Flexible laminates, polyester films, flexible flat cables, flexible electronic substrates

Abstract

The flexible laminate according to the embodiment includes a heat-resistant layer and a conductive layer disposed on at least one surface of the heat-resistant layer, the heat-resistant layer including a cyclohexanedimethanol residue, a terephthalic acid residue, and an isophthalic acid residue, and when T1 is a temperature between 230°C and 245°C and T2 is a temperature of 210°C, K is expressed by the following formula 1-1: HS The value is between 0.1 and 12. [Formula 1-1] JPEG2026504305000016.jpg1252In the above formula 1-1, K HS is the variation index (% / °C) of the thermal shrinkage rate of the heat-resistant layer, T1 and T2 are the Celsius temperatures (°C) defined above, and HS T1 and H.S. T2 are the thermal shrinkage rates (%) in one direction of the surface of the heat-resistant layer before and after heat treatment for 10 minutes at T1 and T2, respectively. The flexible laminates, polyester films, flexible electronic boards, etc. according to the embodiments have excellent properties such as heat resistance, moisture resistance, and dimensional stability, and are highly applicable to flexible copper clad laminates (FCCL), flexible printed circuit boards (FPCB), flexible flat cables (FFC), etc.

Description

[Technical Field]

[0001] Examples of the present invention include flexible laminates, polyester films, flexible flat cables, and flexible electronic substrates, which have excellent heat resistance, moisture resistance, and dimensional stability. [Background technology]

[0002] Recently, flexible printed circuit boards (FPCBs) have become the mainstream of electronic substrates such as printed circuit boards (PCBs). Because these flexible printed circuit boards are thin yet flexible, they are used as components suitable for miniaturizing and reducing the weight of electronic devices such as smartphones and laptops.

[0003] Generally, flexible printed circuit boards (FPCBs) are manufactured using a flexible laminate in which an electrically conductive layer (conductive layer) is laminated on one or both sides of an insulating substrate layer. A flexible laminate in which copper foil is used as the conductive layer is called a flexible copper clad laminate (FCCL). A flexible printed circuit board (FPCB) is manufactured by forming a conductive pattern by etching the conductive layer of the flexible laminate.

[0004] In such flexible laminates, films such as liquid crystal polymer (LCP) film, polyethylene naphthalate (PEN) film, polyimide (PI) film, etc. are mainly used as the substrate layer. However, these films have problems such as high unit cost and insufficient heat resistance and moisture resistance, and therefore, new materials that can replace them are required.

[0005] Recently, in order to reduce the weight of automobiles and other means of transportation, metal materials have been replaced with plastic materials, and these plastic materials are being used in parts of electric and electronic devices, including flexible flat cables (FFCs). While polyethylene terephthalate (PET) films have traditionally been used as such plastic materials, there are problems with PET films, such as insufficient heat resistance, and therefore there is a demand for alternative materials.

[0006] The above content is technical information that the inventor possessed in order to derive an embodiment of the present invention or that he acquired in the process of deriving it, and is not necessarily publicly known technology that was made public to the general public prior to the filing of the present application.

[0007] Related prior art includes (Patent Document 1) Korean Patent Publication No. 10-2009-0059457 and (Patent Document 2) Korean Patent Registration No. 10-1275159. Summary of the Invention [Problem to be solved by the invention]

[0008] The objective of the present embodiment is to provide a flexible laminate, polyester film, and flexible flat cables and flexible electronic boards including the same, which maintain a low thermal shrinkage rate without significant change over a wide high temperature range, are substantially free of warping or distortion, and have excellent heat resistance, moisture resistance, and dimensional stability, and are applicable to flexible flat cables (FFCs), flexible copper clad laminates (FCCLs), flexible printed circuit boards (FPCBs), etc. [Means for solving the problem]

[0009] According to one or more embodiments, a flexible laminate includes a heat-resistant layer and a conductive layer disposed on at least one surface of the heat-resistant layer, the heat-resistant layer including a cyclohexanedimethanol residue, a terephthalic acid residue, and an isophthalic acid residue, and when T1 is a temperature between 230°C and 245°C and T2 is a temperature of 210°C, K is expressed by the following formula 1-1: HS The value is between 0.1 and 12.

[0010] [Formula 1-1] JPEG2026504305000002.jpg1253

[0011] In the formula 1-1, K HS is the variation index (% / °C) of the thermal shrinkage rate of the heat-resistant layer, T1 and T2 are the Celsius temperatures (°C) defined above, and HS T1 and H.S. T2 are the thermal shrinkage rates (%) of the heat-resistant layer when heat-treated at T1 and T2 for 10 minutes, respectively.

[0012] According to one or more embodiments, the flexible laminate may have a heat shrinkage rate of 8% or less of the heat-resistant layer when heat-treated at 245°C for 10 minutes.

[0013] According to one or more embodiments, the flexible laminate may have a heat shrinkage rate of 0.5% or less of the heat-resistant layer when heat-treated at 150°C for 30 minutes.

[0014] The flexible laminate according to one or more embodiments may have a dimensional change rate of 1% or less according to the following Equation 3:

[0015] [Formula 3] Dimensional change rate (%) = 100 x (L0'-L') / L0'

[0016] In the above formula 3, L0' is the length of the flexible laminate before the flexible laminate is heat-treated, and L' is the length of the flexible laminate after the flexible laminate is annealed, and the annealing involves heat-treating the flexible laminate at 150°C for 30 minutes and then leaving it at a temperature of 23°C to 25°C for at least 1 hour.

[0017] According to one or more embodiments, the flexible laminate may have a curl of less than 3 mm after being heat-treated at 150° C. for 30 minutes.

[0018] According to one or more embodiments, the polyester film contains cyclohexanedimethanol residues, terephthalic acid residues, and isophthalic acid residues, and has a K" according to the following formula 1-2 when T1 is a temperature between 230°C and 245°C and T2 is a temperature of 210°C: HS The value is between 0.1 and 12.

[0019] [Formula 1-2] JPEG2026504305000003.jpg1159

[0020] In the formula 1-2, K" HS is the variation index (% / °C) of the heat shrinkage rate of the polyester film, T1 and T2 are the Celsius temperatures (°C) defined above, and HS" T1 and HS" T2 are the heat shrinkage rates (%) of the polyester film when heat treated at T1 and T2 for 10 minutes, respectively.

[0021] The polyester film according to one or more embodiments may have a moisture absorption rate of 1% or less.

[0022] A flexible flat cable according to one or more embodiments includes the flexible laminate described above.

[0023] According to one or more embodiments, the flexible flat cable includes the polyester film described above.

[0024] A flexible electronic substrate according to one or more embodiments includes the flexible laminate described above. [Effects of the Invention]

[0025] The flexible laminate according to the embodiment has excellent heat resistance, moisture resistance, etc., and can maintain excellent performance even when repeatedly exposed to harsh conditions such as high temperatures for a long period of time.

[0026] The flexible laminate according to the embodiment has excellent dimensional stability, heat resistance, and the like, and is substantially free from warpage such as curling, so that it can have excellent workability and processability.

[0027] The polyester film according to the embodiment has excellent heat resistance, moisture resistance, etc., and can maintain excellent performance even when repeatedly exposed to harsh conditions such as high temperatures for a long period of time.

[0028] The flexible flat cable according to the embodiment includes the flexible laminate or polyester film, and therefore can maintain excellent performance even when repeatedly exposed to harsh conditions such as high temperatures for a long period of time.

[0029] The flexible electronic substrate according to the embodiment includes the flexible laminate or the polyester film, so that it does not warp, can maintain excellent performance even when repeatedly exposed to harsh conditions for a long period of time, and can have an excellent signal transmission rate in a high-frequency environment. [Brief explanation of the drawings]

[0030] [Figure 1] 1A, 1B, and 1C are conceptual diagrams illustrating cross sections of flexible laminates according to embodiments. [Figure 2] 1A, 1B, and 1C are conceptual diagrams illustrating cross sections of flexible laminates according to embodiments. [Figure 3] 3 is a conceptual diagram illustrating a method for measuring the degree of warpage of a flexible laminate through a CV (Curl Value) of the flexible laminate according to an embodiment. FIG. [Figure 4] 1 is a schematic diagram illustrating a cross-section of a polyester film according to one or more embodiments. BEST MODE FOR CARRYING OUT THE INVENTION

[0031] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. The same reference numerals are used throughout the specification to refer to similar parts.

