TW201933958A - Printed circuit board - Google Patents

Abstract

According to an aspect of the present invention, there is provided a printed circuit board comprising: a metal pad formed on an insulating layer; a solder resist layer having an opening part for exposing at least a part of the metal pad and formed on the insulating layer; and a first metal post formed on the metal pad in the opening part and having an upper surface protruded above the surface of the solder resist layer, wherein an electroless plating layer is formed on the entire side surface and the lower surface of the first metal post.

Description

A printed circuit board

The following description is related to a printed circuit board.

Recently, bumps for mounting wafers on a printed circuit board have been formed with precise pitch. Techniques for forming bumps are Blue Stencil Printing (BSP) or u-ball technology, but due to technical limitations in these techniques, the formation of bump pitch is limited. In order to reduce the bump pitch, a different method from the conventional method is required. Therefore, an attempt has been made to form the bump into a shape including a metal column. [Related technology] Korea 10-2013-0135214 (2013.12.10)

It is an object of the present invention to provide a printed circuit board comprising posts having excellent matching.

According to an aspect of the present invention, there is provided a printed circuit board comprising: a metal pad formed on an insulating layer; a solder resist layer having an opening for exposing at least a portion of the metal pad, and Formed on the insulating layer; and a first metal pillar formed on the metal pad in the opening portion and having an upper surface protruding above a surface of the solder resist layer, wherein the first metal An electroless plating layer is formed on the entire side surface and the lower surface of the column.

The following detailed description is provided to assist the reader in a comprehensive understanding of the methods, devices and/or systems described herein. Various modifications, adaptations, and equivalents of the methods, devices, and/or systems described herein will be apparent to those skilled in the art. The order of operations described herein is merely an example, and is not limited to the order of operations referred to herein, but will be apparent to those of ordinary skill in the art, except where the operations must occur in a particular order. Other than that, it can be changed. In addition, descriptions of well-known functions and constructions of those skilled in the art can be omitted for clarity and clarity.

Features described herein can be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein are provided to be thorough and complete, and the full scope of the present invention will be conveyed to those of ordinary skill in the art.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning meaning meaning Any term defined in a commonly used dictionary should be interpreted as having the same meaning as in the context of the related art, and should not be construed as having an idealized or overly formal meaning unless explicitly defined otherwise.

Regardless of the figure number, the same or corresponding components will be given the same reference numerals, and the same or corresponding components will not be described again. Throughout the description of the present invention, the detailed description will be omitted when it is stated that the specific related conventional techniques are not related to the viewpoint of the present invention. Terms such as "first" and "second" may be used in the description of various components, but the above components should not be limited to the above terms. The above terms are only used to distinguish between components. In the figures, some components may be exaggerated, omitted or briefly shown, and the dimensions of the components do not necessarily reflect the actual dimensions of the components.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows a printed circuit board in accordance with an embodiment of the present invention.

Referring to FIG. 1, a printed circuit board according to an embodiment of the present invention includes an insulating layer 100, a metal pad 110, a solder resist layer 200, and a first metal pillar 300. The printed circuit board can further include a second metal post 400.

The printed circuit board can be formed in multiple layers. The printed circuit board may include a core 100' at the center of the printed circuit board and a build-up layer of insulating layers 100 and 100'' formed above and below the core 100'. The metal posts 300 and 400 are formed on the insulating layer 100 laminated above the core 100', and components such as wafers are mounted on the metal posts 300 and 400. An additive such as solder ball 500 is formed under the insulating layer 100'' laminated under the core 100', and the printed circuit board and the main board are bonded together.

The printed circuit board can be a coreless substrate without a core. Further, in this case, a metal pillar is formed on the insulating layer on the uppermost layer of the printed circuit board to mount the wafer, and a solder ball is formed on the insulating layer on the lowermost layer of the printed circuit board to be bonded to Motherboard.

The core 100' and/or the insulating layer 100 may be formed of an insulating material such as a resin and have a thin plate shape. The resin of the core 100' resin and/or the insulating layer 100 may be various materials such as a thermosetting resin or a thermoplastic resin, and specifically may be an epoxy resin or a polyimide. Examples of the epoxy resin include naphthalene epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and novolac epoxy. Novolac epoxy resin, cresol novolak epoxy resin, rubber modified epoxy resin, cycloaliphatic epoxy resin, lanthanum epoxy A silicon-based epoxy resin, a nitrogen-based epoxy resin, or a phosphorus-based epoxy resin. However, it is not limited to this.

The core 100' and/or the insulating layer 100 may be, for example, a prepreg (PPG) containing a fiber reinforcement material such as glass cloth in a resin. The insulating layer 100 may be, for example, a build-up film in which a resin is filled with an inorganic filler such as silica. As the constituent film, an Ajinomoto Build-up Film (ABF) or the like can be used.

