Circuit board and method for manufacturing the same

Abstract

A circuit board and a manufacturing method thereof, the circuit board comprising a first circuit substrate and a second circuit substrate, the first circuit substrate comprising a first circuit layer, a first insulating layer, and a second circuit layer, the first circuit substrate further comprising at least two spaced apart conductive blocks exposed from gaps in the first circuit layer and gaps in the second circuit layer, each conductive block comprising a first conductive portion and a second conductive portion; the second conductive portion being embedded in the first insulating layer, and the two surfaces of the second conductive portion being flush with the two sides of the first insulating layer; the first conductive portion protruding from the surface of the second conductive portion facing away from the second circuit layer, the width of the first conductive portion being smaller than the width of the second conductive portion; the second circuit substrate being coupled to the first circuit layer, the first insulating layer exposed from the first circuit layer, and the conductive blocks via a second insulating layer; the circuit board further comprising a conductive column embedded in the second insulating layer and provided corresponding to each conductive block, the first conductive portion being embedded in the conductive column, the conductive column electrically connecting the conductive block and the second circuit substrate.

Description

Technical Field

[0001] The present invention relates to a circuit board and a manufacturing method thereof. Background Art

[0002] Driven by the market trend of portable electronic products, the circuit boards used in these products are also moving towards high-density and high-precision integration. However, when mounting electronic components on circuit boards, poor circuit board flatness can easily lead to unstable electrical connections between the components and the circuit board, or even poor electrical continuity. Summary of the Invention

[0003] In view of this, it is necessary to provide a method for manufacturing a circuit board that is conducive to improving the flatness.

[0004] It is also necessary to provide a circuit board that is conducive to improving flatness.

[0005] A method for manufacturing a circuit board, comprising the following steps:

[0006] Providing a double-sided metal substrate, comprising a first metal foil, a first insulating layer, and a second metal foil stacked in sequence;

[0007] At least two spaced-apart step blind vias are formed on the double-sided metal substrate, wherein each of the step blind vias includes a first portion penetrating the first metal foil along the stacking direction and a second portion penetrating the first insulating layer along the stacking direction, the first portion is connected to the second portion, and in any cross section along the stacking direction, the width of the first portion of each step blind via is smaller than the width of the second portion;

[0008] Filling each of the stepped blind holes with a conductive paste to form a conductive block corresponding to each of the stepped blind holes, wherein each of the conductive blocks includes a first conductive portion filling the first portion and a second conductive portion filling the second portion;

[0009] Performing circuit fabrication on the first metal foil provided with the first conductive portion to form a corresponding first circuit layer;

[0010] Disposing a second insulating layer on the first circuit layer, the first insulating layer exposed from the first circuit layer, and the conductive blocks, and patterning the second insulating layer to form a first opening corresponding to each conductive block, wherein the first opening is opened around the first conductive portion to expose the first conductive portion and at least a portion of the second conductive portion; and

[0011] A conductive column filling the first opening is formed corresponding to each first opening, and a circuit substrate is formed on the patterned second insulating layer, and the second copper foil is circuit-made to form a corresponding second circuit layer, wherein the conductive column is electrically connected to the circuit substrate, and the second circuit layer forms at least one second opening corresponding to the conductive block.

[0012] A circuit board comprises a first circuit substrate and a second circuit substrate stacked together, the first circuit substrate comprising a first circuit layer, a first insulating layer, and a second circuit layer stacked in sequence along the stacking direction, the first circuit substrate further comprising at least two spaced apart conductive blocks exposed from gaps in the first circuit layer and gaps in the second circuit layer, each of the conductive blocks comprising a first conductive portion and a second conductive portion; the second conductive portion is embedded in the first insulating layer, and two surfaces of the second conductive portion spaced apart along the stacking direction are respectively flush with two sides of the first insulating layer spaced apart along the stacking direction; the first conductive portion protrudes from a surface of the second conductive portion facing away from the second circuit layer, and in any cross-section along the stacking direction, the width of the first conductive portion is smaller than the width of the second conductive portion; the second circuit substrate is coupled to the first circuit layer, the first insulating layer exposed from the first circuit layer, and the conductive blocks via a second insulating layer; the circuit board further comprises at least two spaced apart conductive posts embedded in the second insulating layer, each conductive post being arranged corresponding to one of the conductive blocks, and the first conductive portion being embedded in the conductive post, and the conductive post electrically connecting the conductive block and the second circuit substrate.

