Printed circuit board and method for manufacturing the same

Abstract

To provide a printed circuit board and a method for manufacturing the same.SOLUTION: The present invention relates to a printed circuit board and a method for manufacturing the same, includes a first insulating layer, a pad arranged on the first insulating layer, a protrusion arranged on the pad, and a metal post arranged on the pad and covering the protrusion, the metal post having a tapered shape such that a width of an upper surface is narrower than a width of a lower surface.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a printed circuit board and a method for manufacturing a printed circuit board. [Background technology]

[0002] Recently, with the development of artificial intelligence (AI) technology, etc., multi-chip packages including memory chips such as HBM (High Bandwidth Memory) for processing data that has increased exponentially, and processor chips such as CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), and FPGA (Field Programmable Gate Array) are being used. In particular, the number of cores of CPU and GPU in server products is rapidly increasing, and it is necessary to deal with finer pitch of chip metal posts. In particular, alignment of connecting members becomes an issue when connecting chips and substrates, and defects may occur due to separation of pads or connecting members caused by pressure generation, and defects such as short circuits occurring between connecting members may occur. Therefore, research is being conducted to realize substrate and package structures that can reduce the pitch of metal posts in response to the demand for high density, and to increase yield while improving connection reliability. Summary of the Invention [Problem to be solved by the invention]

[0003] One of the various objects of the present invention is to provide a printed circuit board and a method for manufacturing the printed circuit board, which can realize metal posts having fine pitch in a printed circuit board for mounting electronic components, semiconductor chips, etc.

[0004] Another of the various objects of the present invention is to provide a printed circuit board and a method for manufacturing the printed circuit board that can realize protruding metal posts.

[0005] Another of the various objects of the present invention is to provide a printed circuit board and a method for manufacturing the printed circuit board that can improve reliability. [Means for solving the problem]

[0006] One of several solutions proposed through the present invention is to provide a printed circuit board including a first insulating layer, a pad disposed on the first insulating layer, a protrusion disposed on the pad, and a metal post disposed on the pad and covering the protrusion, the metal post having a tapered shape such that the width of an upper surface is narrower than the width of a lower surface.

[0007] Another of several solutions proposed through the present invention is to provide a method for manufacturing a printed circuit board, comprising the steps of forming a pad on a first insulating layer, forming a protrusion on the pad, and forming a metal post on the pad to cover the protrusion, the metal post having a tapered shape such that the width of an upper surface is narrower than the width of a lower surface. Effect of the Invention

[0008] Among the various effects of the present invention, one effect is that it is possible to provide a printed circuit board and a method for manufacturing a printed circuit board that can realize metal posts having fine pitch in a printed circuit board for mounting electronic components, semiconductor chips, etc.

[0009] Another advantage of the present invention is that it provides a printed circuit board and a method for manufacturing the printed circuit board that can realize protruding metal posts without etching an insulating layer.

[0010] Another advantage of the present invention is that it provides a printed circuit board and a method for manufacturing the printed circuit board that can improve reliability. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram illustrating a schematic example of an electronic device system. [Diagram 2] FIG. 1 is a perspective view illustrating an example of an electronic device. [Diagram 3] FIG. 1 is a plan view illustrating a schematic diagram of a printed circuit board according to an example. [Figure 4] FIG. 1 is a cross-sectional view illustrating a schematic configuration of a printed circuit board according to an example. [Diagram 5] FIG. 11 is a cross-sectional view illustrating a printed circuit board according to another example. [Figure 6] 1A to 1C are cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 7] 1A to 1C are cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 8] 1A to 1C are cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 9] 1A to 1C are cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 10] 1A to 1C are cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 11] 1A to 1C are cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 12] 1A to 1C are cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 13] 1A to 1C are cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will now be described with reference to the accompanying drawings, in which the shapes and sizes of elements may be exaggerated or reduced for clarity.

[0013] electronic equipment FIG. 1 is a block diagram illustrating an example of an electronic device system.

[0014] Referring to the drawing, an electronic device 1000 accommodates a main board 1010. Chip-related components 1020, network-related components 1030, and other components 1040 are physically and / or electrically connected to the main board 1010. These are also connected to other electronic components described below to form various signal lines 1090.

[0015] The chip-related components 1020 include, but are not limited to, memory chips such as volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), and flash memory; application processor chips such as central processors (e.g., CPU), graphic processors (e.g., GPU), digital signal processors, encryption processors, microprocessors, and microcontrollers; and logic chips such as analog-to-digital converters and ASICs (application-specific ICs). Needless to say, the chip-related components 1020 may include other types of chip-related electronic components. Needless to say, these chip-related components 1020 may be combined with each other. The chip-related components 1020 may be in the form of a package including the above-mentioned chips and electronic components.

[0016] The network-related components 1030 may include, but are not limited to, any other wireless and wired protocols designated as Wi-Fi (e.g., IEEE 802.11 family), WiMAX (e.g., IEEE 802.16 family), IEEE 802.20, LTE (long term evolution), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPS, GPRS, CDMA, TDMA, DECT, Bluetooth, 3G, 4G, 5G, and beyond, as well as any of a number of other different wireless or wired standards and protocols. It should be understood that the network-related components 1030 may also be combined with the chip-related components 1020 and with each other.

[0017] The other components 1040 include high-frequency inductors, ferrite inductors, power inductors, ferrite beads, LTCC (low temperature co-firing ceramics), EMI (electromagnetic interference) filters, MLCC (multi-layer ceramic capacitors), etc. However, the other components 1040 are not limited to these, and may also include passive elements in the form of chip components used for various other different applications. It goes without saying that the other components 1040 may be combined with the chip-related components 1020 and / or the network-related components 1030.

[0018] Depending on the type of electronic device 1000, the electronic device 1000 may include other electronic components that may or may not be physically and / or electrically coupled to the main board 1010. Examples of other electronic components include, but are not limited to, a camera module 1050, an antenna module 1060, a display 1070, and a battery 1080. The other electronic components may include, but are not limited to, an audio codec, a video codec, a power amplifier, a compass, an accelerometer, a gyroscope, a speaker, a mass storage device (e.g., a hard disk drive), a compact disk (CD), a digital versatile disk (DVD), and the like. Needless to say, other electronic components used for various purposes may be included depending on the type of electronic device 1000.

