typically, the number average molecular weight of the acrylic polymer is at least 200,000 and less than or equal to 4,000,000 (e.g., from 300,000 to 3,500,000, or from 400,000 to 3,000,000).
[0066] The first adhesive layer may be a curable first adhesive layer, that is curable (i.e., cross-linkable) by exposure to elevated temperature and/or actinic radiation. Curing the curable first adhesive layer may be desirable for reasons including, but not limited to, reducing the adhesive properties of the first adhesive layer. Thermal curing of the first adhesive layer may be achieved by including one or more cross-linking agents that become reactive (e.g., by loss of a blocking or capping group) with active hydrogen functionality (e.g., hydroxyl, thiol, primary amine, secondary amine, and/or carboxylic acid groups) of the polymer. Examples of art-recognized cross-linking agents include, but are not limited to, polyisocyanates, polyoxiranes (i.e., polyepoxides), and melamines. Cross-linking agents are typically used in amounts of less than 10 percent by weight, such as, from 0.1 to 5 percent by weight, based on the total weight of polymer and cross-linking agent.
[0067] The first adhesive layer may alternatively be curable by exposure to actinic radiation (e.g., ultraviolet light, electron beam, and/or X-rays). The actinic radiation curable first adhesive layer may include: a high molecular weight polymer that is free of ethylenic unsaturation (e.g., an acrylic polymer as described previously herein); an ethylenically unsaturated oligomer, and/or ethylenically unsaturated monomer; and an actinic radiation activated initiator (e.g., a photoinitiator). Alternatively, the actinic radiation curable first adhesive layer may include: a polymer (e.g., an acrylic polymer) having pendent and/or terminal ethylenic unsaturation; optionally, an ethylenically unsaturated oligomer and/or ethylenically unsaturated monomer; and an actinic radiation activated initiator (e.g., a photoinitiator).
[0068] Pendent and/or terminal ethylenic unsaturation may be introduced into an acrylic polymer by art-recognized methods. For example, an acrylic polymer having pendent and/or terminal active hydrogen groups (e.g., hydroxyl, thiol, primary amine, secondary amine, or carboxylic acid groups) may be subsequently reacted with (meth)acrylic monomers that are reactive with such active hydrogen groups, such as oxirane functional (meth)acrylates (e.g., glycidol (meth)acrylate) and isocyanate functional (meth)acrylates (e.g., methacryloyl isocyanate).
[0069] The ethylenically unsaturated oligomer and ethylenically unsaturated monomer components may each independently have at least one (e.g., two or more) ethylenically unsaturated groups. Examples of ethylenically unsaturated monomer components include, but are not limited to, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol
tetrakis(meth)acrylate, dipentaerythritolmonohydroxy pentakis(meth)acrylate,
dipentaerythritol hexakis(meth)acrylate, and 1 ,4-butanediol di(meth)acrylate. Examples of ethylenically unsaturated oligomers include, but are not limited to, those terminated with (meth)acrylate groups, and having backbones selected from urethane, polyether, polyester, polycarbonate, and/or polybutadiene. Ethylenically unsaturated oligomers may have molecular weights from 100 to 30,000.
[0070] Photoinitiators that may be used in the actinic radiation curable first adhesive layer include those known to the skilled artisan. Examples of photoinitiators include, but are not limited to: a-ketol compounds, such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2- propyl)ketone, a-hydroxy-a, a'-dimethylacetophenone, 2-methyl-2- hydroxypropiophenone, and 1 -hydroxy cyclohexyl phenyl ketone; acetophenone
compounds, such as methoxyacetophenone, 2,2-dimethoxy-2-plienylacetophenone, 2,2- diethoxyacetophenone, and 2-methyl-l -[4-(methylthio)-phenyl]-2-morpholinopropane-l ; benzoin ether compounds, such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; ketal compounds, such as benzyl dimethyl ketal; aromatic sulfonyl chloride compounds, such as 2-naphthalenesulfonyl chloride; optically active oxime compounds, such as l -phenone-l , l-propanedione-2-(o-ethoxycarbonyl)oxime;
benzophenone compounds, such as benzophenone, benzoylbenzoic acid, and 3,3'- dimethyl-4-methoxybenzophenone; thioxanthone compounds, such as thioxanthone, 2- chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone,
isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4- diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphonoxides; acylphosphonates; and combinations of two or more thereof.
