CN117321744A - Conductive sheet and dicing die bonding film - Google Patents

Conductive sheet and dicing die bonding film Download PDF

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Publication number
CN117321744A
CN117321744A CN202280035889.XA CN202280035889A CN117321744A CN 117321744 A CN117321744 A CN 117321744A CN 202280035889 A CN202280035889 A CN 202280035889A CN 117321744 A CN117321744 A CN 117321744A
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CN
China
Prior art keywords
conductive sheet
particles
mass
conductive
resin
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CN202280035889.XA
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Chinese (zh)
Inventor
三田亮太
市川智昭
大木场祐一
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Nitto Denko Corp
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Nitto Denko Corp
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Publication of CN117321744A publication Critical patent/CN117321744A/en
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    • 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
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • 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
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • 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
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • 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
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
    • H01L21/52—Mounting semiconductor bodies in containers

Abstract

The conductive sheet of the present invention contains a binder resin and conductive particles, and has a viscosity of 10 to 10000kPa s at 70 ℃ and an elongation at break of 110% or more at 70 ℃.

Description

Conductive sheet and dicing die bonding film
Cross-reference to related applications
The present application claims priority from japanese patent application No. 2021-100176, which is incorporated by reference into the description of the present application.
Technical Field
The present invention relates to a conductive sheet and a dicing die bonding film.
Background
Conventionally, as a method (die bonding method) of bonding a semiconductor element (semiconductor chip) to an adherend such as a metal lead frame in the manufacture of a semiconductor device, a method using a conductive sheet has been known (for example, patent document 1 below).
Patent document 1 below discloses a sheet containing conductive particles and a thermosetting resin as the conductive sheet.
Patent document 1 discloses the following: after a semiconductor element (semiconductor chip) is mounted on one surface of the conductive sheet, the other surface of the conductive sheet is brought into contact with an adherend such as a metal lead frame, and then the conductive sheet is thermally cured at a specific temperature (for example, 200 ℃) to be bonded to the adherend such as a metal lead frame.
However, in recent years, high density integration of semiconductor devices is increasingly demanded.
In order to realize high density integration of a semiconductor device, it is necessary to thin the thickness of a semiconductor element (semiconductor chip).
Further, since the semiconductor element (semiconductor chip) is obtained by dicing a semiconductor wafer by dicing with a blade or the like, the thickness of the semiconductor wafer needs to be reduced in order to reduce the thickness of the semiconductor element (semiconductor chip).
However, as the thickness of the semiconductor chip is made thinner, warpage of the semiconductor wafer is more likely to occur.
As described above, if the semiconductor wafer is warped, there is a problem that the dicing of the semiconductor wafer by the dicing of the blade or the like cannot be performed with high accuracy.
In order to solve such warpage problem, a semiconductor wafer (for example, a TAIKO (registered trademark) wafer) manufactured by mechanically polishing so that an inner portion from an outer periphery to several 10mm remains in a ring shape is known (for example, patent document 2 below).
Since the semiconductor wafer has the annular portion as described above, even if the portion on the inner side of the annular portion is polished to be thin, warpage of the semiconductor wafer can be suppressed.
The TAIKO (registered trademark) wafer has a step portion formed between the annular portion and a portion on the inner side of the annular portion, and the maximum height of the step portion is usually about 450 μm, and the thickness of the flat plate portion obtained by mechanical polishing is usually about 20 μm.
Prior art literature
Patent literature
Patent document 1: japanese patent application laid-open No. 2019-21813
Patent document 2: japanese patent laid-open publication No. 2013-12690
Disclosure of Invention
Problems to be solved by the invention
However, as described above, a semiconductor wafer such as a TAIKO (registered trademark) wafer is formed with a step portion between the annular portion and a portion further inside than the annular portion.
That is, such a semiconductor wafer is a semiconductor wafer having a height difference portion.
Therefore, when a semiconductor element (semiconductor chip) is obtained, there are cases where: if the conductive sheet is mounted on the semiconductor wafer having the height difference portion as described above, the conductive sheet cannot sufficiently follow the height difference portion.
In such a case, a relatively large void (a void formed from the edge of the step to the inside of the edge more than 500 μm) may be generated between the semiconductor wafer having the step and the conductive sheet from the edge of the step toward the center of the semiconductor wafer having the step.
As described above, if a relatively large gap is generated between the semiconductor wafer having the height difference portion and the conductive sheet, the conductive sheet is easily peeled from the semiconductor wafer having the height difference portion at the time of dicing or the like with the gap as a starting point.
In addition, when a gap is generated between the semiconductor element (semiconductor chip) and the conductive sheet after dicing, the semiconductor element (semiconductor chip) with the conductive sheet cannot exhibit sufficient characteristics.
Therefore, if a relatively large gap is generated between the semiconductor wafer having the height difference portion and the conductive sheet, there is a problem in that: the ratio of the semiconductor element (semiconductor chip) with the conductive sheet obtained after dicing as a component of the semiconductor device can be reduced, that is, the yield is reduced.
However, it is difficult to say that a sufficient study has been performed on a conductive sheet capable of sufficiently following the step portion when mounted to a semiconductor wafer having the step portion.
Accordingly, an object of the present invention is to provide a conductive sheet capable of sufficiently following a step portion when mounted on a semiconductor wafer having the step portion, and a dicing die bonding film including the conductive sheet.
Solution for solving the problem
The conductive sheet of the present invention contains a binder resin and conductive particles,
the conductive sheet has a viscosity of 10 to 10000kPa s at 70 ℃,
the elongation at break at 70 ℃ is 110% or more.
In the above-mentioned conductive sheet material, the conductive layer,
the content of the conductive particles is preferably 85% by mass or more and 97% by mass or less.
In the above-mentioned conductive sheet material, the conductive layer,
preferably, the conductive particles include at least 1 selected from the group consisting of silver particles, copper particles, silver oxide particles, and copper oxide particles.
In the above-mentioned conductive sheet material, the conductive layer,
preferably, the binder resin comprises a thermosetting resin.
In the above-mentioned conductive sheet material, the conductive layer,
preferably, the composition further comprises a volatile component having a volatilization initiation temperature of 100 ℃ or higher.
The dicing die bonding film of the present invention comprises:
dicing tape having adhesive layer laminated on base layer, and method for manufacturing dicing tape
A conductive sheet laminated on the adhesive layer of the dicing tape,
the conductive sheet is any one of the conductive sheets described above.
Drawings
Fig. 1 is a cross-sectional view showing a structure of a dicing die bonding film according to an embodiment of the present invention.
Fig. 2A is a schematic cross-sectional view illustrating a case of a wafer mounting process.
Fig. 2B is a schematic cross-sectional view illustrating a case of dicing die-bonding film arrangement process.
Fig. 2C is a schematic cross-sectional view illustrating a case of the sealing process.
Fig. 2D is a schematic cross-sectional view illustrating a case of the depressurizing step.
Fig. 2E is a schematic cross-sectional view illustrating a case of cutting the die bonding film contact process.
Fig. 2F is a schematic cross-sectional view illustrating a case of the dicing die-bonding film bonding process.
Detailed Description
An embodiment of the present invention will be described below.
[ conductive sheet ]
The conductive sheet of the present embodiment contains a binder resin and conductive particles.
In the present specification, the conductive particles refer to particles having an electrical conductivity of 100. Mu.S/cm or less as measured in accordance with JIS K0130 (2008).
The conductive sheet of the present embodiment has a viscosity of 10kPa s to 10000kPa s at 70 ℃.
Further, the conductive sheet of the present embodiment has an elongation at break at 70 ℃ of 110% or more.
Hereinafter, a reference symbol η may be given to the viscosity at 70 ℃ and a reference symbol Bpe may be given to the elongation at break at 70 ℃.
The conductive sheet can have a sufficient sheet shape by setting the viscosity at 70 ℃ to 10kPa s or more, and can have a proper hardness by setting the viscosity at 70 ℃ to 10000kPa s or less.
Further, by setting the elongation at break at 70 ℃ to 110% or more, the conductive sheet can be made to have excellent toughness, that is, the conductive sheet can be made to be ductile and to have excellent strength.
By having the above characteristics, the conductive sheet according to the present embodiment can sufficiently follow the height difference portion when mounted on a semiconductor wafer having the height difference portion.
In the present specification, the term "sufficiently follow the height difference portion" means that a void generated from an edge of the height difference portion toward a center of a semiconductor wafer having the height difference portion is 500 μm or less.
When the viscosity at 70 ℃ is less than 10kpa·s, the conductive sheet becomes a paste-like conductive composition, which cannot maintain the sheet shape.
Since such a paste-like conductive composition is rich in deformability, the paste-like conductive composition can sufficiently follow the level difference portion of the semiconductor wafer having the level difference portion, but it becomes difficult to mount the paste-like conductive composition to the semiconductor wafer having the level difference portion with a uniform thickness.
In addition, if the conductive sheet is a paste-like conductive composition, it is difficult to transfer the conductive sheet to a semiconductor wafer having a step portion in a state where a dicing die bonding film is produced.