[0032] In this specification, when a certain configuration "includes" another configuration, this does not mean that it excludes the other configurations, and that it may further include the other configurations, unless otherwise specified.

[0033] In this specification, when a certain component is said to be "connected" to another component, this includes not only the case where the components are "directly connected" but also the case where the components are "connected via another component between them."

[0034] In this specification, the term "B is located on A" means that B is located on A in direct contact with A, or that B is located on A with another layer located therebetween, and is not to be interpreted as being limited to B being located in contact with the surface of A.

[0035] In this specification, the term "B is located below A" means that B is located below A in direct contact with A, or that B is located below A with another layer located therebetween, and is not to be interpreted as being limited to B being located in contact with the surface of A.

[0036] As used herein, the term "combinations thereof" contained in a Markush expression means a mixture or combination of one or more elements selected from the group of elements set forth in the Markush expression, and means including one or more elements selected from the group of elements.

[0037] In this specification, unless otherwise specified, the unit of ppm is based on weight.

[0038] All numerical ranges indicating physical properties, dimensions, etc. of components described herein should be understood to be modified in all cases by the term "about" unless otherwise specified.

[0039] As used herein, the term "residue" refers to a certain portion or unit derived from a specific compound that is contained in the result of a chemical reaction when the specific compound is involved in the chemical reaction. For example, a dicarboxylic acid "residue" or a diol "residue" may refer to a portion derived from a dicarboxylic acid component or a portion derived from a diol component in a polyester formed by an esterification reaction or a polycondensation reaction, respectively.

[0040] As used herein, "curl" refers to the degree of warping of a manufactured film, flexible laminate, etc., and more specifically, refers to the degree to which the surface of the film, etc. is separated from the ground due to such warping.

[0041] In this specification, "flexible" means the property of being able to flexibly deform without tearing or breaking even when a tensile force is applied by bending, folding, etc. Therefore, in this specification, a flexible laminate, a flexible electronic substrate, etc. refer to a laminate and an electronic substrate having such flexibility, respectively.

[0042] There is a great demand for insulating films with sufficient heat resistance, moisture resistance, dimensional stability, etc. As the number of devices that utilize electricity, such as electrical and electronic devices and electric vehicles, increases, there is a demand for insulating films that can maintain their insulating functionality for long periods of time despite being exposed to various environments, especially repeated heat. In particular, insulating films used in electrical and electronic device components such as FCCLs, FPCBs, and FFCs require films with even stronger durability, such as heat resistance, moisture resistance, and dimensional stability, than insulating films previously studied.

[0043] Polyethylene naphthalate (PEN) films and polyimide (PI) films have been used for this purpose, but they have limitations in their heat resistance temperature and economic viability. Some polyethylene terephthalate (PET) films are also used in the manufacture of FFCs, but dimensional stability and heat resistance under increasingly severe conditions are required. The inventors have confirmed that by controlling the stretching, heat setting, relaxation rate, etc. during the film manufacturing process, they can obtain films with improved durability, such as dimensional stability, even at higher temperatures. They also demonstrate low curl characteristics when bonded to an electrically conductive layer such as copper, and present specific examples.

[0044] 1(a), 1(b), and 1(c) are conceptual diagrams illustrating cross sections of flexible laminates according to embodiments, 2(a), 2(b), and 2(c) are conceptual diagrams illustrating cross sections of flexible laminates according to embodiments, and 3(a), 3(b), and 3(c) are conceptual diagrams illustrating a method for measuring the degree of warpage of flexible laminates through the curl value (CV) of the flexible laminates according to embodiments. Hereinafter, embodiments will be described in more detail with reference to the drawings.

[0045] Flexible Laminate The flexible laminate 100 according to one embodiment includes a heat-resistant layer 10 and a conductive layer 20 disposed on at least one surface of the heat-resistant layer. the heat-resistant layer 10 contains a cyclohexanedimethanol residue, a terephthalic acid residue, and an isophthalic acid residue; When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 210°C, K HS The value is between 0.1 and 12.

[0046] [Formula 1-1] JPEG2026504305000004.jpg1159

[0047] In the formula 1-1, K HS is the variation index (% / °C) of the thermal shrinkage rate of the heat-resistant layer, T1 and T2 are the above-mentioned Celsius temperatures (°C), and HS T1 and H.S. T2 are the thermal shrinkage rates (%) in one direction of the surface of the heat-resistant layer before and after heat treatment for 10 minutes at T1 and T2, respectively.

[0048] The heat-resistant layer 10 contains cyclohexanedimethanol residues, terephthalic acid residues, and isophthalic acid residues.

[0049] Specifically, the cyclohexanedimethanol residue may be a 1,4-cyclohexanedimethanol residue.

[0050] The heat-resistant layer 10 may include a polyester film containing diol residues and dicarboxylic acid residues.

[0051] The polyester film is manufactured from a polyester resin composition containing a polyester resin obtained by polymerizing a diol and a dicarboxylic acid, and the polyester film contains a diol residue and a dicarboxylic acid residue.

[0052] The polyester resin may contain cyclohexanedimethanol residues in an amount of 50 mol% or more, 70 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, 95 mol% or more, or 98 mol% or more, where the total amount of the diol residues is 100 mol%. The diol residues may also contain 100 mol% or less of the cyclohexanedimethanol residues. That is, the diol residues may consist essentially of the cyclohexanedimethanol residues. When the cyclohexanedimethanol residues are used as the diol residues in the above amounts, a polyester resin with further improved heat resistance and hydrolysis resistance can be provided.

[0053] The diol residue may further include a diol residue other than a cyclohexanedimethanol residue, and the polyester resin may be a copolymer polyester resin.

[0054] Specific examples of additional diol residues may be the residue of ethylene glycol, 1,3-propanediol, 1,2-octanediol, 1,3-octanediol, 2,3-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,1-dimethyl-1,5-pentanediol, or mixtures thereof.

[0055] The dicarboxylic acid residues can include terephthalic acid residues and isophthalic acid residues.

[0056] Specifically, the dicarboxylic acid residue may be a residue of terephthalic acid, an isophthalic acid, or a mixture thereof.

[0057] The content of the terephthalic acid residues may be 90 mol% or more, 93 mol% or more, or 95 mol% or more, or may be less than 100 mol%, or 97 mol% or less, based on 100 mol% of the total dicarboxylic acid residues.

[0058] The content of the isophthalic acid residues may be more than 0 mol % when the total amount of the dicarboxylic acid residues is taken as 100 mol %, or may be 3 mol % or more, 10 mol % or less, 7 mol % or less, or 5 mol % or less.

[0059] Specifically, the content of the terephthalic acid residues may be 95 mol % or more when the total amount of the dicarboxylic acid residues is taken as 100 mol %, and the content of the isophthalic acid residues may be 5 mol % or less when the total amount of the dicarboxylic acid residues is taken as 100 mol %.

[0060] When the dicarboxylic acid residues contain terephthalic acid residues and isophthalic acid residues in the above amounts, the copolymer may have a relatively high melting point and low crystallization characteristics, and thus may have excellent heat resistance and processability at the same time.

[0061] The dicarboxylic acid residue may further include one or more selected from the group consisting of aromatic dicarboxylic acid residues such as dimethylterephthalic acid, naphthalenedicarboxylic acid, and orthophthalic acid; aliphatic dicarboxylic acid residues such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid; alicyclic dicarboxylic acid residues; and residues of esters thereof.

[0062] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 210°C, the flexible laminate 100 has a K HS The value is between 0.1 and 12.

