KR20110072763A - Refractive coverlay film and the preparing process thereof - Google Patents

Abstract

PURPOSE: A reflective coverlay film and a manufacturing method thereof are provided to improve the reflection efficiency of a light source by laminating an adhesive layer and a release layer member on the surface of an insulation base film. CONSTITUTION: A metal deposition layer is formed on one side of a base film. The metal deposition layer is formed with a vacuum deposition method and has an optical density over 0.6. A coating layer is coated on the metal deposition layer to protect the metal deposition layer. An adhesive and a protection member are successively formed on the other side of the base film.

Description

Reflective coverlay film and manufacturing method thereof

The present invention relates to a reflective coverlay film having a reflective layer function and a method of manufacturing the same, and more particularly, a metal deposition layer having a high reflectance and a low total light transmittance on one surface of an insulating base film, a resin coating layer protecting the deposited layer, and its The back cover layer has an adhesive layer and a protective base to show high reflectance and shielding properties, thereby increasing the brightness of the backlight, and eliminating complicated ink printing steps, thereby reducing the defect rate and reducing manufacturing time and manpower. A film and its manufacturing method are related.

In recent years, with the development of technology, the trend of miniaturization, thinning, high density, and high bending of electronic products is accelerating. Therefore, printed circuit board (PCB), which is easy to embed in narrow spaces, has been accelerated. The necessity has increased, and according to the demands of the market, a flexible printed circuit board (FPCB) has been developed that is capable of miniaturization, high density, and repeatability.

In order to manufacture such a flexible printed circuit board, a dry film on a flexible copper clad laminate (FCCL) in which a copper foil layer is formed on both surfaces or one end surface of an insulating base film such as polyimde having high heat resistance and high flexibility. After laminating), the circuit pattern is sequentially formed by exposure, development, and etching, and then a coverlay film is welded to the outside and bonded using a hot press. Various methods of manufacturing flexible printed circuit boards are disclosed. For example, Korean Patent Application No. 2003-0017707 relates to a method for manufacturing a multi-layer flexible printed circuit board. First, the inner layer circuit is formed through the coverlay film bonding process, and then bonded together with the interlayer adhesive sheet at once. A method of simplifying a manufacturing process by selectively electroplating using a layer and a dry film lamination process, an exposure process, a plating process, a soft etching process, and the like is disclosed. Korean Patent Application No. 2005-0003765 discloses a multilayered flexible Coverlay laminating method and apparatus for printed boards. In the process of manufacturing flexible printed circuit boards, coverlays are applied to copper foil circuit boards in which circuit patterns are formed through exposure, development, etching, and peeling processes using a roll-to-roll method using copper foil. In the temporary welding, a loading step of loading the copper foil circuit board and the coverlay of the roll state to each coiler having a different height; A laminating step of bringing the copper foil circuit board and the coverlay conveyed from the coilers at a constant speed into close contact with each other through a high temperature hot roller; A tension maintaining step of maintaining a constant tension in the path transferred to the close state; A horizontal alignment maintaining step of controlling to maintain a horizontal state of the copper foil substrate in which the coverlay is in close contact on the transfer path; A cutting step of cutting a substrate to a predetermined size by recognizing a sensing mark of a copper foil circuit board transferred while the horizontal state is maintained with a camera; Disclosed is a coverlay laminating method of a multilayer flexible printed circuit board comprising an unloading step of sequentially vacuuming the coverlay temporary circuit board on which the cutting is made.

As described above, in the configuration of the flexible printed circuit board, the coverlay film forming one layer of the flexible printed circuit board functions to protect and insulate the circuit pattern formed on the copper foil layer, to prevent oxidation, and to provide high flexibility. Films are generally processed according to the shape of the circuit pattern, followed by temporary welding, thermocompression bonding, plating processes for mounting devices such as LEDs, and mounting devices such as LEDs on the surface (SMT process), and then through the mold. It will go through the punching process (mounting and inspection shipment stage) for processing.