The insulating layer 100 may be formed in a plurality of layers. A circuit 120 is formed in each of the insulating layers 100. Circuit 120 is a conductor that is patterned to transmit electrical signals. The circuit 120 can be electrically connected via the via 130. The outermost layer circuit 120' is formed on the uppermost insulating layer 100 and the outermost layer circuit 120' is electrically connected to the other circuit 120 via the via 130. The position of such outermost circuit 120' is not limited, and a portion of outermost circuit 120' may be located between a plurality of first metal posts 300 to be described later.

The circuit 120 and the outermost layer circuit 120' may be made of a metal such as copper (Cu), palladium (Pd), aluminum (Al), nickel (Ni), titanium (Ti), gold (Au), titanium (Pt), or an alloy thereof. form.

The metal pad 110 may be formed at an end part of the outermost layer circuit 120' and may have a width greater than the width of the outermost layer circuit 120'. The metal pad 110 may be formed on the via 130 and electrically connected to the circuit 120 formed in another layer.

The solder resist layer 200 is formed on the insulating layer 100 and has an opening portion 210 for exposing at least a portion of the metal pad 110 (as shown in FIG. 7 later). That is, the opening portion 210 of the solder resist layer 200 is formed on the metal pad 110, and the width of the region where the metal pad 110 is exposed through the opening portion 210 may be smaller than the width of the metal pad 110. In this case, the lower width of the first metal post 300 to be explained later is smaller than the width of the metal pad 110.

The solder resist layer 200 may be a photosensitive resin containing an inorganic filler such as cerium oxide, and the photosensitive resin may be an epoxy resin. However, the material is not limited to the materials, and any of the commonly used materials used in printed circuit boards can be used.

The solder resist layer 200 may be a positive type or a negative type, and the following description mainly describes a negative type, but does not exclude a positive type.

In the printed circuit board, the solder resist layer 200' is also laminated under the insulating layer 100'' laminated on the lower portion of the core 100'.

The first metal pillar 300 is a columnar metal formed on the metal pad 110 in the opening portion 210 of the solder resist layer 200. The first metal post 300 is used to mount the components and may be formed in plurality.

The upper surface of the first metal pillar 300 protrudes above the surface (upper surface) of the solder resist layer 200. That is, the solder resist layer 200 is formed lower than the first metal pillar 300.

The first metal pillar 300 may not contact the surface (upper surface) of the solder resist layer 200. The side slope of the first metal pillar 300 with respect to the surface of the solder resist layer 200 is greater than zero degrees. That is, the side surface of the first metal pillar 300 does not have a section in which the slope of the surface with respect to the solder resist layer 200 becomes zero (a section parallel to the surface of the solder resist layer 200).

An electroless plating layer 310 is formed on the entire side surface and the lower surface of the first metal pillar 300. That is, the electroless plating layer 310 is formed on the entire outer circumferential surface of the first metal pillar 300, and the electroless plating layer 310 is also formed on the lower surface of the first metal pillar 300.

The electroless plating layer 310 formed on the side surface of the first metal pillar 300 contacts the solder resist layer 200. Therefore, the width (area) of the opening portion 210 of the solder resist layer 200 on the surface of the solder resist layer 200 is equal to the width (area) of the first metal pillar 300 including the electroless plating layer 310.

An electroless plating layer 310 formed on the lower surface of the first metal pillar 300 is formed on the upper surface of the metal pad 110. That is, the electroless plating layer 310 is formed between the first metal pillar 300 and the metal pad 110. Here, the first metal pillar 300 may be formed of a plating layer by the electroless plating layer 310 being a lead-in wire.

The first metal pillar 300 protrudes beyond the solder resist layer 200. Since the electroless plating layer 310 is formed on the entire side surface of the first metal pillar 300, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 is exposed to the outside.

The electroless plating layer 310 may be formed of the same metal as the first metal pillar 300. For example, both the first metal pillar 300 and the electroless plating layer 310 may be formed of copper (Cu). On the other hand, the electroless plating layer 310 is not necessarily formed of the same metal as the first metal pillar 300, but may be formed of two layers. The electroless plating layer 310 may be formed of two layers of a metal including the same metal as the first metal pillar 300. For example, the first metal pillar 300 may be formed of copper (Cu), and the electroless plating layer 310 may be formed of a two-layer structure composed of a titanium (Ti) layer and a copper (Cu) layer. Here, the electroless plating layer 310 of titanium may be formed on the outermost layer and may be exposed to the outside. However, it does not exclude the case where a copper (Cu) layer is formed on the outermost layer of the electroless plating layer 310.

The electroless plating layer 310 is formed by electroless plating and can be formed to have a thickness of 2 micrometers (μm) or less.

A second metal post 400 may be formed on the first metal post 300. The melting point of the metal forming the second metal pillar 400 is lower than the melting point of the metal forming the first metal pillar 300. For example, the first metal pillar 300 may be formed of copper and the second metal pillar 400 may be formed of tin (Sn).

The second metal post 400 is used to bond the first metal post 300 to the assembly. The second metal pillar 400 is formed of a metal having a lower melting point than the first metal pillar 300 such that the second metal pillar 400 is melted before the first metal pillar 300 is melted in a reflow process.

