Circuit board, method for manufacturing the same, and circuit board connection structure

Abstract

A circuit board, a manufacturing method thereof and a circuit board connecting structure. The circuit board comprises a circuit substrate. The circuit substrate comprises at least one circuit layer. The circuit board further comprises a plurality of conductive pads and an insulating layer. The circuit substrate is provided with a through slot, and the conductive pads are arranged in the through slot and electrically connected to the circuit layer. The thickness direction of the circuit substrate is defined as a first direction, and each of the conductive pads is provided with an opening along the first direction. The insulating layer is arranged in the through slot and fills the gap between adjacent conductive pads. The application is beneficial to the smooth entry of conductive paste into the opening to prevent short circuit problems, meet the current carrying demand of large current, and facilitate heat dissipation.

Description

Technical Field

[0001] This application relates to the field of circuit board technology, and in particular to a circuit board, a method for manufacturing the circuit board, and a circuit board connection structure having the circuit board. Background Technology

[0002] With the widespread application of printed circuit boards (PCBs) in the electronics field, it is often necessary to connect two or more PCBs with different functions to maximize the performance of electronic products. Traditional PCB connection methods include pulsed thermoforming (hotbar) bonding. During fabrication, holes need to be drilled in the PCB substrate, and copper is electroplated onto the ends and walls of the holes; the electroplated copper at the ends of the holes forms conductive pads. When connecting another PCB, conductive paste is first printed onto the conductive pads. After reflow soldering, the conductive paste melts and pre-solders onto the conductive pads. Then, the PCBs to be connected are placed on top of the conductive paste and pressed together using a hot bar. The holes are used to accommodate some of the conductive paste during hot bar bonding, preventing it from overflowing between the two conductive pads and causing a short circuit.

[0003] However, because it requires drilling holes and electroplating copper on the hole walls, the final hole diameter is difficult to control, and the hole walls are not smooth, which is not conducive to the smooth entry of conductive paste into the holes during hot pressing. Secondly, each circuit layer of the circuit board needs to be electrically connected to the conductive pad through a relatively thin copper hole wall, resulting in a small current-carrying cross-sectional area, which cannot meet the current-carrying requirements of large currents. Thirdly, the heat generated inside the circuit board is transferred layer by layer to the conductive pad through the circuit layers, insulating layers, and adhesive layers, and the mismatch of the thermal expansion coefficients of the interlayer materials leads to low heat dissipation efficiency. After long-term use, the heat concentration will affect the service life of the circuit board. Summary of the Invention

[0004] To address at least one of the above shortcomings, it is necessary to propose a circuit board and its fabrication method.

[0005] In addition, it is necessary to provide a circuit board connection structure having the above-mentioned circuit board.

[0006] This application provides a circuit board, including a circuit substrate. The circuit substrate includes at least one circuit layer. The circuit board further includes a plurality of conductive pads and an insulating layer. The thickness direction of the circuit substrate is defined as a first direction. The circuit substrate has a through-groove extending through the circuit substrate along the first direction. The conductive pads are disposed within the through-groove and electrically connected to the circuit layer. Each conductive pad has an opening along the first direction. The insulating layer is disposed within the through-groove and fills the gap between adjacent conductive pads.

[0007] In some possible implementations, the plurality of conductive pads includes a first group of conductive pads and a second group of conductive pads. A second direction and a third direction are defined as perpendicular to the first direction, and the second direction is perpendicular to the third direction. Along the second direction, the first group of conductive pads and the second group of conductive pads are spaced apart. Along the third direction, the plurality of conductive pads included in the first group of conductive pads are spaced apart, and the plurality of conductive pads included in the second group of conductive pads are also spaced apart. The plurality of conductive pads included in the first group of conductive pads and the plurality of conductive pads included in the second group of conductive pads are offset from each other along the second direction.

[0008] In some possible implementations, the openings of two adjacent conductive pads in the first group of conductive pads are staggered along the third direction, and the openings of two adjacent conductive pads in the second group of conductive pads are also staggered along the third direction.