[0013] In the circuit board and its manufacturing method of the present application, because the side of the second conductive portion in each conductive block facing away from the first circuit layer is flush with the side of the first insulating layer facing away from the first circuit layer, the flatness of the circuit board is improved, thereby facilitating the stability and effectiveness of the subsequent electrical connection with electronic components. Furthermore, the first conductive portion is embedded in the conductive pillar, which helps to improve the stability of the electrical connection between circuit layers in the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figures 1-10 A method for manufacturing a circuit board according to one embodiment of the present invention is provided.

[0015] Figure 11 A circuit board according to one embodiment of the present invention is provided.

[0016] Description of main component symbols

[0017]

[0018]

[0019] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0022] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0023] Please refer to Figures 1 to 10 A method for manufacturing a circuit board according to one embodiment of the present invention comprises the following steps:

[0024] Step S1, see Figure 1 , providing a double-sided metal substrate 10, the double-sided metal substrate 10 includes a first metal foil 11, a first insulating layer 13 and a second metal foil 15 stacked in sequence.

[0025] The first insulating layer 13 may include but is not limited to at least one of a polyimide film (PI), a liquid crystal polymer film (LCP), a polyethylene terephthalate film (PET), and a polyethylene naphthalate film (PEN).

[0026] The material of the first metal foil 11 and the second metal foil 15 can be, but is not limited to, at least one of copper, silver, nickel, gold and alloys thereof.

[0027] In this embodiment, the double-sided metal substrate 10 may be a double-sided copper clad laminate.

[0028] Step S2, see Figure 2At least two stepped blind vias 16 are formed on the double-sided metal substrate 10, wherein each stepped blind via 16 includes a first portion 161 that penetrates the first metal foil 11 along the stacking direction and a second portion 163 that penetrates the first insulating layer 13 along the stacking direction. The first portion 161 is connected to the second portion 163, and in any cross section along the stacking direction, the width of the first portion 161 in each stepped blind via 16 is smaller than the width of the second portion 163.

[0029] Preferably, in any cross section along the stacking direction, the cross section of each stepped blind hole 16 is substantially in the shape of an inverted T. More preferably, the central axis of the first portion 161 in each stepped blind hole 16 coincides with the central axis of the second portion 163 .

[0030] Specifically, the stepped blind hole 16 can be formed by, but not limited to, the following methods:

[0031] First, see Figure 3 , the first metal foil 11 is etched to form at least two first portions 161 penetrating the first metal foil 11 along the stacking direction.

[0032] Second, see Figure 2 The first insulating layer 13 is etched through each first portion 161 to form a second portion 163 that penetrates the first insulating layer 13 along the stacking direction. In any cross section along the stacking direction, the width of the first portion 161 is smaller than the width of the corresponding second portion 163.

[0033] Since the first metal foil 11 and the first insulating layer 13 are made of different materials, the first portion 161 and the second portion 163 can be formed respectively by selecting different etching solutions, and the formation of the second portion 163 does not affect the already formed first portion 161 .

[0034] Step S3, see Figure 4 , a conductive paste is filled into each of the stepped blind vias 16 to form a conductive block 20 corresponding to each of the stepped blind vias 16. Each of the conductive blocks 20 includes a first conductive portion 21 filling the first portion 161 and a second conductive portion 23 filling the second portion 163. The shape of each conductive block 20 is consistent with the shape of the corresponding stepped blind via 16.

[0035] Preferably, the conductive paste may be silver paste. The conductive paste may be filled into the stepped blind via 16 by, but not limited to, printing.