On the other hand, the backlight unit has a function of irradiating light to the liquid crystal display panel, and is used as a necessity to serve as a light source in a notebook, a mobile device, etc. The light source of the backlight mainly used in the past was a cold cathode fluorescent lamp (CCFL) Recently, LED lamps having an effect of increasing power consumption efficiency and lifespan, and at the same time increasing the quality of light sources have been adopted. As a result, the conventional CCFL is designed to provide a reflection function that increases the efficiency of the lamp by connecting the power supply to both edges of the linear lamp and placing the reflective film on one side of the linear lamp. Flexible printed circuit boards (FPCBs) are used, and thus, in order for LED-type light sources to increase reflection efficiency, the surface reflectance of flexible printed circuit boards is required to be high.

Therefore, in order to increase the reflectance of the surface of the flexible circuit board to meet such a requirement, it is conventionally required to apply a separate ink layer to the surface of the coverlay film layer that is the surface of the FPCB, a representative example of the ink layer Photo solder resist (PSR) or IR (IR) ink is widely used, the ink coating method is applied to a variety of known methods such as silk screen printing method, nylon screen method, metal screen method, polyester screen method, By applying ink to the entire surface of the polyimide film layer except for the portion where the LED component of the flexible printed circuit board is mounted, the ink can be made to increase the efficiency of the backlight unit having higher luminance when provided in the backlight unit. do.

However, in the conventional ink printing process as described above, the efficiency is mostly made by manual work, and also problems such as accuracy, appearance defects, uniformity, and surface cracking occur easily through various steps for coating and curing. However, it is difficult to control the occurrence of such defects, there is a problem that the uniformity is lowered, the appearance quality is worsened, the yield is lowered. In addition, since the process is performed in the final finished product state of the flexible printed circuit board, the economic damage in case of a defect can be said to be very large, and a solution for this has been urgently required, but the solution has not been suggested at all. to be.

As described above, in the prior art, the coverlay film is attached to the flexible printed circuit board for the backlight unit, and then, a method of providing a function of reflecting the light generated from the light emitting chip through a multi-step ink printing process in a later step is taken. Due to this, it is recognized that there are disadvantages of increased manufacturing cost, time, and defective rate when applying the multi-step ink printing process, and economic disadvantages when defects occur when the printing process is performed in the final finished state of the flexible printed circuit board. Accordingly, the present invention is to solve the above conventional problems as the first object. Specifically, it prevents an increase in process manufacturing cost, time, and defective rate due to performing a multi-step ink printing process after attaching a coverlay film to a flexible printed circuit board for a backlight unit, and furthermore, improves accuracy, uniformity, and appearance in the printing process. It is an object of the present invention to provide a reflective coverlay film in which defects hardly occur by making it easy to control.

Another object of the present invention is to provide a reflective coverlay film which can increase the efficiency of a backlight light source by providing a coverlay film having a higher level of reflectance than a coverlay film using white ink printing.

Another object of the present invention is to provide a manufacturing method that can more easily produce a coverlay film having the above characteristics.

The present invention may also be directed to achieving these and other objects which can be readily derived by those of ordinary skill in the art from the general description herein.

The object of the present invention described above is to provide a cover layer film having a metal deposition layer and the deposition layer protective layer according to the following specific configuration, giving a high reflection effect on the light source without the ink printing process in the flexible printed circuit board manufacturing process It could be achieved by providing a coverlay film having the effect of being a backlight unit to realize excellent brightness.

Reflective coverlay film of the present invention for achieving the above object;

A metal deposition layer having an average reflectance of 60% or more and a total light transmittance of 30% or less is formed on one surface of the base film, and a coating layer for protecting the deposition layer is coated on the top of the deposition layer, and vice versa. It characterized in that the protective substrate which is an adhesive and a release layer formed on the surface sequentially.