[0009] In some possible implementations, the openings of two conductive pads in the first group of conductive pads, which are spaced apart by one conductive pad, are aligned along the third direction, and the openings of two conductive pads in the second group of conductive pads, which are spaced apart by one conductive pad, are aligned along the third direction.

[0010] In some possible implementations, the opening extends through the conductive pad along a first direction.

[0011] In some possible implementations, the insulating layer includes a third surface and a fourth surface disposed opposite to each other along the first direction. The conductive pad protrudes along the first direction from at least one of the third surface and the fourth surface.

[0012] A second aspect of this application provides a method for fabricating a circuit board, comprising: providing a circuit substrate, the circuit substrate including at least one circuit layer; forming a through-groove in the circuit substrate along a first direction, the first direction being the thickness direction of the circuit substrate; filling the through-groove with conductive blocks electrically connected to the circuit layer; covering a portion of the conductive blocks with a dry film; etching the conductive blocks exposed in the dry film by an exposure and development method to obtain a plurality of conductive pads, each of the conductive pads having an opening along the first direction, and then removing the dry film; and filling the through-groove with an insulating material such that the insulating material also fills the gaps between adjacent conductive pads, and curing to obtain an insulating layer.

[0013] In some possible implementations, the conductive block is formed by electroplating copper.

[0014] In some possible implementations, the plurality of conductive pads includes a first group of conductive pads and a second group of conductive pads. A third direction is defined perpendicular to the first direction, and the openings of adjacent conductive pads in the first group are staggered along the third direction, as are the openings of adjacent conductive pads in the second group.

[0015] A third aspect of this application also provides a circuit board connection structure, including a component to be connected and a circuit board as described above. The component to be connected is mounted to the conductive pad of the circuit board using conductive paste.

[0016] The conductive pads and their openings in this application are manufactured using an exposure and development process, making it easier to control the aperture diameter and ensuring a smoother inner wall for the conductive paste to enter smoothly and prevent short circuits. Secondly, the circuit layer in this application does not require a thin copper hole wall to electrically connect with the conductive pad, resulting in a larger cross-sectional area for the entire conductive loop, which can meet the current-carrying requirements of high currents. Thirdly, the heat generated inside the circuit board can be directly transferred to the conductive pad and dissipated to the outside, thus facilitating heat dissipation and preventing heat accumulation on the conductive pad after prolonged use, which could affect the lifespan of the circuit board. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of a copper-clad substrate provided in one embodiment of this application.

[0018] Figure 2 For etching Figure 1 The copper-clad substrate shown is a cross-sectional view after obtaining the first circuit layer.

[0019] Figure 3 For etching Figure 2 The cross-sectional view shown is of a copper-clad substrate after the second circuit layer has been obtained and the conductive portion has been formed.

[0020] Figure 4 In order to be in Figure 3 The cross-sectional view shown is of the second circuit layer after the insulating layer and copper foil layer have been laminated.

[0021] Figure 5 In order to be in Figure 4 The diagram shows a cross-sectional view of the circuit board after a through-slot has been created.

[0022] Figure 6 In order to be in Figure 5 The cross-sectional view shown is of the conductive block after electroplating inside the through-slot.

[0023] Figure 7 for Figure 6 A top view of the conductive block shown.

[0024] Figure 8 In order to be in Figure 7 A top view of the conductive block after it has been covered with a dry film.

[0025] Figure 9 For etching Figure 8 A top view of the conductive pad obtained after the conductive block is shown.

[0026] Figure 10 In order to be in Figure 9 The top view shown is of the conductive pad after it has been filled with insulating material.

[0027] Figure 11 for Figure 10 A cross-sectional view of the circuit board after filling with insulating material (the structure in the through slot is...). Figure 10 (Cross-sectional view along the XI-XI direction).

[0028] Figure 12 This is a cross-sectional view of a circuit board connection structure provided in one embodiment of this application.

