JP2019080042A - Printed circuit board - Google Patents

Abstract

To provide a printed circuit board including a post excellent on alignment.SOLUTION: A printed circuit board includes: a metal pad 110 formed on an insulating layer 100; a solder resist layer 200 including an opening that exposes at least a part of the metal pad 110 and laminated on the insulating layer 100; and a first metal post 300 formed on the metal pad 110 in the opening, and having an upper surface projecting from the surface of the solder resist layer 200. An electroless plating layer is formed on the entire side and a lower surface of the first metal post 300.SELECTED DRAWING: Figure 1

Description

  The present invention relates to printed circuit boards.

  Recently, bumps for mounting a chip on a printed circuit board are formed at a fine pitch. There are BSP or U-ball (U-ball) technology as a method of forming a bump, but in this technology, the limit of the bump pitch is limited due to the technical limit. Therefore, in order to reduce the bump pitch, a method different from the conventional method is required. As a result, attempts have been made to form the bumps into a shape including a metal column.

Korean Published Patent No. 10-2013-0135214

  It is an object of the present invention to provide a printed circuit board comprising posts with good alignment.

  According to one aspect of the present invention, a metal pad formed on an insulating layer, an opening for exposing at least a part of the metal pad, and a solder resist layer laminated on the insulating layer, and the opening And a first metal post formed on the metal pad in the upper surface, the upper surface projecting on the surface of the solder resist layer, and the electroless plating layer is formed on the entire side surface and the lower surface of the first metal post. A printed circuit board is provided.

FIG. 2 is a view showing a printed circuit board according to an embodiment of the present invention. FIG. 1 is a view showing a printed circuit board according to a first embodiment of the present invention. It is a figure showing the printed circuit board concerning a 2nd example of the present invention. It is a figure showing a printed circuit board concerning a 3rd example of the present invention. It is a figure showing a printed circuit board concerning a 4th example of the present invention. It is a figure showing the printed circuit board concerning a 5th example of the present invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 1st Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 1st Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 1st Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 1st Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 1st Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 1st Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 1st Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 2nd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 2nd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 2nd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 2nd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 2nd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 2nd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 2nd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 4th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 4th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 4th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 4th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 4th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 4th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 4th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 5th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 5th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 5th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 5th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 5th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 5th Example of this invention. It is a figure for demonstrating the manufacturing method of the printed circuit board which concerns on 5th Example of this invention. It is a figure which shows the printed circuit board which concerns on 6th Example of this invention.

  The embodiments of the printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be denoted by the same reference numerals as in the description with reference to the accompanying drawings. Duplicate descriptions will be omitted.

  Further, the terms "first", "second" and the like used in the following are merely identification symbols for distinguishing identical or corresponding components, and identical or corresponding components are first, second, etc. It is not limited by the term of.

  In addition, “coupling” does not mean only when each component is in direct physical contact in the contact relationship between each component, and another configuration is interposed between each component, Other configurations are used as an inclusive concept until each component is in contact.

  FIG. 1 is a view showing a printed circuit board according to 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 post 300, and includes a second metal post 400. It can further include.

  The printed circuit board can be formed in multiple layers. Among the layers forming the printed circuit board, the core 100 ′ may be located at the center of the printed circuit board, and the insulating layers 100 and 100 ′ ′ may be buildup layers stacked above and below the core. Metal posts 300 and 400 are formed on the insulating layer 100 stacked on the top of the core 100 ′, and an element such as a chip is mounted on the metal posts 300 and 400. Under the insulating layer 100 ′ ′ stacked under the core 100 ′, a bonding agent such as a solder ball 500 is formed, and the printed circuit board and the main board are bonded.

  The printed circuit board may be a coreless coreless board. Also in this case, a metal post is formed on the insulating layer located on the uppermost layer of the printed circuit board to mount the chip, and a solder ball is formed on the insulating layer located on the lower layer of the printed circuit board to form the main board. It can be joined.

  The core 100 ′ and / or the insulating layer 100 is a material composed of an insulating material such as a resin, and has a thin plate shape. As resin of core 100 'and / or insulating layer 100, various materials, such as thermosetting resin and thermoplastic resin, can be used, and an epoxy resin, polyimide, etc. are specifically mentioned. Here, as the epoxy resin, for example, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, cresol novolac type epoxy resin, rubber modified epoxy resin, cycloaliphatic type epoxy Although a resin, a silicone type epoxy resin, a nitrogen type epoxy resin, a phosphorus type epoxy resin etc. are mentioned, it is not limited to these.