Further, after the conductive sheet is mounted on the semiconductor wafer having the level difference portion, the semiconductor wafer is cut into a flat semiconductor wafer inside the level difference portion, and then the flat semiconductor wafer is diced to be cut into a plurality of semiconductor chips.
Then, the semiconductor chip is mounted on an adherend such as a metal lead frame, and is used as a component of a semiconductor device.
However, in the case where the conductive sheet is formed into a paste-like conductive composition as described above, dicing cannot be performed with high accuracy, and the paste-like conductive composition overflows from the end edge of the semiconductor chip in a state where the semiconductor chip is formed and mounted on a metal lead frame or the like.
If the paste-like conductive composition overflows in this way, a short circuit is caused when the paste-like conductive composition is used as a member of a semiconductor device, which is not preferable.
The binder resin includes thermoplastic resins, thermosetting resins, and the like.
The conductive sheet of the present embodiment preferably contains a thermosetting resin.
The inclusion of the thermosetting resin can thermally cure the conductive sheet, and thus can improve adhesion to an adherend (for example, a metal lead frame).
The conductive sheet of the present embodiment more preferably contains a thermoplastic resin in addition to the thermosetting resin.
By including a thermoplastic resin in addition to the thermosetting resin, the conductive sheet can be made to have relatively low elasticity even after the conductive sheet is thermally cured.
Further, by including the thermoplastic resin, the viscosity η of the conductive sheet at 70 ℃ can be adjusted to be not less than 10kpa·s and not more than 10000kpa·s relatively easily.
Examples of the thermosetting resin include epoxy resin, phenolic resin, amino resin, unsaturated polyester resin, polyurethane resin, silicone resin, and thermosetting polyimide resin. Among them, epoxy resins are preferably used.
Examples of the epoxy resin include bisphenol a type, bisphenol F type, bisphenol S type, brominated bisphenol a type, hydrogenated bisphenol a type, bisphenol AF type, biphenyl type, naphthalene type, fluorene type, phenol novolac type, cresol novolac type, o-cresol novolac type, triphenylmethane type, tetrahydroxyphenylethane, hydantoin type, triglycidyl isocyanurate type, and glycidylamine type epoxy resins. Among them, at least one of bisphenol a type epoxy resin and cresol novolac type epoxy resin is preferably used, and bisphenol a type epoxy resin and cresol novolac type epoxy resin are more preferably used in combination.
Examples of the bisphenol a epoxy resin include aliphatic modified bisphenol a epoxy resins.
Examples of the phenolic resin as the curing agent for the epoxy resin include polyhydroxystyrene such as novolac type phenolic resin, resol type phenolic resin, biphenyl type phenolic resin, and poly-p-hydroxystyrene. Among the phenolic resins, biphenyl type phenolic resins are preferably used.
In addition, as the thermosetting resin, a thermoplastic resin having a thermosetting functional group may be used. Examples of the thermoplastic resin having a thermosetting functional group include an acrylic resin having a thermosetting functional group. The acrylic resin of the thermosetting functional group-containing acrylic resins includes an acrylic resin containing a monomer unit derived from a (meth) acrylate.
For the thermoplastic resin having a thermosetting functional group, the curing agent may be selected according to the kind of the thermosetting functional group.
Examples of the thermoplastic resin include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resin such as polyamide 6 or polyamide 6, saturated polyester resin such as phenoxy resin, acrylic resin, PET or PBT, polyamide imide resin, and fluororesin. The thermoplastic resin may be used alone or in combination of two or more. The thermoplastic resin is preferably an acrylic resin from the viewpoint of having less ionic impurities and high heat resistance, and easily securing connection reliability by the conductive sheet.
The acrylic resin is preferably a polymer containing a monomer unit derived from a (meth) acrylic acid ester as the most monomer unit in mass ratio. Examples of the (meth) acrylic acid ester include alkyl (meth) acrylate, cycloalkyl (meth) acrylate, and aryl (meth) acrylate. The acrylic resin may contain a monomer unit derived from another component copolymerizable with the (meth) acrylic acid ester. Examples of the other component include carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, functional group-containing monomers such as acrylamide and acrylonitrile, and various polyfunctional monomers.
The acrylic resin is preferably a carboxyl group-containing acrylic polymer.
In the conductive sheet of the present embodiment, the mass% of the binder resin in 100 mass% (parts by mass) of the conductive sheet is preferably 1.5 mass% or more and 40 mass% or less, more preferably 4 mass% or less and 25 mass% or less.
When the conductive sheet according to the present embodiment contains the thermosetting resin and the thermoplastic resin as the binder resin, the mass% of the thermosetting resin is preferably 1 mass% or more and 30 mass% or less, more preferably 2 mass% or more and 18 mass% or less, of 100 mass% of the conductive sheet.
In addition, the mass% of the thermoplastic resin in 100 mass% of the conductive sheet is preferably 0.5 mass% or more and 10 mass% or less, more preferably 1 mass% or more and 7 mass% or less.
Further, when the binder resin is composed of the thermosetting resin and the thermoplastic resin, the mass ratio of the thermosetting resin is preferably 30 to 90 mass%, more preferably 40 to 70 mass%, based on 100 mass% of the binder resin.
Examples of the conductive particles include particles such as silver particles, silver oxide particles, nickel particles, copper oxide particles, aluminum particles, carbon black, and carbon nanotubes, particles obtained by plating the surface of metal particles as cores (cores) with a metal such as gold or silver (hereinafter also referred to as "plated particles"), and particles obtained by metal-coating the surface of resin particles as cores (cores) (hereinafter also referred to as "metal-coated resin particles"). These conductive particles may be used alone or in combination of two or more.
The conductive sheet of the present embodiment preferably contains at least 1 kind selected from the group consisting of silver particles, copper particles, silver oxide particles, and copper oxide particles in the conductive particles as described above.
By including the particles as described above as the conductive particles, the conductive sheet may exhibit sufficient electrical conductivity and thermal conductivity.
Examples of the shape of the particles such as silver particles, silver oxide particles, nickel particles, copper oxide particles, aluminum particles, carbon black, and carbon nanotubes include flaky, needle-like, filament-like, spherical, and flat (including scaly) particles, and among them, spherical particles are preferable.
By using spherical particles, dispersibility of the particles in the conductive sheet can be improved.
In addition, the conductive sheet of the present embodiment particularly preferably contains silver particles in these particles.
The silver particles may be silver particles composed of a silver element and other elements (metal elements and the like) contained as unavoidable impurity elements, or may be silver particles subjected to a surface treatment (for example, a silane coupling treatment). Examples of the surface treatment agent for silver particles include fatty acid-based, amine-based, and epoxy-based coating agents.
In the following, silver particles surface-treated with a coating agent such as a fatty acid-based coating agent, an amine-based coating agent, or an epoxy-based coating agent may be referred to as coating agent-treated silver particles.
In the conductive sheet of the present embodiment, silver particles are preferably treated with a coating agent as the silver particles. By treating silver particles with a coating agent as the silver particles, affinity with a binder resin (thermosetting resin, thermoplastic resin, or the like) contained in the conductive sheet can be improved, and the silver particles can be easily dispersed in the conductive sheet.
As the metal-plated particles, for example, particles having nickel particles or copper particles as cores and having surfaces of the cores plated with noble metals such as gold or silver can be used.
As the metal-coated resin particles, for example, particles in which the surface of the core is coated with a metal such as nickel or gold using the resin particles as the core can be used.
As the shape of the metal-coated particles or the metal-coated resin particles, for example, flake-like, needle-like, filament-like, spherical, flat (including scale-like) particles can be used, and among them, spherical particles are preferable.
As the shape of the metal-plated particles or the metal-coated resin particles, the dispersibility of the metal-plated particles or the metal-coated resin particles in the conductive sheet can be improved by using spherical particles.
When the conductive sheet of the present embodiment contains metal-plated particles, particles in which copper particles are used as cores and the surfaces of the cores are plated with silver (silver-coated copper particles) are preferably used as the metal-plated particles.
Examples of the silver-coated copper particles include particles having a silver layer of 10 mass% applied to flat copper particles, and particles having a silver layer of 20 mass% applied to spherical copper particles.
In the conductive sheet of the present embodiment, the mass% of the conductive particles (i.e., the content ratio of the conductive particles) in 100 mass% (parts by mass) of the conductive sheet is preferably 60 mass% or more and 98 mass% or less, more preferably 80 mass% or more and 97 mass% or less, and still more preferably 85 mass% or more and 97 mass% or less.
The conductive sheet of the present embodiment preferably contains silver particles and silver-coated copper particles as the conductive particles.
In this case, the silver particles preferably account for 10 parts by mass or more and 95 parts by mass or less, more preferably 20 parts by mass or more and 90 parts by mass or less, of 100 parts by mass of the conductive particles.
The viscosity η at 70℃is preferably 50kPa s or more, more preferably 70kPa s or more, and still more preferably 100kPa s or more.
The viscosity η at 70℃is preferably 7000kPa·s or less, more preferably 5000kPa·s or less, and even more preferably 3500kPa·s or less.