[0029] Explanation of main component symbols

[0030] Circuit board 1

[0031] First copper-clad substrate 10

[0032] First copper foil layer 11

[0033] Second copper foil layer 12

[0034] First insulating layer 13

[0035] First Line Layer 14

[0036] Second line layer 15

[0037] Second copper-clad substrate 20

[0038] Second insulating layer 21

[0039] Third line layer 22

[0040] Adhesive layer 30

[0041] Conductive block 40

[0042] First surface 41

[0043] Second surface 42

[0044] Conductive pad 43

[0045] Dry film 50

[0046] Pattern 51

[0047] Third insulating layer 60

[0048] Third surface 61

[0049] Fourth surface 62

[0050] Circuit Board 100

[0051] Through slot 101

[0052] Blind hole 120

[0053] Conductor 121

[0054] Circuit board connection structure 200

[0055] Item to be connected 201

[0056] 430mm opening

[0057] First set of conductive pads 431

[0058] Second set of conductive pads 432

[0059] Pattern opening 510

[0060] First direction X

[0061] Second direction Y

[0062] Third direction Z

[0063] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0064] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0065] 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 this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0066] This application provides a method for fabricating a circuit board according to one embodiment. Depending on different requirements, the order of steps in the fabrication method can be changed, and some steps can be omitted or combined. The method includes the following steps:

[0067] Step S1, please refer to Figure 1 A first copper-clad substrate 10 is provided. The first copper-clad substrate 10 includes a first copper foil layer 11, a first insulating layer 13 and a second copper foil layer 12 sequentially stacked along a first direction X.

[0068] In some embodiments, the first insulating layer 13 is made of insulating resin, specifically at least one of polyimide (PI), liquid crystalline polymer (LCP), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN).

[0069] For step S2, please refer to [link / reference]. Figure 2 The first copper foil layer 11 is etched to obtain the first circuit layer 14.

[0070] In some embodiments, the first copper foil layer 11 can be etched by exposure and development.

[0071] Step S3, please refer to Figure 3 At least one blind via 120 is formed in the second copper foil layer 12. The blind via 120 penetrates the second copper foil layer 12 and the first insulating layer 13, and the first circuit layer 14 forms the bottom of the blind via 120. Then, a copper plating layer (not shown) is formed on the second copper foil layer 12, and the copper plating layer and the second copper foil layer 12 are etched to obtain the second circuit layer 15. A portion of the copper plating layer is also provided within each blind via 120 to form a conductive portion 121 for electrically connecting the second circuit layer 15 to the first circuit layer 14.

[0072] In some embodiments, blind holes 120 can be formed by mechanical drilling or laser drilling.

[0073] In some embodiments, a copper plating layer can be formed by electroplating copper. The conductive portion 121 can be formed on the inner wall of the blind via 120, or completely fill the blind via 120.

[0074] For step S4, please refer to [link / reference]. Figure 4 A second copper-clad substrate 20 is laminated onto the second circuit layer 15. The second copper-clad substrate 20 includes a second insulating layer 21 and a third copper foil layer (not shown), with the second insulating layer 21 located between the third copper foil layer and the second copper foil layer 12. Then, the third copper foil layer is etched to obtain the third circuit layer 22. At this point, the circuit substrate 1 is obtained. The thickness direction of the circuit substrate 1 is the first direction X.

[0075] In some embodiments, the second insulating layer 21 is made of insulating resin, specifically at least one of polyimide (PI), liquid crystalline polymer (LCP), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). The first insulating layer 13 and the second insulating layer 21 may be made of the same or different materials.

[0076] In some embodiments, an adhesive layer 30 may also be provided between the second insulating layer 21 and the second copper foil layer 12 to improve the interlayer bonding strength. The adhesive layer 30 may be made of ordinary pure adhesive, and this application is not limited thereto.

[0077] In some embodiments, the circuit board 1 includes three circuit layers. However, in other embodiments, the number of circuit layers included in the circuit board 1 can be varied.

[0078] Step S5, please refer to Figure 5 A through slot 101 is formed in the circuit board 1, and the through slot 101 penetrates the first circuit layer 14, the first insulating layer 13, the second circuit layer 15, the second insulating layer 21 and the third circuit layer 22.

[0079] In some embodiments, the through groove 101 can be formed by a scooping process.

