TWI812628B - 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

printed circuit board

The following instructions are for a printed circuit board.

Recently, bumps for mounting chips on printed circuit boards have been formed at precise pitches. Technologies for forming bumps include blue stencil printing (BSP) or u-ball technology, but due to technical limitations in these technologies, the formation of bump pitches is limited. To reduce bump pitch, a different approach than traditional methods is required. Therefore, attempts have been made to form bumps into shapes including metal columns.

[Related Technology]

South Korea 10-2013-0135214(2013.12.10)

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

According to an aspect of the present invention, a printed circuit board is provided. The printed circuit board includes: a metal pad formed on an insulating layer; a solder resist layer for exposing an opening of at least a portion of the metal pad formed on the insulating layer; and a first metal pillar formed on the metal pad in the opening and having a surface protruding from the solder resist layer The upper surface of the upper part has an electroless plating layer formed on the entire side surface and lower surface of the first metal pillar.

100, 100”: Insulation layer

100’:Core

110:Metal pad

120:Circuit

120’: Outermost circuit

130:Through hole

200, 200’: solder mask

210: opening

300:The first metal pillar

310. S: electroless plating layer

400: Second metal pillar

500: Solder ball

A, B, C, D: Width

P: electroplated layer

Figure 1 shows a printed circuit board according to an embodiment of the invention.

Figure 2 shows a printed circuit board according to a first embodiment of the invention.

Figure 3 shows a printed circuit board according to a second embodiment of the invention.

Figure 4 shows a printed circuit board according to a third embodiment of the invention.

Figure 5 shows a printed circuit board according to a fourth embodiment of the invention.

Figure 6 shows a printed circuit board according to a fifth embodiment of the invention.

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

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

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

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

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

Figure 42 shows a printed circuit board according to a sixth embodiment of the present invention.

Throughout the drawings and detailed description, the same reference numbers refer to the same elements. The drawings may not be drawn to scale, and the relative sizes, proportions, and illustrations of elements in the drawings may be exaggerated for clarity, illustration, and convenience.

The following detailed description is provided to assist the reader in obtaining a comprehensive understanding of the methods, apparatus, and/or systems described herein. However, various modifications, modifications, and equivalents of the methods, apparatus, and/or systems described herein will be apparent to those of ordinary skill in the art. The sequences of operations described herein are examples only, and are not limited to those mentioned herein, but as will be apparent to one of ordinary skill in the art, except for operations that necessarily occur in a specific order. Other than that, it can be changed. In addition, descriptions of functions and constructions that are well known to those of ordinary skill in the art may be omitted to enhance clarity and clarity.

Features described herein may be implemented in different forms and should not be construed as limited to the examples set forth herein. Rather, the examples described herein are provided so that this disclosure will be thorough and complete, and will convey the full scope of the invention to those skilled in the art.

Unless otherwise defined, all terms used in this article (including technical The meanings of technical terms and scientific terms) are the same as those commonly understood by those with ordinary knowledge in the art to which this invention belongs. Any term defined in a commonly used dictionary shall be construed to have the same meaning as in the context of the relevant technology and shall not be construed to have an idealized or overly formal meaning unless otherwise expressly defined.

Regardless of the figure number, the same or corresponding components will be given the same reference numbers and will not be described again. Throughout the description of the present invention, when specific related conventional techniques are described that are determined to be irrelevant to the viewpoint of the present invention, the relevant detailed description will be omitted. Terms such as "first" and "second" may be used when describing various components, but the above components should not be limited to the above terms. The above terms are only used to distinguish between the various components. In the drawings, some components may be exaggerated, omitted, or simplified, and the sizes of components do not necessarily reflect the actual sizes of the components.

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

Figure 1 shows a printed circuit board according to an embodiment of the 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 may further include second metal pillars 400 .

Printed circuit boards can be formed in multiple layers. The printed circuit board may be formed by a build-up layer including a core 100' located at the center of the printed circuit board and insulating layers 100 and 100" formed above and below the core 100'. The first metal pillar 300 and the second metal pillar 400 is formed laminated on the core 100' On the insulating layer 100 above, components such as chips are mounted on the first metal pillar 300 and the second metal pillar 400 . Additives such as solder balls 500 are formed under the insulating layer 100" laminated below the core 100' and the printed circuit board and motherboard are bonded together.

The printed circuit board may be a coreless substrate without a core. Furthermore, in this case, metal pillars are formed on the insulating layer located on the uppermost layer of the printed circuit board to mount the chip, and solder balls are formed on the insulating layer located on the lowermost layer of the printed circuit board to bond to motherboard.