  The core 100 ′ and / or the insulating layer 100 may be a prepreg (Prepreg or PPG) in which a fiber reinforcing material such as glass cloth is included in the above-mentioned resin. The insulating layer 100 may be a build up film in which the resin is filled with an inorganic filler such as silica. Examples of this buildup film include ABF (Ajinomoto Build-up Film).

  The insulating layer 100 can be configured in plural. A circuit 120 is formed in each insulating layer 100. Circuit 120 is a conductor that is patterned to transmit electrical signals. The circuit 120 can be electrically connected through the via 130. In addition, the outermost layer circuit 120 ′ is formed on the insulating layer 100 located at the top, and is electrically connected to the other circuits 120 through the vias 130. The position of the outermost layer circuit 120 'is not limited, and a portion thereof may be positioned between a plurality of first metal posts 300 described later.

  The circuits 120 and 120 'are made of copper (Cu), palladium (Pd), aluminum (Al), nickel (Ni), titanium (Ti), gold (Au), platinum (Pt), etc. in consideration of the electrical conductivity. Or their alloys.

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

  The solder resist layer 200 is stacked on the insulating layer 100 and includes an opening 210 that exposes at least a portion of the metal pad 110. That is, the opening 210 of the solder resist layer 200 is formed on the metal pad 110, and the width of the region exposed from the opening 210 of the metal pad 110 can be smaller than the width of the metal pad 110. is there. In this case, the width of the lower surface of the first metal post 300 described later is smaller than the width of the metal pad 110.

  The solder resist layer 200 can be formed of a photosensitive resin containing an inorganic filler such as silica, and an epoxy resin can be used as the photosensitive resin. However, it is not limited to this material, and all common materials usable in printed circuit boards can be used.

  On the other hand, the solder resist layer 200 may be positive or negative. In the following description, the negative will be mainly described, but the positive is not excluded.

  In the printed circuit board, the solder resist layer 200 ′ is also laminated under the insulating layer 100 ′ ′ laminated under the core 100 ′.

  The first metal post 300 is a columnar metal formed on the metal pad 110 in the opening 210 of the solder resist layer 200. The first metal post 300 plays a role of mounting the device and may be formed in plurality.

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

  The first metal post 300 does not contact the surface (upper surface) of the solder resist layer 200.

  The inclination of the side surface of the first metal post 300 is greater than 0 ° with respect to the surface of the solder resist layer 200. That is, there is no section (section parallel to the surface of the solder resist layer 200) on the side surface of the first metal post 300 where the inclination with respect to the surface of the solder resist layer 200 is zero.

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

  The electroless plating layer 310 formed on the side surface of the first metal post 300 contacts the solder resist layer 200. Therefore, the width (area) of the opening 210 of the solder resist layer 200 on the surface of the solder resist layer 200 and the width (area) of the first metal post 300 including the electroless plating layer 310 are the same.

  Also, the electroless plating layer 310 formed on the lower surface of the first metal post 300 is formed on the upper surface of the metal pad 110. That is, the electroless plating layer 310 is interposed between the first metal post 300 and the metal pad 110. In this case, the first metal post 300 may be an electrolytic plating layer using the electroless plating layer 310 as a lead-in wire.

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

  The electroless plating layer 310 may be formed of the same metal as the first metal post 300. For example, the first metal post 300 and the electroless plating layer 310 may be all formed of copper (Cu). The electroless plating layer 310 does not necessarily have to be formed of the same metal as the first metal post 300 but can be formed in two layers. The electroless plating layer 310 may be formed in two layers including the same metal as the first metal post 300. For example, the first metal post 300 may be formed of copper (Cu), and the electroless plating layer 310 may be formed in a two-layer structure of a titanium (Ti) layer and a copper (Cu) layer. Here, although the titanium electroless plating layer 310 is formed as the outermost layer and can be exposed to the outside, it is not excluded that copper (Cu) is formed as the outermost layer.

  The electroless plating layer 310 may be formed by electroless plating and may have a thickness of 2 μm or less.

  The second metal post 400 is formed on the first metal post 300. The melting point of the metal forming the second metal post 400 is lower than the melting point of the metal forming the first metal post 300.

  For example, the first metal post 300 may be formed of copper, and the second metal post 400 may be formed of tin (Sn).

