Circuit board and its manufacturing method

Abstract

A circuit board includes a circuit substrate, at least one metal pad, and a solder block provided corresponding to each of the metal pads. Each of the metal pads is disposed on one side of the circuit substrate and electrically connected to the circuit substrate. A concave portion is formed by inward concavity on the side of the metal pad facing away from the circuit substrate, and the solder block is received in the concave portion. The present invention also relates to a method for manufacturing a circuit board. In the circuit board and the method for manufacturing the same, the solder block can be accurately disposed on the metal pad.

Description

Technical Field

[0001] The present invention relates to the field of circuit boards, and more particularly to a circuit board with connection pads and a manufacturing method thereof. Background Art

[0002] Due to the rapid development of circuit boards, their applications are becoming more and more widespread. Among them, due to the development trends of high integration, miniaturization, and micro-miniaturization of electronic products, the line width and line pitch of the circuits on the circuit board are getting smaller and smaller, making the connection pads for connecting the circuit board to external components also smaller and smaller. When connecting an external component to a connection pad, usually solder paste is first coated on the surface of the connection pad, and then the external component is soldered through the solder paste. However, with the reduction of the connection pads and the line pitch, it is becoming more and more difficult to accurately coat the solder paste, and there are easily situations where the solder paste has poor contact with the connection pads and the solder paste overflows to other circuits. Summary of the Invention

[0003] In view of this, the present invention provides a circuit board to solve the above technical problems.

[0004] It also provides a manufacturing method of a circuit board to solve the above technical problems.

[0005] A circuit board includes a circuit substrate, at least one metal pad, and a solder block corresponding to each of the metal pads. Each metal pad is disposed on one side of the circuit substrate and is electrically connected to the circuit substrate. A recessed portion is formed by inwards concaving the side of the metal pad facing away from the circuit substrate, and the solder block is received in the recessed portion.

[0006] A manufacturing method of a circuit board includes the following steps:

[0007] Provide a single-sided substrate including an insulating layer and a metal foil stacked;

[0008] Press a first dry film on the side of the metal foil facing away from the insulating layer, and perform exposure and development on the first dry film to form at least one first groove, wherein a part of the metal foil is exposed from the first groove;

[0009] Plate tin in each first groove to form a solder block, and then remove the first dry film;

[0010] Press a second dry film on the side of the metal foil facing away from the insulating layer, wherein the solder block is covered by the second dry film;

[0011] Perform exposure and development on the second dry film to form a second groove corresponding to each solder block, wherein the solder block is exposed from the second groove, and the solder block is spaced from the second dry film after exposure and development;

[0012] A metal pad is plated in the second groove, wherein the metal pad covers the tin block and is filled between the tin block and the second dry film, so that a recess is formed in the metal pad to wrap the tin block;

[0013] A circuit board electrically connected to the metal pad is formed on a side of the second dry film facing away from the single-sided substrate; and

[0014] The single-sided substrate and the second dry film on the circuit board are removed.

[0015] In the circuit board and its manufacturing method of the present application, the tin block can be accurately arranged on the metal pad, and the tin block is embedded in the metal pad, which is beneficial to improving the connection stability between the tin block and the metal pad, and at the same time avoiding contact between the tin block and other circuits. Description of the Drawings

[0016] Figures 1 to 9 It is a cross-sectional schematic diagram of the manufacturing process of a circuit board according to an embodiment of the present application.

[0017] Figures 10 to 11 It is a cross-sectional schematic diagram of a partial manufacturing process of a circuit board according to an embodiment of the present application.

[0018] Figure 12 It is a cross-sectional schematic diagram of a circuit board according to another embodiment of the present application.

[0019] Figures 13 to 19 It is a cross-sectional schematic diagram of the manufacturing process of a circuit board according to another embodiment of the present application.

[0020] Description of the Main Component Symbols

[0021]

[0022]

[0023] The following specific embodiments will further illustrate the present invention in conjunction with the above drawings. Specific Embodiments

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments, and are not intended to limit this application.

[0026] Some embodiments of the present application are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined or replaced with each other.

