Circuit board manufacturing method and circuit board

Abstract

The invention relates to the technical field of circuit board manufacturing, and provides a circuit board manufacturing method and a circuit board, and the circuit board manufacturing method comprises the steps: providing a first sub-board, a connecting board and a second sub-board; an anti-oxidation layer is arranged on the surface of the first bonding pad of the first sub-board and / or the surface of the second bonding pad of the second sub-board; through holes are formed in the positions, corresponding to the first bonding pad of the first daughter board and the second bonding pad of the second daughter board, of the connecting board, and the through holes are filled with conducting media; and the first daughter board, the connecting board and the second daughter board are stacked and laminated in sequence, so that the first bonding pad of the first daughter board and the second bonding pad of the second daughter board are electrically conducted through the conductive medium. According to the circuit board manufacturing method, the anti-oxidation layer is used for protecting the surface of the bonding pad, so that the surface of the bonding pad is not easy to oxidize, the surface of the bonding pad and the conducting medium form an IMC layer, the binding force of the surface of the bonding pad and the conducting medium is improved, and the interconnection reliability of the circuit board adopting the Z-direction interconnection technology is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit board manufacturing, in particular to a circuit board manufacturing method and a circuit board. BACKGROUND

[0002] Z-direction interconnection of circuit boards refers to electrical interconnection between circuit boards through connection in the vertical direction. The circuit boards using Z-direction interconnection technology can simplify the manufacturing process, and realize interconnection and conduction between sub-boards without the need for drilling, hole metallization, resin hole plugging and other operations. It is particularly suitable for electronic devices requiring high integration and high performance, such as high-performance computing, communication devices, industrial control and other fields.

[0003] In actual production, a circuit board with a high number of layers is usually divided into at least two sub-boards, and the manufacturing of each sub-board is completed respectively. Then, a conductive medium is arranged at the pads between the sub-boards to realize interconnection and conduction. However, the bonding force between the conductive medium and the pad in the prior art is poor, resulting in poor interconnection reliability. SUMMARY

[0004] Therefore, the present application provides a circuit board manufacturing method and a circuit board to solve the problem of poor interconnection reliability of circuit boards using Z-direction interconnection technology.

[0005] A first aspect of the present application provides a circuit board manufacturing method, comprising:

[0006] providing a first sub-board, a connecting plate and a second sub-board;

[0007] providing an oxidation-resistant layer on the surface of the first pad of the first sub-board and / or the second pad of the second sub-board;

[0008] opening a through hole on the connecting plate corresponding to the position of the first pad of the first sub-board and the second pad of the second sub-board, and filling the through hole with a conductive medium;

[0009] stacking and pressing the first sub-board, the connecting plate and the second sub-board in sequence, so that the first pad of the first sub-board and the second pad of the second sub-board are electrically connected through the conductive medium.

[0010] The circuit board manufacturing method provided by the present application has the following beneficial effects: by providing an oxidation-resistant layer on the surface of the first pad and / or the second pad, the surface of the pad is protected by the oxidation-resistant layer, so that the surface of the pad is not easily oxidized, which facilitates the formation of an IMC (Intermetallic Compound) layer between the surface of the pad and the conductive medium, improves the bonding force between the surface of the pad and the conductive medium, and thus improves the interconnection reliability of the circuit board using Z-direction interconnection technology.

[0011] In some embodiments, the anti-oxidation layer is a metal layer.

[0012] In some embodiments, the metal layer is a gold layer, a nickel-gold layer, a silver layer, or a tin layer.

[0013] In some embodiments, an anti-oxidation layer is arranged on the surface of the second pad of the second sub-board; before the first sub-board, the connecting board, and the second sub-board are sequentially stacked and pressed, the first sub-board and the connecting board are pre-bonded.

[0014] In some embodiments, after the first sub-board and the connecting board are pre-bonded, the residue glue at the bottom of the through hole and / or the copper oxide layer on the first pad of the first sub-board is removed.

