KR20180071045A - Method for direct bonding an printed circuit board with flexible flat cable, power supplying device bonded thereby and display apparatus comprising the same - Google Patents

Abstract

The present invention relates to a method for directly bonding a printed circuit board and a flexible flat cable (FFC) which has excellent mechanical, thermal, and electrical characteristics under a high temperature and high humidity condition and can perform high-temperature solder bonding through a structural design, a connectorless power supply device electrically bonded thereby, and a display device having the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a direct connection method of a flexible printed circuit board and a flexible flat cable, and to a power supply device and a display device connected by the above method. BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] }

An object of the present invention is to provide a direct connection (FFC) having improved connection structure between a flexible flat cable (FFC) having excellent mechanical characteristics, thermal characteristics and electrical characteristics under high temperature and high humidity conditions and a printed circuit board, To a power supply device including a printed circuit board and an FFC electrically connected by the above method, and a display device having the same.

2. Description of the Related Art In general, a display device such as a liquid crystal display (LCD) is widely used as a flat panel display device because it can be driven by a low power and has a clear color reproduction capability. However, unlike a CRT or a PDP, an LCD is a non-light emitting device in which a display panel itself can not emit light directly. A backlight unit (BLU) using a fluorescent lamp or the like is separately required do.

BACKGROUND ART [0002] A backlight used in a liquid crystal display device is divided into a front dimming type (or a direct down type) and a side dim type (or edge type) according to a method of arranging an LED (Light Emitting Diode) light source. In the direct-lighting method, the LED light source is disposed under the diffusion plate of the flat plate. Since the shape of the light source appears on the liquid crystal panel, a space between the light source and the liquid crystal must be sufficiently secured and maintained. Since the light scattering means must be separately installed for distribution, there is a limit to the thinness. In addition, edge-lighting is a method of providing a light source on the side of a light guide panel of a flat plate and then dispersing the light on the entire surface by using a light guide plate, There is room.

On the other hand, in most backlight devices, wiring is generally performed using the general wire cable shown in FIG. 1. In this case, a connector is necessarily used for connection between the circuit board and a general wire cable. The use of such a connector not only increases the cost, but also limits the thickness of the display device due to the increase in the thickness of the component.

In addition, anisotropic conductive film (AFC) or the like may be applied to reduce the thickness of the product. However, in this case, cost increases due to the use of the anisotropic conductive film, process cost increases due to the bonding process, To 280 [deg.] C.

An object of the present invention is to provide a flexible flat cable (FFC) having excellent mechanical properties, thermal characteristics and electrical characteristics even under high temperature and high humidity conditions so that it can be thinned through structural design, To provide a new access method improved.

It is also an object of the present invention to provide a connectorless power supply device which is connected by the above method so as to improve the coupling structure between the flexible flat cable and the printed circuit board and realize low cost while maintaining the connection stability, And a display device provided with the display device.

In order to accomplish the above object, the present invention provides a method of manufacturing a printed circuit board, comprising: (i) applying a solder cream to one side of a printed circuit board; (ii) depositing a flexible flat cable on the coated solder cream, exposing a part of the coated conductor in the insulating film of the flexible flat cable and placing it on the solder cream; (iii) preparing a heat resistant stiffener to which a thermosetting resin adhesive is applied on the first surface; (iv) stacking the first surface of the heat resistant stiffener coated with the thermosetting adhesive so as to cover the exposed conductor and one area of the flexible flat cable in contact with the conductor; And (v) a step of performing a press process on the upper surface of the second surface of the heat resistant stiffener so as to integrally join the printed circuit board with the flexible flat cable.

The present invention also provides a power supply device including a printed circuit board and a flexible flat cable directly connected by the above-described method.

More specifically, the power supply device includes a printed circuit board having a circuit pattern layer formed on one side thereof; A solder layer formed on the circuit pattern layer of the printed circuit board; A flexible flat cable (FFC) disposed on the printed circuit board and bonded on the solder layer in a state that a part of the coated conductor in the insulation film is exposed; A thermosetting adhesive layer formed to surround the exposed conductor and a flexible flat cable in contact with the conductor, the thermosetting adhesive layer being strengthened in adhesion to the heat resistant reinforcement; And a heat-resistant reinforcement disposed on the thermosetting adhesive layer.

In addition, the present invention provides a display device having the power supply device described above.

In the present invention, the printed circuit board included in the power supply unit may be a component that controls a light source of a backlight unit (BLU).

The present invention relates to a flexible flat cable (FFC) and a printed circuit board (PCB) which are excellent in mechanical characteristics and electrical characteristics under high temperature / high humidity environment and have excellent heat resistance characteristics such as heat shrinkability and denaturation, By direct bonding through the connection structure, the final product can be made thinner by improving the connection structure, and the existing soldering process can be applied as it is, thereby ensuring economic efficiency and mass productivity.

In addition, the connectorless type power supply apparatus improved in the coupling structure between the flexible flat cable and the circuit board in the present invention is excellent in mechanical characteristics, heat resistance characteristics and electrical characteristics, It is possible to realize a reduction in cost and a reduction in thickness.

1 is a view showing a conventional general wire cable to which a connector is coupled on one side.
2 is a schematic view illustrating a direct bonding structure between a flexible printed circuit board and a flexible flat cable according to an embodiment of the present invention.
3 is a schematic view illustrating a manufacturing process in which a flexible printed circuit board and a flexible flat cable are directly bonded according to an embodiment of the present invention.
4 is a photograph showing the connection structure of FIG.
Fig. 5 is a graph showing the results of the experiment 2 (Solder joint) and the power supply of Comparative Example 7 (ACF bonding) under severe conditions.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

Recently, display devices such as LED TVs have been continuously required to improve the thickness of the side walls and to reduce the thickness thereof.

Meanwhile, as shown in FIG. 1, a conventional general power cable has a connector at least at one end thereof. When combined with a printed circuit board through such a connector, there is a limitation in reducing the thickness of the final display device, as well as an increase in cost due to the use of the connector.

In addition, an anisotropic conductive film (ACF) or the like may be applied to reduce the thickness of a conventional final display device. However, in this case, the use of a separate ACF film and the addition of a bonding process may result in economical efficiency and lowered mass productivity. Also, since the bonding temperature of the ACF film is about 170-200 캜, there is a limit to the use of the ACF film in the high temperature solder bonding process performed at 260 - 280 캜.