[0019] The electronic device 1000 may be a smart phone, a personal digital assistant, a digital video camera, a digital still camera, a network system, a computer, a monitor, a tablet, a laptop, a netbook, a television, a video game, a smart watch, an automotive, etc. However, the electronic device 1000 is not limited to these, and may be any other electronic device that processes data.

[0020] FIG. 2 is a perspective view that illustrates an example of an electronic device.

[0021] Referring to the drawings, the electronic device may be, for example, a smartphone 1100. A motherboard 1110 is housed inside the smartphone 1100, and various components 1120 are physically and / or electrically connected to the motherboard 1110. In addition, other components such as a camera module 1130 and / or a speaker 1140 that may or may not be physically and / or electrically connected to the motherboard 1110 are housed inside the smartphone 1100. Some of the components 1120 may be the above-mentioned chip-related components, for example, a component package 1121, but are not limited thereto. The component package 1121 may be in the form of a printed circuit board on which electronic components including active components and / or passive components are surface-mounted. Alternatively, the component package 1121 may be in the form of a printed circuit board in which active components and / or passive components are built-in. Meanwhile, it goes without saying that the electronic device is not necessarily limited to the smartphone 1100, and may be other electronic devices as described above.

[0022] Printed Circuit Board Fig. 3 is a plan view showing an example of a printed circuit board, and Fig. 4 is a cross-sectional view showing an example of a printed circuit board, in which Fig. 3 is a top view of the printed circuit board, and Fig. 4 is a cross-sectional view of the printed circuit board in Fig. 3 taken along the II' direction.

[0023] Referring to FIG. 3, the printed circuit board according to an example has an area for mounting a semiconductor chip or the like. The printed circuit board according to an example has an upper surface covered with a solder resist layer 160, and the pads 120 and the metal posts 140 may be exposed through openings in the solder resist layer. A surface treatment layer 150 may be included on the exposed surfaces of the pads 120 and the metal posts 140. A connecting member 170 may be disposed on the metal posts 140. The printed circuit board according to an example may have the metal posts 140 protruding from an insulating layer, which may be advantageous when mounting a fine-pitch semiconductor chip or the like due to the protruding metal posts 140. The printed circuit board according to an example will be described in more detail with reference to the cross-sectional view of FIG. 4.

[0024] Referring to FIG. 4, an example printed circuit board may include a first insulating layer 110, a pad 120 disposed on the upper side of the first insulating layer 110, a protrusion 130 disposed on the pad 120, and a metal post 140 disposed on the pad 120 and covering the protrusion 130.

[0025] The first insulating layer 110 may include an insulating material. The insulating material may include a thermosetting resin such as an epoxy resin, a thermoplastic resin such as a polyimide, or a material including an inorganic filler, an organic filler, and / or a glass fiber (glass fiber, glass cloth, and / or glass fabric) together with such a resin. The insulating material may be a photosensitive material and / or a non-photosensitive material. For example, the insulating material of the first insulating layer 110 may be an insulating material of ABF (Ajinomoto Build-up Film), but is not limited thereto, and may include PPG (Prepreg), RCC (Resin Coated Copper), PID (Photo) Imageable Dielectric), FR-4, BT (Bismaleimide Triazine), etc. However, it is not limited thereto, and other materials having excellent rigidity may be used as necessary.

[0026] The pads 120 may include a metal material. Examples of the metal material include copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), lead (Pb), titanium (Ti), and alloys thereof. The metal material may preferably include, but is not limited to, copper (Cu). The pads 120 may be regions for mounting electronic components and chips, and may be connected to a circuit pattern for signal connection with other pads. The pads 120 may perform various functions according to the design. For example, they may include ground pads, power pads, and signal pads. Here, the signal pads may include pads for electrical connection of various signals, such as data signals, other than ground and power. When a high density fine pitch is required for mounting a semiconductor chip, the pads 120 may have a narrower interval between them, and when mounting an electronic component, the pads 120 may have a wider interval between them.

[0027] The pad 120 may be formed of a plurality of pads. The plurality of pads 120 may be formed simultaneously in the formation step of the pad 120, but is not limited thereto, and may be formed sequentially or in stages as necessary. In addition, the pads 120 may electrically transmit and receive signals to and from different pads 120 and / or circuits, and may perform functions by being electrically shorted to other pads 120.

[0028] The pad 120 may be formed by any one of a semi-additive process (SAP), a modified semi-additive process (MSAP), a tenting process (TT), or a subtractive process, but is not limited thereto. The pad 120 may be composed of a first metal layer 121 disposed on the first insulating layer 110 and a second metal layer 122 disposed on the first metal layer 121.

[0029] The first metal layer 121 and the second metal layer 122 may include a metal material and may be selected from the group of metal materials of the pad 120 described above. The first metal layer 121 and the second metal layer 122 may include the same metal, and preferably, the first metal layer 121 and the second metal layer 122 may each include copper (Cu), but are not limited thereto, and the first metal layer 121 and the second metal layer 122 may include different metals as necessary.

[0030] The first metal layer 121 is disposed on the first insulating layer 110 and can function as a seed for forming the second metal layer 122, the protrusion 130, and the metal post 140. The first metal layer 121 can include, but is not limited to, an electroless plating layer (or chemical copper) formed by electroless plating, and can include a sputtering layer formed by sputtering instead of electroless plating, or can include both an electroless plating layer and a sputtering layer. It is not limited to this, and can include copper foil as necessary, and any metal that can function as a seed for electrolytic plating can be used without restriction.

[0031] The second metal layer 122 is disposed on the first metal layer 121 and may be formed using the first metal layer 121 as a seed. The second metal layer 122 may include an electrolytic plating layer (or electrolytic copper) formed by electrolytic plating. However, without being limited thereto, the second metal layer 122 may be formed by firing a paste containing a metal material. Meanwhile, the method of forming the second metal layer 122 is not limited thereto and may further include a configuration or method available to a person having ordinary skill in the art.

