WO2007029979A1 - Release film for pcb lamination process - Google Patents

Release film for pcb lamination process Download PDF

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Publication number
WO2007029979A1
WO2007029979A1 PCT/KR2006/003567 KR2006003567W WO2007029979A1 WO 2007029979 A1 WO2007029979 A1 WO 2007029979A1 KR 2006003567 W KR2006003567 W KR 2006003567W WO 2007029979 A1 WO2007029979 A1 WO 2007029979A1
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WO
WIPO (PCT)
Prior art keywords
layer
film
resin
release film
polycarbonate
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Application number
PCT/KR2006/003567
Other languages
French (fr)
Inventor
Seong-Min Kim
Original Assignee
Seong-Min Kim
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Publication of WO2007029979A1 publication Critical patent/WO2007029979A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/28—Applying non-metallic protective coatings
    • H05K3/281—Applying non-metallic protective coatings by means of a preformed insulating foil
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
    • B29C33/68—Release sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B25/00—Layered products comprising a layer of natural or synthetic rubber
    • B32B25/04—Layered products comprising a layer of natural or synthetic rubber comprising rubber as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B25/08—Layered products comprising a layer of natural or synthetic rubber comprising rubber as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B25/00—Layered products comprising a layer of natural or synthetic rubber
    • B32B25/18—Layered products comprising a layer of natural or synthetic rubber comprising butyl or halobutyl rubber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B32B27/365—Layered products comprising a layer of synthetic resin comprising polyesters comprising polycarbonates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
    • B32B37/26—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer which influences the bonding during the lamination process, e.g. release layers or pressure equalising layers
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/10—Polymers of propylene
    • B29K2023/12—PP, i.e. polypropylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2069/00—Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
    • B32B37/26—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer which influences the bonding during the lamination process, e.g. release layers or pressure equalising layers
    • B32B2037/268—Release layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/306—Resistant to heat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/518—Oriented bi-axially
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/538—Roughness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/546—Flexural strength; Flexion stiffness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/748—Releasability
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/08—PCBs, i.e. printed circuit boards

Definitions

  • the present invention relates to a release film for PCB lamination processes, and more particularly to a release film which is used to prevent the adhesion of a cover- layer film to a press during a process of laminating a cover layer, such as a polyimide film, on the outer surface of a printed circuit board (PCB).
  • a cover- layer film such as a polyimide film
  • the PCB (printed circuit board) is a key component known as one of the four most important electronic components, also including a semiconductor, a display and a secondary battery, and is widely used in various electronic products, including TVs, computers, mobile phones, displays, communication network devices and semiconductor modules.
  • This cover layer is generally made of a polyimide film having excellent chemical resistance and thermal resistance.
  • FIG. 1 is a schematic diagram showing one example of a PCB lamination process.
  • a polyimide film 120 as a cover layer is laminated on both sides of a PCB 100 using, for example, a thermosetting adhesive (e.g., epoxy resin) or a thermosetting adhesive (e.g., acrylic resin) 110.
  • a thermosetting adhesive e.g., epoxy resin
  • a thermosetting adhesive e.g., acrylic resin
  • the polyimide film 120 is placed on both sides of the PCB 100 with the adhesive 110 interposed therebetween, and in this state, pressing work is carried out to adhere the cover layer closely to the PCB 100.
  • each of the surfaces of the PCB 100 has connectors for electrical connection with external elements, these connector portions are not covered with the polyimide film 120.
  • the cover layer is formed to have open cells 102.
  • the PCB 100 together with upper and lower press units has the following layer structure.
  • thermoplastic adhesive e.g., acrylic resin
  • thermosetting adhesive e.g., epoxy resin
  • the respective press units are provided, which have, as shown in FIG. 1, a structure in which a paper sheet 310 and a flexible PVC sheet 320 are sequentially deposited inside a steel plate 300. Also, a release film 200 is positioned between each of the press units and the polyimide film 120 adhered to the PCB 100.
  • the steel plate 300 functions to transfer pressure while conducting heat for lamination, and the paper sheet 310 is used to prevent adhesion between the steel plate 300 and the PVC sheet 320 and ensure that the pressure is uniformly applied.
  • the PVC sheet 320 is the most important element functioning as a buffer for adhering the cover layer closely to the PCB 100, and may also be substituted with a PE material having low thermal resistance and a buffer property similar to PVC.
  • the release film 200 functions to prevent adhesion between the PVC sheet (or PE sheet) 320 and the polyimide film 120 as the cover layer, and enable the PVC sheet and the cover layer to be smoothly separated from each other after the press work is completed.
  • examples of the release film which are currently used in the art, include a polymethylpentene film, a kind of cyclic olefin copolymer, a film having re- leasability provided by coating silicon on an oriented polyethylene terephthalate film, a Teflon film, a polypropylene film, etc.
  • TPX Mitsui Chemicals Inc.
  • Teflon film is expensive, and thus is only used by some manufacturers, and the polypropylene film has reduced heat resistance, and thus is used only in low- temperature processes conducted below 150 0 C.
  • the present invention has been made in view of the above-described problems occurring in the present invention, and it is an object of the present invention to provide a release film for PCB lamination processes, which is used to prevent the adhesion of a cover-layer film to a press during a process of laminating a cover layer on the outer surface of a PCB, and has excellent releasability and pressing properties,
  • the releasing film comprising a base layer consisting of a film made of any one selected from the group consisting of polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and
  • the present invention provides a release film for PCB lamination processes, which is obtained by laminating a layer B, consisting of polypropylene (PP) resin, on one side of a layer A, consisting of a film made of any one selected from the group consisting of polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET).
  • the A layer is a non-oriented film.
  • the present invention provides a release film for PCB lamination processes, which is obtained by laminating a layer B, consisting of polypropylene resin (PP), on one side of a layer A, consisting of a non-oriented film made of polyethylene terephthalate (PET).
  • a layer B consisting of polypropylene resin (PP)
  • a layer A consisting of a non-oriented film made of polyethylene terephthalate (PET).
  • the inventive release film is obtained by laminating another layer B, consisting of polypropylene (PP) resin, on the other side of said layer A.
  • PP polypropylene
  • the inventive release film is obtained by laminating a layer C, consisting of polyethylene (PE) resin, on the other side of said layer A.
  • PE polyethylene
  • said layer A of the inventive release film contains a polyester elastomer based on polybutylene terephthalate.
  • said layer B of the inventive release film contains at least one selected from among ethylene and 1-butene.
  • said layer A of the inventive release film has a thickness of 10-100 D.
  • said layer B of the inventive release film has a thickness of 2- 15 D.
  • said layer C of the inventive release film has a thickness of 100-300 D.
  • the present invention provides an excellent release film, which resists pressing conditions of high temperature and high pressure and, at the same time, has excellent releasability from a polyimide film as a cover layer and does not substantially transfer material to the PCB or the cover layer.
  • the inventive release film provides an excellent effect of reducing the failure rate of a lamination process, because it does not react with epoxy resin or acrylic resin.
  • the inventive release film has properties similar or superior to an expensive PMP material that has been used in the prior art.
  • FIG. 1 is a schematic diagram showing one example of a PCB lamination process.
  • FIG. 2 is a cross-sectional view of a release film according to one embodiment of the present invention.
  • FIG. 3 is a cross-sectional view of a release film according to another embodiment of the present invention.
  • FIG. 4 is a cross-sectional view of a release film according to still another embodiment of the present invention.
  • FIG. 2 is a cross-sectional view of a release film according to one embodiment of the present invention.
  • the conventional work conditions of PCB lamination processes are as follows: work temperature: 130-180 0 C; pressure: 40-90 kgf/cm ; and pressing time: about 60 minutes.
  • the release film for PCB lamination processes must be able to resist the above work conditions and, at the same time, must have excellent releasability from a polyimide film as a cover layer and have high purity such that no material is transferred from the release film to the PCB or the cover layer.
  • layer B consisting of polypropylene (PP) resin
  • layer A consisting of either a film made of any one selected from the group consisting of polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), or a non-oriented film made of polyethylene terephthalate (PET).
