Flexible printed circuit board of double access type and manufacturing method thereof

Abstract

The present invention provides a method for manufacturing a double access type FPCB comprising the steps of: attaching a carrier film to the lower part of a base; irradiating a laser onto the upper part of a base to form a circuit pattern; temporarily attaching a top coverlay to the upper part of the base on which the circuit pattern is formed; removing the carrier film from the lower part of the base; temporarily attaching a bottom coverlay to the lower part of the base from which the carrier film has been removed; and laminating the top coverlay and the bottom coverlay simultaneously using a hot press process.

Description

Technology Field

[0001] The present invention relates to a double access type FPCB and a method for manufacturing the same, and more specifically, to a double access type FPCB using a laser and a method for manufacturing the same. Background Technology

[0003] With the recent advancement of electronic component technology, flexible flat cables (hereinafter referred to as 'FFC') have been used in various fields to reduce the weight and volume of products and to allow for free wiring.

[0004] FFCs are manufactured through a process in which conductors are arranged at regular intervals between the upper and lower layers of an insulating film and laminated using instantaneous heat and pressure. However, there were limitations, such as restricted applicable conductor width and thickness, and the ability to perform only straight-line wiring. Due to this low degree of freedom in circuit design, there was a disadvantage in that it was difficult to expand into various application fields.

[0005] To overcome the limitations of these conventional FFCs, flexible printed circuit boards (hereinafter referred to as 'FPCB') have recently been developed.

[0006] FPCB retains the flexible characteristics of FFC and forms circuit patterns through an etching process, so it has the advantage of having a higher degree of freedom in circuit design than FFC and being able to accommodate narrow line widths of fine circuits, which is expanding into various application fields.

[0007] These FPCBs are classified into three types depending on the number of coverlays. There is a single type in which one coverlay is combined on the top or bottom of the base, a double type in which coverlays are combined on the top and bottom of the base respectively, and a multi-layer type in which multiple coverlays and bases are stacked.

[0008] FIG. 1 is a diagram illustrating the manufacturing process of a conventional double-sided type FPCB, and FIG. 2 is a cross-sectional view of a double-sided type FPCB manufactured by the manufacturing process of FIG. 1.

[0009] Hereinafter, a conventional double-sided FPCB manufacturing process will be described with reference to FIGS. 1 and FIGS. 2.

[0010] First, referring to FIG. 1, a bottom coverlay (20) is temporarily attached to the lower part of the base (10), and then the base (10) and the bottom coverlay (20) are laminated through a hot press process. At this time, the bottom coverlay (20) can be laminated with the base (10) in a processed state in which a hole (21) is pre-formed.

[0011] Next, a circuit pattern (12) and a pattern hole (11) are formed on the base (10) through exposure, development, etching, and stripping steps. Since this step is an exposure or stripping step used in general FPCB steps, a detailed description will be omitted.

[0012] Such etching processes use hazardous chemicals, which poses problems such as environmental pollution.

[0013] Next, a top coverlay (30) is temporarily attached to the top of the base (10), and then the base (10) and the top coverlay (30) are laminated through a hot press process. At this time, the top coverlay (30) can be laminated with the base (10) in a pre-processed state in which a hole (31) is formed.

[0014] Referring to FIG. 2, in a conventional double-sided FPCB, the base (10) and the bottom coverlay (20) are first laminated by melting and curing the adhesive layer (25) of the bottom coverlay (20) using a hot press device.

[0015] Then, the base (10) and the top coverlay (30) are later laminated by melting and curing the adhesive layer (35) of the top coverlay (30) using a hot press device.

[0016] In this way, as the bottom coverlay (20) and the top coverlay (30) are aligned with the base (10), an adhesive layer (35) of the top coverlay (30) is formed in the space area (A) where the pattern hole (11) of the base (10) is formed.