[0071] The amount of photoinitiator(s) present is typically selected so as to result in a combination of: a desired level of cure (e.g., as measured by increased surface hardness); within a limited amount of time; and with exposure to a certain level of actinic radiation for a given amount of time. Typically, the photoinitiator is present in an amount of less than or equal to 20 percent by weight (e.g., from 0.05 to 20 percent by weight, based on total weight of resin components).
[00721 Each layer of the first adhesive layer may independently include one or more additives. Examples of additives that may be independently included in each layer (e.g., each polymeric layer) of the first adhesive layer include, but are not limited to, thermal stabilizers, ultraviolet light stabilizers (e.g., with first adhesive layers that are not photopolymerizable), pigments, dyes, antistatic agents, plastisizers, and combinations thereof.
[0073] The first adhesive layer may have any suitable thickness (e.g., such that it may retain a profile imparted upon the first surface thereof). Typically, the first adhesive layer has a thickness that is less than or equal to 100 μηι, such as, from 1 to 50 μπι, or 2 to 30 μηι, or 5 to 25 μηι.
[0074] The second adhesive layer may include a single layer or multiple layers (e.g., 2 or more layers). When the second adhesive layer includes two or more layers, each layer may have the same or different compositions. Typically, the second adhesive layer is composed of a single layer.
[0075] The second adhesive layer may be formed onto at least a portion of the first adhesive layer by art-recognized methods. For example, the second adhesive layer may be laminated or extruded onto at least a portion of the first surface of the first adhesive layer. Typically, the second adhesive layer is laminated onto at least a portion of the first surface of the first adhesive layer.
[0076] Prior to bringing the first surface of the first adhesive layer and the second surface of the second adhesive layer into adhesive contact with each other: the first profile is imparted onto (or into) the first surface of the first adhesive layer; and/or the second profile is imparted onto (or into) the second surface of the second adhesive layer. The methods by which the first and second profiles are each independently imparted onto the respective adhesive surface include, but are not limited to, those discussed previously herein.
[0077] Imparting the second profile onto/into the second surface of the second adhesive film may be conducted while the second adhesive layer is retained on a transfer film (or carrier film). For example, while the first surface of the second adhesive layer is in separable (or reversible) adhesive contact with a transfer film, the second profile is imparted/formed onto/into the second surface of the transfer film supported second adhesive layer. The profiled second adhesive layer may be separated from the transfer film and then adhesively contacted with the first surface of the first adhesive layer.
Alternatively, the profiled second adhesive layer may be adhesively contacted with the first surface of the first adhesive layer, while the transfer film is in separable (or reversible) adhesive contact with the first surface of the second adhesive layer. After adhesively contacting the first and second adhesive layers together, the transfer film may be retained in contact with the first surface of the second adhesive layer until it is desired to bring the first surface of the second adhesive layer into adhesive contact with a separate article, such as, a silicon wafer.
[0078] Similarly, if a second profile is not imparted on the second surface of the second adhesive layer, the second adhesive layer may be adhesively contacted with the first surface (having a first profile) of the first adhesive layer, while a transfer film is in separable (or reversible) adhesive contact with the first surface of the second adhesive layer. The transfer film may be optionally retained in contact with the first surface of the second adhesive layer until, for example, a separate article, such as, a silicon wafer, is brought into adhesive contact with the first surface of the second adhesive layer.
[0079] The composition of the second adhesive layer is typically selected such that, with a separate article (e.g., a silicon wafer) retained in adhesive contact with the first surface thereof, the second surface thereof is capable of subsequently adhering to a separate substrate (e.g., a semiconductor device) after separation from the first adhesive layer. The second adhesive layer typically includes a thermoplastic polymer and/or a thermoset polymer. In an embodiment, the composition of the second adhesive layer is selected such that the first surface thereof may be adhesively contacted with a separate article (e.g., a silicon wafer) at a temperature of less than or equal to 70°C (e.g., at room temperature, or about 25°C).
