KR20230142981A - Flexible metal laminate film and preperation mehtod of the same - Google Patents

Abstract

The flexible metal laminate film according to example embodiments includes a core layer including a liquid crystal polymer, and a metal layer disposed on the core layer. When measuring the melting peak temperature of the core layer twice using a differential scanning calorimeter, the deviation of the melting peak temperature when measured twice relative to the melting peak temperature when measured once is 6°C or less. Accordingly, a flexible metal laminate film having excellent dielectric properties, adhesion, and high temperature durability can be provided.

Description

Flexible metal laminated film and manufacturing method thereof {FLEXIBLE METAL LAMINATE FILM AND PREPERATION MEHTOD OF THE SAME}

The present invention relates to a flexible metal laminated film and a method of manufacturing the same. More specifically, it relates to a flexible metal laminated film including a resin layer and a metal layer and a method of manufacturing the same.

Recently, as high-frequency or ultra-high-frequency antennas are employed in image display devices, antenna radiation characteristics can be easily disturbed by dielectric properties around the antenna. For example, if the dielectric constant of the flexible printed circuit board (FPCB) connected to the antenna increases, dielectric loss or signal loss of the antenna may occur, and the impedance characteristics of the set antenna may be disturbed.

For example, the flexible metal laminated film can be used as a substrate for flexible printed circuit boards (FPCB), and can also be used for cotton heating element electromagnetic wave shielding materials, flat cables, packaging materials, etc. The flexible metal laminated film may be composed of a core layer and a metal layer, and a polyimide layer may be used as the core layer.

Recently, high-frequency or ultra-high frequency band communication is being performed in bands such as 4G or 5G, and therefore, low dielectric properties are required for substrates on which various electronic components are mounted. For example, when a substrate or substrate with high dielectric properties is used in an electronic device, it may be difficult to increase the transmission rate, and the signal loss rate may increase due to the high transmission rate.

Additionally, as flexible displays that can be folded or curved have recently been developed, substrates or substrates applied to image display devices also need to be designed to have improved flexibility and bendability. However, for substrates with low dielectric constant and dielectric loss, durability and mechanical properties may be reduced under harsh conditions.

For example, Republic of Korea Patent Publication No. 10-2013-0027442 discloses a flexible metal laminate including a polyimide layer and a metal layer laminated on the polyimide layer, but does not consider the dielectric properties described above. not.

Korean Patent Publication No. 10-2013-0027442

One object of the present invention is to provide a flexible metal laminate film with improved dielectric properties and durability.

One object of the present invention is to provide a flexible circuit board to which the above-described flexible metal laminated film is applied.

One object of the present invention is to provide a method for manufacturing the above-described flexible metal laminated film.

1. Core layer containing liquid crystal polymer (LCP); And a metal layer disposed on the core layer,

When measuring the melting peak temperature of the core layer twice using a differential scanning calorimeter (DSC), the deviation of the melting peak temperature (T ₂ ) when measured twice relative to the melting peak temperature (T ₁ ) when measured once A flexible metal laminated film having a temperature of 6° C. or lower.

2. In 1 above, the melting peak temperature is a value measured at a temperature increase rate of 10°C/min at a temperature of 30°C to 400°C using a differential scanning calorimeter.

3. In 1 above, the deviation of the melting peak temperature (T ₂ ) when measured twice with respect to the melting peak temperature (T ₁ ) when measured once of the core layer is 3°C to 6°C. Metal laminated film.

4. The flexible metal laminated film of 1 above, wherein the adhesive force of the core layer to the metal layer at 85°C is 0.8 kN/m or more.

5. The flexible metal laminated film according to 1 above, wherein the adhesive force of the core layer to the metal layer at 25°C is 0.85 kN/m or more.

6. The flexible metal laminated film of 1 above, wherein the liquid crystal polymer has a melting point of 290°C to 300°C.

7. The flexible metal laminated film of 1 above, wherein the core layer has a thickness of 5㎛ to 100㎛, and the metal layer has a thickness of 5㎛ to 18㎛.

8. Bonding a metal layer to one side of a preliminary core layer containing liquid crystal polymer (LCP); and

A method of producing a flexible metal laminated film, comprising converting the preliminary core layer into a core layer by heat treating the bonded core layer and the metal layer at a temperature of 290°C to 310°C for 3 to 6 hours.

9. The method of manufacturing a flexible metal laminated film according to item 8 above, wherein the heat treatment step is performed at a temperature of 290°C to 295°C.