[0015] In some embodiments, before the through hole is filled with the conductive medium, a first protective film is attached to the side of the connecting board away from the first sub-board, and the first protective film is provided with a first window corresponding to the position of the through hole; when the through hole is filled with the conductive medium, the conductive medium enters the through hole of the connecting board through the first window; after the through hole is filled with the conductive medium, the first protective film is removed.

[0016] In some embodiments, the conductive medium is formed by drying and sintering of pure metal conductive paste; or, the conductive medium is formed by drying and sintering of alloy conductive paste; or, the conductive medium is formed by drying and sintering of carbon-based conductive paste; or, the conductive medium is formed by drying and sintering of composite conductive paste.

[0017] In some embodiments, when the surface of the pad of the corresponding sub-board is arranged with an anti-oxidation layer, the surface of the pad is first protected by an anti-plating medium protective plate and exposed, and then the pad is subjected to anti-oxidation treatment.

[0018] In some embodiments, the connecting board is a prepreg.

[0019] The second aspect of the present application provides a circuit board, which is made by the circuit board manufacturing method as described in the first aspect.

[0020] The circuit board adopts any one or more embodiments of the above-mentioned circuit board manufacturing method, and thus has the beneficial effects of the above-mentioned embodiments, which will not be repeated here.

[0021] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the circuit board manufacturing method can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the conventional technologies will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0023] Figure 1 is a flowchart of a circuit board manufacturing method provided by some embodiments of the present application;

[0024] Figure 2 is a structural schematic diagram of a first sub-board, a connecting board and a second sub-board provided by some embodiments of the present application;

[0025] Figure 3 is Figure 2 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the second pad of the second sub-board being provided with an oxidation-resistant layer;

[0026] Figure 4 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the through hole being filled with a conductive medium;

[0027] Figure 5 is Figure 4 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the through hole being filled with a conductive medium;

[0028] Figure 6 is Figure 5 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the through hole being filled with a conductive medium;

[0029] Figure 7 is Figure 6 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the through hole being filled with a conductive medium;

[0030] Figure 8 is Figure 2 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the through hole being filled with a conductive medium;

[0031] Figure 9 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the through hole being filled with a conductive medium;

[0032] Figure 10 is Figure 9 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the through hole being filled with a conductive medium;

[0033] Figure 11 is Figure 10 is a structural schematic diagram of the first sub-board and the connecting board pre-bonding, and the through hole being filled with a conductive medium.

[0034] The meanings of the marks in the figures are as follows:

[0035] 10, first sub-board; 11, first pad;

[0036] 20, second sub-board; 21, second pad;

[0037] 30, connecting plate; 31, through hole;

[0038] 40, antioxidant layer;

[0039] 50, conductive medium;

[0040] 60, first protective film; 61, first window;

[0041] 70, second protective film;

[0042] 80, third protective film; 81, second window. DETAILED DESCRIPTION

[0043] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0044] 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 terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0045] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0046] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0047] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0048] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0049] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0050] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanical connection, or it can be electrical connection; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0051] The embodiments of the first aspect of the present application propose a circuit board manufacturing method. Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 8 , the circuit board manufacturing method comprises:

[0052] S1, providing a first sub-board 10, a connecting plate 30 and a second sub-board 20.

[0053] The first sub-board 10 needs to at least complete the manufacturing of the circuit layer on the side where the first pad 11 is located; it can be understood that the first sub-board 10 can be a single-sided circuit board, a double-sided circuit board or a multi-layer circuit board.

[0054] The second sub-board 20 needs to at least complete the manufacturing of the circuit layer on the side where the second pad 21 is located; it can be understood that the second sub-board 20 can be a single-sided circuit board, a double-sided circuit board or a multi-layer circuit board.

[0055] The single-sided circuit board refers to that the circuit is arranged on one side of the circuit board; the double-sided circuit board refers to that the circuit is arranged on both sides of the circuit board; and the multi-layer circuit board refers to that the circuit is arranged on both sides of the circuit board and in the interior of the circuit board.

[0056] S2, an oxidation-resistant layer 40 is arranged on the surface of the first pad 11 of the first sub-circuit board 10 and / or the second pad 21 of the second sub-circuit board 20.