[0080] Classes of thermoplastic polymers that may be included in the second adhesive layer include, but are not limited to: saturated polyesters; polyurethanes; polyamides (e.g., nylon polymers); polyimides; silicone polymers; elastomeric polymers, such as rubber polymers, including natural and/or synthetic rubber polymers, such as functionally terminated butadiene acrylonitrile rubbers, including, for example, epoxy-terminated butadiene acrylonitrile rubbers (ETBN's), amino-terminated butadiene acrylonitrile rubbers (ATBN's), carboxy-terminated butadiene acrylonitrile rubbers (CTBN's), and hydroxy-terminated butadiene acrylonitrile rubbers (HTBN's); poly(meth)acrylates; and combinations of two or more thereof. Classes of thermoset polymers that may be included in the second adhesive layer include, but are not limited to, thermoset epoxy polymers, thermoset unsaturated polyesters, thermoset acrylic polymers, and thermoset phenol resins.
[0081] In an embodiment, the second adhesive layer includes a non-elastomeric polymer and an elastomeric polymer. The non-elastomeric polymer may be selected from art- recognized non-elastomeric polymers, including those classes and examples of
thermoplastic polymers as previously recited, such as: saturated polyesters; polyurethanes; polyamides (e.g., nylon polymers); polyimides; silicone polymers; poly(meth)acrylates; polyethers, including polyepoxides; and combinations of two or more thereof. The elastomeric polymer may be selected from art-recognized elastomeric polymers, including, rubber polymers, including natural and/or synthetic rubber polymers, such as, functionally terminated butadiene acrylonitrile rubbers, including, for example, epoxy-terminated butadiene acrylonitrile rubbers (ETBN's), amino-terminated butadiene acrylonitrile rubbers (ATBN's), carboxy-terminated butadiene acrylonitrile rubbers (CTBN's), and hydroxy-terminated butadiene acrylonitrile rubbers (HTBN's); and combinations of two or more thereof.
[0082] In an embodiment, the non-elastomeric polymer is selected from
poly(meth)acrylates and/or polyethers, such as polyepoxides; and the elastomeric polymer is selected from one or more functionally terminated butadiene acrylonitrile rubbers, such as, epoxy-terminated butadiene acrylonitrile rubbers (ETBN's), amino-terminated butadiene acrylonitrile rubbers (ATBN's), carboxy-terminated butadiene acrylonitrile rubbers (CTBN's), and/or hydroxy-terminated butadiene acrylonitrile rubbers (HTBN's).
[0083] The non-elastomeric polymer may be present in the second adhesive layer in an amount of from 5 to 95 percent by weight, or from 10 to 75 percent by weight, or from 25 to 55 percent by weight, based in each case on the total weight of non-elastomeric polymer and elastomeric polymer. The elastomeric polymer may be present in the second adhesive layer in an amount of from 5 to 95 percent by weight, or from 25 to 90 percent by weight, or from 45 to 75 percent by weight, based in each case on the total weight of non- elastomeric polymer and elastomeric polymer.
[0084] Each layer of the second adhesive layer may independently include one or more additives. Examples of additives that may be independently included in each layer (e.g., each polymeric layer) of the second adhesive layer include, but are not limited to, thermal stabilizers, ultraviolet light stabilizers, pigments, dyes, antistatic agents, plastisizers, and combinations thereof.
[0085] The second adhesive layer may have any suitable thickness. For example, the second adhesive layer may have a thickness of from 5 μιη to 100 μηι, or from 10 μηι to 50 μηι.
[0086] The present invention also relates to an assembly that includes the multilayered adhesive film of the present invention, as described above, and a separate article (e.g., a sheet or wafer, such as a semiconductor wafer) having a second surface that is in adhesive contact with the first surface of the second adhesive layer. As used herein and in the claims, adhesive contact between the second surface of the separate article and the first surface of the second adhesive layer means: (i) direct adhesive contact therebetween; or (ii) indirect adhesive contact therebetween due to a separate layer or film (e.g., a separate adhesive layer or film) being interposed therebetween. In an embodiment, the second surface of the separate article and the first surface of the second adhesive layer are in direct adhesive contact with each other.
[0087] For purposes of non-limiting illustration, and with reference to Figure 7 of the drawings, assembly 3 includes a multilayered adhesive film 1 according to the present invention and a separate article 98 that is in adhesive contact with second adhesive layer 17 of multilayered adhesive film 1. Separate article 98 has a first surface 101 and a second surface 104 that are substantially opposed from each other (e.g., face substantially away from each other). Second surface 104 of separate article 98 and first surface 32 of second adhesive layer 17 are in adhesive contact with each other.