[0080] For step S6, please refer to [link / reference]. Figure 6 and Figure 7 Conductive blocks 40 are filled in the through slot 101, and the conductive blocks 40 are electrically connected to the first circuit layer 14, the second circuit layer 15 and the third circuit layer 22.

[0081] In some embodiments, the conductive block 40 can be formed by electroplating copper. The conductive block 40 includes a first surface 41 and a second surface 42 disposed opposite to each other along a first direction X. The first surface 41 may be flush with the outer surface of the first circuit layer 14, and the second surface 42 may be flush with the outer surface of the third circuit layer 22.

[0082] For step S7, please refer to [link / reference]. Figure 8 A dry film 50 is applied to either the first surface 41 or the second surface 42. The dry film 50 has a plurality of patterns 51 corresponding to the conductive pads 43 to be formed (see step S8), and each pattern 51 has a pattern opening 510 corresponding to the required openings 430 in the conductive pads 43 (see step S8). A portion of the conductive blocks 40 are exposed from the dry film 50.

[0083] Step S8, please refer to Figure 9The conductive blocks 40 exposed on the dry film 50 are etched by exposure and development to obtain multiple conductive pads 43. Then, the dry film 50 is removed.

[0084] In some embodiments, the plurality of conductive pads 43 include a first group of conductive pads 431 and a second group of conductive pads 432. The first group of conductive pads 431 is electrically connected to the first circuit layer 14, the second circuit layer 15, and the third circuit layer 22, and the second group of conductive pads 432 is also electrically connected to the first circuit layer 14, the second circuit layer 15, and the third circuit layer 22. A second direction Y and a third direction Z are defined to be perpendicular to the first direction X, and the second direction Y is perpendicular to the third direction Z. Along the second direction Y, the first group of conductive pads 431 and the second group of conductive pads 432 are spaced apart. After exposure, development, and etching, along the third direction Z, the plurality of conductive pads 43 included in the first group of conductive pads 431 are spaced apart, and the plurality of conductive pads 43 included in the second group of conductive pads 432 are also spaced apart. The plurality of conductive pads 43 included in the first group of conductive pads 431 and the plurality of conductive pads 432 included in the second group of conductive pads 432 are offset from each other along the second direction Y.

[0085] After exposure, development, and etching, each conductive pad 43 is further provided with an opening 430 along the first direction X. Subsequently, when conductive paste (such as solder paste) needs to be applied to the conductive pad 43 and hot-pressed to install the object to be connected, the opening 430 is used to accommodate the overflowing conductive paste, preventing short circuits caused by contact between the conductive pads 43 due to the overflowing conductive paste. In some specific embodiments, the opening 430 can penetrate the conductive pad 43 along the first direction X. Compared with the prior art, the conductive pads 43 and the openings of the conductive pads 43 in this application are both made by exposure and development, making it easier to control the aperture of the opening 430, and the inner wall of the opening 430 is smoother, which is conducive to the smooth entry of conductive paste into the opening 430 to prevent short circuit problems. Secondly, the circuit layer of this application does not need to be electrically connected to the conductive pad 43 through a thin copper hole wall, so the cross-sectional area of ​​the entire conductive loop is larger, which can meet the current carrying requirements of large currents. Furthermore, the heat generated inside the circuit board 1 of this application can be directly transferred to the conductive pad 43 and dissipated to the outside by the conductive pad 43, thus facilitating heat dissipation and preventing heat accumulation on the conductive pad 43 after prolonged use, which would affect the product's lifespan. Finally, the conductive pad 43 of this application has greater overall rigidity, enabling the product to maintain good transmission performance when subjected to external forces.

[0086] In some embodiments, when viewed from the first direction X, the openings 430 of adjacent conductive pads 43 in the first group of conductive pads 431 are staggered along the third direction Z, and the openings 430 of adjacent conductive pads 432 in the second group of conductive pads are also staggered along the third direction Z. Thus, when the spacing between the conductive pads 43 along the third direction Z decreases, the problem of increased drilling difficulty caused by aligning all the openings 430 of each conductive pad 43 along the third direction Z can be avoided. Furthermore, this also helps to increase the drilling density on the conductive pads 43.

