Package substrate and method of manufacturing the same

Abstract

The application provides a packaging substrate and a manufacturing method thereof. The application sets a film column in the first window of the protective layer, and sets a metal layer on the film column after secondary film pressing, so as to obtain a bump. Since the bump is obtained by setting the metal layer on the film column instead of being directly electroplated in the first window, the thickness and height of the metal layer formed by electroplating can be reduced due to the existence of the film column, that is, the difficulty of electroplating and the probability of skip plating are reduced, so that a bump with a finer pitch and a higher aspect ratio can be manufactured, and the uniformity of the metal layer can be improved.

Description

Technical Field

[0001] This application relates to the field of packaging technology, and in particular to a packaging substrate and its manufacturing method. Background Technology

[0002] Bumping technology involves creating bumps on a chip to provide "point" interfaces for electrical interconnection. It is widely used in advanced packaging technologies such as flip-chip (FC), wafer-level packaging (WLP), chip-level packaging (CSP), and 3D packaging. Copper pillar bumping is a manufacturing technique that uses copper pillars to replace wire bonding for electrical interconnection between the chip and the substrate. Copper pillar bumping can shorten the length of connection circuits, reduce chip package size, and also has better conductivity, thermal conductivity, and resistance to electron migration, making it widely applicable.

[0003] In recent years, with the increase in chip integration and the emergence of fine-pitch and ultra-fine-pitch chips, bump manufacturing technology has been continuously developing towards high density and micro-pitch. When manufacturing copper pillar bumps with a diameter of 50μm or even smaller, or copper pillar bumps with a high aspect ratio, current operating methods cannot meet production needs, and severe plating skips will occur during electroplating (referring to the phenomenon that the metal layer fails to uniformly cover the substrate surface during the electroplating process, resulting in localized areas of uncovered or poorly covered areas).

[0004] Therefore, how to produce copper pillar bumps with finer pitch and higher aspect ratio has become a problem that industry professionals urgently need to solve. Summary of the Invention

[0005] In view of this, this application proposes a method for manufacturing a packaging substrate to produce bumps with finer pitch and higher aspect ratio.

[0006] In addition, it is necessary to propose a packaging substrate manufactured by this method.

[0007] A method for manufacturing a packaging substrate includes the following steps: laminating a first dry film onto a substrate; wherein the substrate includes pads and a protective layer, the protective layer having a first opening through which the pads are exposed; exposing and developing the first dry film to form a second opening on the first dry film, wherein the first dry film not removed in the second opening forms a film pillar, the film pillar being connected to the pads; depositing a first metal layer on the surface of the film pillar; laminating a second dry film onto the surface of the first dry film opposite to the protective layer; exposing and developing the second dry film to form a third opening through which the film pillar is exposed; depositing a second metal layer on the first metal layer on the surface of the film pillar, the film pillar, the first metal layer on the surface of the film pillar, and the second metal layer together forming a bump; and removing the first dry film and the second dry film to obtain the packaging substrate.

[0008] In one embodiment, the metal layer includes a first portion located within the first opening, a second portion connected to the first portion and covering the surface of the protective layer, and a third portion connected to the second portion. Along the extension direction of the substrate, the second portion protrudes beyond the third portion.

[0009] In one embodiment, along the extension direction of the substrate, the length of the second window is greater than the length of the first window, and the length of the third window is greater than the length of the first window and less than the length of the second window.

[0010] In one embodiment, in the step of setting a first metal layer on the surface of the membrane column, the first metal layer is further set on the surface of the first dry film, the inner wall of the first window, and the inner wall of the second window.

[0011] In one embodiment, the step of removing the first dry film and the second dry film further includes: removing the second dry film with a stripping solution; removing the first metal layer on the surface of the first dry film with an etching solution, and removing the first metal layer inside the second opening; and removing the first dry film with the stripping solution.

[0012] In one embodiment, the stripping solution comprises a sodium hydroxide solution.

[0013] In one embodiment, the etching solution includes an acidic copper chloride etching solution or an alkaline copper chloride etching solution.

[0014] An encapsulation substrate includes a core board, a dielectric layer, a circuit layer, a protective layer, and bumps. The dielectric layer is located on the surface of the core board. The circuit layer is formed on the surface of the dielectric layer and includes pads. The protective layer covers the circuit layer and has a first opening corresponding to the pads. The bumps are electrically connected to the pads and protrude from the surface of the protective layer away from the dielectric layer. The bumps include a dry film and a metal layer disposed on the surface of the dry film, with a portion of the dry film and a portion of the metal layer located within the first opening.

