CN115151419B

CN115151419B - Multilayer release film

Info

Publication number: CN115151419B
Application number: CN202180016988.9A
Authority: CN
Inventors: 吉田直纪
Original assignee: Mitsui Chemicals Tohcello Inc
Current assignee: Mitsui Chemicals Tohcello Inc
Priority date: 2020-02-28
Filing date: 2021-02-22
Publication date: 2024-03-12
Anticipated expiration: 2041-02-22
Also published as: JP7390467B2; JPWO2021172257A1; KR20220143764A; TW202200372A; WO2021172257A1; CN115151419A

Abstract

The invention provides a multilayer release film which has excellent physical properties such as fracture resistance, follow-up property, release property, prevention of side biting, and inhibition of buffer layer exudation. The object is achieved by a multilayer release film comprising a release layer A containing a non-crosslinkable resin and a radical scavenger, and a resin layer B containing a vinyl polymer, wherein the resin layer B is crosslinked by electron beam irradiation, and the contact angle of the release layer A after electron beam irradiation to water is 90 DEG to 130 deg.

Description

Multilayer release film

Technical Field

The present invention relates to a multilayer release film having excellent physical properties such as fracture resistance, follow-up property, release property, prevention of biting of a side surface, and suppression of bleeding out of a cushioning (cushioned) layer; more particularly, the present invention relates to a multilayer release film which can be widely used in a printed circuit board manufacturing process or a semiconductor resin sealing process, a method for manufacturing the same, and uses thereof.

Background

In the case of a release film used in a printed circuit board manufacturing process having improved formability and followability, a multilayer film having a center layer crosslinked by radiation such as electron beam and a release layer (surface layer) not crosslinked by radiation such as electron beam has been disclosed. (patent document 1).

However, there has been pointed out a problem that when an article such as a semiconductor chip (chip) is resin-sealed by compression molding or when a cover lay of a flexible printed board (hereinafter also referred to as "FPC") is applied with pressure, a release film breaks.

[ Prior Art literature ]

[ patent literature ]

Patent document 1 japanese patent application laid-open No. 2012-179827.

Disclosure of Invention

[ problem to be solved by the invention ]

In view of the limitations of the conventional techniques, the present invention has been made to provide a multilayer release film which is more preferably a multilayer release film which can be easily released without causing film breakage, resin chipping, or side biting in the former and which can be easily released without causing film breakage, adhesive bleeding, or buffer layer bleeding in the latter, when a molded article after semiconductor resin sealing or pressing of an FPC is performed in a step of resin sealing an article such as a semiconductor chip or a cover layer attaching step of an FPC by a compression molding method or a transfer mold molding method.

[ means for solving the problems ]

As a result of diligent research to solve the above-described problems, the present inventors have found that the fracture is caused by degradation of a non-crosslinkable resin constituting a surface release layer due to electron beam irradiation, and further found that the release layer can be prevented from such degradation by containing an appropriate radical scavenger, and completed the present invention.

That is, the present invention is as follows.

[1] A multilayer release film is formed by crosslinking a resin layer B by electron beam irradiation of a multilayer film comprising a release layer A containing a non-crosslinkable resin and a radical scavenger, and a resin layer B containing a vinyl polymer; wherein the contact angle of the release layer A after electron beam irradiation to water is 90 DEG to 130 deg.

[2] The multilayer release film according to [1], wherein the release layer A has a melting point of 200℃or higher as determined by a differential scanning calorimeter.

[3] The multilayer release film according to [1] or [2], wherein the resin contained in the release layer A is at least one selected from the group consisting of an alpha olefin polymer, a polyester, a fluorine-based resin and a polystyrene-based resin.

[4] The multilayer release film according to any one of [1] to [3], wherein the total amount of the radical scavenger is 0.5 to 2.0% by weight relative to the total weight of the release layer a.

[5] The multilayer release film according to any one of [1] to [4], wherein the radical scavenger is selected from the group consisting of hindered amine light stabilizers, phenolic antioxidants, phosphorus antioxidants, polymerization inhibitors, and mixtures thereof.

[6] The multilayer release film according to any one of [1] to [5], wherein the radical scavenger contained in the release layer A contains a hindered amine light stabilizer.

[7] The multilayer release film according to any one of [1] to [5], wherein the radical scavenger contained in the release layer A contains a phenolic antioxidant.

[8] The multilayer release film according to any one of [1] to [5], wherein the radical scavenger contained in the release layer A contains a hindered amine light stabilizer and a phosphorus-based antioxidant.

[9] The multilayer release film according to any one of [3] to [8], wherein the α -olefin polymer contained in the release layer A is poly (4-methyl-1-pentene) and/or a copolymer thereof.

[10] The multilayer release film according to any one of [3] to [8], wherein the polyester contained in the release layer A is polybutylene terephthalate.

[11] The multilayer release film according to any one of [1] to [10], wherein the release layer A is provided on both surface layers and the resin layer B is provided on the core layer.

