Printed circuit board and method for manufacturing the same

Abstract

To provide a printed circuit board and a method for manufacturing the same that can enhance the contact characteristics of a connection section connected to a pad section of the printed circuit board.SOLUTION: A printed circuit board of the present invention comprises a first insulating layer, a pad section located above the first insulating layer, a connection section including a protruding section located above the pad section and a first recess located inside the protruding section, and a second insulating layer located over a portion of the pad section and exposing a portion of the connecting section, and the first height of the first recess of the connecting section, from the first insulating layer, is higher than the second height of the second insulating layer located on the side of the connecting section.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] 2. Description of the Related Art As electronic devices in the IT field, including mobile phones, become smaller, the size of metal posts formed on printed circuit boards on which electronic components are mounted is also becoming smaller.

[0003] As the size of the metal posts of the printed circuit board decreases, the adhesion between the metal posts of the printed circuit board and the semiconductor chip mounted on the printed circuit board may decrease. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-145462 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above-mentioned problems in the conventional art, and an object of the present invention is to provide a printed circuit board and a manufacturing method thereof that improves contact characteristics of a connection portion connected to a pad portion of the printed circuit board. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, one aspect of the present invention provides a printed circuit board comprising a first insulating layer, a pad portion located on the first insulating layer, a connecting portion located on the pad portion and including a protrusion and a first recess located inside the protrusion, and a second insulating layer located on a portion of the pad portion and exposing a portion of the connecting portion, wherein a first height of the first recess of the connecting portion from the first insulating layer is higher than a second height of the second insulating layer located on a side of the connecting portion.

[0007] The first recess of the coupling portion may protrude above the second insulating layer. The coupling portion may further include a second recess located along an edge of the protrusion. The protrusion may surround the first recess and the second recess may surround the protrusion. A third height of the second recess from the first insulating layer may be greater than the second height of the second insulating layer. An outer planar shape of the protrusion of the connection portion and an outer planar shape of the first recess may be identical. The outer planar shape of the protrusion of the connection portion and the outer planar shape of the first recess may be circular. An outer planar shape of the protrusion of the connection portion and an outer planar shape of the first recess may be different from each other. The projection of the connecting portion may have a circular outer planar shape, and the first recess may have a rectangular outer planar shape. The first recess may have an outer planar shape of an ellipse. The first height of the first recess may decrease from the protruding portion to a center of the connecting portion. The first height of the first recess may be a minimum height of the first recess.

[0008] In order to achieve the above object, a method for manufacturing a printed circuit board according to one aspect of the present invention includes the steps of: forming a pad portion on a first insulating layer; forming a first photosensitive film on the pad portion, the first photosensitive film having a first hole overlapping the pad portion; laminating a metal layer in the first hole of the first photosensitive film; forming a second photosensitive film having a second hole overlapping a portion of the metal layer; and treating the metal layer to form a connecting portion including a protrusion and a first recess located inside the protrusion.

[0009] The second photosensitive film may be formed after removing the first photosensitive film. The second hole of the second photosensitive film may be formed to correspond to the protrusion of the connection part. In the metal layer processing step, a metal layer may be laminated on the metal layer so as to fill the second hole. The connecting portion may further include a second recess located along an edge of the protruding portion, and the second hole of the second photosensitive film may be formed so as not to overlap the second recess. The second photosensitive film may be formed on the first photosensitive film, and a width of the second hole of the second photosensitive film may be narrower than a width of the first hole of the first photosensitive film. In the step of treating the metal layer, the metal layer exposed by the second hole of the second photoresist film may be etched to form the first recess. Effect of the Invention

[0010] Advantageous Effects of Invention According to the present invention, it is possible to provide a printed circuit board and a manufacturing method thereof that can improve contact characteristics of a connection portion connected to a pad portion of the printed circuit board. [Brief description of the drawings]