  The second metal post 400 plays a role of bonding the first metal post 300 and the element, and has a relatively low melting point so as to melt before the first metal post 300 in a reflow process. It is formed of metal.

  The second metal post 400 may be formed to a thickness smaller than the thickness of the first metal post 300 and may be formed by plating. Through the reflow process, the second metal post 400 may flow to the left and right, and the upper surface of the second metal post 400 may be curved upward.

  Hereinafter, the first to fifth embodiments will be described separately according to the shape of the first metal post 300 and the position of the second metal post 400. FIGS. 2 to 41 show the insulating layer 100 located at the top of the printed circuit board, and the layers formed thereunder are omitted.

  FIG. 2 is a view showing a printed circuit board according to the first embodiment of the present invention.

  Referring to FIG. 2, in the printed circuit board according to the first embodiment, the cross-sectional area of the first metal post 300 is substantially constant from the upper surface to the lower surface of the first metal post 300. The width of the first metal post 300 is also substantially constant from the top to the bottom of the first metal post 300. Here, "substantially constant" means constant including tolerance. The first metal post 300 may have a cylindrical or polygonal shape.

  Assuming that the width of the metal pad 110 is A, the width of the first metal post 300 on the surface of the solder resist layer B is B, the width of the upper surface of the first metal post 300 is C, and the width of the lower surface of the first metal post 300 is D The following inequality holds, and the above-mentioned "width" may be substituted for "area".

  A> B = C = D

  Further, when the thickness of the electroless plating layer 310 is included in the above-mentioned B, C, and D, the following inequality can be established.

  A B B = C = D

  Meanwhile, the second metal post 400 may be formed on the first metal post 300, and the electroless plating layer 310 formed on the side surface of the first metal post 300 may extend to the side surface of the second metal post 400. it can. However, the electroless plating layer 310 formed on the side surface of the first metal post 300 may cover at least a part of the side surface of the second metal post 400. That is, as shown in FIG. 2, the electroless plating layer 310 formed on the side surface of the first metal post 300 can cover only a part of the side surface of the second metal post 400. In this case, a portion of the second metal post 400 is located on the top of the electroless plating layer 310, and the second metal post 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 post 300 may cover the entire side surface of the second metal post 400, in which case, the second metal post 400 may be the first metal post 300. It does not protrude from the electroless plating layer 310 formed on the side surface of

  FIG. 3 is a view showing a printed circuit board according to 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 post 300 decreases from the upper surface to the lower surface of the first metal post 300. The width of the first metal post 300 also decreases from the upper surface to the lower surface of the first metal post 300. The first metal post 300 may be formed in a pillar shape having an inverted trapezoidal cross section. In this case, the mounting area of the element is increased, and the element can be stably mounted.

  Assuming that the width of the metal pad 110 is A, the width of the first metal post 300 on the surface of the solder resist layer B is B, the width of the upper surface of the first metal post 300 is C, and the width of the lower surface of the first metal post 300 is D The following inequality holds, and the above-mentioned "width" may be substituted for "area".

  C> B> D, A> D

  Since the relationship between A and C is not limited, it is possible that A = C, A <C, A> C.

  In addition, the above inequality sign is the same even when the thickness of the electroless plating layer 310 is included in the above B, C, and D.

  Meanwhile, the second metal post 400 is formed on the first metal post 300, and the electroless plating layer 310 formed on the side surface of the first metal post 300 extends on the side surface of the second metal post 400. Can. However, the electroless plating layer 310 formed on the side surface of the first metal post 300 may cover at least a part of the side surface of the second metal post 400. That is, as shown in FIG. 3, the electroless plating layer 310 formed on the side surface of the first metal post 300 can cover only a part of the side surface of the second metal post 400. In this case, a portion of the second metal post 400 is located on the top of the electroless plating layer 310, and the second metal post 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 post 300 may cover the entire side surface of the second metal post 400, in which case the second metal post 400 may be a portion of the first metal post 300. It does not protrude from the electroless plating layer 310 formed on the side surface.

  FIG. 4 is a view showing a printed circuit board according to 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 post 300 increases from the upper surface to the lower surface of the first metal post 300. The width of the first metal post 300 also increases from the upper surface to the lower surface of the first metal post 300. The first metal post 300 may be formed in a columnar shape having a (positive) trapezoidal cross section. In this case, the bonding area between the first metal post 300 and the metal pad 110 is increased, and stable bonding can be achieved.

