Circuit board, preparation method therefor, display module, and display apparatus

Abstract

A circuit board, a preparation method therefor, a display module, and a display apparatus. The circuit board comprises: a first circuit board unit, a first conductive layer, an adhesive layer, and a second circuit board unit, stacked in sequence; a first conductive connector, penetrating through the first circuit board unit; a second conductive connector, penetrating through the second circuit board unit and the bonding layer; and a third conductive connector, penetrating through the first conductive layer. The third conductive connector is separately connected to the first conductive connector and the second conductive connector. The bonding strength between the first conductive connector and the third conductive connector is greater than that between the first conductive connector and the first conductive layer, and the bonding strength between the second conductive connector and the third conductive connector is greater than that between the second conductive connector and the first conductive layer. Reliability is improved.

Description

Circuit board and manufacturing method thereof, display module and display device

[0001] This application claims priority to the Chinese patent application with application number 202311560535.X filed on November 21, 2023, and application name “A circuit board, a preparation method thereof, a display module and a display device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to a circuit board and a manufacturing method thereof, a display module and a display device. Background Art

[0003] Circuit boards include flexible circuit boards (FPCBs) or printed circuit boards (PCBs). PCBs enable electronic components to achieve predetermined electrical connections. FPCBs, also known as flexible printed circuits (FPCs), are made from flexible materials such as polyimide or polyester film, offering high reliability and flexibility. FPCBs or PCBs are often used to electrically connect to display panels to form display modules. Summary of the Invention

[0004] The present application provides a circuit board and a manufacturing method thereof, a display module and a display device.

[0005] In a first aspect, a circuit board is provided, comprising:

[0006] A first circuit board unit, a first conductive layer, an adhesive layer, and a second circuit board unit are sequentially stacked;

[0007] a first conductive connector passing through the first circuit board unit;

[0008] a second conductive connector passing through the second circuit board unit and the adhesive layer;

[0009] a third conductive connector penetrating the first conductive layer;

[0010] The third conductive connector is connected to the first conductive connector and the second conductive connector respectively, the bonding strength between the first conductive connector and the third conductive connector is greater than the bonding strength between the first conductive connector and the first conductive layer, and the bonding strength between the second conductive connector and the third conductive connector is greater than the bonding strength between the second conductive connector and the first conductive layer.

[0011] Optionally, the first conductive connector, the second conductive connector and the third conductive connector are an integrated structure.

[0012] Optionally, the first conductive connector, the second conductive connector and the third conductive connector satisfy at least one of the following: a side surface of the third conductive connector is discontinuous with a side surface of the first conductive connector; a side surface of the third conductive connector is discontinuous with a side surface of the second conductive connector.

[0013] Optionally, the first conductive connector, the second conductive connector and the third conductive connector satisfy at least one of the following: the area of ​​the end surface of the first conductive connector facing away from the third conductive connector is greater than the area of ​​the end surface of the first conductive connector facing the third conductive connector; the area of ​​the end surface of the second conductive connector facing away from the third conductive connector is greater than the area of ​​the end surface of the second conductive connector facing the third conductive connector; the area of ​​the end surface of the third conductive connector facing the first conductive connector is not greater than the area of ​​the end surface of the first conductive connector facing the third conductive connector; the area of ​​the end surface of the third conductive connector facing the second conductive connector is not greater than the area of ​​the end surface of the second conductive connector facing the third conductive connector.

[0014] Optionally, the first conductive connector, the second conductive connector and the third conductive connector satisfy at least one of the following: the edge of the end face of the first conductive connector facing the third conductive connector does not overlap with the edge of the end face of the third conductive connector facing the first conductive connector; the edge of the end face of the second conductive connector facing the third conductive connector does not overlap with the edge of the end face of the third conductive connector facing the second conductive connector.

[0015] Optionally, the first conductive connector, the second conductive connector and the third conductive connector satisfy at least one of the following: the lateral distance between the outer edge of the end surface of the first conductive connector facing the third conductive connector and the outer edge of the end surface of the third conductive connector facing the first conductive connector is less than 10 μm; the lateral distance between the outer edge of the end surface of the second conductive connector facing the third conductive connector and the outer edge of the end surface of the third conductive connector facing the second conductive connector is less than 10 μm.

[0016] Optionally, the third conductive connector includes one sub-conductive connector or a plurality of spaced sub-conductive connectors, and the sub-conductive connectors are connected to the first conductive connector and the second conductive connector respectively.

[0017] Optionally, the sub-conductive connector satisfies at least one of the following: the width of the end surface of the sub-conductive connector facing the first conductive connector is 20 μm to 50 μm; the width of the end surface of the sub-conductive connector facing the second conductive connector is 20 μm to 50 μm.

[0018] Optionally, the sub-conductive connector includes a first sub-connector, a second sub-connector and a third sub-connector connected in sequence in the thickness direction of the first conductive layer, the first sub-connector is connected to the first conductive connector, the third sub-connector is connected to the second conductive connector, and the first sub-connector, the second sub-connector and the third sub-connector satisfy at least one of the following: the area of ​​the end face of the first sub-connector facing away from the second sub-connector is greater than the area of ​​the end face of the first sub-connector facing the second sub-connector; the area of ​​the end face of the third sub-connector facing away from the second sub-connector is greater than the area of ​​the end face of the third sub-connector facing the second sub-connector.

[0019] Optionally, the first sub-connector, the second sub-connector and the third sub-connector satisfy at least one of the following: the end face of the first sub-connector facing the second sub-connector coincides with the end face of the second sub-connector facing the first sub-connector; the end face of the third sub-connector facing the second sub-connector coincides with the end face of the second sub-connector facing the third sub-connector.

[0020] Optionally, the first sub-connector, the second sub-connector and the third sub-connector satisfy at least one of the following: the angle between the side surface of the first sub-connector and the end surface of the first sub-connector facing the second sub-connector is an obtuse angle; the angle between the side surface of the third sub-connector and the end surface of the third sub-connector facing the second sub-connector is an obtuse angle.

[0021] Optionally, the first sub-connector, the second sub-connector and the third sub-connector satisfy at least one of the following: the angle between the side surface of the first sub-connector and the end surface of the first sub-connector facing the second sub-connector is greater than 90 degrees and less than or equal to 150 degrees; the angle between the side surface of the third sub-connector and the end surface of the third sub-connector facing the second sub-connector is greater than 90 degrees and less than or equal to 150 degrees.

[0022] Optionally, the first sub-connector, the second sub-connector and the third sub-connector are an integral structure.