[0011] [Figure 1] 1 is a simplified cross-sectional view of a printed circuit board according to one embodiment. [Diagram 2] FIG. 2 is a plan view of a portion of FIG. [Diagram 3] FIG. 2 is a plan view of a portion of FIG. [Figure 4] FIG. 2 is a plan view of a portion of FIG. [Diagram 5] 1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 6] 1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 7] 1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 8] 1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 9] 1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 10]1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 11] 1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 12] 1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 13] 1A to 1C are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment. [Figure 14] 1 is a simplified cross-sectional view of a printed circuit board according to another embodiment. [Figure 15] FIG. 15 is a plan view of a portion of FIG. [Figure 16] FIG. 15 is a plan view of a portion of FIG. [Figure 17] FIG. 15 is a plan view of a portion of FIG. [Figure 18] 10A to 10C are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to another embodiment. [Figure 19] 10A to 10C are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to another embodiment. [Figure 20] 10A to 10C are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to another embodiment. [Figure 21] 10A to 10C are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to another embodiment. [Figure 22] 10A to 10C are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to another embodiment. [Figure 23] 10A to 10C are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to another embodiment. [Figure 24] 10A to 10C are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to another embodiment. [Diagram 25] 10A to 10C are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be embodied in various different forms and should not be construed as being limited to the embodiments set forth herein.

[0013] In order to clearly explain the present invention, parts that are not necessary for the explanation are omitted, and the same reference numerals are used throughout the specification to refer to the same or similar components.

[0014] Furthermore, the drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the drawings do not limit the technical ideas disclosed in this specification, and it should be understood that the drawings include any modifications, equivalents, or alternatives included in the idea and technical scope of the present invention.

[0015] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, thicknesses are enlarged to clearly show various layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0016] Furthermore, when a part such as a layer, film, region, or plate is said to be "on" or "above" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. Furthermore, being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "on" or "above" the opposite direction of gravity.

[0017] In addition, throughout the specification, when a part is said to "comprise" a certain element, this means that it may further include other elements, not excluding other elements, unless specifically stated to the contrary.

[0018] Furthermore, throughout the specification, the term "on a plane" means the part in question viewed from above, and the term "on a cross section" means the part in question cut vertically and viewed from the side.

[0019] In addition, throughout the specification, when the term "connected" is used, it does not only mean that two or more components are directly connected, but also that two or more components are indirectly connected via other components, that they are not only physically connected but also electrically connected, or that they are referred to by different names depending on their location or function but are integrated.

[0020] Hereinafter, various embodiments and modifications will be described in detail with reference to the drawings.

[0021] A printed circuit board according to an embodiment will be described with reference to Figures 1 and 2 to 4. Figure 1 is a simplified cross-sectional view of a printed circuit board according to an embodiment, and Figures 2 to 4 are plan views of a portion of Figure 1.

[0022] Referring to FIG. 1, the printed circuit board according to the present embodiment includes a first insulating layer SUB, a pad portion ML located on the first insulating layer SUB, a connecting portion SB located on the pad portion ML, and a second insulating layer CL covering a portion of the pad portion ML and a portion of the connecting portion SB.

[0023] The connecting portion SB includes a protruding protrusion SBP, a first recess SBC on the inner side of the protrusion SBP, and a second recess SBE on the outer side of the protrusion SBP.

[0024] The connecting portion SB protrudes above the second insulating layer CL and is connected to an external element.

[0025] The upper surfaces of the first recess SBC and the second recess SBE of the connecting portion SB as well as the protrusion SBP of the connecting portion SB protrude above the second insulating layer CL.

[0026] A first height Ha of the first recess SBC and the second recess SBE of the coupling portion SB measured from the first insulating layer SUB is greater than a second height Hb of the second insulating layer CL located on the side surface of the coupling portion SB.

[0027] In this manner, the first recess SBC and second recess SBE of the connecting portion SB protrude from the second insulating layer CL so that the first height Ha of the first recess SBC and second recess SBE of the connecting portion SB measured from the first insulating layer SUB is higher than the second height Hb of the second insulating layer CL located on the side of the connecting portion SB, and during the manufacturing process, the second insulating layer CL is completely removed without remaining on the first recess SBC and second recess SBE of the connecting portion SB.

[0028] The bottom surface of the connection portion SB contacts the pad portion ML to electrically connect the printed circuit board to an external device.

[0029] The second insulating layer CL includes an upwardly protruding portion CLP, but the protruding portion CLP can be omitted.

[0030] The second insulating layer CL includes a solder resist, but the embodiment is not limited thereto.

[0031] Although not shown, the pad unit ML is located under the first insulating layer SUB through a via formed in the first insulating layer SUB, or is connected to an additional wiring layer buried in the first insulating layer SUB.