  Assuming that the width of the metal pad 110 is A, the width of the first metal post 300 on the surface of the solder resist layer B is B, the width of the upper surface of the first metal post 300 is C, and the width of the lower surface of the first metal post 300 is D The following inequality holds, and the above-mentioned "width" may be substituted for "area".

  A> D> B> C

  Further, when the thickness of the electroless plating layer 310 is included in the above B, C, and D, the following inequality can be established.

  A ≧ D> B> C

  Meanwhile, the second metal post 400 is formed on the first metal post 300, and the electroless plating layer 310 formed on the side surface of the first metal post 300 extends on the side surface of the second metal post 400. Can. However, the electroless plating layer 310 formed on the side surface of the first metal post 300 may cover at least a part of the side surface of the second metal post 400. That is, as shown in FIG. 4, the electroless plating layer 310 formed on the side surface of the first metal post 300 can cover only a part of the side surface of the second metal post 400. In this case, a portion of the second metal post 400 is located on the top of the electroless plating layer 310, and the second metal post 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 post 300 can cover the entire side surface of the second metal post 400, in which case the second metal post 400 is the first metal. It does not protrude beyond the electroless plating layer 310 formed on the side surface of the post 300.

  FIG. 5 is a view showing a printed circuit board according to 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 post 300 becomes larger as it goes from the top surface of the first metal post 300 to the bottom surface. The width of the first metal post 300 also increases and decreases as it goes from the top surface to the bottom surface of the first metal post 300. Here, the increase or decrease of the cross-sectional area (width) of the first metal post 300 can be changed on the surface of the solder resist layer 200. That is, the cross sectional area (width) of the first metal post 300 increases from the top surface of the first metal post 300 to the surface of the solder resist layer 200, and the first metal post from the surface of the solder resist layer 200. It becomes smaller as it goes to the lower side of 300.

  However, the increase or decrease in the cross sectional area (width) of the first metal post 300 does not necessarily change on the surface of the solder resist layer 200, but the inflection point (the point where the increase or decrease in the cross sectional area (width) of the first metal post 300 changes) May be higher or lower than the surface of the solder resist layer 200.

  In the present embodiment, the volume of the first metal post 300 can be secured while realizing the fine pitch of the first metal post 300.

  Assuming that the width of the metal pad 110 is A, the width of the first metal post 300 at the inflection point is B, the width of the upper surface of the first metal post 300 is C, and the width of the lower surface of the first metal post 300 is D The same applies even if the above "width" is replaced with "area".

  B> C, B> D

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

  Also, the first metal post 300 may have a minimum value of the cross-sectional area at the top surface. That is, B> D> C can be achieved.

  The above inequalities are the same even if B, C, and D include the thickness of the electroless plating layer 310.

  When a point of inflection exists on the surface of the solder resist layer 200, B is the width of the first metal post on the surface of the solder resist layer 200.

  Meanwhile, the second metal post 400 may be formed on the first metal post 300, and the electroless plating layer 310 formed on the side surface of the first metal post 300 may extend to the side surface of the second metal post 400. it can. However, the electroless plating layer 310 formed on the side surface of the first metal post 300 may cover at least a part of the side surface of the second metal post 400. That is, as shown in FIG. 5, the electroless plating layer 310 formed on the side surface of the first metal post 300 can cover only a part of the side surface of the second metal post 400. In this case, a portion of the second metal post 400 is located on the top of the electroless plating layer 310, and the second metal post 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 post 300 may cover the entire side surface of the second metal post 400, in which case, the second metal post 400 may be the first metal post 300. It does not protrude beyond the electroless plating layer 310 formed on the side surface of

  FIG. 6 is a view showing a printed circuit board according to 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, and the second metal post 400 is formed on the side surface of the first metal post 300. It is located on the electroless plating layer 310. That is, unlike the other embodiments described above, the electroless plating layer 310 formed on the side surface of the first metal post 300 does not cover the side surface of the second metal post 400.

  However, although the cross-sectional area of the first metal post 300 is substantially constant from the upper surface to the lower surface of the first metal post 300 in FIG. 6, the present invention is not limited to this shape. The cross section of the first metal post 300 described above can be changed.

