KR20240041648A - Flexible printed circuit board, cof module and electronic device comprising the same - Google Patents

Abstract

A flexible printed circuit board according to an embodiment includes a substrate including a chip mounting area; and a circuit pattern disposed on the substrate, wherein the circuit pattern includes a first circuit pattern, a second circuit pattern, and a third circuit pattern, and the first circuit pattern is disposed inside the chip mounting area. It includes a first pad part, a second pad part disposed outside the chip mounting area, and a first wiring part connected to the first pad part and the second pad part, and the second circuit pattern is located in the chip mounting area. A third pad portion disposed inside, a fourth pad portion disposed outside the chip mounting area, and a second wiring portion connected to the third pad portion and the fourth pad portion, and the third circuit pattern. includes a third wiring portion and a fifth pad portion disposed inside the chip mounting area, and the width of the third wiring portion is greater than the width of the fifth pad portion.

Description

Flexible printed circuit board, COF module, and electronic device including the same {FLEXIBLE PRINTED CIRCUIT BOARD, COF MODULE AND ELECTRONIC DEVICE COMPRISING THE SAME}

The embodiment relates to a flexible printed circuit board, a COF module, and an electronic device including the same. In detail, the flexible printed circuit board may be a flexible printed circuit board for COF.

Recently, various electronic products are becoming thinner, smaller, and lighter. Accordingly, various researches are being conducted to mount semiconductor chips at high density in narrow areas of electronic products.

Among them, the COF (Chip On Film) method uses a flexible substrate, so it can be applied to flexible displays. In other words, the COF method is attracting attention because it can be applied to various wearable electronic devices. Additionally, because the COF method can implement a fine pitch, it can be used to implement a high-resolution display as the number of pixels increases.

COF (Chip On Film) is a method of mounting a semiconductor chip on a thin film-shaped flexible printed circuit board. For example, a semiconductor chip may be an integrated circuit (IC) chip or a large scale integrated circuit (LSI) chip.

The chip can be connected to an external PCB and display panel through a circuit pattern. For example, pad portions may be disposed on one end and the other end of the circuit pattern, one pad portion may be electrically connected to a terminal of the chip, and the other pad portion may be connected to a terminal of the PCB and the display panel. Accordingly, the chip, PCB, and display panel are electrically connected through the COF, and signals can be transmitted to the display panel through the circuit pattern.

Meanwhile, chips mounted on the flexible printed circuit board may be arranged in a multi-layer structure that performs each role.

Recently, FLR (Film Level Route) technology, which places one of these multi-layered chips and a circuit pattern connected to it directly on a flexible printed circuit board, has been applied. That is, by arranging the routing pattern in the chip mounting area of the flexible printed circuit board, the size of the layer structure of the chip can be reduced, thereby reducing the manufacturing cost of the chip.

Meanwhile, the process of bonding the routing pattern and the chip is performed at high temperature and pressure. Accordingly, stress is generated during the process, and this stress may be transmitted to the routing pattern. Accordingly, there is a problem in that cracks occur in one area of the routing pattern and the reliability of the COF module is reduced.

Therefore, there is a need for flexible printed circuit boards, COF modules, and electronic devices containing the same with new structures that can solve the above problems.

As a patent related to the flexible printed circuit board, Korean registered patent KR10-0618898 (2006.09.01) is disclosed.

The embodiment seeks to provide a flexible printed circuit board that can secure reliability by preventing cracks in the routing pattern and has improved electrical characteristics, and a COF module including the same.

A flexible printed circuit board according to an embodiment includes a substrate including a chip mounting area; and a circuit pattern disposed on the substrate, wherein the circuit pattern includes a first circuit pattern, a second circuit pattern, and a third circuit pattern, and the first circuit pattern is disposed inside the chip mounting area. It includes a first pad part, a second pad part disposed outside the chip mounting area, and a first wiring part connected to the first pad part and the second pad part, and the second circuit pattern is located in the chip mounting area. A third pad portion disposed inside, a fourth pad portion disposed outside the chip mounting area, and a second wiring portion connected to the third pad portion and the fourth pad portion, and the third circuit pattern. includes a third wiring portion and a fifth pad portion disposed inside the chip mounting area, and the width of the third wiring portion is greater than the width of the fifth pad portion.

In the flexible printed circuit board according to the embodiment, the width of the third circuit pattern (routing pattern) disposed in the chip mounting area can be formed in various sizes. Accordingly, it is possible to prevent the third circuit pattern from being damaged or deformed due to stress generated when bonding the chip and the third circuit pattern.

Additionally, the stress generated when bonding the chip and the third circuit pattern may vary from location to location. Accordingly, the width of the wiring portion of the third circuit pattern can be varied at each location. Accordingly, the third circuit pattern can be prevented from being damaged or deformed.

Accordingly, the flexible printed circuit board according to the embodiment and the COF module including the same can be manufactured in a small size and have improved electrical characteristics.