[0032] Referring to FIG. 2 together with FIG. 1, the outer planar shape of the edge of the protrusion portion SBP of the connection portion SB of the printed circuit board according to one embodiment is substantially the same as the outer planar shape of the edge of the first recess SBC and the outer planar shape of the edge of the second recess SBE.

[0033] The outer planar shape of the protrusion SBP of the connecting portion SB and the outer planar shape of the first recess SBC and the outer planar shape of the second recess SBE are substantially circular in plan view, but may be substantially elliptical in plan view.

[0034] Referring to FIG. 3, according to one embodiment, an outer edge of a connecting portion SB of a printed circuit board has a substantially circular outer planar shape, a first recess SBC has a rectangular outer planar shape, and a second recess SBE of the connecting portion SB has a substantially circular outer planar shape.

[0035] Referring to FIG. 4, according to one embodiment, an outer edge of a connection portion SB of a printed circuit board has a substantially circular outer planar shape, a first recess SBC has an elliptical outer planar shape, and a second recess SBE of the connection portion SB has a substantially circular outer planar shape.

[0036] The outer planar shapes of the protrusion SBP of the connecting portion SB, the first recess SBC, and the second recess SBE can be modified in various ways.

[0037] The connecting portion of the printed circuit board according to this embodiment includes a protrusion SBP protruding upward, a first recess SBC inside the protrusion SBP, and a second recess SBE outside the protrusion SBP. Therefore, the surface area of ​​the connecting portion SB protruding above the second insulating layer CL is larger than when the connecting portion SB is a single pillar shape not including the first recess SBC and the second recess SBE.

[0038] Therefore, according to the present embodiment, the surface area of ​​the connecting part SB protruding above the surface of the second insulating layer CL is increased, so that the contact area between the external element and the connecting part SB is relatively increased, thereby reducing the shear stress between the external element and the connecting part SB, increasing the adhesion between the external element and the connecting part SB, and reducing the contact resistance between the external element and the connecting part SB, thereby reducing the loss of the electrical signal and reducing the electrical resistance.

[0039] A method for manufacturing a printed circuit board according to an embodiment will be described with reference to Figures 5 to 13 together with Figures 1 to 4. Figures 5 to 13 are simplified cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment.

[0040] Referring to FIG. 5, a pad portion ML is formed on a first insulating layer SUB, and referring to FIG. 6, a first photosensitive film DF1 is laminated on the pad portion ML.

[0041] The first photosensitive film DF1 has photosensitivity and is a dry film, but the embodiment is not limited thereto.

[0042] As shown in FIG. 7, a first hole HL1 overlapping the pad portion ML is formed in a first photosensitive film DF1.

[0043] The first hole HL1 of the first photosensitive film DF has a columnar shape that is occupied by the protrusion SBP of the connection portion SB, the first recess SBC, and the second recess SBE.

[0044] Referring to FIG. 8, a metal layer is formed in the first hole HL1 of the first photosensitive film DF1 to form the first portion SB1 of the connecting part SB.

[0045] Referring to FIG. 9, the first photosensitive film DF1 is removed, and a second photosensitive film DF2 is laminated on the first portion SB1 of the connecting portion SB.

[0046] 10, a second hole HL2 is formed in the second photosensitive film DF2 in an area where the protrusion SBP of the connecting part SB is to be formed, and the planar shape of the second hole HL2 is the same as the planar shape of the protrusion SBP of the connecting part SB.

[0047] In FIG. 10, of the first portion SB1 of the connecting portion SB, the middle portion that does not overlap with the second hole HL2 of the second photosensitive film DF2 corresponds to the first recess SBC of the connecting portion SB, and the edge portion that does not overlap with the second hole HL2 of the second photosensitive film DF2 corresponds to the second recess SBE of the connecting portion SB.

[0048] Referring to FIG. 11, a metal layer is laminated on the first portion SB1 of the connecting portion SB overlapping the second hole HL2 of the second photosensitive film DF2 to form a protrusion SBP of the connecting portion SB located within the second hole HL2 of the second photosensitive film DF2, thereby forming the connecting portion SB including the protrusion SBP, the first recess SBC and the second recess SBE.

[0049] Referring to FIG. 12, the second photosensitive film DF2 is removed.