  FIG. 42 is a view showing 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 is not constant. The height of the solder resist layer 200 in the peripheral region of the first metal post 300 may be greater than the height of the solder resist layer 200 in the other regions. That is, the height of the solder resist layer 200 in a region where the solder resist layer 200 is in contact with the electroless plating layer 310 of the first metal post 300 may be larger than the average height of the solder resist layer 200. This is a result of relatively little removal of the solder resist layer 200 in the peripheral portion of the first metal post 300 in a desmear or descum process for reducing the height of the solder resist layer 200 in a printed circuit board manufacturing process described later. Or the adhesion between the electroless plating layer 310 of the first metal post 300 and the solder resist layer 200 may be large, but is not limited thereto.

  On the other hand, although the shape of the first metal post 300 and the position of the second metal post 400 are shown in FIG. 42 as in the first embodiment, the shape of the first metal post 300 and the second metal post of this embodiment are shown. The position 400 is not limited as in the first embodiment, but can be changed from the first embodiment to the fifth embodiment or the like.

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

  7 to 13 are views showing a method of manufacturing a printed circuit board according to the first embodiment of the present invention.

  Referring to FIG. 7, the outermost layer circuit 120 ′ and the metal pad 110 are formed on the insulating layer 100, and the solder resist layer 200 covering the outermost layer circuit 120 ′ and the metal pad 110 is stacked on the insulating layer 100. . Also, an opening 210 is formed in the solder resist layer 200. The solder resist layer 200 is photosensitive, and the openings 210 can be formed through the exposure and development processes of the photolithography process. When the solder resist layer 200 is negative, a mask can be positioned in the area where the opening 210 is to be formed, and only areas 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 portion of the metal pad 110 can be exposed through the opening 210.

  Referring to FIG. 8, an electroless plating layer S is formed on the inside of the opening 210 and on the solder resist layer 200. The electroless plating layer S can be formed to have a thickness of 2 μm or less by electroless plating, and can be formed on a single layer such as copper or a double layer such as titanium and copper. Not limited to

  Referring to FIG. 9, an electrolytic plating layer P for forming the first metal post 300 in the opening 210 is formed. That is, the first metal post 300 is formed of an electrolytic plating layer P using the electroless plating layer S as a lead-in wire. The height of the first metal post 300 may be lower than the height of the solder resist layer 200.

  Referring to FIG. 10, a second metal post 400 is formed on the electrolytic plating layer P of the first metal post 300. The second metal post 400 can also be formed by electrolytic plating using the electroless plating layer S as a lead-in wire. The second metal post 400 can 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 S covers the side surface of the second metal post 400.

  Referring to FIG. 12, the height of the solder resist layer 200 is reduced. The solder resist layer 200 can be lowered in height by partially removing the solder resist layer 200 by a method such as desmear or descum. The reduced height of the solder resist layer 200 exposes the electroless plating layer 310 of the first metal post 300 to the outside. Here, the height of the removed solder resist layer 200 can be adjusted by adjusting the power of desmear or descum.

  Referring to FIG. 13, after the reflow process, the upper surface of the second metal post 400 bulges upward, and a portion of the second metal post 400 flows horizontally onto the electroless plating layer 310. become. As a result, the electroless plating layer 310 covers a portion of the side surface of the second metal post 400, and a portion of the second metal post 400 is located on the electroless plating layer 310.

  On the other hand, in the present embodiment, the cross-sectional area (width) of the opening 210 of the solder resist is substantially constant from the top to the bottom, and the cross-section (width) of the first metal post 300 is also substantially from the top to the bottom. It is constant.

  14 to 20 are views showing a method of manufacturing a printed circuit board according to a second embodiment of the present invention.

  Referring to FIG. 14, the outermost circuit 120 ′ and the metal pad 110 are formed on the insulating layer 100, and the solder resist layer 200 covering the outermost circuit 120 ′ and the metal pad 110 is stacked on the insulating layer 100. Also, an opening 210 is formed in the solder resist layer 200. The solder resist layer 200 is photosensitive, and the openings 210 can be formed by the exposure and development steps of the photolithography step. When the solder resist layer 200 is a negative type, the mask can be positioned in the area where the opening 210 is formed, and selective exposure can be performed only in the area other than the area where the opening 210 is formed. The opening 210 is formed on the metal pad 110, and at least a portion of the metal pad 110 can be exposed through the opening 210.

  The cross-sectional area and width of the opening 210 decrease from the top to the bottom. The shape of the opening 210 can be realized by adjusting the wavelength of light used for exposure. For example, the wavelength of light used for exposure may cause less absorption at the processing surface. Specifically, general light has high absorptivity on the processing surface, and I-line actively causes photoreaction on the processing surface, whereas H-line causes less photoreaction on the processing surface. The main wavelength of light used for exposure in this embodiment can be included in H-line.