[0063] [Formula 1-1] JPEG2026504305000005.jpg1156

[0064] In the formula 1-1, K HS is the variation index (% / °C) of the thermal shrinkage rate of the heat-resistant layer, T1 and T2 are the Celsius temperatures (°C) defined above, and HS T1 and H.S. T2 are the thermal shrinkage rates (%) of the heat-resistant layer before and after heat treatment at T1 and T2 for 10 minutes, respectively.

[0065] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 210°C, the variation index (K HS The value of ) may be 0.1 or more, 1 or more, or 3 or more, or may be 20 or less, 15 or less, or 11 or less.

[0066] K when T1 is a temperature between 230℃ and 245℃ and T2 is a temperature of 210℃ HS When the values ​​are within the above ranges, the heat shrinkage rate of the heat-resistant layer can be maintained low without significant change in a relatively high temperature range, and even when the heat-resistant layer is repeatedly used for a long period of time in a harsh environment such as a high temperature, deterioration in performance is substantially suppressed, thereby allowing the heat-resistant layer to maintain excellent performance.

[0067] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 190°C, the variation index (K HS The value of ) may be 0.1 or more, 1 or more, or 3 or more, or may be 18 or less, 15 or less, 10 or less, or 8 or less.

[0068] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 170°C, the variation index (K HS The value of ) may be 0.1 or more, 1 or more, or 2 or more, or may be 14 or less, 11 or less, 9 or less, or 6.3 or less.

[0069] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 150°C, the variation index (K HS The value of ) may be 0.1 or more, 1 or more, or 2 or more, or may be 10 or less, 7 or less, or 5 or less.

[0070] K when T1 is a temperature between 230°C and 245°C and T2 is a temperature between 150°C and 190°C HS When the value is within the above range, the heat shrinkage rate of the heat-resistant layer can be maintained low without significant change over a wide temperature range.

[0071] The heat-resistant layer 10 may have a heat shrinkage rate of 8% or less after being heat-treated at 245° C. for 10 minutes.

[0072] Specifically, the heat shrinkage rate of the heat-resistant layer 10 after heat treatment at 245°C for 10 minutes may be 8% or less, 6% or less, or 5% or less, or may be more than 0%, 1% or more, 3% or more, or 4% or more.

[0073] When the heat-resistant layer has the above-mentioned heat shrinkage rate after being heat-treated at 245°C for 10 minutes, the flexible laminate including the heat-resistant layer may not be substantially deformed even after being soldered at a high temperature.

[0074] The heat-resistant layer 10 may have a heat shrinkage rate of less than 5%, 3% or less, or 2.5% or less after being heat-treated at 230°C for 10 minutes, or may have a heat shrinkage rate of more than 0%, or 2% or more.

[0075] The heat-resistant layer 10 may have a heat shrinkage rate of less than 2.5%, 2% or less, or 1.6% or less after being heat-treated at 210°C for 10 minutes, or may have a heat shrinkage rate of more than 0%, or 1% or more.

[0076] The heat-resistant layer 10 may have a heat shrinkage rate of 1.5% or less, or 1% or less, after being heat-treated at 190°C for 10 minutes, or may be more than 0%, 0.5% or more, or 0.8% or more.

[0077] The heat-resistant layer 10 may have a heat shrinkage rate of 0.8% or less, 0.6% or less, or 0.5% or less after being heat-treated at 170°C for 10 minutes. The heat shrinkage rate may be more than 0%, or 0.4% or more.

[0078] When the heat-resistant layer has the above heat shrinkage value after being heat-treated at a temperature of 170°C to 230°C for 10 minutes, the heat-resistant layer may have excellent heat resistance in a relatively wide temperature range.

[0079] The heat-resistant layer 10 may have a heat shrinkage rate of 0.5% or less after being heat-treated at 150° C. for 30 minutes.

[0080] Specifically, the heat shrinkage rate of the heat-resistant layer 10 after heat treatment at 150° C. for 30 minutes may be 0.5% or less, 0.45% or less, or 0.4% or less, or may be more than 0%, 0.1% or more, or 0.3% or more.

[0081] When the heat-resistant layer has a heat shrinkage rate within the above range after being heat-treated at 150°C for 30 minutes, the warping phenomenon of the flexible laminate including the heat-resistant layer is substantially suppressed, and curl of 3 mm or more does not substantially occur in the flexible laminate.

[0082] The heat shrinkage rate of the heat-resistant layer 10 may be a heat shrinkage rate in one direction of the surface of the heat-resistant layer.

[0083] The heat shrinkage rate of the heat-resistant layer 10 may be the heat shrinkage rate in the machine direction (MD) or the cross direction (TD) of the heat-resistant layer.

[0084] Specifically, the heat shrinkage rate of the heat-resistant layer 10 may be the heat shrinkage rate in the machine direction (MD) of a sample obtained by cutting the heat-resistant layer into a size of 20 mm x 200 mm.

[0085] The heat shrinkage rate of the heat-resistant layer 10 may be a heat shrinkage rate in the machine direction (MD). When the heat shrinkage rate of the heat-resistant layer in the machine direction (MD) has the above-mentioned characteristics, it is possible to provide a heat-resistant layer that is excellent in workability and durability.

[0086] The thermal shrinkage value of the heat-resistant layer 10 is calculated by the following [Equation 2-1].

[0087] [Formula 2-1] Heat shrinkage rate (%) = 100 x (L0-L) / L0

[0088] In the formula 2-1, L0 is the length of the heat-resistant layer before the heat treatment, and L is the length of the heat-resistant layer after the heat treatment.

[0089] Specifically, in the formula 2-1, L0 may be the length in one direction of the surface of the heat-resistant layer before the heat treatment, and L may be the length in one direction of the surface of the heat-resistant layer after the heat treatment. In this case, when L0 is measured in the longitudinal direction (MD), L is also measured in the longitudinal direction, and when L0 is measured in the transverse direction (TD), L is also measured in the transverse direction. More specifically, in the formula 2-1, L0 may be the length in the longitudinal direction (MD) of a sample obtained by cutting the heat-resistant layer before the heat treatment into a size of 20 mm x 200 mm, and L may be the length in the longitudinal direction (MD) of the sample of the heat-resistant layer after the heat treatment.

[0090] The flexible laminate 100 has excellent dimensional stability.

[0091] The flexible laminate 100 has a dimensional change rate in the machine direction (MD) and the cross direction (TD) of 1% or less, as determined by the following formula 3.

[0092] [Formula 3] Dimensional change rate (%) = 100 x (L0'-L') / L0'

[0093] In the above formula 3, L0' is the length of the flexible laminate before heat treatment, and L' is the length of the flexible laminate after annealing, in which the flexible laminate is heat treated at 150°C for 30 minutes and then left at a temperature of 23°C to 25°C for 1 hour or more.

[0094] In the formula 3, L0' is the length in the longitudinal direction (MD) [or transverse direction (TD)] of the flexible laminate before heat treatment, and L' is the length in the longitudinal direction (MD) [or transverse direction (TD)] of the flexible laminate after annealing, which is achieved by heat treating the flexible laminate at 150°C for 30 minutes and then leaving it at a temperature of 23°C to 25°C for 1 hour or more.

[0095] The flexible laminate 100 is heat-treated at 150°C for 30 minutes, and then left at a temperature of 23°C to 25°C for 1 hour or more, and the dimensional change rate before and after annealing may be 1% or less, 0.5% or less, 0.1% or less, 0.05% or less, 0.01% or less, or 0.001% or less, or may be more than 0%.

[0096] The dimensional change rate of the flexible laminate 100 before and after the annealing may be 1% or less, 0.5% or less, 0.1% or less, 0.05% or less, 0.01% or less, or 0.001% or less in both the machine direction (MD) and the transverse direction (TD). It may also be more than 0%.

[0097] The dimensional change rate can be measured using a laminate sample prepared by cutting the flexible laminate into a square sample of 10 cm x 10 cm as a reference.

[0098] When the dimensional change rate of the flexible laminate before and after annealing is as described above, the degree of thermal expansion or contraction is maintained low even when the flexible laminate undergoes repeated heating and cooling processes, and the internal stress between layers can be controlled to be low even when the flexible laminate undergoes the above processes, thereby substantially preventing warpage such as curling in the flexible laminate.