[0088] The separate article may have any suitable shape, such as three-dimensional shapes or substantially flat shapes, such as in the form of a sheet or film. Typically, the separate article is in the form of a sheet or film, and may be substantially continuous or discontinuous (e.g., in the form of a mesh or screen). Generally, the separate article is in the form of a substantially continuous sheet or film.
[0089] The separate article may be fabricated from any suitable material, such as, thermoplastic polymers, thermoset polymers, metals, ceramics, semiconductor materials (e.g., semiconductor wafers comprising silicon), or any combination thereof. In an embodiment, the separate article is a silicon wafer (e.g., a semiconductor wafer
comprising silicon). The silicon wafer may include other materials, such as, germanium, gallium arsenide, and/or silicon carbide.
[0090] The separate article may have a wide range of thicknesses. In an embodiment, when the separate article is a silicon wafer, it may have a thickness of from 5 to 1000 micrometers (μηι), or from 25 to 300 μηι.
[0091] The assembly of the present invention may be formed by art-recognized methods. Typically, the multilayered adhesive film is separately formed (or pre-formed), and the separate article and the second adhesive layer of the multilayered adhesive film are brought into adhesive contact with each other under conditions of elevated pressure and optionally elevated temperature. For example, when the separate article is a silicon wafer, the silicon wafer and the second adhesive layer of the multilayered adhesive film are brought into adhesive contact with each other under an applied pressure of from 0.0125 to 1.45 pounds per square inch (psi) (86 to 9997 pascal), and a temperature of from 20 to 120°C.
[0092] With the assembly of the present invention so formed, the first surface of the separate article (e.g., a silicon wafer) may be subjected to processing steps, including, for example, planarizing, polishing (e.g., chemical mechanical polishing), and/or scoring. After completion of any processing steps (e.g., polishing) with regard to the first surface of the separate article, the first adhesive layer of the multilayered adhesive film is optionally subjected to a curing step. For example, when the first adhesive layer is photocurable, the second surface of the support layer may be exposed to an actinic radiation source (e.g., a UV light source). The actinic radiation passes through the support layer and into to first adhesive layer, thus resulting in curing of the first adhesive layer. With the first adhesive layer so cured, the adhesive force between the first adhesive layer and the second adhesive layer is generally reduced.
[0093] When the separate article is a wafer, such as, a silicon wafer, the assembly is typically subjected to a dicing step, after processing of the first surface of the wafer.
Dicing typically involves cutting the silicon wafer into a plurality of separate chip preforms that are still adhered to the support layer of the multilayered film (or dicing-die attach film). The silicon wafer is subjected to an appropriate cutting method, such as, by means of, a laser or a fluid jet cutter (e.g., a water jet) that may optionally include an abrasive media. Dicing of the silicon wafer results in the formation of a plurality of intersecting dicing lanes, which typically extend down through the second adhesive layer, the first adhesive layer, and optionally partially into the support layer (but not all of the way through the support layer). Dicing also results in the formation of a plurality of separate chip preforms.
[0094] With reference to Figure 8(a), assembly 3 of Figure 7 has been subjected to a dicing step, and includes separate chip preforms 107 having a dicing lane 1 10
therebetween. Dicing lane 1 10 extends down to first surface 20 of support layer 1 1 of multilayered adhesive film 1 , which in Figures 8(a) and 8(b) is a dicing die attach film. While dicing lane 1 10 may optionally extend partially into support layer 1 1 , it does not extend all of the way through support layer 1 1.
[0095] After completion of the dicing step, the chip preforms are subjected to a pick-up step. A pick-up tool removes a chip, that includes a diced wafer with a diced portion of the second adhesive layer attached thereunder, from the first adhesive layer. The chip is then moved to and adhesively contacted to a separate substrate (e.g., a semiconductor element) by means of the second adhesive layer residing under the diced wafer. The second adhesive layer may then be crosslinked and cured, for example by exposure to elevated temperature, thereby fixedly attaching the chip to the semiconductor element.
[0096] For purposes of non-limiting illustration and with reference to Figures 8(b) and 8(c), chip 1 13, which includes diced wafer 98 and a diced portion of second adhesive layer 17 adhered thereunder, is lifted up and separated from first adhesive layer 14 by a pick-up tool (not shown). First adhesive layer 14 remains adhered to support layer 1 1. The pickup tool generally includes an elongated arm having a terminal head that contacts first surface 101 of wafer 98 with reduced pressure (e.g., suction) therebetween. The elongated arm of the pick-up tool may be attached to a linear actuator (not shown) that vertically repositions the head of the pick-up tool relative to the diced assembly 3(a). During the pick-up step, the diced assembly 3(a) is usually retained, e.g., within a frame (not shown).