  Referring to FIG. 15, an electroless plating layer S is formed on the inside of the opening 210 and on the solder resist layer 200. The electroless plating layer S can be formed to a thickness of 2 μm or less by electroless plating, and can be formed to a single layer such as copper or a double layer such as titanium and copper.

  Referring to FIG. 16, an electrolytic plating layer P for forming the first metal post 300 in the opening 210 is formed. That is, the first metal post 300 is formed of an electrolytic plating layer P using the electroless plating layer S as a lead-in wire. The height of the first metal post 300 may be lower than the height of the solder resist layer 200.

  Referring to FIG. 17, a second metal post 400 is formed on the electrolytic plated layer P of the first metal post 300. The second metal post 400 can also be formed by electrolytic plating using the electroless plating layer S as a lead-in wire. The second metal post 400 can 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 post 400.

  Referring to FIG. 19, the height of the solder resist layer 200 is reduced. The solder resist layer 200 can be lowered in height by being partially removed by a method such as desmear or descum. The reduced height of the solder resist layer 200 exposes the electroless plating layer 310 of the first metal post 300 to the outside.

  Referring to FIG. 20, after the reflow process, the upper surface of the second metal post 400 is curved upward, and a part of the second metal post 400 flows horizontally onto the electroless plating layer 310. As a result, the electroless plating layer 310 covers a portion of the side surface of the second metal post 400, and a portion of the second metal post 400 is located on the electroless plating layer 310.

  On the other hand, in the present embodiment, the cross-sectional area (width) of the opening 210 of the solder resist becomes smaller as it goes from the upper surface to the lower surface, and the cross-sectional area (width) of the first metal post 300 becomes smaller as it goes from the upper surface to the lower surface.

  21 to 27 are views showing a method of manufacturing a printed circuit board according to the third embodiment of the present invention.

  Referring to FIG. 21, the outermost circuit 120 ′ and the metal pad 110 are formed on the insulating layer 100, and the solder resist layer 200 covering the outermost circuit 120 ′ and the metal pad 110 is stacked on the insulating layer 100. Also, an opening 210 is formed in the solder resist layer 200. The solder resist layer 200 is negative photosensitive, and the opening 210 can be formed by the exposure and development steps of the photolithography step. The opening 210 is formed on the metal pad 110, and at least a portion of the metal pad 110 can be exposed through the opening 210.

  The cross-sectional area and width of the opening 210 increase from the top to the bottom. The shape of the opening 210 can be realized by adjusting the wavelength of light used for exposure. For example, the wavelength of light used for exposure may be the one with the largest absorption at the processing surface. Specifically, general light has high absorptivity on the processing surface, and I-line actively causes photoreaction on the processing surface, whereas H-line causes less photoreaction on the processing surface. And the main wavelength of light used for exposure in this embodiment can be included in I-line.

  Referring to FIG. 22, an electroless plating layer S is formed on the inside of the opening 210 and on the solder resist layer 200. The electroless plating layer S can be formed to a thickness of 2 μm or less by electroless plating, and can be formed of a single layer such as copper or a double layer such as titanium and copper.

  Referring to FIG. 23, an electrolytic plating layer P for forming the first metal post 300 in the opening 210 is formed. That is, the first metal post 300 is formed of an electrolytic plating layer P using the electroless plating layer S as a lead-in wire. The height of the first metal post 300 may be lower than the height of the solder resist layer 200.

  Referring to FIG. 24, a second metal post 400 is formed on the electrolytic plated layer P of the first metal post 300. The second metal post 400 can also be formed by electrolytic plating using the electroless plating layer S as a lead-in wire. The second metal post 400 can 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 post 400.

  Referring to FIG. 26, the height of the solder resist layer 200 is reduced. The height of the solder resist layer 200 can be lowered by partially removing the solder resist layer 200 by a method such as desmear or descum. The reduced height of the solder resist layer 200 exposes the electroless plating layer 310 of the first metal post 300 to the outside.

  Referring to FIG. 27, after the reflow process, the upper surface of the second metal post 400 is curved upward and a portion of the second metal post 400 flows horizontally onto the electroless plating layer 310. As a result, the electroless plating layer 310 covers a portion of the side surface of the second metal post 400, and a portion of the second metal post 400 is located on the electroless plating layer 310.