By setting the viscosity η at 70 ℃ within the above-described numerical range, the sheet shape of the conductive sheet can be more sufficiently maintained, and the conductive sheet can be made to have more appropriate hardness.
The viscosity η at 70 ℃ can be evaluated using a rheometer (Thermo Fisher Scientific inc. Manufactured by rotary rheometer HAAKE MARS).
Specifically, the strain amount was 0.1% at a Gap value of 250. Mu.m, a frequency of 1Hz, and a value indicating 70℃was read when the temperature was increased from 30℃to 180℃at a temperature increase rate of 10℃per minute.
The elongation at break Bpe at 70 ℃ is preferably 112% or more, more preferably 113% or more, and even more preferably 114% or more.
By setting the elongation at break Bpe at 70 ℃ within the above-described numerical range, the toughness of the conductive sheet can be further improved.
That is, the conductive sheet can be made more ductile and the strength of the conductive sheet can be made more excellent.
The upper limit of the elongation at break Bpe at 70℃is usually 200%.
Elongation at break Bpe at 70℃can be evaluated using a tensile tester (for example, model "AGS-X" manufactured by Shimadzu corporation).
Specifically, the evaluation can be performed as follows.
(1) A conductive sheet having a width of 10mm, a length of 30mm and a thickness of 200 μm was prepared.
(2) Polyimide tapes were attached to both longitudinal end sides of the conductive sheet to obtain a sample. Specifically, in the above-mentioned conductive sheet, a polyimide tape was attached to a region extending from the upper edge in the longitudinal direction to a distance of 10mm from the upper edge in the longitudinal direction, and a polyimide tape was attached to a region extending from the lower edge in the longitudinal direction to a distance of 10mm from the lower edge in the longitudinal direction, so that a sample was obtained.
(3) The upper end side of the sample in the longitudinal direction is mounted on one chuck of the tensile testing machine, and the lower end side of the sample in the longitudinal direction is mounted on the other chuck of the tensile testing machine.
(4) After the tensile tester equipped with the sample was placed in a constant temperature bath, the temperature in the constant temperature bath was raised to 70 ℃.
(5) After 3 minutes from the temperature in the constant temperature bath reaching 70 ℃, the sample was stretched in the longitudinal direction at a distance of 10mm between chucks and a stretching speed of 50 mm/min, and the data obtained in the stretching test were plotted on a graph having a horizontal axis of travel (in mm) and a vertical axis of test force (tensile strength; in N).
(6) In the graph, the time at which the test force reached the maximum was regarded as the time at which the conductive sheet broke, and the stroke value at which the test force reached the maximum was read, divided by the effective length of the conductive sheet (10 mm; length of the non-attached polyimide tape portion), and multiplied by 100, to thereby calculate the elongation at break at 70 ℃.
The conductive sheet of the present embodiment can be obtained by: the content ratio of the binder resin and the content ratio of the conductive particles in the conductive sheet are appropriately adjusted to appropriately adjust the viscosity η at 70 ℃ and the elongation at break Bpe at 70 ℃.
For example, the viscosity η at 70 ℃ may be adjusted to a higher value by increasing the content of the conductive particles in the conductive sheet or to a lower value by decreasing the content of the conductive particles.
The elongation at break at 70 ℃ can be adjusted to a higher value by decreasing the content of the conductive particles in the conductive sheet, or to a lower value by increasing the content of the conductive particles.
Further, when the conductive sheet of the present embodiment contains a thermosetting resin and a thermoplastic resin as the matrix resin, the conductive sheet can be obtained by appropriately adjusting the content ratio of the thermosetting resin and the content ratio of the thermoplastic resin to appropriately adjust the viscosity η at 70 ℃ and the elongation at break Bpe at 70 ℃.
The conductive sheet of the present embodiment preferably further contains a volatile component having a volatilization initiation temperature of 100 ℃ or higher.
The volatile component is more preferably a component that volatilizes at 200 ℃ or higher, and still more preferably a component that volatilizes at 250 ℃ or higher.
Examples of such volatile components include organic compounds having 1 or more hydroxyl groups and a volatilization initiation temperature of 100 ℃. The boiling point of the organic compound is preferably 200℃or higher, more preferably 250℃or higher. The boiling point of the organic compound is preferably 350 ℃ or lower. As such an organic compound, terpene compounds are exemplified. Among the terpene compounds, isobornyl cyclohexanol represented by the following formula (1) is preferable as a volatile component. The isobornyl cyclohexanol is an organic compound having a boiling point of 308 to 318 ℃, and has the following properties: when the temperature was raised from room temperature (23.+ -. 2 ℃ C.) to 600 ℃ under a nitrogen gas flow of 200 mL/min at a temperature rise condition of 10 ℃ C./min, the mass was greatly reduced (volatilization started) from 100 ℃ or higher, and the volatilization was ended at 245 ℃ C. (no further mass reduction was observed), and the following properties were also exhibited: exhibits extremely high viscosities of up to 1000000 mPas at 25℃but relatively low viscosities of 1000 mPas or less at 60 ℃. The mass reduction is a value obtained when the mass reduction rate at the measurement start temperature (room temperature) is set to 0%.
In this case, isobornyl cyclohexanol exhibits extremely high viscosity at 25℃as described above, and thus can maintain a sheet shape at room temperature, but exhibits tackiness at 60℃because it exhibits relatively low viscosity as described above. That is, the conductive sheet containing isobornyl cyclohexanol has excellent shape maintaining property at room temperature and has viscosity at 60 ℃ or higher.
Therefore, when a semiconductor element attached to one surface of a conductive sheet is mounted on a metal lead frame or the like, the semiconductor element is generally temporarily adhered (temporarily fixed) to an adherend such as a metal lead frame or the like via the conductive sheet at a temperature of 60 to 80 ℃, but since isobornyl cyclohexanol has an adhesive property at 60 ℃ or more as described above, when the conductive sheet of the present embodiment contains isobornyl cyclohexanol as a volatile component, the temporary adhesion of the conductive sheet to the adherend such as a metal lead frame is further improved. That is, in the state of temporary bonding, the occurrence of a shift in the mounting position of the semiconductor element or the floating of the conductive sheet from the adherend can be suppressed.
In addition, when the conductive sheet contains a thermosetting resin, and the conductive sheet is thermally cured to adhere the semiconductor element to the adherend, adhesion can be performed with high reliability.
The conductive sheet of the present embodiment preferably contains 10 parts by mass or more of the volatile component per 100 parts by mass of the binder resin.
The conductive sheet according to the present embodiment preferably contains 200 parts by mass or less of the volatile component, more preferably 150 parts by mass or less of the volatile component, and still more preferably 100 parts by mass or less of the volatile component, based on 100 parts by mass of the binder resin.
In addition, if the volatile component volatilized at 200 ℃ or higher is contained, the volume of the conductive sheet can be reduced by heating the conductive sheet at 200 ℃ or higher to volatilize the volatile component.
As described above, when the volume of the conductive sheet is reduced, the conductive particles are brought into close positional relationship with each other in the conductive sheet according to the degree of volume reduction, and therefore, it is easy to form a heat conduction path by the conductive particles.
This can relatively improve the thermal conductivity of the conductive sheet.
Further, in the case where the conductive sheet of the present embodiment contains silver particles and silver-coated copper particles as described above, it is considered that when spherical particles are used as the silver-coated copper particles, the specific surface area of the spherical particles is smaller than that of flat particles, and therefore, the contact area between the silver-coated copper particles and the silver particles is smaller than that in the case where spherical particles are used as the silver particles and flat particles are used as the silver-coated copper particles, which is disadvantageous from the viewpoints of electrical conductivity and thermal conductivity.
However, in the case where the conductive sheet of the present embodiment contains a volatile component having a volatilization initiation temperature of 100 ℃ or higher as described above, the volatile component can be volatilized relatively sufficiently when the conductive sheet is heated at a temperature of 150 to 200 ℃ and thermally cured or the like.
In this way, the volume of the conductive sheet can be relatively sufficiently reduced, in other words, the volume of the conductive sheet can be relatively sufficiently contracted, and therefore, the silver-coated copper particles and the silver particles can be brought into close positional relationship.
Therefore, even when spherical particles are used as the silver-coated copper particles, the contact area between the silver-coated copper particles and the silver particles can be sufficiently ensured, and thus, the electrical conductivity and the thermal conductivity can be sufficiently ensured.
When the conductive sheet of the present embodiment contains a thermosetting resin, the conductive sheet of the present embodiment may contain a thermosetting catalyst from the viewpoint of sufficiently allowing the curing reaction of the thermosetting resin to proceed or improving the curing reaction rate. Examples of the heat curing catalyst include imidazole-based compounds, triphenylphosphine-based compounds, amine-based compounds, and trihaloborane-based compounds.
The thickness of the conductive sheet according to the present embodiment is preferably 5 μm or more, more preferably 10 μm or more, and still more preferably 20 μm or more. The thickness of the conductive sheet is preferably 150 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less.
By setting the thickness of the conductive sheet to 150 μm or less, the thermal conductivity can be further improved.