Accordingly, in the present invention, a high heat-resistant flexible flat cable (FFC) applicable to a high-temperature solder bonding process is employed and is bonded to a printed circuit board through soldering so that they are physically and electrically connected directly to each other, Innovative thickness reduction is possible without using a connector (see Figure 2).

Further, in the present invention, a hot-bar process is performed by a press process such as thermocompression using a high-temperature-resistant stiffener at the top of the laminate having the printed circuit board and the flexible flat cable (FFC) . Since the laminate can be integrally bonded by a single process by the heat generated from such hot bar equipment, simplification of the manufacturing process, mass production, and economical efficiency can be ensured.

In addition, the present invention can provide a connectorless type power supply device including a high heat-resistant flexible flat cable and a printed circuit board having improved connection structure through the above-described method, And it is possible to secure the thinning.

<Flexible Flat Cable>

The present invention provides a flexible flat cable (FFC) capable of continuously maintaining high mechanical properties, excellent heat resistance characteristics and electrical characteristics under severe conditions such as high temperature and high humidity.

According to an embodiment of the present invention, the flexible flat cable includes a conductor; And an insulating film in which an adhesive layer, an intermediate layer and a resin layer are laminated in order on at least one surface of the conductor.

More specifically, it has a structure including a plurality of flat plate conductors having a predetermined width and thickness, and at least one insulating film covering one or both surfaces of the conductor. For example, an adhesive layer is laminated on both surfaces of a conductor The intermediate layer is laminated on the other side of the adhesive layer, and the resin layer is laminated on the other side of the intermediate layer.

In the flexible flat cable (FFC) according to the present invention, the type of the conductor is not particularly limited, but may be made of a conductive metal such as copper, tin-plated copper, or nickel-plated copper. As the conductor, a thin conductive metal is preferable.

The thickness and the shape of the conductor are not particularly limited, and conventional conductors known in the art can be used without limitation. For example, in consideration of the sliding property of the flexible flat cable (FFC) 100, the thickness of the conductor may be in the range of 20 to 50 mu m.

In the flexible flat cable (FFC) according to the present invention, the insulating film covering the conductor has a structure in which an adhesive layer, an intermediate layer and a resin layer are laminated in this order.

Here, the adhesive layer serves to bond the insulating film to the conductor, and the intermediate layer is positioned between the adhesive layer and the resin layer to complement the insufficient bonding force when the adhesive layer and the resin layer are directly bonded. The resin layer is located at the outermost edge of the insulation film and allows the conductor to be insulated from the outside.

In the flexible flat cable (FFC) according to the present invention, the ratio of the tensile stress (TR) at room temperature to the tensile stress (TH) after maintaining the insulating film at a temperature of 85 占 폚 and a humidity of 85% TR) is from 0.9 to 1.0, more preferably from 0.93 to 1.0.

In the present invention, the ratio (TH / TR) of the tensile stress (TR) at room temperature to the tensile stress (TH) after maintaining the insulating film at a temperature of 85 DEG C and a humidity of 85% The same and similar mechanical properties as the room temperature condition can be maintained. On the other hand, when the TH / TR ratio is less than 0.9, the crosslinked chain in the polymer resin contained in the adhesive layer or the intermediate layer is broken, and mechanical strength and bending property may be significantly deteriorated. Therefore, in the present invention, it is desirable to control the ratio (TH / TR) of the tensile stress (TR) at room temperature to the tensile stress (TH) after maintaining the insulating film at 85 ° C and 85% However, it is desirable to control to 1.0 or less in consideration of feasibility and economic situation.

According to another embodiment of the present invention, the insulating film has a high elongation (EH) of 85 to 105% after being maintained for 1000 hours under a condition of a temperature of 85 and a humidity of 85%, that is, under harsh conditions.

In the present invention, the tensile stress (TR) at room temperature of the insulating film may have a high value of 130 to 140 MPa.

In addition, in the present invention, the insulating film may have a very high tensile stress (TH) of 115 to 135 MPa after the insulation film is maintained under a severe condition of 85 ° C and 85% humidity for 1000 hours.

In the present invention, the insulation film provided as described above has a shrinkage ratio in the longitudinal direction (MD) of 0.20 to 0.35%, a shrinkage ratio in the width direction (TD) of 0.08 to 0.13%, and a shrinkage ratio in the width direction (MD / TD) of the shrinkage ratio of 2.5 to 3.0 can be further improved.

In the insulating film of the present invention, the adhesive layer may include a polymer resin, and the polymer resin may be a polyester resin, a polyimide resin, a polyethylene resin, a polyurethane resin, and a polyphenylene sulfide resin At least one selected from the group consisting of a polyester resin and a polyester resin.

As the polyester resin usable as the polymer resin in the present invention, it is preferable to use two or more kinds of polyester resins, more preferably a first polyester resin having a molecular weight of 1,000 to 15,000, (PE) resin having a weight-average molecular weight (Mw) of 35,000 or a mixture thereof, more preferably two or more of the first polyester resins, two or more of the second polyester resins or one or more of the first polyester resins And one or more second polyester resins may be used, but most preferably a mixture of at least one first polyester resin and at least one second polyester resin may be used.

However, the types of polyester resins usable in the present invention are not limited to those described above, but may be selectively used depending on the characteristics of the product to be implemented.

In the insulating film of the present invention, it is preferable that the adhesive layer includes at least one curing agent.

At this time, the kind of the curing agent may be a compound containing at least one functional group of an isocyanate group, a block isocyanate group, and a carbodiimide group. More specifically, the present invention relates to a process for producing a polyisocyanate compound, which comprises reacting 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, xylene diisocyanate, isophorone diisocyanate, polyethylene phenyldiisocyanate and hexamethylene A polyisocyanate, a polyisocyanate, a polyisocyanate, a polyisocyanate, a polyisocyanate, a polyisocyanate, a polyisocyanate, a polyisocyanate, a polyisocyanate, a polyisocyanate, and a polyisocyanate, no.