10. The method of 8 above, wherein the step of bonding the metal layer to one surface of the preliminary core layer includes disposing the metal layer on the one surface of the preliminary core layer; and pressurizing the metal layer at a pressure of 1 MPa to 10 MPa and a vacuum degree of 0.05 kPa to 0.5 kPa.

11. The method of manufacturing a flexible metal laminated film according to item 10 above, wherein the step of pressurizing the metal layer is performed at a temperature of 200°C to 300°C for 30 minutes to 2 hours.

12. The method of manufacturing a flexible metal laminated film according to item 8 above, wherein the heat treatment step is performed using a convection oven.

13. Flexible circuit board, manufactured from the flexible metal laminated film according to 1 above.

14. The flexible circuit board according to 13 above, including a wiring layer formed from the metal layer.

15. The method of 14 above, wherein the wiring layer is disposed on the upper surface of the core layer,

A flexible circuit board further comprising a ground layer disposed on the bottom of the core layer and overlapping the wiring layer in the thickness direction.

The flexible metal laminate film according to example embodiments includes a core layer and a metal layer disposed on the core layer. The core layer includes liquid crystal polymer. Accordingly, the core layer may have a low dielectric constant and dielectric loss tangent. Additionally, signal reduction and power supply loss can be prevented when driving at high frequencies or ultra-high frequencies, and antenna gain and radiation characteristics can be improved.

Additionally, when measuring the melting peak temperature of the core layer twice, the deviation between the melting peak temperature measured when the temperature was raised once and the melting peak temperature measured when the temperature was raised twice may be 6°C or less. Accordingly, the orientation of the liquid crystal polymer included in the core layer may be lowered, and the core layer may have isotropic characteristics, thereby improving the adhesion of the core layer to the metal layer.

Additionally, the adhesion of the core layer to the metal layer at 85°C may be below a predetermined value. In this case, the structural stability of the flexible metal laminated film can be excellent even when used/stored for a long period of time under harsh conditions of high temperature and high humidity.

The flexible metal laminated film according to exemplary embodiments may be formed by bonding a core layer and a metal layer and then heat treating the core layer and the metal layer at a predetermined temperature for a predetermined time. Accordingly, the liquid crystal polymer may have an isotropic structure, and the adhesion and bonding force between the core layer and the metal layer may increase, thereby suppressing peeling and fracture of the flexible metal laminated film.

1 is a schematic cross-sectional view showing a flexible metal laminate film according to example embodiments.
2 is a schematic cross-sectional view showing a flexible metal laminate film according to example embodiments.
3 is a schematic cross-sectional view showing a flexible circuit board according to example embodiments.

The flexible metal laminated film according to embodiments of the present invention includes a core layer containing liquid crystal polymer (LCP), and a metal layer disposed on the core layer. When measuring the melting peak temperature of the core layer twice using a differential scanning calorimeter, the deviation of the melting peak temperature when measured twice relative to the melting peak temperature when measured once is 6°C or less.

With reference to the drawings below, embodiments of the present invention will be described in more detail. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention along with the contents of the above-described invention, so the present invention is described in such drawings. It should not be interpreted as limited to the specifics.

The terms “first”, “second”, “one end”, “other end”, “top”, “bottom”, “top”, “bottom”, “top”, “bottom”, etc. used in this application are absolute. It does not limit the position or order, but is used in a relative sense to distinguish different components or parts.

<Flexible metal laminated film>

1 is a schematic plan view showing a flexible metal laminate film according to example embodiments.

Referring to FIG. 1, the flexible metal laminated film may include a core layer 110 and a metal layer 120 laminated on at least one surface of the core layer 110.

The core layer 110 may include liquid crystal polymer (LCP). Liquid crystal polymers have a low permittivity or low dissipation factor, so they can provide high signal efficiency in high frequency or ultra-high frequency bands. For example, as the core layer 110 includes a liquid crystal polymer, the overall dielectric constant and dielectric coefficient of the core layer 110 may be lowered.

In this case, the core layer 110 may have a low dielectric loss tangent (dielectric loss or loss tangent; Df) value, and improved signal characteristics may be provided without signal loss or reduction even at high signal transmission speeds. Therefore, when applied to an antenna structure, a flexible circuit board with improved signal transmission characteristics can be provided while maintaining high-frequency/ultra-high-frequency antenna radiation reliability.

In some embodiments, the liquid crystal polymer may include liquid crystal polyester. For example, the liquid crystal polymer may include liquid crystalline polyesteramide, liquid crystalline polyester ether, liquid crystalline polyester carbonate, liquid crystalline polyesterimide, etc.

In one embodiment, the liquid crystalline polyester may be formed using an aromatic compound as a monomer. For example, the liquid crystalline polyester may be a liquid crystalline wholly aromatic polyester.