[0027] See also Figures 1 to 11 The first embodiment of the present application provides a method for manufacturing a circuit board 100a, which includes the following steps:

[0028] Step S41, see Figure 1 , providing a single-sided substrate 10, including an insulating layer 11 and a metal foil 13 stacked together.

[0029] The insulating layer 11 is a dielectric material commonly used in the art, such as a polyimide substrate, epoxy resin, etc. Therefore, this application does not go into too much detail. The material of the metal foil 13 may include but is not limited to copper, gold, silver, etc. In this embodiment, the metal foil 13 may be a thin copper layer.

[0030] Step S42, see Figure 2 A first dry film 15 is laminated on the side of the metal foil 13 facing away from the insulating layer 11 , and the first dry film 15 is exposed and developed to form at least one first groove 150 , wherein a portion of the metal foil 13 is exposed from the first groove 150 .

[0031] In this embodiment, the subsequent description is made by taking one first groove 150 as an example. In some embodiments, a plurality of first grooves 150 arranged at intervals may be formed on the first dry film 15 .

[0032] Step S43, see Figure 3 and Figure 4 , tin is plated in each of the first grooves 150 to form a tin block 20 , and then the first dry film 15 is removed.

[0033] In this embodiment, the height of the solder block 20 is preferably less than the depth of the first groove 150, which is conducive to making the shape of the solder block 20 flat. In some embodiments, the height of the solder block 20 can also be flush with the surface of the first dry film 15 away from the single-sided substrate 10.

[0034] Step S44, see Figure 5 A second dry film 17 is laminated on a side of the metal foil 13 facing away from the insulating layer 11 , wherein the tin block 20 is covered by the second dry film 17 .

[0035] Step S45, see Figure 6, the second dry film 17 is exposed and developed to form a second groove 170 corresponding to each of the tin blocks 20, wherein the tin block 20 is exposed from the second groove 170, and the tin block 20 is spaced from the second dry film 17 after exposure and development.

[0036] Step S46, please refer to Figure 7 , a metal pad 23 is plated in the second groove 170, wherein the metal pad 23 fills between the tin block 20 and the second dry film 17 and covers the tin block 20, so that the metal pad 23 forms a recessed portion 231 to wrap the tin block 20.

[0037] In this embodiment, copper is plated in the second groove 170 to form a copper pad as the metal pad 23. In some embodiments, the metal pad 23 can also be made of other conductive metals.

[0038] In this embodiment, the metal pad 23 preferably does not protrude from the second groove 170, which is beneficial to the flatness of the outer shape structure of the metal pad 23.

[0039] Step S47, please refer to Figure 8 , a circuit board 30 electrically connected to the metal pad 23 is formed on the side of the second dry film 17 facing away from the single-sided substrate 10.

[0040] In this embodiment, the circuit board 30 may include a dielectric layer 31, a circuit layer 33, and conductive posts 35. The dielectric layer 31 is interposed between the circuit layer 33 and the second dry film 17, and the conductive posts 35 are buried in the dielectric layer 31 and electrically connect the circuit layer 33 and the metal pad 23.

[0041] In this embodiment, the circuit board 30 is a single-layer circuit board. In some embodiments, the circuit board 30 can also be a double-layer or multi-layer circuit board, that is, it can also include other circuit layers in addition to the circuit layer 33.

[0042] Step S49, please refer to Figure 9 , the single-sided substrate 10 and the second dry film 17 on the circuit board 30 are removed, and then the circuit board 100a is obtained.

[0043] Specifically, the insulating layer 11 can be first separated and removed, then the metal foil 13 can be removed by rapid etching, and then the second dry film 17 can be peeled off. It can be understood that the single-sided substrate 10 and the second dry film 17 are not limited to the above methods for removal.

[0044] In this embodiment, the circuit board 30 can be formed by, but not limited to, the following methods:

[0045] Step S471, please refer to Figure 10 , press-fit a dielectric layer 31 on the side of the second dry film 17 facing away from the single-sided substrate 10, and open a communication groove 310 corresponding to each of the metal pads 23 on the dielectric layer 31 to expose a part of the metal pad 23.

[0046] Preferably, the communication groove 310 can be arranged corresponding to the middle area of the metal pad 23.

[0047] Step S472, please refer to Figure 11 , form a conductive column 35 in the communication groove 310, wherein the conductive column 35 fills the communication groove 310 and is connected to the metal pad 23.