In the present invention, the curing agent is used in an amount of 6 to 60 parts by weight, preferably 6 to 26 parts by weight, more preferably 8 to 22 parts by weight, more preferably 8 to 8 parts by weight, based on 50 parts by weight of the polymer resin contained in the adhesive layer. To 18 parts by weight can further improve mechanical properties such as tensile strength, elongation and heat shrinkage and flexural properties. When the content of the polymer resin is 100 parts by weight, the content of the curing agent may be doubled.

In the present invention, at least 6 parts by weight of a curing agent relative to 50 parts by weight of the polymer resin is used to obtain the above-mentioned effect, and more preferably 8 parts by weight or more of the curing agent is required to cause cross-linking between the polyesters It is possible to exhibit excellent mechanical properties even under severe conditions. However, when the curing agent is used in an amount of more than 26 parts by weight, the adhesive layer becomes hard, resulting in poor flexibility and flexibility, and a low elongation percentage.

Further, in the present invention, one or more flame retardant fillers may be further added to impart the flame retardancy to the adhesive layer.

Although the type of the flame retardant filler is not particularly limited, the flexible flat cable (FFC) according to the present invention has a flame retardancy that passes the UL standard vertical burning test (VW-1 test) owing to the addition of the flame retardant filler .

More specifically, as the flame retardant filler, at least one selected from the group consisting of a halogen flame retardant, a phosphorus flame retardant, a nitrogen flame retardant, a metal flame retardant and an antimony flame retardant may be used, and preferably at least one kind And more preferably 3 kinds or more and 5 kinds or less of compounds may be mixed and used.

Specific examples of the flame retardant in the present invention include chlorine-based flame retardants such as chlorinated paraffin, chlorinated polyethylene, chlorinated polyphenyl and perchloropentacyclodecane; Ethylene bispentabromobenzene, ethylene bispentabromodiphenyl, tetrabromoethane, tetrabromobisphenol A, hexabromobenzene, decabromobiphenyl ether, tetrabromophthalic anhydride, polydibromophenylene oxide, Brominated flame retardants such as hexabromocyclodecane and ammonium bromide; Alkyl phosphates, alkyl phosphates, dimethyl phosphonates, phosphonates, halogenated phosphonate esters, trimethyl phosphates, tributyl phosphates, trioctyl phosphates, tributoxyethyl phosphates, octyldiphenyl phosphates, tricresyl phosphates, Tris (2-chloropropyl) phosphate, tris (2,3-dichloropropyl) phosphate, tris (2,3-dibromopropyl) phosphate, dicyclohexylphosphine, (Chloropropyl) monooctyl phosphate, polyphosphonate, polyphosphate, aromatic polyphosphate, di (2-ethylhexyl) phosphate, tris (bromocloropropyl) phosphate, bis Phosphoric acid esters such as bromo neopentyl glycol and tris (diethylphosphinic acid) aluminum Is a compound; Polyols such as phosphonate type polyols, phosphate type polyols and halogen element-containing polyols; Aluminum hydroxide, magnesium hydroxide, magnesium carbonate, antimony trioxide, antimony trichloride, zinc borate, antimony borate, boric acid, antimony molybdate, molybdenum oxide, phosphorus oxide, calcium silicate, titanium dioxide, zirconium compound, tin compound , A metal powder or an inorganic compound such as oxonite, calcium aluminate hydrate, copper oxide, metallic copper powder, calcium carbonate and barium metaborate; Nitrogen compounds such as melamine cyanurate, triazine, isocyanurate, urea, guanidine and the like; And other compounds such as silicone-based polymers, ferrocene, fumaric acid, and maleic acid. Among them, halogen-based flame retardants such as a bromine-based flame retardant and a chlorine-based flame retardant are preferable.

In the present invention, the content of the flame retardant filler is not particularly limited, but it is preferably at least 5 parts by weight, preferably at least 10 parts by weight, more preferably at least 15 parts by weight based on 50 parts by weight of the polymer resin The upper limit of the amount is preferably 75 parts by weight, preferably 65 parts by weight, more preferably 60 parts by weight. If the content of the flame retardant filler exceeds the upper limit value described above, the effect of improving the flame retardancy may not be sufficiently improved as compared with the increase in the addition amount, which may be economically problematic and the flexibility may be lowered and the elongation percentage may be lowered due to the increase of the filler content.

In the present invention, additives such as a flame retardant additive, a pigment, an antioxidant, a masking agent, a lubricant, a processing stabilizer, a plasticizer, a foaming agent reinforcing agent, A colorant, a filler, a granule, a metal deactivator, a silane coupling agent, and the like.

The present invention provides a method for producing the above-described insulating film.

More specifically, a preferred embodiment for producing the insulating film includes the steps of mixing and synthesizing at least one polyester resin, at least one curing agent, and at least one flame-retardant filler to prepare a first solvent; Mixing and synthesizing at least one polyester resin, at least one curing agent, and an inorganic filler to prepare a second solvent; Coating the resin layer with the second solvent to form an intermediate layer; And coating and drying the first solvent on the intermediate layer to form an adhesive layer.

In the method for producing an insulating film, the polyester resin, the curing agent and the flame-retardant filler are overlapped with those described in the above-mentioned insulating film, and detailed description thereof is omitted.

The kind of the inorganic filler used for the production of the second solvent is not particularly limited, and for example, silica (SiO ₂ ) can be used.

The present invention also provides a method of manufacturing a flexible flat cable (FFC) including the above-described insulating film.

More specifically, a preferred embodiment for manufacturing the flexible flat cable (FFC) includes: preparing two insulating films; And interposing a conductor between the adhesive layers of the two insulating films and then joining them.

In the present invention, it is possible to further perform a step of cutting the insulating film to a desired size before attaching the insulating film to the conductor.

The thickness of the flexible flat cable including the above-described configuration is not particularly limited, and may be in the range of 100 to 300 mu m, and preferably in the range of 100 to 150 mu m, for example.

&Lt; Direct bonding method of flexible printed circuit board and flexible flat cable &

The present invention also provides a method of direct bonding to a printed circuit board (PCB) through soldering using a flexible flat cable (FFC) having the above-described high heat resistance, mechanical properties and excellent electrical properties.

Hereinafter, a direct connection method between the printed circuit board and the flexible flat cable according to the present invention will be described. However, the present invention is not limited to the following method, and the steps of each process may be modified or selectively mixed if necessary.