  • PC polycarbonate
  • PBT polybutylene terephthalate
  • PBT polyethylene terephthalate
  • PET polyethylene terephthalate
  • Said polycarbonate resin has excellent heat resistance, and thus does not melt at the above-described work temperature, and provides excellent elongation (flexibility), so that it enables the pressure of the press to be applied uniformly over the entire surface of the polyimide film acting as the cover layer. It is preferable for the present invention to use polycarbonate resin having a glass transition temperature (Tg) of 130-180 0 C, and more preferably about 150 0 C.
  • Tg glass transition temperature
  • Materials usable as the polycarbonate resin in the present invention include straight- chain polymers, branched-chain polymers, high-heat-resistant polymers containing phthalate for increasing the heat resistance thereof, and silicon copolymers having increased impact resistance, and preferably have a viscosity-average molecular weight (Mv) of 15000-30000 corresponding to a melt flow index of 1-50, as measured under conditions of 300 0 C and 1.2 kg.
  • Mv viscosity-average molecular weight
  • the molecular weight must be within a suitable range.
  • polycarbonate resin can be maintained at a glass transition temperature of about 150 0 C without the need to conduct orientation, and thus shows good pressability compared to the oriented film, even when it is used in the fabrication of a PCB having a complicated structure. Also, because polycarbonate resin is a completely amorphous resin, it is not crystallized even under high-temperature heat treatment conditions, and thus it does not shrink, thus exhibiting good properties for use as a release film.
  • Materials usable as the polybutylene terephthalate (PBT) resin in the present invention include straight-chain polymers, branched-chain polymers, and high- heat-resistant polymers containing a naphthalenic compound for increasing the heat resistance thereof, and preferably have an intrinsic viscosity (LV) ranging from 0.5 dl/ g to 1.5 dl/g.
  • LV intrinsic viscosity
  • polybutylene terephthalate having a viscosity lower than 0.5 dl/g, it has an excessively high flow index, which makes the film formation process difficult, and if polybutylene terephthalate, having a viscosity higher than 1.5 dl/g, is used, it shows decreased flow index, which increases the roughness of a film surface in a film forming process and reduces work efficiency.
  • Polybutylene terephthalate resin after being extruded into a film, shows excellent elongation (flexibility) and toughness whether at high temperature or room temperature, so that it can show excellent pressability upon the fabrication of a complicated and fine circuit board.
  • polybutylene terephthalate (PBT) shows a melting behavior in which it is well miscible with polycarbonate (PC) in the full temperature range.
  • PC polycarbonate
  • the polycarbonate in order to prevent chemical damage to polycarbonate caused by an acrylic or epoxy resin adhesive component applied to the inside of the cover layer and by the remaining solvent during a PCB lamination process, can be used in a mixture with polybutylene terephthalate to improve the chemical resistance of the release film.
  • PET resin materials usable as polyethylene terephthalate (PET) resin in the present invention include straight-chain polymers, branched-chain polymers, and high-heat-resistant polymers containing a naphthalenic compound for increasing the heat resistance thereof, and preferably have an intrinsic viscosity (LV.) ranging from 0.5 dl/g to 1.0 dl/ g.
  • PET generally has a glass transition temperature of about 75 0 C, it can be imparted with a glass transition temperature of 75-125 0 C by using a naphthalenic compound, and thus can be used in various applications depending on its heat resistance.
  • polyethylene terephthalate having an intrinsic viscosity lower than 0.5 dl/g it shows low melt tension and an excessively high melt index, making the film forming process difficult, and if polyethylene terephthalate having a viscosity greater than 1.0 dl/g is used, it shows a low flow index, also making the film forming process difficult.
  • PC polycarbonate
  • PBT polybutylene terephthalate
  • said layer A is preferably structured such that it contains a polyester elastomer based on polybutylene terephthalate.
  • the polyester elastomer serves to improve pressability so as to increase the adhesion of the polyimide film to the fine portions of PCB, even under conditions of process temperatures lower than existing products.
  • the polyester elastomer it is preferable for the present invention to use a polyester elastomer based on polybutylene terephthalate, having a melting point of more than 150 0 C and a Shore hardness of more than 30.
  • the polyester elastomer resin based on polybutylene terephthalate is prepared through a melt polycondensation process, as in the case of preparing polybutylene terephthalate or polyethylene terephthalate.
  • PTMEG polyte- tramethylene etherglycol
  • polytetrame thy lene etherglycol is used in an amount of less than 5 wt%, the resulting polymer will have insufficient elastomeric properties due to the low elastomer content, and if polytetramethylene etherglycol is used in an amount more than 60 wt%, it will make polymerization difficult and result in a reduction in the melting point, and thus will be unsuitable for the object of the present invention.
  • the polytetramethylene etherglycol (PTMEG) which is used as a comonomer in the present invention, may have various molecular weights, and generally a number- average molecular weight (Mn) of 1000-3000.
  • the melting point of the polyester elastomer changes depending on the molecular weight of the material used for copolymerization, even when the material is used in the same amount. Specifically, if a material having a low molecular weight is used, the melting point of the polyester elastomer will be decreased, and if a high- molecular- weight material is used, the melting point of the polyester elastomer will be increased. However, a material having a melting point of more than 150 0 C and a Shore hardness (D scale) of more than 30 can be used in the present invention, regardless of the molecular weight and content thereof.
  • the layer A preferably contains the polyester elastomer in an amount of 0-50 parts by weight based on 30-100 parts by weight of one or more resins selected from among polycarbonate, polybutylene terephthalate, and polyethylene terephthalate.
  • the polyester elastomer is preferably contained in the layer A in an amount of 3-20 parts by weight, because an increase in the content thereof leads to an increase in die swell during extrusion, and a decrease in transparency.
  • the layer A preferably contains an antioxidant in an amount of 0-5 parts by weight based on 30-100 parts by weight of either a film consisting of any one selected from among polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), or a non-oriented film consisting of polyethylene terephthalate (PET).
  • PC polycarbonate
  • PBT polybutylene terephthalate
  • PBT polybutylene terephthalate
  • PBT polyethylene terephthalate
  • PET polyethylene terephthalate
  • the antioxidant is used to prevent resin pyrolysis, oxidation, crosslinking, discoloration and the like, which can occur during high-temperature processes such as a compounding extrusion or film extrusion process.
  • a conventional phenolic antioxidant as a primary antioxidant and to use a conventional phosphite or phosphonite antioxidant as a secondary antioxidant.
  • the antioxidant which is used in the present invention, is generally an antioxidant used for polycarbonate and polyester elastomers, and any antioxidant can be used in the present invention as long as it has excellent high heat resistance and excellent acid resistance, base resistance, oil resistance and the like.
  • the present invention does not need to be limited to the above-exemplified antioxidants.
  • the inventive release film can be prepared in a non-oriented, uniaxially oriented or biaxially oriented state, it is particularly preferable to prepare the release film in a non-oriented state in view of pressability.
  • the orientation of the release film should be easy to perform in order to increase the adhesion thereof to fine portions during a press adhesion process, but the oriented film shows a reduced orientation property during the adhesion process, because it is already highly oriented.
  • a non-oriented film is not yet oriented, it can be easily oriented during the pressing operation to increase the adhesion thereof to fine portions.
  • the layer B consists of polypropylene (PP) resin.
  • Polyolefin resins are generally known to have excellent chemical resistance, and particularly, polyolefin resins having excellent heat resistance, include cyclic olefin copolymers (COC), polymethylpentene (PMP) and the like.
  • COC cyclic olefin copolymers
  • PMP polymethylpentene
  • poly- methylpentene is disadvantageously expensive, although it has excellent properties.
  • polypropylene (PP) resin having excellent heat resistance and general usefulness, is used.
  • the polypropylene resin (PP) resin which is used in the present invention, is structured such that it has a melting point of about 165 0 C. Except for some cases where an adhesive for application to the polyimide film (i.e., cover layer) must be used at temperatures higher than 170 0 C, the polypropylene resin shows good pressability at a temperature of about 165 0 C. Thus, it enables satisfactory pressability to be realized, when a pressing temperature of 150-160 0 C is applied.
  • polypropylene resin which can be used in the present invention, include polypropylene homopolymers and polypropylene copolymers.