The thickness of the conductive sheet can be obtained by measuring the thickness at any 5 points selected at random using a digital dial gauge (model R-205, manufactured by PEACOCK corporation) and arithmetically averaging these thicknesses, for example.
When the conductive sheet of the present embodiment contains a thermosetting resin, the thermal conductivity after heat curing is preferably 1W/m·k or more, more preferably 3W/m·k or more, and still more preferably 10W/m·k or more.
By setting the thermal conductivity after heat curing to the above numerical range, the electrical conductivity of the conductive sheet can be further improved.
In the conductive sheet of the present embodiment, the upper limit value of the thermal conductivity after heat curing is 420W/m·k at the maximum.
In the conductive sheet of the present embodiment, the upper limit value of the thermal conductivity after heat curing may be 200W/m·k.
The thermal conductivity after thermal curing can be calculated as follows: the conductive sheet according to the present embodiment was heat-cured by treating it at 200 ℃ for 1 hour while applying a pressure of 0.5MPa to the sheet by means of an autoclave apparatus, and the heat-cured conductive sheet was calculated by the following formula.
Thermal conductivity (W/m·k) =thermal diffusivity (m 2 Specific heat (J/g. DEG C.) times specific gravity (g/cm) 3 )
Thermal diffusivity (m) 2 S) can be obtained by TWA method (temperature wave thermal analysis method, measuring apparatus: ai-Phase Mobile, manufactured by ai-Phase Co., ltd.).
The specific heat (J/g. DEG.C.) in the above formula can be measured by DSC method. Specific heat was measured using DSC6220 manufactured by SII Nanotechnology under conditions of a temperature rising rate of 10 ℃/min and a temperature range of 20 to 300 ℃, and based on the obtained data, specific heat was calculated by a method described in JIS manual (specific heat capacity measuring method K-7123).
Further, the specific gravity in the above formula can be measured by the archimedes method.
The conductive sheet according to the present embodiment may contain 1 or 2 or more other components as necessary. Examples of the other component include a filler dispersant, a flame retardant, a silane coupling agent, and an ion scavenger.
At least one surface of the conductive sheet according to the present embodiment is an adhesive surface to be adhered to an adherend.
In other words, the conductive sheet according to the present embodiment can be used for adhesion to an adherend having at least a part of its surface as an adhesion region to be adhered to the conductive sheet.
Even when the adhesion region has irregularities, the conductive sheet according to the present embodiment exhibits good followability to the irregularities.
The conductive sheet according to the present embodiment can remarkably exhibit this effect by providing, on one surface side, an adhesive surface to which both the circular concave portion and the annular convex portion of the semiconductor wafer provided with the circular concave portion and the annular convex portion surrounding the circular concave portion are adhered.
Since the annular convex portion of the semiconductor wafer is formed in a state of protruding from the surface of the circular concave portion, the step portion is formed at the boundary between the annular convex portion and the circular concave portion, but the conductive sheet according to the present embodiment exhibits good followability to the position where the step portion is formed.
The conductive sheet according to the present embodiment may have an adhesive surface having a size capable of covering the entire circular concave portion, or may have an adhesive surface capable of covering the entire circular concave portion and further covering a part or all of the annular convex portion.
The height of the height difference portion may be 5 μm or more and 500 μm or less.
[ dicing die-bonding film ]
Next, the dicing die-bonding film 20 will be described with reference to fig. 1. In the following description, the portions overlapping the conductive sheet will not be described repeatedly.
As shown in fig. 1, the dicing die-bonding film 20 of the present embodiment includes: a dicing tape 10 having an adhesive layer 2 laminated on a base layer 1, and a conductive sheet 3 laminated on the adhesive layer 2 of the dicing tape 10.
In the dicing die bonding film 20, a semiconductor element is attached to the conductive sheet 3. The semiconductor element may be a bare wafer.
The die attached to the dicing die bonding film 20 of the present embodiment is diced into a plurality of die by dicing with a blade, DBG (dicing before polishing, dicing Before Grinding), SDBG (stealth dicing before polishing, stealth Dicing Before Grinding), or the like. In addition, when dicing is performed as described above, the conductive sheet 3 is also diced together with the bare wafer. The conductive sheet 3 is cut into a size corresponding to the size of the singulated bare chips. Thus, a plurality of bare chips with the conductive sheet 3 can be obtained.
The conductive sheet 3 of the dicing die-bonding film 20 contains the binder resin and the conductive particles as described above.
The conductive sheet 3 of the dicing die-bonding film 20 has a viscosity of 10kpa·s to 10000kpa·s at 70 ℃ as described above.
Further, the conductive sheet 3 of the dicing die-bonding film 20 has an elongation at break at 70 ℃ of 110% or more as described above.
The base material layer 1 supports the adhesive layer 2 and the conductive sheet 3 laminated on the adhesive layer 2. The base material layer 1 contains a resin. Examples of the resin include olefin resins such as Polyethylene (PE), polypropylene (PP) and ethylene-propylene copolymers; copolymers containing ethylene as a monomer component such as ethylene-vinyl acetate copolymers (EVA), ionomer resins, ethylene- (meth) acrylic acid copolymers, and ethylene- (meth) acrylic acid ester (random, alternating) copolymers; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); an acrylic resin; polyvinyl chloride (PVC); polyurethane; a polycarbonate; polyphenylene Sulfide (PPS); amide resins such as polyamide and wholly aromatic polyamide (aromatic polyamide); polyetheretherketone (PEEK); polyimide; a polyetherimide; polyvinylidene chloride; ABS (acrylonitrile-butadiene-styrene copolymer); a cellulose resin; a silicone resin; fluororesin, and the like.
From the viewpoint of improving stretchability, the base material layer 1 preferably contains at least 1 selected from the group consisting of polypropylene (PP), polyvinyl chloride (PVC), and ethylene-vinyl acetate copolymer (EVA) as the above resin.
The base material layer 1 may be a laminate in which a 1 st resin layer containing an ethylene-vinyl acetate copolymer (EVA) is used as a central layer, and a 2 nd resin layer containing polypropylene (PP) and a 3 rd resin layer containing polyvinyl chloride (PVC) are laminated on both surfaces of the 1 st resin layer.
The base material layer 1 may contain 1 kind of the above resin, or may contain 2 or more kinds of the above resins.
Examples of the material of the base material layer 1 include polymers (for example, plastic films) such as crosslinked resins described above. The plastic film may be used in an unstretched state, or may be subjected to a uniaxial or biaxial stretching treatment as needed. By using a resin sheet to which thermal shrinkage is imparted by stretching treatment or the like, the adhesive area between the adhesive layer 2 and the conductive sheet 3 can be reduced by thermally shrinking the base material layer 1 after dicing, and semiconductor chips (semiconductor elements) can be easily recovered.
The surface of the base material layer 1 may be subjected to a conventional surface treatment in order to improve adhesion to an adjacent layer, retention, and the like. Examples of such surface treatments include chemical or physical treatments such as chromic acid treatment, ozone exposure, flame exposure, high-voltage electric shock exposure, and ionizing radiation treatment, and coating treatments with a primer.
The thickness of the base material layer 1 is preferably 1 μm or more and 1000 μm or less, more preferably 10 μm or more and 500 μm or less, still more preferably 20 μm or more and 300 μm or less, particularly preferably 30 μm or more and 200 μm or less.
The thickness of the base material layer 1 can be obtained by using a digital dial gauge (model R-205, manufactured by peaccock corporation) in the same manner as the thickness of the conductive sheet 3.
The substrate layer 1 may contain various additives. Examples of the various additives include colorants, fillers, plasticizers, antioxidants, surfactants, and flame retardants.
The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer 2 is not particularly limited, and for example, a general pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive and a rubber pressure-sensitive adhesive can be used. The pressure-sensitive adhesive is preferably an acrylic adhesive containing an acrylic polymer as a base polymer, in view of detergency and the like for cleaning electronic parts such as semiconductor wafers and glass which are susceptible to contamination by an organic solvent such as ultrapure water or alcohol.
Examples of the acrylic polymer include acrylic polymers using 1 or 2 or more of alkyl (meth) acrylate and cycloalkyl (meth) acrylate as monomer components. Examples of the alkyl (meth) acrylate include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl, eicosyl and the like, and in particular, straight-chain or branched alkyl esters having from 1 to 30 carbon atoms, especially from 4 to 18 carbon atoms, may be used. As the cycloalkyl (meth) acrylate, for example, cyclopentyl ester, cyclohexyl ester, and the like can be used.
The term "meth" refers to at least one of an acrylate and a methacrylate, and the term "meth" in the present invention refers to the same as the above.
For the purpose of modifying the cohesive force, heat resistance, and the like, the acrylic polymer may contain a unit corresponding to another monomer component copolymerizable with the alkyl (meth) acrylate or cycloalkyl (meth) acrylate, as needed. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; anhydride monomers such as maleic anhydride and itaconic anhydride; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate; sulfonic acid-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acryloxynaphthalene sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloxynaphthalene sulfonic acid; phosphate group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; acrylamide, acrylonitrile, and the like. These copolymerizable monomer components may be used in an amount of 1 or 2 or more. The amount of these copolymerizable monomers used is preferably 40% by mass or less of the total monomer components.