According to a preferred embodiment of the connecting method, (i) a step of applying a solder cream to one side of a printed circuit board (step S10); (ii) depositing a flexible flat cable on the coated solder cream, placing the coated conductor in the insulation film of the flexible flat cable on the solder cream in an exposed state (step 'S20'); (iii) preparing a heat-resistant stiffener coated with a thermosetting resin adhesive on the first side (step S30); (iv) a step (S40) of stacking the first surface of the heat resistant stiffener coated with the thermosetting adhesive so that one side of the flexible flat cable contacting the exposed conductor and the conductor is covered; And (v) a hot-bar process is performed on the second surface of the heat-resistant stiffener by a press process such as thermal compression (heat fusion) so as to integrally join the process (Step S50) And the like.

2 and 3 are views schematically showing a direct bonding structure between a printed circuit board and a flexible flat cable (FFC) according to an embodiment of the present invention and a connecting process therefor.

Hereinafter, the process steps will be described with reference to FIGS. 2 to 3. FIG.

(1) Solder cream application step (hereinafter referred to as step S10)

In the step S10, the solder cream 20 is applied on one side of the printed circuit board 10.

In the present invention, the printed circuit board (PCB) 10 can use any conventional circuit board known in the art without limitation. For example, the printed circuit board 10 may include a plurality of chips related to a light source, a backlight driving circuit, a camera driving circuit, a power driving circuit, and the like.

The printed circuit board 10 may be a printed circuit board 10 that is electrically connected to a light source that generates light and that supplies power to the light source. A circuit pattern (terminal) of a predetermined shape is formed on at least one surface of the printed circuit board 10, and in particular, a copper circuit pattern layer (not shown) and a photo solder resist (PSR) layer for insulating the circuit layer are formed (MPCB) which is formed on the printed circuit board.

Here, the shape, thickness, and position of the circuit pattern layer are not particularly limited and can be freely modified according to the needs of the user. For example, the circuit pattern layer may be formed on one side or both sides of the printed circuit board 10, and may be formed in a predetermined shape along the length or thickness direction of the printed circuit board 10.

The solder cream 20 applied on one side of the printed circuit board 10 may be any conventional one known in the art and its component and application amount is not particularly limited as long as it can be electrically connected to other electrical and electronic components . For example, Sn-Pb-based, Sn-Ag-based, and Sn-Bi-based solders can be used.

In the step S10, the solder cream 20 is preferably applied so as to cover the circuit pattern layer of the printed circuit board 10.

(2) Flexible Flat Cable Laminating Step (hereinafter referred to as Step S20)

In this step, in order to electrically connect the printed circuit board 10 and the flexible flat cable 30, a flexible flat cable 30 is stacked on the solder cream 20, A part of the coated conductor 31 in the insulating film (not shown) is exposed and placed on the solder cream 20. [

Here, the flexible flat cable 30 is the same as the above-described structure. For example, (i) a single-sided insulation film in which a plurality of conductors, an adhesive layer and a resin layer are sequentially laminated, or (ii) A two-sided type insulating film in which an adhesive layer and a resin layer are sequentially laminated on the upper and lower surfaces of the conductor, respectively.

The flexible flat cable 30 has a single-sided insulation film on which a conductor is directly exposed on one side in order to connect the flexible flat cable 30 to a connection terminal formed on the printed circuit board 10 or other electric / Or one side of the insulating film is removed from the double-sided insulating film so that a part of the conductor 31 is exposed to the outside.

In step S20, the flexible flat cable 30 can be freely disposed in consideration of the circuit pattern layer of the printed circuit board 10. [ For example, when the circuit pattern layer is formed at one end in the longitudinal direction of the printed circuit board, the flexible flat cable 30 can be arranged in a direction in which the longitudinal direction of the printed circuit board 10 intersects. However, it is not particularly limited.

(3) Heat-resistant stiffener preparation step (hereinafter referred to as step S30)

In this step, a heat resistant stiffener 50 to be disposed on the upper portion of the flexible flat cable 30 is prepared.

In the present invention, the heat-resistant stiffener 50 can be used without limitation as a conventional stiffener known in the art.

Specifically, the heat resistant stiffener 50 may be made of a high heat resistant resin or an engineering plastic that can withstand a high temperature / high pressure condition of a pressing process, preferably a hot-bar process, which will be described later, without changing physical properties. Preferably, the polyimide-based film or sheet is a polyimide-based polyimide film having an extrusion processing temperature of at least 350 ° C, preferably 350 to 380 ° C.

On the other hand, since the heat resistant stiffener 50 should exhibit excellent adhesive strength with the flexible flat cable 30 disposed under the heat resistant stiffener 50, it is preferable that the thermosetting resin adhesive 40 is applied on the first surface.

Accordingly, the thermosetting resin adhesive 40 may be applied on the first surface of the heat resistant stiffener 50 and used. In this case, the coating method and the coating amount are not particularly limited and can be appropriately adjusted within the conventional range known in the art. In addition, a commercially available reinforcing material 50 may be used as it is while the adhesive 40 is applied to the first surface. In this case, the release film on the surface to which the adhesive is applied may be used before use.

The thermosetting resin adhesive 40 applied on the first surface of the heat resistant stiffener serves to strengthen the physical connection with another substrate physically contacting the heat resistant stiffener 50, for example, the flexible flat cable 30 do. Further, the thermosetting resin adhesive 40 should have a good adhesive property as a result of rapid internal fast curing by heat generated by a hot-bar process.

The thermosetting resin adhesive 40 may be composed mainly of a conventional epoxy resin and a curing agent known in the art, and may further include other thermosetting resins, conventional thermoplastic resins, curing accelerators, and the like.

According to a preferred embodiment of the present invention, the thermosetting resin adhesive 40 includes an epoxy resin and a curing agent and is a fast curing epoxy adhesive having a curing degree of 90% or more at 260 ° C or higher, for example, at 260 to 380 ° C within 30 minutes , And a glass transition temperature (Tg) of 70 to 100 ° C.