Figure 1 is a top view of a COF module including a flexible printed circuit board according to an embodiment.
FIG. 2 is a diagram for explaining area A of FIG. 1.
Figures 3 and 4 are cross-sectional views taken along area AA' of Figure 2.
FIG. 5 is an enlarged view of area B of FIG. 2.
FIG. 6 is a diagram for explaining various shapes of area C of FIG. 3.
FIG. 7 is another diagram for explaining area A of FIG. 1.
FIG. 8 is an enlarged view of area D of FIG. 7.
FIG. 9 is another diagram for explaining area A of FIG. 1.
FIG. 10 is an enlarged view of area E of FIG. 9.
FIG. 11 is another diagram for explaining area A of FIG. 1.
FIG. 12 is an enlarged view of area F in FIG. 11.
FIG. 13 is another diagram for explaining area A of FIG. 1.
FIG. 14 is a cross-sectional view taken along area BB' of FIG. 13.
Figure 15 is a top view of a COF module according to an embodiment.
Figure 16 is a cross-sectional view showing the connection relationship of a COF module including a flexible printed circuit board according to an embodiment.
17 to 19 are diagrams of electronic devices including a flexible printed circuit board according to an embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical idea of the present invention is not limited to some of the described embodiments, but may be implemented in various different forms, and as long as it is within the scope of the technical idea of the present invention, one or more of the components may be optionally used between the embodiments. It can be used by combining and replacing.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention, unless explicitly specifically defined and described, are generally understood by those skilled in the art to which the present invention pertains. It can be interpreted as meaning, and the meaning of commonly used terms, such as terms defined in a dictionary, can be interpreted by considering the contextual meaning of the related technology.

Additionally, the terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention. In this specification, the singular may also include the plural unless specifically stated in the phrase, and when described as “at least one (or more than one) of A, B, and C,” it can be combined with A, B, and C. It can contain one or more of all possible combinations.

Additionally, when describing the components of an embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and are not limited to the essence, sequence, or order of the component.

And, when a component is described as being 'connected', 'coupled' or 'connected' to another component, the component is not only directly connected, coupled or connected to the other component, but also is connected to the other component. It may also include cases where other components are 'connected', 'coupled', or 'connected' by another component between them.

Additionally, when described as being formed or disposed "above" or "below" each component, "above" or "below" refers not only to cases where two components are in direct contact with each other, but also to one This also includes cases where another component described above is formed or placed between two components.

Additionally, when expressed as “top (above) or bottom (bottom),” it can include the meaning of not only the upward direction but also the downward direction based on one component.

Hereinafter, a flexible printed circuit board, a COF module, and an electronic device including the same according to an embodiment will be described with reference to the drawings.

1 is a top view of a flexible printed circuit board according to an embodiment.

Referring to FIG. 1, a flexible printed circuit board 1000 according to an embodiment includes a substrate 100, a circuit pattern 200 disposed on the substrate 100, and a protective layer disposed on the circuit pattern 200 ( 300).

The substrate 100 may include a flexible substrate. For example, the substrate 100 may be a polyimide (PI) substrate. However, the embodiment is not limited to this, and the substrate 100 may include a polymer material such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). Accordingly, the flexible printed circuit board can be used in various electronic devices equipped with a curved display device. For example, since the flexible printed circuit board has excellent flexible characteristics, it may be suitable for mounting semiconductor chips of wearable electronic devices.

The substrate 100 may have a thickness of 20㎛ to 100㎛. For example, the substrate 100 may have a thickness of 25 μm to 50 μm. For example, the substrate 100 may have a thickness of 30㎛ to 40㎛. If the thickness of the substrate 100 exceeds 100㎛, the overall thickness of the flexible printed circuit board may increase. As a result, the flexible characteristics of the flexible circuit board may be reduced. Additionally, if the thickness of the substrate 100 is less than 20㎛, the substrate may be damaged by heat/pressure applied to the substrate 100 when mounting a chip on a flexible printed circuit board.

The substrate 100 may include an effective area (UA) and an unactive area (UA). For example, the effective area (AA) may be a central area of the substrate 100, and the unactive area (UA) may be an edge area of the substrate 100.

The effective area (AA) may include a chip mounting area (CA). In detail, the effective area AA may include a chip mounting area CA where a chip connected to the circuit pattern is mounted. The protective layer 300 is not disposed in the chip mounting area CA. Accordingly, the pad portion of the circuit pattern disposed in the chip mounting area CA may be exposed, and the pad portion of the circuit pattern may be connected to the terminal portion of the chip.

A plurality of circuit patterns 210, 220, and 230 may be disposed on the effective area AA. In detail, a plurality of circuit patterns that are spaced apart from each other and extend in multiple directions may be disposed in the effective area AA.

The effective area AA may be an area actually used in the flexible printed circuit board 1000. That is, when the flexible printed circuit board is in contact with another panel, etc., the effective area AA may be an area in contact with the panel.

The circuit pattern may not be disposed in the unactive area (UA). That is, the active area (AA) and the unactive area (UA) can be distinguished depending on whether or not the circuit pattern is arranged.

The unactive area (UA) may include a plurality of holes. In detail, the unactive area (UA) may include a plurality of sprocket holes (H). The flexible printed circuit board can be wound or unwound in a roll-to-roll manner by the sprocket hole (H).

The unavailable area (UA) may be an area that is not actually used in the flexible printed circuit board 1000. That is, the non-effective area (UA) may be an area that is removed when the flexible printed circuit board is in contact with another panel, etc.

In detail, the flexible printed circuit board 1000 is processed into a COF module after cutting a cutting line (CL) defined as the boundary between the unactive area (UA) where the sprocket hole (H) is formed and the effective area (AA). It can be mounted on various electronic devices.

The circuit pattern may include a wiring portion and a pad portion. Additionally, a plurality of circuit patterns may be disposed in the effective area AA. The circuit pattern may include a first circuit pattern 210, a second circuit pattern 220, and a third circuit pattern 230.

In detail, the first circuit pattern 210 and the second circuit pattern 220 may be disposed inside the chip mounting area CA and outside the chip mounting area CA. Additionally, the third circuit pattern 230 may be disposed inside the chip mounting area CA.

Referring to FIGS. 1 and 2 , the first circuit pattern 210 may include a first wiring portion 211, a first pad portion 212a, and a second pad portion 212b. In detail, the first circuit pattern 210 includes the first pad portion 212a disposed inside the chip mounting area CA, and the second pad portion 212b disposed outside the chip mounting area CA. and a first wiring portion 211 disposed between the first pad portion 212a and the second pad portion 212b and connected to the first pad portion 212a and the second pad portion 212b. may include.