The second metal pillar 400 may be formed to have a thinner thickness than the first metal pillar 300 by plating. The second metal post 400 flows to the left and right by a reflow process, and the upper surface of the second metal post 400 may be a curved surface that protrudes upward.

Hereinafter, the first to fifth embodiments will be explained in accordance with the shape of the first metal post 300 and the position of the second metal post 400. The insulating layer 100 on the uppermost layer of the printed circuit board is shown in FIGS. 2 to 41, and the layer formed under the insulating layer 100 is omitted.

Figure 2 shows a printed circuit board in accordance with a first embodiment of the present invention.

Referring to FIG. 2, in the printed circuit board according to the first embodiment, the area of the first metal pillar 300 is substantially constant from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300. change. The width of the first metal post 300 is also substantially constant from the upper surface of the first metal post 300 to the lower surface of the first metal post 300. Here, "substantially constant" means that the width is constant under conditions including tolerance. The first metal post 300 may be formed in a cylindrical shape or a polygonal shape.

When A is the width of the metal pad 110, B is the width of the first metal post 300 on the surface of the solder resist layer 200, C is the width of the upper surface of the first metal post 300, and D is the lower side of the first metal post 300 When the width of the surface is satisfied, the following formula holds, and is true even when the width is replaced by the area.

A>B=C=D

If the thickness of the electroless plating layer 310 is included in B, C, and D, the following formula can be established.

A≥B=C=D

The second metal pillar 400 is formed on the first metal pillar 300, and the electroless plating layer 310 formed on the side surface of the first metal pillar 300 extends to the side surface of the second metal pillar 400. However, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover at least a portion of the side surface of the second metal pillar 400. That is, as shown in FIG. 2, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover only a portion of the side surface of the second metal pillar 400. In this case, a portion of the second metal pillar 400 is over the electroless plating layer 310 such that the second metal pillar 400 protrudes beyond the electroless plating layer 310. Here, the second metal post 400 has a mushroom shape.

Alternatively, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover the entire side surface of the second metal pillar 400. In this case, the second metal post 400 may not protrude beyond the electroless plating layer 310 formed on the side surface of the metal post 300.

Figure 3 shows a printed circuit board in accordance with a second embodiment of the present invention.

Referring to FIG. 3, in the printed circuit board according to the second embodiment, the cross-sectional area of the first metal pillar 300 becomes smaller from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300. The width of the first metal post 300 also becomes smaller from the upper surface of the first metal post 300 to the lower surface of the first metal post 300. The cross section of the first metal post 300 may be an inverted trapezoidal column. In this case, the component mounting area is widened to enable stable component mounting.

When A is the width of the metal pad 110, B is the width of the first metal post 300 on the surface of the solder resist layer 200, C is the width of the upper surface of the first metal post 300, and D is the lower side of the first metal post 300 The following formula can be established for the width of the surface, and is true even if the width is replaced by the area.

C>B>D,A>D

The relationship between A and C is not limited, so A=C, A<C or A>C.

Even if the thicknesses of the electroless plating layer 310 are included in the above B, C, and D, the formula is the same.

The second metal pillar 400 is formed on the first metal pillar 300, and the electroless plating layer 310 formed on the side surface of the first metal pillar 300 extends to the side surface of the second metal pillar 400. However, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover at least a portion of the side surface of the second metal pillar 400. That is, as shown in FIG. 3, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover only a portion of the side surface of the second metal pillar 400. In this case, a portion of the second metal pillar 400 is over the electroless plating layer 310 such that the second metal pillar 400 protrudes beyond the electroless plating layer 310. Here, the second metal post 400 has a mushroom shape.

Alternatively, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover the entire side surface of the second metal pillar 400. In this case, the second metal post 400 may not protrude beyond the electroless plating layer 310 formed on the side surface of the metal post 300.

Figure 4 shows a printed circuit board in accordance with a third embodiment of the present invention.

Referring to FIG. 4, in the printed circuit board according to the third embodiment, the cross-sectional area of the first metal pillar 300 is increased from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300. The width of the first metal post 300 also increases from the upper surface of the first metal post 300 to the lower surface of the first metal post 300. The cross section of the first metal pillar 300 may be a trapezoidal pillar. In this case, the bonding area between the first metal post 300 and the metal pad 110 is increased to enable stable bonding.

When A is the width of the metal pad 110, B is the width of the first metal post 300 on the surface of the solder resist layer 200, C is the width of the upper surface of the first metal post 300, and D is the lower side of the first metal post 300 The following formula can be established for the width of the surface, and is true even if the width is replaced by the area.

A>D>B>C

Even if the thicknesses of the electroless plating layer 310 are included in the above B, C, and D, the formula is the same.

A≥D>B>C

The second metal pillar 400 is formed on the first metal pillar 300, and the electroless plating layer 310 formed on the side surface of the first metal pillar 300 extends to the side surface of the second metal pillar 400. However, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover at least a portion of the side surface of the second metal pillar 400. That is, as shown in FIG. 4, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover only a portion of the side surface of the second metal pillar 400. In this case, a portion of the second metal pillar 400 is over the electroless plating layer 310 such that the second metal pillar 400 protrudes beyond the electroless plating layer 310. Here, the second metal post 400 has a mushroom shape.