  • the polypropylene copolymers can be in the form of random copolymers, block copolymers or graft copolymers.
  • an adhesive can flow out through the open cells 102 (FIG. 1) of the polyimide film 120 (FIG. 1) due to the pressure of the press, so that the release film can adhere to the polyimide film.
  • the layer B consisting of polypropylene (PP) resin, is laminated on one side of the layer A, and the resulting film is deposited and pressed during the lamination process, such that the layer B faces the polyimide film.
  • PP polypropylene
  • the layer B is preferably structured such that it contains at least one of ethylene and 1-butene.
  • the layer B preferably contains at least one of ethylene and 1-butene in an amount of 0-7 parts by weight based on 93-100 parts by weight of polypropylene.
  • the layer A preferably has a thickness of 10-100 D, and more preferably
  • the thickness of the layer A is smaller than 10 D, the pressability of the layer B can be reduced, and if it is larger than 100 D, the layer A can be damaged due to the difference in thermal expansion coefficient from PCB upon cooling after the pressing operation.
  • the layer B preferably a thickness of 2-15 D, and more preferably 5-10 D. If the layer B is thinner than 2 D, it will be difficult to form a film, and if it is thicker than 15 D, it will be excessively hard, resulting in a reduction in pressability.
  • the layer A and layer B can be laminated to each other according to a conventional known method, such as dry lamination, extrusion lamination, or coextrusion, to form one film.
  • FIG. 3 is a cross-sectional view of a release film according to another embodiment of the present invention.
  • the inventive release film for PCB lamination processes is obtained by laminating another layer B consisting of polypropylene (PP) resin on the other side of the layer A having the layer B laminated on one side thereof.
  • PP polypropylene
  • the layer B is laminated on both surfaces of the layer A made of a non- oriented film consisting of any one selected from among polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), or a non- oriented film consisting of a polyethylene terephthalate (PET).
  • PC polycarbonate
  • PBT polybutylene terephthalate
  • PBT polyethylene terephthalate
  • PET polyethylene terephthalate
  • each of the layer A and layer B can be the same as described above.
  • FIG. 4 is a cross-sectional view of a release film according to still another embodiment of the present invention.
  • the inventive release film for PCB lamination processes is obtained by laminating layer C, consisting of polyethylene (PE) resin, on the other side of the layer A having the layer B laminated on one side thereof.
  • layer C consisting of polyethylene (PE) resin
  • the layer C consisting of polyethylene (PE) resin can also function as the PVC sheet (or PE sheet) provided on the press unit of FIG. 1, i.e., a buffer layer.
  • PE polyethylene
  • the press unit is provided above and below the
  • the PCB 100 during the lamination process, and has a structure in which the paper sheet 310 and the flexible PVC sheet 320 are sequentially formed inside the steel plate 300. Also, the release film 200 is located between each of the press units and the polyimide film 210 adhered to the PCB 100.
  • the press unit does not need to be provided with a separate buffer layer, such as the PVC sheet 320.
  • the release film having the layer C formed thereon can be laminated alone between the paper sheet 310 and the polyimide film 120 without using the PVC sheet 320, and the resulting structure can be subjected to a pressing operation.
  • the layer C is not brought into direct contact with the polyimide film 120 and the heat resistance thereof does not need to be considered, it is formed by laminating polyethylene (PE) resin, which is used as a conventional buffer.
  • the polyethylene (PE) resin has a characteristic of being easily laminated to polycarbonate resin (PC).
  • the film or sheet, used as the conventional buffer has a thickness of more than 100
  • buffer polyethylene low-density polyethylene or linear low-density polyethylene having a density of less than 0.93 g/cm is generally used, and the densities or fundamental properties of these resins will vary depending on the catalyst and the method used for the preparation thereof.
  • polyethylene has a melting point of 100-120 0 C, which is lower than the temperature of the pressing process, and thus it can be melted to impart pressability thereto.
  • the layer C preferably has a thickness of about 100-300 D, and more preferably 120-200 D in view of economic efficiency.
  • Polycarbonate films were prepared in the following manner. First, the following components were mixed well with each other: 68 parts by weight of TRIREX 3026 (branched copolymer, commercially available from Samyang Corporation, Korea; density: 1.2 g/cm ; MI: 0.81 g/10 min (300 0 C, 1.2 kg); glass transition temperature: 148 0 C); 23 parts by weight of TRIREX 3020 (Samyang Corporation, Korea; density: 1.2 g/cm 3 ; MI: 10 g/10 min (300 0 C, 1.2 kg); Vicat softening temperature: 144 0 C); 9 parts by weight of TRIEL 5400 (polybutylene terephthalate-based polyester elastomer commercially available from Samyang Corp., Korea; density: 1.15 g/cm ; MI: 14 g/10 min (230 0 C, 2.16 kg); melting point: 205 0 C), 0.1 parts by weight of Songnox 1010 (antioxidant commercially available from Songwon
  • the mixture was extruded in a twin extruder (47 m/m, L/D 48) at a temperature of 250-280 0 C.
  • the extruded material was formed into non-oriented films having 30, 35 and 40 D, respectively, using a T-die casting (110 m/m, L/D 32) method at an extruder temperature of 270-300 0 C.
  • a polybutylene terephthalate film was prepared in the following manner. First, the following materials were mixed well with each other: 100 parts by weight of TRIBIT 1700 (commercially available from Samyang Corp., Korea; density: 1.31 g/cm ; MI: 20 g/10 min (260 0 C, 2.16 kg); glass transition temperature: 148 0 C); 0.1 parts by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 parts by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals).
  • TRIBIT 1700 commercially available from Samyang Corp., Korea
  • density 1.31 g/cm
  • MI 20 g/10 min (260 0 C, 2.16 kg)
  • glass transition temperature 148 0 C
  • Songnox 1010 antioxidant commercially available from Songwon Industrial Co., Ltd., Korea
  • Irganox 168 antioxidant commercially available from Ciba Specialty Chemicals
  • the mixture was extruded in a twin extruder (47 m/m, L/D 48) at a temperature of 220-250 0 C).
  • the extruded material was formed into a non-oriented film having a thickness of 35 D, using a T-die casting method 110 m/m, L/D 32) at an extruder temperature of 230-260 0 C.
  • a polybutylene terephthalate film was prepared in the following manner. First, the following materials were mixed well with each other: 95 parts by weight of TRIBIT 1700 (commercially available from Samyang Corp., Korea; density: 1.31 g/cm ; MI: 20 g/10 min (260 0 C, 2.16 kg); glass transition temperature: 148 0 C); 5 parts by weight of TRIEL 5400 (commercially available from Samyang Corp., Korea; density: 1.25 g/ cm 3 ; MI: 14 g/10 min (235 0 C, 2.16 kg); glass transition temperature: -20 0 C); 0.1 parts by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 parts by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals).
  • TRIBIT 1700 commercially available from Samyang Corp., Korea; density: 1.31 g/cm ; MI: 20 g/10 min (260 0
  • the mixture was extruded in a twin extruder (47 m/m, L/D 48) at a temperature of 220-250 0 C.
  • the extruded material was formed into a non-oriented film having a thickness of 35 D, using a T-die casting (110 m/m, L/D 32) method at an extruder temperature of 230-260 0 C.
  • a film consisting of a mixture of polycarbonate and polybutylene terephthalate was prepared in the following manner. First, the following materials were mixed well with each other: 65 parts by weight of TRIREX 3026 (Samyang Corp., Korea); 30 parts by weight of TRIBIT 1700 (Samyang Corp., Korea); 5 parts by weight of TRIEL (Samyang Corp., Korea); 0.1 part by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 part by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals).
  • the mixture was extruded in a twin extruder (47 m/m, L/D 48) at a temperature of 240-290 0 C.
  • the extruded material was formed into a non-oriented film having a thickness of 35 D using a T-die casting (110 m/m, L/D 32) method at an extruder temperature of 250-300 0 C.