The epoxy resin may be any conventional epoxy resin known to those skilled in the art. It is preferable that two or more epoxy groups are present in the molecule without containing a halogen element. Examples of usable epoxy resins include, but are not limited to, bisphenol A type / F type / S type resin, novolak type epoxy resin, alkylphenol novolak type epoxy resin, biphenyl type, aralkyl type, naphthol Naphthol type, dicyclopentadiene type, or mixed form thereof.

More specific examples thereof include epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, naphthalene type epoxy resin, anthracene epoxy resin, biphenyl type epoxy resin, Cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol S novolak type epoxy resin, biphenyl novolac type epoxy resin, naphthol novolak type epoxy resin, naphthol phenol coaxial novolak type epoxy resin , Naphthol cholizole co-novolak type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy resin, triphenyl methane type epoxy resin, tetraphenyl ethane type epoxy resin, dicyclopentadiene phenol addition reaction type epoxy resin, phenol aral A quarternary epoxy resin, a polyfunctional phenol resin, a naphthol aralkyl type epoxy resin There is. At this time, the above-mentioned epoxy resin may be used alone, or two or more epoxy resins may be used in combination. The bisphenol A type epoxy resin and the cresol novolak type epoxy resin are preferably used in combination.

In the present invention, conventional curing agents known in the art can be used without limitation, and can be appropriately selected depending on the type of epoxy resin to be used. Non-limiting examples of usable curing agents include phenolic, anhydride, dicyanamide, and aromatic polyamine curing agents. Non-limiting examples of usable curing agents include phenolic curing agents such as phenol novolak, cresol novolac, bisphenol A novolac, naphthalene type and the like; And polyamine type curing agents such as metaphenylenediamine, diaminodiphenylmethane (DDM) and diaminodiphenylsulfone (DDS). These may be used singly or in combination of two or more kinds. It is preferably a diaminodiphenylsulfone (DDS) curing agent. In this case, the content of the curing agent is not particularly limited, and may be in the range of 5 to 10 parts by weight based on 100 parts by weight of the entire thermosetting resin adhesive.

As a preferred example of the present invention, the thermosetting resin adhesive (40) comprises 20 to 70 parts by weight of a bisphenol A epoxy resin, 1 to 30 parts by weight of a cresol novolak epoxy resin, and 1 to 15 parts by weight of a diaminodisphenyl sulfone curing agent And the like.

The thermosetting resin adhesive 40 of the present invention constituted as described above may have a peel strength of 1.5 to 1.7 kgf / cm at a thickness of 20 to 25 mu m. The resin flow may be 70 to 80 탆, and the glass transition temperature may be 70 to 100 캜, preferably 70 to 80 캜. In addition, it may be passing the solder float (@ 300 ° C, 10 sec) test.

(4) Heat-resistant stiffener Stacking step (hereinafter referred to as 'S40 step')

The heat resistant stiffener 50 is laminated on the exposed conductor 31 of the flexible flat cable 30 so that the first surface coated with the thermosetting adhesive 40 is exposed to the exposed conductors 31 and And the flexible flat cable 30 in contact with the conductor is laid so as to cover one area.

The structure of the stacked body as described above is shown in FIG.

(5) Bonding step using press process (hereinafter referred to as 'S50 step')

In step S50, the uppermost surface of the laminated body stacked in the previous step S40, that is, the upper surface of the second surface of the heat resistant stiffener 50 is subjected to a pressing process to integrally join the laminated body.

Here, the press process may be performed using any conventional press equipment known in the art, for example, a hot-bar process can be performed. This hot-bar process is a heat-press joining by applying heat and pressure through hot-bar equipment as a heating and pressing member. In this case, since the equipment is simple, the process speed is high, and mass production is possible, it is environmentally friendly and economical by other conventional methods.

The press process conditions in the step S50 can be appropriately controlled within a conventional range known in the art. For example, the press process may be performed at a temperature of 260 to 380 DEG C and a pressure of 0.1 to 10 MPa for 10 seconds to 5 minutes using a hot bar apparatus Followed by thermocompression, preferably at a temperature of 260 to 360 ° C and a pressure of 0.1 to 5 MPa for 10 seconds to 5 minutes.

When the thermocompression bonding is performed through the hot bar equipment, the generated heat is conducted from the heat-resistant stiffener 50, which is the uppermost portion of the laminate, to the lowermost portion of the printed circuit board 10. Curing of the thermosetting resin adhesive 40 in accordance with the conduction of such heat; And the soldering process of the solder cream 20 are performed at the same time, so that the short-time laminate is integrally joined by a single process. For example, when the hot bar process is performed at 350 to 380 캜, the generated heat is directly transferred to the heat resistant stiffener 50 having the uppermost part, the flexible flat cable 30 at the lower part is transferred to the solder cream 20 at 280 to 300 캜, 260 to 280 ° C or so.

The structure of the printed circuit board 10 and the flexible flat cable 30 connected through the above-described method is shown in Fig.

<Power supply>

In addition, the present invention provides a power supply for a light source, preferably a light source for a display device, comprising a printed circuit board and a flexible flat cable that are directly bonded by the above-described method.

More specifically, the power supply device includes a printed circuit board 10 on one side of which a circuit pattern layer is formed; A solder layer 20 formed on the circuit pattern layer of the printed circuit board 10; A flexible flat cable (FFC) 30 disposed on the printed circuit board 10 and bonded onto the solder layer 20 in a state that a part of the conductor 31 coated in the insulating film is exposed; A thermosetting adhesive layer 40 which is formed so as to cover a part of the exposed conductor 31 and the flexible flat cable 30 in contact with the conductor and which enhances adhesion with the heat resistant stiffener 50; And a heat resistant stiffener (50) disposed on the thermosetting adhesive layer (40).

In the present invention, the power supply device is a connectorless type connecting structure in which a printed circuit board, a flexible flat cable and a heat-resistant stiffener are integrally joined to each other. Thus, by physically and electrically connecting the high heat-resistant flexible flat cable (FFC) to the printed circuit board by conventional solder bonding without using a separate connector, innovative thickness and volume reduction are possible.

The power supply device of the present invention may include a plurality of printed circuit boards differing from each other in terms of structure and / or function. At this time, the printed circuit boards may be connected in series through both ends of the flexible flat cable.

In addition, the power supply device may include a plurality of flexible flat cables, wherein both ends of the printed circuit board may be directly connected to the respective flexible flat cables.