[0023] Optionally, the angle between the side surface of the first conductive connector and the end surface of the first conductive connector facing the third conductive connector is an obtuse angle; the angle between the side surface of the second conductive connector and the end surface of the second conductive connector facing the third conductive connector is an obtuse angle.

[0024] Optionally, the angle between the side surface of the first conductive connector and the end surface of the first conductive connector facing the third conductive connector is greater than or equal to 90 degrees and less than or equal to 140 degrees; the angle between the side surface of the second conductive connector and the end surface of the second conductive connector facing the third conductive connector is greater than or equal to 90 degrees and less than or equal to 140 degrees.

[0025] Optionally, the first circuit board unit includes one first unit or multiple stacked first units, the first unit includes a stacked first insulating base layer and a second conductive layer; in any one of the first units, the second conductive layer is located on the side of the first insulating base layer away from the first conductive layer.

[0026] Optionally, the second circuit board unit includes one second unit or multiple stacked second units, and the second unit includes a stacked second insulating base layer and a third conductive layer; in any one of the second units, the third conductive layer is located on the side of the second insulating base layer away from the first conductive layer.

[0027] Optionally, the circuit board further includes:

[0028] a first soldering pad located on a side of the second circuit board unit facing away from the first circuit board unit, the first soldering pad being connected to the second conductive connector;

[0029] a soldering layer located on a side of the first soldering pad facing away from the second circuit board unit;

[0030] The electronic component is located on a side of the soldering layer away from the first soldering pad.

[0031] Optionally, the circuit board further includes: a second soldering pad located on a side of the first circuit board unit facing away from the second circuit board unit, and the second soldering pad is connected to the first conductive connector.

[0032] Optionally, the circuit board includes: a plurality of pads;

[0033] The plurality of pads are located on a side of the first circuit board unit facing away from the second circuit board unit and are connected to the first conductive connector; or,

[0034] The plurality of pads are located on a side of the second circuit board unit facing away from the first circuit board unit and are connected to the second conductive connector; or,

[0035] Some of the plurality of pads are located on a side of the first circuit board unit away from the second circuit board unit and connected to the first conductive connector, while other pads are located on a side of the second circuit board unit away from the first circuit board unit and connected to the second conductive connector.

[0036] Optionally, the circuit board is a flexible circuit board or a printed circuit board.

[0037] In a second aspect, a method for preparing a circuit board is provided, comprising:

[0038] forming a first circuit board unit, a first conductive layer, an adhesive layer, and a second circuit board unit stacked in sequence;

[0039] A first conductive connector is formed that passes through the first circuit board unit, a second conductive connector passes through the second circuit board unit and the adhesive layer, and a third conductive connector passes through the first conductive layer. The third conductive connector is connected to the first conductive connector and the second conductive connector, respectively. The bonding strength between the first conductive connector and the third conductive connector is greater than the bonding strength between the first conductive connector and the first conductive layer, and the bonding strength between the second conductive connector and the third conductive connector is greater than the bonding strength between the second conductive connector and the first conductive layer.

[0040] Optionally, forming a first conductive connector penetrating the first circuit board unit, a second conductive connector penetrating the second circuit board unit and the adhesive layer, and a third conductive connector penetrating the first conductive layer includes:

[0041] forming a first hole penetrating the first circuit board unit;

[0042] forming a second hole penetrating the second circuit board unit and the adhesive layer;

[0043] forming a third hole penetrating the first conductive layer, wherein the third hole is connected to the first hole and the second hole respectively;

[0044] The first conductive connection is formed in the first hole, the second conductive connection is formed in the second hole, and the third conductive connection is formed in the third hole.

[0045] Optionally, the first hole, the second hole, and the third hole satisfy at least one of the following: a side surface of the third hole is discontinuous with a side surface of the first hole; a side surface of the third hole is discontinuous with a side surface of the second hole; and correspondingly, the first conductive connector, the second conductive connector, and the third conductive connector satisfy at least one of the following: a side surface of the third conductive connector is discontinuous with a side surface of the first conductive connector; a side surface of the third conductive connector is discontinuous with a side surface of the second conductive connector. The side surface of a hole is also the surface of the side wall of the hole, and the side surface of a hole is also called a sidewall surface or sidewall.

[0046] Optionally, the first hole, the second hole and the third hole satisfy at least one of the following: the area of ​​the opening surface of the first hole facing away from the third hole is greater than the area of ​​the opening surface of the first hole facing the third hole; the area of ​​the opening surface of the second hole facing away from the third hole is greater than the area of ​​the opening surface of the second hole facing the third hole; the area of ​​the opening surface of the third hole facing the first hole is not greater than the area of ​​the opening surface of the first hole facing the third hole; the area of ​​the opening surface of the third hole facing the second hole is not greater than the area of ​​the opening surface of the second hole facing the third hole; correspondingly, the first conductive connector, the second conductive connector and the third conductive connector satisfy It is sufficient to have at least one of the following: the area of ​​the end face of the first conductive connector facing away from the third conductive connector is larger than the area of ​​the end face of the first conductive connector facing the third conductive connector; the area of ​​the end face of the second conductive connector facing away from the third conductive connector is larger than the area of ​​the end face of the second conductive connector facing the third conductive connector; the area of ​​the end face of the third conductive connector facing the first conductive connector is not larger than the area of ​​the end face of the first conductive connector facing the third conductive connector; the area of ​​the end face of the third conductive connector facing the second conductive connector is not larger than the area of ​​the end face of the second conductive connector facing the third conductive connector.

[0047] Optionally, the first hole, the second hole and the third hole satisfy at least one of the following: the edge of the opening surface of the first hole facing the third hole does not overlap with the edge of the opening surface of the third hole facing the first hole; the edge of the opening surface of the second hole facing the third hole does not overlap with the edge of the opening surface of the third hole facing the second hole; correspondingly, the first conductive connector, the second conductive connector and the third conductive connector satisfy at least one of the following: the edge of the end surface of the first conductive connector facing the third conductive connector does not overlap with the edge of the end surface of the third conductive connector facing the first conductive connector; the edge of the end surface of the second conductive connector facing the third conductive connector does not overlap with the edge of the end surface of the third conductive connector facing the second conductive connector.

[0048] Optionally, the first hole, the second hole and the third hole satisfy at least one of the following: the lateral distance between the outer edge of the opening surface of the first hole facing the third hole and the outer edge of the opening surface of the third hole facing the first hole is less than 10 μm; the lateral distance between the outer edge of the opening surface of the second hole facing the third hole and the outer edge of the opening surface of the third hole facing the second hole is less than 10 μm; correspondingly, the first conductive connector, the second conductive connector and the third conductive connector satisfy at least one of the following: the lateral distance between the outer edge of the end surface of the first conductive connector facing the third conductive connector and the outer edge of the end surface of the third conductive connector facing the first conductive connector is less than 10 μm; the lateral distance between the outer edge of the end surface of the second conductive connector facing the third conductive connector and the outer edge of the end surface of the third conductive connector facing the second conductive connector is less than 10 μm.