According to another configuration of the present invention, the metal deposition layer is a vacuum deposition method (vaccum deposition method) by using a vacuum deposition method (vaccum deposition method) by depositing a metal oxide containing a metal or SiOx or Al ₂ Ox on the surface of the base film to more than 0.6 optical It is characterized in that it is formed to have an optical density.

According to another configuration of the present invention, the coating layer for protecting the metal deposition layer is formed by coating a polymer resin containing at least one selected from acrylic, polyester, epoxy resin, urethane resin on the metal deposition layer It is characterized by.

Method for producing a reflective coverlay film of the present invention for achieving the above another object;

Forming a metal deposition layer on one surface of an insulating base film such as a polyimide film, a polyester film, an aramid film, and then coating the polymer resin protective layer;

After applying the flame-retardant adhesive on the back surface formed with the metal deposition layer and the protective layer is characterized in that consisting of the step of performing a release layer substrate and lamination on the adhesive coating surface.

Flexible printed circuit board comprising a reflective coverlay film of the present invention for achieving the above another object;

A metal deposition layer having an average reflectance of 60% or more and a total light transmittance of 30% or less and a resin coating layer protecting the deposition layer are formed on one surface of the base film, and an adhesive and a protective release layer are sequentially formed on the opposite side thereof. After removing the protective release layer of the formed reflective coverlay film, the adhesive surface is made by adhering to the circuit surface of the copper clad laminate (CCL) having a circuit pattern formed.

Reflective coverlay film of the present invention configured as described above is prepared by performing a lamination with the adhesive layer and the release layer substrate on the back surface of the insulating substrate film, the metal deposition layer and the deposition protection coating layer having a constant reflectance and total light transmittance, the back surface Therefore, the backlight unit can be manufactured with high reflectivity and high shielding properties and excellent appearance quality and uniformity without the ink printing process of the conventional flexible printed circuit board manufacturing process, thereby increasing the reflection efficiency of the light source and thus realizing excellent brightness. Not only can be used as a coverlay film for the present invention, but also excellent heat resistance and chemical resistance provides a coverlay film that can be used in a flexible printed circuit board manufacturing process.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail by preferable embodiment. However, the following examples are only presented by way of example only to more specifically describe the present invention, and do not represent all of the technical spirit of the present invention, various equivalents that may be substituted for them at the time of the present application It will be appreciated that there may be water and variations.

According to a preferred embodiment of the present invention, the reflective coverlay film is formed such that a flame-retardant adhesive is formed on one surface of the insulating plastic substrate, and the release treatment surface of the protective substrate having a release layer for protecting the adhesive surface is brought into contact with the adhesive. On the opposite side of the insulating plastic substrate, a metal deposition layer and a resin coating layer for protecting the metal deposition layer are formed.

At this time, as said insulating film, the film which consists of plastics, such as a polyimide, polyester naphthalate, polyester, polyphenylene sulfate, polyester sulfone, polyethyl ketone, aramid, polycarbonate, polyarylate, is mentioned. As for the thickness of the said insulating film, 5-200 micrometers is preferable. Moreover, surface treatment, such as hydrolysis, corona discharge, low temperature plasma, a physical surface asperity processing, and an easily-adhesive coating process, may be performed as needed. The thickness of the insulating film is most preferably used in the range of 10 to 125㎛.

According to a preferred embodiment of the present invention, the adhesive layer is a portion which is directly contacted with the circuit surface through a press, and serves to surround the circuit through a suitable flow of adhesive in the pressing process. Such an adhesive includes a thermosetting resin having a crosslinkable functional group (e.g., epoxy or acrylic) so as to be cured through crosslinking between molecules after pressing, and also a thermoplastic resin capable of controlling flowability. Acrylonitrile-butadiene copolymer (NBR) and the like. In addition, a bromine-based flame retardant or a phosphorous-based flame retardant may be included in order to have a level of flame retardancy to be satisfied as an electronic component, and mechanical properties or flame retardancy may be improved by including organic or inorganic particles. The thickness of the flame-retardant adhesive layer is preferably applied in accordance with the use within the range of 5 to 50㎛ according to the thickness of the circuit pattern formed from the copper clad laminate.