[0057] It can be understood that the oxidation-resistant layer 40 can be arranged on the surface of the first pad 11 of the first sub-circuit board 10 and the second pad 21 of the second sub-circuit board 20; or the oxidation-resistant layer 40 can be arranged on the surface of the first pad 11 of the first sub-circuit board 10, and the surface of the second pad 21 of the second sub-circuit board 20 is not provided with the oxidation-resistant layer 40, for example, the second sub-circuit board 20 is first pre-bonded with the connecting plate 30; or the oxidation-resistant layer 40 can be arranged on the surface of the second pad 21 of the second sub-circuit board 20, and the surface of the first pad 11 of the first sub-circuit board 10 is not provided with the oxidation-resistant layer 40, for example, the first sub-circuit board 10 is first pre-bonded with the connecting plate 30.

[0058] Optionally, the first pad 11 and the second pad 21 are copper pads.

[0059] S3, a through hole 31 is arranged on the connecting plate 30 corresponding to the positions of the first pad 11 of the first sub-circuit board 10 and the second pad 21 of the second sub-circuit board 20, and a conductive medium 50 is filled in the through hole 31.

[0060] It can be understood that the through hole 31 communicates both sides of the connecting plate 30 in the thickness direction.

[0061] Since the through hole 31 is arranged corresponding to the positions of the first pad 11 of the first sub-circuit board 10 and the second pad 21 of the second sub-circuit board 20, that is, after the first sub-circuit board 10, the connecting plate 30 and the second sub-circuit board 20 are pressed together, the conductive medium 50 filled in the through hole 31 connects and conducts the first pad 11 and the second pad 21, so as to realize the interconnection of the first sub-circuit board 10 and the second sub-circuit board 20.

[0062] The connecting plate 30 plays a role of bonding the first sub-circuit board 10 and the second sub-circuit board 20 when being pressed. The connecting plate 30 is made of insulating material, that is, after the first sub-circuit board 10, the connecting plate 30 and the second sub-circuit board 20 are pressed together, the connecting plate 30 is used to insulate and separate the first sub-circuit board 10 and the second sub-circuit board 20, and only the conductive medium 50 on the connecting plate 30 is used to conduct the first sub-circuit board 10 and the second sub-circuit board 20.

[0063] S4, the first sub-circuit board 10, the connecting plate 30 and the second sub-circuit board 20 are sequentially stacked and pressed together, so that the first pad 11 of the first sub-circuit board 10 and the second pad 21 of the second sub-circuit board 20 are electrically conducted through the conductive medium 50.

[0064] The first sub-board 10, the connecting board 30 and the second sub-board 20 are sequentially stacked and pressed, that is, the connecting board 30 is between the first sub-board 10 and the second sub-board 20; wherein the first pad 11 is arranged on a side of the first sub-board 10 facing the connecting board 30, and the second pad 21 is arranged on a side of the second sub-board 20 facing the connecting board 30.

[0065] The circuit board manufacturing method provided by the embodiment has the beneficial effect that: since the key point of the Z-direction interconnection technology is that the conductive medium 50 and the pad surface can form an IMC layer, if the pad surface has an oxidation layer, the IMC layer cannot be formed, which leads to Z-direction interconnection failure. The anti-oxidation layer 40 is arranged on the surface of the first pad 11 and / or the second pad 21 to protect the pad surface by the anti-oxidation layer 40, so that the pad surface is not easily oxidized, which facilitates the formation of the IMC layer between the pad surface and the conductive medium 50, improves the bonding force between the pad surface and the conductive medium 50, and thus improves the interconnection reliability of the circuit board using the Z-direction interconnection technology.

[0066] In some embodiments, the anti-oxidation layer 40 is a metal layer. When the first sub-board 10, the connecting board 30 and the second sub-board 20 are pressed, the anti-oxidation layer 40 participates in the formation of the IMC layer, further improving the bonding force between the pad surface and the conductive medium 50.

[0067] It can be understood that the metal layer can be a gold layer, which can be realized by a gold plating process; or the metal layer can be a silver layer, which can be realized by a silver plating process; or the metal layer can be a tin layer, which can be realized by a tin plating process; or the metal layer can be a nickel-gold layer.