The acrylic polymer may contain a polyfunctional monomer or the like as a comonomer component, if necessary, for crosslinking. Examples of such polyfunctional monomers include 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, dipentaerythritol hexa (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and urethane (meth) acrylate. These polyfunctional monomers may be used in an amount of 1 or 2 or more. The amount of the polyfunctional monomer used is preferably 30 mass% or less based on the total monomer components, from the viewpoint of adhesion properties and the like.
The acrylic polymer can be obtained by polymerizing a single monomer or a mixture of 2 or more monomers. The polymerization may be carried out by any method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. The content of the low molecular weight substance is preferably small in terms of preventing contamination of the cleaned adherend and the like. From this point of view, the number average molecular weight of the acrylic polymer is preferably 30 ten thousand or more, more preferably about 40 ten thousand to 300 ten thousand.
In order to increase the number average molecular weight of the acrylic polymer or the like as the base polymer, an external crosslinking agent may be added to the adhesive as appropriate. Specific examples of the external crosslinking method include the following: adding a crosslinking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound, and a melamine crosslinking agent, and reacting. In the case of using an external crosslinking agent, the amount to be used is appropriately determined in consideration of the balance with the base polymer to be crosslinked and the use as an adhesive. In general, the external crosslinking agent is preferably blended in an amount of about 5 parts by mass or less, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the base polymer.
In addition to the above components, the adhesive may contain various known additives such as a tackifier and an antioxidant, if necessary.
The adhesive layer 2 may be formed of a radiation curable adhesive. The radiation curable adhesive can increase the crosslinking degree by irradiation of radiation such as ultraviolet rays, and can easily reduce the adhesive force. That is, by forming the adhesive layer 2 with the radiation curable adhesive, the conductive sheet 3 is sufficiently adhered to the adhesive layer 2 without irradiating the adhesive layer 2 with radiation before dicing, and after dicing, the adhesive force of the adhesive layer 2 is reduced by irradiating the adhesive layer 2 with radiation, whereby the semiconductor chip (semiconductor element) can be easily picked up (recovered).
The radiation curable adhesive may be used without particular limitation as long as it has a radiation curable functional group such as a carbon-carbon double bond and exhibits adhesion. Examples of the radiation curable adhesive include additive type radiation curable adhesives obtained by mixing a radiation curable monomer component or oligomer component with a conventional pressure sensitive adhesive such as an acrylic adhesive or a rubber adhesive.
Examples of the radiation-curable monomer component include urethane (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1, 4-butanediol di (meth) acrylate. The radiation-curable oligomer component may be various oligomers such as urethane, polyether, polyester, polycarbonate, polybutadiene, etc., and the molecular weight thereof is preferably in the range of about 100 to 30000. The amount of the radiation-curable monomer component and the amount of the radiation-curable oligomer component to be blended are preferably such that the adhesive force of the adhesive layer 2 can be suitably reduced after irradiation with radiation. In general, the amount of the radiation-curable monomer component and the radiation-curable oligomer component to be blended is, for example, preferably 5 to 500 parts by mass, and more preferably 40 to 150 parts by mass, based on 100 parts by mass of the base polymer such as an acrylic polymer constituting the adhesive.
In addition to the additive type radiation curable adhesive, an internal type radiation curable adhesive using a substance having a carbon-carbon double bond in a polymer side chain or a main chain or at a main chain end as a base polymer may be used as the radiation curable adhesive. The internal type radiation curable adhesive does not need to contain an oligomer component or the like as a low molecular component, or the content of the oligomer component or the like is small. Therefore, when the internal-type radiation-curable adhesive is used, the oligomer component and the like can be prevented from moving in the adhesive layer 2 with the passage of time. As a result, the adhesive layer 2 can have a relatively stable layer structure.
The base polymer having a carbon-carbon double bond is not particularly limited as long as it has a carbon-carbon double bond and has adhesiveness. As such a base polymer, a base polymer having an acrylic polymer as a basic skeleton is preferable. The basic skeleton of the acrylic polymer includes the acrylic polymer described above.
The method of introducing a carbon-carbon double bond into the acrylic polymer is not particularly limited, and various methods can be employed, and if a method of introducing a carbon-carbon double bond into a polymer side chain is employed, molecular design is easy. For example, the following methods are mentioned: after copolymerizing a monomer having a functional group with an acrylic polymer in advance, a compound having a functional group capable of reacting with the functional group and a carbon-carbon double bond is subjected to a condensation reaction or an addition reaction while maintaining the radiation curability of the carbon-carbon double bond.
Examples of combinations of these functional groups include a carboxylic acid group and an epoxy group, a carboxylic acid group and an aziridine group, a hydroxyl group and an isocyanate group, and the like. Among these functional groups, a combination of a hydroxyl group and an isocyanate group is preferable in terms of ease of reaction tracking. In addition, any of these functional groups may be located on the acrylic polymer side or on the compound side having a carbon-carbon double bond as long as the combination is such that the acrylic polymer having a carbon-carbon double bond is formed, but in the case of the preferred combination, it is preferable that the acrylic polymer has a hydroxyl group and the compound having a carbon-carbon double bond has an isocyanate group. In this case, examples of the isocyanate compound having a carbon-carbon bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, m-isopropenyl- α, α -dimethylbenzyl isocyanate and the like. The acrylic polymer may be a copolymer of the hydroxyl group-containing monomer, an ether compound such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, or diethylene glycol monovinyl ether.
The internal-type radiation-curable adhesive may be used alone with the base polymer having a carbon-carbon double bond (particularly, an acrylic polymer), or may be blended with the radiation-curable monomer component or the radiation-curable oligomer component to such an extent that the properties do not deteriorate. In general, the radiation-curable oligomer component and the like are contained in a range of 30 parts by mass or less relative to 100 parts by mass of the base polymer, and the radiation-curable oligomer component and the like are preferably contained in a range of 1 to 10 parts by mass.
In the case of curing by ultraviolet rays or the like, the radiation curable adhesive contains a photopolymerization initiator. Examples of the photopolymerization initiator include α -ketol compounds such as 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α -hydroxy- α, α' -dimethyl acetophenone, 2-methyl-hydroxy propiophenone, and 1-hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone, and 2-methyl-1- [4- (methylthio) -phenyl ] -2-morpholinopropane-1; benzoin ether compounds such as benzoin diethyl ether, benzoin isopropyl ether, anisoin methyl ether, and the like; ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-benzophenone-1, 1-propanedione-2- (O-ethoxycarbonyl) oxime; benzophenone-based 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; a halogenated ketone; acyl phosphine oxides; acyl phosphonates and the like. The amount of the photopolymerization initiator to be blended is, for example, 0.05 to 20 parts by mass per 100 parts by mass of the base polymer such as the acrylic polymer constituting the adhesive.
Examples of the radiation curable adhesive include rubber adhesives, acrylic adhesives, and the like disclosed in japanese unexamined patent publication No. 60-196956, which contain an addition polymerizable compound having 2 or more unsaturated bonds, a photopolymerizable compound such as an alkoxysilane having an epoxy group, and a photopolymerization initiator such as a carbonyl compound, an organic sulfur compound, a peroxide, an amine, and an onium salt compound.
When the curing is inhibited by oxygen during irradiation with radiation, it is desirable to block the surface of the radiation curable pressure-sensitive adhesive layer 2 by some method with oxygen (air). For example, a method of coating the surface of the pressure-sensitive adhesive layer 2 with a release film; a method of irradiating a nitrogen atmosphere with a radiation such as ultraviolet rays, and the like.
The thickness of the pressure-sensitive adhesive layer 2 is not particularly limited, but is preferably 1 to 50 μm, more preferably 2 to 30 μm, from the viewpoint of preventing chip cut surface defects and securing and retaining properties of the conductive sheet 3.
The dicing die bonding film 20 of the present embodiment is mounted on a semiconductor wafer having a height difference portion such as a TAIKO (registered trademark) wafer using a film attaching device or the like, for example.
Hereinafter, an example of mounting the dicing die bonding film 20 of the present embodiment on a semiconductor wafer having a height difference portion using a film attaching apparatus will be described with reference to fig. 2A to 2F.
As shown in fig. 2A to 2E, the film mounting apparatus 100 includes: a housing chamber 101 formed in a circular shape in plan view, having a housing space S formed by a housing chamber bottom wall portion 101a and a housing chamber side wall portion 101b extending vertically upward from an end edge of the housing chamber bottom wall portion 101a, and being open on an upper side; a stage 102 which is disposed in the accommodation space S of the accommodation chamber 101, is formed in a circular shape in a plan view, and is configured to be capable of placing an adherend of a film on the upper surface side; a lifting device 103 which is installed on the lower surface side of the stage 102 so as to be capable of lifting and lowering in a state of penetrating a part of the housing bottom wall portion 101a of the housing 101; and a lid 104 that is disposed above the housing chamber 101, is formed in a circular shape in plan view, includes a lid bottom wall 104a and a lid side wall 104b that extends vertically downward from an end edge of the lid bottom wall 104a, and is configured such that the housing chamber 101 is closed by bringing a lower surface side of the lid side wall 104b into contact with an upper surface side of the housing chamber side wall 101 b.