[0032] Meanwhile, in FIG. 4, the pad 120 is shown as being disposed on the first insulating layer 110, but is not necessarily limited thereto. The pad 120 may be disposed on the upper side of the first insulating layer 110, as shown in FIG. 4, of course includes the pad 120 being disposed on the upper surface of the first insulating layer 110, and also includes the pad 120 being disposed on the upper surface side of the first insulating layer 110 and having a structure embedded in the first insulating layer 110. That is, the pad 120 may have a structure embedded on the upper side of the first insulating layer 110, and in this case, the printed circuit board according to the example may have a so-called coreless substrate structure. When the pad 120 is embedded on the upper side of the first insulating layer 110, the first metal layer 121 of the pad 120 may be disposed so that the first insulating layer 110 faces upward, and the arrangement of the first metal layer and the second metal layer 122 may be different, and in some cases, the pad 120 may not include the first metal layer 121. That is, in the case of a coreless substrate structure, the arrangement of the seed may be different from that of FIG. 4, and in some cases, the seed may be removed. In the case of a coreless substrate structure, after detaching the carrier substrate, the protrusion 130 may be arranged on the pad 120 embedded on the upper side of the first insulating layer 110. In the case of a coreless substrate structure, the present invention is not limited to the above, and may include a substrate configuration that is available to a person having ordinary skill in the art.

[0033] The protrusion 130 may be disposed on the second metal layer 122 of the pad 120. The width of the protrusion 130 may be narrower than the width of the pad 120, and the protrusion 130 may be disposed to be located at the center of the pad 120, but is not limited thereto. The protrusion 130 may include a metal material, and examples of the metal material include copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), lead (Pb), titanium (Ti), and alloys thereof. The metal material may preferably include copper (Cu), and may include a metal material similar to the second metal layer 122 of the pad 120, but is not necessarily limited thereto. The protrusion 130 may be formed by electrolytic plating using the first metal layer 121 of the pad 120 as a seed, but is not necessarily limited thereto, and may further include a configuration or method available to a person having ordinary skill in the art. Meanwhile, without being limited thereto, the protrusion 130 may include an insulating material. The insulating material may be a photosensitive insulating material or a non-photosensitive insulating material. The protrusion 130 may be formed by patterning a photosensitive insulating material, or may be formed by disposing an insulating material on the pad 120 and curing it. Alternatively, the protrusion 130 may include an oxide. The protrusion 130 does not necessarily have to correspond to any one of the above-mentioned materials, but may have a structure disposed on the pad 120 and protruding onto a part of the pad 120.

[0034] The protrusion 130 is disposed on the pad 120 and can be formed in a separate step from the pad 120, so that the protrusion 130 can be distinguished from the pad 120. That is, even if the protrusion 130 and the second metal layer 122 of the pad 120 contain the same metal material, the boundary between them can be distinguished and confirmed by observing a cut cross section of the printed circuit board with a scanning microscope. Alternatively, the boundary between the second metal layer 122 of the pad 120 and the protrusion 130 can be confirmed by performing a certain process on the cut cross section of the printed circuit board and observing the grain boundaries of the metal material.

[0035] The protrusion 130 is disposed on the pad 120, and can control the shape of the metal post 140. In the step of forming an opening in the dry film for forming the metal post 140, the protrusion 130 is disposed on a part of the pad 120, so that an upward tapered shape can be obtained in the step of exposing and developing the dry film. That is, in the step of exposing and developing the dry film, the protrusion 130 can form an opening having a tapered shape such that the width on the upper side is narrower than the width on the lower side.

[0036] The thickness of the protrusion 130 may be smaller than the thickness of the pad 120. The protrusion 130 is disposed on the pad 120 and serves as an intermediate for forming the metal post 140, and may be smaller in thickness than the pad 120. The thickness of the protrusion 130 and the thickness of the pad 120 may be measured by photographing a cross section of the printed circuit board in the lamination direction with a scanning microscope or the like. The thickness of a certain component may be interpreted as a distance across a certain component, but may include measurement errors or errors in the manufacturing process. For example, the thickness of the pad 120 may be an average value of the vertical distances between the bottom surface and the top surface of the pad 120 measured at any five points on one pad 120. The thickness of the protrusion 130 may also be measured and compared in a similar manner.

[0037] The metal post 140 may be disposed on the pad 120 so as to cover the protrusion 130. The metal post 140 may have a tapered shape such that the width of the upper surface is narrower than the width of the lower surface.

[0038] The metal post 140 may include a metal material. The metal material may be copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), lead (Pb), titanium (Ti), or an alloy thereof. The metal material may preferably include copper (Cu), but is not limited thereto. The metal post 140 may be a region for mounting electronic components and chips, or may be configured to protrude in order to facilitate connection when electronic components and chips are mounted on the pad 120. The metal post 140 may perform various functions according to the design of the pad 120. When a high-density fine pitch is required in the pad 120 for mounting a semiconductor chip, not only the interval between the pads 120 but also the interval between the metal posts 140 may be narrow. The metal post 140 may be formed of a plurality of metal posts 140. The plurality of metal posts 140 may be formed simultaneously in the formation of the metal posts 140, but is not limited thereto, and may be formed sequentially or in stages as necessary. Additionally, the metal post 140 can electrically transmit and receive signals to and from the pad 120 .

[0039] The metal post 140 may be formed by any one of a semi-additive process (SAP), a modified semi-additive process (MSAP), a tenting (TT), or a subtractive method, but is not limited thereto. The metal post 140 may be formed by performing electrolytic plating using the first metal layer 121 of the pad 120 as a seed, but is not necessarily limited thereto, and may be formed by a method available to a person having ordinary skill in the art.

[0040] Since the metal post 140 can be formed to fill the opening of the dry film, the shape of the metal post 140 can be determined by the shape of the opening of the dry film. As described above, by disposing the protrusion 130 on the pad 120, the opening of the dry film can have a tapered shape such that the width of the upper surface is narrower than the width of the lower surface, and thus the metal post 140 can have a tapered shape such that the width of the upper surface is narrower than the width of the lower surface. The width of the metal post 140 can be measured by photographing a cross section of the printed circuit board in the lamination direction using a scanning microscope or the like. The width of a certain feature can be interpreted as a distance across a certain feature, but may include measurement errors or errors in the manufacturing process. Meanwhile, in FIG. 4, the shape of the metal post 140 is shown to change linearly with a certain rate of change, but this is merely an example, and the side of the metal post 140 may have a curved line, such as a curved inclined surface on the side of the metal post 140.