[0068] In other embodiments, the anti-oxidation layer 40 can be an organic layer, for example, an OSP (Organic Solderability Preservative, organic solderability preservative layer); when the first sub-board 10, the connecting board 30 and the second sub-board 20 are pressed, the OSP is decomposed by heat and does not participate in the formation of the IMC layer.

[0069] Please refer to Figure 3 In some embodiments, the anti-oxidation layer 40 is arranged on the surface of the second pad 21 of the second sub-board 20; before the first sub-board 10, the connecting board 30 and the second sub-board 20 are sequentially stacked and pressed, the first sub-board 10 and the connecting board 30 are first pre-bonded.

[0070] It can be understood that the through hole 31 can be formed on the connecting board 30 before the first sub-board 10 and the connecting board 30 are pre-bonded; or the through hole 31 can be formed on the connecting board 30 after the first sub-board 10 and the connecting board 30 are pre-bonded.

[0071] For example, after the first sub-board 10 and the connecting board 30 are pre-bonded, a through hole 31 is formed on the connecting board 30 by mechanical processing or laser ablation. The conductive medium 50 is filled in the through hole 31 by screen printing, inkjet printing, or dispensing. The conductive medium 50 is pre-dried to achieve a preliminary solidification state after the solvent is volatilized. Then, the second sub-board 20 is stacked, and high-temperature compression and sintering are performed to form a Z-direction interconnected circuit board.

[0072] According to the above technical solution, since the first sub-board 10 and the connecting board 30 are pre-bonded, it is not necessary to provide an oxidation-resistant layer 40 on the surface of the first pad 11 of the first sub-board 10, thereby simplifying the steps and improving the manufacturing efficiency of the circuit board.

[0073] For example, after the first sub-board 10 and the connecting board 30 are pre-bonded, a through hole 31 is formed on the connecting board 30 by mechanical processing or laser ablation. The conductive medium 50 is filled in the through hole 31 by screen printing, inkjet printing, or dispensing. The conductive medium 50 is pre-dried to achieve a preliminary solidification state after the solvent is volatilized. Then, the second sub-board 20 is stacked, and high-temperature compression and sintering are performed to form a Z-direction interconnected circuit board. Figure 4 It can be understood that when there is residual glue at the bottom of the through hole 31, the residual glue at the bottom of the through hole 31 is removed; when there is a copper oxide layer on the first pad 11, the copper oxide layer on the first pad 11 is removed; and when there is residual glue at the bottom of the through hole 31 and a copper oxide layer on the first pad 11, the residual glue at the bottom of the through hole 31 and the copper oxide layer on the first pad 11 are removed.

[0074] For example, a UV laser (i.e., a laser with a wavelength in the ultraviolet spectrum) can be used to process the bottom of the through hole 31 to remove the residual glue at the bottom of the through hole 31 and the copper oxide layer on the first pad 11.

[0075] The residual glue at the bottom of the through hole 31 is generated after the first sub-board 10 and the connecting board 30 are pre-bonded, and the copper oxide layer is generated by oxidation of the surface of the first pad 11.

[0076] According to the above technical solution, by removing the residual glue at the bottom of the through hole 31 and the copper oxide layer on the first pad 11, the bonding force between the conductive medium 50 and the first pad 11 can be improved.

[0077] In some embodiments, in the case where the first sub-board 10 and the connecting board 30 are pre-bonded, please refer to

[0078] Before the conductive medium 50 is filled in the through hole 31, a first protective film 60 is attached to the side of the connecting board 30 away from the first sub-board 10 to prevent the conductive medium 50 from overflowing to other places of the connecting board 30 during filling. The first protective film 60 has a first window 61 corresponding to the position of the through hole 31. Please refer to Figure 5 Figure 6 ​When filling the conductive medium 50 into the through hole 31, the conductive medium 50 enters the through hole 31 of the connecting plate 30 through the first window 61, for example, the conductive medium 50 is filled into the through hole 31 by printing. Please refer to Figure 7 After filling the conductive medium 50 into the through hole 31, the first protective film 60 is removed to avoid affecting the compression.