As described above, since the housing chamber 101 and the lid 104 are formed in a circular shape in plan view, in the example shown in fig. 2A to 2E, the housing chamber side wall portion 101b extends vertically upward so as to surround the end edge of the housing chamber bottom wall portion 101a, and the lid side wall portion 104b extends vertically downward so as to surround the end edge of the lid bottom wall portion 104 a.
The housing chamber 101 includes a housing chamber seal P1, the housing chamber seal P1 is provided on the housing chamber side wall 101b so as to surround the housing chamber side wall 101b, and the lid 104 includes a lid seal P2, the lid seal P2 is provided on the lid side wall 104b so as to surround the lid side wall 104 b.
As the housing chamber seal P1 and the lid seal P2, rubber seals are preferably used.
The film mounting device 100 is not necessarily provided with both the housing chamber seal P1 and the lid seal P2, and may be provided with at least either one.
Further, in the example shown in fig. 2A to 2E, the stage 102 includes: a stage bottom wall portion 102a; and a stage side wall portion 102b provided so as to protrude vertically upward from an end edge of the stage bottom wall portion 102 a.
As described above, since the stage 102 is formed in a circular shape in plan view, in the example shown in fig. 2A to 2E, the stage side wall portion 102b is provided so as to protrude vertically upward so as to surround the end edge of the stage bottom wall portion 102A.
The film mounting apparatus 100 includes a decompression pump (not shown) for decompressing the storage space S in a state where the storage chamber 101 is closed by the cover 104.
The film mounting apparatus 100 includes an opening valve (not shown) for releasing the depressurized state of the storage space S.
The method for mounting the dicing die bonding film on the semiconductor wafer having the height difference portion includes the steps of: a wafer mounting step of mounting a semiconductor wafer SW having a height difference on the upper surface side of the stage 102; a dicing die bonding film disposing step of disposing the dicing die bonding film 20 on an upper edge of the housing chamber side wall portion 101b in the housing chamber 101 so as to cover a part of the upper opening portion; a sealing step of closing the housing chamber 101 with the lid 104 from above the dicing die-bonding film 20; a depressurizing step of depressurizing the accommodation space S of the accommodation chamber 101 to bend a part of the dicing die-bonding film 20 downward; a dicing die bonding film contacting step of raising the stage 102 to bring the semiconductor wafer SW having the height difference portion into contact with the dicing die bonding film 20 in a bent state; and a dicing die bonding film bonding step of bonding the semiconductor wafer SW having the height difference portion to the dicing die bonding film 20 in a bent state by releasing the reduced pressure state of the accommodation space S of the accommodation chamber 101.
In the wafer mounting step, as shown in fig. 2A, the semiconductor wafer SW having the height difference portion is mounted on the upper surface side of the stage 102 so that the side having the height difference portion SW1 is the upper side.
Specifically, in the wafer mounting step, the semiconductor wafer SW having the height difference portion is mounted on the upper surface side of the stage 102 by mounting the height difference portion SW1 on the stage side wall portion 102 b.
Here, the surface on the side not having the level difference portion SW1 is the surface on which the circuit is to be formed (i.e., the circuit formation surface), but as described above, by placing the level difference portion SW1 on the stage side wall portion 102b, the circuit formation surface can be prevented from directly contacting the stage bottom wall portion 102a in the stage 102, and therefore the damage to the circuit formation surface can be suppressed.
In the dicing die bonding film disposing step, as shown in fig. 2B, the dicing die bonding film 20 is disposed on the housing chamber seal P1 provided on the housing chamber side wall portion 101B of the housing chamber 101 so that the conductive sheet 3 side faces the semiconductor wafer SW having the height difference portion.
In the dicing die bonding film disposing step, the dicing die bonding film 20 is disposed on the housing chamber seal P1 provided on the housing chamber side wall portion 101b of the housing chamber 101 so that the dicing die bonding film 20 covers the semiconductor wafer SW having the height difference portion (so that the dicing die bonding film 20 overlaps the semiconductor wafer SW having the height difference portion).
Since the dicing die-bonding film 20 is stored in a state of being wound in a roll, the dicing die-bonding film wound from the state of being wound in a roll is disposed on the housing chamber seal member P1, but in fig. 2B, etc., illustration of the case of being wound from the state of being wound in a roll is omitted.
In the sealing step, as shown in fig. 2C, the cover 104 is brought into contact with the base material layer 1 side of the dicing die-bonding film 20 from above, thereby closing the housing chamber 101 and sealing it.
Specifically, in the sealing step, as shown in fig. 2C, the lid seal P2 provided on the lid side wall 104b of the lid 104 is brought into contact with the base material layer 1 side of the dicing die bonding film 20, thereby closing the housing chamber 101 and sealing it.
In the depressurizing step, as shown in fig. 2D, the accommodating space S of the accommodating chamber 101 is depressurized by the depressurizing pump (not shown), and a part of the dicing die-bonding film 20 is bent downward.
Specifically, the pressure-reducing pump is used to reduce the pressure in the storage space S, not in the space S 'formed between the dicing die-bonding film 20 and the cover 104, so that a pressure difference is generated between the space S' and the storage space S, and the dicing die-bonding film 20 is pulled toward the storage space S by the pressure difference, and is bent downward.
In the depressurizing step, the storage space S of the storage chamber 101 is preferably depressurized to 100Pa or less.
In the dicing die-bonding film contacting step, as shown in fig. 2E, the carrier 102 is raised by the elevating device 103 to bring the semiconductor wafer SW having the height difference portion into contact with the dicing die-bonding film 20 in a bent state.
In the dicing die-bonding film contacting step, the stage 102 is preferably raised at a speed of 0.1 cm/min to 10 cm/min.
Here, as shown in fig. 2E, a part of the dicing die-bonding film 20 becomes a curved state.
Therefore, the dicing die-bonding film 20 is brought into contact with the level difference portion SW1 of the semiconductor wafer SW having the level difference portion, but is not in a state of sufficiently following the level difference portion SW1, but is brought into a state of generating a relatively large void (a void formed from the end edge of the level difference portion SW1 to the inside of more than 500 μm from the end edge) from the end edge of the level difference portion SW1 toward the center of the semiconductor wafer SW having the level difference portion.
In the dicing die-bonding film bonding step, as shown in fig. 2F, the opening valve (not shown) is opened, and the depressurized state of the accommodation space S of the accommodation chamber 101 is released, so that the dicing die-bonding film 20 in contact with the level difference portion SW1 of the semiconductor wafer SW having the level difference portion is further deformed, and the dicing die-bonding film 20 follows the level difference portion SW1.
As described above, in the dicing die-bonding film 20 of the present embodiment, the viscosity of the conductive sheet 3 at 70 ℃ is 10kpa·s or more and 10000kpa·s or less and the elongation at break at 70 ℃ is 110% or more, so that the conductive sheet can sufficiently follow the stepped portion SW1.
The dicing die bonding film bonding step may be performed under atmospheric pressure while releasing the reduced pressure, or may be performed under pressurized conditions.
In the case where the dicing die bonding film bonding step is performed under pressurized conditions, the dicing die bonding film bonding step may be performed by providing the film mounting apparatus 100 with a pressurizing mechanism and pressurizing the film by the pressurizing mechanism.
Alternatively, the dicing die-bonding film bonding step may be performed as follows: the dicing die bonding film 20 having the height difference portion and the semiconductor wafer SW1 in contact with the height difference portion is taken out from the film mounting apparatus 100, placed in a pressurizing apparatus different from the film mounting apparatus 100, and then pressurized in the pressurizing apparatus, whereby the dicing die bonding film bonding process is performed.
When the dicing die-bonding film bonding step is performed under pressurized conditions, the pressurized conditions include a pressure under conditions of 0.2MPa to 0.7MPa for 10 seconds to 3 minutes.
In the case where the dicing die-bonding film bonding step is performed under pressure, the pressure may be performed under heating. The heating conditions include heating at a temperature of 40 ℃ or higher and 90 ℃ or lower.
After the dicing die bonding film bonding step, the semiconductor wafer SW having the height difference portion is cut at a position inside the height difference portion SW1 to form a flat semiconductor wafer (hereinafter, referred to as a flat semiconductor wafer with a dicing die bonding film) in a state where the dicing die bonding film 20 is mounted.
The flat semiconductor wafer with the dicing die bonding film is diced into a plurality of semiconductor chips (hereinafter referred to as semiconductor chips with dicing die bonding film) on which the dicing die bonding film 20 is mounted by dicing with a blade or the like.
Then, among the semiconductor chips with dicing die bonding films, the semiconductor chip mounted with the conductive sheet 3 (hereinafter, referred to as a semiconductor chip with conductive sheet) is obtained by separating the conductive sheet 3 from the adhesive layer 2.
The semiconductor chip with the conductive sheet thus obtained is mounted on an adherend such as a metal lead frame and used as a component of a semiconductor device.