More specifically, the power supply device of the present invention includes: a first printed circuit board including terminals and having a plurality of light sources (e.g., LED chips) mounted thereon; A second printed circuit board including a terminal and providing power to the first printed circuit board; And a flexible flat cable, wherein both ends of the flexible flat cable are connected in series between terminals of the first printed circuit board and the second printed circuit board, wherein both ends of the printed circuit board are connected to respective flexible They can be directly connected to the flat cable and electrically connected.

INDUSTRIAL APPLICABILITY The power supply device of the present invention not only has an improved connection structure with other electrical and electronic parts through structural design modification but also essentially uses a high heat resistant FFC, a high heat resistant adhesive and a high heat resistant stiffener, Thermal characteristics and electrical characteristics similar to or similar to normal temperature conditions under a test for evaluating the reliability of the electronic component package, for example, a high temperature and high humidity test.

According to an embodiment of the present invention, the flexible flat cable provided in the power supply device has tensile stress (TR) at room temperature with respect to tensile stress (TH) after holding for 1000 hours under the conditions of 85 캜 and 85% (TH / TR) may be 0.9 to 1.0. And preferably 0.93 to 1.0.

According to another embodiment of the present invention, the flexible flat cable provided in the power supply device may have a contact resistance (? _HTHH ) value of 10 m? _Or less after holding for 500 hours under conditions of a temperature of 85 占 폚 and a humidity of 85%. Preferably 6.0 m? Or less.

According to another embodiment of the present invention, the peel strength value of the flexible flat cable to the printed circuit board after the power supply device is maintained at a temperature of 85 ° C and a humidity of 85% for 500 hours is in the range of 1.00 to 5.00 kgf / cm &lt; / RTI &gt; Preferably 1.20 to 5.00 kgf / cm.

<Display device>

Further, the present invention provides a display device including the power supply device described above.

Here, the display device can be applied to a conventional flat panel display device known in the art without limitation, and examples thereof include a liquid crystal display (LCD), a light emitting diode (LED), a touch panel, A field emission display (FED), a PDA, a plasma display panel (PDP), a backlight unit (BLU), a light source component, and the like.

A display device according to an embodiment of the present invention includes a light source and a power supply unit electrically connected to the light source and supplying power to the light source.

More specifically, the present invention relates to a flat panel display panel for displaying an image; A light source for outputting light to the flat panel; And a power supply for supplying power to the light source. Here, the metal printed circuit board included in the power supply unit may be a part for controlling a light source, preferably a light source of a backlight unit (BLU).

At this time, the light source and the power supply may be separately provided, or the light source may be already mounted on the metal printed circuit board of the power supply. In the case of a light source mounted on a metal printed circuit board, it may have a structure electrically connected to a flexible flat cable.

The power supply device has flexibility and flatness, does not include a connector and occupies a considerably small volume, thereby contributing to the thinning of the display device. The display device of the present invention having such a power supply device can be applied to both of the conventional front illuminated type (direct down type) and the side illuminated type (edge type), and in particular, the side illuminated type (or edge type) desirable.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

 [Examples 1 to 6 and Comparative Examples 1 to 6]

<1-1. Insulation Film Manufacturing>

25 parts by weight of a reactive polyester resin (molecular weight 8,000 / glass transition temperature 61 DEG C) and reactive polyester resin (molecular weight 30,000 / glass transition temperature 80 DEG C, respectively) were dissolved in a solvent composed of toluene 80 and 90 parts by weight of methyl ethyl ketone A resin solution was prepared and 50 parts by weight of a flame retardant filler for improving flame retardancy was added and mixed. The isocyanate curing agent was added in the amounts shown in Table 1 to prepare a first solvent for the adhesive layer of 2,000 cps or more. The isocyanate curing agent was added immediately prior to coating with a factor affecting the elapsed time of the resin composition to prepare a mixture.

Further, 20 parts by weight of silica was added to 80 parts by weight of a mixed resin of a polyester resin (molecular weight 5,000 / glass transition temperature 51 DEG C) and a reactive polyester resin (molecular weight 20,000 / glass transition temperature 35 DEG C) . A second solvent was coated on one surface of a stretched polyethylene film in a coating amount of 10 g / m ² in a comma-coat method and dried to form an intermediate layer. Then, a first solvent was coated on the intermediate layer in an amount of 100 g / m ² And dried to form an adhesive layer having a thickness of 20 mu m to produce an insulating film.

<1-2. Flexible Flat Cable Manufacturing>

As described above, a conductor having a thickness of 35 탆 was interposed between two adhesive layers of the insulation film prepared in 1-1, and then laminated at a speed of 0.8 m / min to obtain Flexible Plates of Production Examples 1 to 6 and Comparative Examples 1 to 6 Cable (FFC).

<1-3. Power Supply Manufacturing>

The solder cream was applied on the circuit pattern of the metal printed circuit board, and flexible flexible cables of Production Example 1-6 and Comparative Example 1-6 in which conductors were exposed were laminated on the solder cream. Thereafter, a polyimide reinforcing material having a composition of 70 parts by weight of bisphenol A epoxy resin, 25 parts by weight of cresol novolak epoxy resin, and 5 parts by weight of a diaminodiphenyl sulfone curing agent, to which an epoxy thermosetting adhesive (glass transition temperature: 72 ° C) The laminate was placed in the hot bar equipment and pressed for 15 seconds under the conditions of a temperature of 350 DEG C and a pressure of 0.2 MPa to obtain a power source of each of Examples 1 to 6 and Comparative Examples 1 to 6 Respectively.

[Comparative Example 7]

An anisotropic conductive film (CP7652K, manufactured by Dextelles Co., Ltd.) and a flexible flat cable having a conductor exposed at one end thereof were sequentially laminated on the circuit pattern of the metal printed circuit board, and then pressed for 20 seconds under the conditions of 180 ° C and 0.2 MPa The power supply device of Comparative Example 7 was manufactured.