[0041] The width of the metal post 140 may be narrower than the width of the pad 120. The width of the pad 120 may also be measured by photographing a cross section of the printed circuit board in the lamination direction using a scanning microscope or the like. For example, the width of the pad 120 may be an average value of horizontal distances between the sides of the pad 120 measured at any five points on one pad 120. If the pad 120 has a circular shape, the width of the pad 120 may mean the diameter of the pad 120, if the pad 120 has a polygonal shape, the width of the pad 120 may be measured as the diagonal line of the polygon or the distance between two opposing sides, and if the pad 120 has an elliptical shape, the width of the pad 120 may be defined as the minor axis of the ellipse. Meanwhile, as described above, since the width of the metal post 140 is different between the upper surface and the lower surface, the width of the metal post 140 to be compared with the width of the pad 120 may be measured at the surface where the pad 120 and the metal post 140 contact each other. In this case, the width of the metal post 140 may be measured including the protrusion 130 located at the center of the metal post 140. That is, the width of the metal post 140 may refer to the distance of the outer surface of the metal post 140 including the protrusion 130 .

[0042] By disposing the metal post 140 on the pad 120, even if a fine-pitch semiconductor chip is mounted, the possibility of a short circuit occurring in the connecting member 170 disposed between the semiconductor chip and the metal post 140 can be reduced, and the failure of the semiconductor chip being detached can also be reduced. In addition, by disposing the metal post 140 on the pad 120, it is possible to ensure a stronger adhesion than a structure in which the connecting member 170 is disposed directly on the pad 120, thereby improving the reliability of the printed circuit board.

[0043] The printed circuit board according to an example may further include a solder resist layer 160 on the first insulating layer 110. The solder resist layer 160 is disposed on the first insulating layer 110 and is disposed on the outermost side of the printed circuit board to protect the printed circuit board from the outside. The solder resist layer 160 may use a known solder resist, and the solder resist layer 160 may include a thermosetting resin and an inorganic filler dispersed in the thermosetting resin, but may not include glass fiber. The insulating resin may be a photosensitive insulating resin, and the filler may be an inorganic filler and / or an organic filler, but is not limited thereto, and other polymer materials may be used as necessary. When a photosensitive insulating resin is used as the solder resist layer 160, it is advantageous to form fine openings, and in this case, it may be more advantageous for a printed circuit board having a fine pitch. In addition, the solder resist layer 160 may include a liquid material. The solder resist layer 160 may include a liquid material, and the step of forming the solder resist layer 160 may include applying a liquid material, followed by exposure, development, and curing. Since the printed circuit board according to an example includes the protruding metal post 140, when the solder resist layer 160 includes a liquid material, the solder resist layer 160 may be conformally disposed along the boundary of the shape of the protruding metal post 140. When the solder resist layer 160 is in a film form, a thermal compression process may be performed, and there is a risk that the protruding metal post 140 may be partially deformed during the thermal compression process. However, the solder resist layer 160 is not necessarily limited to this, and a film-like material may be used as long as it does not cause defects in the protruding metal post 140 when the solder resist layer 160 is formed by controlling the thickness, hardness, and other properties.

[0044] The solder resist layer 160 may have an opening 160O, and the metal post 140 may protrude through the opening 160O. The metal post 140 protruding through the opening 160O of the solder resist layer 160 may mean that the upper surface of the metal post 140 may be located higher than the upper surface of the solder resist layer 160. It may also mean that at least a part of the side surface of the metal post 140 is not covered by the solder resist layer 160, but is not limited thereto.

[0045] The opening 160O of the solder resist layer 160 can expose at least a part of the pad 120. The fact that at least a part of the pad 120 is exposed through the opening 160O of the solder resist layer 160 can mean that the solder resist layer 160 does not cover the entire pad 120, and that at least a part of the pad 120 is not covered by the solder resist layer 160. The opening 160O of the solder resist layer 160 can expose at least a part of the upper surface of the pad. At this time, since other configurations can be further disposed on the pad 120, the fact that the opening 1600 of the solder resist layer 160 exposes at least a part of the pad 120 does not necessarily mean that at least a part of the pad 120 should be exposed to the outside of the printed circuit board, and the exposure means the relationship between the solder resist layer 160 and the pad 120. Meanwhile, the solder resist layer 160 can cover at least a part of the upper surface of the pad 120. The width of the opening 1600 in the solder resist layer 160 can be formed narrower than the width of the pad 120 , in which case the solder resist layer 160 can cover at least a portion of the top surface of the pad 120 .

[0046] 4, the opening 160O of the solder resist layer 160 is shown as exposing at least a part of the upper surface of the pad 120 and the side surface of the metal post 140, but is not limited thereto, and the opening 160O of the solder resist layer 160 can cover the entire upper surface of the pad 120 and at least a part of the side surface of the metal post 140. As a non-limiting example, the opening 160O of the solder resist layer 160 can also expose the side surface of the pad 120. The metal post 140 and / or the pad 120 exposed through the opening 160O can be connected to another component, such as a semiconductor chip, via a connecting member 170.

[0047] The printed circuit board according to an example may further include a surface treatment layer 150 disposed on the metal post 140 and / or the pad 120. The surface treatment layer 150 may include any one of nickel (Ni), palladium (Pd), and gold (Au), and may be realized by a plurality of these metal layers. For example, the surface treatment layer 150 may be at least a part of an ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) structure, or at least a part of an ENIG (Electroless Nickel Immersion Gold) structure. The surface treatment layer 150 is not limited thereto, and may include an OSP (Organic Solder Passivation) structure including an organic substance. The surface treatment layer 150 may improve the adhesion and signal transmission between the metal post 140 and the pad 120 and the connection member 170. Although the surface treatment layer 150 is illustrated as being composed of one layer in FIG. 4, the surface treatment layer 150 is not limited thereto, and may be realized by a plurality of metal layers as described above.