[12] The multilayer release film according to any one of [1] to [11], which is used in a printed circuit board manufacturing process or a semiconductor resin sealing process.

[13] A multilayer film comprising a release layer A containing a radical scavenger and a non-crosslinkable resin, and a resin layer B containing a vinyl polymer.

[14] A multilayer release film comprising a multilayer film according to [13] and a resin layer B crosslinked by electron beam irradiation; wherein the contact angle of the release layer A after electron beam irradiation to water is 90 DEG to 130 deg.

[ efficacy of the invention ]

The multilayer release film of the present invention can be free from damage and follow-up/release properties at the time of sealing or pressing, can suppress breakage of the film at the time of sealing or pressing, and is of high value in practical use.

Drawings

Fig. 1 is a schematic view showing an example of a resin sealing process of a semiconductor chip (chip) using a multilayer release film according to the present invention.

Fig. 2 is a schematic diagram showing a test method of the present invention in examples and comparative examples, such as a peeling state after molding.

Fig. 3 is a schematic diagram illustrating a test method of the peeling state after attachment in the example/comparative example of the present invention.

Detailed Description

(multilayer Release film)

The present invention provides a multilayer release film, which is formed by subjecting a multilayer film comprising a release layer A containing a non-crosslinkable resin and a radical scavenger and a resin layer B containing a vinyl polymer to electron beam irradiation to crosslink the resin layer B; wherein the contact angle of the release layer A after electron beam irradiation to water is 90 DEG to 130 deg.

The multilayer release film of the present invention is a laminated film comprising a release layer a having release properties for a molded article or a mold and a resin layer B formed by electron beam crosslinking. Another aspect of the present invention is a laminated film having a release layer a on both surface layers and a resin layer B formed by electron beam crosslinking on a core layer. In still another aspect of the present invention, a laminated film has a release layer a on both surface layers, a resin layer B formed by electron beam crosslinking on a core layer, and intermediate layers on both sides of the core layer as desired.

(Release layer A)

The contact angle of the release layer a after electron beam irradiation with water is 90 ° to 130 °, and by having such contact angle, the release layer a has low wettability, and can be easily released without sticking to the cured sealing resin, FPC, or mold surface.

The contact angle of the release layer a with water is more preferably 95 ° to 120 °, more preferably 98 ° to 115 °, still more preferably 100 ° to 110 °.

The contact angle with water of the film surface may be measured by a method common in the art, and can be measured by the method described in the examples of the present application, for example.

The non-crosslinkable resin contained in the release layer a in the present invention is a resin whose elongation at break at normal temperature is reduced to 20% or less after irradiation of an absorbed dose of electron beam of 100kGy at an acceleration voltage of 200kV when compared with the elongation at break before electron beam irradiation, measured by the method described below, and examples of the resin include an alpha-olefin polymer, a polyester, a fluorine-based resin, and a polystyrene-based resin. The non-crosslinkable resin may be used alone or in combination of 1 or 2 or more.

(elongation at break)

A film having a width of 15mm was prepared, 50mm was set between initial chucks (chuck) and the film was stretched at 300mm/min at 23℃to obtain the elongation at break (electron beam irradiation)

For the film sample, electron rays were irradiated at an acceleration voltage of 200kV and at an absorbed dose of 100 kGy.

The carbon number of the α -olefin polymer that can be used in the release layer a is 3 or more, and more preferably 6 or more. As the alpha olefin polymer, there may be exemplified, for example: (4-methyl-1-pentene), polymers of octenes, decenes, or copolymers with other olefin units. Among them, a polymer or copolymer of (4-methyl-1-pentene) is more preferable.

The fluororesin that can be used for the release layer a may be a resin containing a constituent unit derived from tetrafluoroethylene. Can be homopolymers of tetrafluoroethylene or copolymers with other olefins. Examples of other olefins include ethylene. As the monomer constituent unit, a copolymer containing tetrafluoroethylene and ethylene is preferable, and in such a copolymer, the molar ratio of the unit based on tetrafluoroethylene to the unit based on ethylene (TFE/E) is more preferably 80/20 to 40/60.

The polyester which can be used in the release layer a may be exemplified by polybutylene terephthalate or polyethylene terephthalate.

The polystyrene resin that can be used for the release layer a includes homopolymers and copolymers of styrene, and the structural unit derived from styrene contained in the polymer is preferably at least 60% by weight or more, more preferably 80% by weight or more.

The polystyrene resin may be a co-aligned polystyrene or an opposite-aligned polystyrene, but is more preferably a co-aligned polystyrene from the viewpoints of transparency, easy availability, etc., and is more preferably an opposite-aligned polystyrene from the viewpoints of releasability, heat resistance, etc. The polystyrene may be used alone or in combination of 1 kind or 2 or more kinds.

The release layer A in the present invention contains a radical scavenger. More preferably, release layer a contains 0.5 to 2.5 wt% of radical scavenger, more preferably 0.5 to 2.0 wt%, relative to the total weight of release layer a.