The first wiring portion 211, the first pad portion 212a, and the second pad portion 212b may be formed integrally.

Additionally, the first wiring unit 211 may be arranged to extend in the first direction 1D based on the chip mounting area CA.

The first pad portion 212a may be electrically connected to a chip disposed in the chip mounting area. Additionally, the second pad portion 212b may be electrically connected to the printed circuit board. Additionally, the first wiring unit 211 may transmit signals between the chip and the printed circuit board.

A protective layer 300 may be disposed on the first circuit pattern 210 . In detail, the protective layer 300 may be disposed on the first wiring portion 211. The protective layer 300 may be disposed surrounding the first wiring portion 211 . Additionally, the protective layer 300 may not be disposed on the first pad portion 212a and the second pad portion 212b. Accordingly, the first pad portion 212a and the second pad portion 212b may be exposed to the outside.

Additionally, the second circuit pattern 220 may include a second wiring portion 221, a third pad portion 222a, and a fourth pad portion 222b. In detail, the second circuit pattern 220 includes the third pad portion 222a disposed inside the chip mounting area CA, and the fourth pad portion 222b disposed outside the chip mounting area CA. and a second wiring portion 221 disposed between the third pad portion 222a and the fourth pad portion 222b and connected to the third pad portion 222a and the fourth pad portion 222b. may include.

The second wiring portion 221, the third pad portion 222a, and the fourth pad portion 222b may be formed integrally.

Additionally, the second wiring unit 221 may be arranged to extend in the second direction D2 based on the chip mounting area CA. In detail, the second wiring unit 221 may be arranged to extend in a second direction 2D, which is opposite to the first direction D1.

The third pad portion 222a may be electrically connected to a chip disposed in the chip mounting area. Additionally, the fourth pad portion 222b may be electrically connected to the display panel. Additionally, the second wiring unit 221 may transmit signals between the chip and the display panel.

A protective layer 300 may be disposed on the second circuit pattern 220. In detail, the protective layer 300 may be disposed on the second wiring portion 221. The protective layer 300 may be disposed surrounding the second wiring portion 221 . Additionally, the protective layer 300 may not be disposed on the third pad portion 222a and the fourth pad portion 222b. Accordingly, the third pad portion 222a and the fourth pad portion 222b may be exposed to the outside.

The third circuit pattern 230 may include a third wiring portion 231 and a plurality of fifth pad portions 232. In detail, the third circuit pattern 230 may include a third wiring portion 231 and a plurality of fifth pad portions 232 disposed inside the chip mounting area CA.

The third circuit pattern 230 may be connected to a chip disposed in the chip mounting area CA. In detail, the plurality of fifth pad portions 232 may be electrically connected to the chip. In detail, the third circuit pattern 230 may include a plurality of third circuit patterns 230, each of the third circuit patterns 230 includes at least one fifth pad portion, and each 5 The pad portion may be electrically connected to the chip.

The third circuit pattern 230 may be a routing pattern. The third circuit pattern 230 may be a film level route (FLR) pattern. The third circuit pattern 230 may be a routing pattern that serves as one layer among the layers of a chip having a plurality of layers disposed in the chip mounting area CA.

Since the third circuit pattern 230 is connected to the chip through the plurality of fifth pad portions, it can receive and process the electronic signal transmitted from the first circuit pattern 210. Additionally, an electronic signal transmitted from the third circuit pattern 230 through the chip and the second circuit pattern 220 may be transmitted to the display panel.

At least one of the first circuit pattern 210, the second circuit pattern 220, and the third circuit pattern 230 may include a metal material with excellent electrical conductivity. In detail, at least one circuit pattern among the first circuit pattern 210, the second circuit pattern 220, and the third circuit pattern 230 may include copper (Cu).

However, the embodiment is not limited to this, and at least one circuit pattern among the first circuit pattern 210, the second circuit pattern 220, and the third circuit pattern 230 is copper (Cu), aluminum ( Al), chromium (Cr), nickel (Ni), silver (Ag), molybdenum (Mo). It may include at least one metal selected from gold (Au), titanium (Ti), and alloys thereof.

Hereinafter, with reference to FIGS. 3 and 4, the layer structure of the circuit pattern of the flexible printed circuit board according to the embodiment will be described. The description of the layer structure described in FIGS. 3 and 4 may be applied to at least one circuit pattern among the first circuit pattern 210, the second circuit pattern 220, and the third circuit pattern 230. For convenience of explanation, the following description will focus on the first circuit pattern.

Referring to FIG. 3, the first circuit pattern 210 may be formed in multiple layers. In detail, the first wiring part 211 and the first pad part 212a may include a first metal layer 201 and a second metal layer 202. Also, although not shown in Figure 3. The second pad portion 212b may also include the first metal layer 201 and the second metal layer 202.

The first metal layer 201 may be a seed layer of the first circuit pattern 210. In detail, the first metal layer 201 may be a seed layer formed on the substrate 100 through electroless plating using a metal material such as copper (Cu).

Additionally, the second metal layer 202 may be a plating layer. In detail, the second metal layer 202 may be a plating layer formed by electroplating using the first metal layer 201 as a seed layer.

The thickness of the first metal layer 201 may be smaller than the thickness of the second metal layer 202.

For example, the first metal layer 201 may have a thickness of 0.7 μm to 2 μm, and the second metal layer 202 may have a thickness of 10 μm to 25 μm.

The first metal layer 201 and the second metal layer 202 may include the same metal material. For example, the first metal layer 201 and the second metal layer 202 may include copper (Cu).