[0050] Referring to FIG. 13, an insulating layer CL1 is laminated on the connecting portion SB.

[0051] Thereafter, a portion of the insulating layer CL1 is removed to form a second insulating layer CL that exposes the protrusion SBP of the connecting portion SB, the first recess SBC, and the second recess SBE, thereby completing the printed circuit board of FIG.

[0052] At this time, the first height Ha of the first recess SBC and the second recess SBE of the coupling portion SB measured from the first insulating layer SUB is higher than the second height Hb of the second insulating layer CL located on the side surface of the coupling portion SB. Therefore, the insulating layer CL1 above the first recess SBC and the second recess SBE of the coupling portion SB is entirely removed.

[0053] According to the method for manufacturing a printed circuit board according to the present embodiment, the connecting portion SB is formed to include a protruding protrusion SBP, a first recess SBC inside the protrusion SBP, and a second recess SBE outside the protrusion SBP. As a result, the surface area of ​​the connecting portion SB protruding above the second insulating layer CL is wider than when the connecting portion SB is a single pillar shape not including the first recess SBC and the second recess SBE.

[0054] Therefore, according to the present embodiment, the surface area of ​​the protrusion SBP of the connecting part SB protruding above the surface of the second insulating layer CL and the first and second recesses SBC and SBE of the connecting part SB is increased, so that the contact area between the external element and the connecting part SB is relatively increased, thereby reducing the shear stress between the external element and the connecting part SB, increasing the adhesion between the external element and the connecting part SB, and reducing the contact resistance between the external element and the connecting part SB, thereby reducing the loss of the electrical signal and reducing the electrical resistance.

[0055] A printed circuit board according to another embodiment will be described with reference to Fig. 14 and Fig. 15 to Fig. 17. Fig. 14 is a simplified cross-sectional view of a printed circuit board according to another embodiment, and Fig. 15 to Fig. 17 are plan views of a portion of Fig. 14.

[0056] 14, the printed circuit board according to the present embodiment is similar to the printed circuit board according to the embodiment shown in Fig. 1. Detailed description of the same components will be omitted.

[0057] Referring to FIG. 14, the printed circuit board according to this embodiment includes a first insulating layer SUB, a pad portion ML located on the first insulating layer SUB, a connecting portion SB located on the pad portion ML, and a second insulating layer CL covering a portion of the pad portion ML and a portion of the connecting portion SB.

[0058] The connecting portion SB includes a recess SBL formed in the center and having a low height, and a protrusion SBH surrounding the outer periphery of the recess SBL and having a high height.

[0059] The height of the recess SBL of the connecting portion SB is lowest at the center of the connecting portion SB and gradually increases toward the protruding portion SBH of the connecting portion SB.

[0060] The connecting portion SB protrudes above the second insulating layer CL and is connected to an external element.

[0061] Not only the protrusion SBH of the coupling portion SB but also the upper surface of the recess SBL of the coupling portion SB protrudes above the second insulating layer CL.

[0062] A third height Haa, which is the minimum height of the recess SBL of the coupling portion SB measured from the first insulating layer SUB, is higher than a second height Hb of the second insulating layer CL located on the side surface of the coupling portion SB.

[0063] In this manner, the recess SBL of the connecting portion SB protrudes from the second insulating layer CL so that the third height Haa, which is the minimum height of the recess SBL of the connecting portion SB measured from the first insulating layer SUB, is higher than the second height Hb of the second insulating layer CL located on the side of the connecting portion SB, and during the manufacturing process, none of the second insulating layer CL remains on the recess SBL of the connecting portion SB but is completely removed.

[0064] The bottom surface of the connection portion SB contacts the pad portion ML to electrically connect the printed circuit board to an external device.

[0065] The second insulating layer CL includes an upwardly protruding portion CLP, but the protruding portion CLP can be omitted.

[0066] The second insulating layer CL includes a solder resist, but the embodiment is not limited thereto.

[0067] Although not shown, the pad unit ML is located under the first insulating layer SUB through a via formed in the first insulating layer SUB, or is connected to an additional wiring layer buried in the first insulating layer SUB.

[0068] 15 together with FIG. 14, the protrusion SBH and the recess SBL of the connection part SB of the printed circuit board according to an embodiment have substantially the same planar shape.