According to exemplary embodiments, when measuring the melting peak temperature of the core layer 110 twice using a differential scanning calorimeter, the melting peak temperature (T ₁ ) measured once is measured twice. The deviation of the melting peak temperature (T ₂ ) during measurement may be 6°C or less.

In one embodiment, the melting peak temperature (T ₁ ) at the initial temperature increase of the core layer 110 is measured, and then the temperature lowering and temperature raising process is performed once more to obtain the melting peak temperature (T ₂ ) at the second temperature increase. It can be measured. In this case, the difference between the melting peak temperature (T ₁ ) at the initial temperature increase and the melting peak temperature (T ₂ ) at the second temperature increase may be 6°C or less.

For example, the melting peak temperature (T ₁ ) can be measured once by heating the core layer 110 containing the liquid crystal polymer at a temperature increase rate of 10°C/min in the temperature range of 30°C to 400°C. Afterwards, the melting peak temperature (T ₂ ) can be measured twice by lowering the temperature to 30°C at a temperature drop rate of -10°C/min and raising the temperature at a temperature increase rate of 10°C/min in the temperature range of 30°C to 400°C. there is.

Within the melting peak temperature deviation range, the crystallinity of the liquid crystal polymer may be low and the core layer 110 may have low orientation. Therefore, due to the isotropic core layer 110, the adhesion between the core layer 110 and the surface layer (eg, metal layer) can be increased, and peeling and fracture of the flexible metal laminate film can be prevented.

For example, liquid crystal polymers have an inherent anisotropy characteristic in which molecules are oriented in a specific direction, so separation can occur between a skin layer with a relatively high orientation and a central layer with a relatively low orientation. . Additionally, due to its anisotropic properties, it may have low adhesive strength and toughness, and may have a poor appearance.

As the core layer 110 according to exemplary embodiments has the above-described melting peak temperature difference, the molecules included in the core layer 110 may have a low degree of orientation. Therefore, since the liquid crystal polymer contained in the core layer 110 has isotropic characteristics, the core layer 110 can have high bonding strength, and the mechanical properties such as toughness and the appearance characteristics of the liquid crystal polymer can be improved. You can. In addition, the difference in orientation between the surface layer and the central layer is reduced, thereby suppressing the occurrence of peeling, and the adhesion and adhesion of the core layer 110 to the metal layer 120 can be increased.

In some embodiments, the deviation of the melting peak temperature (T ₂ ) when measured twice relative to the melting peak temperature (T ₁ ) when measured once of the core layer 110 may be 3°C to 6°C. and, more specifically, may be 5°C to 6°C.

Within the above range, the crystallinity of the liquid crystal polymer can be lowered, and isotropic properties can be further improved as the crystals are oriented in one direction. Accordingly, the crystallinity of the center and surface layers of the liquid crystal polymer can be made uniform, and peeling between the center and surface layers can be suppressed, thereby improving the bonding force and adhesion of the core layer 110 to the metal layer 120.

In some embodiments, the thickness of the core layer 110 may be 5㎛ to 100㎛, or more accurately, 25㎛ to 50㎛.

When the thickness of the core layer 110 is less than 5㎛, the transmission loss rate in the high frequency or ultra-high frequency region may increase as the thickness of the core layer 110, which is an insulating layer, becomes thinner. When the thickness of the core layer 110 exceeds 100㎛, as the thickness of the flexible metal laminated film increases, it may be difficult to thin it, and bending and bending characteristics may deteriorate.

In some embodiments, the melting point of the liquid crystal polymer may be 290°C to 300°C, and preferably 290°C to 295°C.

Within the above range, the orientation and crystallinity of the liquid crystal polymer may be lowered by the heat treatment process, and the liquid crystal polymer may have overall isotropy. In addition, shrinkage, wrinkles, and fracture of the core layer 110 due to the high-temperature heat treatment process can be prevented, and dimensional stability and processability can be excellent.

The metal layer 120 may be disposed on at least one side of the core layer 110. For example, after bonding the metal layer 120 to one side of the preliminary core layer, the preliminary core layer and the metal layer 120 may be heat treated to form a laminated film of the core layer 110 and the metal layer 120.

In some embodiments, the step of bonding the metal layer 120 to the preliminary metal layer includes forming a laminate by laminating the metal layer 120 on one surface of the preliminary core layer, and using a vacuum press to form the metal layer of the laminate. It may include the step of pressurizing (120).