Additionally, a bonding layer 203 may be disposed on the second metal layer 201. In detail, the bonding layer 203 may be disposed on the sides of the first metal layer 201 and the second metal layer 202, and on the top surface of the second metal layer 202. That is, the bonding layer 203 may be disposed surrounding the first metal layer 201 and the second metal layer 202.

The bonding layer 203 may include metal. In detail, the bonding layer 203 may include tin (Sn).

The bonding layer 203 may be formed to have a thickness of 0.3 ㎛ to 0.7 ㎛. The bonding layer 203 may have an increased tin content as it extends from the lower surface where the bonding layer 203 and the second metal layer 202 are in contact with the upper surface.

That is, since the bonding layer 203 is disposed in contact with the second metal layer 202, the tin content may increase and the copper content may decrease as it moves from the lower surface to the upper surface of the bonding layer 203. .

Accordingly, only pure tin may remain in the upper surface of the bonding layer 203 in a thickness range of 0.1 ㎛ to 0.3 ㎛.

The bonding layer 203 allows the terminals of the chip, the printed circuit board, and the display panel to be easily bonded to the pad portion through heat and pressure. That is, when heat and pressure are applied to the pad portion, the upper surface where pure tin remains in the bonding layer is melted and can be easily bonded to the terminals of the chip, the printed circuit board, and the display panel.

Accordingly, the bonding layer 203 is not separated from the first pad portion 212a and can become a part of the first pad portion 212a.

The first circuit pattern 210 may be arranged to have a thickness of 2㎛ to 25㎛. For example, the first circuit pattern 210 may be arranged to have a thickness of 5 μm to 20 μm. For example, the first circuit pattern 210 may be arranged to have a thickness of 7㎛ to 15㎛.

Since the first circuit pattern 210 undergoes a process of etching the first metal layer 201 by flash etching, which is performed to separate the circuit patterns during the manufacturing process, the first circuit that is finally manufactured is The pattern 210 may be smaller than the sum of the thicknesses of the first metal layer 201, the second metal layer 202, and the bonding layer 203 formed during the manufacturing process.

When the thickness of the first circuit pattern 210 is less than 2㎛, the resistance of the first circuit pattern 210 may increase. If the thickness of the first circuit pattern 210 exceeds 25㎛, it may be difficult to implement a fine pattern.

Meanwhile, a buffer layer 205 may be further disposed between the substrate 100 and the first circuit pattern 210. The buffer layer 205 can improve adhesion between the substrate 100, which is a dissimilar material, and the first circuit pattern 210.

The buffer layer 205 may be formed of multiple layers. In detail, a first buffer layer 205a and a second buffer layer 205b on the first buffer layer 205a may be disposed on the substrate 100. Accordingly, the first buffer layer 205a may be disposed in contact with the substrate 100, and the second buffer layer 205b may be disposed in contact with the first circuit pattern 210.

The first buffer layer 205a may include a material that has good adhesion to the substrate 100. For example, the first buffer layer 205a may include nickel (Ni). Additionally, the second buffer layer 205b may include a material that has good adhesion to the first circuit pattern 210. For example, the second buffer layer 205b may include chromium (Cr).

The buffer layer 205 including the first buffer layer 205a and the second buffer layer 205b may have a thin film thickness in nanometer units. For example, the buffer layer 205 may have a thickness of 20 nm or less.

The buffer layer 205 can improve adhesion between the substrate 100, which is a dissimilar material, and the first circuit pattern 210, thereby preventing delamination of the first circuit pattern 201.

Alternatively, referring to FIG. 4, unlike FIG. 3, the bonding layer 203 may include a plurality of bonding layers. For example, the bonding layer 203 may include a first bonding layer 203a and a second bonding layer 203b.

In detail, the first bonding layer 203a may be disposed on the first wiring portion 211 and the first pad portion 212a. Additionally, although not shown in the drawing, the first bonding layer 203a may also be disposed on the second pad portion 212b. That is, the first bonding layer 203a may be disposed on the first circuit pattern 210.

Additionally, the second bonding layer 203b may be disposed only on the first pad portion 212a and the second pad portion 212b. That is, the first wiring portion 211, the first pad portion 212a, and the second pad portion 212b may have different layer structures due to the second bonding layer 203b.

The first bonding layer 203a and the second bonding layer 203b may include metal. In detail, the first bonding layer 203a and the second bonding layer 203b may include tin (Sn).

The first bonding layer 203a and the second bonding layer 203b may be disposed at different thicknesses. In detail, the second bonding layer 203b may be greater than the thickness of the first bonding layer 203a.

For example, the first bonding layer 203a may have a thin film thickness of 0.02 μm to 0.06 μm, and the second bonding layer 203b may have a thickness of 0.2 μm to 0.6 μm.

If the bonding layer is thickly disposed between the protective layer 300 and the first wiring portion 211, cracks may occur when the flexible printed circuit board is bent. Accordingly, the first bonding layer 231 between the protective layer 300 and the first wiring portion 211 is formed to have a thin film thickness, thereby preventing cracks from occurring when bending the flexible printed circuit board. there is.

Additionally, the tin content of the second bonding layer 203b may increase as it extends from the lower surface where the second bonding layer 203b and the first bonding layer 203a contact the upper surface.

That is, the tin content of the second bonding layer 203b may increase and the copper content may decrease as it moves from the lower surface to the upper surface of the second bonding layer 203b.

Accordingly, only pure tin may remain in the upper surface of the second bonding layer 203b in a thickness range of 0.1 μm to 0.3 μm.