As described above, the conductive sheet according to the present embodiment is suitable for use on a surface of a semiconductor wafer having a level difference portion, such as a TAIKO (registered trademark) wafer, on which the level difference portion is formed, and is particularly suitable for use on a surface of a semiconductor wafer having a plurality of steps of level difference portions, on which the level difference portion is formed.
The conductive sheet according to the present embodiment is suitable for use in a power semiconductor device for mounting a power semiconductor chip on a substrate.
The conductive sheet and dicing die-bonding film according to the present embodiment are configured as described above, and therefore have the following advantages.
(1) A conductive sheet comprising a binder resin and conductive particles,
the conductive sheet has a viscosity of 10 to 10000kPa s at 70 ℃,
the elongation at break at 70 ℃ is 110% or more.
According to this configuration, the conductive sheet can sufficiently follow the height difference portion when mounted on the semiconductor wafer having the height difference portion.
(2) The conductive sheet according to the above (1), wherein,
the content of the conductive particles is 85 mass% or more and 97 mass% or less.
According to this configuration, the conductive sheet can sufficiently follow the height difference portion and exhibit sufficient conductivity when mounted on a semiconductor wafer having the height difference portion.
(3) The conductive sheet according to the above (1) or (2), wherein,
the conductive particles include at least 1 selected from the group consisting of silver particles, copper particles, silver oxide particles, and copper oxide particles.
According to this configuration, the conductive sheet can sufficiently follow the height difference portion and exhibit sufficient electrical conductivity and thermal conductivity when mounted on a semiconductor wafer having the height difference portion.
(4) The conductive sheet according to any one of the above (1) to (3), wherein,
the binder resin comprises a thermosetting resin.
According to this configuration, the conductive sheet can be thermally cured, so that the adhesion to an adherend (for example, a metal lead frame or the like) can be improved.
(5) The conductive sheet according to any one of the above (1) to (4),
it also contains volatile components with a volatilization initiation temperature of more than 100 ℃.
According to this configuration, since the conductive sheet further contains a volatile component having a volatilization initiation temperature of 100 ℃ or higher, the volatile component can be volatilized relatively sufficiently when the conductive sheet is heated at a temperature of 150 to 200 ℃ and thermally cured.
This can relatively sufficiently reduce the volume of the conductive sheet.
Further, the conductive particles are in close positional relationship with each other in the conductive sheet according to the degree of volume reduction of the conductive sheet, so that a heat conduction path is easily formed in the conductive sheet by the conductive particles.
This can relatively improve the thermal conductivity of the conductive sheet.
(6) A dicing die bonding film, comprising:
dicing tape having adhesive layer laminated on base layer, and method for manufacturing dicing tape
A conductive sheet laminated on the adhesive layer of the dicing tape,
the conductive sheet according to any one of the above (1) to (5).
According to this configuration, the dicing die bonding film can sufficiently follow the level difference portion when mounted on the semiconductor wafer having the level difference portion via the conductive sheet.
The conductive sheet and dicing die-bonding film according to the present invention are not limited to the above-described embodiments. The conductive sheet and dicing die-bonding film of the present invention are not limited to the above-described effects. The conductive sheet and dicing die-bonding film of the present invention may be variously modified within a range not departing from the gist of the present invention.
Examples
The present invention will be described more specifically with reference to examples. The following examples are given to illustrate the invention in more detail, but do not limit the scope of the invention.
Example 1
A varnish was prepared by stirring and mixing a mixture containing each material in the mass ratio shown in example 1 of Table 1 below for 3 minutes using a mixer (trade name: HM-500, manufactured by Kirschner Co., ltd.).
The varnish was applied to one surface of a release film (trade name: MRA38, manufactured by Mitsubishi chemical corporation, thickness 38 μm), and then dried at 100℃for 2 minutes to obtain a conductive sheet having a thickness of 30. Mu.m.
The following materials were used as the materials shown in table 1 below.
Phenolic resin
MEHC-7851S (biphenyl phenol resin, phenol equivalent 209 g/eq) manufactured by Ming He chemical Co., ltd
Solid epoxy resin
KI-3000-4 (cresol novolac type multifunctional epoxy resin, epoxy equivalent 200 g/eq) manufactured by Nippon Kagaku Co., ltd
Liquid epoxy resin
EXA-4816 (aliphatic modified bisphenol A type epoxy resin (2 functional type), epoxy equivalent 403g/eq, manufactured by DIC Co., ltd.)
Silver (Ag) coated copper (Cu) particles
Particles having a silver layer of 10 mass% coated on flat copper particles (average particle diameter 3.5 μm, amorphous; hereinafter referred to as 10% coated silver-coated copper particles)
Silver (Ag) particles
Aggregated nanoparticles (amorphous, aggregate having an average particle diameter of 1.8 μm; hereinafter referred to as aggregated silver particles)
Volatile material (isobornyl cyclohexanol (MTPH))
MTPH manufactured by Nippon Terpene Chemicals Co
Acrylic resin solution
Teisan Resin SG-70L (solvent, MEK and toluene, solid content 12.5%, glass transition temperature-13 ℃ C., mass average molecular weight 90 ten thousand, acid value 5mg/KOH, carboxyl group-containing acrylic copolymer) manufactured by Nagase ChemteX Co
Coupling agent
KBE-846 (bis (triethoxysilylpropyl) tetrasulfide from Xinyue chemical industries Co., ltd.)
Catalyst
TPP-K (tetraphenylphosphine borided by Tetrap-tolyl) manufactured by North chemical Co., ltd
Solvent(s)
Methyl Ethyl Ketone (MEK)
The mass ratio (parts by mass) of the thermoplastic resin (acrylic resin) to 100 parts by mass of the thermosetting resin (epoxy resin (solid and liquid) and phenolic resin), the mass ratio (parts by mass) of the volatile material (isobornyl cyclohexanol (MTPH)) to 100 parts by mass of the thermosetting resin, and the mass ratio (parts by mass) of the conductive particles to 100 parts by mass of the thermosetting resin are shown in table 2 below.
The mass ratio of the silver-coated copper particles and the silver particles in 100 parts by mass of the conductive particles (silver-coated copper particles and silver particles) is shown in table 3 below.
Example 2
A conductive sheet of example 2 was obtained in the same manner as in example 1, except that the liquid epoxy resin was made into YL980 manufactured by mitsubishi chemical corporation, the silver particles were made into silver particles surface-treated with a fatty acid-based coating agent (fatty acid-treated silver particles; the particle shape was spherical; hereinafter referred to as fatty acid-treated silver particles), the silver-coated copper particles were made into particles in which 20 mass% of a silver layer was coated on the spherical copper particles (particle shape was spherical; hereinafter referred to as 20% of coated silver-coated copper particles), and a mixture containing the respective materials in the mass ratio shown in example 2 of table 1 below was obtained.
Example 3
A conductive sheet of example 3 was obtained in the same manner as in example 1, except that a liquid epoxy resin was used as YL980 manufactured by mitsubishi chemical corporation, silver particles were used as fatty acid-treated silver particles, silver-coated copper particles were used as 20% coated silver-coated copper particles, and a mixture containing the respective materials in the mass ratio shown in example 3 of table 1 below was obtained.
Example 4
A conductive sheet of example 4 was obtained in the same manner as in example 1, except that a liquid epoxy resin was used as YL980 manufactured by mitsubishi chemical corporation, silver particles were used as silver particles surface-treated with an epoxy-based coating agent (epoxy-treated silver particles; the particle shape was spherical; hereinafter referred to as epoxy-treated silver particles), and a mixture containing each material was obtained in the mass ratio shown in example 4 of table 1 below.
Comparative example 1
A conductive sheet of comparative example 1 was obtained in the same manner as in example 1 except that a liquid epoxy resin was used as YL980 manufactured by mitsubishi chemical corporation, silver particles were used as fatty acid-treated silver particles, silver-coated copper particles were used as 20% coated silver-coated copper particles, and a mixture containing the respective materials in mass ratios shown in comparative example 1 of table 1 below was obtained.
TABLE 1
Unit (B) Example 1 Example 2 Example 3 Example 4 Comparative example 1
Phenolic resin Parts by mass 2.03 1.05 0.65 1.05 0.58
Solid epoxy resin Parts by mass 1.64 0.68 0.42 0.67 0.47
Liquid epoxy resin Parts by mass 0.7 0.29 0.18 0.29 0.08
Ag-coated Cu particles Parts by mass 15 12.6 14.14 20.66 15.95
Ag particles Parts by mass 6.31 29.4 33 48.21 37.22
Volatile Material (MTPH) Parts by mass - - 0.62 1.73 0.56
Acrylic seriesResin solution Parts by mass 15 16.17 10.01 16.13 9.04
Coupling agent Parts by mass 0.164 0.123 0.095 0.176 0.086
Catalyst Parts by mass 0.019 0.012 0.007 0.003 0.007
MEK Parts by mass 9 4.5 12 10.5 18.5
TABLE 2
Thermal conductivity of conductive sheet
The conductive sheets of each example were heat-cured by treating them at 200℃for 1 hour while applying a pressure of 0.5MPa to them by an autoclave apparatus. For the thermally cured conductive sheets of each example, the thermal conductivity was calculated by the following formula.