  • a film consisting of a mixture of polycarbonate and polyethylene terephthalate was prepared in the following manner. First, the following components were mixed well with each other: 50 parts by weight of TRIREX 3026 (Samyang Corp., Korea); 20 parts by weight of TRIREX 3020 (Samyang Corp., Korea); 15 parts by weight of polyethylene terephthalate (commercially available from Huvis; intrinsic viscosity: 0.65 dl/g); 5 parts by weight of TRIEL (Samyang Corp., Korea); 0.1 part by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 part by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals).
  • the mixture was extruded in a twin extruder (47 m/ m, L/D 48) at a temperature of 240-290 0 C.
  • the extruded material was formed into a non-oriented film having a thickness of 35 D using a T-die casting (110 m/m, L/D 32) method at an extruder temperature of 250-300 0 C.
  • Polypropylene films were prepared by extruding 5014 HPT (commercially available from Korea Petrochemical Ind. Co., Ltd.; density: 0.9 g/cm 3 ; MI: 2.5 g/10 min (230 0 C, 2.16 kg); melting point: 165 0 C) at an extruder temperature of 190-250 0 C at Samyoung Chemical Co., Ltd., Korea, thus obtaining biaxially oriented films having thickness of 5, 8 and 12 D, respectively. Also, a 20-D thick polypropylene film was prepared by extruding 5014L (commercially available from Korea Petrochemical Ind.
  • a 130-D thick polyethylene film was prepared by extruding 5304 (commercially available from Hanwha Petrochemical Corp., Korea; density: 0.923 g/cm ; MI: 0.3 g/ 10 min (190 0 C, 2.16 kg); melting point: 112 0 C) at an extruder temperature of 180-230 0 C using an upward inflation process.
  • Example 1 the 5-D thick polypropylene film was laminated on one side of the 40-D thick polycarbonate film.
  • the 8-D thick polypropylene film was laminated on both sides of the
  • Example 4 the 20-D thick polypropylene film was laminated on both sides of the
  • Example 5 the 12-D thick polypropylene film was laminated on one side of the
  • Example 6 the 8-D thick polypropylene film was laminated on both sides of the
  • Example 8 the 8-D polypropylene film was laminated on both sides of the 35-D thick mixed film of polycarbonate and polybutylene terephthalate.
  • Example 9 the 8-D polypropylene film was laminated on both sides of the 35-D thick mixed film of polycarbonate and polyethylene terephthalate.
  • OPULENT TPX commercially available from Mitsui
  • Resin flow is measured as the length of an adhesive that flows out through the open cell of a cover layer (polyimide film) during a pressing operation. Increased resin flow value can show reduced pressability and has an increased possibility of causing plating failures in a process of plating PCB circuits.
  • the following operation conditions were used based on a circuit line width of 100 D: 160 0 C, 50 kgf/cm , 60 min.
  • Platability indicates the excellence of a plating process, and transferability from the release film.
  • a 25-mm wide adhesive tape (610, 3M Company) was adhered closely with a force of 2 kg to make a test sample.
  • the test sample was applied with a pressure of 20 g/cm in an oven at 70 0 C for 10 hours, and then left to stand at room temperature for about 15 minutes. Then, the tape was separated manually and the surface thereof was observed with a microscope (OLYMPUS SZ61, x80) to determine whether the gold plate layer had peeled. If the plate layer was observed to have any peeled portion, it was evaluated as "poor".
  • the "disassembly operation” refers to a process of disassembling elements manually from each other after sufficient cooling following a pressing process at high temperature and high temperature. Smaller peel strength between the cover layer and the release film can show better releasability.
  • the release films prepared according to Examples 1-9 of the present invention had excellent resin flow properties. Particularly, these release films showed resin flow properties similar to or slightly better than the PMP material which has been used in the prior art.
  • release films prepared according to Examples 1-9 of the present invention were similar or superior to Comparative Examples 1-3 with respect to delamination, platability and releasability.

Abstract

Disclosed herein is a release film for PCB lamination processes, which is obtained by laminating a layer B, consisting of polypropylene (PP) resin, on one side of a layer A, consisting of either a film made of any one selected from the group consisting of polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), or a film made of polyethylene terephthalate (PET). The disclosed release film resists pressing process conditions of high temperature and high pressure and, at the same time, has excellent releasability from a polyimide film as a cover layer, and does not substantially transfer a material to PCB or the cover layer.

Description

Description
RELEASE FILM FOR PCB LAMINATION PROCESS
Technical Field
[1] The present invention relates to a release film for PCB lamination processes, and more particularly to a release film which is used to prevent the adhesion of a cover- layer film to a press during a process of laminating a cover layer, such as a polyimide film, on the outer surface of a printed circuit board (PCB). Background Art
[2] The PCB (printed circuit board) is a key component known as one of the four most important electronic components, also including a semiconductor, a display and a secondary battery, and is widely used in various electronic products, including TVs, computers, mobile phones, displays, communication network devices and semiconductor modules.
[3] The outer surface of such PCBs, particularly FPCBs (flexible printed circuit boards), which have recently become widely used, is generally laminated with a cover layer to protect an internal substrate. This cover layer is generally made of a polyimide film having excellent chemical resistance and thermal resistance.
[4] FIG. 1 is a schematic diagram showing one example of a PCB lamination process.
[5] As shown in FIG. 1, a polyimide film 120 as a cover layer is laminated on both sides of a PCB 100 using, for example, a thermosetting adhesive (e.g., epoxy resin) or a thermosetting adhesive (e.g., acrylic resin) 110. For this purpose, the polyimide film 120 is placed on both sides of the PCB 100 with the adhesive 110 interposed therebetween, and in this state, pressing work is carried out to adhere the cover layer closely to the PCB 100.
[6] Because each of the surfaces of the PCB 100 has connectors for electrical connection with external elements, these connector portions are not covered with the polyimide film 120. Thus, the cover layer is formed to have open cells 102.
[7] After the processes of forming the printed circuit board and laminating the cover layer thereon, the PCB is cut into final product units. For this reason, while the cover- layer lamination process is carried out, the plurality of open cells is regularly arranged on one PCB.
[8] Meanwhile, as shown in FIG. 1, during the lamination process, the PCB 100 together with upper and lower press units has the following layer structure.
[9] The PCB 100 is placed between the upper and lower press units, and the polyimide film 120 is adhered on both the upper and lower sides of the PCB 100 with the thermoplastic adhesive (e.g., acrylic resin) or thermosetting adhesive (e.g., epoxy resin) 110 interposed therebetween.
[10] Above and below this PCB 100, the respective press units are provided, which have, as shown in FIG. 1, a structure in which a paper sheet 310 and a flexible PVC sheet 320 are sequentially deposited inside a steel plate 300. Also, a release film 200 is positioned between each of the press units and the polyimide film 120 adhered to the PCB 100.
[11] The steel plate 300 functions to transfer pressure while conducting heat for lamination, and the paper sheet 310 is used to prevent adhesion between the steel plate 300 and the PVC sheet 320 and ensure that the pressure is uniformly applied.
[12] The PVC sheet 320 is the most important element functioning as a buffer for adhering the cover layer closely to the PCB 100, and may also be substituted with a PE material having low thermal resistance and a buffer property similar to PVC.
[13] The release film 200 functions to prevent adhesion between the PVC sheet (or PE sheet) 320 and the polyimide film 120 as the cover layer, and enable the PVC sheet and the cover layer to be smoothly separated from each other after the press work is completed.
[14] Considering this layer structure to be one unit, 20-120 units are generally stacked on each other in view of work efficiency and subjected to a pressing process.
[15] Meanwhile, examples of the release film, which are currently used in the art, include a polymethylpentene film, a kind of cyclic olefin copolymer, a film having re- leasability provided by coating silicon on an oriented polyethylene terephthalate film, a Teflon film, a polypropylene film, etc.
[16] Among them, the polymethylpentene film (PMP; also known by the trade name
"TPX" of Mitsui Chemicals Inc.) is used for high-temperature pressing, because it has excellent release ability and heat resistance and does not substantially transfer material transfer to the polyimide film upon pressing. However, it has a problem in that it has limited use, because it is expensive and supplied in limited amounts.