[0049] Optionally, the process of forming the first conductive connector in the first hole, the process of forming the second conductive connector in the second hole, and the process of forming the third conductive connector in the third hole include an electroplating process or a chemical plating process.

[0050] Optionally, a first conductive connector is formed in the first hole, a second conductive connector is formed in the second hole, and a third conductive connector is formed in the third hole through the same process. The first conductive connector, the second conductive connector, and the third conductive connector are an integrated structure.

[0051] Optionally, forming a third hole passing through the first conductive layer includes: forming a sub-hole passing through the first conductive layer or a plurality of sub-holes passing through the first conductive layer and spaced apart, each of the sub-holes being connected to the first hole and the second hole respectively; correspondingly, forming the third conductive connector in the third hole includes: forming a sub-conductive connector in each of the sub-holes.

[0052] Optionally, the sub-hole satisfies at least one of the following: the width of the opening surface of the sub-hole facing the first hole is 20μm to 50μm; the width of the opening surface of the sub-hole facing the second hole is 20μm to 50μm; correspondingly, the sub-conductive connector satisfies at least one of the following: the width of the end surface of the sub-conductive connector facing the first conductive connector is 20μm to 50μm; the width of the end surface of the sub-conductive connector facing the second conductive connector is 20μm to 50μm.

[0053] Optionally, forming any one of the sub-holes penetrating the first conductive layer includes:

[0054] forming a first groove on the first conductive layer at a portion exposed by the first hole, wherein an area of ​​an opening of the first groove is larger than an area of ​​a bottom surface of the first groove;

[0055] forming a third groove on the first conductive layer at a portion exposed by the second hole, wherein the area of ​​an opening of the third groove is larger than the area of ​​a bottom of the third groove, and a portion of the first conductive layer is located between the third groove and the first groove;

[0056] forming a second groove on the first conductive layer at a position between the third groove and the first groove, wherein the second groove is connected to the first groove and the third groove respectively to form the sub-hole;

[0057] Correspondingly, forming a sub-conductive connector in any one of the sub-holes includes: forming a first sub-connector in the first groove, forming a second sub-connector in the second groove, and forming a third sub-connector in the third groove.

[0058] Optionally, the first groove and the third groove satisfy at least one of the following: the angle between the side of the first groove and the bottom of the first groove is an obtuse angle; the angle between the side of the third groove and the bottom of the third groove is an obtuse angle; correspondingly, the first sub-connector and the third sub-connector satisfy at least one of the following: the angle between the side of the first sub-connector and the end face of the first sub-connector facing the second sub-connector is an obtuse angle; the angle between the side of the third sub-connector and the end face of the third sub-connector facing the second sub-connector is an obtuse angle.

[0059] Optionally, the first groove and the third groove satisfy at least one of the following: the angle between the side of the first groove and the bottom of the first groove is greater than 90 degrees and less than or equal to 150 degrees; the angle between the side of the third groove and the bottom of the third groove is greater than 90 degrees and less than or equal to 150 degrees; correspondingly, the first sub-connector and the third sub-connector satisfy at least one of the following: the angle between the side of the first sub-connector and the end face of the first sub-connector facing the second sub-connector is greater than 90 degrees and less than or equal to 150 degrees; the angle between the side of the third sub-connector and the end face of the third sub-connector facing the second sub-connector is greater than 90 degrees and less than or equal to 150 degrees.

[0060] Optionally, the first sub-connector is formed in the first groove, the second sub-connector is formed in the second groove, and the third sub-connector is formed in the third groove by the same process. The first sub-connector, the second sub-connector and the third sub-connector are an integrated structure.

[0061] Optionally, the angle between the side of the first hole and the opening surface of the first hole facing the third hole is an obtuse angle; the angle between the side of the second hole and the opening surface of the second hole facing the third hole is an obtuse angle; correspondingly, the angle between the side of the first conductive connector and the end surface of the first conductive connector facing the third conductive connector is an obtuse angle; the angle between the side of the second conductive connector and the end surface of the second conductive connector facing the third conductive connector is an obtuse angle.

[0062] Optionally, the angle between the side surface of the first hole and the opening surface of the first hole facing the third hole is greater than or equal to 90 degrees and less than or equal to 140 degrees; the angle between the side surface of the second hole and the opening surface of the second hole facing the third hole is greater than or equal to 90 degrees and less than or equal to 140 degrees. Correspondingly, the angle between the side surface of the first conductive connector and the end surface of the first conductive connector facing the third conductive connector is greater than or equal to 90 degrees and less than or equal to 140 degrees; the angle between the side surface of the second conductive connector and the end surface of the second conductive connector facing the third conductive connector is greater than or equal to 90 degrees and less than or equal to 140 degrees.

[0063] Optionally, the method further includes:

[0064] A first pad is formed on a side of the second circuit board unit facing away from the first circuit board unit, and the first pad is connected to the second conductive connector;

[0065] forming a soldering layer on a side of the first soldering pad facing away from the second circuit board unit;

[0066] An electronic component is formed on a side of the soldering layer facing away from the first soldering pad.

[0067] Optionally, the method further includes: forming a second pad on a side of the first circuit board unit facing away from the second circuit board unit, wherein the second pad is connected to the first conductive connector.

[0068] In a third aspect, a display module is provided, comprising: a display panel and a circuit board provided by the first aspect and its optional implementation, wherein the circuit board is electrically connected to the display panel.