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

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

The insulating layer 100 may be formed in multiple layers. A circuit 120 is formed in each insulating layer 100 . Circuit 120 is a conductor patterned to transmit electrical signals. The circuit 120 may be electrically connected via the via 130 . An outermost circuit 120' is formed on the uppermost insulating layer 100, and the outermost circuit 120' is electrically connected to another circuit 120 through a through hole 130. The location of the outermost circuit 120' is not limited, and a part of the outermost circuit 120' may be located between a plurality of first metal pillars 300 to be described later.

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

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

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

The solder resist layer 200 may be a photosensitive material containing inorganic fillers such as silicon dioxide. Resin, and the photosensitive resin may be epoxy resin. However, the materials are not limited to these materials, and any of commonly used materials used in printed circuit boards may be used.

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

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

The first metal pillar 300 is a pillar-shaped metal formed on the metal pad 110 in the opening 210 of the solder resist layer 200 . The first metal pillar 300 is used to install components, and can 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 relative 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 with respect to the surface of the solder resist 200 becomes zero (a section parallel to the surface of the solder resist 200 ).

An electroless plating layer 310 is formed on the entire side surface and 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 is connected to Contact 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 .

The 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 an electroplating layer with 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 metal including the same metal as the first metal pillar 300 in two layers. 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 may be formed to have a thickness of 2 micrometers (μm) or less.

A second metal pillar 400 may be formed on the first metal pillar 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 pillar 400 is used to combine the first metal pillar 300 with the component. The second metal pillar 400 is formed of a metal with a relatively lower melting point than the first metal pillar 300 , so that the second metal pillar 400 melts before the first metal pillar 300 melts during the reflow process.

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

In the following, the first to fifth embodiments will be explained according to the shape of the first metal pillar 300 and the position of the second metal pillar 400 . The insulating layer 100 on the uppermost layer of the printed circuit board is shown in FIGS. 2 to 41 , and layers formed below the insulating layer 100 are omitted.

Figure 2 shows a printed circuit board according to a first embodiment of the invention.

Referring to FIG. 2 , in the printed circuit board according to the first embodiment, the cross-sectional area (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 pillar 300 is also substantially constant from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300 . Here, "substantially constant" means that the width is constant including tolerance. The first metal pillar 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 pillar 300 on the surface of the solder resist layer 200 , C is the width of the upper surface of the first metal pillar 300 , and D is the lower surface of the first metal pillar 300 The following formula holds for the width of a surface, and holds true even when width is replaced by area.

A>B=C=D

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

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 part 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 located above the electroless plating layer 310 so that the second metal pillar 400 protrudes beyond the electroless plating layer 310 . Here, the second metal pillar 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 pillar 400 may not protrude beyond the electroless plating layer 310 formed on the side surface of the metal pillar 300 .

Figure 3 shows a printed circuit board according to a second embodiment of the 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 pillar 300 also becomes smaller from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300 . The cross section of the first metal pillar 300 may be an inverted trapezoidal pillar. In this case, the component mounting area is widened so that stable component mounting can be achieved.

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

C>B>D，A>D

There is no restriction on the relationship between A and C, so A=C, A<C or A>C.

Even if the thickness of the electroless plating layer 310 is included in B, C, and D above, the formula remains 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 part 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 part of the side surface of the second metal pillar 400 . In this case, a portion of the second metal pillar 400 is located above the electroless plating layer 310 so that the second metal pillar 400 protrudes beyond the electroless plating layer 310 . Here, the second metal pillar 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 pillar 400 may not protrude beyond the electroless plating layer 310 formed on the side surface of the metal pillar 300 .

Figure 4 shows a printed circuit board according to a third embodiment of the 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 increases 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 pillar 300 also increases from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 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 pillar 300 and the metal pad 110 is increased so that a stable bonding can be achieved.

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

A>D>B>C

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

D>B>C 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 second metal pillar 400 side surface. However, the electroless plating layer 310 formed on the side surface of the first metal pillar 300 may cover at least a part 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 located above the electroless plating layer 310 so that the second metal pillar 400 protrudes beyond the electroless plating layer 310 . Here, the second metal pillar 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 pillar 400 may not protrude beyond the electroless plating layer 310 formed on the side surface of the metal pillar 300 .

Figure 5 shows a printed circuit board according to a fourth embodiment of the 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 increases from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300 and then decreases. The width of the first metal pillar 300 also increases from the upper surface of the first metal pillar 300 to the lower surface of the first metal pillar 300 and then decreases. Here, on the surface of the solder resist layer 200, the cross-sectional area (width) of the first metal pillar 300 may increase and decrease. 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 increases from the surface of the solder resist layer 200 to the surface of 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 increasing to decreasing does not necessarily occur on the surface of the solder resist layer 200 . change point(first metal The point at which the increase/decrease in cross-sectional area (width) of pillar 300 occurs) may be above or below the surface of solder mask 200 .