The bonding pressure of the metal layer 120 and the preliminary core layer may be 1 MPa to 10 MPa. If the bonding pressure is less than 1 MPa, sufficient pressure may not be applied to the preliminary core layer and the metal layer 120, and adhesion may be reduced. If the bonding pressure exceeds 10 MPa, cracks may occur inside the core layer 110 due to excessive pressure, and mechanical properties may deteriorate.

In one embodiment, the step of pressurizing the laminate may be performed at a degree of vacuum of 0.05 kPa to 0.5 kPa. For example, the metal layer 120 can be attached to the preliminary core layer by pressing it at a pressure of 1 MPa to 10 MPa and a vacuum degree of 0.05 kPa to 0.5 kPa using a vacuum press machine.

In some embodiments, the step of bonding the metal layer 120 may be performed under heat treatment. For example, the preliminary core layer and the metal layer 120 may be bonded by heat fusion.

Heat fusion can be done using a heat roll, double belt press, heating plate, or a combination of these.

In one embodiment, the bonding temperature of the metal layer 120 may be 200°C to 300°C. If the joining temperature is less than 200°C, the anchoring effect with the metal layer 120 may be reduced due to low melting of the surface of the preliminary core layer. If the joining temperature exceeds 300°C, melting of the preliminary core layer may intensify and an overflow phenomenon may occur.

In one embodiment, the bonding time may be 30 minutes to 2 hours. Within the above range, sufficient pressurization is performed on the preliminary core layer and the metal layer 120, so that adhesion can be excellent and productivity reduction due to an increase in process time can be prevented.

In one embodiment, the flexible metal laminated film may further include an adhesive layer or an adhesive layer between the core layer 110 and the metal layer 120 to bond the core layer 110 and the metal layer 120.

The metal layer 120 is made of silver (Ag), gold (Au), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), chromium (Cr), titanium (Ti), and tungsten (W). , niobium (Nb), tantalum (Ta), vanadium (V), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), tin (Sn), or alloys thereof. It can be included.

In one embodiment, the metal layer 120 may include copper. For example, the metal layer 120 may be a copper thin film.

In some embodiments, the thickness of the metal layer 120 may be 5㎛ to 18㎛. When the thickness of the metal layer 120 is less than 5㎛, as the resistance of the metal layer 120 increases, a heat generation problem in the flexible metal laminated film may occur. When the thickness of the metal layer 120 is more than 18㎛, the radius of curvature of the flexible metal laminated film may increase and the flexibility may decrease.

According to exemplary embodiments, the metal layer 120 may be bonded to the preliminary core layer and then the laminated film may be heat treated. In this case, the preliminary core layer may be converted into the core layer 110. For example, through the heat treatment step, the crystallinity and orientation of the preliminary core layer are lowered, and the core layer 110 may have isotropic characteristics.

In some embodiments, the heat treatment step may be performed at a temperature of 290°C to 310°C.

If the heat treatment temperature is less than 290°C, the liquid crystal polymer may become anisotropic and the arrangement direction of the crystals may become irregular. Accordingly, the difference in the melting peak temperature between the first and second rounds of liquid crystal polymer may increase, and the adhesion between the core layer 110 and the metal layer 120 may decrease.

If the heat treatment temperature exceeds 310°C, the liquid crystal polymer may melt during the heat treatment process and bubbles may be generated within the core layer 110, and peeling and fracture between the core layer 110 and the metal layer 120 may occur. there is.

Preferably, the heat treatment temperature may be 290°C to 300°C, and more preferably 290°C to 295°C. Within the above range, the liquid crystal polymer can be isotropic, and the surface uniformity and thickness uniformity of the core layer 110 can be improved by preventing melting and collapse of the core layer 110 due to the heat treatment process.

The heat treatment step may be performed for 180 to 360 minutes. If the heat treatment time is less than 180 minutes, the adhesion between the core layer 110 and the metal layer 120 may decrease, and the orientation of the core layer 110 may increase. If the heat treatment time exceeds 360 minutes, random bubbles may be generated within the core layer 110, which may lower mechanical properties and reduce productivity.

The heat treatment step may be performed using a convection oven. For example, the laminated film in which the core layer 110 and the metal layer 120 are bonded may be attached to a substrate, for example, a SUS plate, and then heat-treated at a temperature of 290°C to 310°C using a hot air oven. .

As the laminate in which the preliminary core layer and the metal layer 120 are bonded is heat treated, the liquid crystal polymer included in the core layer 110 may have the above-described deviation in melting peak temperature.

For example, when the liquid crystal polymer is heat treated at the above-mentioned heat treatment temperature and time, as the crystallinity and orientation of the core layer 110 decreases, delamination between the core layer 110 and the metal layer 120 can be suppressed. . Therefore, the flexible metal laminated film can have excellent heat resistance and high temperature adhesion.