[0036] Step S4, see Figure 5, circuit manufacturing is performed on the first metal foil 11 having the first conductive portion 21 , so that the first metal foil 11 forms a corresponding first circuit layer 110 .

[0037] When the circuits in the first circuit layer 110 are electrically connected to the conductive block 20, due to the special structure of the conductive block 20, the circuits can be directly disposed on the surface of the second conductive portion 21 of the conductive block 20 to achieve electrical connection, without forming an annular ring, thereby saving wiring space and improving wiring density. In some embodiments, to further enhance the stability of the electrical connection between the circuits and the conductive block 20, the circuits can further contact or even surround the first conductive portion 23.

[0038] Step S5, see Figure 6 and Figure 7 A second insulating layer 30 is disposed on the first circuit layer 110, the first insulating layer 13 exposed from the first circuit layer 110, and the conductive blocks 20. The second insulating layer 30 is patterned to form a first opening 301 corresponding to each conductive block 20. The first opening 301 surrounds the first conductive portion 21 to expose the first conductive portion 21 and a portion of the second conductive portion 23.

[0039] In this embodiment, preferably, along the stacking direction, the thickness of the second insulating layer 30 may be greater than the height of the first conductive portion 21. In some embodiments, along the stacking direction, the thickness of the second insulating layer 30 may also be less than or equal to the height of the first conductive portion 21.

[0040] Step S6, see Figure 8 A conductive pillar 35 is formed corresponding to each first opening 301 to fill the first opening 301. A circuit substrate 50 is formed on the side of the patterned second insulating layer 30 facing away from the first insulating layer 13. The second metal foil 15 is then subjected to circuit fabrication to form a corresponding second circuit layer 150. The conductive pillar 35 is electrically connected to the circuit substrate 50, and the second circuit layer 150 forms at least one second opening 151 corresponding to the conductive block 20.

[0041] Specifically, the surface of each conductive pillar 35 facing the corresponding second conductive portion 23 is recessed in a direction away from the second conductive portion 23 to form a groove 350 , and the corresponding first conductive portion 21 is embedded in the groove 350 .

[0042] At least one conductive block 20 is exposed from a second opening 151. In this embodiment, there are multiple conductive blocks 20 spaced apart, and the multiple conductive blocks 20 are exposed from a second opening 151. The surface of the second conductive portion 23 of each conductive block 20 facing away from the first conductive portion 21 is flush with the side of the first insulating layer 13 facing away from the first circuit layer 110.

[0043] In this embodiment, the circuit substrate 50 may be a single-layer circuit substrate including a circuit layer 53. The conductive pillars 35 electrically connect the circuit layer 53. In some embodiments, the circuit substrate 50 may also be a double-layer circuit substrate or a multi-layer circuit substrate, that is, the circuit substrate 50 includes at least two circuit layers spaced apart and stacked. The conductive pillars 35 electrically connect adjacent circuit layers.

[0044] Step S7, see Figure 9 A first protective layer 61 is covered on the circuit substrate 50, and a second protective layer 63 is covered on the second circuit layer 150. The second protective layer 63 includes at least one window 630, and at least one conductive block 20 is exposed from one of the windows 630.

[0045] In this embodiment, a plurality of the conductive blocks 20 are exposed from one of the openings 630 .

[0046] Step S8, see Figure 10 At least one electronic component 70 is installed in the window 630 , and each electronic component 70 is electrically connected to at least two of the conductive blocks 20 .

[0047] Specifically, each of the electronic components 70 may include at least two spaced connection pads 71 ​​, and each connection pad 71 is electrically connected to a surface of the second conductive portion 23 of the conductive block 20 that faces away from the first conductive portion 21 .

[0048] Each of the electronic components 70 and each of the conductive blocks 20 may be electrically connected and fixed via, but not limited to, anisotropic conductive adhesive or solder paste (not shown).

[0049] In some embodiments, the above step S8 may be omitted. In some embodiments, the above steps S7 and S8 may be omitted.