By using the second bonding layer 203b, the terminals of the chip, the printed circuit board, and the display panel can be easily bonded to the pad portion through heat and pressure. That is, when heat and pressure are applied to the pad portion, the upper surface where pure tin remains in the bonding layer is melted and can be easily bonded to the terminals of the chip, the printed circuit board, and the display panel.

Accordingly, the first bonding layer 203a and the second bonding layer 203b are not separated from the first pad portion 212a and may be a part of the first pad portion 212a.

The protective layer 300 may be disposed on wiring portions of the first circuit pattern 210 and the second circuit pattern 220 . In detail, the protective layer 300 may be arranged to surround the first wiring portion 211 and the second wiring portion 221. That is, the protective layer 300 is formed on the area of the first circuit pattern 210 and the second circuit pattern 220 excluding the first pad part, the second pad part, the third pad part, and the fourth pad part. can be placed in

The protective layer 300 may include solder paste. For example, the protective layer 300 may include a solder paste containing a thermosetting resin, a thermoplastic resin, a filler, a curing agent, or a curing accelerator.

Meanwhile, in the previous description, it was described that the first circuit pattern 210 and the second circuit pattern 220 are disposed on the same surface of the substrate 100, but the embodiment is not limited thereto.

In detail, the first circuit pattern 210 and the second circuit pattern 220 may be disposed on different surfaces of the substrate 100. For example, the first circuit pattern 210 may be disposed on one side of the substrate 100, and the second circuit pattern 220 may be disposed on the other side opposite to one side of the substrate 100. there is.

Accordingly, the display panel may be connected to the chip on one side of the substrate 100, and the printed circuit board may be connected to the chip on the other side of the substrate 100.

Meanwhile, as described above, the third circuit pattern 230 is disposed inside the chip mounting area CA.

The chip and pad portions of the first circuit pattern, the second circuit pattern, and the third circuit pattern may be bonded in a high temperature and high pressure environment. Therefore, when bonding the pad portion of the chip and the circuit pattern, stress may occur due to high temperature and high pressure.

A protective layer is disposed on the wiring portions of the first circuit pattern and the second circuit pattern that are disposed outside the chip mounting area. Accordingly, during the bonding process, the wiring portions of the first circuit pattern and the second circuit pattern Even if stress is transmitted, deformation or cracking of the first circuit pattern and the second circuit pattern can be prevented.

However, a protective layer is not disposed on the third circuit pattern disposed inside the chip mounting area. Accordingly, during the bonding process, the stress is transferred to the wiring portion of the third circuit pattern, and deformation or cracking of the third circuit pattern due to this stress can be prevented.

Accordingly, as the shape of the third circuit pattern changes, adjacent third circuit patterns may contact and short-circuit each other. Alternatively, a crack may occur in one area of the third circuit pattern, thereby reducing the electrical characteristics of the COF module.

Below, a flexible printed circuit board and COF module that can solve the above problems will be described.

Referring to FIGS. 2, 5, and 6, the third circuit pattern 230 may include regions of different sizes. In detail, the third circuit pattern 230 may include regions with different widths. In detail, the third circuit pattern 230 may have a width (w1) of the third wiring portion 231 and a width (w2) of the fifth pad portion 232 that are different from each other.

The width w1 of the third wiring part 231 may be larger than the width w2 of the fifth pad part 232. Here, the width w1 of the third wiring part 231 is defined as the maximum width of the third wiring part, and the width w2 of the fifth pad part 232 is the width of the fifth pad part 232. It is defined as the maximum width.

The terminal portion 400 of the chip may be disposed on the fifth pad portion 232. Since the width (w2) of the fifth pad portion 232 is smaller than the width (w1) of the third wiring portion 231, the spacing between the third circuit patterns 230 increases due to the terminal portion 400. You can prevent it from happening. Accordingly, it is possible to prevent the size of the flexible printed circuit board from increasing. Additionally, the number of third circuit patterns disposed in the chip mounting area CA may increase.

Since the width w1 of the third wiring part 231 is larger than the width w2 of the fifth pad part 232, when the fifth pad part 232 and the terminal part 400 are bonded, the Damage to the third wiring unit 231 can be prevented. In detail, the fifth pad portion 232 and the terminal portion 400 are bonded at high temperature and high pressure. As a result, stress is generated during the bonding process, and this stress moves in the direction of the third wiring portion 231.

In an embodiment, the width w1 of the third wiring part 231 may be increased than the width w2 of the fifth pad part 232, thereby increasing the strength of the third wiring part 231. In detail, since the width w1 of the third wiring portion 231 increases, the area of the third wiring portion 231 increases. Accordingly, the magnitude of stress per unit area in the third wiring portion 231 may be reduced. Accordingly, it is possible to prevent the shape of the third wiring portion 231 from changing or cracks from occurring due to the stress.

For example, the width w1 of the third wiring part 231 may be three times or less than the width w2 of the fifth pad part 232. In detail, the width w1 of the third wiring part 231 may be more than 1 to 3 times the width w2 of the fifth pad part 232. In more detail, the width w1 of the third wiring part 231 may be 1.5 to 3 times or 2 to 2.5 times the width w2 of the fifth pad part 232.

When the width w1 of the third wiring part 231 exceeds three times the width w2 of the fifth pad part 232, the gap between the third circuit patterns narrows, and the adjacent third circuit pattern becomes narrower. The third circuit pattern may be short-circuited due to contact with the circuit pattern. Additionally, the number of third circuit patterns disposed in the chip mounting area may be reduced, thereby increasing the size of the layer structure of the chip.

Additionally, the width (w1) of the third wiring portion 231 may be greater than or equal to the distance (G) between the third wiring portion 231 and the terminal portion 400. Additionally, the width (w1) of the third wiring portion 231 may be less than or equal to the length (L) of the terminal portion 400. Additionally, the width w1 of the third wiring portion 231 may be larger or smaller than the width w3 of the terminal portion 400.