When the resin layer B of the release film is irradiated with electron beams, the surface-side release layer is inevitably irradiated, but the non-crosslinkable resin such as an α -olefin polymer including (4-methyl-1-pentene) is structurally susceptible to decomposition by electron beams. By containing the radical scavenger in the above range, radicals generated by electron beam irradiation can be trapped, and degradation can be suppressed.

The radical scavenger in the present invention may be selected from the group consisting of hindered amine light stabilizers (hereinafter also referred to as HALS), phenolic antioxidants, phosphorus antioxidants, polymerization inhibitors, and mixtures of these.

The radical scavenger is more preferably a hindered amine light stabilizer or a phenolic antioxidant. In addition, a combination of a hindered amine light stabilizer and a phosphorus antioxidant is also preferable in terms of maintaining the elongation at break point.

Examples of the Hindered Amine Light Stabilizer (HALS) include a hindered amine light stabilizer having an N-H bond, a hindered amine light stabilizer having an N-R bond (R represents a monovalent hydrocarbon group), and a hindered amine light stabilizer having an N-OR bond (R represents a monovalent hydrocarbon group).

Examples of the hindered amine light stabilizer having an n—h bond include: tetra (2, 6-tetramethyl-4-piperidinyl) butane-1,2,3, 4-tetracarboxylic acid ester (tetra kis (2, 6-tetramethyl-4-piperidyl) butane-1,2,3, 4-tetracarbonate) or Bis (2, 6-tetramethyl-4-piperidinyl) sebacate, can be obtained from ADEKA, inc. under the product name "ADK STAB LA-57" and the product name "ADK STAB LA-77", respectively. The latter is also available from BASF JAPAN, inc.

As the hindered amine light stabilizer having n—r bond (R represents a monovalent hydrocarbon group), R may be mentioned, for example, a hydrocarbon group having carbon number=1 to 10, and among them, R is more preferable when R is a methyl group. Examples of such HALS include: tetra (1, 2, 6-tetramethyl-4-piperidinyl) butane-1,2,3, 4-tetracarboxylic acid ester (tetra kis (1, 2, 6-tetramethyl-4-piperidyl) butane-1,2,3, 4-tetracarbonate) or Bis (1, 2, 6-tetramethyl-4-piperidinyl) sebacate, can be obtained from ADEKA, inc. under the product name "ADK STAB LA-52" and the product name "ADK STAB LA-72", respectively.

Regarding the hindered amine light stabilizer having an N-OR bond (R represents a monovalent hydrocarbon group), R may be, for example, a hydrocarbon group having carbon number=1 to 10. Examples of such HALS include: bis (1-undecyloxy-2, 6-tetramethylpiperidin-4-yl) carbonate, bis (1-octyloxy-2, 6-tetramethyl-4-piperidinyl) sebacate, the former is available from ADEKA corporation under the product name "ADK starb LA-81", and the latter is available from BASF JAPAN corporation under the product name "Tinuvin 123".

Examples of the phenolic antioxidants include Octadecyl-3- (3, 5-Di-tert-butyl-4-hydroxyphenyl) propionate (Octadecyl-3- (3, 5-Di-tert-butyl-4-hydroxyphenyl) -propionate) (product name Irganox1076, BASF JAPAN Co., ltd.), and 2, 6-Di-tert-butyl-4-cresol (product name H-BHT, product name of chemical industry Co., ltd.).

Examples of the phosphorus antioxidant include Tris (2, 4-di-t-butylphenyl) phosphite (Tris (2, 4-di-tert. -butyl phenyl) phosphate) (product name Irgafos168, BASF JAPAN company, inc.).

Examples of the polymerization inhibitor include hydroquinone monomethyl ether, hydroquinone, phenothiazine (phenothiazine), and the like.

The release layer a is more preferably heat-resistant to a temperature of a mold capable of withstanding molding (typically 120 to 180 ℃) or a temperature of FPC at the time of pressing (typically 150 to 190 ℃). From this viewpoint, the melting point of the release layer a is more preferably 200 ℃ or higher. Although the melting point is not particularly limited to an upper limit, the melting point of the crystalline resin which can be obtained is usually not more than 280 ℃.

(resin layer B)

The resin layer B in the present invention contains a vinyl polymer and forms a crosslinked structure by electron beam irradiation. Although the cushioning property can be imparted by the ethylene copolymer, bleeding due to melting of the cushioning layer occurs when pressure is applied while heating at high temperature. Thus, by performing electron beam crosslinking, bleeding can be suppressed while maintaining the cushioning property.

From the viewpoint of traceability of a release film of a printed circuit board or a semiconductor package, or extensibility upon pressing, examples of the vinyl polymer include polyethylene, ethylene- α -olefin copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-cycloolefin copolymer.

(other layers)

The multilayer release film of the present embodiment may have layers other than the release layer a and the resin layer B as long as the object of the present invention is not impaired. For example, an intermediate layer may optionally be provided between the release layer a as both surface layers and the resin layer B as the core layer. The material used for the intermediate layer is not particularly limited as long as it can firmly adhere the release layer a and the resin layer B, and peeling does not occur even in the resin sealing step, the release step, or the pressing step of the FPC.