[0079] In some embodiments, the conductive medium 50 is formed by drying and sintering of the conductive paste.

[0080] Optionally, the conductive medium 50 is formed by drying and sintering of pure metal conductive paste, for example, pure metal conductive paste is copper paste, silver paste, etc., which has the ability of filling, conducting (after sintering) and heat dissipation. Among them, the copper paste is formed by combining metal copper with adhesive (also known as binder), and the microparticles of metal copper are dispersed in the adhesive, which can be filled into the specified position by printing and other methods; the silver paste is formed by combining metal silver with adhesive (also known as binder), and the microparticles of metal silver are dispersed in the adhesive, which can be filled into the specified position by printing and other methods. Among them, the binder usually adopts synthetic resin, such as phenolic resin, epoxy resin, etc.

[0081] Optionally, the conductive medium 50 is formed by drying and sintering of alloy conductive paste, for example, alloy conductive paste is copper-tin paste, silver-palladium paste, silver-copper paste, etc. Among them, the copper-tin paste is a paste composed of micron copper, tin alloy particles, solvent, flux, etc.

[0082] Optionally, the conductive medium 50 is formed by drying and sintering of carbon-based conductive paste, for example, graphene paste, carbon nanotube paste, etc.

[0083] Optionally, the conductive medium 50 is formed by drying and sintering of composite conductive paste, for example, metal-carbon composite paste, etc.

[0084] Regarding the interface between the conductive medium 50 and the solder pad after sintering, when the conductive paste is copper paste composed of pure copper powder, the copper paste and the solder pad (copper surface) form a dense copper connection body by diffusion of copper atoms during high-temperature sintering, instead of a heterogeneous IMC layer; when the conductive paste is not pure copper powder, that is, other metals participate in the reaction, a heterogeneous IMC layer is usually formed. Non-pure copper powder is often used to form conductive paste in production.

[0085] In some embodiments, when the oxidation-resistant layer 40 is arranged on the surface of the solder pad of the corresponding daughter board, the solder pad is first protected by the anti-plating medium and exposed, and then the solder pad is subjected to oxidation-resistant treatment, that is, the solder pad which needs to be in contact with the conductive medium 50 is exposed by protecting the surface of the solder pad by the anti-plating medium and other copper layers.

[0086] It can be understood that dry film / wet film, blue glue, high-temperature resistant adhesive tape, etc. can be used as the anti-plating medium.

[0087] When dry film / wet film is used, the specified pads can be exposed after the dry film is pasted / wet film is coated on the board surface, exposure, and development. When blue glue is used, the blue glue can be selectively printed on the board surface using a screen to expose the specified pads; or, to improve the coverage accuracy of the blue glue, the entire board can be printed using a screen, and then the unwanted parts can be removed by laser cutting to expose the specified pads. When high-temperature-resistant adhesive tape is used, the unwanted parts can be removed by laser cutting to expose the specified pads.

[0088] In some embodiments, the connecting plate 30 is a prepreg.

[0089] Before pressing, the connecting plate 30 is in a semi-cured state, and is converted to a cured state after the high-temperature and high-pressure conditions of the pressing process. The material of the prepreg generally includes resin and glass fiber cloth, and the resin can be epoxy resin, polyimide resin, polytetrafluoroethylene resin, polyphenyl ether resin, polyester resin, bismaleimide triazine resin, etc.

[0090] Please refer to Figure 8 In some embodiments, an oxidation-resistant layer 40 is arranged on the surfaces of the first pads 11 of the first sub-board 10 and the second pads 21 of the second sub-board 20, and then the first sub-board 10, the connecting plate 30, and the second sub-board 20 are sequentially stacked and pressed.

[0091] The manufacturing process of the connecting plate 30 in this embodiment is as follows: please refer to Figure 9 First, a through hole 31 for filling the conductive medium 50 is formed on the connecting plate 30; then, please refer to Figure 10 A second protective film 70 is arranged on one side of the connecting plate 30, a third protective film 80 is arranged on the other side of the connecting plate 30, and a second window 81 is arranged on the third protective film 80 corresponding to the position of the through hole 31. Then, please refer to Figure 11 The conductive paste is printed, the conductive paste enters the through hole 31 through the second window 81, and after the conductive paste is pre-dried, the second protective film 70 and the third protective film 80 are removed.