An anisotropic conductive film (CP7652K, manufactured by Dextelles Co., Ltd.) and a flexible flat cable having a conductor exposed at one end thereof were sequentially laminated on the circuit pattern of the metal printed circuit board, and then pressed for 20 seconds under the conditions of 180 ° C and 0.2 MPa The power supply device of Comparative Example 7 was manufactured.

division Composition (parts by weight) The first polyester
(Molecular weight: 1,000 to 15,000) The second polyester
(Molecular weight 20,000 to 35,000) Hardener Flame retardant filler Production Example 1 25 25 8 50 Production Example 2 25 25 10 50 Production Example 3 25 25 14 50 Production Example 4 25 25 18 50 Production Example 5 25 25 22 50 Production Example 6 25 25 26 50 Comparative Example 1 25 25 One 50 Comparative Example 2 25 25 3 50 Comparative Example 3 25 25 5 50 Comparative Example 4 25 25 - 50 Comparative Example 5 50 - 14 50 Comparative Example 6 - 50 14 50

[Experimental Example 1]

The insulation films prepared in Production Examples 1 to 6 and Comparative Examples 1 to 6 were maintained at room temperature (TR) and temperature (TH) of 85 ° C and 85% humidity for 1000 hours, , And the results are shown in Table 2. &lt; tb &gt; &lt; TABLE &gt; The curing agent content is based on 50 parts by weight of polyester.

Hardener content Room temperature tensile stress
(TR) High temperature and high humidity tensile stress
(TH) Curing agent content and tensile stress ratio
(TH / TR) Production Example 1 8 134 128 0.96 Production Example 2 10 138 131 0.95 Production Example 3 14 139 129 0.93 Production Example 4 18 135 125 0.93 Production Example 5 22 131 118 0.90 Production Example 6 26 130 117 0.90 Comparative Example 1 One 115 88 0.77 Comparative Example 2 3 119 94 0.79 Comparative Example 3 5 128 108 0.84 Comparative Example 4 - 112 75 0.67 Comparative Example 5 14 89 72 0.81

As shown in Table 2, the insulating films of Production Examples 1 to 6 according to the present invention exhibited excellent properties in a severe condition as compared with a room temperature condition in the range of TH / TR of 0.90 to 0.96. However, in Comparative Examples 1 to 6, the mechanical characteristics under severe conditions were much lower than those at room temperature.

[Experimental Example 2]

The elongation ratios (EH) of the insulating films prepared in Production Examples 1 to 6 and Comparative Examples 1 to 6 after maintaining the elongation (ER) at normal temperature and the temperature at 85 ° C and the humidity at 85% for 1000 hours were evaluated, Table 3 shows the results. The curing agent content is based on 50 parts by weight of polyester.

Hardener content Room temperature elongation
(ER) High temperature and high humidity extensibility
(EH) Production Example 1 8 120 92 Production Example 2 10 123 97 Production Example 3 14 125 103 Production Example 4 18 121 105 Production Example 5 22 104 89 Production Example 6 26 109 85 Comparative Example 1 One 104 77 Comparative Example 2 3 109 78 Comparative Example 3 5 117 82 Comparative Example 4 - 98 75 Comparative Example 5 14 85 75

As shown in Table 3, the insulating films of Production Examples 1 to 6 according to the present invention had a high elongation (EH) of 85 to 105% after holding at 85 ° C and 85% humidity for 1000 hours have. On the other hand, it can be seen that the insulation films of Comparative Examples 1 to 6 had a stretch ratio (EH) of 75 to 82% at a severe condition after being maintained at a temperature of 85 DEG C and a humidity of 85% for 1000 hours.

[Experimental Example 3]

The insulating films prepared in Production Examples 1 to 6 and Comparative Examples 1 to 6 were maintained for 1000 hours under conditions of a heat shrinkage rate of 85 DEG C and a humidity of 95% for 1000 hours and a temperature of 85 DEG C and a humidity of 85% The results are shown in Table 4 below.

However, specific evaluation criteria for the above flexibility and appearance are as follows.

1. Flexibility assessment

Under the conditions of temperature 85 ° C and humidity 95%, the number of times of insulation film was measured by sliding the insulation film until the resistance of the conductor increased by at least 10% compared to the conventional one.

?: 100,000 times or more,?: 70 to 100,000 times,?: 50 to 70,000 times, X: 50,000 times or less

2. Appearance evaluation

The evaluation was made as to whether delamination occurred under the conditions of a temperature of 85 캜 and a humidity of 85%.

?: Occurrence of delamination over 2,000 hours,?: Occurrence of delamination between 1,500 and 2,000 hours,?: Occurrence of delamination between 1,000 and 1,500 hours, X: delamination of delamination below 1,000 hours

Hardener content MD TD MD / TD flexibility Appearance Example 1 8 0.30 0.10 3 ◎ ◎ Example 2 10 0.20 0.08 2.5 ◎ ◎ Example 3 14 0.20 0.08 2.5 ◎ ◎ Example 4 18 0.20 0.08 2.5 ○ ○ Example 5 22 0.20 0.08 2.5 ○ ○ Example 6 26 0.20 0.08 2.5 ○ ○ Comparative Example 1 One 0.75 0.25 3 △ △ Comparative Example 2 3 0.60 0.20 3 ○ ○ Comparative Example 3 5 0.40 0.15 2.67 ○ ○ Comparative Example 4 - 0.80 0.30 2.67 △ △ Comparative Example 5 14 0.35 0.13 2.69 △ △

As shown in Table 4, the insulating films of Production Examples 1 to 6 according to the present invention had MDs of about 0.2 to 0.3% and TDs of 0.08 to 0.10% It can be seen that the heat shrinkage ratio has a remarkably low value, and the properties of flexibility and appearance are also excellent.

[Experimental Example 4: Evaluation of physical properties of power supply device]

A high temperature and high humidity test (HTHH) was performed using the power supply device prepared in Example 2 and Comparative Example 7 as described below.

The contact resistance and the peel strength (P / S) of the flexible flat cable manufactured in Example 2 and Comparative Example 7 were measured after being maintained at a temperature of 85 ° C and a humidity of 85% for 500 hours The results are shown in Table 5 and FIG.

The evaluation method and evaluation criteria of Experimental Example 4 are as follows.

1) The contact resistance of the flexible flat cable was measured using a Keysight B2901A Source Meter.