[0099] The flexible laminate 100 may exhibit reduced curl or warpage.

[0100] The curl of the flexible laminate may be less than 3 mm. Specifically, the curl of the flexible laminate may be less than 3 mm, 2.5 mm or less, 2 mm or less, or 1 mm or less. It may also be more than 0.5 mm (see FIG. 3).

[0101] Curl refers to the phenomenon in which the flexible laminate warps due to internal stress applied to each layer, such as the difference in the degree of thermal expansion or thermal contraction between the layers of the flexible laminate, or the deformation of the layers due to the high temperature and pressure applied during the lamination process of the flexible laminate.

[0102] This curl phenomenon causes the flexible laminate to rise by that height, and when the flexible laminate is applied to a flexible copper clad laminate (FCCL) or a flexible printed circuit board (FPCB), problems may arise in workability and processability, such as making it difficult to form fine circuit patterns.

[0103] The degree of curl can be evaluated based on the curl value (CV; see FIG. 3), which is a value measured on one side (the surface in contact with the ground) of a sample cut into a square shape from the flexible laminate, to determine the degree to which a corner of the sample separates from the ground. Alternatively, the degree of curl can be evaluated by calculating the average value of the values ​​measured at each corner.

[0104] When the degree of curl of the flexible laminate is as described above, the degree of curl or warpage of the flexible laminate is controlled to be low, so that when it is applied to flexible copper clad laminates (FCCLs), flexible printed circuit boards (FPCBs), etc., defects such as cracks in the circuit can be prevented, and high-quality fine patterns can be formed, and processability during the production of FCCLs, FPCBs, etc. can also be improved.

[0105] The heat-resistant layer 10 may have a moisture absorption rate of 1% or less.

[0106] Specifically, the moisture absorption rate of the heat-resistant layer may be 1% or less, 0.7% or less, 0.4% or less, or 0.3% or less, or may be more than 0%, or 0.1% or more.

[0107] When the moisture absorption rate of the heat-resistant layer is within the above range, the penetration of moisture and the like can be suppressed even in a humid environment, and excellent properties can be maintained without deterioration of physical properties.

[0108] The moisture absorption rate of the heat-resistant layer is calculated by the following [Equation 4-1].

[0109] [Formula 4-1] Moisture absorption rate (%) = [(BA) / A] x 100

[0110] In the formula 4-1, A is the initial weight of the heat-resistant layer, and B is the weight of the heat-resistant layer after immersing it in water at room temperature for 24 hours and removing the surface moisture with tissue paper.

[0111] The thickness of the heat-resistant layer 10 may be 3000 μm or less, 2000 μm or less, 1000 μm or less, 500 μm or less, 250 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, or 60 μm or less. The thickness of the heat-resistant layer may be 1.5 μm or more, 10 μm or more, or 40 μm or more.

[0112] The conductive layer 20 includes an electrically conductive material. For example, the conductive layer may include one or more materials selected from the group consisting of electrically conductive metals such as copper, nickel, silver, gold, platinum, zinc, and tin, electrically conductive polymers, and mixtures thereof.

[0113] The conductive layer 20 may be formed by applying the material in the form of a wire or a thin film.

[0114] Specifically, the conductive layer 20 may be a copper foil containing copper (thin film copper foil).

[0115] Specifically, the conductive layer 20 may be a copper wire containing copper.

[0116] The thickness of the conductive layer 20 may be 6 μm or more, 10 μm or more, or 20 μm or more, and may be 200 μm or less, 150 μm or less, 100 μm or less, or 50 μm or less.

[0117] The conductive layer may be patterned.

[0118] The flexible laminate 100 may be a single-layer structure including a heat-resistant layer 10, 10' and a conductive layer 20 disposed on one side of the heat-resistant layer (see Figures 1(a) and (b)).

[0119] The flexible laminate 100 may have a double-layer structure including a heat-resistant layer 10 and conductive layers 20, 20' disposed on one side and the other side of the heat-resistant layer (see FIG. 1(c)).

[0120] Specifically, the flexible laminate 100 may be a flexible copper clad laminate (FCCL).

[0121] The flexible laminate 100 may include a conductive layer 20 and heat-resistant layers 10 disposed on one and the other sides of the conductive layer. The flexible laminate may appear as if the heat-resistant layers are not separated from each other and surround the conductive layer (not shown). In this case, the conductive layer may be wire-shaped.

[0122] Specifically, the flexible laminate 100 may be a flexible flat cable (FFC).

[0123] The flexible laminate 100 may further include adhesive layers 30, 30'.

[0124] The adhesive layers 30, 30' can be disposed between layers in the flexible laminate to improve the bonding strength between the layers. For example, the adhesive layers 30, 30' may be disposed between the heat-resistant layer and the conductive layer (see FIGS. 2(a) to 2(c)).

[0125] The adhesive layers 30 and 30' may include a thermosetting resin. Exemplarily, the thermosetting resin may be a polyester-based resin, an acrylic-based resin, an epoxy-based resin, or a mixture thereof. Exemplarily, the H-HCR series and HGB series manufactured by Hanwha may be used, but are not limited thereto.

[0126] The thickness of the adhesive layer 30, 30' may be 1 μm or more, 10 μm or more, or 20 μm or more, or may be 50 μm or less, or 40 μm or less.

[0127] The flexible laminate 100 has excellent heat resistance, dimensional stability, and warpage characteristics, and is therefore suitable for use in electrical and electronic device components such as flexible copper clad laminates (FCCLs), flexible printed circuit boards (FPCBs), and flexible flat cables (FCCs).

[0128] Polyester film 4 is a cross-sectional view of a polyester film according to one or more embodiments. The polyester film will now be described in detail with reference to FIG.

[0129] According to one embodiment, the polyester film 10" contains a cyclohexanedimethanol residue, a terephthalic acid residue, and an isophthalic acid residue. When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 210°C, the polyester film 10" has a K" according to the following formula 1-2: HS The value is between 0.1 and 12.

[0130] [Formula 1-2] JPEG2026504305000006.jpg1261

[0131] In the formula 1-2, K" HS is the coefficient of variation (% / °C) of the heat shrinkage of the polyester film, T1 and T2 are the Celsius temperatures (°C) defined above, and HS" T1 and HS" T2 are the heat shrinkage rates (%) of the polyester film before and after heat treatment at T1 and T2 for 10 minutes, respectively.

[0132] The polyester film 10" contains cyclohexanedimethanol residues, terephthalic acid residues, and isophthalic acid residues.

[0133] The polyester film 10 ″ is made of a polyester resin composition containing a polyester resin obtained by polymerizing a diol and a dicarboxylic acid, and the polyester film contains a diol residue and a dicarboxylic acid residue.

[0134] Detailed descriptions of the cyclohexanedimethanol residue, the terephthalic acid residue, the isophthalic acid residue, and the like are the same as those described above, and therefore will be omitted here.

[0135] The polyester resin may include both 1,4-cyclohexanedimethylene terephthalate and 1,4-cyclohexanedimethylene isophthalate residues as repeat units. The polyester resin may include poly(1,4-cyclohexylenedimethylene terephthalate-co-isophthalate) (PCTA) resin.

[0136] The polyester resin can have a weight average molecular weight (Mw) of 30,000 g / mol to 50,000 g / mol, or 30,000 g / mol to 40,000 g / mol.

[0137] For example, the polyester resin may be synthesized by mixing a monomer capable of forming a dicarboxylic acid residue and a monomer capable of forming a diol residue, followed by inducing an esterification reaction or a condensation reaction.

[0138] The polyester resin may be prepared by a conventional polymerization method, and a catalyst may be used to improve the efficiency of the polymerization reaction. For example, the polyester resin may be polymerized in the presence of a metal-containing catalyst such as titanium or antimony.

[0139] The catalyst may be applied in an amount of 1 to 1000 ppm, or 10 to 500 ppm, based on the weight of the polyester resin.