For example, in the case where release layer A comprises a 4-methyl-1-pentene copolymer, the intermediate layer may also comprise polypropylene, propylene-ethylene copolymer, a blend of polypropylene and polyethylene, a blend of 4-methyl-1-pentene and polyethylene, ethylene copolymer, a blend of release layer and core layer, methylpentene, alpha-olefin copolymer.

The thickness of the intermediate layer is not particularly limited as long as it can improve the adhesion between the release layer a and the resin layer B, but is, for example, 0.5 to 10 μm.

The total thickness of the multilayer release film of the present invention is not particularly limited, but is more preferably, for example, 10 to 300 μm, more preferably 30 to 150 μm, and most preferably 50 to 120 μm. When the total thickness of the multilayer release film is within the above range, the handling property when used as a roll is good, and the amount of waste film is small, so that it is preferable.

(method for producing multilayer Release film)

The multilayer release film of the present invention can be produced by any method.

The multilayer film before crosslinking can be, for example, one that: 1) A method of producing a multilayer film by co-extrusion molding a release layer a and a resin layer B and laminating (co-extrusion molding method); 2) A method (coating method) of coating/drying a molten resin which becomes a resin of the release layer a or the intermediate layer on a film which becomes the resin layer B, or coating/drying a resin solution in which a resin which becomes the release layer a or the intermediate layer has been dissolved in a solvent to produce a release film; 3) The film to be the release layer a and the film to be the resin layer B are produced in advance, and a multilayer film is produced by laminating these films (Laminate method). Then, the obtained multilayer film is subjected to electron beam irradiation and the resin layer B is crosslinked to obtain the multilayer release film of the present invention.

(resin sealing Process)

The multilayer release film of the present invention is used in, for example, a resin sealing process performed according to a compression molding method or a transfer molding method. When a semiconductor chip (chip) or the like is placed in a mold and resin is injected into the mold, the multilayer release film of the present invention can be used between the semiconductor chip (chip) or the like and the inner surface of the mold. By using the multilayer release film of the present invention, peeling failure, generation of burrs (burrs), and the like at the time of peeling from the mold can be effectively prevented.

The resin used in the manufacturing process according to the compression molding method may be either a thermoplastic resin or a thermosetting resin, but thermosetting resins are widely used in the technical field, and particularly epoxy-based thermosetting resins are more preferable.

In the art, a resin used in a manufacturing process according to the transfer molding method is widely used, and in particular, an epoxy-based thermosetting resin is more preferable.

The resin sealing process using the multilayer release film of the present invention can be suitably employed as conventionally disclosed in the art, and is not particularly limited, but for example, in the case of a resin sealing process of a semiconductor chip (chip) according to a compression molding method, it is preferable to sequentially perform the steps 1.to 9 shown in fig. 1.

More specifically, in the "1 film cutting" step, the multilayer release film 11 of the present invention is pulled out from a roll-like roll, and is unwound on an X-Y stage (stage) 13, and cut into a predetermined size. The predetermined size of the multilayer release film 11 is not particularly limited, but is more preferably: the entire surface of a cavity 19c provided in a lower mold 19 used in a resin sealing process is covered, and includes a size for fixing a film 11 between a clamp (clamp) 19b constituting the lower mold 19 and an upper mold 15.

Next, in the step of "2. Frame-type setting", a frame 14 having a shape substantially overlapping the fixing portion is spread on the X-Y stage 13, and is set on the multilayer release film 11 cut to a predetermined size so as to substantially overlap the fixing portion.

Next, in the step "3. Resin metering", a predetermined amount of sealing resin 18 is simultaneously metered and disposed on the multilayer release film 11 and in the frame 14. The amount of the sealing resin 18 is not particularly limited, but is desirably about the same as the volume of the cavity 19c after the "8. Compression" step described later.

Then, in the "4. Resin+film transfer" step, the multilayer release film 11 is transferred from the X-Y stage 13 together with the sealing resin 18 placed on the release film 11 in a state of being adsorbed on the frame 14, and placed on the lower mold 19 to be resin-sealed. In this case, it is preferable that the multilayer release film 11 is disposed so as to cover the cavity 19c provided in the lower mold 19, and the sealing resin 18 disposed on the multilayer release film 11 is disposed on the cavity 19 c.

Next, in the "5 vacuum suction" step, the fixing portion of the multilayer release film 11 is fixed between the frame 14 and the holder 19b constituting the lower mold 19, and the multilayer release film 11 is sucked and supported along the inner surface of the cavity 19c by degassing through the suction hole provided in the cavity 19c provided in the lower mold 19. At this time, the fixing portion of the process release film 11 may be fixed by sucking through a suction hole provided in the peripheral portion of the lower die 19.