2) Adhesion strength was measured at 90 ° (vertical) and 180 ° (horizontal) adhesive force (kgf / cm) on a printed circuit board at a speed of 300 mm / min at a flexible flat cable and Instron 8942 UTM was used .

division Example 2 Comparative Example 7 FPCB FFC Bonding method Solder joint Anisotropic conductive bonding (ACF bonding) Adhesive strength
(kgf / cm) 90 degrees 1.35 1.38 180 degrees 1.28 1.25 Contact resistance
(mΩ) Initial resistance 2.9 3.5 HTHH 4.6 5.9

As shown in Table 5, the comparative example 7, which was bonded using the anisotropic conductive film of the related art, has a higher contact resistance from the beginning under the severe condition than the direct connection by the soldering, The contact resistance tended to remarkably increase with elapse of time (see Table 5 and Fig. 5). It was also found that Example 2 and Comparative Example 7 exhibited similar properties in terms of adhesive strength.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

10: printed circuit board, 20: solder layer
30: Flexible flat cable, 31: Conductor
40: heat resistant adhesive layer, 50: heat resistant stiffener

Claims (21)

(i) applying a solder cream to one side of a printed circuit board;
(ii) depositing a flexible flat cable on the coated solder cream, exposing a part of the coated conductor in the insulating film of the flexible flat cable and placing it on the solder cream;
(iii) preparing a heat resistant stiffener to which a thermosetting resin adhesive is applied on the first surface;
(iv) stacking the first surface of the heat resistant stiffener coated with the thermosetting adhesive so as to cover the exposed conductor and one area of the flexible flat cable in contact with the conductor; And
(v) a step of pressing the upper surface of the second surface of the heat resistant stiffener to integrally join
And a direct bonding method of a flexible flat cable. The method according to claim 1,
Wherein the printed circuit board of the step (i) comprises a printed circuit board (PCB), which is a metal printed circuit board (MPCB) having a circuit pattern layer and a photo solder resist (PSR) layer for insulating the circuit pattern layer, Connection method. 3. The method of claim 2,
Wherein the step (i) comprises applying a solder cream on the circuit pattern layer, and a direct connection method of the flexible flat cable with the printed circuit board. The method according to claim 1,
The flexible flat cable of step (ii)
(i) a single-sided insulating film in which a plurality of conductors, an adhesive layer and a resin layer are sequentially laminated, or
(ii) a double-sided type insulating film in which an adhesive layer and a resin layer are sequentially laminated on upper and lower surfaces, respectively, with a plurality of conductors as a center, and a direct connection method of the flexible flat cable. 5. The method of claim 4,
Wherein the adhesive layer comprises a polyester-based polymer resin; and a direct connection method of the flexible flat cable with the printed circuit board. 5. The method of claim 4,
Wherein the adhesive layer comprises at least two polyester resins,
Wherein the polyester resin comprises a first polyester resin having a molecular weight of 1,000 to 15,000 and a second polyester resin having a molecular weight of 20,000 to 35,000. 5. The method of claim 4,
Wherein the adhesive layer comprises at least one curing agent,
Wherein the curing agent is a compound containing at least one functional group selected from an isocyanate group, a block isocyanate group, and a carbodiimide group, and a direct connection method of the flexible flat cable to the printed circuit board. 5. The method of claim 4,
Wherein the adhesive layer further comprises at least one flame retardant filler,
Wherein the flame retardant filler is at least one selected from the group consisting of a halogen-free flame retardant, a phosphorus flame retardant, a nitrogen flame retardant, a metal flame retardant, and an antimony flame retardant. The method according to claim 1,
Wherein the heat resistant stiffener in the step (iii) is a polyimide-based film having an extrusion processing temperature of at least 350 캜 or more. The method according to claim 1,
Wherein the thermosetting resin adhesive of the step (iii) is a fast-curing epoxy adhesive having an epoxy resin and a curing agent and having a curing degree of 90% or more within 30 minutes at a temperature of 260 ° C or more, Way. The method according to claim 1,
Wherein the thermosetting resin adhesive of step (iii) is a high heat-resistant adhesive having a glass transition temperature (Tg) in the range of 70 to 100 占 폚. The method according to claim 1,
Wherein the pressing step in the step (iv) is performed by thermocompression for 10 seconds to 5 minutes under a temperature of 260 to 380 ° C and a pressure of 0.1 to 10 MPa. The method according to claim 1,
In the step (iv), the heat generated by the pressing step is conducted from the heat resistant stiffener to the printed circuit board to cure the thermosetting resin adhesive; And the soldering process of the solder cream are performed at the same time. A printed circuit board on one side of which a circuit pattern layer is formed;
A solder layer formed on the circuit pattern layer of the printed circuit board;
A flexible flat cable (FFC) disposed on the printed circuit board and bonded on the solder layer in a state that a part of the coated conductor in the insulation film is exposed;
A thermosetting adhesive layer formed to surround the exposed conductor and a flexible flat cable in contact with the conductor, the thermosetting adhesive layer being strengthened in adhesion to the heat resistant reinforcement; And
A heat-resistant stiffener disposed on the thermosetting adhesive layer
&Lt; / RTI &gt; 15. The method of claim 14,
Wherein the printed circuit board, the flexible flat cable, and the heat-resistant stiffener are a connectorless type connection structure integrated with each other. 20. The method of claim 19,
Wherein the printed circuit board is a part for a display device electrically connected to a light source for generating light and supplying power to the light source. 15. The method of claim 14,
The flexible flat cable is characterized in that the ratio (TH / TR) of the tensile stress (TR) at room temperature to the tensile stress (TH) after holding for 1000 hours under the conditions of a temperature of 85 캜 and a humidity of 85% Power supply. 15. The method of claim 14,
Wherein the flexible flat cable has a contact resistance (? _HTHH ) value of 10 m? _Or less after being maintained at a temperature of 85 DEG C and a humidity of 85% for 500 _hours . 15. The method of claim 14,
Wherein the flexible flat cable has a peel strength value of 1.00 to 5.00 kgf / cm for the printed circuit board after being maintained at a temperature of 85 DEG C and a humidity of 85% for 500 hours. A display device comprising the power supply device of claim 14. 21. The method of claim 20,
A liquid crystal display (LCD), a light emitting diode (LED), a touch panel, a field emission display (FED), a PDA, a plasma display panel (PDP) backlight unit and a light source component.

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