Alternatively, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover the entire side surface of the second metal pillar 400. In this case, the second metal post 400 may not protrude beyond the electroless plating layer 310 formed on the side surface of the metal post 300.

Figure 5 shows a printed circuit board in accordance with a fourth embodiment of the present invention.

Referring to FIG. 5, in the printed circuit board according to the fourth embodiment, the cross-sectional area of the first metal pillar 300 is increased from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300 and then decreased. The width of the first metal post 300 also increases from the upper surface of the first metal post 300 to the lower surface of the first metal post 300 and then decreases. Here, on the surface of the solder resist layer 200, the increase and decrease in the cross-sectional area (width) of the first metal pillar 300 may vary. That is, the cross-sectional area (width) of the first metal pillar 300 increases from the upper surface of the first metal pillar 300 to the surface of the solder resist layer 200, and then from the surface of the solder resist layer 200 to the first metal pillar 300. The lower surface is reduced.

However, the change in the cross section (width) of the first metal pillar 300 from the increase to the decrease does not necessarily have to occur on the surface of the solder resist layer 200. The point of change (the point at which the increase/decrease in the cross-sectional area (width) of the first metal pillar 300 changes) may be higher or lower than the surface of the solder resist layer 200.

In this embodiment, the volume of the first metal post 300 can be ensured while implementing the precise spacing of the first metal posts 300.

When A is the width of the metal pad 110, B is the width of the first metal post 300 on the surface of the solder resist layer 200, C is the width of the upper surface of the first metal post 300, and D is the lower side of the first metal post 300 The following formula can be established for the width of the surface, and is true even if the width is replaced by the area.

B>C,B>D

The width of the first metal post 300 at the point of change may be equal to or greater than the width of the metal pad 110. That is, B>A.

The first metal post 300 can have a minimum of cross-sectional area on the upper surface. That is, B>D>C.

Even if B, C, and D include the thickness of the electroless plating layer 310, the above formula remains the same.

If there is a change point on the surface of the solder resist layer 200, B is the width of the first metal pillar on the surface of the solder resist layer 200.

The second metal pillar 400 is formed on the first metal pillar 300, and the electroless plating layer 310 formed on the side surface of the first metal pillar 300 extends to the side surface of the second metal pillar 400. However, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover at least a portion of the side surface of the second metal pillar 400. That is, as shown in FIG. 5, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover only a portion of the side surface of the second metal pillar 400. In this case, a portion of the second metal pillar 400 is over the electroless plating layer 310 such that the second metal pillar 400 protrudes beyond the electroless plating layer 310. Here, the second metal post 400 has a mushroom shape.

Alternatively, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover the entire side surface of the second metal pillar 400. In this case, the second metal post 400 may not protrude beyond the electroless plating layer 310 formed on the side surface of the metal post 300.

Figure 6 shows a printed circuit board in accordance with a fifth embodiment of the present invention.

Referring to FIG. 6, in the printed circuit board according to the fifth embodiment, the second metal post 400 is formed on the first metal post 300. The second metal pillar 400 is formed on the electroless plating layer 310 formed on the side surface of the first metal pillar 300. That is, unlike the other embodiments described above, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 does not cover the side surface of the second metal pillar 400.

6 shows that the cross-sectional area of the first metal pillar 300 is substantially constant from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300, but is not limited to such a shape. As described in the second to fourth embodiments, the cross section of the first metal post 300 may vary.

Figure 42 shows a printed circuit board in accordance with a sixth embodiment of the present invention.

Referring to FIG. 42, in the printed circuit board according to the sixth embodiment, the height of the solder resist layer 200 may not be constant. The height of the solder resist layer 200 in the region around the first metal pillar 300 may be greater than the height of the solder resist layer 200 in other regions. That is, the height of the solder resist layer 200 in the region where the solder resist layer 200 contacts the electroless plating layer 310 of the first metal pillar 300 may be greater than the average height of the solder resist layer 200. This is because the solder resist layer 200 located in the region around the first metal pillar 300 is in a desmearing process or a process for lowering the height of the solder resist layer 200 during the process of manufacturing the printed circuit board which will be described later. The descum process is relatively removed relatively, or the adhesion between the electroless plating layer 310 of the first metal pillar 300 and the solder resist layer 200 may be large. However, the invention is not limited to this.

The shape of the first metal post 300 and the position of the second metal post 400 are shown in Fig. 42 in the same manner as in the first embodiment. However, in this case, the shape of the first metal post 300 and the position of the second metal post 400 are not limited to the same as those of the first embodiment, but may be changed to the first to fifth embodiments and the like.

Hereinafter, a method of manufacturing the printed circuit boards according to the first to fifth embodiments will be explained.

7 to 13 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a first embodiment of the present invention.