The multilayer release film is drawn to a length approximately corresponding to the depth of the cavity by being sucked and supported along the inner surface of the cavity 19c in a state where the fixing portion located at the peripheral edge portion of the film is fixed. The (initial) depth of the cavity 19c in this step can be appropriately set in accordance with the thickness of the resin-sealed semiconductor device manufactured by the resin sealing process of this embodiment. The (initial) depth of the cavity 19c in this step is usually 1.0 to 10.0mm, but is not limited thereto.

In this step, the multilayer release film 11 preferably has flexibility that is easily supported by suction along the inner surface of the cavity 19c and also has heat resistance that can withstand the heating temperature of the molds 15 and 19. It is preferable that the mold 19 be easily released after the resin sealing, and that the sealing resin 18 be easily released.

In the "6 substrate setting" step, the substrate 16 on which the semiconductor chip (chip) 17 (and optional circuit components) is mounted is attached to the upper die 15 so that the semiconductor chip (chip) 17 faces downward, and the upper die 15 is moved so that the semiconductor chip (chip) 17 is positioned at approximately the center of the cavity 19c in the lower die 19, thereby aligning the positions.

Next, in the "7-step of closing", the upper mold 15 and the lower mold 19 are brought into contact with each other to close the mold while maintaining the space of the initial cavity 19c (while bringing the cavity block 19a of the lower mold 19 into the initial position).

Then, in the "8. Compression" step, the cavity block 19a is raised, and the sealing resin 18 in the cavity 19c is compression molded. Accordingly, the semiconductor chip (chip) 17 (and optional circuit parts) on the substrate 16 are sealed by the sealing resin 18.

The difference between the initial depth of the cavity 19c and the final depth of the cavity 19c after compression molding is preferably 1.0mm or more, more preferably 1.3mm or more, and particularly preferably 1.6mm or more. In the case of resin sealing a semiconductor chip (chip) 17 having a large thickness such as a large-capacity NAND flash memory, the difference between the initial depth of the cavity 19c and the final depth of the cavity 19c after compression molding tends to be large, and even in such a case, the multilayer release film of the present invention can adequately resin seal the semiconductor chip (chip) 17 having a large thickness while effectively suppressing the problem of peeling failure or the like.

The final depth (resin thickness after compression molding) of the cavity 19c is preferably 0.5mm or more, more preferably 0.7mm or more, and particularly preferably 1.0mm or more. By setting the final depth of the cavity 19c to 0.5mm or more, the semiconductor chip (chip) 17 having a large thickness such as a large-capacity NAND flash memory can be sealed with resin appropriately.

In the compression molding, it is preferable to heat the sealing resin 18 to a temperature at which the sealing resin exhibits proper fluidity, and in the case where the sealing resin 18 is a thermosetting resin, it is preferable to heat the sealing resin at a temperature and for a time at which the sealing resin after molding is sufficiently cured. For example, the maximum temperature in the resin sealing process can be set to 110 to 190 ℃, more preferably 120 to 180 ℃.

The molding pressure and curing time at this time are not particularly limited, and may be appropriately set according to the type of the sealing resin 18 and the sealing temperature, but may be appropriately set in a range of, for example, 50 to 300kN, more preferably 70 to 150kN, and 1 to 60 minutes, more preferably 2 to 10 minutes.

The sealing resin 18 may be a liquid resin or a resin that is solid at ordinary temperature, but a sealing material that becomes liquid by heating when sealed with a resin can be suitably used. Specifically, as the sealing resin material, mainly an epoxy resin (thermosetting resin which can be cured by forming a crosslinked network with epoxy groups remaining in a polymer, more preferably a biphenyl type epoxy resin, a bisphenol type epoxy resin, an o-cresol novolac type epoxy resin, or the like) is used, and as the sealing resin other than the epoxy resin, a polyimide type resin (polymer resin having imide bonds in the repeating unit of the main chain, more preferably a bismaleimide type, or the like), a silicone type resin (polymer resin having siloxane bonds in the repeating unit of the main skeleton, more preferably a thermosetting addition type, or the like) or the like is used as usual.

Next, in the "9. Mold opening (release)" step, the upper mold 15 is separated from the lower mold 19, and the molded article (resin-sealed semiconductor chip) is taken out of the mold. In this case, it is more preferable that the molded article be easily peeled off from the multilayer release film 11, and particularly preferable that the multilayer release film 11 on the side surface of the cavity 19c be peeled off without biting into the molded article. Further, it is preferable that the surface of the molded article after peeling has no resin defects or the like and has a good appearance. Such more preferred results become readily achievable with the multilayer release film of the present invention.

(use of multilayer Release film in FPC coating layer attachment Process)

The multilayer release film of the present invention can be used in a step of laminating a circuit substrate having a metal wiring pattern formed thereon and a cover film by heating and pressurizing the circuit substrate and the cover film, and is disposed between the cover film and a heat plate or the like for heating and pressurizing the circuit substrate and the cover film. By using the multilayer release film of the present invention, release failure such as a self-heating plate and bleeding of an adhesive on a cover film can be effectively prevented.

The adhesive on the cover film may be any of a thermoplastic resin and a thermosetting resin, but thermosetting resins are widely used in the technical field, and epoxy-based thermosetting resins are particularly preferred.