[0017] Accordingly, since the adhesive layer (35) of the top coverlay (30) must be formed with a thickness greater than that of the base (10), manufacturing costs increase, and there is a problem of reduced circuit uniformity due to thickness variation between the space area (A) and other areas. In particular, the thicker the base (10), the more manufacturing costs increase and the lower the circuit uniformity becomes. The problem to be solved

[0019] In order to solve the problems of the prior art as described above, the present invention aims to provide a double access type FPCB capable of forming a circuit pattern on a base using a laser and a method for manufacturing the same.

[0020] In addition, the present invention aims to provide a double access type FPCB and a method for manufacturing the same, which can reduce manufacturing costs by reducing the thickness of the adhesive layer of the top coverlay and the bottom coverlay.

[0021] In addition, the present invention aims to provide a double access type FPCB and a method for manufacturing the same, which can simplify the manufacturing process and improve circuit uniformity by minimizing thickness variation of the FPCB.

[0022] The technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0024] To solve the above problems, the present invention provides a method for manufacturing a double access type FPCB comprising the steps of: attaching a carrier film to the lower part of a base; irradiating a laser onto the upper part of a base to form a circuit pattern; temporarily attaching a top coverlay to the upper part of the base on which the circuit pattern is formed; removing the carrier film from the lower part of the base; temporarily attaching a bottom coverlay to the lower part of the base from which the carrier film has been removed; and laminating the top coverlay and the bottom coverlay simultaneously using a hot press process.

[0025] In addition, the method for manufacturing a double access type FPCB of the present invention may further include the step of forming a first exposure hole that exposes a circuit pattern in the top coverlay prior to the step of temporarily bonding the top coverlay.

[0026] In addition, the method for manufacturing a double access type FPCB of the present invention may further include the step of forming a second exposure hole that exposes a circuit pattern in the bottom coverlay prior to the step of temporarily bonding the bottom coverlay.

[0027] Additionally, the step of simultaneously laminating the top coverlay and the bottom coverlay using a hot press process may include the step of placing a first auxiliary material on the upper part of the top coverlay, the step of placing a second auxiliary material on the lower part of the bottom coverlay, the step of pressurizing and heating the first and second auxiliary materials using a hot press device, and the step of removing the first and second auxiliary materials.

[0028] In addition, the method for manufacturing a double access type FPCB of the present invention may further include the step of forming a first adhesive layer on one surface of a top coverlay that is temporarily attached to the upper part of a base prior to the step of forming a first exposed hole in a top coverlay.

[0029] In addition, the method for manufacturing a double access type FPCB of the present invention may further include the step of forming a second adhesive layer on one surface of a bottom coverlay that is temporarily attached to the lower part of the base prior to the step of forming a second exposed hole in the bottom coverlay.

[0030] Additionally, the step of forming a circuit pattern may include the step of forming a pattern hole on the upper part of the base.

[0031] Additionally, the step of simultaneously laminating the top coverlay and the bottom coverlay by a press process may be a step in which at least a portion of the first adhesive layer and at least a portion of the second adhesive layer are formed in the pattern hole.

[0032] In addition, the method for manufacturing a double access type FPCB of the present invention may further include the step of applying insulating ink to the bottom of the base prior to the step of temporarily attaching a bottom coverlay to the bottom of the base.

[0033] In addition, the present invention provides a double access type FPCB comprising a base including a circuit pattern and a pattern hole, a top coverlay including a first adhesive layer disposed on the upper part of the base, and a bottom coverlay including a second adhesive layer disposed on the lower part of the base, wherein at least a portion of the first adhesive layer and at least a portion of the second adhesive layer are disposed in the pattern hole.

[0034] Here, a first exposure hole that exposes the circuit pattern can be formed in the top coverlay.

[0035] In addition, a second exposure hole that exposes the circuit pattern may be formed in the bottom coverlay. Effects of the invention

[0037] According to the present invention, since a circuit pattern is formed on a base using a laser rather than an etching process, there is an advantage in that harmful chemicals used in the etching process can be omitted.