[0015] In one embodiment, the metal layer includes a first portion located within the first opening, a second portion connected to the first portion and covering the surface of the protective layer, and a third portion connected to the second portion. Along the extension direction of the packaging substrate, the second portion protrudes beyond the third portion.

[0016] In one embodiment, the metal layer comprises copper.

[0017] This application creates bumps by setting film pillars (dry films) within the first opening of the protective layer, followed by secondary lamination and then depositing a metal layer on the film pillars (dry films). Since the bumps are obtained by depositing a metal layer on the film pillars, rather than by direct electroplating within the first opening, the presence of the film pillars reduces the thickness and height of the electroplated metal layer, thus lowering the difficulty of electroplating and the probability of skipped plating. Therefore, bumps with finer spacing and higher aspect ratios can be produced, and the uniformity of the metal layer can also be improved. Attached Figure Description

[0018] Figure 1 A cross-sectional view of a substrate provided in one embodiment of this application.

[0019] Figure 2 In order to be in Figure 1 A cross-sectional view of the first dry film laminated on the substrate shown.

[0020] Figure 3 To Figure 2 A cross-sectional view of the first dry film of the structure shown being exposed and developed.

[0021] Figure 4 In order to be in Figure 3 The diagram shows a cross-sectional view of the structure with a first metal layer.

[0022] Figure 5 In order to be in Figure 4 The cross-sectional view of the structure shown shows the second dry film being pressed together.

[0023] Figure 6 To Figure 5 A cross-sectional view of the second dry film of the structure shown being exposed and developed.

[0024] Figure 7 In order to be in Figure 6 A cross-sectional view of the structure shown, in which a second metal layer is disposed on the first metal layer.

[0025] Figure 8 To remove Figure 7 A cross-sectional view of the encapsulation substrate obtained by the first and second dry films of the structure shown in one embodiment.

[0026] Explanation of main component symbols

[0027] Packaging substrate 100

[0028] Substrate 10

[0029] Core board 11

[0030] Dielectric layer 12

[0031] Line layer 13

[0032] Protective layer 14

[0033] Pad 15

[0034] First window opening 140

[0035] First dry film 20

[0036] Membrane column 21

[0037] Second window 201

[0038] Metal layer 30

[0039] First metal layer 31

[0040] Second metal layer 32

[0041] Part 1, 301

[0042] Part 2, 302

[0043] Part 3, 303

[0044] Second dry film 40

[0045] Third window 401

[0046] Bump 50

[0047] Dry film 60

[0048] The following detailed description, in conjunction with the accompanying drawings, further illustrates the embodiments of this application. Detailed Implementation

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this application pertain. The terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the embodiments of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0050] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0051] It will be understood that when a layer is referred to as "on" another layer, it can be directly on that other layer or there may be an intermediate layer in between. Conversely, when a layer is referred to as "directly on" another layer, there is no intermediate layer. When a component is referred to as "attached to," "mounted to," "set on," or "connected to" another component, it can be directly on that other component or there may be an intervening component. The term "and / or" as used herein includes all and any combination of one or more of the associated listed items.

[0052] Embodiments of this application are described herein with reference to cross-sectional views, which are schematic diagrams of idealized embodiments (and intermediate configurations) of this application. Therefore, variations in the shapes illustrated due to manufacturing processes and / or tolerances are foreseeable. Consequently, embodiments of this application should not be construed as limited to the specific shapes of the areas illustrated herein, but should include, for example, deviations in shape due to manufacturing processes. The areas shown in the figures are merely illustrative, and their shapes are not intended to represent the actual shapes of the illustrated devices, nor are they intended to limit the scope of this application.

[0053] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0054] Please see Figures 1 to 8 The first aspect of this application provides a method for manufacturing a packaging substrate 100, including the following steps: S10 to S70.

[0055] Please see Figure 1 and Figure 2 S10, a first dry film 20 is laminated onto the substrate 10.