[0140] The catalyst may be a titanium-based compound, an antimony-based compound, a germanium-based compound, an aluminum-based compound, or a mixture thereof. Specifically, the catalyst may be a titanium-based compound. The titanium-based compound may include titanium tetraisopropoxide.

[0141] The synthesized polyester resin can be stored in the form of chips and subsequently utilized in the production of polyester films.

[0142] The stored polyester resin may be subjected to a drying process before film production, and the drying may be performed at a temperature of 150°C or less, or in an atmosphere of 70 to 148°C. Specifically, the drying may be performed in an atmosphere of 135 to 145°C. The drying may be performed so that the moisture content of the dried polyester resin is 100 ppm or less. Preferably, drying conditions are applied so that the moisture content is 50 ppm or less. If the drying process is performed at a temperature higher than 150°C, there is a risk of unintended color change occurring in the polyester resin itself.

[0143] The polyester resin composition may include a coating agent.

[0144] The binder can contribute to forming a film of uniform thickness without temperature gradient by adhering the extruded polyester resin composition sheet to a cooling casting roll. In addition, the binder can prevent excessive crystallization of the film during annealing, suppress uneven stretching, and prevent breakage.

[0145] The application agent may include a potassium-based metal salt and / or a magnesium-based metal salt. Specifically, the potassium-based metal salt may be potassium acetate (C2H3O2K), and the magnesium-based metal salt may be magnesium acetate (C4H6O4Mg).

[0146] The content of the coating agent contained in the polyester composition is based on the weight of the metal salt (including the ionized state; the same applies hereinafter) added.

[0147] The adhesive may be contained in an amount of 200 ppm or more, or 300 ppm or more, or 1000 ppm or less, or 600 ppm or less, based on the entire polyester resin composition.

[0148] The polyester resin composition may contain an antioxidant.

[0149] Antioxidants are typically used to suppress unintended side reactions in chemical reactions, primarily during the resin synthesis process. In some embodiments, antioxidants can be applied to resin compositions containing resins that have already been synthesized. This not only serves the basic function of suppressing side reactions during the film formation process, but also improves the oxidative stability and durability of the resulting film, thereby substantially preventing film aging even when exposed to harsh environments, such as repeated heating and cooling during use. These features make the polyester film highly applicable to components for electrical and electronic devices, such as flexible printed circuit boards (FPCBs) and flexible flat cables (FFCs).

[0150] The polyester resin composition may contain three or more antioxidants, specifically, a phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant.

[0151] The antioxidant may be contained in an amount of 100 ppm or more, 500 ppm or more, or 1000 ppm or more based on the total amount of the polyester resin composition, or 10000 ppm or less, 7000 ppm or less, or 5000 ppm or less.

[0152] The phenol-based antioxidant may be contained in an amount of 40 ppm to 3000 ppm based on the entire polyester resin composition. The phosphorus-based antioxidant may be contained in an amount of 40 ppm to 3000 ppm based on the entire polyester resin composition. The sulfur-based antioxidant may be contained in an amount of 40 ppm to 3000 ppm based on the entire polyester resin composition.

[0153] The weight ratio of the adhesive to the antioxidant may be 1:0.01 to 20. Specifically, the weight ratio of the adhesive to the antioxidant may be 1:2 to 15, 1:4 to 13, 1:7 to 11, or 1:8 to 10. When the weight ratio of the adhesive to the antioxidant is as described above, the mutual interaction is substantially suppressed, and the durability and optical properties of the film can be further improved while each function is sufficiently performed.

[0154] When T1 is a temperature of 230°C to 245°C and T2 is a temperature of 210°C, the polyester film 10" has a K" HS The value is between 0.1 and 12.

[0155] [Formula 1-2] JPEG2026504305000007.jpg1162

[0156] In the formula 1-2, K" HS is the coefficient of variation (% / °C) of the heat shrinkage of the polyester film, T1 and T2 are the Celsius temperatures (°C) defined above, and HS" T1 and HS" T2 are the heat shrinkage rates (%) of the polyester film before and after heat treatment at T1 and T2 for 10 minutes, respectively.

[0157] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 210°C, the coefficient of variation (K") of the heat shrinkage of the polyester film is HS The value of ) may be 0.1 or more, 1 or more, or 3 or more, or may be 20 or less, 15 or less, or 11 or less.

[0158] K" when T1 is a temperature between 230℃ and 245℃ and T2 is a temperature of 210℃ HSWhen the values ​​are within the above ranges, the heat shrinkage rate of the polyester film can be maintained low without significant change in a relatively high temperature range, and even when the polyester film is repeatedly used for a long period of time in a harsh environment such as a high temperature, deterioration in performance can be substantially suppressed and excellent performance can be maintained.

[0159] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 190°C, the coefficient of variation (K") of the heat shrinkage of the polyester film is HS The value of ) may be 0.1 or more, 1 or more, or 3 or more, or may be 18 or less, 15 or less, 10 or less, or 8 or less.

[0160] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 170°C, the coefficient of variation (K") of the heat shrinkage of the polyester film is HS The value of ) may be 0.1 or more, 1 or more, or 2 or more, or may be 14 or less, 11 or less, 9 or less, or 6.3 or less.

[0161] When T1 is a temperature between 230°C and 245°C and T2 is a temperature of 150°C, the coefficient of variation (K") of the heat shrinkage of the polyester film is HS The value of ) may be 0.1 or more, 1 or more, or 2 or more, or may be 10 or less, 7 or less, or 5 or less.

[0162] K" when T1 is a temperature between 230℃ and 245℃ and T2 is a temperature between 150℃ and 190℃ HS When the value is within the above range, the heat shrinkage of the polyester film can be maintained low without significant change over a wide temperature range.

[0163] The polyester film 10" may have a heat shrinkage rate of 8% or less after being heat-treated at 245°C for 10 minutes.

[0164] Specifically, the heat shrinkage rate of the polyester film 10" after heat treatment at 245°C for 10 minutes may be 8% or less, 6% or less, or 5% or less. Alternatively, the heat shrinkage rate may be more than 0%, 1% or more, 3% or more, or 4% or more.

[0165] When the polyester film 10″ has the above heat shrinkage value after heat treatment at 245° C. for 10 minutes, a flexible laminate including the polyester film may not be substantially deformed even after soldering at a high temperature.

[0166] The heat shrinkage rate of the polyester film 10" after heat treatment at 230°C for 10 minutes may be less than 5%, 3% or less, or 2.5% or less. Alternatively, the heat shrinkage rate may be more than 0%, or 2% or more.

[0167] The heat shrinkage rate of the polyester film 10" after heat treatment at 210°C for 10 minutes may be less than 2.5%, may be 2% or less, or may be 1.6% or less. Also, the heat shrinkage rate may be more than 0%, or may be 1% or more.

[0168] The heat shrinkage rate of the polyester film 10" after heat treatment at 190°C for 10 minutes may be 1.5% or less, or 1% or less. Alternatively, the heat shrinkage rate may be more than 0%, 0.5% or more, or 0.8% or more.

[0169] The heat shrinkage rate of the polyester film 10" after heat treatment at 170°C for 10 minutes may be 0.8% or less, 0.6% or less, or 0.5% or less. Alternatively, the heat shrinkage rate may be more than 0%, or 0.4% or more.

[0170] When the polyester film 10″ has the above heat shrinkage value after being heat-treated at a temperature of 170° C. to 230° C. for 10 minutes, the polyester film may have excellent heat resistance in a relatively wide temperature range.

[0171] The polyester film 10" may have a heat shrinkage rate of 0.5% or less after being heat-treated at 150°C for 30 minutes.

[0172] Specifically, the heat shrinkage rate of the polyester film 10" after heat treatment at 150°C for 30 minutes may be 0.5% or less, 0.45% or less, or 0.4% or less. Alternatively, the heat shrinkage rate may be greater than 0%, 0.1% or more, or 0.3% or more.