Referring to Fig. 7, an outermost layer circuit 120' and a metal pad 110 are formed on the insulating layer 100, and a solder resist layer 200 is formed on the insulating layer 100 to cover the outermost layer circuit 120' and the metal pad 110. The solder resist layer 200 is provided with an opening portion 210. The solder resist layer 200 is photosensitive, and the opening portion 210 can be formed by an exposure process and a developing process of a photolithography process. When the solder resist layer 200 is of a negative type, the mask may be placed in a region where the opening portion 210 is to be formed, and only a region other than the region where the opening portion 210 is to be formed may be selectively exposed. The opening portion 210 is formed on the metal pad 110 and at least a portion of the metal pad 110 may be exposed through the opening portion 210.

Referring to Fig. 8, an electroless plating layer S is formed on the opening portion 210 and the solder resist layer 200. The electroless plating layer S may be formed to have a thickness of 2 μm or less by electroless plating. The electroless plating layer S may be formed of, for example, a single layer of copper or a double layer of, for example, titanium and copper, but is not limited to such a metal.

Referring to FIG. 9, a first metal pillar 300 is formed in the opening portion 210. The first metal pillar 300 is formed of a plating layer P with the electroless plating layer S as a lead-in line. The height of the first metal pillar 300 is lower than the height of the solder resist layer 200.

Referring to FIG. 10, a second metal pillar 400 is formed on the plating layer P of the first metal pillar 300. The second metal pillar 400 may also be formed by electroplating with the electroless plating layer S as a lead-in wire. The second metal pillar 400 may be formed not to exceed the height of the solder resist layer 200.

Referring to FIG. 11, the electroless plating layer S formed on the solder resist layer 200 is removed. The electroless plating layer S can be removed by etching. Here, the remaining electroless plating layer 310 covers the side surface of the second metal pillar 400.

Referring to FIG. 12, the height of the solder resist layer 200 is reduced. The solder resist layer 200 may be locally removed by, for example, decontamination or slag removal, so that the height of the solder resist layer 200 may be lowered. As the height of the solder resist layer 200 becomes lower, the electroless plating layer 310 of the first metal pillar 300 is exposed to the outside. Here, the height of the solder resist layer 200 to be removed can be adjusted by adjusting the power of the decontamination or slag removal.

Referring to FIG. 13, the upper surface of the second metal post 400 is bent upward, and a portion of the second metal post 400 flows in a horizontal direction onto the electroless plating layer 310 by a reflow process. Therefore, the electroless plating layer 310 covers a portion of the side surface of the second metal pillar 400, and a portion of the second metal pillar 400 is located on the electroless plating layer 310.

In this embodiment, the cross-sectional area (width) of the opening portion 210 of the solder resist layer is substantially constant from the upper surface to the lower surface. The cross-sectional area (width) of the first metal post 300 is also substantially constant from the upper surface to the lower surface.

14 to 20 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a second embodiment of the present invention.

Referring to Fig. 14, an outermost layer circuit 120' and a metal pad 110 are formed on the insulating layer 100, and a solder resist layer 200 is formed on the insulating layer 100 to cover the outermost layer circuit 120' and the metal pad 110. The solder resist layer 200 is provided with an opening portion 210. The solder resist layer 200 is photosensitive, and the opening portion 210 can be formed by an exposure process and a developing process of the lithography process. When the solder resist layer 200 is of a negative type, the mask may be placed in a region where the opening portion 210 is to be formed, and only a region other than the region where the opening portion 210 is to be formed may be selectively exposed. The opening portion 210 is formed on the metal pad 110 and at least a portion of the metal pad 110 may be exposed through the opening portion 210.

The cross-sectional area and width of the opening portion 210 are reduced from the upper surface to the lower surface. Such a shape of the opening portion 210 can be applied by adjusting the wavelength of light for exposure. For example, the wavelength of light used for exposure may result in poor absorption at the machined surface. In particular, commonly used light can be composed of an I-line having a high absorption rate on the machined surface to effectively cause a photoreaction on the machined surface, and causing less on the machined surface. The light response of the H-line (H-line). In this embodiment, the dominant wavelength of light used for exposure may include an H line.

Referring to Fig. 15, an electroless plating layer S is formed on the opening portion 210 and the solder resist layer 200. The electroless plating layer S may be formed to have a thickness of 2 μm or less by electroless plating. The electroless plating layer S may be formed, for example, as a single layer of copper or as a double layer of, for example, titanium and copper.

Referring to FIG. 16, a first metal post 300 is formed in the opening portion 210. The first metal pillar 300 is formed of a plating layer P with the electroless plating layer S as a lead-in line. The height of the first metal pillar 300 is lower than the height of the solder resist layer 200.

Referring to FIG. 17, a second metal pillar 400 is formed on the plating layer P of the first metal pillar 300. The second metal pillar 400 may also be formed by electroplating with the electroless plating layer S as a lead-in wire. The second metal pillar 400 may be formed not to exceed the height of the solder resist layer 200.