[0038] In addition, according to the present invention, the thickness of the adhesive layer of the top coverlay and bottom coverlay can be formed to half the thickness of the base, thereby reducing manufacturing costs compared to conventional manufacturing methods.

[0039] In addition, according to the present invention, since the bottom coverlay and the top coverlay are combined with the base simultaneously, the manufacturing process can be simplified, and even if the thickness of the base increases, the thickness variation of the FPCB between the space area where the pattern hole is formed and other areas can be minimized to improve circuit uniformity.

[0040] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0042] Figure 1 is a diagram illustrating the manufacturing process of a conventional double-sided type FPCB. Figure 2 is a cross-sectional view of a double-sided FPCB manufactured by the manufacturing process of Figure 1. FIGS. 3a to 3f are drawings illustrating the manufacturing process of a double access type FPCB according to an embodiment of the present invention. FIG. 4 is a cross-sectional view of a double access type FPCB manufactured by the manufacturing process of FIG. 3a to 3f. Specific details for implementing the invention

[0043] The above-mentioned objectives, means, and resulting effects of the present invention will become clearer through the following detailed description in conjunction with the attached drawings, and accordingly, a person skilled in the art to which the present invention pertains will be able to easily implement the technical concept of the present invention. Furthermore, in describing the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted.

[0044] In this specification, terms such as “or,” “at least one,” etc., may indicate one of the words listed together or a combination of two or more. For example, “A or B” or “at least one of A and B” may include only one of A or B, or may include both A and B.

[0045] In this specification, terms such as 'first,' 'second,' etc., may be used to describe various components, but such components should not be limited by these terms. Furthermore, these terms should not be interpreted as limiting the order of each component, but may be used for the purpose of distinguishing one component from another. For example, 'first component' may be named 'second component,' and similarly, 'second component' may be named 'first component.'

[0047] FIGS. 3a to 3f are drawings illustrating the manufacturing process of a double access type FPCB according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view of a double access type FPCB manufactured by the manufacturing process of FIGS. 3a to 3f.

[0048] Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0049] First, as shown in FIG. 3a, a base (110) is prepared, and a carrier film (140) is attached to the bottom of the base (110).

[0050] The base (110) may be configured by sequentially stacking a lower conductive layer, an insulating layer, and an upper conductive layer. Here, the conductive layer may be made of a conductive metal material such as aluminum (Al) and copper (Cu), and the insulating layer may be made of an insulating material such as a polyamide (PI) film.

[0051] The carrier film (140) may be composed of an adhesive layer and a cushion layer laminated together, and may be attached to the lower part of the base (110) through the adhesive layer.

[0052] The carrier film (140) may be made of a release film. Here, a release film is a type of film used for purposes such as product protection, and is characterized by being easily peelable after being attached to a product.

[0053] For example, the carrier film (140) may be selected from the group consisting of a polymethylpentene film, a modified polybutylene terephthalate film and a polypropylene film.

[0054] Next, as illustrated in FIGS. 3b and 3c, a pattern hole (111) and a circuit pattern (112) are formed in the base (110) using a laser. That is, the circuit pattern (112) can be formed as the laser beam irradiates the upper part of the base (110) to form the pattern hole (111).

[0055] At this time, the carrier film (140) can perform the role of supporting the base (110) when forming the circuit pattern (112) through a laser.

[0056] The laser may be a UV (Ultraviolet) laser. Here, the UV laser has the shortest wavelength among industrial lasers, so the thermal effect of the laser light is low and the absorption rate is high, making it suitable for processing delicate circuit patterns (112).

[0057] As such, the method for manufacturing a double access type FPCB according to an embodiment of the present invention has the advantage of being able to omit harmful chemicals used in the etching process because the circuit pattern (112) is formed on the base (110) using a laser instead of an etching process.

[0058] Next, scrap present on the upper part of the base (110) is removed when forming the pattern hole (111) and circuit pattern (112) using a laser.