[0048] The surface treatment layer 150 can cover at least a portion of the metal post 140 and can also cover at least a portion of the pad 120. The surface treatment layer 150 can cover a portion of the metal post 140 and the pad 120 exposed by the opening 160O of the solder resist layer 160. At this time, since the surface treatment layer 150 can be formed after forming the solder resist layer 160 and the opening 160O, the surface treatment layer 150 can be integrally formed along the boundary between the metal post 140 and the pad 120 exposed by the opening 160O.

[0049] The printed circuit board according to an example may further include a connecting member 170 disposed on the metal post 140. The connecting member 170 may include a conductive material, for example, a solder made of tin (Sn)-silver (Ag) or copper, but the material of the connecting member 170 is not limited thereto and may further include a material available to a person having ordinary skill in the art. The connecting member 170 may be disposed on the metal post 140 in the form of a ball, but is not limited thereto.

[0050] In the printed circuit board according to an example, the connecting member 170 may be disposed before other components such as a semiconductor chip are mounted on the printed circuit board. That is, the connecting member 170 may be maintained in a state disposed on the metal post 140 before other components such as a semiconductor chip are mounted, and the printed circuit board may be a printed circuit board on which so-called micro-balls are disposed. In the printed circuit board according to an example, the metal post 140 has an upward tapered shape, so that a finer connecting member 170 can be realized, and thus a semiconductor chip having a fine pitch can be mounted. Since the connecting member 170 can be disposed on the metal post 140 of the printed circuit board all at once, it may be advantageous to align the semiconductor chip and the connecting member 170, unlike forming the connecting member 170 at the mounting stage of the semiconductor chip.

[0051] The printed circuit board according to the embodiment is not limited to the configuration shown in Fig. 4, which shows only a portion of the printed circuit board, and may further include other configurations. For example, it goes without saying that other configurations, such as an insulating layer, a circuit, and an interlayer via, may be further included below the first insulating layer 110. In other words, it may further include configurations that are available to a person of ordinary skill in the art.

[0052] FIG. 5 is a cross-sectional view that illustrates a schematic configuration of a printed circuit board according to another embodiment.

[0053] Referring to FIG. 5, the printed circuit board according to another example may further include a semiconductor chip 200 disposed on the connecting member 170.

[0054] The semiconductor chip 200 may be an integrated circuit (IC) in which hundreds to millions of circuits are integrated into one chip. Each of these may be a processor chip such as a central processor (e.g., CPU), a graphics processor (e.g., GPU), a field programmable gate array (FPGA), a digital signal processor, an encryption processor, a microprocessor, or a microcontroller, specifically, an application processor (AP: Application Processor), but is not limited thereto, and may be a logic chip such as an analog-to-digital converter or an application-specific IC (ASIC) memory controller (MC: Memory Controller) chip, or a memory chip such as a dynamic random access memory (DRAM) chip, a static random access memory (SRAM) chip, a flash memory chip, a phase-change random access memory (PRAM) chip, a magnetic random access memory (MRAM) chip, a resistive random access memory (RRAM) chip, an electrically erasable and programmable read-only memory (EEPROM) chip, or a high bandwidth memory (HBM), and it goes without saying that these may be arranged in combination with each other.

[0055] The semiconductor chip 200 may be composed of a body 201 and connection pads 202, and the surface on which the connection pads 202 for connecting to the metal posts 140 are arranged may be an active surface, and the opposite surface may be an inactive surface, but is not limited thereto, and may be capable of double-sided connection, and may have a three-dimensional structure in some cases. The semiconductor chip 200 may be formed based on an active wafer, and in this case, silicon (Si), germanium (Ge), gallium arsenide (GaAs), etc. may be used as the base material for the body 201. Various circuits may be formed in the body 201 of the semiconductor chip 200, and at least some of these circuits may be connected to the connection pads 202. In FIG. 5, the connection pads 202 are shown as being embedded in the body 201 of the semiconductor chip 200, however, this is merely an example, and the specific structure of the semiconductor chip 200 is not limited to that shown in the figure, and the connection pads 202 may have a structure in which they protrude from the body 201 of the semiconductor chip 200, or may have a structure in which the connection pads 202 are embedded by surface treatment or molding.

[0056] The connection pads 202 of the semiconductor chip 200 can be connected to the metal posts 140 via the connecting members 170, and connected to the pads 120 via the metal posts 140, so that the semiconductor chip 200 can be electrically connected to other components of the printed circuit board.

[0057] At this time, the connecting member 170 connecting the semiconductor chip 200 and the metal post 140 may have a width wider on the connection pad 202 side of the semiconductor chip 200 than on the metal post 140 side. This is a phenomenon caused by the surface tension of the connecting member 170, and may occur when the width of the upper surface of the metal post 140 is smaller than the width of the connection pad 202 of the semiconductor chip 200. That is, since the metal post 140 has a protruding structure having a tapered shape especially upward, it can correspond to the fine pitch of the semiconductor chip 200, and as a result, the width of the connecting member 170 on the side connected to the semiconductor chip 200 may be wider than the width of the metal post 140 side. At this time, since the method may include a step of heating at least a part of the connecting member 170 to connect the semiconductor chip 200 to the connecting member 170, a part of the connecting member 170 having a low melting point may be disposed to cover a part of the side of the metal post 140. On the other hand, this is not necessarily limited to this, and the width may be formed wider on the metal post 140 side, in which case the connecting member 170 may have a so-called hourglass shape in which the widths on the upper and lower sides are wider than the width at the center.

[0058] Other than the contents relating to the arrangement of the semiconductor chip 200 and the shape of the connecting member 170, the configuration similar to that of the printed circuit board of one example can also be applied to the printed circuit board of the other example, and therefore a duplicated explanation thereof will be omitted.

[0059] Printed circuit board manufacturing method 6 to 13 are cross-sectional views that are schematic diagrams illustrating a method for manufacturing a printed circuit board according to an example.

[0060] The method for manufacturing a printed circuit board according to an example may include forming a pad 120 on a first insulating layer 110, forming a protrusion 130 on the pad 120, and forming a metal post 140 on the pad 120 to cover the protrusion 130. At this time, the metal post 140 may have a tapered shape such that the width of the upper surface is narrower than the width of the lower surface. The forming of the metal post 140 may include forming a dry film 303 on the first insulating layer 110, exposing and developing at least a portion of the dry film 303 to expose at least a portion of the pad 120 and at least a portion of the protrusion 130, and forming the metal post 140 on the pad 120. At this time, the developing of at least a portion of the dry film 303 may include injecting a developer including a liquid material to form an opening having a tapered shape such that the width of the upper surface is narrower than the width of the lower surface.