Referring to FIG. 18, the electroless plating layer S formed on the solder resist layer 200 is removed. The electroless plating layer S can be removed by etching. Here, the remaining electroless plating layer 310 covers the side surface of the second metal pillar 400.

Referring to FIG. 19, the height of the solder resist layer 200 is reduced. The solder resist layer 200 may be locally removed by, for example, decontamination or slag removal, so that the height of the solder resist layer 200 may be lowered. As the height of the solder resist layer 200 becomes lower, the electroless plating layer 310 of the first metal pillar 300 is exposed to the outside.

Referring to FIG. 20, the upper surface of the second metal post 400 is bent upward, and a portion of the second metal post 400 flows in a horizontal direction onto the electroless plating layer 310 by a reflow process. Therefore, the electroless plating layer 310 covers a portion of the side surface of the second metal pillar 400, and a portion of the second metal pillar 400 is located on the electroless plating layer 310.

In this embodiment, the cross-sectional area (width) of the opening portion 210 of the solder resist layer is reduced from the upper surface to the lower surface, and the cross-sectional area (width) of the first metal pillar 300 is also reduced from the upper surface to the lower surface. small.

21 to 27 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a third embodiment of the present invention.

Referring to Fig. 21, an outermost layer circuit 120' and a metal pad 110 are formed on the insulating layer 100, and a solder resist layer 200 is formed on the insulating layer 100 to cover the outermost layer circuit 120' and the metal pad 110. The solder resist layer 200 is provided with an opening portion 210. The solder resist layer 200 is negatively photosensitive, and the opening portion 210 can be formed by an exposure process and a developing process of a lithography process. The opening portion 210 is formed on the metal pad 110 and at least a portion of the metal pad 110 may be exposed through the opening portion 210.

The cross-sectional area and width of the opening portion 210 are reduced from the upper surface to the lower surface. Such a shape of the opening portion 210 can be applied by adjusting the wavelength of light for exposure. For example, the wavelength of light used for exposure can be such that absorption at the machined surface is optimal. In particular, commonly used light can be composed of an I-line having a high absorption rate on a machined surface to effectively cause a photoreaction on the machined surface, and an H that causes less photoreaction on the machined surface. line. In this embodiment, the dominant wavelength of light used for exposure may include an I line.

Referring to Fig. 22, an electroless plating layer S is formed on the opening portion 210 and the solder resist layer 200. The electroless plating layer S may be formed to have a thickness of 2 μm or less by electroless plating. The electroless plating layer S may be formed, for example, as a single layer of copper or as a double layer of, for example, titanium and copper.

Referring to FIG. 23, a first metal post 300 is formed in the opening portion 210. The first metal pillar 300 is formed of a plating layer P with the electroless plating layer S as a lead-in line. The height of the first metal pillar 300 is lower than the height of the solder resist layer 200.

Referring to FIG. 24, a second metal pillar 400 is formed on the plating layer P of the first metal pillar 300. The second metal pillar 400 may also be formed by electroplating with the electroless plating layer S as a lead-in wire. The second metal pillar 400 may be formed not to exceed the height of the solder resist layer 200.

Referring to FIG. 25, the electroless plating layer S formed on the solder resist layer 200 is removed. The electroless plating layer S can be removed by etching. Here, the remaining electroless plating layer 310 covers the side surface of the second metal pillar 400.

Referring to FIG. 26, the height of the solder resist layer 200 is reduced. The solder resist layer 200 may be locally removed by, for example, decontamination or slag removal, so that the height of the solder resist layer 200 may be lowered. As the height of the solder resist layer 200 becomes lower, the electroless plating layer 310 of the first metal pillar 300 is exposed to the outside.

Referring to FIG. 27, the upper surface of the second metal post 400 is bent upward, and a portion of the second metal post 400 flows in a horizontal direction onto the electroless plating layer 310 by a reflow process. Therefore, the electroless plating layer 310 covers a portion of the side surface of the second metal pillar 400, and a portion of the second metal pillar 400 is located on the electroless plating layer 310.

In this embodiment, the cross-sectional area (width) of the opening portion 210 of the solder resist layer is increased from the upper surface to the lower surface, and the cross-sectional area (width) of the first metal pillar 300 is also increased from the upper surface to the lower surface. Big.

28 to 34 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a fourth embodiment of the present invention.

Referring to Fig. 28, an outermost layer circuit 120' and a metal pad 110 are formed on the insulating layer 100, and a solder resist layer 200 is formed on the insulating layer 100 to cover the outermost layer circuit 120' and the metal pad 110. The solder resist layer 200 is provided with an opening portion 210. The solder resist layer 200 is negatively photosensitive, and the opening portion 210 can be formed by an exposure process and a developing process of a lithography process. The opening portion 210 is formed on the metal pad 110 and at least a portion of the metal pad 110 may be exposed through the opening portion 210.

The cross-sectional area and width of the opening portion 210 increase from the upper surface to the lower surface and then decrease. Such a shape of the opening portion 210 can be applied by adjusting the wavelength of light for exposure.