The lamination integration step of the circuit substrate for FPC and the coverlay film is the most typical in the above-described manufacturing process, but the multilayer release film of the present invention is not limited thereto, and can be applied to a manufacturing process of a non-flexible printed circuit board or the like.

Examples (example)

The present invention will be described in further detail by way of examples, but the present invention is not limited thereto.

In the following examples, comparative examples and production examples, evaluation of physical properties and characteristics was performed by the following methods.

(contact angle with Water (Water contact angle))

The water contact angle of the surface of the release layer A after the electron beam irradiation was measured by using a contact angle measuring instrument (FACECA-W, manufactured by Kyowa Inter face Science Co., ltd.) in accordance with JIS R3257.

(elongation at break)

The single-layer release film produced in the production example was used, the initial gap between the chucks was set at 50mm, and the film was stretched in the TD direction at 300mm/min at 23℃to measure the elongation at break as the elongation at break point. The measurement direction was set to be the TD direction (width direction at the time of film production).

The evaluation was carried out to evaluate the value of the elongation at break point after irradiation of 100kGy of absorbed dose electron beam at an acceleration voltage of 200kV, and the case of showing more than 20% as compared with the value of the elongation at break point before electron beam irradiation was evaluated as "good", and the case of showing 20% or less as "X".

(Release: semiconductor resin sealing)

Using the multilayer release films fabricated in each example/comparative example, resin sealing of semiconductor chips (chips) was performed in the process shown in fig. 1.

The sealing resin used was an epoxy-based lead frame sealing material (brand name: CEL-9750ZHF 10) manufactured by Hitachi chemical industries Co., ltd.

The details of the process of FIG. 1, "4. Resin+film transfer", "5. Vacuum pumping", and "7 die" and "9. Compression" are shown in FIGS. 2 (a), (b) and (c). In FIG. 2 (a), the depth a of the cavity 29c at the initial stage of mold clamping ₁ 2.4mm, a width of the cavity 29c of 54mm in FIG. 2 (b), a length of 221mm in a direction perpendicular to a paper surface of the cavity 29c in FIG. 2 (b), and a final depth a of the cavity after mold closing and compression in FIG. 2 (c) ₂ Is 0.8mm. The temperature of the molding die (molding temperature) was 175 ℃, the molding pressure was 96kN, and the molding time was 120 seconds.

Then, the upper mold is lifted up in a manner as shown by "9. Mold opening (release)" in fig. 1, and the resin-sealed semiconductor chip (semiconductor package) is released from the release film. Release properties of the release film were evaluated according to the following criteria.

And (3) the following materials: the release film is naturally peeled off simultaneously with the opening of the mold.

And (2) the following steps: the release film does not peel naturally, but easily peels off by hand pulling (when tension is applied).

X: the release film is closely adhered to the resin sealing surface of the semiconductor package and cannot be peeled off by hand. (Release: FPC cover layer attachment)

Using the apparatus having the structure shown in fig. 3, the cover film 76 is disposed on both sides of the circuit substrate 75, and the release film 71a or 72b and the glass cloth 78a or 78b are sequentially stacked on both sides thereof, and the heat plate 77a or 77b is used to heat: 180 ℃, pressure: 10MPa, heating and pressurizing time: a flexible printed board was manufactured by applying heat and pressure for 130 seconds (10 seconds for pre-pressing and 120 seconds for main pressing) and bonding.

1) The circuit substrate 75 was formed of a polyimide film having a thickness of 25 μm, which is a flexible resin substrate, and a polyimide film having a thickness of 22 μm (copper: 12 μm, plating: 10 μm), the line width/space width of the copper wiring portion was 40 μm and 60 μm, respectively.

2) As the cover film 76, a cover film (manufactured by NIKKAN INDUSTRIES corporation, trade name: CISV1225 DB).

The cover film 76 is stamped with a plurality of portions (openings) corresponding to the terminal portions of the circuit substrate 75. The size of the opening of the cover film 76 was 4mm×7mm.

3) When the circuit substrate 75 and the cover film 76 are stacked, the copper wiring of the former and the adhesive layer of the latter are disposed so as to face each other, and when the cover film 76 and the release film 71a are stacked, the polyimide film layer of the former and the release layer of the latter are disposed so as to face each other.

Immediately after the heating and pressing, the release film was peeled off, and the release properties of the release film were evaluated according to the following criteria.

And (2) the following steps: can be easily peeled off from the flexible printed board

X: is attached to a flexible printed board and cannot be easily peeled off (breaking of release layer: semiconductor resin sealing)

The rupturability of the release film at the time of releasing in the above step was evaluated on the basis of the following criteria.

And (2) the following steps: after the release film is released from the semiconductor package after the resin sealing, the film is free from cracking

X: after the release film is released from the semiconductor package after the resin sealing, the film is broken (breaking of release layer: FPC cover layer attachment)

And (2) the following steps: after the release film is released from the FPC by heating and pressurizing, the film is free from cracking

X: after the release film is released from the FPC by heating and pressurizing, the film is broken (mold following property: semiconductor resin sealing)

Mold following properties of the release film at the time of releasing in the above steps were evaluated based on the following criteria.