[0061] 6, a method for manufacturing a printed circuit board according to an example may include forming a first metal layer 121 on a first insulating layer 110. The first metal layer 121 may be formed by electroless plating, or may be formed by sputtering, etc. As a non-limiting example, the first insulating layer 110 to which the first metal layer 121 is attached in the form of copper foil may be used.

[0062] Thereafter, the first dry film 301 may be formed. The first dry film 301 may include a photosensitive insulating material, and for example, the first dry film 301 may use a dry film resist (DFR) as a normal photosensitive resist film, but is not particularly limited thereto. The first dry film 301 may be formed on the upper surface of the insulating layer by laminating, but is not particularly limited thereto. The first dry film 301 may be formed by coating a photosensitive insulating material on the upper surface of the first insulating layer 110 and curing it, but is not particularly limited thereto, and there is no limitation as long as the first dry film 301 can be formed on at least a part of the upper surface of the first insulating layer 110. The first dry film 301 may function as a plating mask during electrolytic plating. The first dry film 301 may be a positive type or a negative type. In the case of a positive-type photosensitive insulating material, the photopolymer bond in the exposed area may break, and the broken photopolymer bond is removed in the subsequent development process. In the case of a negative-type photosensitive insulating material, the exposed area undergoes a photopolymerization reaction, changing from a single structure to a three-dimensional network structure with a chain structure, and the area not exposed to light is removed in the subsequent development process.

[0063] Thereafter, the first dry film 301 is exposed to light to deform at least a portion of the first dry film 301. In this case, the area to be exposed may vary depending on the type of the first dry film 301. In FIG. 6, the exposed portion of the first dry film 301 is shown to be deformed, but this is merely an example. Alternatively, a mask or the like may be used to deform only a portion of the first dry film 301.

[0064] Then, the first dry film 301 may be developed to remove at least a portion of the first dry film 301. The area from which the first dry film 301 has been at least partially removed may be a location where the pad 120 will be formed later. The process of exposing and developing the first dry film 301 may be performed using a method available to a person having ordinary skill in the art.

[0065] 7, a second metal layer 122 may be formed in an area where at least a portion of the first dry film 301 has been removed. The step of forming the second metal layer 122 may be performed by electrolytic plating, in which case the electrolytic plating may be performed using the first metal layer 121 as a seed. In the step of forming the second metal layer 122, the first dry film 301′ may function as a plating resist.

[0066] Thereafter, a second dry film 302 may be formed on the first dry film 301'. The second dry film 302 may have the same characteristics as the first dry film 301, but is not limited thereto, and the second dry film 302 may include a different type of photosensitive insulating material than the first dry film 301. Meanwhile, in FIG. 7, the second dry film 302 is shown disposed on the first dry film 301, but is not limited thereto, and may include a step of removing the first dry film 301 before forming the second dry film 302. In this case, the second dry film 302 may be formed on the first insulating layer 110 after the first dry film 301 is removed.

[0067] Then, a portion of the second dry film 302 can be exposed to light. At this time, the portion of the second dry film 302 can be exposed to light taking into consideration the position where the protrusion is to be formed.

[0068] A portion of the second dry film 302 may then be developed to remove at least a portion of the second dry film 302 .

[0069] Then, the protrusion 130 may be formed in the area where the second dry film 302 has been removed. The step of forming the protrusion 130 may be performed by electrolytic plating, but is not limited thereto. When the protrusion 130 is formed by electrolytic plating, electrolytic plating may be performed on the second metal layer 122 using the first metal layer 121 as a seed. At this time, the second dry film 302' deformed by exposure and development may function as a plating resist. Since the protrusion 130 is further formed immediately after the second metal layer 122 is formed on the first metal layer 121, the first metal layer 121 may be used as a seed for electrolytic plating. However, the method is not limited thereto, and the protrusion 130 may be formed by a method of attaching a metal material. Meanwhile, when the protrusion 130 does not include a metal material, the protrusion 130 may be formed in the opening area of ​​the second dry film 302' by various other methods such as printing, liquid coating, and hardening. Alternatively, the second dry film 302 may be made to contain a positive-type photosensitive insulating material, and the second dry film 302 may be patterned to correspond to the protrusions 130 .

[0070] 8, the first dry film 301′ and the second dry film 302′ can be removed. As a method for removing the dry films, a method available to a person having ordinary skill in the art can be used.

[0071] Thereafter, a third dry film 303 may be formed on the first insulating layer 110. The third dry film 303 may include a photosensitive insulating material, and a known dry film resist may be used. The description of the first dry film 301 may also be applied to the third dry film 303, and therefore a duplicate description will be omitted. The third dry film 303 formed on the first insulating layer 110 may mean that the third dry film 303 may be disposed on the first metal layer 121 formed on the first insulating layer 110, and may be formed to cover the second metal layer 122 and the protrusion 130. That is, the thickness of the third dry film 303 may be formed to be thicker than the thickness from the lower surface of the second metal layer 122 to the upper surface of the protrusion 130. The third dry film 303 is for forming a metal post, and the thickness may be adjusted in consideration of the height of the metal post.

[0072] Then, a portion of the third dry film 303 may be exposed to light. At this time, the exposure may be performed taking into consideration the area where the metal post 140 is to be formed, and at this time, a portion of the third dry film 303 may be deformed. The area of ​​the third dry film 303′ that is deformed by exposure may correspond to the protrusion 130. The fact that the area of ​​the third dry film 303′ may correspond to the protrusion 130 may mean that the center of the exposed area of ​​the third dry film 303′ may be located at the center of the protrusion 130, or may mean that the width of the exposed area of ​​the third dry film 303′ may be formed to be wider than the width of the protrusion 130.