[0059] Next, as illustrated in FIG. 3d, a top coverlay (130) is temporarily attached to the top of the base (110) on which the circuit pattern (112) is formed. At this time, the thickness of the top coverlay (130) can be formed to, for example, a thickness of 25 μm.

[0060] The carrier film (140) can serve to support the base (110) and the top coverlay (130) when the top coverlay (130) is temporarily attached.

[0061] As illustrated in FIG. 4, a first adhesive layer (135) may be formed on one side of the top coverlay (130) that is temporarily attached to the upper part of the base (110).

[0062] The top coverlay (130) may be made of a polyamide (PI) film, but is not limited thereto.

[0063] Additionally, the first adhesive layer (135) is formed using an adhesive composition for a coverlay, and can be formed without limitation using a known method capable of forming an adhesive layer of a certain thickness or more on one surface of the top coverlay (130).

[0064] An adhesive composition for a coverlay may be composed of an epoxy resin, a rubber resin, a thermoplastic resin, a curing agent, inorganic particles, and a flame retardant.

[0065] The top coverlay (130) can be pre-processed before being temporarily attached to the base (110). That is, the top coverlay (130) can have a first exposure hole (131) formed in advance to expose the circuit pattern (112) formed on the base (110).

[0066] In this way, since the top coverlay (130) is pre-processed and attached to the base (110), the process of forming the first exposed hole (131) using a UV laser after attachment to the base (110) can be omitted, thereby eliminating quality degradation caused by carbonized material.

[0067] Next, as illustrated in FIG. 3e, the carrier film (140) is removed from the bottom of the base (110). That is, the carrier film (140) has completed its role of supporting the base (110) and the top coverlay (130), and is removed to temporarily attach the bottom coverlay (120) to the bottom of the base (110), which will be described later.

[0068] At this time, as described above, since the carrier film (140) is made of a release film, it can be easily peeled off from the base (110).

[0069] Next, as shown in FIG. 3f, a bottom coverlay (120) is temporarily attached to the bottom of the base (110) from which the carrier film (140) has been removed. At this time, the thickness of the bottom coverlay (120) can be formed to be the same thickness as the top coverlay (120), for example, 25 μm.

[0070] As shown in FIG. 4, a second adhesive layer (125) may be formed on one side of the bottom coverlay (120) that is temporarily attached to the lower part of the base (110).

[0071] The bottom coverlay (120) may be made of a polyamide (PI) film, but is not limited thereto.

[0072] Additionally, the second adhesive layer (125) is formed using an adhesive composition for a coverlay, and can be formed without limitation using a known method capable of forming an adhesive layer of a certain thickness or more on one surface of the bottom coverlay (120).

[0073] The adhesive composition for coverlay may include an epoxy resin, a rubber resin, a thermoplastic resin, a curing agent, inorganic particles, and a flame retardant.

[0074] The bottom coverlay (120) can be pre-processed before being temporarily attached to the base (110). That is, the bottom coverlay (120) can have a second exposure hole (121) formed in advance to expose the circuit pattern (112) formed on the base (110).

[0075] In this way, since the bottom coverlay (120) is pre-processed and attached to the base (110), the process of forming the second exposed hole (121) using a UV laser after attachment to the base (110) can be omitted, thereby eliminating quality degradation caused by carbonized material.

[0076] Next, the top coverlay (130) and the bottom coverlay (120) are laminated simultaneously using a hot press process. Accordingly, a double access type FPCB according to an embodiment of the present invention is completed as shown in FIG. 4.

[0077] Specifically, in the hot press process, a first auxiliary material is placed on the top coverlay (130) and a second auxiliary material is placed on the bottom coverlay (120) to assist in heating and pressurizing the hot press device. Here, the first and second auxiliary materials may be made of Kraft paper, Sus plate, PVC, etc.

[0078] Next, the first and second auxiliary materials are simultaneously pressurized and heated using a hot press device. Accordingly, the first adhesive layer (135) of the top coverlay (130) and the second adhesive layer (125) of the bottom coverlay (120) are simultaneously melted and cured, thereby laminating the bottom coverlay (120), base (110), and top coverlay (130).