For example, the width w1 of the third wiring portion 231 may be 20 μm to 30 μm. Additionally, the width (w2) of the fifth pad portion 232 may be 9 μm to 20 μm. Additionally, the distance (G) between the third wiring portion 231 and the terminal portion 400 may be 10 μm to 30 μm. Additionally, the length (L) of the terminal portion 400 may be 30 μm to 50 μm. Additionally, the width (w3) of the terminal portion 400 may be 15 μm to 50 μm.

Meanwhile, in FIGS. 2 and 5, the third wiring portion 231 is shown to have a square shape, but the embodiment is not limited thereto.

Referring to FIG. 6, the third wiring portion 231 may be formed in various shapes. For example, referring to (a) of FIG. 6, the third wiring portion 231 may be formed in a hexagonal shape. Alternatively, referring to (b) of FIG. 6, the width of the third wiring portion 231 may decrease from the center to the outside. Alternatively, referring to (c) of FIG. 6, the third wiring unit 231 may include a curved surface. Accordingly, it is possible to prevent the width of the pattern from suddenly changing in the boundary area between the third wiring part 231 and the fifth pad part 232. As a result, it is possible to prevent stress from being concentrated in the boundary area between the fifth pad portion 232 and the third wiring portion 231, so that the fifth pad portion 232 and the third wiring portion 231 ) can prevent cracks in the border area.

Alternatively, referring to (d) of FIG. 6 , the third wiring portion 231 may protrude in one direction of the third wiring portion 231 . Accordingly, the spacing of the third circuit pattern can be easily controlled. In detail, the gap between the third circuit pattern and the adjacent third circuit pattern may be narrowed by the third wiring portion having a large width. Accordingly, by controlling the position of the third wiring unit according to the space of the chip mounting area, the spacing of the third circuit pattern can be easily controlled.

The flexible printed circuit board according to the embodiment may vary the width of the third circuit pattern for each region. In detail, the width of the fifth pad portion of the third circuit pattern may be smaller than that of the wiring portion. Accordingly, it is possible to prevent the terminal portion of the chip disposed on the fifth pad portion from interfering with another fifth pad portion. Additionally, in order to prevent interference of the terminal portion, the gap between the third circuit patterns can be prevented from increasing.

Additionally, the width of the wiring portion of the third circuit pattern may be larger than that of the fifth pad portion. Accordingly, it is possible to prevent the wiring portion of the third circuit pattern from being deformed or cracked due to stress generated when the third circuit pattern and the terminal portion are bonded.

Additionally, since the width of the wiring portion of the third circuit pattern is increased, heat generated when or after mounting the chip can be effectively dissipated. That is, the wiring portion of the third circuit pattern may serve as a heat dissipation pattern. Accordingly, the internal temperature of the flexible printed circuit board or COF module can be reduced.

Accordingly, the flexible printed circuit board according to the embodiment can be manufactured in a small size, have improved electrical characteristics, and can effectively radiate internal heat.

below. A flexible printed circuit board according to another embodiment will be described with reference to FIGS. 7 to 14 .

Referring to FIGS. 7 and 8 , the third wiring portion 231 may include areas with different widths. In detail, the third wiring part 231 may include a 3-1 wiring part 231a and a 3-2 wiring part 231b.

The 3-1 wiring portion 231a may be disposed adjacent to the fifth pad portion 232. In detail, the 3-1 wiring part 231a may be connected to the fifth pad part 232. Additionally, the 3-2 wiring portion 231b may be connected to the 3-1 wiring portion 231a. In detail, the 3-1 wiring portion 231a may be connected to the end of the 3-2 wiring portion 231b, that is, the 3-1 wiring portion 231a may be connected to the fifth pad portion 232. ) and the 3-2 wiring portion 231b.

The width (w1-1) of the 3-1 wiring portion 231a and the width (w-2) of the 3-2 wiring portion 231b are greater than the width (w2) of the fifth pad portion 232. It can be big. Accordingly, since the unit area of the third wiring portion increases, the 3-1 wiring portion 231a and the 3-2 It is possible to prevent the shape of the wiring portion 231b from being deformed or cracks from occurring.

In addition, the width (w1-1) of the 3-1 wiring part 231a and the width (w1-2) of the 3-2 wiring part 231b may be different. In detail, the 3-1 wiring part The width w1-1 of the portion 231a may be larger than the width w1-2 of the 3-2 wiring portion 231b. That is, the width of the area adjacent to the fifth pad unit 232 of the third wiring unit 231 may be larger than the width of the area further away from the fifth pad unit 232.

Stress that occurs when the fifth pad portion 232 and the terminal portion 400 are bonded may be greatest in an area adjacent to the fifth pad portion 232. Accordingly, in consideration of the distribution of stress transmitted to the third wiring portion 231, the width w1-1 of the 3-1 wiring portion 231a adjacent to the fifth pad portion 232 is changed to the third wiring portion 231. 3-2 It can be larger than the width (w1-2) of the wiring portion 231b. Accordingly, when bonding the third circuit pattern and the chip, the third circuit pattern can be prevented from being deformed or cracked.

Therefore, the flexible printed circuit board according to the embodiment may have improved electrical characteristics.

Referring to FIGS. 9 to 12 , a plurality of third circuit patterns may be disposed in the chip mounting area CA. For example, the third circuit pattern may include a 3-1 circuit pattern 230a, a 3-2 circuit pattern 230b, and a 3-3 circuit pattern 230c.