[0056] like Figure 1As shown, in some embodiments, substrate 10 may include a core board 11, a dielectric layer 12, a circuit layer 13, and a protective layer 14. The core board 11 serves as the basic framework of the packaging substrate 100, providing mechanical support for the packaged electronic device (such as a chip). The dielectric layer 12 is located on the surface of the core board 11, and the circuit layer 13 is formed on the surface of the dielectric layer 12, including pads 15. The protective layer 14 covers the circuit layer 13 and the surface of the dielectric layer 12 exposed from the circuit layer 13. The protective layer 14 has a first opening 140 through which at least a portion of the surface of the pads 15 is exposed. The protective layer 14 may be, but is not limited to, a solder resist (also known as solder mask or green paint).

[0057] Figure 1 The illustration shows an embodiment where the substrate 10 includes a dielectric layer 12 and two circuit layers 13. In other embodiments, the substrate 10 may include multiple dielectric layers 12 and multiple circuit layers 13, with a dielectric layer 12 disposed between adjacent circuit layers 13. A protective layer 14 is located on the surface of the outermost circuit layer 13. The dielectric layer 12 may be, but is not limited to, PP (prepreg).

[0058] like Figure 2 As shown, the first dry film 20 is pressed onto the surface of the protective layer 14 away from the dielectric layer 12 and fills the first opening 140.

[0059] Please see Figure 3 S20, the first dry film 20 is exposed and developed to form a second opening 201 on the first dry film 20. The second opening 201 contains portions of the first dry film 20 that have not been removed; these portions of the first dry film 20 form film pillars 21, which are connected to pads 15. There are gaps between the film pillars 21 and the sidewalls of the first opening 140, and also gaps between the film pillars 21 and the sidewalls of the second opening 201.

[0060] In some embodiments, when exposing the first dry film 20, a light-shielding sheet can be placed around the position of the pre-formed film pillars 21 on the first dry film 20, and then the portion of the pre-formed film pillars 21 and the remaining portion are exposed. The portion where the light-shielding sheet is placed is not exposed and will be removed in the subsequent development step, thereby forming the second window 201. The shape of the second window 201 can be, but is not limited to, a regular or irregular shape such as a circle or square, and this application does not impose any limitations.

[0061] In some embodiments, such as Figure 3 As shown, the second window 201 communicates with the first window 140, and the orthographic projection of the second window 201 onto the substrate 10 can cover the first window 140. Along the extending direction of the substrate 10 (i.e.,...) Figure 3In the horizontal direction, the length of the second window 201 is greater than the length of the first window 140. The extension direction of the substrate 10 can be either the length direction or the width direction of the substrate 10, and this application does not impose any limitation.

[0062] It is understood that "membrane column 21" is merely a commonly used name and does not mean that the shape of the membrane column 21 can only be cylindrical. The membrane column 21 can also be a triangular prism, a square prism, or other prismatic shapes, and this application does not impose any restrictions.

[0063] Please see Figure 4 S30, a first metal layer 31 may be formed on the surface (including the top and side surfaces) of the film pillar 21 by means of, but not limited to, sputtering. The first metal layer 31 may be, but is not limited to, copper.

[0064] like Figure 4 As shown, during the sputtering process, the surface of the first dry film 20, the inner wall (including the sidewalls and bottom wall) of the first window 140, and the inner wall (including the sidewalls and bottom wall) of the second window 201 are also coated with a first metal layer 31. In some embodiments, the first metal layer 31 is also referred to as a seed layer, which facilitates subsequent electroplating to form a thicker metal layer 30.

[0065] Please see Figure 5 S40, a second dry film 40 is pressed onto the surface of the first dry film 20 opposite to the protective layer 14. The second dry film 40 covers the film column 21 and fills the gap between the film column 21 and the first window 140 and the second window 201.

[0066] Please see Figure 6 S50, the second dry film 40 is exposed and developed to form a third window 401 on the second dry film 40, and the film pillar 21 is exposed from the third window 401.

[0067] In some embodiments, such as Figure 6 As shown, the second dry film 40 between the membrane pillar 21 and the sidewall of the first opening 140 is removed, exposing the first opening 140 again. The second dry film 40 between the membrane pillar 21 and the sidewall of the second opening 201 is partially removed, with the removed portion communicating with the first opening 140. Along the extending direction of the substrate 10 (i.e.... Figure 6 (in the horizontal direction), the length of the third window 401 is greater than the length of the first window 140 and less than the length of the second window 201.

[0068] Please see Figure 7S60, a second metal layer 32 may be deposited on the first metal layer 31 on the surface of the membrane pillar 21 by means of, but not limited to, electroplating. The membrane pillar 21, the first metal layer 31 and the second metal layer 32 on the surface of the membrane pillar 21 together form a bump 50. The bump 50 is electrically connected to the pad 15, and the diameter of the bump 50 may be as small as 50 μm (≤50 μm). The second metal layer 32 may be, but is not limited to, copper.