[0069] In a fourth aspect, a display device is provided, comprising the display module provided in the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0071] FIG1 is a schematic diagram of a circuit board provided by the related art;

[0072] FIG2 is a schematic diagram of another circuit board provided by the related art;

[0073] FIG3 is a schematic diagram of removing residual material debris provided by the related art;

[0074] FIG4 is a schematic diagram of a circuit board provided in an embodiment of the present application;

[0075] FIG5 is a schematic diagram of another circuit board provided in an embodiment of the present application;

[0076] FIG6 is a flow chart of a method for preparing a circuit board provided in an embodiment of the present application;

[0077] 7 to 10 and 13 are schematic diagrams of a process for preparing a circuit board according to an embodiment of the present application;

[0078] Figures 7 to 9 and Figures 14 to 17 are schematic diagrams of another process for preparing a circuit board provided in an embodiment of the present application;

[0079] FIG11 is a top view of the second hole G2 in FIG10;

[0080] FIG12 is a schematic diagram of removing residual material debris provided in an embodiment of the present application. DETAILED DESCRIPTION

[0081] Figure 1 is a schematic diagram of a circuit board provided by the related art. The circuit board includes a first circuit board A, a second circuit board B, and an adhesive layer C located between the first circuit board A and the second circuit board B. The first circuit board A includes a first conductive layer 11, a second conductive layer 12, and a first insulating base layer 10 located between the first conductive layer 11 and the second conductive layer 12. The second circuit board B includes a second insulating base layer 13 and a third conductive layer 14 located on the side of the second insulating base layer 13 facing away from the adhesive layer C. The circuit board also includes: a through hole K extending through the first circuit board A, the second circuit board B, and the adhesive layer C; a conductive connecting film 17 located on the side of the through hole K; a first soldering pad 15 located on the side of the second circuit board B facing away from the adhesive layer C and connected to the conductive connecting film 17; a second soldering pad 16 located on the side of the first circuit board A facing away from the adhesive layer C and connected to the conductive connecting film 17; a soldering layer 18 located on the side of the first soldering pad 15 facing away from the second circuit board B, the soldering layer 18 covering the through hole K; and an electronic component 19 located on the side of the soldering layer 18 facing away from the first soldering pad 15. The side surface of the through hole K is also the surface of the side wall of the through hole K, and is also called the side wall surface or side wall of the through hole K.

[0082] In the circuit board shown in Figure 1, a conductive connection film 17 is used to connect the conductive layer of the first circuit board A to the conductive layer of the second circuit board B. However, because through-hole K is located below solder layer 18, and solder layer 18 covers through-hole K, the gas within through-hole K expands due to heat during the soldering process of electronic component 19 to solder layer 18, causing solder layer 18 to deform. The gas within through-hole K passes through the deformed solder layer 18 to the outside of through-hole K. As the gas passes through solder layer 18, cracks are formed in solder layer 18, resulting in a poor connection between electronic component 19 and solder layer 18.

[0083] Figure 2 is a schematic diagram of another circuit board provided by the related art. The circuit board includes: a first circuit board A, a second circuit board B, and an adhesive layer C located between the first circuit board A and the second circuit board B. The first circuit board A includes a first conductive layer 11, a second conductive layer 12, and a first insulating base layer 10 located between the first conductive layer 11 and the second conductive layer 12. The second circuit board B includes a second insulating base layer 13 and a third conductive layer 14 located on the side of the second insulating base layer 13 facing away from the adhesive layer C. The circuit board also includes: a first conductive connector 17a that passes through the second conductive layer 12 and the first insulating base layer 10; and a second conductive connector 17b that passes through the second circuit board B and the adhesive layer C. The first conductive connector 17a and the second conductive connector 17b have a first conductive layer 11 between them, and the first conductive connector 17a and the second conductive connector 17b are both connected to the first conductive layer 11. The first conductive connector 17a and the second conductive connector 17b are used to connect the conductive layers in the first circuit board A and the conductive layers in the second circuit board B.

[0084] The process of forming the first conductive connector 17a and the second conductive connector 17b includes: forming a first hole through the second conductive layer 12 and the first insulating base layer 10, with the bottom of the first hole exposing the first conductive layer 11; forming a second hole through the second circuit board B and the adhesive layer C, with the bottom of the second hole exposing the first conductive layer 11; forming the first conductive connector 17a in the first hole; and forming the second conductive connector 17b in the second hole. Because the first hole has a small aspect ratio, the first conductive connector 17a can completely fill the first hole. Because the second hole has a small aspect ratio, the second conductive connector 17b can completely fill the second hole. This prevents the gas in the first and second holes from being heated and passing through the soldering layer 18 during soldering of the electronic component 19 to the soldering layer 18. Cracks in the soldering layer 18 are prevented, and the connection between the electronic component 19 and the soldering layer 18 is highly secure. The aspect ratio of the first hole is the ratio of the height of the first hole to its width. The height of the first hole is the dimension of the first hole in a direction perpendicular to the surface of the first circuit board A. The width of the first hole is the dimension of the first hole in a direction parallel to the surface of the first circuit board A. The height of the first hole is also called the depth of the first hole, and the width of the first hole is also called the aperture of the first hole. The meaning of the aspect ratio of the second hole is similar.

[0085] However, for the circuit board shown in FIG2 , when soldering the electronic component 19 to the soldering layer 18 using a soldering process, heat is conducted along the first and second conductive connectors 17a, 17b to the adhesive layer C, causing thermal expansion of the adhesive layer C. As the adhesive layer C cools and contracts after being heated, it is prone to significant deformation, stretching the first conductive layer 11. This can cause cracks in the portion of the first conductive layer 11 between the first and second conductive connectors 17a, 17b (the portion within the dashed box in FIG2 ). These cracks can easily affect the reliability of the connection between the first and second conductive connectors 17a, 17b.

[0086] In addition, in the process of forming the first hole and the second hole, material fragments of other layers will inevitably remain in the first hole and the second hole. For example, material fragments of the second conductive layer 12 and material fragments of the first insulating base layer 10 will remain in the first hole, and material fragments of the second insulating base layer 13, material fragments of the third conductive layer 14 and material fragments of the adhesive layer C will remain in the second hole (the material fragments of the adhesive layer C are also called residual glue). Therefore, it is necessary to remove the material fragments remaining in the first hole and the second hole. Generally, the first hole and the second hole can be flushed by spraying a liquid medicine into the first hole and the second hole to remove the material fragments remaining in the first hole and the second hole. For example, Figure 3 is a schematic diagram of removing the material fragments remaining in the second hole provided by the related art. The liquid medicine is sprayed into the second hole so that the residual glue in the second hole is dissolved in the liquid medicine, thereby achieving the effect of removing the residual glue in the second hole. However, the first hole and the second hole are both blind holes. In the process of removing the residual material debris in the first hole and the second hole by spraying the liquid medicine, a "pool effect" is easily generated in the first hole and the second hole (Figure 3 shows the situation where the "pool effect" occurs in the second hole), that is, the liquid medicine will accumulate in the first hole and the second hole, the fluidity of the liquid medicine in the first hole and the second hole is poor, and the liquid medicine has a poor flushing effect on the bottom of the first hole and the bottom of the second hole. If the time of spraying the liquid medicine into the first hole and the second hole is short, it will not be possible to completely remove the residual material debris in the first hole and the second hole, resulting in poor results in the coating process of forming the first conductive connector 17a in the first hole and the coating process of forming the second conductive connector 17b in the second hole, affecting the conductive effect between the first conductive connector 17a and the first conductive layer 11 and the conductive effect between the second conductive connector 17b and the first conductive layer 11. If the chemical solution is sprayed into the first and second holes for a long time, the chemical solution may easily damage the portion of the first conductive layer 11 exposed in the first and second holes, resulting in a reduction in the thickness of the portion of the first conductive layer 11 located between the first and second conductive connectors 17a, 17b. This, in turn, may make the portion of the first conductive layer 11 located between the first and second conductive connectors 17a, 17b more susceptible to cracking due to the stretching of the adhesive layer C. During the soldering process of the electronic component 19 on the soldering layer 18, the cracks in the first conductive layer 11 may further expand under the influence of the high temperature environment, potentially causing a short circuit between the first and second conductive connectors 17a, 17b.