The 3-1 circuit pattern 230a and the 3-2 circuit pattern 230b may be disposed adjacent to each other. Additionally, the 3-2 circuit pattern 230b and the 3-3 circuit pattern 230c may be disposed adjacent to each other. For example, the 3-1 circuit pattern 230a is disposed in the center of the chip mounting area CA, and the 3-2 circuit pattern 230b and the 3-3 circuit pattern 230c are It may be disposed between the center and the outer portion of the chip mounting area (CA).

9 and 10, the wiring portion of any one of the 3-1 circuit pattern 230a, the 3-2 circuit pattern 230b, and the 3-3 circuit pattern 230c. The width may be different from the width of the wiring portion of another circuit pattern. In detail, the width (w4) of the wiring portion of the 3-1 circuit pattern 230a is the width (w5) of the wiring portion of the 3-2 circuit pattern 230b and the wiring portion of the 3-3 circuit pattern 230c. It may be larger than the width of the negative width (w5). Accordingly, the third circuit pattern may have a larger wiring portion of the circuit pattern disposed in the center of the chip mounting area CA among the plurality of circuit patterns.

Additionally, the 3-1 circuit pattern 230a, the 3-2 circuit pattern 230b, and the 3-3 circuit pattern 230c may be arranged at different intervals. In detail, the first gap d1 between the 3-1 circuit pattern 230a and the 3-2 circuit pattern 230b and the 3-2 circuit pattern 230b and the 3-3 circuit pattern The second interval d2 between 230c may be different. For example, the first interval d1 may be smaller than the second interval d2.

Alternatively, referring to FIGS. 11 and 12, the widths of the circuit patterns of the 3-1 circuit pattern 230a, the 3-2 circuit pattern 230b, and the 3-3 circuit pattern 230c may be different. You can. In detail, the width (w4) of the wiring portion of the 3-1 circuit pattern 230a is the width (w5) of the wiring portion of the 3-2 circuit pattern 230b and the wiring portion of the 3-3 circuit pattern 230c. It may be larger than the width of the negative width (w5). Additionally, the width w5 of the wiring portion of the 3-2 circuit pattern 230b may be greater than the width w5 of the wiring portion of the 3-3 circuit pattern 230c. Accordingly, in the plurality of third circuit patterns, the width of the wiring portion of the 3-1 circuit pattern disposed in the center of the chip mounting area is the largest, and the width of the wiring portion of the third circuit pattern becomes smaller as it moves away from the central portion. You can lose.

That is, the width of the wiring portion of the plurality of third circuit patterns may become smaller toward the outer area of the chip mounting area. Alternatively, the spacing between the wiring portions of the plurality of third circuit patterns may increase toward the outer area of the chip mounting area.

The pad portion of the first circuit pattern, the second circuit pattern, and the third circuit pattern and the terminal portion of the chip may be bonded at high temperature and high pressure. At this time, the temperature and pressure of the central portion of the chip mounting area (CA) may be higher than those of other portions. Accordingly, the third circuit pattern disposed in the central portion of the chip mounting area may generate greater stress than the third circuit pattern disposed in other locations.

Accordingly, the width of the wiring portion of the third circuit pattern disposed in the center of the chip mounting area among the plurality of third circuit patterns can be made larger than the width of the wiring portion of the other third circuit patterns. Alternatively, the width of the wiring portion of the third circuit pattern may be reduced while extending from the center of the chip mounting area toward the outer portion.

Accordingly, even if different stresses occur at each location when bonding the pad portion of the third circuit pattern and the terminal portion of the chip, deformation and cracking of the third circuit pattern can be effectively prevented.

Referring to FIGS. 13 and 14 , the third circuit pattern 230 may have the same or similar width as the third wiring portion 231 and the fifth pad portion 232 . Additionally, the third circuit pattern 230 may have a thickness (T1) of the third wiring portion and a thickness (T2) of the fifth pad portion 232 that are different from each other.

In detail, the thickness T1 of the third wiring part may be greater than the thickness T2 of the fifth pad part 232.

Since the thickness T1 of the third wiring portion is greater than the thickness T2 of the fifth pad portion 232, when the fifth pad portion 232 and the terminal portion 400 are bonded, the third wiring portion (231) can be prevented from being damaged. In detail, the strength of the third wiring portion 231 can be increased by increasing the thickness T1 of the third wiring portion greater than the thickness T2 of the fifth pad portion 232. Accordingly, it is possible to prevent the shape of the third wiring part 231 from changing or from cracking due to stress generated during the bonding process between the chip and the fifth pad part.

Additionally, unlike the previously described embodiment, the width of the third wiring portion and the width of the fifth pad portion 232 may be the same or similar. Accordingly, the spacing between the third circuit patterns can be widened. Thereby, it is possible to prevent the third circuit pattern from being short-circuited. Alternatively, the size of the chip mounting area may be reduced. Accordingly, a small-sized flexible printed circuit board can be manufactured. Alternatively, the number of third circuit patterns disposed in the chip mounting area may be increased.

Figure 15 is a top view of a COF module according to an embodiment.

Referring to FIG. 15, the COF module according to the embodiment includes the flexible printed circuit board described above, and may include a chip (CH) disposed in the chip mounting area (CA) of the flexible printed circuit board 1000. .

Additionally, the flexible printed circuit board 1000 may include the protective layer 300 described above.

Meanwhile, the COF module can be manufactured by cutting the flexible printed circuit board 1000 and then mounting the chip (CH). In detail, the flexible printed circuit board 1000 is cut along the cutting line CL in FIG. 1. Subsequently, a driving chip electrically connected to the first, second, and third circuit patterns may be mounted on the chip mounting area of the flexible printed circuit board.

For example, after testing the driving characteristics of the flexible printed circuit board through wiring and pad portions disposed outside the cutting line (CL) of the flexible printed circuit board, the flexible printed circuit board is cut along the cutting line (CL). can do.