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

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

B>C，B>D

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

The first metal pillar 300 may have a minimum 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 part 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 Only a portion of the side surface of the second metal pillar 400 may be covered. In this case, a portion of the second metal pillar 400 is located above the electroless plating layer 310 so that the second metal pillar 400 protrudes beyond the electroless plating layer 310 . Here, the second metal pillar 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 pillar 400 may not protrude beyond the electroless plating layer 310 formed on the side surface of the metal pillar 300 .

Figure 6 shows a printed circuit board according to a fifth embodiment of the invention.

Referring to FIG. 6 , in the printed circuit board according to the fifth embodiment, the second metal pillar 400 is formed on the first metal pillar 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 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 .

FIG. 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 this shape. As described in the second to fourth embodiments, the cross section of the first metal pillar 300 may vary.

Figure 42 shows a printed circuit board according to 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 area around the first metal pillar 300 may be greater than the height of the solder resist layer 200 in other areas. That is, solder mask The height of layer 200 in a region where solder resist 200 contacts electroless plating layer 310 of first metal pillar 300 may be greater than the average height of solder resist 200 . This is because the solder resist layer 200 in the area around the first metal pillar 300 is desmeared or removed during the desmearing process for lowering the height of the solder resist layer 200 during the process of manufacturing a printed circuit board to be described later. Relatively little is removed in the descum process, or the adhesion force between the electroless plating layer 310 of the first metal pillar 300 and the solder resist layer 200 may be large. However, the present invention is not limited to this.

The shape of the first metal pillar 300 and the position of the second metal pillar 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 pillar 300 and the position of the second metal pillar 400 are not limited to the same as the first embodiment, but may be changed to the first to fifth embodiments and so on.

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

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

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

Referring to FIG. 8 , an electroless plating layer S is formed in the opening 210 and on the solder resist layer 200 . The electroless plating layer S may be formed to have a thickness of 2 microns or less by electroless plating. The electroless plating layer S may be formed as a single layer of copper or as a double layer of titanium and copper, but is not limited to such metals.

Referring to FIG. 9 , a first metal pillar 300 is formed in the opening 210 . The first metal pillar 300 is formed of the electroplating layer P using 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 can also be formed by electroplating using the electroless plating layer S as a lead-in line. 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 Figure 12, the height of the solder resist layer 200 is reduced. The solder resist layer 200 can be partially removed by methods such as decontamination or slag removal, so that the height of the solder resist layer 200 can be reduced. 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 decontamination or slag removal.

Referring to FIG. 13 , the upper surface of the second metal pillar 400 is bent upward, and a part of the second metal pillar 400 flows horizontally onto the electroless plating layer 310 through a reflow process. Therefore, the electroless plating layer 310 covers the side surface of the second metal pillar 400 A part of the surface, and a part 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 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 pillar 300 is also substantially constant from the upper surface to the lower surface.

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

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

The cross-sectional area and width of the opening 210 decrease from the upper surface to the lower surface. Such a shape of the opening 210 can be implemented by adjusting the wavelength of light used for exposure. For example, the wavelength of light used for exposure may result in poor absorption at the machined surface. Specifically, commonly used light can be composed of: an I-line that has a high absorption rate on the processing surface to effectively cause a photoreaction on the processing surface, and an I-line that causes less light reaction on the processing surface. H-line of photoreaction. In this embodiment, the dominant wavelength of light used for exposure may include H lines.

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

Referring to FIG. 16 , a first metal pillar 300 is formed in the opening 210 . The first metal pillar 300 is formed of the electroplating layer P using 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 can also be formed by electroplating using the electroless plating layer S as a lead-in line. 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 Figure 19, the height of the solder resist layer 200 is reduced. The solder resist layer 200 can be partially removed by methods such as decontamination or slag removal, so that the height of the solder resist layer 200 can be reduced. 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 pillar 400 is bent upward, and a part of the second metal pillar 400 flows horizontally onto the electroless plating layer 310 through 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 210 of the solder resist layer decreases from the upper surface to the lower surface, and the cross-sectional area (width) of the first metal pillar 300 It also decreases from the upper surface to the lower surface.