The peelable protective substrate attached on the adhesive layer according to the present invention should be one capable of peeling off the form of the adhesive layer without damage, for example, a polyester film subjected to a coating treatment of silicon or a fluorine compound ), A polyolefin-based film, and a paper laminated therewith, and one kind can be selected and used according to the purpose of use.

In addition, the thickness of the preferable peelable protective base material is 12.5-150 micrometers. If it is smaller than the above range, the handleability worsens, and if it is thicker than the above range, the cost increases.

According to the present invention, the material of the metal deposition film formed on the back surface of the adhesive layer and serving as a reflective layer is not particularly limited, but may be a metal such as Al, Cu, Sn, In, Zn, or two or more metal mixtures selected from the metals. Or an alloy may be used. As the vapor-deposited film of metal oxide material it is not particularly limited, and may take advantage of a _{SiO x, Al 2 O x,} InO x, SnO x , such as a metal oxide, or a second compound or a mixture of one metal oxide or more and the like. As the material of the metal deposition layer according to the present invention, aluminum oxide is most preferred.

The thickness of the metal deposition layer may be an appropriate thickness according to the required characteristics of the film, and considering the flexible characteristics of the deposited film, the thickness is preferably 0.006 µm to 1 µm. In addition, in order to be able to serve as a reflective layer, the preferred optical density should be 0.6 or more, and more preferably 0.9 or more. When the optical density of the metal deposition layer is lower than 0.6, the total light transmittance is increased by 50% or more, and thus there is a problem in that shielding power and glossiness are inferior.

The metal deposition layer has a function of imparting reflectance, shielding power, and glossiness, but a single layer alone may cause oxidation in high temperature and high humidity conditions in a flexible circuit board manufacturing process, and may cause problems in heat resistance, chemical resistance, and adhesion. Can be generated. Therefore, in order to be used as a coverlay film of a flexible printed circuit board, a coating layer capable of protecting the metal deposition layer is required.

According to a preferred embodiment of the present invention, the polymer resin coating layer serving to protect the metal layer preferably has a thickness of 0.01 μm or more and 5 μm or less. If the thickness is less than 0.01 μm, the effect of the protective layer is less. If the thickness is more than 5 μm, problems may occur in terms of flexibility and manufacturing cost, which is not preferable.

Although the resin of the composition which comprises the protective coating layer which concerns on this invention is not limited to this, Acrylic type, polyester type, polyurethane type, epoxy type, vinyl type, such as polymethyl methacrylate or methacrylic acid ester copolymer, At least one of polystyrene, polyamide, urea, and urea may be used, and more preferably, polyurethane alone or acryl may be used alone or in combination of two or more. The resin in the composition may use 20 to 80%, preferably 30 to 60% of the coating layer as a solid weight ratio. If the weight ratio of the resin is too low, the role as a binder cannot be faithfully fulfilled, and if the weight ratio of the resin is too large, the shielding force is bad, which is not preferable.

As the curing agent included in the composition according to the present invention, one or more selected from amine, melamine, phenol, isocyanate and urethane may be used, and preferably the ratio is 0.1 to 20% by weight. Do.

The coating method for forming an adhesive layer on the coverlay film according to the present invention may be applied by comma coating, lip coating, roll coating, gravure coating, etc. At 50 to 200 ° C., it is preferred to cure after coating at a rate of 0.5 to 30 m / min.