[0069] The edge of the protrusion SBH of the connecting portion SB and the edge of the recess SBL have a substantially circular outer planar shape. However, differently from this, the edge of the protrusion SBH of the connecting portion SB and the edge of the recess SBL may have a substantially elliptical outer planar shape.

[0070] Referring to FIG. 16, an edge of a connection portion SB of a printed circuit board according to an embodiment has a substantially circular outer planar shape, while an edge of a recess SBL of the connection portion SB has a rectangular outer planar shape.

[0071] Referring to FIG. 17, an edge of a connection portion SB of a printed circuit board according to an embodiment has a substantially circular outer planar shape, while an edge of a recess SBL of the connection portion SB has a polygonal outer planar shape.

[0072] The outer planar shapes of the projection SBH and recess SBL of the connecting portion SB can be variously changed.

[0073] The connection portion SB of the printed circuit board according to this embodiment includes a protruding protrusion SBH and a recess SBL inside the protrusion SBH, and therefore the surface area of ​​the connection portion SB protruding above the second insulating layer CL is larger than when the connection portion SB is a single pillar shape without a recess SBL.

[0074] Therefore, according to the present embodiment, the surface area of ​​the connecting part SB protruding above the surface of the second insulating layer CL is increased, so that the contact area between the external element and the connecting part SB is relatively increased, thereby reducing the shear stress between the external element and the connecting part SB, increasing the adhesion between the external element and the connecting part SB, and reducing the contact resistance between the external element and the connecting part SB, thereby reducing the loss of the electrical signal and reducing the electrical resistance.

[0075] Many of the features of the printed circuit board according to the embodiment described above with reference to FIGS. 1 to 4 are all applicable to the printed circuit board according to this embodiment.

[0076] A method for manufacturing a printed circuit board according to another embodiment will be described with reference to Figures 18 to 25 together with Figures 14 to 17. Figures 18 to 25 are simplified cross-sectional views showing a method for manufacturing a printed circuit board according to another embodiment.

[0077] Referring to FIG. 18, a pad portion ML is formed on a first insulating layer SUB, and referring to FIG. 19, a first photosensitive film DF1 is laminated on the pad portion ML.

[0078] The first photosensitive film DF1 has photosensitivity and is a dry film, but the embodiment is not limited thereto.

[0079] As shown in FIG. 20, a first hole HL1 overlapping with a pad portion ML is formed in a first photosensitive film DF1.

[0080] The first hole HL1 of the first photosensitive film DF has a columnar shape that is occupied by both the protrusion SBH and the recess SBL of the connection portion SB.

[0081] Referring to FIG. 21, a metal layer is formed in the first hole HL1 of the first photosensitive film DF1 to form the first portion SB1 of the connecting part SB.

[0082] Referring to FIG. 22, a second photosensitive film DFA is formed on the first photosensitive film DF1, and a second hole HL2 is formed to expose a part of the first portion SB1 of the connecting portion SB.

[0083] The second hole HL2 is formed in the region where the recess SBL of the connecting portion SB is formed, and the planar shape of the second hole HL2 is the same as the planar shape of the recess SBL of the connecting portion SB. The size of the second hole HL2 is smaller than the size of the first hole HL1.

[0084] Referring to FIG. 23, the first portion SB1 of the connecting portion SB exposed by the second hole HL2 of the second photosensitive film DFA is etched to form a recess SBL of the connecting portion SB, thereby forming the connecting portion SB including a recess SBL located at the center and having a low height, and a protrusion SBH surrounding the outer edge of the recess SBL and having a high height.

[0085] Referring to FIG. 24, the second photoresist film DFA is removed.

[0086] Referring to FIG. 25, an insulating layer CL1 is laminated on the connecting portion SB.

[0087] Thereafter, a portion of the insulating layer CL1 is removed to form a second insulating layer CL that exposes the surfaces of the protrusions SBH and recesses SBL of the connecting portions SB, thereby completing the printed circuit board shown in FIG.

[0088] At this time, the third height Haa, which is the minimum height of the recess SBL of the coupling portion SB measured from the first insulating layer SUB, is higher than the second height Hb of the second insulating layer CL located on the side surface of the coupling portion SB. Therefore, the insulating layer CL1 above the recess SBL of the coupling portion SB is entirely removed.