  On the other hand, in the present embodiment, the cross-sectional area (width) of the opening 210 of the solder resist increases from the upper surface to the lower surface, and the cross-sectional area (width) of the first metal post 300 also increases from the upper surface to the lower surface.

  FIGS. 28 to 34 are views showing a method of manufacturing a printed circuit board according to the fourth embodiment of the present invention.

  Referring to FIG. 28, the outermost circuit 120 ′ and the metal pad 110 are formed on the insulating layer 100, and the solder resist layer 200 covering the outermost circuit 120 ′ and the metal pad 110 is stacked on the insulating layer 100. Also, an opening 210 is formed in the solder resist layer 200. The solder resist layer 200 is negative photosensitive, and the opening 210 can be formed by the exposure and development steps of the photolithography step. The opening 210 is formed on the metal pad 110, and at least a portion of the metal pad 110 can be exposed through the opening 210.

  The openings 210 increase and decrease in cross-sectional area and width from the top to the bottom. The shape of the opening 210 can be realized by adjusting the wavelength of light used for exposure.

  For example, the wavelength of light may be changed at a specific point, or light of a wavelength that causes less light reaction at an intermediate point of the solder resist layer 200 may be used. Alternatively, use a mixture in which the wavelengths included in each of the I-line that causes photoreaction to be active on the processing surface and the H-line that causes less photoreaction on the processing surface are approximately 1: 1. Can.

  Alternatively, the shape of the opening 210 can be realized by using two solder resist layers 200 having different light absorptances depending on wavelengths.

  Referring to FIG. 29, an electroless plating layer S is formed on the inside of the opening 210 and on the solder resist layer 200. The electroless plating layer S can be formed to a thickness of 2 μm or less by electroless plating, and can be formed to a single layer such as copper or a double layer such as titanium and copper.

  Referring to FIG. 30, an electrolytic plating layer P for forming the first metal post 300 in the opening 210 is formed. That is, the first metal post 300 is formed of an electrolytic plating layer P using the electroless plating layer S as a lead-in wire. The height of the first metal post 300 may be lower than the height of the solder resist layer 200.

  Referring to FIG. 31, a second metal post 400 is formed on the electrolytic plated layer P of the first metal post 300. The second metal post 400 can also be formed by electrolytic plating using the electroless plating layer S as a lead-in wire. The second metal post 400 can 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 post 400.

  Referring to FIG. 33, the height of the solder resist layer 200 is reduced. The height of the solder resist layer 200 can be lowered by partially removing the solder resist layer 200 by a method such as desmear or descum. The reduced height of the solder resist layer 200 exposes the electroless plating layer 310 of the first metal post 300 to the outside.

  The height of the desmeared or descumed solder resist layer 200 can be lowered to the point where the cross sectional area of the first metal post 300 is the largest (inflection point), but is not limited thereto, and the final solder The height of the resist layer 200 may be higher or lower than the point where the cross sectional area of the first metal post 300 is the largest.

  Referring to FIG. 34, after the reflow process, the upper surface of the second metal post 400 is curved upward and a part of the second metal post 400 flows horizontally onto the electroless plating layer 310. As a result, the electroless plating layer 310 covers a portion of the side surface of the second metal post 400, and a portion of the second metal post 400 is located on the electroless plating layer 310.

  On the other hand, in the present embodiment, the cross-sectional area (width) of the opening 210 of the solder resist becomes larger as it goes from the upper surface to the lower surface and then becomes smaller. The cross-sectional area (width) of the first metal post 300 also goes from the upper surface to the lower surface. It becomes smaller and then becomes smaller.

  35 to 41 are views showing a method of manufacturing a printed circuit board according to the fifth embodiment of the present invention.

  Referring to FIG. 35, the outermost layer circuit 120 ′ and the metal pad 110 are formed on the insulating layer 100, and the solder resist layer 200 covering the outermost layer circuit 120 ′ and the metal pad 110 is stacked on the insulating layer 100. Also, an opening 210 is formed in the solder resist layer 200. The solder resist layer 200 is negative photosensitive, and the opening 210 can be formed by the exposure and development steps of a photolithography step. The opening 210 is formed on the metal pad 110, and at least a portion of the metal pad 110 can be exposed through the opening 210.

  In FIG. 35, the cross-sectional area and width of the opening 210 are shown constant from the upper surface to the lower surface, but the present invention is not limited to this shape, and the opening described in the second to fourth embodiments described above The shape of 210 can be substituted.