[0087] It can be seen that the circuit board shown in FIG. 2 still has the problem of poor reliability.

[0088] The present invention provides a circuit board and a method for manufacturing the same, a display module, and a display device. The circuit board has high reliability, and thus the display module and display device including the circuit board have high reliability.

[0089] The technical solutions of the embodiments of the present application will be described below in conjunction with the accompanying drawings. Obviously, the embodiments described below are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments described below, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0090] In the description of the embodiments of the present application, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" and similar expressions are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal communication of two elements, or a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0091] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0092] FIG4 is a schematic diagram of a circuit board 400 provided in an embodiment of the present application. Referring to FIG4 , the circuit board 400 includes: a first circuit board unit A1, a first conductive layer 110, an adhesive layer C1, and a second circuit board unit B1 stacked in sequence; a first conductive connector 170a extending through the first circuit board unit A1; a second conductive connector 170b extending through the second circuit board unit B1 and the adhesive layer C1; and a third conductive connector 170c extending through the first conductive layer 110. The third conductive connector 170c is connected to the first conductive connector 170a and the second conductive connector 170b, respectively. The bonding strength between the first conductive connector 170a and the third conductive connector 170c is greater than the bonding strength between the first conductive connector 170a and the first conductive layer 110, and the bonding strength between the second conductive connector 170b and the third conductive connector 170c is greater than the bonding strength between the second conductive connector 170b and the first conductive layer 110. In this way, even in a high-temperature process environment, heat is conducted along the first and second conductive connectors 170a and 170b to the adhesive layer C1, causing the adhesive layer C1 to expand due to the heat. Even if the adhesive layer C1 deforms during the process of cooling and shrinking after being heated, thereby stretching the first conductive layer 110, the third conductive connector 170c is connected to the first and second conductive connectors 170a and 170b, respectively. The bonding strength between the first and third conductive connectors 170a and 170c is greater than the bonding strength between the first and first conductive layers 110, and the bonding strength between the second and third conductive connectors 170b and 170c is greater than the bonding strength between the second and first conductive layers 110. In other words, the first and second conductive connectors 170a and 170b are connected via the third conductive connector 170c, which has a greater bonding strength to each of them. Therefore, the adhesive layer C1 stretching the first conductive layer 110 does not affect the reliability of the connection between the first conductive connector 170a and the second conductive connector 170b, thereby not affecting the conduction effect of the first conductive connector 170a and the second conductive connector 170b, and will not cause a circuit break between the first conductive connector 170a and the second conductive connector 170b, so the reliability is higher.

[0093] Furthermore, the bonding strength between the third conductive connector 170c and the first conductive connector 170a is greater than the bonding strength between the third conductive connector 170c and the first conductive layer 110, and the bonding strength between the third conductive connector 170c and the second conductive connector 170b is greater than the bonding strength between the third conductive connector 170c and the first conductive layer 110. In an alternative embodiment, the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c are integrally formed. In this manner, the first conductive connector 170a and the third conductive connector 170c are bonded to each other through atomic bonding, and the second conductive connector 170b and the third conductive connector 170c are bonded to each other through atomic bonding. The bonding strength between the first conductive connector 170a and the third conductive connector 170c is greater, and the bonding strength between the second conductive connector 170b and the third conductive connector 170c is greater. Since the first conductive connector 170a and the first conductive layer 110 are independent structures, the second conductive connector 170b and the first conductive layer 110 are independent structures, and the third conductive connector 170c and the first conductive layer 110 are independent structures; therefore, the bonding strength between the first conductive connector 170a and the third conductive connector 170c is greater than the bonding strength between the first conductive connector 170a and the first conductive layer 110; the bonding strength between the second conductive connector 170b and the third conductive connector 170c is greater than the bonding strength between the second conductive connector 170b and the first conductive layer 110; the bonding strength between the third conductive connector 170c and the first conductive connector 170a and the bonding strength between the third conductive connector 170c and the second conductive connector 170b are both greater than the bonding strength between the third conductive connector 170c and the first conductive layer 110. In the embodiment of the present application, the first conductive connector 170a, the second conductive connector 170b and the third conductive connector 170c are arranged as an integrated structure, which can improve the bonding strength between the first conductive connector 170a and the third conductive connector 170c and improve the bonding strength between the second conductive connector 170b and the third conductive connector 170c, so that the first conductive connector 170a and the third conductive connector 170c are not easily pulled apart, and the second conductive connector 170b and the third conductive connector 170c are not easily pulled apart.

[0094] In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c meet at least one of the following conditions: the side surface of the third conductive connector 170c is discontinuous with the side surface of the first conductive connector 170a. Because the side surface of the third conductive connector 170c is discontinuous with the side surface of the first conductive connector 170a, the connecting surface of the first conductive connector 170a and the third conductive connector 170c forms a certain angle with the side surface of the first conductive connector 170a. Compared with the related art of FIG. 1, the height-to-width ratio of the first conductive connector 170a is smaller, and cracks are less likely to form inside the first conductive connector 170a during the manufacturing process. Because the side surfaces of the third conductive connector 170c are discontinuous with the side surfaces of the second conductive connector 170b, a certain angle exists between the connecting surface of the second conductive connector 170b and the third conductive connector 170c and the side surfaces of the second conductive connector 170b. Compared to the related art shown in FIG1 , the height-to-width ratio of the second conductive connector 170b is smaller, and cracks are less likely to form within the second conductive connector 170b during the manufacturing process. This can improve the soldering strength between the first conductive connector 170a and subsequent electronic components, and / or improve the soldering strength between the second conductive connector 170b and subsequent electronic components.