And (2) the following steps: in the semiconductor package, there is no resin defect (a portion not filled with resin) at all; or at the ends of the semiconductor package, some Xu Shuzhi are missing.

X: at the end of the semiconductor package, there are many resin cuts; or film breakage occurs during forming.

( Follow-up (suppression of adhesive bleeding): FPC cover layer attachment )

The outflow amount of the adhesive on the copper wiring of the FPC after heating and pressing was observed with an optical microscope (VHX-5000, manufactured by Keyence corporation) by using the same combination of the device and the film as the device used in the above-described release property evaluation, and the following properties were evaluated according to the following criteria.

And (2) the following steps: the outflow amount at the opening is less than 25 μm

X: the outflow quantity at the opening exceeds 25 μm

(side biting: semiconductor resin sealing)

The peeling failure due to the side biting of the release film at the time of releasing in the above step was evaluated based on the following criteria.

And (3) the following materials: the semiconductor package has no biting mark and no peeling failure on the side surface.

And (2) the following steps: the semiconductor package has a biting mark on a side surface thereof without peeling failure.

X: the semiconductor package has a biting mark on a side surface thereof, and peeling failure occurs.

(buffer layer oozing: FPC cover layer attaching)

The release films 78a and 78b were evaluated according to the extent to which they were adhered by bleeding of the buffer layer in the release film after heating and pressing in the same combination of the device and the film as the device used in the evaluation of the releasability described above.

And (2) the following steps: the release films 78a and 78b can be easily peeled off, and it is determined that the bleeding of the buffer layer is small.

X: since the release films 78a and 78b cannot be easily peeled off, it is determined that the buffer layer oozes much.

< manufacturing examples 1 to 16: evaluation of monolayer 50 μm thick film (Release layer)

(film-making)

A master batch was prepared from 95wt% of 4-methyl-1-pentene copolymer resin (product name: TPX, brand name: DX818, melting point: 232 ℃ C.) and 5wt% of an additive (radical scavenger) by Sanjing chemical Co., ltd. The types of additives (radical scavenger) used were as shown in the prescriptions and additive columns of table 1, and the details of the additives were as follows.

Hindered Amine Light Stabilizer (HALS) of Tinuvin770

Bis (2, 6-tetramethyl-4-piperidinyl) sebacate (product name: tinuvin770 DF) manufactured by BASF JAPAN Co., ltd

Hindered Amine Light Stabilizer (HALS) (Tinuvin 123)

Bis- (1-octyloxy-2, 6-tetramethyl-4-piperidinyl) sebacate (product name: tinuvin 123) manufactured by BASF JAPAN Co., ltd

Hindered Amine Light Stabilizer (HALS) of (LA-52)

Tetrakis (1, 2, 6-tetramethyl-4-piperidinyl) butane-1,2,3, 4-tetracarboxylic acid ester (product name: ADK STAB LA-52)

(LA-57): hindered Amine Light Stabilizer (HALS)

Tetrakis (2, 6-tetramethyl-4-piperidyl) butane-1,2,3, 4-tetracarboxylic acid ester (product name: ADK STAB LA-57)

Phenolic antioxidant (BHT)

2,6-Di-tert-butyl-4-methylphenol (product name: H-BHT) manufactured by Benzhou chemical industry Co., ltd

Phenolic antioxidant (Irganox 1076)

Octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (product name Irganox 1076) manufactured by BASF JAPAN Co., ltd

Phosphorus antioxidant (Irgafos 168)

Tris (2, 4-di-tert-butylphenyl) phosphite (Tris (2, 4-di-tert. -butyl phenyl) phosphate, manufactured by BASF JAPAN Co., ltd.) (product name Irgafos 168)

Next, the resin composition obtained was melt-extruded at 270℃after blending to obtain the formulation shown in Table 1, and the slit width of the T die was adjusted to obtain a 50 μm thick, non-stretched film.

(Electron Beam irradiation)

The obtained monolayer 50 μm thick film was irradiated with an absorbed dose electron beam of 100kGy at an acceleration voltage of 200kV by an electron beam irradiation apparatus. The evaluation results are shown in table 1.

TABLE 1

The elongation at break of the single-layer resin film (production example 16) containing no radical scavenger (additive) was 553%, but the elongation at break of the film after electron beam irradiation was reduced to 5% (production example 11), and the elongation at break after electron beam irradiation was reduced to less than 1% compared to that before irradiation.

The values of the elongation at break of the single-layer resin films of production examples 1 to 10 containing 0.5 to 2.0 wt% of the radical scavenger (additive) relative to the total amount of the single-layer resin film showed more than 20% compared to the value of the elongation at break before the electron beam irradiation, and maintained good elongation at break.

< examples 1 to 8, comparative examples 1 to 2: evaluation of multilayer film

(film-making)

The resin composition blended in the composition ratio shown in table 1 was used as the resin for the release layer.