[0089] According to the manufacturing method of the printed circuit board according to this embodiment, the connecting portion SB is formed to include the protrusion SBH and the recess SBL inside the protrusion SBH, so that the surface area of ​​the connecting portion SB protruding above the second insulating layer CL is wider than when the connecting portion SB is a single pillar shape not including the protrusion SBH and the recess SBL.

[0090] Therefore, according to the present embodiment, the surface area of ​​the protrusions SBH and recesses SBL of the connecting part SB protruding above the surface of the second insulating layer CL is increased, so that the contact area between the external element and the connecting part SB is relatively increased, thereby reducing the shear stress between the external element and the connecting part SB, increasing the adhesion between the external element and the connecting part SB, and reducing the contact resistance between the external element and the connecting part SB, thereby reducing the loss of electrical signals and reducing the electrical resistance.

[0091] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the technical spirit of the present invention. [Explanation of symbols]

[0092] CL Second insulating layer CL1 Insulation layer CLP protruding part DF1 1st photoresist film DF2, DFA 2nd photoresist film HL1, HL2 1st and 2nd halls ML Pad section SB connection part SB1 Part 1 SBC, SBE 1st and 2nd recesses SBL Recess SBH, SBP protrusion SUB 1st insulating layer

Claims

1. A first insulating layer; a pad portion located on the first insulating layer; a connecting portion including a protruding portion located on the pad portion and a first recess portion located inside the protruding portion; a second insulating layer located on a portion of the pad portion and exposing a portion of the connection portion; a first height of the first recess of the connection portion from the first insulating layer is greater than a second height of the second insulating layer located on a side of the connection portion.

2. The printed circuit board of claim 1 , wherein the first recess of the connection portion protrudes above the second insulating layer.

3. The printed circuit board of claim 2 , wherein the connecting portion further comprises a second recess located along an edge of the protruding portion.

4. The protrusion surrounds the first recess, The printed circuit board of claim 3 , wherein the second recess surrounds the protrusion.

5. 4. The printed circuit board of claim 3, wherein a third height of the second recess from the first insulating layer is greater than a second height of the second insulating layer.

6. The printed circuit board of claim 5 , wherein an outer planar shape of the protrusion of the connection portion is the same as an outer planar shape of the first recess.

7. The printed circuit board of claim 6 , wherein an outer planar shape of the protrusion of the connection portion and an outer planar shape of the first recess are circular.

8. The printed circuit board of claim 5 , wherein an outer planar shape of the protrusion of the connection portion and an outer planar shape of the first recess are different from each other.

9. The outer planar shape of the protrusion of the connecting portion is circular, The printed circuit board of claim 8, wherein the first recess has a rectangular planar outer shape.

10. The outer planar shape of the protrusion of the connecting portion is circular, The printed circuit board of claim 8 , wherein the first recess has an outer planar shape of an ellipse.

11. 3. The printed circuit board of claim 2, wherein the first height of the first recess decreases from the protrusion toward the center of the connection portion.

12. The printed circuit board of claim 11 , wherein the first height of the first recess is a minimum height of the first recess.

13. The printed circuit board of claim 12 , wherein the protrusion surrounds the first recess.

14. forming a pad portion on the first insulating layer; forming a first photoresist film on the pad portion, the first photoresist film having a first hole overlapping the pad portion; depositing a metal layer in the first hole of the first photosensitive film; forming a second photoresist film having a second hole overlapping a portion of the metal layer; and treating the metal layer to form a connecting portion including a protrusion and a first recess located inside the protrusion.

15. 15. The method of claim 14, wherein the second photoresist film is formed after removing the first photoresist film.

16. 16. The method of claim 15, wherein the second hole of the second photoresist film is formed to correspond to the protrusion of the connection part.

17. 17. The method of claim 16, wherein in the metal layer treating step, a metal layer is laminated on the metal layer so as to fill the second hole.

18. The coupling portion is formed to further include a second recess located along an edge of the protrusion, 18. The method of claim 17, wherein the second hole of the second photoresist film is formed so as not to overlap the second recess.

19. the second photosensitive film is formed on the first photosensitive film; 15. The method of claim 14, wherein a width of the second hole of the second photoresist film is narrower than a width of the first hole of the first photoresist film.

20. 20. The method of claim 19, wherein in the metal layer treating step, the metal layer exposed by the second hole of the second photoresist film is etched to form the first recess.

Images