[0079] At this time, the first adhesive layer (135) of the top coverlay (130) and the second adhesive layer (125) of the bottom coverlay (120) are simultaneously melted and flowed into the space area (A) where the pattern hole (111) of the base (110) is formed and cured.

[0080] Accordingly, the first adhesive layer (135) of the top coverlay (130) and the second adhesive layer (125) of the bottom coverlay (120) are placed together inside the pattern hole (111). That is, at least a portion of the first adhesive layer (135) and at least a portion of the second adhesive layer (125) are formed in the pattern hole (111).

[0081] For example, if the thickness of the base (110) is 70 μm, the thickness of the first adhesive layer (135) between the base (110) and the top coverlay (130) and the thickness of the second adhesive layer (125) between the base (110) and the bottom coverlay (120) can be formed to be 40 μm, and the first adhesive layer (135) and the second adhesive layer (125) can each be formed to be 35 μm, which is half the thickness of the base (110), inside the pattern hole (111).

[0082] Accordingly, the manufacturing method of a double access type FPCB according to an embodiment of the present invention allows the bottom coverlay (120) and the top coverlay (130) to be combined with the base (110) simultaneously, thereby allowing the thickness of the first adhesive (135) of the top coverlay (130) and the second adhesive (125) of the bottom coverlay (120) to be formed to half the thickness of the base (110), thus reducing manufacturing costs compared to conventional manufacturing methods.

[0083] In addition, the manufacturing method of a double access type FPCB according to an embodiment of the present invention can simplify the manufacturing process as the bottom coverlay (120) and the top coverlay (130) are combined with the base (110) simultaneously, and can improve circuit uniformity by minimizing the thickness variation of the FPCB between the space area (A) where the pattern hole (111) is formed and other areas, even if the thickness of the base (110) increases.

[0084] Meanwhile, the method for manufacturing a double access type FPCB according to an embodiment of the present invention may apply insulating ink to the bottom of the base (110) before attaching a bottom coverlay (120) to the bottom of the base (110).

[0085] At this time, the insulating ink applied to the base (110) may have a step difference between the space area (A) where the pattern hole (111) is formed and the area other than the space area.

[0086] A method for manufacturing a double access type FPCB according to an embodiment of the present invention can eliminate the insulating ink step difference between the space area (A) where the pattern hole (111) is formed and other areas by simultaneously aligning the bottom coverlay (120) and the top coverlay (130) with the base (110).

[0088] Hereinafter, with reference to FIG. 4, a double access type FPCB according to an embodiment of the present invention will be described.

[0089] A double access type FPCB according to an embodiment of the present invention may be configured to include a base (110), a top coverlay (130), and a bottom coverlay (120).

[0090] The base (110) may include a circuit pattern (112) and a pattern hole (111). Here, the circuit pattern (112) and the pattern hole (111) may be formed using a UV laser.

[0091] As such, the double access type FPCB according to the embodiment of the present invention has the advantage of being able to omit harmful chemicals used in the etching process because it forms a circuit pattern (112) on the base (110) using a laser instead of an etching process.

[0092] The top coverlay (130) includes a first adhesive layer (135) and can be placed on top of the base (110). That is, the top coverlay (130) can be laminated with the base (110) through the first adhesive layer (135).

[0093] Additionally, the top coverlay (130) may have a first exposure hole (135) formed therein to expose the circuit pattern.

[0094] The bottom coverlay (120) includes a second adhesive layer (125) and can be placed on the lower part of the base (110). That is, the bottom coverlay (120) can be laminated with the base (110) through the second adhesive layer (125).

[0095] The bottom coverlay (120) may have a second exposure hole formed therein to expose the circuit pattern.

[0096] Here, the bottom coverlay (120) and the top coverlay (130) can be combined with the base (110) at the same time.