The COF module is located between the display panel and the substrate and can connect electrical signals.

That is, the pad portions of the first and second circuit patterns that are exposed without the protective layer 300 may be connected to the display panel, the printed circuit board, and the chip in the chip mounting area.

Referring to FIG. 16, one end of the COF module 2000 including a flexible printed circuit board according to the embodiment is connected to the display panel 3000, and the other end opposite to the one end is connected to the printed circuit board 4000. can be connected

For example, one end of the COF module 2000 including a flexible printed circuit board according to the embodiment is electrically connected by contacting the display panel 3000, and the other end opposite to the one end is connected to the printed circuit board ( 4000) can be electrically connected. Here, contact may mean direct contact. Alternatively, it may mean contact with an anisotropic conductive film (ACF) in between.

Since the COF module 2000 includes a flexible substrate, it may have a rigid or bent shape between the display panel 3000 and the printed circuit board 4000.

The COF module 2000 can connect the display panel 3000 and the printed circuit board 4000, which are disposed opposite each other, in a curved form, thereby reducing the thickness of the electronic device and improving design freedom. You can do it. In addition, the COF module 2000 including the flexible substrate may not have broken wires even in a bent shape, thereby improving the reliability of an electronic device including the COF module.

Because the COF module is flexible, it can be used in various electronic devices.

For example, referring to FIG. 17, the COF module may be included in a bendable flexible touch window. Accordingly, a touch device including this may be a flexible touch device. Therefore, the user can bend or bend it by hand. These flexible touch windows can be applied to wearable touches, etc.

Referring to FIG. 18, the COF module may be included in various wearable touch devices including curved displays. Accordingly, the electronic device including the COF module can be slimmed or lightened.

Referring to FIG. 19, the COF module can be used in various electronic devices having a display portion, such as TVs, monitors, and laptops. At this time, the COF module can also be used in an electronic device having a curved display portion.

However, the embodiment is not limited to this, and of course, the COF flexible printed circuit board and the COF module processed therefrom can be used in various electronic devices.

The features, structures, effects, etc. described in the above-described embodiments are included in at least one embodiment of the present invention and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified and implemented in other embodiments by a person with ordinary knowledge in the field to which the embodiments belong. Therefore, contents related to such combinations and modifications should be construed as being included in the scope of the present invention.

In addition, although the description has been made focusing on the embodiments above, this is only an example and does not limit the present invention, and those skilled in the art will understand the above examples without departing from the essential characteristics of the present embodiments. You will be able to see that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. And these variations and differences in application should be construed as being included in the scope of the present invention as defined in the attached claims.

Claims (10)

A substrate including a chip mounting area; and
Includes a circuit pattern disposed on the substrate,
The circuit pattern includes a first circuit pattern, a second circuit pattern, and a third circuit pattern,
The first circuit pattern includes a first pad portion disposed inside the chip mounting area, a second pad portion disposed outside the chip mounting area, and a first pad portion connected to the first pad portion and the second pad portion. Includes a wiring section,
The second circuit pattern includes a third pad portion disposed inside the chip mounting area, a fourth pad portion disposed outside the chip mounting region, and a second pad portion connected to the third pad portion and the fourth pad portion. Includes a wiring section,
The third circuit pattern includes a third wiring portion and a fifth pad portion disposed inside the chip mounting area,
A flexible printed circuit board wherein the third wiring portion has a width greater than the fifth pad portion. According to clause 1,
A flexible printed circuit board wherein the width of the third wiring portion is greater than 1 to 3 times the width of the fifth pad portion. According to clause 1,
The third wiring portion includes a 3-1 wiring portion connected to the fifth pad portion and a 3-2 wiring portion connected to the 3-1 wiring portion,
A flexible printed circuit board wherein the width of the 3-1 wiring part and the width of the 3-2 wiring part are different. According to clause 3,
A flexible printed circuit board wherein the width of the 3-1 wiring portion is greater than the width of the 3-2 wiring portion. According to clause 1,
The third circuit pattern is disposed in the chip mounting area and includes a 3-1 circuit pattern, a 3-2 circuit pattern, and a 3-3 circuit pattern adjacent to each other,
The 3-1 circuit pattern is disposed in the center of the chip mounting area,
The 3-2 circuit pattern and the 3-3 circuit pattern are disposed between a central portion and an outer portion of the chip mounting area,
A flexible printed circuit board wherein the width of any one of the 3-1 circuit pattern, the 3-2 circuit pattern, and the 3-3 circuit pattern is different from the width of the other circuit pattern. According to clause 5,
A flexible printed circuit board wherein the width of the wiring portion of the 3-1 circuit pattern is greater than the width of the wiring portion of the 3-2 circuit pattern and the 3-3 circuit pattern. According to clause 1,
The third circuit pattern is disposed in the chip mounting area and includes a 3-1 circuit pattern, a 3-2 circuit pattern, and a 3-3 circuit pattern adjacent to each other,
A flexible printed circuit board wherein the width of the wiring portion of the third circuit pattern becomes smaller as it extends from the center to the outer portion of the chip mounting area. A flexible printed circuit board according to any one of claims 1 to 7; and
Including a chip disposed in the chip mounting area,
The chip is a COF module connected to the first pad unit, the third pad unit, and the fifth pad unit. According to clause 8,
The width of the third wiring portion is greater than or equal to the distance between the third wiring portion and the terminal portion of the chip,
A COF module in which the width of the third wiring portion is less than or equal to the length of the terminal portion. COF module according to claim 8;
a printed circuit board connected to the first circuit pattern; and
An electronic device including a display panel connected to the second circuit pattern.

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