[0048] The conductive column 35 can be formed by, but not limited to, electroplating and other methods.

[0049] Step S473, please refer to Figure 8 , form a circuit layer 33 on the side of the dielectric layer 31 facing away from the second dry film 17, and the circuit layer 33 is electrically connected to the conductive column 35.

[0050] The second embodiment of the present application provides a method for manufacturing a circuit board 100b, the difference compared with the first embodiment is that, please refer to Figure 12 , after removing the single-sided substrate 10 and the second dry film 17 on the circuit substrate 30, the method for manufacturing the circuit board 100b further includes: removing a part of the tin block 20, so that the thickness of the tin block 20 is less than the depth of the recess 231. Wherein, part of the tin block 20 can be removed by, but not limited to, etching.

[0051] Please refer to Figure 2 and Figures 13 to 19 , the third embodiment of the present application provides a method for manufacturing a circuit board 100c, which includes the following steps:

[0052] Step S51, please refer to Figure 2 , provide a single-sided substrate 10, including an insulating layer 11 and a metal foil 13 arranged in a stacked manner, press-fit a first dry film 15 on the side of the metal foil 13 facing away from the insulating layer 11, and perform exposure and development on the first dry film 15 to form at least one first groove 150, wherein a part of the metal foil 13 is exposed from the first groove 150.

[0053] Step S52, please refer to Figure 13 and Figure 14 , sequentially stack and plate a metal block 21 and a tin block 20 in each of the first grooves 150, and then remove the first dry film 15.

[0054] In this embodiment, the solder block 20 preferably does not protrude beyond the first groove 150, which is beneficial to making the outer shapes of the solder block 20 and the metal block 21 flat. In some embodiments, the solder block 20 may also be flush with the surface of the first dry film 15 facing away from the single-sided substrate 10.

[0055] The material of the metal block 21 may include but is not limited to nickel. The material of the metal block 21 is different from that of the solder block 20 and the subsequently formed metal pad 23.

[0056] Step S53, please refer to Figure 15 , press and laminate a second dry film 17 on the side of the metal foil 13 facing away from the insulating layer 11, wherein the solder block 20 and the metal block 21 are covered by the second dry film 17.

[0057] Step S54, please refer to Figure 16 , expose and develop the second dry film 17 to form a second groove 170 corresponding to each solder block 20, wherein the solder block 20 is exposed from the second groove 170, and the solder block 20 and the metal block 21 are spaced from the second dry film 17 after exposure and development. In some embodiments, the metal block 21 may also not be spaced from the second dry film 17 after exposure and development.

[0058] Step S55, please refer to Figure 17 , plate a metal in the second groove 170 to form a metal pad 23, wherein the metal pad 23 fills the space between the solder block 20 and the metal block 21 and the second dry film 17 and covers the solder block 20, so that the metal pad 23 forms a recessed portion 231 to wrap the solder block 20 and the metal block 21.

[0059] Step S56, please refer to Figure 18 , form a circuit board 30 electrically connected to the metal pad 23 on the side of the second dry film 17 facing away from the single-sided substrate 10, wherein the circuit board 30 includes a dielectric layer 31, a circuit layer 33, and a conductive post 35. The dielectric layer 31 is interposed between the circuit layer 33 and the second dry film 17, and the conductive post 35 is embedded in the dielectric layer 31 and electrically connects the circuit layer 33 and the metal pad 23.

[0060] Step S57, please refer to Figure 19 , remove the single-sided substrate 10, the second dry film 17, and the metal block 21 on the circuit board 30, and then obtain the circuit board 100c.

[0061] Among them, the metal block 21 can be removed by but not limited to rapid etching.

[0062] Please refer toFigure 9 For a circuit board 100a according to an embodiment of the present application, it includes a circuit substrate 30, at least one metal pad 23, and a solder bump 20 provided corresponding to each of the metal pads 23. Among them, the circuit substrate 30 includes a dielectric layer 31, a circuit layer 33, and conductive vias 35. The dielectric layer 31 is sandwiched between the circuit layer 33 and the metal pad 23, and the conductive vias 35 are embedded in the dielectric layer 31 and electrically connect the circuit layer 33 and the metal pad 23. A recess 231 is formed by concaving one side of the metal pad 23 facing away from the circuit substrate 30, and the solder bump 20 is received in the recess 231.