[0050] See also Figure 11A circuit board 100 according to one embodiment of the present invention includes a first circuit substrate 10a and a second circuit substrate 40 stacked in layers. The first circuit substrate 10a includes a first circuit layer 110, a first insulating layer 13, and a second circuit layer 150 stacked in sequence along the stacking direction. The first circuit substrate 10a further includes at least two spaced conductive blocks 20 exposed from gaps in the first circuit layer 110 and the second circuit layer 150. Each conductive block 20 includes a first conductive portion 21 and a second conductive portion 23. The second conductive portion 23 is embedded in the first insulating layer 13, and the two surfaces of the second conductive portion 23 spaced apart along the stacking direction are flush with the two sides of the first insulating layer 13 spaced apart along the stacking direction. The first conductive portion 21 protrudes from the surface of the second conductive portion 23 facing away from the second circuit layer 150, and in any cross-section along the stacking direction, the width of the first conductive portion 21 is less than the width of the second conductive portion 23. The second circuit substrate 40 is bonded to the first circuit layer 110, the first insulation layer 13 exposed from the first circuit layer 110, and the conductive blocks 20 via a second insulation layer 30. The circuit board 100 further includes at least two spaced apart conductive pillars 35 embedded in the second insulation layer 30. Each conductive pillar 35 corresponds to a conductive block 20, and the first conductive portion 21 is embedded in the conductive pillar 35. The conductive pillars 35 electrically connect the conductive blocks 20 and the second circuit substrate 40.

[0051] In this embodiment, along the stacking direction, the height of the first conductive portion 21 may be consistent with the thickness of the first circuit layer 110 .

[0052] Preferably, the conductive block 20 may be a silver block.

[0053] Preferably, at any cross section along the stacking direction, the cross section of each conductive block 20 is substantially in an inverted T-shape. More preferably, the central axis of the first conductive portion 21 in each conductive block 20 along the stacking direction coincides with the central axis of the second conductive portion 23 along the stacking direction.

[0054] Preferably, along the stacking direction, the thickness of the second insulating layer 30 may be greater than the height of the first conductive portion 21. In some embodiments, along the stacking direction, the thickness of the second insulating layer 30 may also be less than or equal to the height of the first conductive portion 21.

[0055] In some embodiments, the circuit board 100 may further include a first protective layer 61 and a second protective layer 63. The first protective layer 61 covers the second circuit substrate 40, and the second protective layer 63 covers the second circuit layer 150. The second protective layer 63 includes at least one window 630 to expose the conductive block 20.

[0056] In some embodiments, the circuit board 100 may further include at least one electronic component 70 installed in the window 630 , and each electronic component 70 is electrically connected to the conductive block 20 .

[0057] Specifically, each of the electronic components 70 may include at least two spaced connection pads 71 ​​, and each connection pad 71 is electrically connected to a surface of the second conductive portion 23 of the conductive block 20 that faces away from the first conductive portion 21 .

[0058] Each of the electronic components 70 and each of the conductive blocks 20 may be electrically connected and fixed via, but not limited to, anisotropic conductive adhesive or solder paste.

[0059] In the circuit board and its manufacturing method of the present application, because the side of the second conductive portion 23 in each conductive block 20 facing away from the first circuit layer 110 is flush with the side of the first insulating layer 13 facing away from the first circuit layer 110, the flatness of the circuit board is improved, thereby facilitating the stability and effectiveness of the electrical connection with the electronic component 70 during subsequent electrical connection. Furthermore, the first conductive portion 21 is embedded in the conductive pillar 35, which helps to improve the stability of the electrical connection between circuit layers in the circuit board.