[0092] The specific process of the circuit board manufacturing method provided in the embodiments of the present application is as follows:

[0093] Prepare the first sub-board 10 and the second sub-board 20. In this embodiment, the first sub-board 10 and the second sub-board 20 are both multi-layer boards formed by at least one pressing, and the first sub-board 10 and the second sub-board 20 have both completed the inner layer circuit pattern and the circuit pattern on the side facing the connecting plate 30.

[0094] Prepare the connecting plate 30. In this embodiment, the connecting plate 30 is a prepreg of epoxy resin type, and the thickness is selected according to the actual situation.

[0095] Please refer toFigure 4 The connecting plate 30 is pre-bonded with the first sub-plate 10, which can be achieved by fast pressing. A through hole 31 is formed in the connecting plate 30 by using mechanical or laser processing, until the bottom of the through hole 31 exposes the first solder pad 11 of the first sub-plate 10. In this embodiment, laser ablation is used to form the through hole, and after laser ablation, UV laser is used to remove the glue layer at the bottom of the hole and ablate the copper oxide layer on the surface of the first solder pad 11.

[0096] Please refer to Figure 5 and Figure 6 The conductive paste is filled into the through hole 31 on the connecting plate 30 by screen printing and pre-dried to obtain the conductive medium 50. In this embodiment, the conductive paste is a copper-tin paste containing micron-sized copper and tin alloy particles. Before printing the copper-tin paste, a first protective film 60 is attached to the side of the connecting plate 30 away from the first sub-plate 10 to prevent the copper-tin paste from overflowing to other areas of the first sub-plate 10. Understandably, the first protective film 60 has a first window 61 corresponding to the through hole 31 on the connecting plate 30; or the first protective film 60 is attached before the through hole 31 is formed on the connecting plate 30, and the through hole 31 of the connecting plate 30 and the first window 61 on the first protective film 60 are processed together.

[0097] An anti-oxidation layer 40 is provided on the second solder pad 21 of the second sub-plate 20, for example, the anti-oxidation layer 40 is a gold plating layer. Specifically, a selected chemical ink is applied to the surface of the second sub-plate 20 where the second solder pad 21 is located, and after curing, a chemical corrosion resistant film layer is formed, and then gold plating is performed. At this time, the area covered by the selected chemical ink does not react with the gold plating solution, and only the exposed second solder pad 21 deposits a gold layer; finally, the selected chemical ink is removed by a deinking process to expose the protected non-gold plating area, and the anti-oxidation layer 40 is provided on the second solder pad 21 of the second sub-plate 20.

[0098] Please refer to Figure 7 and Figure 8 The first protective film 60 on the connecting plate 30 is removed, and the second sub-plate 20 is stacked on the side of the connecting plate 30 away from the first sub-plate 10, and high-temperature pressing is performed to bond the first sub-plate 10, the connecting plate 30, and the second sub-plate 20 into one body. The connecting plate 30 (prepreg) melts and flows to fill the bonding surface of the first sub-plate 10, the second sub-plate 20, and the connecting plate 30, and the conductive medium 50 in the connecting plate 30 is sintered under high temperature. Finally, a Z-directionally interconnected circuit board is obtained.

[0099] It should be noted that the above embodiments are described by taking the circuit board comprising two sub-boards (the first sub-board 10 and the second sub-board 20) as an example. In fact, the circuit board can further comprise more sub-boards, and the connecting plate 30 can be additionally provided according to the number of sub-boards to be bonded. For example, the circuit board further comprises a third sub-board, and the connecting plate 30 is provided with two connecting plates 30, one of which is arranged between the first sub-board 10 and the second sub-board 20, and the other of which is arranged between the second sub-board 20 and the third sub-board; or the circuit board further comprises a third sub-board and a fourth sub-board, and the connecting plate 30 is provided with three connecting plates 30, the first connecting plate 30 is arranged between the first sub-board 10 and the second sub-board 20, the second connecting plate 30 is arranged between the second sub-board 20 and the third sub-board, and the third connecting plate 30 is arranged between the third sub-board and the fourth sub-board. The electrical conduction between the adjacent two sub-boards can be achieved by the above method, and details are not described herein.