[0173] When the heat shrinkage rate of the polyester film 10" after heat treatment at 150°C for 30 minutes is within the above range, warping of a flexible laminate including the polyester film is substantially suppressed, and curl of 3 mm or more may not occur substantially in the flexible laminate.

[0174] The heat shrinkage of the polyester film 10 ″ may be a heat shrinkage in one direction on the surface of the polyester film.

[0175] The heat shrinkage rate of the polyester film 10" may be the heat shrinkage rate in the machine direction (MD) or the transverse direction (TD) of the polyester film.

[0176] Specifically, the heat shrinkage rate of the polyester film 10'' may be the heat shrinkage rate in the machine direction (MD) of a sample obtained by cutting the polyester film into a size of 20 mm x 200 mm.

[0177] The heat shrinkage rate of the polyester film 10" may be a heat shrinkage rate in the machine direction (MD). When the heat shrinkage rate of the polyester film in the machine direction (MD) has the above-mentioned characteristics, a heat-resistant layer having excellent workability and further excellent durability can be provided.

[0178] The heat shrinkage rate of the polyester film 10" is calculated by the following formula 2-2.

[0179] [Formula 2-2] Heat shrinkage rate (%) = 100 x (L"0 - L") / L"0

[0180] In the formula 2-2, L"0 is the length of the polyester film before the heat treatment, and L" is the length of the polyester film after the heat treatment.

[0181] Specifically, in the formula 2-2, L"0 may be the length in one direction of the surface of the polyester film before heat treatment, and L" may be the length in one direction of the surface of the polyester film after heat treatment. In this case, when L"0 is measured in the longitudinal direction (MD), L" is also measured in the longitudinal direction, and when L"0 is measured in the transverse direction (TD), L" is also measured in the transverse direction. More specifically, in the formula 2-2, L"0 may be the length in the longitudinal direction (MD) of a sample obtained by cutting the polyester film before heat treatment into a size of 20 mm x 200 mm, and L" may be the length in the longitudinal direction (MD) of the heat-treated polyester film sample.

[0182] The polyester film 10" may have a moisture absorption rate of 1% or less.

[0183] Specifically, the moisture absorption rate of the polyester film may be 1% or less, 0.5% or less, 0.3% or less, or 0.2% or less, or may be more than 0%, or 0.2% or more.

[0184] When the moisture absorption rate of the polyester film is within the above range, the film can suppress the penetration of moisture even in a humid environment, and can maintain excellent properties without any deterioration in physical properties.

[0185] The moisture absorption rate is calculated by the following [Equation 4-2].

[0186] [Formula 4-2] Moisture absorption rate (%)=(B"-A") / A"×100

[0187] In the formula 4-2, A" is the initial weight of the film, and B" is the weight of the film after immersing it in water at room temperature for 24 hours and removing the surface moisture with tissue paper.

[0188] The polyester film 10" may contain a coating agent or a reaction product thereof.

[0189] A detailed description of the applying agent will be omitted since it overlaps with the above description.

[0190] The polyester film 10" may contain an antioxidant or a reaction product thereof.

[0191] A detailed description of the antioxidant will be omitted here since it overlaps with the above description.

[0192] The thickness of the polyester film 10" may be 1 μm to 1,000 μm, or 10 μm to 500 μm. Specifically, the thickness of the polyester film may be 1,000 μm or less, 500 μm or less, 250 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, or 60 μm or less. Alternatively, the thickness may be 0.5 μm or more, 1 μm or more, 10 μm or more, or 40 μm or more.

[0193] When the polyester film 10" has the above thickness, the mechanical properties are maintained within a practically usable range.

[0194] In this specification, when physical properties whose values ​​vary depending on thickness are presented without any specific mention of thickness, the sample having a thickness of 50 μm is used as the reference.

[0195] The polyester film 10″ can be used as a heat-resistant layer disposed on at least one surface of the conductive layer or surrounding the conductive layer, and can maintain relatively stable physical properties for a long period of time even when exposed to repeated high heat generated by the conductive layer.

[0196] Specifically, the heat-resistant layer may include the polyester film.

[0197] Specifically, the heat-resistant layer may be the polyester film.

[0198] The method for producing the polyester film will now be described.

[0199] The method for producing the polyester film may include a sheet-forming step of extruding a polyester resin composition containing a polyester resin obtained by polymerizing a diol and a dicarboxylic acid to form a sheet, a stretching step of stretching the sheet in the longitudinal direction and the width direction, and a heat-setting step of heat-setting the stretched sheet.

[0200] The polyester resin contained in the polyester resin composition may be dried. The drying is performed before the extrusion step. The drying may be performed so that the moisture content of the polyester resin is 100 ppm or less, preferably 50 ppm or less. The drying temperature may be 150°C or less. Specifically, the drying temperature may be 135°C to 145°C. If the drying step is performed at a temperature higher than 150°C, there is a risk of unintended color change occurring in the polyester resin itself. The drying temperature is the ambient temperature during drying.

[0201] The extrusion may be carried out at a temperature of 230°C to 300°C, or 250°C to 290°C.

[0202] In the stretching step, the stretching is performed after preheating. The preheating may be performed within a range of Tg+5°C to Tg+50°C, or within a range of Tg+10°C to Tg+20°C, based on the glass transition temperature (Tg) of the polyester resin. For example, the preheating may be performed within a range of 70°C to 90°C. In this case, the flexibility required for stretching of the polyester film can be ensured, and the phenomenon of breakage during the stretching process can be suppressed.

[0203] In the stretching step, the stretching may be performed by biaxial stretching. For example, the film may be stretched in both the machine direction (longitudinal direction, MD) and the transverse direction (tenter direction, TD) by simultaneous biaxial stretching or sequential biaxial stretching. Preferably, the film may be stretched in one direction first, and then in the direction perpendicular to that direction by sequential biaxial stretching.

[0204] The machine direction (MD) stretch ratio for the polyester film may be greater than 2.9, greater than or equal to 3.0, or greater than or equal to 3.1, and may be less than or equal to 5.0, less than or equal to 4.5, less than or equal to 4, or less than or equal to 3.3.

[0205] The stretch ratio in the transverse direction (TD) of the polyester film may be 3.0 or more, 3.3 or more, 3.5 or more, or 3.7 or more, and may be 5.0 or less, 4.5 or less, 4.1 or less, or 3.9 or less.

[0206] The ratio (d1 / d2) of the stretch ratio (d1) in the transverse direction (TD) to the stretch ratio (d2) in the machine direction (MD) of the polyester film may be 0.9 to 1.4, or 1.1 to 1.3. The stretch ratios (d1, d2) represent the length after stretching, assuming that the length before stretching is 1.0.

[0207] When the stretch ratios in the machine direction (MD) and transverse direction (TD) of the polyester film and the ratio of the stretch ratios are within the above ranges, the mechanical properties of the film can be further improved.

[0208] In the stretching step, the stretching may be performed while applying heat at 700° C. to 800° C. using a far-infrared heater (Radiation Heater; R / H).

[0209] Specifically, the stretching can be carried out while applying heat of 730°C to 770°C using a far-infrared heater.

[0210] In the stretching step, the stretching speed may be 6.5 m / min to 8.5 m / min.

[0211] In the heat setting step, the stretched sheet can be heat set.

[0212] In the heat setting step, the heat setting temperature may be 150° C. to 300° C., 230° C. to 270° C., or 240° C. to 250° C. The heat setting may be performed for 5 seconds to 10 minutes, or 10 seconds to 7 minutes.

[0213] In the heat setting step, after the heat setting is started, the polyester film may be relaxed in the machine direction (MD) and the transverse direction (TD), and the temperature at this time may be in the range of 150°C to 250°C.

[0214] The relaxation rate in the machine direction (MD) of the polyester film may be greater than 0%, greater than 0.1%, or greater than 1%. It may also be less than 10%, less than 7%, less than 5%, less than 3%, or less than 2.2%. When such a relaxation rate in the machine direction is applied, a polyester film with a smaller shrinkage rate in the machine direction even at high temperatures can be provided.