[17] In the case of the film formed by coating silicon on the oriented polyethylene terephthalate (PET) film, the silicon coating is carried out using a thermosetting process. For this reason, there is a problem in that, when a complete reaction is not achieved during the thermosetting process, unreacted chemicals will be transferred to the polyimide film during pressing so as to cause failures in a plating process.
[18] The Teflon film is expensive, and thus is only used by some manufacturers, and the polypropylene film has reduced heat resistance, and thus is used only in low- temperature processes conducted below 150 0C.
[19] Due to these problems, there is an urgent need to develop a release film for PCB processes, which is relatively inexpensive and, at the same time, is excellent with respect to releasability and pressability, that is, has good heat resistance. Disclosure of Invention
Technical Problem
[20] The present invention has been made in view of the above-described problems occurring in the present invention, and it is an object of the present invention to provide a release film for PCB lamination processes, which is used to prevent the adhesion of a cover-layer film to a press during a process of laminating a cover layer on the outer surface of a PCB, and has excellent releasability and pressing properties, the releasing film comprising a base layer consisting of a film made of any one selected from the group consisting of polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET). Technical Solution
[21] To achieve the above object, the present invention provides a release film for PCB lamination processes, which is obtained by laminating a layer B, consisting of polypropylene (PP) resin, on one side of a layer A, consisting of a film made of any one selected from the group consisting of polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET).
[22] Preferably, the A layer is a non-oriented film.
[23] In another embodiment, the present invention provides a release film for PCB lamination processes, which is obtained by laminating a layer B, consisting of polypropylene resin (PP), on one side of a layer A, consisting of a non-oriented film made of polyethylene terephthalate (PET).
[24] Preferably, the inventive release film is obtained by laminating another layer B, consisting of polypropylene (PP) resin, on the other side of said layer A.
[25] Preferably, the inventive release film is obtained by laminating a layer C, consisting of polyethylene (PE) resin, on the other side of said layer A.
[26] Preferably, said layer A of the inventive release film contains a polyester elastomer based on polybutylene terephthalate.
[27] Preferably, said layer B of the inventive release film contains at least one selected from among ethylene and 1-butene. [28] Preferably, said layer A of the inventive release film has a thickness of 10-100 D.
[29] Preferably, said layer B of the inventive release film has a thickness of 2- 15 D.
[30] Preferably, said layer C of the inventive release film has a thickness of 100-300 D.
Advantageous Effects
[31] The present invention provides an excellent release film, which resists pressing conditions of high temperature and high pressure and, at the same time, has excellent releasability from a polyimide film as a cover layer and does not substantially transfer material to the PCB or the cover layer. [32] Also, the inventive release film provides an excellent effect of reducing the failure rate of a lamination process, because it does not react with epoxy resin or acrylic resin. [33] Particularly, the inventive release film has properties similar or superior to an expensive PMP material that has been used in the prior art.
Brief Description of the Drawings
[34] FIG. 1 is a schematic diagram showing one example of a PCB lamination process.
[35] FIG. 2 is a cross-sectional view of a release film according to one embodiment of the present invention. [36] FIG. 3 is a cross-sectional view of a release film according to another embodiment of the present invention. [37] FIG. 4 is a cross-sectional view of a release film according to still another embodiment of the present invention.
Best Mode for Carrying Out the Invention [38] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. [39] FIG. 2 is a cross-sectional view of a release film according to one embodiment of the present invention. [40] The conventional work conditions of PCB lamination processes are as follows: work temperature: 130-180 0C; pressure: 40-90 kgf/cm ; and pressing time: about 60 minutes. [41] Thus, the release film for PCB lamination processes must be able to resist the above work conditions and, at the same time, must have excellent releasability from a polyimide film as a cover layer and have high purity such that no material is transferred from the release film to the PCB or the cover layer. [42] Particularly, in an actual lamination process, an adhesive can flow out through the open cells 102 (FIG. 1) of the polyimide film 120 (FIG. 1) due to the pressure of the press. For this reason, in order to transfer the pressure of the press uniformly over the entire area of the cover layer, the release film must be suitably flexible but not be reactive with epoxy resin or acrylic resin, which is used as an adhesive. [43] In view of this point, the inventive release film has the configuration shown in FIG.
2, and is obtained by laminating layer B, consisting of polypropylene (PP) resin, on one side of layer A, consisting of either a film made of any one selected from the group consisting of polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), or a non-oriented film made of polyethylene terephthalate (PET).
[44] Said polycarbonate resin has excellent heat resistance, and thus does not melt at the above-described work temperature, and provides excellent elongation (flexibility), so that it enables the pressure of the press to be applied uniformly over the entire surface of the polyimide film acting as the cover layer. It is preferable for the present invention to use polycarbonate resin having a glass transition temperature (Tg) of 130-180 0C, and more preferably about 150 0C.
[45] Materials usable as the polycarbonate resin in the present invention include straight- chain polymers, branched-chain polymers, high-heat-resistant polymers containing phthalate for increasing the heat resistance thereof, and silicon copolymers having increased impact resistance, and preferably have a viscosity-average molecular weight (Mv) of 15000-30000 corresponding to a melt flow index of 1-50, as measured under conditions of 300 0C and 1.2 kg.
[46] Because the glass transition temperature (Tg) and melt flow index of the polycarbonate resin change depending on the molecular weight and the kind of material added for polymerization, the molecular weight must be within a suitable range.
[47] If polycarbonate resin having a viscosity- average molecular weight of less than
15000 is used, it shows a decreased glass transition temperature of less than 135 0C, and also increased melt flow index, making it difficult to carry out the PCB lamination process and film forming process at high temperature. On the other hand, if polycarbonate resin having a viscosity-average molecular weight of more than 30000 is used, its heat resistance is improved, but its melt flow index is decreased to less than 1, making a film formation process difficult.
[48] In the case of an oriented polyethylene terephthalate film according to the prior art, it is biaxially oriented and thermally treated, and thus has increased thermal resistance and is prevented from thermally shrinking. However, because the oriented film has excessively high stiffness, it will have reduced pressability in the fabrication of a PCB having a complicated structure.
[49] In comparison with this, polycarbonate resin can be maintained at a glass transition temperature of about 150 0C without the need to conduct orientation, and thus shows good pressability compared to the oriented film, even when it is used in the fabrication of a PCB having a complicated structure. Also, because polycarbonate resin is a completely amorphous resin, it is not crystallized even under high-temperature heat treatment conditions, and thus it does not shrink, thus exhibiting good properties for use as a release film.
[50] Materials usable as the polybutylene terephthalate (PBT) resin in the present invention include straight-chain polymers, branched-chain polymers, and high- heat-resistant polymers containing a naphthalenic compound for increasing the heat resistance thereof, and preferably have an intrinsic viscosity (LV) ranging from 0.5 dl/ g to 1.5 dl/g. If polybutylene terephthalate, having a viscosity lower than 0.5 dl/g, is used, it has an excessively high flow index, which makes the film formation process difficult, and if polybutylene terephthalate, having a viscosity higher than 1.5 dl/g, is used, it shows decreased flow index, which increases the roughness of a film surface in a film forming process and reduces work efficiency.
[51] Polybutylene terephthalate resin, after being extruded into a film, shows excellent elongation (flexibility) and toughness whether at high temperature or room temperature, so that it can show excellent pressability upon the fabrication of a complicated and fine circuit board. Also, polybutylene terephthalate (PBT) shows a melting behavior in which it is well miscible with polycarbonate (PC) in the full temperature range. For this reason, there was an example in which polybutylene terephthalate was used in a mixture with polycarbonate in a material for electrical/ electronic components in order to improve the inferior chemical resistance of polycarbonate, but there is still no example in which polybutylene terephthalate is applied to a release film as disclosed in the present invention.
[52] Particularly, in the inventive release film, in order to prevent chemical damage to polycarbonate caused by an acrylic or epoxy resin adhesive component applied to the inside of the cover layer and by the remaining solvent during a PCB lamination process, the polycarbonate can be used in a mixture with polybutylene terephthalate to improve the chemical resistance of the release film.