[0100] The second aspect of the present application provides a circuit board, which is made by the circuit board manufacturing method as described in the first aspect. The circuit board comprises a first sub-board 10, a second sub-board 20 and a connecting plate 30. The connecting plate 30 is arranged between the first sub-board 10 and the second sub-board 20, and the first sub-board 10 and the second sub-board 20 are respectively provided with a first pad 11 and a second pad 21 on the side facing the connecting plate 30; the connecting plate 30 is provided with a through hole 31, and the through hole 31 is provided with a conductive medium 50, and the first sub-board 10 and the second sub-board 20 are electrically connected through the conductive medium 50 on the connecting plate 30. Specifically, the first pad 11 of the first sub-board 10 and the second pad 21 of the second sub-board 20 are electrically connected through the conductive medium 50.

[0101] Among them, the surface of the first pad 11 of the first sub-board 10 and / or the second pad 21 of the second sub-board 20 before pressing is provided with an anti-oxidation layer 40, that is, the bonding surface of the pad and the conductive medium 50 is provided with an anti-oxidation layer 40. Under the high temperature condition during pressing, the contact interface between the pad and the conductive medium 50 forms an IMC layer. When the anti-oxidation layer 40 on the pad is a metal layer, the anti-oxidation layer 40 will participate in the formation of the IMC layer; when the anti-oxidation layer 40 is OSP, the OSP is decomposed by heat and does not participate in the formation of the IMC layer.

[0102] The circuit board adopts any one or more of the above embodiments of the circuit board manufacturing method, and thus has the beneficial effects of the above embodiments, which are not described herein.

[0103] The above examples are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method of manufacturing a circuit board, characterized by, The application relates to a circuit board and a manufacturing method thereof. The first sub-board, the connecting board and the second sub-board are sequentially stacked and pressed to make the first pads of the first sub-board and the second pads of the second sub-board electrically conductive through the conductive medium. The antioxidation layer is a metal layer. The metal layer is a gold layer, a nickel-gold layer, a silver layer or a tin layer. The surface of the second pads of the second sub-board is provided with an antioxidation layer; before the first sub-board, the connecting board and the second sub-board are sequentially stacked and pressed, the first sub-board is first pre-bonded with the connecting board.

2. The method of manufacturing a circuit board according to claim 1, wherein After the first sub-board and the connecting board are pre-bonded, the hole bottom residue of the through hole and / or the copper oxide layer on the first pads of the first sub-board are removed.

3. The method of manufacturing a circuit board according to claim 2, wherein Before the conductive medium is filled in the through hole, a first protective film is attached to the side of the connecting board away from the first sub-board, and the first protective film is provided with a first window corresponding to the position of the through hole; when the conductive medium is filled in the through hole, the conductive medium enters the through hole of the connecting board through the first window; after the conductive medium is filled in the through hole, the first protective film is removed.

4. The method of manufacturing a circuit board according to claim 1, wherein The conductive medium is formed by drying and sintering of pure metal conductive paste, alloy conductive paste, carbon-based conductive paste or composite conductive paste.

5. The method of manufacturing a circuit board according to claim 4, wherein When the surface of the pads of the corresponding sub-boards is provided with an antioxidation layer, the pad surface is first protected by an anti-plating medium protection plate and exposed, and then the pad is subjected to antioxidation treatment.

6. The method of manufacturing a circuit board according to claim 5, wherein The connecting board is a prepreg.

7. The method of manufacturing a circuit board according to any one of claims 1 to 6, wherein The circuit board is manufactured by the manufacturing method of any one of claims 1-9. ​ 8. The method of manufacturing a circuit board according to any one of claims 1 to 6, wherein ​ 9. The method of manufacturing a circuit board according to any one of claims 1 to 6, wherein ​ 10. A circuit board, characterized by ​

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