[0087] Furthermore, in the first group of conductive pads 431, the openings 430 of the two conductive pads 43 spaced apart by one conductive pad 43 are aligned along the third direction Z. In the second group of conductive pads 432, the openings 430 of the two conductive pads 43 spaced apart by one conductive pad 43 are aligned along the third direction Z.

[0088] For step S9, please refer to [link / reference]. Figure 10 and Figure 11 Insulating material is filled into the through groove 101, so that the insulating material also fills the gap between adjacent conductive pads 43, and after curing, a third insulating layer 60 is obtained.

[0089] In some embodiments, the filling insulating material may be insulating resin or ink.

[0090] In some embodiments, such as Figure 11 As shown, the third insulating layer 60 includes a third surface 61 and a fourth surface 62 disposed opposite to each other along the first direction X. A conductive pad 43 protrudes from the third surface 61 along the first direction X. This facilitates the mounting of an object to be connected onto the conductive pad 43 and the establishment of an electrical connection when it is necessary to mount the object on the third surface 61 side. It is understood that since the conductive pad 43 only has a height difference with the third insulating layer 60, while there may be no height difference between the conductive pad 43 and the circuit board 1, the problem of voids in the conductive paste can be reduced when conductive paste is applied to the conductive pad 43. Furthermore, the conductive pad 43 may also protrude from the fourth surface 62, facilitating the mounting of the object to be connected onto the conductive pad 43 from the fourth surface 62 side and the establishment of an electrical connection.

[0091] Please see Figure 11 One embodiment of this application also provides a circuit board 100, including a circuit board 1, a third insulating layer 60 and a plurality of conductive pads 43.

[0092] In some embodiments, the circuit board 1 includes a first circuit layer 14, a first insulating layer 13, a second circuit layer 15, an adhesive layer 30, a second insulating layer 21, and a third circuit layer 22, which are sequentially stacked along a first direction X. A through-groove 101 is formed in the circuit board 1, penetrating the first circuit layer 14, the first insulating layer 13, the second circuit layer 15, the adhesive layer 30, the second insulating layer 21, and the third circuit layer 22. The third insulating layer 60 is disposed within the through-groove 101, and a plurality of conductive pads 43 are disposed within the third insulating layer 60.

[0093] Please refer to the above as well. Figure 9 and Figure 10 In some embodiments, the plurality of conductive pads 43 includes a first group of conductive pads 431 and a second group of conductive pads 432. A second direction Y and a third direction Z are defined as perpendicular to the first direction X, and the second direction Y is perpendicular to the third direction Z. Along the second direction Y, the first group of conductive pads 431 and the second group of conductive pads 432 are spaced apart. Along the third direction Z, the plurality of conductive pads 43 included in the first group of conductive pads 431 are spaced apart, and the plurality of conductive pads 43 included in the second group of conductive pads 432 are also spaced apart. The plurality of conductive pads 43 included in the first group of conductive pads 431 and the plurality of conductive pads 43 included in the second group of conductive pads 432 are offset from each other along the second direction Y.

[0094] In some embodiments, each conductive pad 43 is further provided with an opening 430 along the first direction X. In some specific embodiments, the opening 430 may penetrate the conductive pad 43 along the first direction X.

[0095] Furthermore, when viewed from the first direction X, the openings 430 of adjacent conductive pads 43 in the first group of conductive pads 431 are staggered along the third direction Z, and the openings 430 of adjacent conductive pads 43 in the second group of conductive pads 432 are also staggered along the third direction Z. More specifically, the openings 430 of two conductive pads 43 in the first group of conductive pads 431, which are spaced apart by one conductive pad 43, are aligned along the third direction Z, and the openings 430 of two conductive pads 43 in the second group of conductive pads 432, which are spaced apart by one conductive pad 43, are aligned along the third direction Z.

[0096] like Figure 11 As shown, in some embodiments, the third insulating layer 60 includes a third surface 61 and a fourth surface 62 disposed opposite to each other along a first direction X. A conductive pad 43 protrudes from at least one of the third surface 61 and the fourth surface 62 along the first direction X.