[53] Materials usable as polyethylene terephthalate (PET) resin in the present invention include straight-chain polymers, branched-chain polymers, and high-heat-resistant polymers containing a naphthalenic compound for increasing the heat resistance thereof, and preferably have an intrinsic viscosity (LV.) ranging from 0.5 dl/g to 1.0 dl/ g. Although PET generally has a glass transition temperature of about 75 0C, it can be imparted with a glass transition temperature of 75-125 0C by using a naphthalenic compound, and thus can be used in various applications depending on its heat resistance.
[54] If polyethylene terephthalate having an intrinsic viscosity lower than 0.5 dl/g is used, it shows low melt tension and an excessively high melt index, making the film forming process difficult, and if polyethylene terephthalate having a viscosity greater than 1.0 dl/g is used, it shows a low flow index, also making the film forming process difficult.
[55] When polyethylene terephthalate alone is extruded into a non-oriented film, the film itself has very low strain, and thus has an excellent effect of preventing PCB shrinkage caused by the shrinkage of the release film after a PCB lamination process, and has excellent pressability in the fabrication of a PCB having a complicated structure. However, the film formed from polyethylene terephthalate has slightly reduced pro- cessability due to poor toughness, and is brittle, leading to a reduction in productivity. However, these disadvantages can be mitigated through the toughness and excellent elongation of polycarbonate (PC) or polybutylene terephthalate (PBT) by mixing it with polycarbonate and polybutylene terephthalate, considering that it shows a melting behavior in which it is well miscible with polycarbonate and polybutylene terephthalate.
[56] Meanwhile, said layer A is preferably structured such that it contains a polyester elastomer based on polybutylene terephthalate.
[57] Although an increase in the content of the polyester elastomer in the layer A leads to a reduction in the heat resistance of the layer A, the polyester elastomer serves to improve pressability so as to increase the adhesion of the polyimide film to the fine portions of PCB, even under conditions of process temperatures lower than existing products. As the polyester elastomer, it is preferable for the present invention to use a polyester elastomer based on polybutylene terephthalate, having a melting point of more than 150 0C and a Shore hardness of more than 30.
[58] Specifically, the polyester elastomer resin based on polybutylene terephthalate is prepared through a melt polycondensation process, as in the case of preparing polybutylene terephthalate or polyethylene terephthalate. In the initial stage of a reaction for preparing the polyester elastomer, it is preferable to add polyte- tramethylene etherglycol (PTMEG) as a comonomer in an amount of 5-60 wt% based on the total weight of the reaction materials, in order to impart an elastomeric property. If poly tetrame thy lene etherglycol is used in an amount of less than 5 wt%, the resulting polymer will have insufficient elastomeric properties due to the low elastomer content, and if polytetramethylene etherglycol is used in an amount more than 60 wt%, it will make polymerization difficult and result in a reduction in the melting point, and thus will be unsuitable for the object of the present invention. The polytetramethylene etherglycol (PTMEG), which is used as a comonomer in the present invention, may have various molecular weights, and generally a number- average molecular weight (Mn) of 1000-3000. Because the melting point and hardness of the resulting elastomer change depending on the molecular weight and content of polytetramethylene etherglycol (PTMEG), it is important to select a suitable molecular weight and content of the polytetramethylene etherglycol.
[59] The melting point of the polyester elastomer changes depending on the molecular weight of the material used for copolymerization, even when the material is used in the same amount. Specifically, if a material having a low molecular weight is used, the melting point of the polyester elastomer will be decreased, and if a high- molecular- weight material is used, the melting point of the polyester elastomer will be increased. However, a material having a melting point of more than 150 0C and a Shore hardness (D scale) of more than 30 can be used in the present invention, regardless of the molecular weight and content thereof.
[60] In view of the above-described point, the layer A preferably contains the polyester elastomer in an amount of 0-50 parts by weight based on 30-100 parts by weight of one or more resins selected from among polycarbonate, polybutylene terephthalate, and polyethylene terephthalate. Particularly, the polyester elastomer is preferably contained in the layer A in an amount of 3-20 parts by weight, because an increase in the content thereof leads to an increase in die swell during extrusion, and a decrease in transparency.
[61] Also, to enhance the heat resistance of the release film in view of the pressing conditions of high temperature, high pressure and a long period of time, the layer A preferably contains an antioxidant in an amount of 0-5 parts by weight based on 30-100 parts by weight of either a film consisting of any one selected from among polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), or a non-oriented film consisting of polyethylene terephthalate (PET).
[62] The antioxidant is used to prevent resin pyrolysis, oxidation, crosslinking, discoloration and the like, which can occur during high-temperature processes such as a compounding extrusion or film extrusion process. For example, it is possible to use a conventional phenolic antioxidant as a primary antioxidant and to use a conventional phosphite or phosphonite antioxidant as a secondary antioxidant.
[63] The antioxidant, which is used in the present invention, is generally an antioxidant used for polycarbonate and polyester elastomers, and any antioxidant can be used in the present invention as long as it has excellent high heat resistance and excellent acid resistance, base resistance, oil resistance and the like. The present invention does not need to be limited to the above-exemplified antioxidants. [64] Meanwhile, although the inventive release film can be prepared in a non-oriented, uniaxially oriented or biaxially oriented state, it is particularly preferable to prepare the release film in a non-oriented state in view of pressability. Namely, the orientation of the release film should be easy to perform in order to increase the adhesion thereof to fine portions during a press adhesion process, but the oriented film shows a reduced orientation property during the adhesion process, because it is already highly oriented. However, because a non-oriented film is not yet oriented, it can be easily oriented during the pressing operation to increase the adhesion thereof to fine portions.
[65] The layer B consists of polypropylene (PP) resin.
[66] Polyolefin resins are generally known to have excellent chemical resistance, and particularly, polyolefin resins having excellent heat resistance, include cyclic olefin copolymers (COC), polymethylpentene (PMP) and the like. However, poly- methylpentene is disadvantageously expensive, although it has excellent properties. For this reason, in the present invention, polypropylene (PP) resin, having excellent heat resistance and general usefulness, is used.
[67] The polypropylene resin (PP) resin, which is used in the present invention, is structured such that it has a melting point of about 165 0C. Except for some cases where an adhesive for application to the polyimide film (i.e., cover layer) must be used at temperatures higher than 170 0C, the polypropylene resin shows good pressability at a temperature of about 165 0C. Thus, it enables satisfactory pressability to be realized, when a pressing temperature of 150-160 0C is applied.
[68] Specific examples of this polypropylene resin, which can be used in the present invention, include polypropylene homopolymers and polypropylene copolymers. The polypropylene copolymers can be in the form of random copolymers, block copolymers or graft copolymers.
[69] As described above, in an actual lamination process, an adhesive can flow out through the open cells 102 (FIG. 1) of the polyimide film 120 (FIG. 1) due to the pressure of the press, so that the release film can adhere to the polyimide film.
[70] For this reason, at least the surface of the release film that faces the polyimide film must be non-reactive with epoxy resin or acrylic resin as the adhesive agent. Because these resins exemplified as the adhesive agent are polar in nature, they are chemically incompatible with non-polar polyolefin. In view of this point, the layer B, consisting of polypropylene (PP) resin, is laminated on one side of the layer A, and the resulting film is deposited and pressed during the lamination process, such that the layer B faces the polyimide film.
[71] Meanwhile, the layer B is preferably structured such that it contains at least one of ethylene and 1-butene.
[72] Although ethylene or 1-butene reduces the melting point and heat resistance of the layer B according to an increase in the content thereof, it serves to increase the flexibility and press workability of the layer B. In view of this point, the layer B preferably contains at least one of ethylene and 1-butene in an amount of 0-7 parts by weight based on 93-100 parts by weight of polypropylene.
[73] Meanwhile, the layer A preferably has a thickness of 10-100 D, and more preferably
20-50 D. If the thickness of the layer A is smaller than 10 D, the pressability of the layer B can be reduced, and if it is larger than 100 D, the layer A can be damaged due to the difference in thermal expansion coefficient from PCB upon cooling after the pressing operation.
[74] Also, the layer B preferably a thickness of 2-15 D, and more preferably 5-10 D. If the layer B is thinner than 2 D, it will be difficult to form a film, and if it is thicker than 15 D, it will be excessively hard, resulting in a reduction in pressability.