[0069] like Figure 7 and Figure 8 As shown, the first metal layer 31 and the second metal layer 32 on the surface of the membrane pillar 21 together form the metal layer 30. Depending on their location, the metal layer 30 can be divided into a first portion 301, a second portion 302, and a third portion 303. The first portion 301 is located within the first opening 140, filling the gap between the membrane pillar 21 and the first opening 140. The first portion 301 is in direct contact with the pad 15, thus achieving electrical conductivity with the pad 15. The second portion 302 is connected to the first portion 301 and covers the surface of the protective layer 14; the remainder is the third portion 303. Along the extension direction of the substrate 10 (i.e.,...) Figure 7 and Figure 8 (Horizontally) the second part 302 protrudes from the third part 303. That is, when the protrusion 50 is cylindrical in shape, the diameter of the third part 303 is smaller than the diameter of the second part 302. The first part 301 located within the first opening 140 and the protruding second part 302 are equivalent to embedding the protrusion 50 entirely within the first opening 140, which helps to improve the stability of the protrusion 50.

[0070] Please see Figure 8 S70, remove the first dry film 20 and the second dry film 40 to obtain the encapsulation substrate 100.

[0071] In some embodiments, the second dry film 40 can be removed first by stripping solution, then the first metal layer 31 on the surface of the first dry film 20 and the first metal layer 31 in the second window 201 can be removed by etching solution, and finally the first dry film 20 can be removed by stripping solution.

[0072] Furthermore, the stripping solution can be a strong alkaline solution, such as a sodium hydroxide solution.

[0073] Furthermore, the etching solution can be either acidic or alkaline copper chloride etching solution. The components and their contents of the acidic copper chloride etching solution can be: copper chloride 130–180 g / L, hydrochloric acid (concentration 30%–38%) 120–200 g / L, oxidant (can be sodium hypochlorite) 120–250 g / L, industrial salt (can be sodium chloride or ammonium chloride) 150–250 g / L, stabilizer (can be urea or thiourea) 0.5–15 g / L, accelerator (can be potassium chloride) 5–30 g / L, buffer (can be sodium hydroxide) 0.05–0.2 g / L, with the remainder being water.

[0074] Please continue reading. Figure 8 This application provides a packaging substrate 100, including a core board 11, a dielectric layer 12, a circuit layer 13, a protective layer 14, and bumps 50. The core board 11 serves as the basic framework of the packaging substrate 100, providing mechanical support for the packaged electronic device (such as a chip). The dielectric layer 12 is located on the surface of the core board 11, and the circuit layer 13 is formed on the surface of the dielectric layer 12, including pads 15. The protective layer 14 covers the circuit layer 13 and the surface of the dielectric layer 12 exposed from the circuit layer 13. The protective layer 14 has a first opening 140, which corresponds to the pads 15 (i.e., the orthographic projection of the pads 15 onto the protective layer 14 is at least partially located within the first opening 140). The protective layer 14 may be, but is not limited to, a solder resist (also known as solder mask or green paint). The bumps 50 are electrically connected to the pads 15 and protrude from the surface of the protective layer 14 away from the dielectric layer 12. The bump 50 includes a dry film 60 and a metal layer 30 disposed on the surface of the dry film 60 (including the upper surface and the side surface), with a portion of the dry film 60 and a portion of the metal layer 30 located within the first opening 140. The dry film 60 and the metal layer 30 located within the first opening 140 are in direct contact with the pad 15, thereby electrically connecting the bump 50 to the pad 15. The diameter of the bump 50 can be less than or equal to 50 μm.

[0075] In some embodiments, such as Figure 8 As shown, depending on their location, the metal layer 30 can be divided into a first portion 301, a second portion 302, and a third portion 303. The first portion 301 is located within the first opening 140, filling the gap between the dry film 60 and the first opening 140. The first portion 301 directly contacts the pad 15, thus achieving electrical conductivity with the pad 15. The second portion 302 is connected to the first portion 301 and covers the surface of the protective layer 14; the remainder is the third portion 303. Along the extending direction of the packaging substrate 100 (i.e.,...) Figure 8(Horizontally) the second part 302 protrudes from the third part 303. That is, when the protrusion 50 is cylindrical in shape, the diameter of the third part 303 is smaller than the diameter of the second part 302. The first part 301 located within the first opening 140 and the protruding second part 302 are equivalent to embedding the protrusion 50 entirely within the first opening 140, which helps to improve the stability of the protrusion 50.