For example, light having a wavelength that changes light at a particular point or that causes less photoreaction at the midpoint of the solder mask 200 can be used. Alternatively, light having a wavelength that mixes the I line that effectively causes a photoreaction on the machined surface with the H line that causes a small photoreaction on the machined surface at a ratio of 1:1 can be used.

Alternatively, the shape of the opening portion 210 may be applied using two solder resist layers 200 having different light absorptivity depending on the wavelength.

Referring to Fig. 29, an electroless plating layer S is formed on the opening portion 210 and the solder resist layer 200. The electroless plating layer S may be formed to have a thickness of 2 μm or less by electroless plating. The electroless plating layer S may be formed, for example, as a single layer of copper or as a double layer of, for example, titanium and copper.

Referring to FIG. 30, a first metal pillar 300 is formed in the opening portion 210. The first metal pillar 300 is formed of a plating layer P with the electroless plating layer S as a lead-in line. The height of the first metal pillar 300 is lower than the height of the solder resist layer 200.

Referring to FIG. 31, a second metal pillar 400 is formed on the plating layer P of the first metal pillar 300. The second metal pillar 400 may also be formed by electroplating with the electroless plating layer S as a lead-in wire. The second metal pillar 400 may be formed not to exceed the height of the solder resist layer 200.

Referring to FIG. 32, the electroless plating layer S formed on the solder resist layer 200 is removed. The electroless plating layer S can be removed by etching. Here, the remaining electroless plating layer 310 covers the side surface of the second metal pillar 400.

Referring to FIG. 33, the height of the solder resist layer 200 is reduced. The solder resist layer 200 may be locally removed by, for example, decontamination or slag removal, so that the height of the solder resist layer 200 may be lowered. As the height of the solder resist layer 200 becomes lower, the electroless plating layer 310 of the first metal pillar 300 is exposed to the outside.

The height of the solder resist layer 200 subjected to the decontamination or slag removal treatment may be lowered to the point (change point) at which the cross-sectional area of the first metal pillar 300 is the largest, but is not limited thereto. The height of the final solder resist layer 200 may be higher or lower than the point at which the cross-sectional area of the first metal pillar 300 is the largest.

Referring to FIG. 34, the upper surface of the second metal post 400 is bent upward, and a portion of the second metal post 400 flows in a horizontal direction onto the electroless plating layer 310 by a reflow process. Therefore, the electroless plating layer 310 covers a portion of the side surface of the second metal pillar 400, and a portion of the second metal pillar 400 is located on the electroless plating layer 310.

In this embodiment, the cross-sectional area (width) of the opening portion 210 of the solder resist layer is increased from the upper surface to the lower surface and then decreased, and the cross-sectional area (width) of the first metal pillar 300 is also from the upper surface. The lower surface increases and then decreases.

35 to 41 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a fifth embodiment of the present invention.

Referring to Fig. 35, an outermost layer circuit 120' and a metal pad 110 are formed on the insulating layer 100, and a solder resist layer 200 is formed on the insulating layer 100 to cover the outermost layer circuit 120' and the metal pad 110. The solder resist layer 200 is provided with an opening portion 210. The solder resist layer 200 is negatively photosensitive, and the opening portion 210 can be formed by an exposure process and a developing process of a lithography process. The opening portion 210 is formed on the metal pad 110 and at least a portion of the metal pad 110 may be exposed through the opening portion 210.

In Fig. 35, the cross-sectional area and width of the opening portion 210 are shown to be constant from the upper surface to the lower surface. However, the shape of the opening portion 210 is not limited thereto, and the shape of the opening portion 210 may be replaced with the shape described in the second to fourth embodiments.

Referring to Fig. 36, an electroless plating layer S is formed on the opening portion 210 and the solder resist layer 200. The electroless plating layer S may be formed to have a thickness of 2 μm or less by electroless plating. The electroless plating layer S may be formed, for example, as a single layer of copper or as a double layer of, for example, titanium and copper.

Referring to FIG. 37, a first metal post 300 is formed in the opening portion 210. The first metal pillar 300 is formed of a plating layer P with the electroless plating layer S as a lead-in line. The height of the first metal pillar 300 is equal to or higher than the height of the solder resist layer 200.

Referring to FIG. 38, a second metal pillar 400 is formed on the plating layer P of the first metal pillar 300. The second metal pillar 400 may also be formed by electroplating with the electroless plating layer S as a lead-in wire. The second metal pillar 400 may be formed to be higher than the height of the solder resist layer 200.

Referring to FIG. 39, the electroless plating layer S formed on the solder resist layer 200 is removed. The electroless plating layer S can be removed by etching.

Referring to FIG. 40, the height of the solder resist layer 200 is reduced. The solder resist layer 200 may be locally removed by, for example, decontamination or slag removal, so that the height of the solder resist layer 200 may be lowered. As the height of the solder resist layer 200 becomes lower, the electroless plating layer 310 of the first metal pillar 300 is exposed to the outside. The side surface of the second metal post 400 is also exposed to the outside.