Thermal conductivity (W/m·k) =thermal diffusivity (m 2 Specific heat (J/g. DEG C.) times specific gravity (g/cm) 3 )
Thermal diffusivity alpha (m) 2 S) by TWA method (temperature wave thermal analysis, measurement apparatus: ai-Phase Mobile, manufactured by ai-Phase Co.).
Specific heat Cp (J/g. Cndot. ℃ C.) was measured by DSC method. Specific heat was measured using DSC6220, manufactured by SII Nanotechnology company, at a temperature rise rate of 10 ℃/min and at a temperature in the range of 20 to 300 ℃, and based on the obtained data, specific heat was calculated by a method described in JIS Manual (specific heat capacity measurement method K-7123).
Specific gravity was measured by archimedes method.
The results of calculating the thermal conductivity of the thermally cured conductive sheets of each example are shown in table 3 below.
< viscosity at 70 ℃ eta >
For each example, the viscosity η at 70 ℃ was measured using a rheometer (Thermo Fisher Scientific inc. Manufactured by rotary rheometer HAAKE MARS).
Specifically, measurement was performed by using a Gap value of 250 μm, a frequency of 1Hz, and a strain amount of 0.1% and reading an indication value of 70℃when the temperature was raised from 30℃to 180℃at a temperature-raising rate of 10℃per minute.
The results are shown in table 3 below.
< elongation at break at 70 ℃ Bpe >
For each example, the elongation at break Bpe at 70℃was measured using a tensile tester (model "AGS-X" manufactured by Shimadzu corporation).
Specifically, the measurement was performed as follows.
(1) A conductive sheet having a width of 10mm, a length of 30mm and a thickness of 200 μm was prepared.
(2) Polyimide tapes were attached to both longitudinal end sides of the conductive sheet to obtain a sample. Specifically, in the above-mentioned conductive sheet, a polyimide tape was attached to a region extending from the upper edge in the longitudinal direction to a distance of 10mm from the upper edge in the longitudinal direction, and a polyimide tape was attached to a region extending from the lower edge in the longitudinal direction to a distance of 10mm from the lower edge in the longitudinal direction, so that a sample was obtained.
(3) The upper end side of the sample in the longitudinal direction is mounted on one chuck of the tensile testing machine, and the lower end side of the sample in the longitudinal direction is mounted on the other chuck of the tensile testing machine.
(4) After the tensile tester equipped with the sample was placed in a constant temperature bath, the temperature in the constant temperature bath was raised to 70 ℃.
(5) After 3 minutes from the temperature in the constant temperature bath reaching 70 ℃, the test piece was stretched in the longitudinal direction at a distance of 10mm between chucks and a stretching speed of 50 mm/min, and the data obtained in the stretching test were plotted on a graph having a horizontal axis of travel (in mm) and a vertical axis of test force (tensile strength; in N).
(6) In the graph, the time at which the test force reached the maximum was regarded as the time at which the conductive sheet broke, and the stroke value at which the test force reached the maximum was read, divided by the effective length of the conductive sheet (10 mm; length of the portion to which the polyimide tape was not attached), and multiplied by 100, thereby calculating the elongation at break at 70 ℃.
The results are shown in table 3 below.
< follow-up Property for height difference portion >)
For each example, the following property to the level difference portion was evaluated by using a vacuum wafer mounter (vacuum mounter MSA840VIII, manufactured by niton corporation).
Specifically, the evaluation was performed as follows.
(1) A1 st die having a planar size of 10mm×10mm and a thickness of 100 μm was fixed to one surface of a slide glass using a 1 st die bonding film (trade name "EM-310V", manufactured by Nito electric Co., ltd., thickness of 7 μm), and a 2 nd die having a planar size of 9mm×9mm and a thickness of 300 μm was fixed to an exposed surface of the 1 st die using a 2 nd die bonding film (trade name "EM-310V", manufactured by Nito electric Co., ltd., thickness of 7 μm), to thereby obtain a die laminate.
The 2 nd die is fixed to the exposed surface of the 1 st die so that the center portion of the 2 nd die coincides with the center portion of the 1 st die.
In addition, the bare chip stacks formed 1 group on the glass slide.
(2) The above bare chip laminate was fixed on an adhesive layer of dicing tape (trade name "ELP V-12SR" manufactured by nito corporation) together with a wafer ring, to obtain a sample.
The slide side of the bare chip laminate was fixed to the adhesive layer of the dicing tape.
(3) The sample is placed on a stage provided in a housing chamber of the vacuum wafer mounter so that the dicing tape side is the lower side. The stage was preheated to 70 ℃.
(4) The dicing die bonding film is disposed on the upper edge of the side wall of the housing chamber so as to cover the bare chip laminate in the sample and so that the conductive sheet side faces the bare chip laminate.
In the dicing die bonding film, the die bonding film is a film obtained by bonding the conductive sheet of each example to an adhesive layer of dicing tape (trade name "ELP V-12SR" manufactured by nito corporation).
(5) After closing the cover body of the vacuum wafer surface mount machine, the accommodating space of the accommodating chamber is depressurized to 0MPa.
(6) The vacuum state of the accommodating space of the accommodating chamber was released, the vacuum wafer mounter was placed in an autoclave, and then the vacuum wafer mounter was pressurized at a temperature of 70 ℃ for 1 minute under 0.5 MPa.
(7) The bare chip laminate was taken out from the vacuum wafer mounter, and observed from the slide glass side by a microscope, and it was confirmed how much distance from the edge of the 1 st bare chip was formed.
The following property to the height difference portion is determined based on the following criteria.
Preferably: a void is formed from the edge of the 1 st bare chip to a distance of 500 μm or less from the edge.
The method cannot: a void is formed from the end edge of the 1 st die to a distance exceeding 500 μm from the end edge.
The results of evaluating the following property with respect to the height difference portion are shown in table 3 below.
TABLE 3
As is clear from table 3, the conductive sheet of each example had a value of the viscosity η at 70 ℃ in a range of 10kpa·s to 10000kpa·s, and a value of the elongation at break Bpe at 70 ℃ of 110% or more, and all of the following properties of the stepped portion were evaluated as excellent, and the stepped portion could be sufficiently followed.
In contrast, it was found that the conductive sheet of comparative example 1 had a viscosity η at 70 ℃ of more than 10000kpa·s and an elongation at break Bpe at 70 ℃ of less than 110%, and the following property of the stepped portion was evaluated as insufficient, and the stepped portion could not be sufficiently followed.
From the results, it was found that the conductive sheet can sufficiently follow the level difference portion in the semiconductor wafer having the level difference portion by further setting the viscosity η at 70 ℃ to 10kpa·s or more and 10000kpa·s or less and setting the elongation at break at 70 ℃ to 110% or more in addition to the binder resin and the conductive particles contained in the conductive sheet.
As is clear from table 3, the thermal conductivity after heat curing of the conductive sheets of examples 2 to 5 was a sufficient value exceeding 1W/m·k, and the thermal conductivity after heat curing of the conductive sheets of examples 2 to 5 was a more sufficient value exceeding 5W/m·k, and in particular, the thermal conductivity after heat curing of the conductive sheets of examples 3 to 5 was a more sufficient value exceeding 20W/m·k.
Description of the reference numerals
1a base material layer, 2 an adhesive layer, 3 a conductive sheet, 10 a dicing tape, 20 a dicing die bonding film, 100 a film mounting device, 101a housing chamber, 102 a stage, 103 a lifting device, 104a lid, 101a housing chamber bottom wall portion, 101b housing chamber side wall portion, 104a lid bottom wall portion, 104b lid side wall portion, P1 housing chamber seal, P2 lid seal, S housing space, S' space, SW having a semiconductor wafer of height difference, SW1 height difference portion.

Claims (6)

1. A conductive sheet comprising a binder resin and conductive particles,
the conductive sheet has a viscosity of 10 to 10000kPa s at 70 ℃,
the elongation at break at 70 ℃ is 110% or more.
2. The conductive sheet according to claim 1, wherein the content of the conductive particles is 85 mass% or more and 97 mass% or less.
3. The conductive sheet according to claim 1 or 2, wherein the conductive particles comprise at least 1 selected from the group consisting of silver particles, copper particles, silver oxide particles, and copper oxide particles.
4. The conductive sheet according to any one of claims 1 to 3, wherein the binder resin comprises a thermosetting resin.
5. The conductive sheet according to any one of claims 1 to 4, further comprising a volatile component having a volatilization initiation temperature of 100 ℃ or higher.
6. A dicing die bonding film, comprising:
dicing tape having adhesive layer laminated on base layer, and method for manufacturing dicing tape
A conductive sheet laminated on the adhesive layer of the dicing tape,
the conductive sheet according to any one of claims 1 to 5.
CN202280035889.XA 2021-06-16 2022-03-08 Conductive sheet and dicing die bonding film Pending CN117321744A (en)

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