[75] The layer A and layer B can be laminated to each other according to a conventional known method, such as dry lamination, extrusion lamination, or coextrusion, to form one film.
[76] FIG. 3 is a cross-sectional view of a release film according to another embodiment of the present invention.
[77] According to another embodiment of the present invention, the inventive release film for PCB lamination processes is obtained by laminating another layer B consisting of polypropylene (PP) resin on the other side of the layer A having the layer B laminated on one side thereof.
[78] Specifically, the layer B is laminated on both surfaces of the layer A made of a non- oriented film consisting of any one selected from among polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin, a mixed resin of polycarbonate (PC) and polybutylene terephthalate (PBT), a mixed resin of polycarbonate (PC) and polyethylene terephthalate (PET), a mixed resin of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and a mixed resin of polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), or a non- oriented film consisting of a polyethylene terephthalate (PET). In this case, there is an advantage in that a worker can perform a lamination process without the need to consider whether the layer B faces the polyimide film as the cover layer.
[79] Herein, the structure, thickness and the like of each of the layer A and layer B can be the same as described above.
[80] FIG. 4 is a cross-sectional view of a release film according to still another embodiment of the present invention.
[81] According to still another embodiment of the present invention, the inventive release film for PCB lamination processes is obtained by laminating layer C, consisting of polyethylene (PE) resin, on the other side of the layer A having the layer B laminated on one side thereof.
[82] In this lamination structure, the layer C consisting of polyethylene (PE) resin can also function as the PVC sheet (or PE sheet) provided on the press unit of FIG. 1, i.e., a buffer layer.
[83] Specifically, as described above, the press unit is provided above and below the
PCB 100 during the lamination process, and has a structure in which the paper sheet 310 and the flexible PVC sheet 320 are sequentially formed inside the steel plate 300. Also, the release film 200 is located between each of the press units and the polyimide film 210 adhered to the PCB 100.
[84] Thus, when the layer C, consisting of polyethylene (PE) resin as a buffer layer, is laminated on the release film surface, which faces the press unit, the press unit does not need to be provided with a separate buffer layer, such as the PVC sheet 320.
[85] Particularly, considering that the paper sheet 310, the PVC sheet 320 as a buffer, and the release film are disposed of as waste, the release film having the layer C formed thereon can be laminated alone between the paper sheet 310 and the polyimide film 120 without using the PVC sheet 320, and the resulting structure can be subjected to a pressing operation.
[86] In this case, because the layer C is not brought into direct contact with the polyimide film 120 and the heat resistance thereof does not need to be considered, it is formed by laminating polyethylene (PE) resin, which is used as a conventional buffer. The polyethylene (PE) resin has a characteristic of being easily laminated to polycarbonate resin (PC).
[87] The film or sheet, used as the conventional buffer, has a thickness of more than 100
D. As the buffer polyethylene, low-density polyethylene or linear low-density polyethylene having a density of less than 0.93 g/cm is generally used, and the densities or fundamental properties of these resins will vary depending on the catalyst and the method used for the preparation thereof. Such polyethylene has a melting point of 100-120 0C, which is lower than the temperature of the pressing process, and thus it can be melted to impart pressability thereto.
[88] To provide a sufficient buffer property, the layer C preferably has a thickness of about 100-300 D, and more preferably 120-200 D in view of economic efficiency. Mode for the Invention
[89] Hereinafter, the present invention will be described in further detail with reference to examples. However, these examples are not intended to limit the scope of the present invention.
[90] Examples
[91] Polycarbonate films were prepared in the following manner. First, the following components were mixed well with each other: 68 parts by weight of TRIREX 3026 (branched copolymer, commercially available from Samyang Corporation, Korea; density: 1.2 g/cm ; MI: 0.81 g/10 min (300 0C, 1.2 kg); glass transition temperature: 148 0C); 23 parts by weight of TRIREX 3020 (Samyang Corporation, Korea; density: 1.2 g/cm3; MI: 10 g/10 min (300 0C, 1.2 kg); Vicat softening temperature: 144 0C); 9 parts by weight of TRIEL 5400 (polybutylene terephthalate-based polyester elastomer commercially available from Samyang Corp., Korea; density: 1.15 g/cm ; MI: 14 g/10 min (230 0C, 2.16 kg); melting point: 205 0C), 0.1 parts by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 parts by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals). The mixture was extruded in a twin extruder (47 m/m, L/D 48) at a temperature of 250-280 0C. The extruded material was formed into non-oriented films having 30, 35 and 40 D, respectively, using a T-die casting (110 m/m, L/D 32) method at an extruder temperature of 270-300 0C.
[92] A polybutylene terephthalate film was prepared in the following manner. First, the following materials were mixed well with each other: 100 parts by weight of TRIBIT 1700 (commercially available from Samyang Corp., Korea; density: 1.31 g/cm ; MI: 20 g/10 min (260 0C, 2.16 kg); glass transition temperature: 148 0C); 0.1 parts by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 parts by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals). The mixture was extruded in a twin extruder (47 m/m, L/D 48) at a temperature of 220-250 0C). The extruded material was formed into a non-oriented film having a thickness of 35 D, using a T-die casting method 110 m/m, L/D 32) at an extruder temperature of 230-260 0C.
[93] A polybutylene terephthalate film was prepared in the following manner. First, the following materials were mixed well with each other: 95 parts by weight of TRIBIT 1700 (commercially available from Samyang Corp., Korea; density: 1.31 g/cm ; MI: 20 g/10 min (260 0C, 2.16 kg); glass transition temperature: 148 0C); 5 parts by weight of TRIEL 5400 (commercially available from Samyang Corp., Korea; density: 1.25 g/ cm3; MI: 14 g/10 min (235 0C, 2.16 kg); glass transition temperature: -20 0C); 0.1 parts by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 parts by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals). The mixture was extruded in a twin extruder (47 m/m, L/D 48) at a temperature of 220-250 0C. The extruded material was formed into a non-oriented film having a thickness of 35 D, using a T-die casting (110 m/m, L/D 32) method at an extruder temperature of 230-260 0C.
[94] A film consisting of a mixture of polycarbonate and polybutylene terephthalate was prepared in the following manner. First, the following materials were mixed well with each other: 65 parts by weight of TRIREX 3026 (Samyang Corp., Korea); 30 parts by weight of TRIBIT 1700 (Samyang Corp., Korea); 5 parts by weight of TRIEL (Samyang Corp., Korea); 0.1 part by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 part by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals). The mixture was extruded in a twin extruder (47 m/m, L/D 48) at a temperature of 240-290 0C. The extruded material was formed into a non-oriented film having a thickness of 35 D using a T-die casting (110 m/m, L/D 32) method at an extruder temperature of 250-300 0C.
[95] A film consisting of a mixture of polycarbonate and polyethylene terephthalate was prepared in the following manner. First, the following components were mixed well with each other: 50 parts by weight of TRIREX 3026 (Samyang Corp., Korea); 20 parts by weight of TRIREX 3020 (Samyang Corp., Korea); 15 parts by weight of polyethylene terephthalate (commercially available from Huvis; intrinsic viscosity: 0.65 dl/g); 5 parts by weight of TRIEL (Samyang Corp., Korea); 0.1 part by weight of Songnox 1010 (antioxidant commercially available from Songwon Industrial Co., Ltd., Korea); and 0.1 part by weight of Irganox 168 (antioxidant commercially available from Ciba Specialty Chemicals). The mixture was extruded in a twin extruder (47 m/ m, L/D 48) at a temperature of 240-290 0C. The extruded material was formed into a non-oriented film having a thickness of 35 D using a T-die casting (110 m/m, L/D 32) method at an extruder temperature of 250-300 0C.
[96] Polypropylene films were prepared by extruding 5014 HPT (commercially available from Korea Petrochemical Ind. Co., Ltd.; density: 0.9 g/cm3; MI: 2.5 g/10 min (230 0C, 2.16 kg); melting point: 165 0C) at an extruder temperature of 190-250 0C at Samyoung Chemical Co., Ltd., Korea, thus obtaining biaxially oriented films having thickness of 5, 8 and 12 D, respectively. Also, a 20-D thick polypropylene film was prepared by extruding 5014L (commercially available from Korea Petrochemical Ind. Co., Ltd.; density: 0.9 g/cm3; MI: 3.0 g/10 min (230 0C, 2.16 kg); melting point: 165 0C) at Samyoung Chemical Co., Ltd., Korea, thus obtaining a biaxially oriented polypropylene film.