In the case of the metal deposition layer according to the present invention, the deposition method of the metal deposition layer is preferably to apply a universal vacuum deposition method, the coating method of the protective coating layer of the deposition layer is a comma coating, lip coating, roll (roll) coating, gravure (gravure) coating and the like can be applied. Curing of the protective coating layer may be selected from a thermal curing method and an ionizing radiation curing method, preferably an ionizing radiation curing method. After application, the curing process may be left at room temperature in a curing process or aged at 50 to 150 ° C. for about 1 to 7 days.

The flexible printed circuit board is welded by attaching a coverlay film provided with a reflective layer, a resin coating layer protecting the metal deposition layer, and an adhesive layer on the circuit surface on which the circuit pattern is formed according to the present invention. In the case of manufacturing, the application of ink, printing, curing, punching, etc. in the FPCB process can be omitted, so the economic effect is also great.

Hereinafter, the Example and comparative example of this invention are demonstrated in detail.

Example 1

Aluminum oxide is deposited by vacuum deposition on a polyimide 12.5 μm film that is an insulating film. The optical density of the deposited layer was 0.9. Then, 95 parts by weight of a urethane acrylate oligomer (EB9970, manufactured by SKUCB) and 5 parts by weight of a photopolymerization initiator (IRGACURE184, manufactured by Ciba) were mixed, and methyl ethyl ketone (MEK , methyl ethyl keton) was applied on the aluminum deposition layer, and the protective resin coating layer was cured through UV rays. The total thickness of the aluminum oxide deposited layer and the protective coating layer was applied to 3 μm to form a metal deposition layer and a protective resin coating layer which are reflective layers.

Epoxy-based adhesive (adhesive applied to 9C1L-0000 (4S), manufactured by Toray Saehan Co., Ltd.) was coated on the back side of the base film on which the metal deposition layer as the reflective layer was formed, and then dried at 160 ° C. for 5 minutes to release the film as an adhesive layer protective substrate. (XD5BR, manufactured by Toray Saehan Co., Ltd.) and a coverlay film having an adhesive thickness of 25 μm after lamination was prepared.

Example 2

Aluminum oxide is deposited by vacuum deposition on a polyimide 12.5 μm film that is an insulating film. The optical density of the deposited layer was 0.7, and then mixed with 90 parts by weight of acrylic resin (DAI-3A, manufactured by shensho) and 10 parts by weight of isocyanate-based curing agent (DAI-3B, manufactured by shensho) as a curing agent. It was dissolved in toluene and then coated on the aluminum deposition layer, and dried at 140 ° C. for 10 minutes, so that the total thickness of the aluminum oxide deposition layer and the protective coating layer of the deposition layer was 3 μm to form a deposition layer and a protective coating layer. It was.

Epoxy-based adhesive (adhesive applied to 9C1L-0000 (4S), manufactured by Toray Saehan Co., Ltd.) was coated on the back side of the base film on which the metal deposition layer as the reflective layer was formed, and then dried at 160 ° C. for 5 minutes to release the film as an adhesive layer protective substrate. (XD5BR, manufactured by Toray Saehan Co., Ltd.) and a coverlay film having an adhesive thickness of 25 μm after lamination was prepared.

Comparative Example 1

A reflective coverlay film was prepared in the same manner as in Example 1, except that the protective coating layer of the deposition layer was not applied under the conditions of Example 1.

Comparative Example 2

The optical density of the aluminum oxide deposited layer was prepared to be 0.2 under the conditions of Example 1, and a reflective coverlay film was prepared in the same manner as in Example 1.

Comparative Example 3

In the condition of Example 1, after the photosolder resist (PSR, manufactured by SPI-707 SCRL TECH Co., Ltd.) was printed on the surface of the coverlay by a silk screen method instead of the metal deposition layer serving as the reflective layer, UV curing and thermal curing (150 ° C. 1). Time) was carried out to prepare a coverlay film having a thickness of the photosolder layer of 15 µm.