According to exemplary embodiments, the adhesion of the core layer 110 to the metal layer 120 at 85°C may be 0.8 kN/m or more. For example, the adhesion may be a value measured after storing the flexible metal laminate film at a temperature of 85° C. and a relative humidity of 85% for 192 hours.

For example, the adhesion at 85°C can be measured based on a 90° peel test according to IPC-TM 650 using an autograph (AG-1S, manufactured by SHIMADZU). Specifically, the adhesion of the core layer 110 to the metal layer 120 at 85°C is determined by a peeling angle of 90° and a thickness of 50.8 mm after storing the flexible metal laminate film at a temperature of 85°C and a relative humidity of 85% for 192 hours. It may be a 90° peel strength measured by peeling the metal layer 120 from the core layer 110 at a peeling speed of /min.

In one embodiment, the adhesion force of the core layer 110 to the metal layer 120 at 85°C may be 0.8 kN/m to 1.0 kN/m. Within the above range, structural deformation such as delamination and shrinkage between the core layer 110 and the metal layer 120 can be suppressed even under severe conditions of high temperature and high humidity, and a flexible circuit board with a stable laminated structure can be provided.

According to exemplary embodiments, the adhesion force of the core layer 110 to the metal layer 120 at room temperature (25°C) may be 0.85 kN/m or more, for example, 0.85 kN/m to 1.1 kN. It could be /m.

As the room temperature adhesion between the core layer 110 and the metal layer 120 satisfies the above range, the structural durability of the flexible metal laminated film can be further improved.

For example, the adhesion of the core layer 110 to the metal layer 120 at room temperature can be measured after storing the flexible metal laminated film for 24 hours at room temperature (25°C) and 50% relative humidity. there is. Specifically, the adhesion at room temperature was measured by peeling the metal layer 120 from the core layer 110 using an autograph (AG-1S, manufactured by SHIMADZU) under the conditions of a peeling angle of 90° and a peeling speed of 50.8 mm/min. It can be as high as 90° peel strength.

2 is a schematic cross-sectional view showing a flexible metal laminate film according to example embodiments.

Referring to FIG. 2, a metal layer may be disposed on both sides of the core layer 110. For example, the flexible metal laminate film includes a core layer 110, a first metal layer 120 disposed on the top surface of the core layer 110, and a second metal layer 120 disposed on the bottom surface of the core layer 110. It may include a metal layer 130.

In one embodiment, the second metal layer 130 may overlap the first metal layer 120 in the thickness direction. For example, the first metal layer 120 may be provided as a circuit or conductor pattern, and the second metal layer 130 may be provided as a ground layer.

As the second metal layer 130 is arranged to overlap the first metal layer 120 in the thickness direction with the core layer 110 in between, the capacitance and inductance between the first metal layer 120 and the second metal layer 130 can be formed. Therefore, even at high transmission speeds, power supply and signal loss rates can be reduced, and signal transmission and reception efficiency can be increased.

<Flexible circuit board>

3 is a schematic cross-sectional view showing a flexible circuit board according to example embodiments.

Referring to FIG. 3, a flexible circuit board can be manufactured from the flexible metal laminated film described above. For example, the flexible circuit board may include a core layer 210 and a wiring layer 220 disposed on one surface of the core layer.

The metal layer of the flexible metal laminate film may be provided as the wiring layer 220. For example, the wiring layer 220 can be formed by patterning the metal layer.

The core layer 210 may include liquid crystal polymer. When the core layer 210 measures the melting peak temperature twice using a differential scanning calorimeter, the deviation of the melting peak temperature (T ₂ ) when measured twice relative to the melting peak temperature (T ₁ ) when measured once It may be 6℃ or lower.

The wiring layer 220 may be disposed on the bottom of the core layer. In one embodiment, the flexible circuit board may be electrically connected to the antenna 300 through a wiring layer 220. For example, the wiring layer 220 may be provided as a wiring that distributes power from a driving integrated circuit (IC) chip to the antenna 300.

The antenna 300 includes an antenna dielectric layer 310, an antenna electrode layer 320 disposed on the top surface of the antenna dielectric layer 310, and an antenna ground layer 330 disposed on the bottom surface of the antenna dielectric layer 310. can do.