[0097] Accordingly, the double access type FPCB according to an embodiment of the present invention is characterized in that at least a portion of the first adhesive layer (135) and at least a portion of the second adhesive layer (125) are disposed in the pattern hole (111) of the base (110).

[0098] Due to these features, the double access type FPCB according to the embodiment of the present invention can reduce manufacturing costs compared to conventional manufacturing methods by forming the thickness of the first adhesive (135) of the top cover layer (130) and the second adhesive (125) of the bottom cover layer (120) to half the thickness of the base (110) as the bottom cover layer (120) and the top cover layer (130) are combined simultaneously with the base (110).

[0099] In addition, the double access type FPCB according to the embodiment of the present invention can simplify the manufacturing process as the bottom coverlay (120) and the top coverlay (130) are simultaneously combined with the base (110), and can improve circuit uniformity by minimizing the thickness variation of the FPCB between the space area (A) where the pattern hole (111) is formed and other areas, even if the thickness of the base (110) increases.

[0101] Although specific embodiments have been described in the detailed description of the present invention, it is understood that various modifications are possible within the scope of the invention. Therefore, the scope of the present invention is not limited to the described embodiments and should be defined by the claims set forth below and equivalents thereof. Explanation of the symbols

[0103] 110: Bass 111: Circuit pattern 112: Pattern Hole 120: Bottom Coverlay 121: Second exposure hole 125: Second adhesive layer 130: Top Coverlay 131: Second exposure hole 135: First adhesive layer

Claims

Claim 1 A method for manufacturing a double access type FPCB comprising: a step of attaching a carrier film to the lower part of a base; a step of forming a circuit pattern by irradiating a laser onto the upper part of the base; a step of temporarily attaching a top coverlay to the upper part of the base on which the circuit pattern is formed; a step of removing the carrier film from the lower part of the base; a step of temporarily attaching a bottom coverlay to the lower part of the base from which the carrier film has been removed; and a step of simultaneously laminating the top coverlay and the bottom coverlay using a hot press process. Claim 2 A method for manufacturing a double access type FPCB according to claim 1, further comprising the step of forming a first exposure hole that exposes the circuit pattern in the top coverlay prior to the step of temporarily bonding the top coverlay. Claim 3 A method for manufacturing a double access type FPCB according to claim 2, further comprising the step of forming a second exposure hole that exposes the circuit pattern in the bottom coverlay prior to the step of temporarily bonding the bottom coverlay. Claim 4 A method for manufacturing a double access type FPCB according to claim 1, wherein the step of simultaneously laminating the top coverlay and the bottom coverlay by a hot press process comprises: a step of placing a first auxiliary material on the upper part of the top coverlay; a step of placing a second auxiliary material on the lower part of the bottom coverlay; a step of applying pressure and heating the first and second auxiliary materials using a hot press device; and a step of removing the first and second auxiliary materials. Claim 5 A method for manufacturing a double access type FPCB according to claim 3, further comprising the step of forming a first adhesive layer on one surface of the top coverlay that is temporarily attached to the upper part of the base prior to the step of forming the first exposed hole in the top coverlay. Claim 6 A method for manufacturing a double access type FPCB according to claim 5, further comprising the step of forming a second adhesive layer on one surface of the bottom coverlay that is temporarily attached to the lower part of the base prior to the step of forming the second exposed hole in the bottom coverlay. Claim 7 A method for manufacturing a double access type FPCB according to claim 6, wherein the step of forming the circuit pattern includes the step of forming a pattern hole on the upper part of the base. Claim 8 A method for manufacturing a double access type FPCB according to claim 7, wherein the step of simultaneously laminating the top coverlay and the bottom coverlay by a press process is a step in which at least a portion of the first adhesive layer and at least a portion of the second adhesive layer are formed in the pattern hole. Claim 9 A method for manufacturing a double access type FPCB according to claim 1, further comprising the step of applying insulating ink to the lower part of the base prior to the step of temporarily attaching a bottom coverlay to the lower part of the base. Claim 10 delete Claim 11 delete Claim 12 delete

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