[0095] In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b and the third conductive connector 170c satisfy at least one of the following: the area of ​​the end surface of the first conductive connector 170a facing away from the third conductive connector 170c is greater than the area of ​​the end surface of the first conductive connector 170a facing the third conductive connector 170c; the area of ​​the end surface of the second conductive connector 170b facing away from the third conductive connector 170c is greater than the area of ​​the end surface of the second conductive connector 170b facing the third conductive connector 170c; the area of ​​the end surface of the third conductive connector 170c facing the first conductive connector 170a is not greater than the area of ​​the end surface of the first conductive connector 170a facing the third conductive connector 170c; the area of ​​the end surface of the third conductive connector 170c facing the second conductive connector 170b is not greater than the area of ​​the end surface of the second conductive connector 170b facing the third conductive connector 170c. In this way, it can be achieved that the side surface of the third conductive connector 170 c is discontinuous with the side surface of the first conductive connector 170 a ; and / or the side surface of the third conductive connector 170 c is discontinuous with the side surface of the second conductive connector 170 b .

[0096] In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c meet at least one of the following conditions: the edge of the end surface of the first conductive connector 170a facing the third conductive connector 170c does not overlap with the edge of the end surface of the third conductive connector 170c facing the first conductive connector 170a; the edge of the end surface of the second conductive connector 170b facing the third conductive connector 170c does not overlap with the edge of the end surface of the third conductive connector 170c facing the second conductive connector 170b. In this way, the side surface of the third conductive connector 170c can be discontinuous with the side surface of the first conductive connector 170a; and / or the side surface of the third conductive connector 170c can be discontinuous with the side surface of the second conductive connector 170b. For example, as shown in Figure 4, the edge of the end face of the first conductive connector 170a facing the third conductive connector 170c does not overlap with the edge of the end face of the third conductive connector 170c facing the first conductive connector 170a, and the edge of the end face of the second conductive connector 170b facing the third conductive connector 170c does not overlap with the edge of the end face of the third conductive connector 170c facing the second conductive connector 170b.

[0097] Circuit board 400 is a flexible circuit board or printed circuit board. A printed circuit board enables the electrical connection of electronic components along predetermined circuits. A flexible circuit board, also known as a flexible printed circuit board (FPC), is a highly reliable and flexible circuit board made from a flexible material such as polyimide or polyester film.

[0098] In an optional embodiment, the first circuit board unit A1 includes a single first unit or multiple stacked first units, each of which includes a first insulating base layer 100 and a second conductive layer 120. In any first unit, the second conductive layer 120 is located on the side of the first insulating base layer 100 facing away from the first conductive layer 110. In any first unit, the second conductive layer 120 contacts the first insulating base layer 100; for example, the second conductive layer 120 is located on the surface of the first insulating base layer 100 facing away from the first conductive layer 110. Figure 4 illustrates a case where the first circuit board unit A1 includes a single first unit. In other embodiments, the first circuit board unit A1 includes multiple stacked first units. If the circuit board 400 is a flexible circuit board, the first insulating base layer 100 is a flexible insulating base layer, such as one made of polyimide. If the circuit board 400 is a printed circuit board, the first insulating base layer 100 is a rigid insulating base layer.

[0099] In an optional embodiment, the second circuit board unit B1 includes a single second unit or multiple stacked second units, each of which includes a second insulating base layer 130 and a third conductive layer 140. In any second unit, the third conductive layer 140 is located on the side of the second insulating base layer 130 facing away from the first conductive layer 110. In any second unit, the third conductive layer 140 contacts the second insulating base layer 130; for example, the third conductive layer 140 is located on the surface of the second insulating base layer 130 facing away from the first conductive layer 110. Figure 4 illustrates a case where the second circuit board unit B1 includes a single second unit. In other embodiments, the second circuit board unit B1 includes multiple stacked second units. If the circuit board 400 is a flexible circuit board, the second insulating base layer 130 is a flexible insulating base layer, such as one made of polyimide. If the circuit board 400 is a printed circuit board, the second insulating base layer 130 is a rigid insulating base layer.

[0100] The first conductive connector 170a is made of a metal, including but not limited to copper, or other conductive metal materials. The second conductive connector 170b is made of a metal, including but not limited to copper, or other conductive metal materials. The third conductive connector 170c is made of a metal, including but not limited to copper, or other conductive metal materials.

[0101] The thermal expansion coefficient of the adhesive layer C1 is higher than the thermal expansion coefficient of the first conductive connector 170a, the thermal expansion coefficient of the adhesive layer C1 is higher than the thermal expansion coefficient of the second conductive connector 170b, and the thermal expansion coefficient of the adhesive layer C1 is higher than the thermal expansion coefficient of the third conductive connector 170c. Furthermore, the thermal expansion coefficient of the adhesive layer C1 is much higher than the thermal expansion coefficient of the first conductive connector 170a, the thermal expansion coefficient of the adhesive layer C1 is much higher than the thermal expansion coefficient of the second conductive connector 170b, and the thermal expansion coefficient of the adhesive layer C1 is much higher than the thermal expansion coefficient of the third conductive connector 170c. For example, the difference between the thermal expansion coefficient of the adhesive layer C1 and the thermal expansion coefficient of the first conductive connector 170a is greater than a preset difference, the difference between the thermal expansion coefficient of the adhesive layer C1 and the thermal expansion coefficient of the second conductive connector 170b is greater than a preset difference, and the difference between the thermal expansion coefficient of the adhesive layer C1 and the thermal expansion coefficient of the third conductive connector 170c is greater than a preset difference. In one embodiment, the thermal expansion coefficient of the adhesive layer C1 is 275 ppm / °C, the thermal expansion coefficient of the first conductive connector 170a is 16 ppm / °C to 18 ppm / °C, the thermal expansion coefficient of the second conductive connector 170b is 16 ppm / °C to 18 ppm / °C, and the thermal expansion coefficient of the third conductive connector 170c is 16 ppm / °C to 18 ppm / °C. "ppm" stands for parts per million in English and one part per million in Chinese, and "°C" represents degrees Celsius.

[0102] In an embodiment of the present application, the third conductive connector 170c includes one sub-conductive connector 170d or a plurality of sub-conductive connectors 170d spaced apart, and the sub-conductive connector 170d is connected to the first conductive connector 170a and the second conductive connector 170b, respectively. In the case where the third conductive connector 170c includes one sub-conductive connector 170d, the one sub-conductive connector 170d is the third conductive connector 170c. For example, FIG4 illustrates an example in which the third conductive connector 170c includes one sub-conductive connector 170d. In other embodiments, one third conductive connector 170c includes a plurality of sub-conductive connectors 170d spaced apart, the plurality of sub-conductive connectors 170d are independent of each other, and each sub-conductive connector 170d of the plurality of sub-conductive connectors 170d is connected to the first conductive connector 170a and the second conductive connector 170b, respectively. It should be noted that the circuit board 400 may include at least one first conductive connector 170a and at least one second conductive connector 170b. The at least one first conductive connector 170a corresponds to the at least one second conductive connector 170b on a one-to-one basis. A third conductive connector 170c may be provided between each first conductive connector 170a and its corresponding second conductive connector 170b. If there are multiple first conductive connectors 170a and multiple second conductive connectors 170b, there may also be multiple third conductive connectors 170c. If there are only one first conductive connector 170a and one second conductive connector 170b, there may also be only one third conductive connector 170c.