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

Referring to Figure 21, the outermost circuit 120' and the metal pad 110 are formed on the insulating layer 100, and the solder resist layer 200 is formed on the insulating layer 100 to cover the outermost circuit 120' and the metal pad 110. The solder resist layer 200 is provided with an opening 210 . The solder resist layer 200 is negative photosensitive, and the opening 210 can be formed through the exposure process and development process of the photolithography process. The opening 210 is formed on the metal pad 110 and at least a part of the metal pad 110 may be exposed through the opening 210 .

The cross-sectional area and width of the opening 210 decrease from the upper surface to the lower surface. Such a shape of the opening 210 can be implemented by adjusting the wavelength of light used for exposure. For example, the wavelength of light used for exposure can optimize absorption at the machined surface. Specifically, the commonly used light may be composed of: I line that has a high absorption rate on the processing surface to effectively cause a light reaction on the processing surface, and H line that causes less light reaction on the processing surface. String. In this embodiment, the dominant wavelength of light used for exposure may include the I line.

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

Referring to FIG. 23 , a first metal pillar 300 is formed in the opening 210 . The first metal pillar 300 is formed of the electroplating layer P using the electroless plating layer S as a lead-in line. first gold The height of the 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 can also be formed by electroplating using the electroless plating layer S as a lead-in line. 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 Figure 26, the height of the solder resist layer 200 is reduced. The solder resist layer 200 can be partially removed by methods such as decontamination or slag removal, so that the height of the solder resist layer 200 can be reduced. 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 pillar 400 is bent upward, and a part of the second metal pillar 400 flows horizontally onto the electroless plating layer 310 through 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 210 of the solder resist layer increases from the upper surface to the lower surface, and the cross-sectional area (width) of the first metal pillar 300 also increases from the upper surface to the lower surface. big.

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

Referring to Figure 28, an outermost 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 circuit 120' and metal pad 110. The solder resist layer 200 is provided with an opening 210 . The solder resist layer 200 is negative photosensitive, and the opening 210 can be formed through the exposure process and development process of the photolithography process. The opening 210 is formed on the metal pad 110 and at least a part of the metal pad 110 may be exposed through the opening 210 .

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

For example, light having a wavelength that changes the light at a specific point or causes less light reaction at a midpoint of the solder resist layer 200 may be used. Alternatively, light having a wavelength that mixes an I-line that effectively causes a photoreaction on the processing surface and an H-line that causes a smaller photoreaction on the processing surface in a ratio of 1:1 may be used.

As another option, two solder resist layers 200 with different light absorbances may be used to shape the opening 210 according to the wavelength.

Referring to FIG. 29 , an electroless plating layer S is formed in the opening 210 and on the solder resist layer 200 . The electroless plating layer S may be formed to have a thickness of 2 microns or less by electroless plating. The electroless plating layer S may be formed as a single layer of, for example, 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 210 . The first metal pillar 300 is formed of the electroplating layer P using 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 Figure 31, a second gold layer is formed on the electroplating layer P of the first metal pillar 300. The column is 400. The second metal pillar 400 can also be formed by electroplating using the electroless plating layer S as a lead-in line. 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 Figure 33, the height of the solder resist layer 200 is reduced. The solder resist layer 200 can be partially removed by methods such as decontamination or slag removal, so that the height of the solder resist layer 200 can be reduced. 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 that undergoes decontamination or slag removal treatment may be reduced to a point (change point) where the cross-sectional area of the first metal pillar 300 is the largest, but is not limited thereto. The height of the final solder mask layer 200 may be higher or lower than the point where the cross-sectional area of the first metal pillar 300 is the largest.

Referring to FIG. 34 , the upper surface of the second metal pillar 400 is bent upward, and a part of the second metal pillar 400 flows horizontally onto the electroless plating layer 310 through 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 210 of the solder resist increases from the upper surface to the lower surface and then decreases, and the cross-sectional area (width) of the first metal pillar 300 also increases from the upper surface to the lower surface. increases to the lower surface and then decreases.

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

Referring to Figure 35, the outermost circuit 120' and the metal pad 110 are formed on the insulating layer 100, and the solder resist layer 200 is formed on the insulating layer 100 to cover the outermost circuit 120' and the metal pad 110. The solder resist layer 200 is provided with an opening 210 . The solder resist layer 200 is negative photosensitive, and the opening 210 can be formed through the exposure process and development process of the photolithography process. The opening 210 is formed on the metal pad 110 and at least a part of the metal pad 110 may be exposed through the opening 210 .