The antenna dielectric layer 310 may include, for example, a transparent resin material that has the flexibility to be folded. For example, the antenna dielectric layer 310 is made of polyester resin such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; Cellulose-based resins such as diacetylcellulose and triacetylcellulose; polycarbonate-based resin; Acrylic resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate; Styrene-based resins such as polystyrene and acrylonitrile-styrene copolymer; Polyolefin resins such as polyethylene, polypropylene, polyolefins with cyclo- or norbornene structures, and ethylene-propylene copolymers; Vinyl chloride-based resin; Amide resins such as nylon and aromatic polyamide; imide-based resin; polyethersulfone-based resin; Sulfone-based resin; polyetheretherketone-based resin; Sulfated polyphenylene-based resin; Vinyl alcohol-based resin; Vinylidene chloride-based resin; Vinyl butyral resin; Allylate resin; polyoxymethylene-based resin; It may include thermoplastic resins such as epoxy resins. These may be used alone or in combination of two or more.

In some embodiments, the antenna dielectric layer 310 is made of an adhesive film such as an optically clear adhesive (OCA), an optically clear resin (OCR), silicon oxide, silicon nitride, silicon oxynitride, etc. It may also contain the same inorganic insulating material.

The antenna electrode layer 310 may include a radiation electrode of the antenna 300, a transmission line electrically connected to the radiation electrode, and a signal pad. The radiation electrode can transmit and receive radiation signals. The transmission line or signal pad may be electrically connected to the wiring layer 220.

The antenna electrode layer 320 and the antenna ground layer 330 are made of silver (Ag), gold (Au), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), chromium (Cr), and titanium ( Ti), tungsten (W), niobium (Nb), tantalum (Ta), vanadium (V), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), tin ( Sn) or alloys thereof may be included. These may be used alone or in combination of two or more. For example, silver (Ag) or a silver alloy (eg, silver-palladium-copper (APC) alloy) may be used to implement low resistance.

In one embodiment, the wiring layer 220 may be electrically connected to the antenna electrode layer 320 through a conductive intermediate structure 260. The conductive intermediate structure 260 may be formed of, for example, an anisotropic conductive film (ACF).

In some embodiments, an upper coverlay film 250 and a lower coverlay film 240 for protecting wiring may be formed on the upper and lower surfaces of the core layer 210, respectively.

According to exemplary embodiments, a ground layer 230 may be disposed on the upper surface of the core layer 210. The ground layer 230 may be arranged to overlap the wiring layer 220 in the thickness direction with the core layer 210 interposed therebetween.

The ground layer 230 may have a line shape or a plate shape. The ground layer 230 may function as a barrier that shields or suppresses noise or self-radiation generated from the wiring layer 220.

In some embodiments, a driving IC chip 270 may be disposed on a flexible circuit board.

For example, the driver IC chip 270 is disposed on the lower part of the flexible circuit board and may be electrically connected to the wiring layer 220. Power may be supplied from the driving IC chip 270 to the antenna 300 through the wiring layer 220.

Hereinafter, experimental examples including preferred examples and comparative examples are presented to aid understanding of the present invention. However, these examples are only illustrative of the present invention and do not limit the scope of the appended claims, and do not limit the scope of the present invention. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and technical spirit, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

Examples and Comparative Examples

Example 1

A 12-μm-thick copper foil substrate (made by Solus Advanced Materials, Rz: 0.45 μm) was laminated on a 50 μm-thick liquid crystal polymer (Chiyoda, Tm: 293°C) film. Afterwards, the laminate was put into a vacuum press machine (Model-KVHC, manufactured by Kitagawa Seiki), and then pressed for 60 minutes under the conditions of a temperature of 250°C, a pressure of 1.5 MPa, and a vacuum degree of 0.1 kPa to form a single-sided flexible metal laminate. Manufactured.

The prepared single-sided flexible metal laminate was attached to a Sus-plate and placed in a hot air oven (Model-IPHH-202, manufactured by Espec). Afterwards, the flexible metal laminated film of Example 1 was manufactured by heat treatment for 180 minutes in a nitrogen atmosphere and a temperature of 290°C.

Example 2

A single-sided flexible metal laminate was manufactured in the same manner as in Example 1.

The prepared cross-sectional flexible metal laminate was attached to a Sus-plate and placed in a hot air oven. Afterwards, the flexible metal laminated film of Example 2 was manufactured by heat treatment for 180 minutes in a nitrogen atmosphere and a temperature of 295°C.

Example 3

A single-sided flexible metal laminate was manufactured in the same manner as in Example 1.

The prepared cross-sectional flexible metal laminate was attached to a Sus-plate and placed in a hot air oven. Afterwards, the flexible metal laminated film of Example 3 was manufactured by heat treatment for 360 minutes in a nitrogen atmosphere and a temperature of 295°C.

Example 4

A single-sided flexible metal laminate was manufactured in the same manner as in Example 1.