[0103] In an optional embodiment, the side surface of the third conductive connector 170c is discontinuous with the side surface of the first conductive connector 170a, and the side surface of the third conductive connector 170c is discontinuous with the side surface of the second conductive connector 170b. When a third conductive connector 170c includes a sub-conductive connector 170d, the side surface of the third conductive connector 170c is the side surface of the sub-conductive connector 170d. When a third conductive connector 170c includes a plurality of spaced sub-conductive connectors 170d, the side surface of the third conductive connector 170c includes the side surface of each of the plurality of sub-conductive connectors 170d, the side surface of each sub-conductive connector 170d is discontinuous with the side surface of the first conductive connector 170a, and the side surface of each sub-conductive connector 170d is discontinuous with the side surface of the second conductive connector 170b. In the embodiment of the present application, the side surfaces of the third conductive connector 170c are discontinuous with the side surfaces of the first conductive connector 170a, and the side surfaces of the third conductive connector 170c are discontinuous with the side surfaces of the second conductive connector 170b. This can, on the one hand, reduce the difficulty of manufacturing the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c; on the other hand, it can improve the reliability of the connection between the third conductive connector 170c and the first conductive connector 170a, and on the other hand, improve the reliability of the connection between the third conductive connector 170c and the second conductive connector 170b. It should be noted that, in some embodiments, the side surfaces of the third conductive connector 170c being discontinuous with the side surfaces of the first conductive connector 170a can also be described as: there is a gap between the side surfaces of the third conductive connector 170c and the side surfaces of the first conductive connector 170a, or the side surfaces of the third conductive connector 170c are spaced apart from the side surfaces of the first conductive connector 170a. The fact that the side surface of the third conductive connector 170c is discontinuous with the side surface of the second conductive connector 170b can also be described as: there is a gap between the side surface of the third conductive connector 170c and the side surface of the second conductive connector 170b, or the side surface of the third conductive connector 170c is spaced apart from the side surface of the second conductive connector 170b. This embodiment of the present application is not limited to this.

[0104] In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c meet at least one of the following requirements: a lateral distance x1 between an outer edge of the end surface of the first conductive connector 170a facing the third conductive connector 170c and an outer edge of the end surface of the third conductive connector 170c facing the first conductive connector 170a is less than 10 μm (micrometers); and a lateral distance x2 between an outer edge of the end surface of the second conductive connector 170b facing the third conductive connector 170c and an outer edge of the end surface of the third conductive connector 170c facing the second conductive connector 170b is less than 10 μm. For example, x1 is 9.5 μm, 9 μm, or 8 μm, and / or x2 is 9.5 μm, 9 μm, or 8 μm. This provides a larger design space for the third conductive connector 170c. In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c further satisfy at least one of the following conditions: a lateral distance x1 between an outer edge of an end surface of the first conductive connector 170a facing the third conductive connector 170c and an outer edge of an end surface of the third conductive connector 170c facing the first conductive connector 170a is greater than or equal to 8 μm; and a lateral distance x2 between an outer edge of an end surface of the second conductive connector 170b facing the third conductive connector 170c and an outer edge of an end surface of the third conductive connector 170c facing the second conductive connector 170b is greater than or equal to 8 μm. In this manner, during the formation of the first conductive connector 170a, cracks are less likely to form in the first conductive connector 170a, thereby improving the reliability of the first conductive connector 170a. During the formation of the second conductive connector 170b, cracks are less likely to form in the second conductive connector 170b, thereby improving the reliability of the second conductive connector 170b.

[0105] As previously described, the third conductive connector 170c includes one sub-conductive connector 170d, or includes multiple sub-conductive connectors 170d spaced apart. When the third conductive connector 170c includes multiple sub-conductive connectors 170d, the outer edge of the end surface of the third conductive connector 170c facing the first conductive connector 170a refers to the outer edge of the end surface of the third conductive connector 170c facing the first conductive connector 170a as a whole; the outer edge of the end surface of the third conductive connector 170c facing the second conductive connector 170b refers to the outer edge of the end surface of the third conductive connector 170c facing the second conductive connector 170b as a whole. The lateral distance refers to the distance in a direction parallel to the first conductive layer 110.

[0106] It should be noted that, in other embodiments, there is no restriction on the lateral distance x1 between the outer edge of the end face of the first conductive connector 170a facing the third conductive connector 170c and the outer edge of the end face of the third conductive connector 170c facing the first conductive connector 170a, and there is no restriction on the lateral distance x2 between the outer edge of the end face of the second conductive connector 170b facing the third conductive connector 170c and the outer edge of the end face of the third conductive connector 170c facing the second conductive connector 170b.

[0107] In other embodiments, a portion of the side surface of the third conductive connector 170c is continuous with the side surface of the first conductive connector 170a, while another portion of the side surface of the third conductive connector 170c is discontinuous with the side surface of the first conductive connector 170a. In other embodiments, a portion of the side surface of the third conductive connector 170c is continuous with the side surface of the second conductive connector 170b, while another portion of the side surface of the third conductive connector 170c is continuous with the side surface of the second conductive connector 170b. For example, the third conductive connector 170c includes a plurality of spaced-apart sub-conductive connectors 170d, some of which have side surfaces that are continuous with the side surface of the first conductive connector 170a, while others have side surfaces that are discontinuous with the side surface of the first conductive connector 170a; some of which have side surfaces that are continuous with the side surface of the second conductive connector 170b, while others have side surfaces that are discontinuous with the side surface of the second conductive connector 170b.

[0108] In an optional embodiment, the sub-conductive connector 170d satisfies at least one of the following conditions: a width w1 of the end surface of the sub-conductive connector 170d facing the first conductive connector 170a is smaller than a width w2 of the end surface of the first conductive connector 170a facing the sub-conductive connector 170d; and a width w3 of the end surface of the sub-conductive connector 170d facing the second conductive connector 170b is smaller than a width w4 of the end surface of the second conductive connector 170b facing the sub-conductive connector 170d. For example, as shown in FIG. 4 , w1 is smaller than w2, and w3 is smaller than w4.