[0097] The pick-up tool next moves chip 1 13 to a separate substrate 1 16 (e.g., a semiconductor element), and brings the second surface 29 of the second adhesive layer 17 into adhesive contact with the first surface 1 19 of the separate substrate 1 16. With chip 1 13 so adhered to separate substrate 1 16, second adhesive layer 17 may optionally be subjected to a curing step. For example, the combination of chip 1 13 adhered to separate substrate 1 16 may be subjected to elevated temperature, resulting in cross-linking and cure of second adhesive layer 17, thereby, fixedly attaching chip 1 13 to separate substrate 1 16. The separate substrate may be, for example, a semiconductor element, such as, a lead frame, and may include a plurality of chips 1 13 adhered thereto. In addition, or
alternatively, chip 1 13 may be adhered to one or more underlying chips 1 13 (not shown) that are together adhered to separate substrate 1 16.
[0098] As discussed previously herein, the peel strength (or adhesive force) between the separate article and the second adhesive layer is greater than the peel strength between the first and second adhesive layers, such that when the first and second adhesive layers are separated from each other, the separate article and the second adhesive layer remain substantially adhered to each other. In an embodiment, when the separate article is a wafer, such as a silicon wafer, the peel strength (or adhesive force) between the separate article and the second adhesive layer of the multilayered adhesive films according to the present invention is from 78 N/M to 390 N/M (200 gF/inch to 1000 gF/inch), or from 195 N/M to 312 N/M (500 gF/inch to 800 gF/inch), as determined at room temperature, a 180° peeling value, at a peeling speed of 305 mm / minute (12 inches / minute).
[0099] In an embodiment of the assembly of the present invention, the first and second profiles are each independently and additionally selected such that, increasing a distance between the separate article and the support layer, results in separation of the first surface of the first adhesive layer and the second surface of the second adhesive layer from each other. Concurrently with such separation, adhesive contact is maintained between the second surface of the first adhesive layer and the first surface of the support layer, and adhesive contact is maintained between the separate article and the first surface of the second adhesive layer.
[0100] For purposes of non-limiting illustration and with reference to Figure 8(b), diced wafer portion 98 and support 11 of chip preform 107 have a first distance 122
therebetween. As the distance between diced wafer portion 98 and support 11 is increased, such as, to second distance 125 (e.g., by means of a pick-up tool, not shown) first surface 26 of first adhesive layer 14 and second surface 29 of second adhesive layer 17 (of chip 113) are separated from each other. As illustrated in Figure 8(b), second distance 125 is greater than first distance 122. While the first and second adhesive layers are separated from each other: adhesive contact is maintained between second surface 23 of first adhesive layer 14 and first surface 20 of support layer 11 ; and adhesive contact is maintained between second surface 104 of separate article (e.g., wafer) 98 and first surface 32 of second adhesive layer 17.
[0101] The multilayered films of the present invention may be used in a number of applications. Typically, the multilayered films of the present invention are used in conjunction with processes where it is desirable to retain an article or ware in place during initial processing steps, and then selectively separate the ware from the multilayered film so as to allow processed portions of the ware to be adhered (by means of a retained portion of the multilayered film) to a separate substrate in one or more subsequent processing steps. In an embodiment, the multilayered film of the present invention is a dicing die attach film, which may be used in the processing of wafers, such as, silicon wafers / chips. Correspondingly, in an embodiment of the assembly of the present invention, the multilayered film of the assembly is a dicing die attach film, and the separate article thereof is a wafer, such as, a semiconductor wafer (e.g., a silicon wafer).
[0102] The present invention is more particularly described in the following examples, which are intended to be illustrative only, since numerous modifications and variations therein will be apparent to those skilled in the art. Unless otherwise specified, all parts and percentages are by weight.