[0215] The relaxation rate of the polyester film in the transverse direction (TD) may be more than 0%, 1% or more, or 3% or more, and may be 10% or less, 7% or less, or 5.5% or less.

[0216] The polyester film produced by the method for producing a polyester film has the above-mentioned physical properties, and thus can provide a film excellent in heat resistance, durability, moisture resistance, and the like.

[0217] flexible flat cable The flexible flat cable according to one embodiment includes the flexible laminate 100 or polyester film described above.

[0218] Specifically, the flexible flat cable may include one or more conductive layers 20 and a heat-resistant layer 10 disposed around at least a portion of the conductive layer.

[0219] The heat-resistant layer may include the polyester film described above.

[0220] The flexible flat cable may include a first heat-resistant layer, a conductive layer 20 disposed on the first heat-resistant layer, and a second heat-resistant layer disposed on the conductive layer. The flexible flat cable may appear as if the first heat-resistant layer and the second heat-resistant layer are substantially undivided and surround the conductive layer.

[0221] The first heat-resistant layer and the second heat-resistant layer may each include the polyester film described above. For example, the polyester film may be applied to a layer that directly contacts the conductive layer, but is not limited thereto.

[0222] Detailed descriptions of the flexible laminate, polyester film, heat-resistant layer, conductive layer, etc. are the same as those described above, and therefore will be omitted.

[0223] The flexible laminate and the polyester film have improved heat resistance and durability, making them suitable for use as a heat-resistant layer of a flexible flat cable that can be stably applied to major components such as automotive powertrains and engine control components, which are subject to relatively high temperatures.

[0224] flexible electronic board A flexible electronic substrate according to an embodiment includes the flexible laminate 100 or polyester film described above.

[0225] Specifically, the flexible electronic substrate may include a heat-resistant layer 10 and a conductive layer 20 or a conductive pattern layer disposed on at least one surface of the heat-resistant layer.

[0226] The heat-resistant layer may include the polyester film described above.

[0227] Detailed descriptions of the properties and structure of the flexible laminate are omitted because they overlap with the above-mentioned descriptions. Detailed descriptions of the composition and properties of the polyester film are omitted because they overlap with the above-mentioned descriptions. Detailed descriptions of the composition and properties of the heat-resistant layer are omitted because they overlap with the above-mentioned descriptions.

[0228] The conductive pattern layer may include one or more electrically conductive patterns formed by etching or punching the conductive layer.

[0229] The conductive pattern layer may include an electrically conductive material. For example, the conductive pattern layer may include one or more materials selected from the group consisting of electrically conductive metals such as copper, nickel, silver, gold, platinum, zinc, and tin, electrically conductive polymers, and mixtures thereof.

[0230] Specifically, the conductive pattern layer may include a copper pattern.

[0231] The shape of the pattern is not particularly limited, and may include, for example, a line pattern or a planar spiral pattern.

[0232] The conductive pattern layer may include a circuit pattern, and for example, the circuit pattern may include a printed circuit pattern. The circuit pattern may include a two-dimensional or three-dimensional pattern according to the design of the substrate.

[0233] The conductive pattern layer may include a terminal pattern, and the terminal pattern may be a pattern electrically connected to an external circuit.

[0234] The thickness of the conductive pattern layer may be 1 μm or more, 6 μm or more, 10 μm or more, or 20 μm or more, or may be 200 μm or less, 150 μm or less, 100 μm or less, or 50 μm or less.

[0235] The flexible electronic substrate may further include an adhesive layer.

[0236] The adhesive layer may be disposed between layers of the flexible electronic substrate to improve adhesion between the layers. Exemplarily, the adhesive layer may be disposed between the heat-resistant layer and the conductive pattern layer.

[0237] Detailed descriptions of examples of the adhesive layer, thickness, etc. are the same as those described above, and therefore will be omitted here.

[0238] The present invention will be described in more detail with reference to the following specific examples. The following examples are merely illustrative examples to aid in understanding the present invention, and are not intended to limit the scope of the present invention.

[0239] Manufacture of polyester film (heat-resistant layer) and evaluation of its physical properties 1) Production of polyester resins and resin compositions A monomer mixture containing 100 mol% 1,4-cyclohexanedimethanol (CHDM) as a diol and 95 mol% terephthalic acid (TPA) and 5 mol% isophthalic acid (IPA) as dicarboxylic acids was added to a mixer. 0.001 parts by weight of titanium (Ti) catalyst (based on 100 parts by weight of the monomer mixture) was added and transesterification was carried out at 275°C. The reactant was transferred to a separate reactor equipped with a vacuum system and polymerized at 285°C for 160 minutes to obtain polycyclohexylene dimethylene terephthalate (PCT) resin. The resin was dried at 140°C and then used in subsequent processes. The PCT resin thus prepared was used as the polyester resin in the following Examples 1 and 2, and Comparative Examples 1-3.

[0240] Thereafter, a coating agent and an antioxidant were added to the polyester resin as follows to prepare a polyester resin composition.

[0241] As the adhesive, potassium acetate (C2H3O2K) and magnesium acetate (C4H6O4Mg) were mixed in a weight ratio of 1:9, and added in an amount of 400 ppm based on the total amount of the polyester resin composition.

[0242] The antioxidants were a mixture of a phenolic antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant, and were added at 2500 ppm based on the total amount of the polyester resin composition. The phenolic antioxidant was Irganox 1010 from BASF at 1000 ppm. The phosphorus-based antioxidant was Doverphos S9228 from Dover at 500 ppm. The sulfur-based antioxidant was AO-412S from Adeka at 1000 ppm.

[0243] 2) Production of polyester film (heat-resistant layer) Example 1 A polyester resin composition having the composition shown in Table 1 below was charged into an extruder. The polyester resin composition was extruded at approximately 290°C and cast at approximately 20°C using a casting roll to form a sheet. The sheet was preheated and then stretched in the machine direction (MD) and transverse direction (TD) while being heated to 750°C using a far-infrared heater (R / H). The stretched sheet was then heat-set for approximately 30 seconds and relaxed to produce each polyester film. The stretch ratio, heat-setting temperature, relaxation rate, etc. are shown in Table 1 below.

[0244] Example 2 and Comparative Examples 1 to 3 Other conditions were the same as in Example 1, but the polyester films of Example 2 and Comparative Examples 1 to 3 were produced using the draw ratio, heat setting temperature, relaxation rate, etc. shown in Table 1.

[0245] The polyester films thus produced were used as heat-resistant layers in Examples 1 and 2 and Comparative Examples 1 to 3, respectively.

[0246] [Table 1]

[0247] 3) Evaluation of the physical properties of the heat-resistant layer Heat shrinkage rate and K HS Value evaluation The heat-resistant layers of Examples 1 and 2 and Comparative Examples 1 to 3 were cut so that one edge was perpendicular to the machine direction (MD) (width direction) and the other edge was parallel to the machine direction (MD) (longitudinal direction) to produce 20 mm x 200 mm heat-resistant layer samples.

[0248] The heat-resistant layer sample was heat-treated in an oven at 150° C. with circulating air for 30 minutes, and then taken out again, and the change in length in the machine direction (MD) was measured at room temperature.

[0249] Using the measured change in length, the thermal shrinkage rate of the heat-resistant layer in the machine direction (MD) at 150°C to 245°C was calculated according to the following [Equation 2-1], and is shown in Table 2 below.

[0250] [Formula 2-1] Heat shrinkage rate (%) = 100 x (L0-L) / L0

[0251] In the formula 2-1, L0 is the length of the heat-resistant layer before the heat treatment, and L is the length of the heat-resistant layer after the heat treatment.

[0252] The heat shrinkage of the film at a temperature of 170° C. or higher was measured in the same manner as described above, except that the film sample was heat-treated for 10 minutes, and the results are shown in Table 2 below.

[0253] Using the measured values ​​of the heat shrinkage, the heat shrinkage variation index (K HS ) values ​​were measured and are shown in Table 3 below.