[0073] Referring to FIG. 9, the third dry film 303 may be developed to remove the third dry film 303′ region, thereby forming an opening. The opening formed in the third dry film 303 may correspond to a region for forming the metal post 140. At this time, the step of developing the third dry film 303 may be performed by injecting a liquid type developer. Since the protrusion 130 is disposed under the third dry film 303′ region deformed by exposure, the developer can be injected along the protrusion 130 due to the injection pressure generated when injecting the developer. In the step of developing the third dry film 303, the unexposed third dry film 303 region may also be removed, and thus the opening formed in the third dry film 303 may have an upward tapered shape. Since the third dry film 303 is developed by injecting the developer, an opening having an upward tapered shape may be formed without a multiple layer structure, and an opening having an upward tapered shape may be formed without a process of inverting the top and bottom surfaces.

[0074] Thereafter, the metal post 140 is formed on the second metal layer 122. The metal post 140 may be formed to fill the opening formed in the third dry film 303, and may be formed by electrolytic plating, but is not limited to this. When the metal post 140 is formed by electrolytic plating, electrolytic plating may be performed on the second metal layer 122 using the first metal layer 121 as a seed. At this time, the metal post 140 may be formed to cover the protrusion 130, and the third dry film 303 may function as a plating resist.

[0075] Thereafter, the third dry film 303 can be removed. As a method for removing the dry film, any method available to a person having ordinary skill in the art can be used.

[0076] Then, at least a portion of the first metal layer 121 can be removed. As a method for removing the portion of the first metal layer 121, a known method for removing a seed layer, such as etching, can be used, and a method available to a person having ordinary skill in the art can be used. By removing at least a portion of the first metal layer 121, the pad 120 consisting of the first metal layer 121 and the second metal layer 122 is completed, and can be used as a signal path together with the metal post 140.

[0077] 10, a solder resist layer 160 may be formed on the first insulating layer 110. The method of forming the solder resist layer 160 may include applying an insulating material of the solder resist layer 160′, curing a portion of the insulating material, and removing the remaining portion of the insulating material.

[0078] Since the metal posts 140 of the printed circuit board according to the example have a protruding structure, it is preferable to use a liquid material for the solder resist layer 160. When a liquid material is used as the solder resist layer 160, unlike a film-like solder resist, a heat and pressure process is not required, which has the advantage that the metal posts 140 are not deformed.

[0079] After applying the liquid solder resist 160', the regions corresponding to the pads 120 and the metal posts 140 can be exposed and developed to form openings 160O. At least a portion of the pads 120 and the metal posts 140 can be exposed through the openings 160O of the solder resist layer 160.

[0080] 11, a surface treatment layer 150 can be formed on at least a portion of the pad 120 exposed through the opening 160O and on the metal post 140. The method for forming the surface treatment layer 150 may vary depending on the material and structure of the surface treatment layer 150, but a person having ordinary skill in the art can use any method available.

[0081] Thereafter, the height of the metal posts 140 can be adjusted to be uniform using the tool 400. That is, the upper surface of the metal posts 140 can be flattened using the tool 400. The tool 400 may be a substrate processing apparatus for coining, and the height of the metal posts 140 can be adjusted to be uniform using a pressure device attached to the tool 400. By adjusting the height of the metal posts 140 so that the heights of the metal posts 140 are substantially equal to each other, the defect rate can be reduced in the subsequent step of forming a connecting member, which can be advantageous when mounting a semiconductor chip. In addition, since the area of ​​the upper surface of the metal posts 140 can also be adjusted in this process, it can be adjusted to match the size design of the connecting member 170.

[0082] Referring to FIG. 12, a fourth dry film 304 may be formed on the solder resist layer 160. The fourth dry film 304 may be used as a means for aligning the metal post 140 in the step of forming the connecting member 170. The fourth dry film 304 may include a photosensitive insulating material, and a known dry film resist may be used. The description of the first dry film 301 and the third dry film 303 may also be applied to the fourth dry film 304, and therefore, the description will not be repeated. Since the fourth dry film 304 is disposed on the solder resist layer 160 including the photosensitive insulating material, it is preferable that the fourth dry film 304 uses a material that is more sensitive to peeling than the solder resist layer 160. In this case, the thickness of the fourth dry film 304 may be thicker than the thickness of the metal post 140. The fourth dry film 304 should be disposed so as to cover the metal post 140, and the thickness of the fourth dry film 304 being thicker than the thickness of the metal post 140 means that the upper surface of the fourth dry film 304 may be located higher than the upper surface of the metal post 140.

[0083] After that, exposure is performed on a portion of the fourth dry film 304. Since the fourth dry film 304 includes a photosensitive insulating material, deformation may occur in the fourth dry film 304' in the exposed area.

[0084] Thereafter, the fourth dry film 304 is developed to remove the fourth dry film 304' region, thereby forming an opening. The step of developing the fourth dry film 304 may also use a method of injecting a liquid type developer. At this time, since the developer can be injected along the outer surface of the metal post 140, the opening formed in the fourth dry film may also have an upward tapered shape. However, this is not necessarily limited thereto, and the opening formed in the fourth dry film may be formed such that the width of the upper side and the width of the lower side are substantially equal. Since developing the fourth dry film 304' to form an opening corresponds to an alignment for forming the connecting member, the width of the upper surface of the opening may be wider than the width of the upper surface of the metal post 140. At this time, the width of the upper surface of the opening may be formed in consideration of the design of the connecting member 170, and the width of the upper surface of the metal post 140 and the width and size of the connecting member 170 should be considered, and the design may be made in consideration of the process capacity, processing resolution, and the like.

[0085] 13, the connecting member 170 is formed on the metal post 140 through the opening formed in the fourth dry film 304. Forming the connecting member 170 on the metal post 140 may have the same meaning as forming the connecting member 170 on the surface treatment layer 150 disposed on the metal post 140. The step of forming the connecting member 170 may include a process of forming a viscous flux on the surface treatment layer 150, disposing the connecting member 170, and then performing reflow. Meanwhile, the process is not necessarily limited to the above, and any process may be used without limitation as long as the connecting member 170 can be disposed on the metal post 140 in the form of a ball.