EXAMPLES
[0103] Multilayered adhesive films according to the present invention were prepared in accordance with the following description. A dicing tape was obtained commercially from Denki Kagaku Kogyo Kabushiki Kaisha, under the tradename ERX-8005 dicing tape. The dicing tape had a polyolefin support layer having a melting point of about 70°C, and a pressure sensitive adhesive layer thereover, composed of an ultraviolet light curable acrylic polymer. Polyester wire mesh screens having dimensions of 20 cm x 20 cm were cut from sieves having mesh size designations of 25 μιη, 55 μιη, and 250 μηι. The sieves were obtained commercially from Filter Specialists Inc. of Indiana, USA .
[0104] The pressure sensitive adhesive layers of the dicing tape samples were embossed with each of the wire mesh screens at a temperature of 65°C and a pressure of 2 psi. After embossing, the wire mesh screens were separated from the pressure sensitive adhesive layer. Comparative (or control) samples of the dicing tape were not embossed with wire mesh screens.
[0105] Multilayered adhesive films according to the present invention were formed by laminating EASY STACK ATB-130U adhesive film (a rubberized epoxy containing film, obtained commercially from Henkel Corporation) over the pressure sensitive adhesive layer of the embossed dicing tapes, at a temperature of about 25°C and a pressure of 0.29 psi (2000 pascal). Comparative (or control) multilayered adhesive films were prepared by laminating EASY STACK ATB-130U adhesive film over the pressure sensitive adhesive layers of the dicing tape samples that had not been embossed, at a temperature of about 25°C and a pressure of 0.29 psi (2000 pascal). [0106] The multilayered adhesive films according to the present invention, and the comparative multilayered adhesive films were subjected to UV light, so as to cure the pressure sensitive adhesive layers thereof. The inventive and comparative multilayered adhesive films were exposed to 400 mJ/cm2 of UV light using a Model 18672 ultraviolet light exposure system (commercially available from UVEXS Incorporated) fitted with a 385 nm UV lamp.
[0107] Multilayered adhesive films according to the present invention, and comparative multilayered adhesive films each having dimensions of 2.5 cm x 20 cm were evaluated for peel strength between the EASY STACK ATB- 130U layer and the UV cured pressure sensitive adhesive layer in accordance with the following description. Three test samples each were evaluated using a TA.XTPlus Analyzer obtained commercially from Stable Micro Systems, Ltd, at room temperature and at a peeling speed of 305 mm / minute (12 inches / minute) to obtain 180° peel strength values. The peel strength results are summarized in the following Table- 1.
Table- 1
Figure imgf000030_0001
The peel strength values are provided as: average value ± standard deviation. The peel strength values represent the steady-state peel strength of the samples.
(2) Average percent reduction in average peel strength relative to the comparative
multilayered adhesive film.
(3) NA means Not Applicable.
[0108] The results summarized in Table- 1 show that multilayered adhesive films according to the present invention (e.g., Examples A, B, and C) have a peel strength between the first and second adhesive layers thereof that is less than the comparative peel strength between the first and second adhesive layers of a comparative multilayered adhesive film (that is free of a profile, e.g., a first profile, therebetween). In addition, the results summarized in Table- 1 show that the reduction in peel strength can be controlled by selection of the profile imparted at the interface between the first and second adhesive layers, and in particular, as demonstrated to the first surface of the first adhesive layer of the multilayered adhesive films according to the present invention.
[0109] The present invention has been described with reference to specific details of particular embodiments thereof. It is not intended that such details be regarded as limitations upon the scope of the invention except insofar as and to the extent that they are included in the accompanying claims.

Claims

WHAT IS CLAIMED IS:
1. A multilayered adhesive film comprising:
(a) a support layer having a first surface;
(b) a first adhesive layer having a first surface and a second surface that are opposed from each other, said second surface of said first adhesive layer and said first surface of said support layer being in adhesive contact with each other; and
(c) a second adhesive layer having a first surface and a second surface that are opposed from each other, said first surface of said first adhesive layer and said second surface of said second adhesive layer being in adhesive contact with each other and having a peel strength therebetween,
wherein, at least one of,
(i) said first surface of said first adhesive layer has a first profile, and
(ii) said second surface of said second adhesive layer has a second profile, further wherein said first profile and said second profile are each independently selected such that,
relative to a comparative multilayered adhesive film comprising said support layer, said first adhesive layer and said second adhesive layer, wherein said comparative multilayered adhesive film is free of said first profile and free of said second profile and has a comparative peel strength between said first surface of said first adhesive layer and said second surface of said second adhesive layer thereof,
said peel strength is less than said comparative peel strength.