[0254] [Formula 1-1] JPEG2026504305000009.jpg1154

[0255] In the formula 1-1, K HS is the variation index (% / ℃) of the thermal shrinkage rate of the heat-resistant layer, T1 and T2 are the temperatures (℃) shown in the table, and HS T1 and H.S. T2 are the thermal shrinkage rates (%) in one direction of the heat-resistant layer when heat-treated at T1 and T2 for 10 minutes, respectively.

[0256] [Table 2]

[0257] [Table 3]

[0258] Moisture resistance evaluation The moisture absorption rate of the produced film was measured in accordance with ASTM D570 to evaluate its moisture resistance. First, a 50 μm thick film was cut into a 70 mm diameter circle to prepare a sample. The film sample was dried in a hot air oven at 50°C for 24 hours or more, then turned off and cooled to room temperature. The initial weight (A) of the film sample was measured using a precision balance. The film sample was then immersed in water at room temperature for 24 hours, and the surface moisture was removed with tissue paper, after which the weight (B) was measured. Based on this, the moisture absorption rate was calculated using the following [Equation 4-2] and is shown in Table 4 below.

[0259] [Formula 4-2] Moisture absorption rate (%)=[(B"-A") / A"]×100

[0260] In the above formula 3, A" is the initial weight of the film, and B" is the weight of the film after immersing it in water at room temperature for 24 hours and removing the surface moisture with tissue paper.

[0261] [Table 4]

[0262] Referring to Tables 1 to 3, the heat shrinkage values ​​of Examples 1 and 2 were lower than those of Comparative Examples 1 to 3 over a wide high temperature range of 150°C to 245°C. In addition, the variation index (K HS ) values ​​were also lower than those of Comparative Examples 1 to 3 in a wide high temperature range of 170°C to 245°C, especially in the range of 230°C to 245°C, and therefore it was found that the films of Examples 1 and 2 had excellent heat resistance.

[0263] Referring to Table 4, it can be seen that the films of Examples 1 and 2 have low moisture absorption rates of 0.2% or less and relatively excellent moisture resistance.

[0264] Manufacturing of flexible laminates and evaluation of their properties 1) Manufacturing of flexible laminates The polyester film produced was used as a heat-resistant layer, and a 36 μm thick copper foil produced by SKNX was used as a conductive layer, and an adhesive layer (HGB-E250WG produced by Hanwha) was placed between the insulating sheet and the conductive sheet.

[0265] The assembly, in which the conductive layer, adhesive layer, and heat-resistant layer are arranged in that order, is subjected to a press at 150°C for 1 hour with a surface pressure of 20 kgf / cm. 2 After that, the laminate was cured. Through this process, flexible laminates each having a conductive layer, an adhesive layer, and a heat-resistant layer arranged in this order were manufactured.

[0266] 2) Evaluation of the physical properties of the heat-resistant layer and the soft laminate 1) Evaluation of dimensional stability The manufactured flexible laminate was cut so that one edge was parallel to the machine direction (MD) (longitudinal direction) and the other edge was perpendicular to the machine direction (MD) (transverse direction), and the machine direction (MD) and transverse direction (TD) lengths of the flexible laminate were measured on a 10 cm x 10 cm square laminate sample.

[0267] The sample was then heat-treated in an oven at 150°C (±2°C) for 30 minutes and then left at room temperature (23°C to 25°C) for at least 1 hour. After annealing, the lengths of the flexible laminate in the machine direction (MD) and transverse direction (TD) were measured again, and the dimensional change rate before and after annealing was evaluated using the following [Equation 3].

[0268] [Formula 3] Dimensional change rate (%) = 100 x (L0'-L') / L0'

[0269] In the formula 3, L0' is the length of the flexible laminate before heat treatment, and L' is the length after annealing, in which the flexible laminate is heat treated at 150°C for 30 minutes and then left at a temperature of 23°C to 25°C for 1 hour or more.

[0270] The dimensional change rates of the flexible laminate in the machine direction (MD) and transverse direction (TD) were measured, and the results were shown in Table 5 below, with pass if it was 0.1% or less and fail if it exceeded 0.1%.

[0271] 2) Curl evaluation (warping evaluation) The manufactured flexible laminate was cut into an A4 size (width: 210 mm, length: 297 mm) laminate sample, and the curl was evaluated.

[0272] The height at which each corner of the sample was separated from the ground was measured, and the average value was taken as the curl value.

[0273] The curl value was evaluated as ◯ when it was less than 3 mm, Δ when it was 3 mm or more but less than 5 mm, and × when it was 5 mm or more. The results are shown in Table 5 below.

[0274] [Table 5]

[0275] Referring to Table 5, in the case of Examples 1 and 2, the change rate before and after annealing was 0.1% or less in both the machine direction (MD) and the cross direction (TD), indicating that the flexible laminate had excellent dimensional stability.

[0276] Furthermore, referring to Table 5, it was found that in the flexible laminates using the films of Examples 1 and 2 as the heat-resistant layer, the degree of curl was 3 mm or less, and the degree of warpage was low.

[0277] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the appended claims also fall within the scope of the present invention. [Explanation of symbols]

[0278] 10,10' heat resistant layer 20,20' conductive layer 30,30' adhesive layer 100 Flexible laminate 10" polyester film CV Curl Value

Claims

1. a heat-resistant layer and a conductive layer disposed on at least one surface of the heat-resistant layer; the heat-resistant layer contains a cyclohexanedimethanol residue, a terephthalic acid residue, and an isophthalic acid residue; T １ is a temperature between 230°C and 245°C, and T ２ When the temperature is 210°C, K according to the following equation 1-1 ＨＳ A flexible laminate having a value of 0.1 or more and 12 or less. [Formula 1-1] (In the above formula 1-1, K ＨＳ is the variation index (% / °C) of the thermal shrinkage rate of the heat-resistant layer, and T １ and T ２ are the temperatures in degrees Celsius (°C) as defined above, and HS Ｔ１ and H.S. Ｔ２ are the T １ and T ２ The heat shrinkage rate (%) of the heat-resistant layer when heat-treated at 100°C for 10 minutes.

2. 2. The flexible laminate according to claim 1, wherein the heat-resistant layer has a heat shrinkage rate of 8% or less when heat-treated at 245°C for 10 minutes.

3. 2. The flexible laminate according to claim 1, wherein the heat-resistant layer has a heat shrinkage rate of 0.5% or less when heat-treated at 150°C for 30 minutes.

4. 2. The flexible laminate according to claim 1, wherein the dimensional change rate according to the following formula 3 is 1% or less. [Formula 3] Dimensional change rate (%) = 100 × (L ０ '-L') / L ０ ' (In the formula 3, the L ０ L' is the length of the flexible laminate before the flexible laminate is heat-treated, and L' is the length of the flexible laminate after the flexible laminate is annealed, and the annealing is performed by heat-treating the flexible laminate at 150°C for 30 minutes and then leaving it at a temperature of 23°C to 25°C for 1 hour or more.

5. 4. The flexible laminate of claim 3, wherein the flexible laminate after being heat-treated at 150°C for 30 minutes has a curl of less than 3 mm.

6. containing cyclohexanedimethanol residues, terephthalic acid residues, and isophthalic acid residues; T １ is a temperature between 230°C and 245°C, and T ２ When the temperature is 210°C, K" according to the following equation 1-2 ＨＳ A polyester film having a value of 0.1 or more and 12 or less. [Formula 1-2] (In the above formula 1-2, K" ＨＳ is the variation index (% / °C) of the heat shrinkage rate of the polyester film, and T １ and T ２ are the degrees Celsius (°C) as defined above, and HS" Ｔ１ and HS" Ｔ２ are the T １ and T ２ The heat shrinkage rate (%) of the polyester film when heat-treated at 100°C for 10 minutes.

7. 7. The polyester film according to claim 6, which has a moisture absorption rate of 1% or less.

8. A flexible flat cable comprising the flexible laminate of claim 1.

9. A flexible flat cable comprising the polyester film of claim 6.

10. A flexible electronic substrate comprising the flexible laminate of claim 1.

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