  Referring to FIG. 36, an electroless plating layer S is formed on the inside of the opening 210 and on the solder resist layer 200. The electroless plating layer S can be formed to a thickness of 2 μm or less by electroless plating, and can be formed to a single layer such as copper or a double layer such as titanium and copper.

  Referring to FIG. 37, an electrolytic plating layer P for forming the first metal post 300 in the opening 210 is formed. That is, the first metal post 300 is formed of an electrolytic plating layer P using the electroless plating layer S as a lead-in wire. The electrolytic plating layer P is formed to be higher than the height of the solder resist layer 200.

  Referring to FIG. 38, a second metal post 400 is formed on the electrolytic plated layer P of the first metal post 300. The second metal post 400 can also be formed by electrolytic plating using the electroless plating layer S as a lead-in wire. The second metal post 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 height of the solder resist layer 200 can be lowered by partially removing the solder resist layer 200 by a method such as desmear or descum. The reduced height of the solder resist layer 200 exposes the electroless plating layer 310 of the first metal post 300 to the outside. In addition, the side surface of the second metal post 400 is also exposed to the outside.

  Referring to FIG. 41, after the reflow process, the upper surface of the second metal post 400 is curved upward and the second metal post 400 flows horizontally onto the electroless plating layer 310.

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

  While the embodiments of the present invention have been described above, addition of, or modifications to, components can be made without departing from the concept of the present invention as set forth in the appended claims by those skilled in the art. The present invention can be variously modified and changed by deleting or adding, and so forth, which may be included within the scope of the present invention.

100, 100 ', 100''insulating layer 110 metal pad 120, 120' circuit 130 via 200, 200 'solder resist layer 210 opening 300 first metal post 310 electroless plating layer 400 second metal post 500 solder ball

Claims (17)

A metal pad formed on the insulating layer,
A solder resist layer provided with an opening exposing at least a part of the metal pad, and laminated on the insulating layer;
And a first metal post formed on the metal pad in the opening, the upper surface of which protrudes above the surface of the solder resist layer,
The printed circuit board in which the electroless plating layer was formed in the whole side and lower surface of the said 1st metal post. And a second metal post formed on the first metal post,
The printed circuit board according to claim 1, wherein the melting point of the metal forming the second metal post is lower than the melting point of the metal forming the first metal post.   The printed circuit board according to claim 2, wherein the electroless plating layer extends on at least a part of the side surface of the second metal post.   The printed circuit board according to claim 2, wherein a part of the second metal post is formed on the electroless plating layer.   The printed circuit board according to any one of claims 1 to 4, wherein the solder resist layer is in contact with the electroless plating layer formed on the side surface of the first metal post.   The printed circuit board according to any one of claims 1 to 5, wherein the width of the lower surface of the first metal post is smaller than the width of the metal pad.   The printed circuit board of claim 6, wherein a cross-sectional area of the first metal post decreases from the top surface to the bottom surface of the first metal post.   The printed circuit board according to claim 7, wherein an area of a top surface of the first metal post is equal to or larger than a cross sectional area of the metal pad.   The printed circuit board according to claim 6, wherein the cross-sectional area of the first metal post increases from the top surface to the bottom surface of the first metal post.   7. The printed circuit board according to claim 6, wherein the cross-sectional area of the first metal post increases from the upper surface to the lower surface of the first metal post.   The 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 decreases as the surface of the solder resist layer goes to the lower surface of the first metal post. 11. The printed circuit board according to claim 10.   The printed circuit board according to claim 10, wherein a width of the first metal post on a surface of the solder resist layer is equal to or more than a width of the metal pad.   The printed circuit board according to any one of claims 10 to 12, wherein the first metal post has a minimum value of the cross-sectional area at the top surface.   The printed circuit board of claim 6, wherein a cross-sectional area of the first metal post is constant from the top surface to the bottom surface of the first metal post.   The printed circuit board according to any one of claims 2 to 4, wherein the upper surface of the second metal post includes an upwardly curved curved surface.   The printed circuit board according to any one of claims 1 to 15, wherein the inclination of the side surface of the first metal post with respect to the surface of the solder resist layer is larger than zero.   The printed circuit board according to any one of claims 1 to 16, wherein the height of the solder resist layer in the peripheral region of the first metal post is larger than the height of the solder resist layer in other regions.

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