[0076] In some embodiments, the metal layer 30 may be copper.

[0077] The packaging substrate 100 and its manufacturing method provided in this application embodiment obtain bumps 50 by setting film pillars 21 (dry film 60) in the first window 140 of the protective layer 14, and then setting a metal layer 30 on the film pillars 21 (dry film 60) after secondary lamination. Since the bumps 50 are obtained by setting the metal layer 30 on the film pillars 21, rather than by direct electroplating in the first window 140, the presence of the film pillars 21 can reduce the thickness and height of the electroplated metal layer 30, that is, reduce the difficulty of electroplating and the probability of skipping plating. Therefore, it is possible to manufacture bumps 50 with finer pitch and higher aspect ratio, and the uniformity of the metal layer 30 can also be improved.

[0078] The above description describes some specific embodiments of this application, but in actual applications, the application should not be limited to these embodiments. For those skilled in the art, other modifications and alterations made based on the technical concept of this application should fall within the protection scope of this application.

Claims

1. A method for manufacturing a packaging substrate, characterized in that, Includes the following steps: A first dry film is laminated onto a substrate; wherein the substrate includes pads and a protective layer, the protective layer having a first opening through which the pads are exposed; The first dry film is exposed and developed to form a second opening on the first dry film. The first dry film that is not removed in the second opening forms a film pillar, and the film pillar is connected to the pad. A first metal layer is disposed on the surface of the membrane column; A second dry film is pressed onto the surface of the first dry film that is opposite to the protective layer; The second dry film is exposed and developed to form a third window on the second dry film, through which the film pillar is exposed; A second metal layer is disposed on the first metal layer on the surface of the membrane column, and the membrane column, the first metal layer on the surface of the membrane column and the second metal layer together form a bump; Remove the first dry film and the second dry film to obtain the encapsulation substrate.

2. The method for manufacturing a packaging substrate as described in claim 1, characterized in that, The metal layer includes a first portion located within the first opening, a second portion connected to the first portion and covering the surface of the protective layer, and a third portion connected to the second portion; the second portion protrudes from the third portion along the extension direction of the substrate.

3. The method for manufacturing a packaging substrate as described in claim 1, characterized in that, Along the extension direction of the substrate, the length of the second window is greater than the length of the first window, and the length of the third window is greater than the length of the first window and less than the length of the second window.

4. The method for manufacturing a packaging substrate as described in claim 1, characterized in that, In the step of setting a first metal layer on the surface of the membrane column, the first metal layer is also set on the surface of the first dry film, the inner wall of the first window, and the inner wall of the second window.

5. The method for manufacturing a packaging substrate as described in claim 4, characterized in that, The step of removing the first dry film and the second dry film further includes: The second dry film is removed using a stripping solution; The first metal layer on the surface of the first dry film is removed by etching solution, and the first metal layer inside the second opening is also removed. The first dry film is removed by the stripping solution.

6. The method for manufacturing a packaging substrate as described in claim 5, characterized in that, The stripping solution includes a sodium hydroxide solution.

7. The method for manufacturing a packaging substrate as described in claim 5, characterized in that, The etching solution includes either acidic copper chloride etching solution or alkaline copper chloride etching solution.

8. A packaging substrate, characterized in that, The substrate is formed by the manufacturing method according to any one of claims 1 to 7, and the packaging substrate comprises: Core board; The dielectric layer is located on the surface of the core plate; A circuit layer is formed on the surface of the dielectric layer, the circuit layer including pads; A protective layer covering the circuit layer, the protective layer having a first opening corresponding to the solder pads; and A bump, electrically connected to the pad and protruding from the surface of the protective layer away from the dielectric layer, the bump comprising a dry film and a metal layer disposed on the surface of the dry film, a portion of the dry film and a portion of the metal layer being located within the first opening.

9. The packaging substrate as described in claim 8, characterized in that, The metal layer includes a first portion located within the first window, a second portion connected to the first portion and covering the surface of the protective layer, and a third portion connected to the second portion; Along the extension direction of the packaging substrate, the second portion protrudes from the third portion.

10. The packaging substrate as described in claim 8, characterized in that, The metal layer includes copper.

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