The prepared cross-sectional flexible metal laminate was attached to a Sus-plate and placed in a hot air oven. Afterwards, the flexible metal laminated film of Example 4 was manufactured by heat treatment for 180 minutes in a nitrogen atmosphere and a temperature of 310°C.

Example 5

A single-sided flexible metal laminate was manufactured in the same manner as in Example 1.

The prepared cross-sectional flexible metal laminate was attached to a Sus-plate and placed in a hot air oven. Afterwards, the flexible metal laminated film of Example 5 was manufactured by heat treatment for 360 minutes in a nitrogen atmosphere and a temperature of 300°C.

Comparative Example 1

A single-sided flexible metal laminate was manufactured in the same manner as in Example 1. The heat treatment step for the flexible metal laminate was omitted to prepare a non-heat treated flexible metal laminate film.

Comparative Example 2

A single-sided flexible metal laminate was manufactured in the same manner as in Example 1.

The prepared cross-sectional flexible metal laminate was attached to a Sus-plate and placed in a hot air oven. Afterwards, the flexible metal laminated film of Comparative Example 2 was manufactured by heat treatment for 180 minutes in a nitrogen atmosphere and a temperature of 280°C.

Comparative Example 3

A single-sided flexible metal laminate was manufactured in the same manner as in Example 1.

The prepared cross-sectional flexible metal laminate was attached to a Sus-plate and placed in a hot air oven. Afterwards, the flexible metal laminated film of Comparative Example 3 was manufactured by heat treatment for 120 minutes in a nitrogen atmosphere and a temperature of 295°C.

Comparative Example 4

A single-sided flexible metal laminate was manufactured in the same manner as in Example 1.

The prepared cross-sectional flexible metal laminate was attached to a Sus-plate and placed in a hot air oven. Afterwards, the flexible metal laminated film of Comparative Example 4 was manufactured by heat treatment for 180 minutes in a nitrogen atmosphere and a temperature of 320°C.

Melting peak temperature deviation measurement

A specimen was prepared by cutting the flexible metal laminated film according to Examples and Comparative Examples to a width of 15.7 mm and a length of 50 mm. Using differential scanning calorimetry (DSC), the melting peak temperature of the core layer was measured. Specifically, the melting peak temperature was measured once by increasing the temperature in the temperature range of 30°C to 400°C at a temperature increase rate of 10°C/min. After measuring the melting peak temperature once, the temperature was lowered to 30°C at a cooling rate of -10°C/min. Afterwards, the temperature was again raised in the temperature range of 30°C to 400°C at a temperature increase rate of 10°C/min, and the melting peak temperature was measured twice.

The melting peak temperature deviation of the core layer was calculated by calculating the difference between the measured first melting peak temperature and the second melting peak temperature.

Experiment example

(1) Evaluation of core layer appearance

After etching the copper foil substrate of the flexible metal laminated film according to Examples and Comparative Examples, the appearance of the core layer was evaluated by observing it with an optical microscope (100x magnification). At this time, etching of the copper foil substrate was carried out by diluting 200 g of non-toxic etching powder (SME Trading Company) in 1 L of water and heating to prepare an etching solution, and then precipitating the flexible metal laminated film in the prepared etching solution.

The evaluation criteria are as follows.

<Evaluation criteria>

○: No bubbles larger than 50㎛ in diameter were observed on the surface of the core layer.

×: Observation of bubbles with a diameter of 50㎛ or more on the surface of the core layer

(2) Room temperature adhesion evaluation

A specimen was prepared by cutting the flexible metal laminated film according to Examples and Comparative Examples to a width of 15.7 mm and a length of 50 mm. The prepared specimen was stored for 24 hours at a temperature of 25°C and a relative humidity of 50%. Afterwards, the adhesion between the core layer and the copper foil substrate was measured using an autograph (AG-1S, Shimadzu) under the conditions of a peeling angle of 90° and a peeling speed of 50.8 mm/min.

(3) High temperature adhesion evaluation

A specimen was prepared by cutting the flexible metal laminated film according to Examples and Comparative Examples to a width of 15.7 mm and a length of 50 mm. The prepared specimen was stored for 192 hours at a temperature of 85°C and relative humidity of 85%. Afterwards, the adhesion between the core layer and the copper foil substrate was measured using an autograph (AG-1S, Shimadzu) under the conditions of a peeling angle of 90° and a peeling speed of 50.8 mm/min.

division Example 1 Example 2 Example 3 Example 4 Example 5 Melting peak temperature deviation (℃) 5.4 5.2 5.8 5.8 5.9 Appearance evaluation ○ ○ ○ × ○ Room temperature adhesion (kN/m) 0.86 0.87 0.85 0.89 0.84 High temperature adhesion (kN/m) 0.82 0.84 0.82 0.85 0.81

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Melting peak temperature deviation (℃) 9.7 7.8 8.1 6.5 Appearance evaluation ○ ○ ○ × Room temperature adhesion (kN/m) 0.31 0.36 0.34 0.58 High temperature adhesion (kN/m) 0.23 0.29 0.27 0.50

Referring to Tables 1 and 2, in the case of examples in which the heat treatment process was performed within a predetermined temperature and time range, the deviation of the melting peak temperature when measured twice relative to the melting peak temperature when measured once of the core layer It can be confirmed that satisfies 6℃ or less.