Referring to FIG. 41, the upper surface of the second metal post 400 is bent upward, and the second metal post 400 flows in a horizontal direction onto the electroless plating layer 310 by a reflow process.

In this embodiment, the electroless plating layer 310 does not cover the side surface of the second metal pillar 400, and the entire second metal pillar 400 is formed to protrude beyond the electroless plating layer 310.

Although the present invention includes specific examples, it will be apparent to those skilled in the art that various forms can be made in the examples without departing from the spirit and scope of the scope of the claims. And changes in the details. The examples described herein are to be considered as illustrative only and not as limiting. Descriptions of features or aspects in each instance should be considered as suitable features or aspects in other examples. If the techniques are performed in a different order and/or if components in the system, architecture, apparatus, or circuitry are combined and/or replaced or supplemented with other components or equivalent components thereof, Achieve a suitable result. Therefore, the scope of the invention is not to be limited by the details of the invention, but the scope of the claims and the equivalents thereof in.

100, 100', 100''‧‧‧ insulation

110‧‧‧Metal pad

120, 120’‧‧‧ circuits

130‧‧‧through hole

200, 200'‧‧‧ solder mask

210‧‧‧ openings

300‧‧‧First metal column

310‧‧‧Electroless plating

400‧‧‧second metal column

500‧‧‧ solder balls

Figure 1 shows a printed circuit board in accordance with an embodiment of the present invention. Figure 2 shows a printed circuit board in accordance with a first embodiment of the present invention. Figure 3 shows a printed circuit board in accordance with a second embodiment of the present invention. Figure 4 shows a printed circuit board in accordance with a third embodiment of the present invention. Figure 5 shows a printed circuit board in accordance with a fourth embodiment of the present invention. Figure 6 shows a printed circuit board in accordance with a fifth embodiment of the present invention. 7 to 13 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a first embodiment of the present invention. 14 to 20 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a second embodiment of the present invention. 21 to 27 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a third embodiment of the present invention. 28 to 34 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a fourth embodiment of the present invention. 35 to 41 are cross-sectional views showing respective processes used in a method of manufacturing a printed circuit board according to a fifth embodiment of the present invention. Figure 42 shows a printed circuit board in accordance with a sixth embodiment of the present invention. Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The figures may not be drawn to scale, and the relative size, proportions, and depictions of the elements in the drawings may be exaggerated for clarity, illustration, and convenience.

Claims (17)

A printed circuit board comprising: a metal pad formed on an insulating layer; a solder resist layer having an opening for exposing at least a portion of the metal pad, and formed on the insulating layer; and a first metal pillar Formed on the metal pad in the opening portion and having an upper surface protruding above a surface of the solder resist layer, wherein an electroless plating is formed on the entire side surface and the lower surface of the first metal pillar Floor. The printed circuit board of claim 1, further comprising a second metal post formed on the first metal post, wherein a melting point of a metal forming the second metal post is lower than forming the first The melting point of the metal of the metal column. The printed circuit board of claim 2, wherein the electroless plating layer extends to at least a portion of a side surface of the second metal post. The printed circuit board of claim 2, wherein a portion of the second metal post is formed on the electroless plating layer. The printed circuit board of claim 1, wherein the solder resist layer contacts the electroless plating layer formed on the side surface of the first metal pillar. The printed circuit board of claim 1, wherein a width of the lower surface of the first metal post is less than a width of the metal pad. The printed circuit board of claim 6, wherein a cross-sectional area of the first metal post is reduced from the upper surface of the first metal post to the lower surface of the first metal post small. The printed circuit board of claim 7, wherein an area of the upper surface of the first metal post is equal to or larger than a cross-sectional area of the metal pad. The printed circuit board of claim 6, wherein a cross-sectional area of the first metal post increases from the upper surface of the first metal post to the lower surface of the first metal post Big. The printed circuit board of claim 6, wherein a cross-sectional area of the first metal post increases from the upper surface of the first metal post to the lower surface of the first metal post Large and then reduced. The printed circuit board of claim 10, wherein a cross-sectional area of the first metal post increases from the upper surface of the first metal post to the surface of the solder resist layer and The surface from the solder resist layer to the lower surface of the first metal pillar is reduced. The printed circuit board of claim 10, wherein a width of the first metal post on the surface of the solder resist layer is equal to or greater than a width of the metal pad. The printed circuit board of claim 10, wherein the first metal post has a minimum of the cross-sectional area on the upper surface. The printed circuit board of claim 6, wherein a cross-sectional area of the first metal post is constant from the upper surface of the first metal post to the lower surface of the first metal post constant. The printed circuit board of claim 2, wherein the upper surface of the second metal post comprises a convex curved surface. The printed circuit board of claim 1, wherein a slope of the side surface of the first metal post relative to the surface of the solder resist layer is greater than zero. The printed circuit board of claim 1, wherein a height of the solder resist layer in the surrounding area of the first metal pillar is greater than a height of the solder resist layer in other regions.