2. The multilayered adhesive film of Claim 1, wherein said first profile and said second profile each independently comprise a plurality of microstructures independently having a shape selected from conical shapes, pyramidal shapes, ridges, channels, rectangular shapes, spheroidal shapes, oval shapes, conical shapes, irregular shapes, and combinations of two or more thereof.
3. The multilayered adhesive film of Claim 1, wherein said first profile and said second profile each independently comprise a plurality of elevated points, said first profile and said second profile each independently having an average distance between neighboring pairs of said elevated points of greater than or equal to 10 μηι and less than or equal to 300 μηι.
4. The multilayered adhesive film of Claim 1 , wherein said first surface of said first adhesive layer has said first profile, and said second surface of said second adhesive layer is substantially free of said second profile.
5. The multilayered adhesive film of Claim 1, wherein said peel strength is at least 50 percent less than said comparative peel strength.
6. The multilayered adhesive film of Claim 1 , wherein said peel strength is at least 60 percent less than said comparative peel strength.
7. The multilayered adhesive film of Claim 1 , wherein said peel strength is at least 70 percent less than said comparative peel strength.
8. The multilayered adhesive film of Claim 1 , wherein said peel strength is from 1 gf/inch to 25 gf/inch.
9. The multilayered adhesive film of Claim 1 , wherein said support layer comprises a polyolefin resin.
10. The multilayered adhesive film of Claim 1 , wherein said first adhesive film is curable.
1 1. The multilayered adhesive film of Claim 10, wherein said first adhesive film is at least partially cured by exposure to actinic radiation.
12. The multilayered adhesive film of Claim 11, wherein said support layer is substantially transparent to actinic radiation.
13. The multilayered adhesive film of Claim 1, wherein said second adhesive film comprises a non-elastomeric resin and an elastomeric resin.
14. The multilayered adhesive film of Claim 1, wherein said multilayered adhesive film is a dicing die attach film.
15. An assembly comprising:
(I) a multilayered adhesive film comprising,
(a) a support layer having a first surface,
(b) a first adhesive layer having a first surface and a second surface that are opposed from each other, said second surface of said first adhesive layer and said first surface of said support layer being in adhesive contact with each other, and
(c) a second adhesive layer having a first surface and a second surface that are opposed from each other, said first surface of said first adhesive layer and said second surface of said second adhesive layer being in adhesive contact with each other and having a peel strength therebetween,
wherein, at least one of,
(i) said first surface of said first adhesive layer has a first profile, and
(ii) said second surface of said second adhesive layer has a second profile, further wherein said first profile and said second profile are each independently selected such that,
relative to a comparative multilayered adhesive film comprising said support layer, said first adhesive layer and said second adhesive layer, wherein said comparative multilayered adhesive film is free of said first profile and free of said second profile and has a comparative peel strength between said first surface of said first adhesive layer and said second surface of said second adhesive layer thereof,
said peel strength is less than said comparative peel strength; and
(II) a separate article having a second surface in adhesive contact with said first surface of said second adhesive layer.
16. The assembly of Claim 15, wherein said first profile and said second profile each independently comprise a plurality of microstructures independently having a shape selected from conical shapes, pyramidal shapes, ridges, channels, rectangular shapes, spheroidal shapes, oval shapes, irregular shapes, and combinations of two or more thereof.
17. The assembly of Claim 15, wherein said first profile and said second profile each independently comprise a plurality of elevated points, said first profile and said second profile each independently having an average distance between neighboring pairs of said elevated points of greater than or equal to 10 μηι and less than or equal to 300 μιη.
18. The assembly of Claim 15, wherein said first profile and said second profile are each independently and additionally selected such that,
increasing a distance between said separate article and said support layer, results in separation of said first surface of said first adhesive layer and said second surface of said second adhesive layer from each other, while adhesive contact is maintained between said second surface of said first adhesive layer and said first surface of said support layer, and while adhesive contact is maintained between said separate article and said first surface of said second adhesive layer.
19. The assembly of Claim 15, wherein said peel strength is at least 50 percent less than said comparative peel strength.
20. The assembly of Claim 15, wherein said multilayered adhesive film is a dicing die attach film, and said separate article is a silicon wafer.
PCT/US2011/064789 2011-02-22 2011-12-14 Multilayered adhesive film WO2012115701A2 (en)

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