In addition, it can be confirmed that the flexible metal laminated films of the examples have both high room temperature adhesion and high temperature adhesion as the deviation of the melting peak temperature satisfies the above-mentioned range. Accordingly, delamination between the core layer and the metal layer can be prevented, thereby improving the structural stability of the flexible metal laminated film.

In Example 4, in which heat treatment was performed at a relatively high temperature, it was confirmed that bubbles were generated in the core layer as melting of the liquid crystal polymer occurred.

It can be seen that the flexible metal laminated film according to the comparative examples had a melting peak temperature deviation of more than 6°C when the temperature was raised once and twice, and the room temperature adhesion and high temperature adhesion were reduced. Therefore, when the deviation of the melting peak temperature exceeds 6°C, it can be confirmed that peeling of the core and surface layers occurs as the core layer has high crystallinity and orientation and has anisotropic characteristics.

110, 210: core layer 120: metal layer, first metal layer
130: second metal layer 200: flexible circuit board
220: wiring layer 230: ground layer
240: lower coverlay film 250: upper coverlay film
260: Conductive intermediate structure 270: Driving IC chip
300: Antenna 310: Antenna dielectric layer
320: Antenna electrode layer 330: Antenna ground layer

Claims (15)

A core layer containing liquid crystal polymer (LCP); and
It includes a metal layer disposed on the core layer,
When measuring the melting peak temperature of the core layer twice using a differential scanning calorimeter (DSC), the deviation of the melting peak temperature (T ₂ ) when measured twice relative to the melting peak temperature (T ₁ ) when measured once A flexible metal laminated film having a temperature of 6° C. or lower.
The method according to claim 1, wherein the melting peak temperature is a value measured at a temperature increase rate of 10°C/min at a temperature of 30°C to 400°C using a differential scanning calorimeter.
The method of claim 1, wherein the deviation of the melting peak temperature (T ₂ ) when measured twice relative to the melting peak temperature (T ₁ ) when measured once of the core layer is 3°C to 6°C. film.
The flexible metal laminated film according to claim 1, wherein the core layer has an adhesion force at 85° C. to the metal layer of 0.8 kN/m or more.
The flexible metal laminated film according to claim 1, wherein the core layer has an adhesion force of the metal layer at 25° C. of 0.85 kN/m or more.
The flexible metal laminate film according to claim 1, wherein the liquid crystal polymer has a melting point of 290°C to 300°C.
The flexible metal laminated film according to claim 1, wherein the core layer has a thickness of 5 ㎛ to 100 ㎛, and the metal layer has a thickness of 5 ㎛ to 18 ㎛.
Bonding a metal layer to one surface of a preliminary core layer containing liquid crystal polymer (LCP); and
A method of producing a flexible metal laminated film, comprising converting the preliminary core layer into a core layer by heat treating the bonded preliminary core layer and the metal layer at a temperature of 290°C to 310°C for 3 to 6 hours.
The method of claim 8, wherein the heat treatment step is performed at a temperature of 290°C to 295°C.
The method according to claim 8, wherein the step of bonding a metal layer to one surface of the preliminary core layer includes,
disposing the metal layer on the one surface of the preliminary core layer; and
A method of producing a flexible metal laminated film, comprising pressurizing the metal layer at a pressure of 1 MPa to 10 MPa and a vacuum degree of 0.05 kPa to 0.5 kPa.
The method of claim 10, wherein the step of pressurizing the metal layer is performed at a temperature of 200°C to 300°C for 30 minutes to 2 hours.
The method of claim 8, wherein the heat treatment step is performed using a convection oven.
A flexible circuit board made from the flexible metal laminated film according to claim 1.
The flexible circuit board of claim 13, comprising a wiring layer formed from the metal layer.
The method of claim 14, wherein the wiring layer is disposed on the bottom of the core layer,
A flexible circuit board further comprising a ground layer disposed on the upper surface of the core layer and overlapping the wiring layer in a thickness direction.