[0097] Please see Figure 12One embodiment of this application also provides a circuit board connection structure 200, including a circuit board 100 and an object to be connected 201. The conductive pad 43 of the circuit board 100 is provided with conductive paste 202, and the object to be connected 201 is mounted on the conductive pad 43 through the conductive paste 202, thereby electrically connecting to the circuit board 100.

[0098] In some embodiments, the conductive paste 202 may specifically be solder paste. The circuit board 100 may be a printed circuit board, and the object to be connected 201 may be a flexible circuit board.

[0099] Furthermore, those skilled in the art can make various other corresponding changes and modifications based on the technical concept of this application, and all such changes and modifications should fall within the protection scope of this application.

Claims

1. A circuit board, comprising a circuit substrate, the circuit substrate including at least one circuit layer, characterized in that, The circuit board also includes: Multiple conductive pads are provided, defining the thickness direction of the circuit board as a first direction. The circuit board has a through-groove extending along the first direction. The conductive pads are disposed within the through-groove and electrically connected to the circuit layer. Each conductive pad has an opening along the first direction. An insulating layer is disposed within the through groove and fills the gap between adjacent conductive pads.

2. The circuit board as described in claim 1, characterized in that, The plurality of conductive pads include a first group of conductive pads and a second group of conductive pads. A second direction and a third direction are defined to be perpendicular to the first direction and the second direction is perpendicular to the third direction. Along the second direction, the first group of conductive pads and the second group of conductive pads are spaced apart. Along the third direction, the plurality of conductive pads included in the first group of conductive pads are spaced apart, and the plurality of conductive pads included in the second group of conductive pads are also spaced apart. The plurality of conductive pads included in the first group of conductive pads and the plurality of conductive pads included in the second group of conductive pads are staggered from each other along the second direction.

3. The circuit board as described in claim 2, characterized in that, In the first group of conductive pads, the openings of two adjacent conductive pads are staggered along the third direction, and in the second group of conductive pads, the openings of two adjacent conductive pads are also staggered along the third direction.

4. The circuit board as described in claim 3, characterized in that, In the first group of conductive pads, the openings of two conductive pads spaced apart by one conductive pad are aligned along the third direction. In the second group of conductive pads, the openings of two conductive pads spaced apart by one conductive pad are aligned along the third direction.

5. The circuit board as described in claim 1, characterized in that, The opening extends through the conductive pad along the first direction.

6. The circuit board as described in claim 1, characterized in that, The insulating layer includes a third surface and a fourth surface disposed opposite to each other along the first direction, and the conductive pad protrudes from at least one of the third surface and the fourth surface along the first direction.

7. A method for manufacturing a circuit board, characterized in that, include: A circuit board is provided, the circuit board comprising at least one circuit layer; A through slot is formed in the circuit substrate along a first direction, wherein the first direction is the thickness direction of the circuit substrate. The through slot is filled with conductive blocks, which are electrically connected to the circuit layer; A dry film is coated on a portion of the conductive blocks; The conductive blocks exposed on the dry film are etched by exposure and development to obtain a plurality of conductive pads, each of which has an opening along a first direction, and then the dry film is removed. as well as An insulating material is filled into the through groove, such that the insulating material also fills the gap between adjacent conductive pads, and an insulating layer is obtained after curing.

8. The method for preparing a circuit board as described in claim 7, characterized in that, The conductive block is formed by electroplating copper.

9. The method for preparing a circuit board as described in claim 7, characterized in that, The plurality of conductive pads include a first group of conductive pads and a second group of conductive pads, with a third direction defined perpendicular to the first direction. The openings of two adjacent conductive pads in the first group of conductive pads are staggered along the third direction, and the openings of two adjacent conductive pads in the second group of conductive pads are also staggered along the third direction.

10. A circuit board connection structure, comprising objects to be connected, characterized in that, The circuit board connection structure further includes a circuit board as described in any one of claims 1 to 6, wherein the object to be connected is mounted on the conductive pad of the circuit board using conductive paste.

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