Experimental Example

The reflective coverlay films prepared by the examples according to the present invention and the coverlay films prepared in the comparative examples were evaluated for reflectance, transmittance, heat resistance, and chemical resistance, respectively, as follows. Indicated in;

Reflectance: The average value of the reflectance values measured in the wavelength range between 300 nm-800 nm was measured for each coverlay film by UV-Visible spectrophotometer (UV-3600, the product made by SHIMADZU), and it was set as the reflecting layer average reflectance.

Transmittance: The total light transmittance was measured according to JIS K7105 with a turbidimeter (Haze-meter, NDH-2000) in which the white reflective layer of each coverlay film was apply | coated to the transparent polyester film on the same conditions, respectively.

Heat resistance: After each coverlay film was placed in a high temperature dryer and subjected to heat treatment for 160 ° C for 30 minutes, it was judged whether the reflective layer was discolored.

Chemical resistance: Soak each coverlay film in methyl ethyl ketone (MEK) for 10 minutes at room temperature, take it out, rub it with an industrial wiper (Sontara, manufactured by Dupont) at least 10 times, and if the reflecting layer is damaged, fail or fail. Processed as pass.

Optical density: In order to measure the optical density of each coverlay film vapor deposition layer, it evaluated through the O.D measuring machine (D-200II, Gretag Macbeth company make).

Evaluation item Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Reflective layer thickness (including protective resin layer) 3㎛ 3㎛ 1㎛ 3㎛ 15 μm Optical Density (O.D) 0.9 0.7 0.9 0.2 - Reflectance (UV-visible measurement) 75 60 75 17 10 Total transmittance (shielding force)
(PI + reflective layer + protective layer) 12 17 12 50 14 Heat resistance pass pass fail pass pass Chemical resistance pass pass fail pass pass

As can be seen in Table 1, by applying the metal oxide deposited layer and the resin protective layer according to the present invention, the reflective coverlay film produced is high, compared with the photosolder resist printing coverlay prepared according to the prior art Level of reflectance and low transmittance (high shielding).

In addition, as described above, the reflective coverlay film produced by the embodiment according to the present invention has an extremely high level of reflectance when the conventional coverlay film is replaced with the reflective coverlay film to which the metal deposition layer according to the present invention is applied. It is very economical because it can increase the brightness of the backlight through high shielding, and can reduce the defect rate, shorten the manufacturing time, and reduce the manpower because the complicated PSR ink printing multi-step process can be omitted.

Claims (5)

A metal deposition layer having an average reflectance of 60% or more and a total light transmittance of 30% or less is formed on one surface of the base film, and a coating layer for protecting the deposition layer is coated on the top of the deposition layer, and vice versa. Reflective coverlay film, characterized in that the protective substrate formed on the surface of the adhesive and the release layer sequentially. The method of claim 1, wherein the metal deposition layer is a vacuum deposition method (vaccum deposition method) by depositing a metal containing aluminum or a metal oxide containing SiOx or Al ₂ Ox on the surface of the base film by using a vacuum deposition method (vaccum deposition method) Reflective coverlay film, characterized in that formed to have an optical density). The method of claim 1, wherein the coating layer for protecting the metal deposition layer is formed by coating a polymer resin containing at least one selected from acrylic, polyester, epoxy, urethane-based resin on the metal deposition layer Reflective coverlay film. Forming a metal deposition layer on one surface of an insulating base film such as a polyimide film, a polyester film, an aramid film, and then coating the polymer resin protective layer; And applying a flame-retardant adhesive on the back surface on which the metal deposition layer and the protective layer are formed, and then performing lamination with a release layer substrate on the adhesive coating surface. A metal deposition layer having an average reflectance of 60% or more and a total light transmittance of 30% or less and a resin coating layer protecting the deposition layer are formed on one surface of the base film, and an adhesive and a protective release layer are sequentially formed on the opposite side thereof. And removing the protective release layer of the formed reflective coverlay film, and then bonding the adhesive surface to the circuit surface of the copper clad laminate (CCL) having the circuit pattern formed thereon.