[0086] Thereafter, the fourth dry film 304 is removed. Because the solder resist layer 160 and the fourth dry film 304 may each contain a photosensitive insulating material, a problem may occur in that a part of the solder resist layer 160 is also removed when the fourth dry film 304 is removed. To prevent this, as described above, the fourth dry film 304 may be designed to contain a material that is more sensitive to peeling than the solder resist layer 160. That is, because the fourth dry film 304 is more easily peeled off than the solder resist layer 160, it is possible to remove only the fourth dry film 304.

[0087] Meanwhile, as described above, the method for manufacturing a printed circuit board according to an example is not limited to the contents shown in Figures 6 to 13. Other components may be further included on the lower surface of the first insulating layer 110, as described above in the configuration of the printed circuit board according to an example.

[0088] In addition, the printed circuit board according to the other example may further include mounting the semiconductor chip 200 on the connection member 170 of the printed circuit board according to the example.

[0089] In the present invention, the term "on a cross section" may refer to the cross-sectional shape of an object cut vertically or the cross-sectional shape of an object when viewed from the side, and the term "on a plane" may refer to the shape of an object cut horizontally or the planar shape of an object when viewed from the top or bottom.

[0090] In the present invention, for convenience, the terms "upper side, upper part, top surface" and the like are used to mean a direction toward a surface on which an electronic component can be mounted based on a cross section of a drawing, and the terms "lower side, lower part, bottom surface" and the like are used to mean the opposite direction. However, this is a definition of the direction for convenience of explanation, and it goes without saying that the scope of the claims is not particularly limited by the description of the direction.

[0091] In the present invention, "connected" is a concept including not only direct connection but also indirect connection via an adhesive layer or the like. Furthermore, "electrically connected" is a concept including both physical connection and no connection. Furthermore, expressions such as "first, second" are used to distinguish one component from another component, and do not limit the order and / or importance of the components. In some cases, the first component may be named the second component, and similarly, the second component may be named the first component, within the scope of the right.

[0092] In the present invention, the term "substantially" can be determined by taking into account process errors, positional deviations, measurement errors, etc. that occur during the manufacturing process. For example, "substantially perpendicular" can include not only a completely perpendicular case, but also a nearly perpendicular case. Furthermore, "substantially coplanar" can include not only a completely coplanar case, but also a nearly coplanar case.

[0093] In the present invention, the same material can mean not only the completely same material, but also the same type of material. Thus, although the composition of the materials is substantially the same, the specific composition ratios thereof may differ slightly.

[0094] The term "one example" used in the present invention does not mean the same embodiment, but is provided to emphasize and describe the unique features that are different from each other. However, the above-mentioned one example does not exclude being realized in combination with the features of another example. For example, even if the matter described in a specific example is not described in another example, it can be understood as a description related to the other example, unless there is a description in the other example that is opposite or contradictory to the matter.

[0095] The terms used in the present invention are merely used to describe an example and are not intended to limit the present invention. In this case, the singular expression includes the plural expression unless the context clearly indicates otherwise. [Explanation of symbols]

[0096] 110: First insulating layer 120: Pad 121: 1st metal layer 122: Second metal layer 130:Protrusion 140: Metal post 150: Surface treatment layer 160: Solder resist layer 160O: opening 170: Connecting member 200: Semiconductor chips 201: Main body 202: Connection pad 301, 302, 303, 304: Dry film 400: Equipment 1000:Electronic equipment 1010: Main board 1020: Chip related parts 1030: Network related parts 1040:Other parts 1050: Camera module 1060: Antenna module 1070:Display 1080: Battery 1090: Signal line 1100: Smartphone 1110: Main board inside a smartphone 1120: Electronic components inside smartphones 1121: Antenna module inside a smartphone 1130: Camera module inside a smartphone 1140: Speaker inside smartphone

Claims

1. A first insulating layer; a pad disposed on the first insulating layer; a protrusion disposed on the pad; a metal post disposed on the pad and covering the protrusion; The metal post has a tapered shape such that the width of the upper surface is narrower than the width of the lower surface.

2. The printed circuit board of claim 1 , wherein the width of the metal post is narrower than the width of the pad.

3. The printed circuit board of claim 1 further comprising a solder resist layer disposed on the first insulating layer.

4. The printed circuit board of claim 3 , wherein the solder resist layer has openings that expose at least a portion of the pads and at least a portion of the metal posts.

5. The printed circuit board of claim 1 , further comprising a surface treatment layer covering at least a portion of the top surface of the pad and at least a portion of the metal post.

6. 2. The printed circuit board of claim 1, wherein the pad comprises a first metal layer disposed on the first insulating layer and a second metal layer disposed on the first metal layer.

7. The printed circuit board of claim 1 , wherein the protrusion comprises a metallic material.

8. The printed circuit board of claim 1 , further comprising a connecting member disposed on the metal post.

9. a semiconductor chip disposed on the metal post, the semiconductor chip including a body and a connection pad; The printed circuit board according to claim 8 , wherein the connecting member connects the metal post and the semiconductor chip to each other.

10. The printed circuit board according to claim 9 , wherein the connecting member has a width on the connection pad side greater than a width on the metal post side.

11. forming a pad on the first insulating layer; forming a protrusion on the pad; forming a metal post on the pad so as to cover the protrusion; The metal post has a tapered shape such that the width of the upper surface is narrower than the width of the lower surface.

12. 12. The method of claim 11, wherein the forming of the metal post is performed by forming a dry film on the first insulating layer, exposing and developing at least a portion of the dry film to expose at least a portion of the pad and at least a portion of the protrusion, and forming a metal post on the pad.

13. 13. The method of claim 12, wherein developing at least a portion of the dry film includes injecting a developer including a liquid material to form an opening having a tapered shape such that a width of an upper surface is narrower than a width of a lower surface.

14. forming the pad includes forming a first metal layer on the first insulating layer by electroless plating, and forming a second metal layer on the first metal layer by electrolytic plating; forming the protrusions includes forming the protrusions on the second metal layer by electrolytic plating; The method of claim 11 , wherein forming the metal post comprises forming the metal post on the second metal layer by electrolytic plating.

15. The method for manufacturing a printed circuit board according to claim 11, further comprising the step of forming a connecting member on the metal post after the step of forming the metal post.

16. The method for manufacturing a printed circuit board according to claim 15, further comprising the step of planarizing the metal post before the step of forming the connecting member.

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