[0060] Furthermore, the conductive block 20 is formed by silver paste, which is beneficial to reducing the contact resistance of the conductive block 20, and thus is beneficial to ensuring the integrity of the circuit board signal. At the same time, the conductive block 20 formed by silver paste does not need to be surface treated and can be directly electrically connected to electronic components later, which is beneficial to reducing process steps and costs.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still 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 double-sided metal substrate, comprising a first metal foil, a first insulating layer, and a second metal foil stacked in sequence; At least two spaced-apart stepped blind vias are formed on the double-sided metal substrate, wherein each of the stepped blind vias includes a first portion penetrating the first metal foil along the stacking direction and a second portion penetrating the first insulating layer along the stacking direction, the first portion is connected to the second portion, and in any cross section along the stacking direction, the width of the first portion of each stepped blind via is smaller than the width of the second portion; Filling each of the stepped blind holes with a conductive paste to form a conductive block corresponding to each of the stepped blind holes, wherein each of the conductive blocks includes a first conductive portion filling the first portion and a second conductive portion filling the second portion; Performing circuit fabrication on the first metal foil provided with the first conductive portion to form a corresponding first circuit layer; Disposing a second insulating layer on the first circuit layer, the first insulating layer exposed from the first circuit layer, and the conductive blocks, and patterning the second insulating layer to form a first opening corresponding to each conductive block, wherein the first opening is opened around the first conductive portion to expose the first conductive portion and at least a portion of the second conductive portion; and A conductive column filling the first opening is formed corresponding to each first opening, and a circuit substrate is formed on the patterned second insulating layer, and the second metal foil is circuit-made to form a corresponding second circuit layer, wherein the conductive column is electrically connected to the circuit substrate, and the second circuit layer forms at least one second opening corresponding to the conductive block.

2. The method for manufacturing a circuit board according to claim 1, wherein: On any cross section along the stacking direction, the cross section of each of the stepped blind holes is in an inverted T shape.

3. The method for manufacturing a circuit board according to claim 1, wherein: The conductive paste is silver paste.

4. The method for manufacturing a circuit board according to claim 1, wherein: Also includes: A first protective layer is covered on a side of the circuit substrate away from the first circuit layer, and a second protective layer is covered on the second circuit layer, wherein the second protective layer includes at least one window to expose the conductive block.

5. The method for manufacturing a circuit board according to claim 4, wherein: At least one electronic component is installed in the window, and each of the electronic components is electrically connected to at least two of the conductive blocks.

6. The method for manufacturing a circuit board according to claim 5, wherein: Each of the electronic components is electrically connected and fixed to each of the conductive blocks via anisotropic conductive adhesive or solder paste.

7. A circuit board comprising a first circuit substrate and a second circuit substrate stacked together, wherein the first circuit substrate comprises a first circuit layer, a first insulating layer, and a second circuit layer stacked in sequence along a stacking direction, and the first circuit substrate further comprises at least two spaced conductive blocks exposed from gaps in the first circuit layer and gaps in the second circuit layer, characterized in that: Each of the conductive blocks includes a first conductive part and a second conductive part; the second conductive part is embedded in the first insulating layer, and the two surfaces of the second conductive part spaced apart along the stacking direction are respectively flush with the two sides of the first insulating layer spaced apart along the stacking direction; the first conductive part protrudes from the surface of the second conductive part away from the second circuit layer, and on any cross-section along the above-mentioned stacking direction, the width of the first conductive part is smaller than the width of the second conductive part; the second circuit substrate is combined with the first circuit layer, the first insulating layer exposed from the first circuit layer and the conductive block through a second insulating layer; the circuit board also includes at least two spaced conductive columns embedded in the second insulating layer, each conductive column is arranged corresponding to one of the conductive blocks, and the first conductive part is embedded in the conductive column, and the conductive column electrically connects the conductive block and the second circuit substrate.

8. The circuit board according to claim 7, wherein: On any cross section along the stacking direction, the cross section of each conductive block is in an inverted T shape; the conductive block is a silver block.

9. The circuit board according to claim 7, wherein: The circuit board also includes a first protective layer and a second protective layer. The first protective layer is arranged on a side of the second circuit substrate away from the first circuit substrate. The second protective layer covers the second circuit layer, and the second protective layer includes at least one window to expose the conductive block.

10. The circuit board according to claim 9, wherein: The circuit board further includes at least one electronic component installed in the window, and each electronic component is electrically connected and fixed to each conductive block via anisotropic conductive adhesive or solder paste.

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