As the resin for the core layer, a low-density polyethylene resin (Du Pont-Mitsui Polychemicals Co., ltd., MIRASON F9673P) was used.

40 parts by mass of 4-methyl-1-pentene copolymer resin (product name: TPX, brand name: DX 818) and 60 parts by mass of low-density polyethylene resin (Du Pont-Mitsui Polychemicals, MIRASON F9673P) were blended to prepare a resin composition, and the resin composition was used as a resin for an intermediate layer.

3 extruders (40 mm. Phi. Each) were prepared, and the release layer resin described above was fed to the 1 st extruder and melted at 270 ℃. The resin for the core layer was fed to the 2 nd extruder and melted at a temperature of 210 ℃. The resin for the core layer was fed to a 3 rd extruder and melted at 270 ℃.

The melted resin was led to a dispensing adapter (adapter) and the 5-layer film consisting of the layers of release layer/intermediate layer/core layer/intermediate layer/release layer was taken out through a T-die having a temperature set to 270 ℃.

The total thickness of the obtained 5-layer co-extruded film was 50. Mu.m, the total thickness of the semiconductor resin layer was 120. Mu.m, and the layer composition was as shown in tables 2 and 3.

(Electron Beam irradiation)

The resulting multilayer film was irradiated with electron rays at an acceleration voltage of 200kV and at the absorbed dose shown in tables 2 and 3. The evaluation results are shown in tables 2 and 3.

TABLE 2

Table 2 evaluation results of multilayer film for semiconductor resin sealing

TABLE 3

Table 3 evaluation results of multilayer film for FPC coating

The multilayer films for sealing semiconductor resins of examples 1 to 4, in which the resin composition containing the radical scavenger (additive) was used in the release layer, gave good results in all the evaluation items of breakage of the release layer, biting of the side surface, mold following property, and release property, but in comparative example 1, in which the resin composition containing no radical scavenger (additive) was used in the release layer, breakage of the release layer could not be suppressed.

Similarly, the multilayer films for attaching FPC cover layers of examples 5 to 8, in which the resin composition containing the radical scavenger (additive) was used in the release layer, gave good results in all the evaluation items of the breakage of the release layer, the bleeding out of the buffer layer, the following property, and the release property, but the breakage of the release layer could not be suppressed in comparative example 2, in which the resin composition containing no radical scavenger (additive) was used in the release layer.

[ Industrial applicability ]

The multilayer release film of the present invention can achieve excellent physical properties such as fracture resistance, followability, release properties, prevention of biting of a side surface, and suppression of bleeding of a buffer layer at a high level which cannot be achieved in the conventional art, and can have a practically high value, and is highly useful in various fields of industries including semiconductor process industry, optical element manufacturing industry, electronic component industry, electric and electronic industry, mechanical industry, and automobile industry.

Description of the reference numerals

11,21 multilayer release film

12. Cutter knife

13 X-Y table

14,24 frame

15,25 upper mould

16,26 substrates

17,27 semiconductor chip

18. Sealing resin

19,29 lower die

19a,29a cavity block

19b,29b holders

19c,29c mold cavities

a ₁ Initial depth of mold cavity

a ₂ Final depth of mold cavity

75. Circuit base material

76. Cover layer film

71a,71b multilayer release film

77a,77b hot plate

78a,78b glass cloths.

Claims

1. A multilayer release film is formed by crosslinking a resin layer B by electron beam irradiation of a multilayer film comprising a release layer A containing a non-crosslinkable resin and a radical scavenger, and a resin layer B containing a vinyl polymer; wherein,

the contact angle of the release layer A after electron beam irradiation for water is 90-130 degrees; and is also provided with

The non-crosslinking resin contained in the release layer A is poly (4-methyl-1-pentene) and/or a copolymer thereof.

2. The multilayer release film according to claim 1, wherein the release layer a has a melting point of 200 ℃ or higher as determined by a differential scanning calorimeter.

3. The multilayer release film according to claim 1 or 2, wherein the total content of radical scavenger is 0.5 to 2.0 wt% relative to the total weight of release layer a.

4. The multilayer release film according to claim 1 or 2, wherein the radical scavenger is at least one selected from the group consisting of a hindered amine light stabilizer, a phenolic antioxidant, a phosphorus antioxidant, and a polymerization inhibitor.

5. The multilayer release film according to claim 1 or 2, wherein the radical scavenger contained in the release layer a contains a hindered amine light stabilizer.

6. The multilayer release film according to claim 1 or 2, wherein the radical scavenger contained in the release layer a contains a phenolic antioxidant.

7. The multilayer release film according to claim 1 or 2, wherein the radical scavenger contained in the release layer a contains a hindered amine light stabilizer and a phosphorus-based antioxidant.

8. The multilayer release film according to claim 1 or 2, having the release layer a on both surface layers and the resin layer B on the core layer.

9. The multilayer release film according to claim 1 or 2, for use in a printed circuit board manufacturing process or a resin sealing process of a semiconductor.