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

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

Referring to FIG. 37 , a first metal pillar 300 is formed in the opening 210 . The first metal pillar 300 is formed of the electroplating layer P using 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 can also be formed by electroplating using the electroless plating layer S as a lead-in line. The second metal pillar 400 may be formed to a height higher than 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 Figure 40, the height of the solder resist layer 200 is reduced. The solder resist layer 200 can be partially removed by methods such as decontamination or slag removal, so that the height of the solder resist layer 200 can be reduced. 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 pillar 400 is also exposed to the outside.

Referring to FIG. 41 , the upper surface of the second metal pillar 400 is bent upward, and the second metal pillar 400 flows horizontally onto the electroless plating layer 310 through 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 this invention includes specific examples, it will be apparent to those of ordinary skill in the art that various forms may be made in these examples without departing from the spirit and scope of the claimed scope and its equivalents. and changes in details. The examples set forth herein should be considered illustrative only and not limiting. Descriptions of features or aspects in each instance should be deemed to apply to similar features or aspects in other instances. The techniques may be performed in a different order and/or if components in the systems, architectures, devices or circuits are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Achieve appropriate results. Therefore, the scope of the present invention is not defined by the detailed description, but by the patent application scope and its equivalent range, and all changes within the scope of the patent application scope and its equivalent range shall be deemed to be included in the present invention. middle.

100, 100”‧‧‧Insulation layer

100’‧‧‧Core

110‧‧‧Metal Pad

120‧‧‧Circuit

120’‧‧‧Outermost circuit

130‧‧‧through hole

200, 200’‧‧‧Solder mask

300‧‧‧First Metal Pillar

400‧‧‧Second Metal Pillar

500‧‧‧Solder balls

Claims (15)

A printed circuit board, including: a metal pad formed on an insulating layer; a solder resist layer having an opening for exposing at least part of the metal pad and formed on the insulating layer; a first metal pillar, formed on the metal pad in the opening and having an upper surface protruding above the surface of the solder resist layer; and a second metal pillar formed on the first metal pillar, wherein the third metal pillar An electroless plating layer is formed on the entire side surface and lower surface of a metal pillar, wherein the melting point of the metal forming the second metal pillar is lower than the melting point of the metal forming the first metal pillar, wherein the second metal pillar A part of is formed on the electroless plating layer. The printed circuit board according to claim 1, wherein the electroless plating layer extends to at least a portion of the side surface of the second metal pillar. The printed circuit board according to claim 1, wherein the solder resist contacts the electroless plating layer formed on the entire side surface of the first metal pillar. The printed circuit board according to claim 1, wherein the upper surface of the second metal pillar includes a convex curved surface. The printed circuit board as claimed in claim 1, wherein the slope of the entire side surface of the first metal pillar relative to the surface of the solder resist layer greater than zero. The printed circuit board according to claim 1, wherein the height of the solder resist layer in the surrounding area of the first metal pillar is greater than the height of the solder resist layer in other areas. A printed circuit board, including: a metal pad formed on an insulating layer; a solder resist layer having an opening for exposing at least part of the metal pad and formed on the insulating layer; and a first metal pillar , formed on the metal pad in the opening and having an upper surface protruding above the surface of the solder resist layer, wherein electroless plating is formed on the entire side surface and lower surface of the first metal pillar layer, wherein the width of the lower surface of the first metal pillar is less than the width of the metal pad. The printed circuit board as claimed in claim 7, wherein the cross-sectional area of the first metal pillar decreases from the upper surface of the first metal pillar to the lower surface of the first metal pillar. Small. The printed circuit board as claimed in claim 8, wherein the area of the upper surface of the first metal pillar is equal to or greater than the cross-sectional area of the metal pad. The printed circuit board as claimed in claim 7, wherein the cross-sectional area of the first metal pillar is from the upper surface of the first metal pillar to the third The lower surface of a metal post is enlarged. The printed circuit board as claimed in claim 7, wherein the cross-sectional area of the first metal pillar increases from the upper surface of the first metal pillar to the lower surface of the first metal pillar. Large and then decrease. The printed circuit board as claimed in claim 11, wherein the cross-sectional area of the first metal pillar increases from the upper surface of the first metal pillar to the surface of the solder resist layer. is large and decreases from the surface of the solder mask to the lower surface of the first metal pillar. The printed circuit board as claimed in claim 11, wherein the width of the first metal pillar on the surface of the solder resist layer is equal to or greater than the width of the metal pad. The printed circuit board as claimed in claim 11, wherein the first metal pillar has the minimum value of the cross-sectional area on the upper surface of the first metal pillar. The printed circuit board as claimed in claim 7, wherein the cross-sectional area of the first metal pillar is constant from the upper surface of the first metal pillar to the lower surface of the first metal pillar. unchanged.