[0063] In some embodiments, referring to Figure 12 , the height of the solder bump 20 is lower than the depth of the recess 231. In some embodiments, referring to Figure 9 and Figure 19 , the surface of the solder bump 20 facing away from the circuit substrate 30 is flush with the surface of the metal pad 23 facing away from the circuit substrate 30.

[0064] The surface of the solder bump 20 facing away from the circuit substrate 30 is flat, which is beneficial to the stability during subsequent soldering of the solder bump 20 with external components.

[0065] The surface of the metal pad 23 facing away from the circuit substrate 30 is flat, which is also beneficial to the stability during subsequent soldering of the solder bump 20 with external components.

[0066] For the circuit board and its manufacturing method of the present application, the solder bump 20 can be accurately set on the metal pad 23, and the solder bump 20 is embedded in the metal pad 23, which is beneficial to improving the connection stability between the solder bump 20 and the metal pad 23, and at the same time avoiding contact between the solder bump 20 and other circuits.

[0067] The above is only a preferred embodiment of the present invention, and it is not a limitation to any form of the present invention. Although the present invention has been disclosed as a preferred embodiment above, it is not intended to limit the present invention. Any person skilled in the art, within the scope of the technical solution of the present invention, can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for manufacturing a circuit board, comprising the following steps: Providing a single-sided substrate, including an insulating layer and a metal foil stacked; Pressing a first dry film on a side of the metal foil facing away from the insulating layer, and performing exposure and development on the first dry film to form at least one first groove, wherein a part of the metal foil is exposed from the first groove; Tin-plating in each of the first grooves to form tin blocks, and then removing the first dry film; Pressing a second dry film on a side of the metal foil facing away from the insulating layer, wherein the tin blocks are covered by the second dry film; Performing exposure and development on the second dry film to form a second groove corresponding to each of the tin blocks, wherein the tin blocks are exposed from the second groove, and the tin blocks are spaced from the second dry film after exposure and development; Plating a metal in the second groove to form a metal pad, wherein the metal pad covers the tin blocks and fills between the tin blocks and the second dry film, so that the metal pad forms a recessed portion to wrap the tin blocks; Forming a circuit board electrically connected to the metal pad on a side of the second dry film facing away from the single-sided substrate; and Removing the single-sided substrate and the second dry film on the circuit board.

2. The manufacturing method of the circuit board according to claim 1, characterized in that, After the step of "removing the single-sided substrate and the second dry film on the circuit board", it further includes: Removing a part of the tin blocks to make the thickness of the tin blocks less than the depth of the recessed portion.

3. The manufacturing method of the circuit board according to claim 1, characterized in that, The step of "tin-plating in each of the first grooves to form tin blocks, and then removing the first dry film" specifically includes: sequentially stacking and plating a metal block and a tin block in each of the first grooves, and then removing the first dry film; After the step of "removing the single-sided substrate and the second dry film on the circuit board", it further includes: Removing the metal blocks to expose the tin blocks.

4. The manufacturing method of the circuit board according to claim 3, characterized in that, After forming the second groove, the metal blocks are spaced from the second dry film after exposure and development; When forming the metal pad, the recessed portion of the metal pad wraps the tin blocks and the metal blocks.

5. The manufacturing method of the circuit board according to claim 3, characterized in that, The material of the metal blocks is different from that of the tin blocks and the metal pad.

6. The manufacturing method of the circuit board according to claim 1, characterized in that, The method for forming the circuit board includes: Pressing a dielectric layer on a side of the second dry film facing away from the single-sided substrate, and opening a communication groove corresponding to each of the metal pads on the dielectric layer to expose a part of the metal pads; Forming a conductive post in the communication groove, wherein the conductive post fills the communication groove and is connected to the metal pad; and Forming a circuit layer on a side of the dielectric layer facing away from the second dry film, and the circuit layer is electrically connected to the conductive post.

7. The manufacturing method of the circuit board according to claim 1, characterized in that The height of the tin blocks is less than or equal to the depth of the first grooves.

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