[97] A 130-D thick polyethylene film was prepared by extruding 5304 (commercially available from Hanwha Petrochemical Corp., Korea; density: 0.923 g/cm ; MI: 0.3 g/ 10 min (190 0C, 2.16 kg); melting point: 112 0C) at an extruder temperature of 180-230 0C using an upward inflation process.
[98] Lamination of the above-prepared polycarbonate film with the above-prepared polypropylene film was performed using a mixture of a polyurethane adhesive and a curing agent, according to a dry lamination process.
[99] In Example 1, the 5-D thick polypropylene film was laminated on one side of the 40-D thick polycarbonate film. [100] In Example 2, the 8-D thick polypropylene film was laminated on both sides of the
35-D polycarbonate film. [101] In Example 3, the 12-D thick polypropylene film was laminated on both sides of the
30-D thick polycarbonate film. [102] In Example 4, the 20-D thick polypropylene film was laminated on both sides of the
30-D thick polycarbonate film. [103] In Example 5, the 12-D thick polypropylene film was laminated on one side of the
40-D thick polycarbonate film, and then the 130-D thick low-density polyethylene film was laminated on the opposite side of the 40-D thick polycarbonate film according to a dry lamination process. [104] In Example 6, the 8-D thick polypropylene film was laminated on both sides of the
35-D thick polybutylene terephthalate film. [105] In Example 7, the 8-D thick polypropylene film was laminated on both sides of the
35-D polybutylene terephthalate film. [106] In Example 8, the 8-D polypropylene film was laminated on both sides of the 35-D thick mixed film of polycarbonate and polybutylene terephthalate. [107] In Example 9, the 8-D polypropylene film was laminated on both sides of the 35-D thick mixed film of polycarbonate and polyethylene terephthalate. [108] In Comparative Example 1, OPULENT TPX (commercially available from Mitsui
Chemical Co.; density: 0.835 g/cm ; melting point: 235 0C; thickness: 50 D; Vicat softening point: 160 0C), prepared from poly 1-methylpentene, was used. [109] In Comparative Example 2, a film obtained by dry laminating the 12-D thick polypropylene film on both sides of a biaxially oriented polyethylene terephthalate film (commercially available from Hwaseung Industries Co., Ltd., Korea; density: 1.4 g/cm ; thickness: 25 D) was used. [110] In Comparative Example 3, a both side silicone-coated polyethylene terephthalate film (commercially available from Toray Saehan Inc., Korea; silicone coating amount:
1.5 g/1 m ) was used. [I l l] Test Example
[112] The physical properties of the films prepared in Examples 1-9, and the films used in
Comparative Examples 1-3, were measured in the following manner. [113] ( 1 ) Resin flow was measured.
[114] Resin flow is measured as the length of an adhesive that flows out through the open cell of a cover layer (polyimide film) during a pressing operation. Increased resin flow value can show reduced pressability and has an increased possibility of causing plating failures in a process of plating PCB circuits. [115] The following operation conditions were used based on a circuit line width of 100 D: 160 0C, 50 kgf/cm , 60 min.
[116] The measurement of resin flow was performed by measuring the length at which resin flowed out, using a micrometer marked on a microscope (OLYMPUS SZ61, x80).
[117] (2) The delamination of the cover layer was measured.
[118] The following operation conditions were used based on a circuit line width of 100 D:
160 0C, 50 kgf/cm , 60 min. The number of circuits having induced delamination per 100 circuits was measured with a microscope, in which five optional circuits were measured and the measurement results were recorded as average values.
[119] (3) Platability was measured.
[120] Platability indicates the excellence of a plating process, and transferability from the release film.
[121] To the open cell portion of PCB subjected to electroless gold plating, a 25-mm wide adhesive tape (610, 3M Company) was adhered closely with a force of 2 kg to make a test sample. The test sample was applied with a pressure of 20 g/cm in an oven at 70 0C for 10 hours, and then left to stand at room temperature for about 15 minutes. Then, the tape was separated manually and the surface thereof was observed with a microscope (OLYMPUS SZ61, x80) to determine whether the gold plate layer had peeled. If the plate layer was observed to have any peeled portion, it was evaluated as "poor".
[122] (4) Releas ability was measured.
[123] Releasability in a disassembly operation after a pressing process was observed. As used herein, the "disassembly operation" refers to a process of disassembling elements manually from each other after sufficient cooling following a pressing process at high temperature and high temperature. Smaller peel strength between the cover layer and the release film can show better releasability.
[124] The process of measuring releasability was manually carried out on a release film adhered to the FPCB. The case of easy separation of the release paper by a manual operation was evaluated as "good", and the case of the occurrence of wrinkles in FPCB due to non-smooth separation of the release paper was evaluated as "poor".
[125] The measurement results are shown in Tables 1 and 2 below.
[126] Table 1
Figure imgf000016_0001
Figure imgf000017_0001
[127] [128] Table 2
[129] As could be seen in Tables 1 and 2, the release films prepared according to Examples 1-9 of the present invention had excellent resin flow properties. Particularly, these release films showed resin flow properties similar to or slightly better than the PMP material which has been used in the prior art.
[130] Also, the release films prepared according to Examples 1-9 of the present invention were similar or superior to Comparative Examples 1-3 with respect to delamination, platability and releasability.
[131] Also, in the prior art, when a PVC sheet, paper, release film, PCB circuit board or the like are laminated on each other during a pressing process, there occurs a phenomenon in which the release film leans to one side during pressurization or de- pressurization depending on the friction factor of the release film. However, the release films prepared according to Examples 1-9 of the present invention did not show this phenomenon, suggesting that these films had good lamination properties.
[132] The present invention can be carried out in various other embodiments without deviating from the sprit or main features thereof. For this reason, the foregoing Examples are merely illustrative in all respects and are not to be construed as being limiting.
[133]
[134]

Claims

Claims
[I] A release film for PCB lamination processes, which is obtained by laminating a layer B, consisting of polypropylene (PP) resin, on one side of a layer A, consisting of polycarbonate (PC) resin.
[2] The release film of Claim 1, wherein the layer A is a non-oriented film.
[3] A release film for PCB lamination processes, which is obtained by laminating a layer B, consisting of polypropylene (PP) resin, on one side of a layer A, consisting of polybutylene terephthalate (PBT) resin.
[4] The release film of Claim 3, wherein the layer A is a non-oriented film.
[5] A release film for PCB lamination processes, which is obtained by laminating a layer B, consisting of a polypropylene (PP) resin, on one side of a layer A, consisting of a non-oriented film made of polyethylene terephthalate (PET) resin. [6] A release film for PCB lamination process, which is obtained by laminating a layer B, consisting of polypropylene (PP) resin, on one side of a layer A, consisting of two or more selected from among polycarbonate (PC), polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) resins. [7] The release film of Claim 6, wherein the layer A is a non-oriented film.
[8] The release film of any one of Claims 1 to 7, which is obtained by laminating another layer B consisting of polypropylene (PP) resin on the other side of the layer A. [9] The release film of any one of Claims 1 to 7, which is obtained by laminating a layer C, consisting of polyethylene (PE) resin, on the other side of the layer A. [10] The release film of any one of Claims 1 to 7, wherein the layer A contains a polyester elastomer based on polybutylene terephthalate.
[I I] The release film of any one of Claims 1 to 7, wherein the layer B contains any one selected from among ethylene and 1-butene.
[12] The release film of any one of Claims 1 to 7, wherein the layer A has a thickness of 10-100 D. [13] The release film of any one of Claims 1 to 7, wherein the layer B has a thickness of 2-15 D. [14] The release film of any one of Claim 9, wherein the layer C has a thickness of
100-300 D.
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CN108235594A (en) * 2016-12-09 2018-06-29 松本涂层科技（昆山）有限公司 A kind of combined type folds structure release film and preparation method thereof

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