[0109] In an optional embodiment, the width w1 of the end surface of the sub-conductive connector 170d facing the first conductive connector 170a is 20 μm to 50 μm; and / or the width w3 of the end surface of the sub-conductive connector 170d facing the second conductive connector 170b is 20 μm to 50 μm. For example, w1 is 20 μm, 35 μm, 40 μm, 45 μm, or 50 μm, and w3 is 20 μm, 35 μm, 40 μm, 45 μm, or 50 μm.

[0110] For ease of description, the end surface of the sub-conductive connector 170d facing the first conductive connector 170a is referred to as the first end surface, and the end surface of the sub-conductive connector 170d facing the second conductive connector 170b is referred to as the second end surface. The shape of the first end surface and the shape of the second end surface can both be circular, elliptical, elongated, or irregular. The embodiments of the present application do not limit the shapes of the first end surface and the second end surface.

[0111] If the first and second end surfaces are both circular, the width of the first end surface is the diameter of the first end surface, and the width of the second end surface is the diameter of the second end surface. If the first and second end surfaces are both elliptical, the width of the first end surface is the length of the minor axis of the first end surface, and the width of the second end surface is the length of the minor axis of the second end surface. If the first and second end surfaces are both elongated, the width of the first end surface is perpendicular to the length of the first end surface, and the width of the second end surface is perpendicular to the length of the second end surface. The width of the first end surface is the dimension perpendicular to the length of the first end surface, and the width of the second end surface is the dimension perpendicular to the length of the second end surface. If the first and second end surfaces are both irregular, the width of the first end surface is the length of the shortest straight line segment passing through the geometric center of the first end surface and with its two endpoints located on the edges of the first end surface, and the width of the second end surface is the length of the shortest straight line segment passing through the geometric center of the second end surface and with its two endpoints located on the edges of the second end surface.

[0112] In an optional embodiment, the sub-conductive connector 170d has a uniform shape in each cross-section in a direction perpendicular to the thickness of the first conductive layer 110, and has a uniform area in each cross-section in the direction perpendicular to the thickness of the first conductive layer 110. For example, the sub-conductive connector 170d has a circular shape in each cross-section in a direction perpendicular to the thickness of the first conductive layer 110, and the sub-conductive connector 170d has a cylindrical structure. In other embodiments, the sub-conductive connector 170d has different shapes and / or areas in different cross-sections in the direction perpendicular to the thickness of the first conductive layer 110.

[0113] In an optional embodiment, the angle between the side surface of the first conductive connector 170a and the end surface of the first conductive connector 170a facing the third conductive connector 170c is an obtuse angle; the angle between the side surface of the second conductive connector 170b and the end surface of the second conductive connector 170b facing the third conductive connector 170c is an obtuse angle. In one embodiment, the angle between the side surface of the first conductive connector 170a and the end surface of the first conductive connector 170a facing the third conductive connector 170c is greater than or equal to 90 degrees and less than or equal to 140 degrees; the angle between the side surface of the second conductive connector 170b and the end surface of the second conductive connector 170b facing the third conductive connector 170c is greater than or equal to 90 degrees and less than or equal to 140 degrees. For example, the angle between the side surface of the first conductive connector 170a and the end surface of the first conductive connector 170a facing the third conductive connector 170c is 90°, 100°, 110°, 120°, 130° or 140°; and / or, the angle between the side surface of the second conductive connector 170b and the end surface of the second conductive connector 170b facing the third conductive connector 170c is 90°, 100°, 110°, 120°, 130° or 140°.

[0114] The angle between the side surface of the first conductive connector 170a and the end surface of the first conductive connector 170a facing the third conductive connector 170c cannot be too large or too small (for example, less than 90 degrees), otherwise it will be difficult to prepare the first conductive connector 170a. The angle between the side surface of the second conductive connector 170b and the end surface of the second conductive connector 170b facing the third conductive connector 170c cannot be too large or too small (for example, less than 90 degrees), otherwise it will be difficult to prepare the second conductive connector 170b. In the embodiment of the present application, the angle between the side surface of the first conductive connector 170a and the end surface of the first conductive connector 170a facing the third conductive connector 170c is greater than or equal to 90 degrees and less than or equal to 140 degrees, which can facilitate the preparation of the first conductive connector 170a. In the embodiment of the present application, the angle between the side surface of the second conductive connector 170b and the end surface of the second conductive connector 170b facing the third conductive connector 170c is greater than or equal to 90 degrees and less than or equal to 140 degrees, which can facilitate the preparation of the first conductive connector 170a.

[0115] It should be noted that, in other embodiments, there is no restriction on the angle between the side surface of the first conductive connector 170a and the end surface of the first conductive connector 170a facing the third conductive connector 170c, and there is no restriction on the angle between the side surface of the second conductive connector 170b and the end surface of the second conductive connector 170b facing the third conductive connector 170c.

[0116] In the embodiment of the present application, the arrangement of the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c results in lower loss in the first conductive layer 110 located between the first conductive connector 170a and the second conductive connector 170b. Therefore, the thickness of the first conductive layer 110 located between the first conductive connector 170a and the second conductive connector 170b is greater than the thickness of the first conductive layer 11 located between the first conductive connector 17a and the second conductive connector 17b in FIG2 . In one embodiment, the thickness of the first conductive layer 110 located between the first conductive connector 170a and the second conductive connector 170b is 6 μm to 10 μm, for example, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. This makes the first conductive layer 110 less susceptible to stretching by the adhesive layer C1, reducing the probability of cracks in the first conductive layer 110. It should be noted that in other embodiments, the thickness of the first conductive layer 110 is not limited.

[0117] In an optional embodiment, as shown in FIG4 , the circuit board 400 further includes a first solder pad 150a, a soldering layer 180, and an electronic component 190. The first solder pad 150a is located on a side of the second circuit board unit B1 facing away from the first circuit board unit A1, and the first solder pad 150a is connected to the second conductive connector 170b. For example, the first solder pad 150a and the second conductive connector 170b are integrally formed. The soldering layer 180 is located on a side of the first solder pad 150a facing away from the second circuit board unit B1, and the soldering layer 180 is connected to the first solder pad 150a. The electronic component 190 is located on a side of the soldering layer 180 facing away from the first solder pad 150a, and the electronic component 190 is soldered to the soldering layer 180.

[0118] As shown in Figure 4, the circuit board 400 further includes a second pad 150b located on a side of the first circuit board unit A1 away from the second circuit board unit B1, the second pad 150b being connected to the first conductive connector 170a. For example, the second pad 150b and the first conductive connector 170a are integrally formed.

[0119] In an optional embodiment, the circuit board 400 includes a plurality of solder pads. The plurality of solder pads are located on a side of the first circuit board unit A1 facing away from the second circuit board unit B1 and are connected to the first conductive connector 170a. Alternatively, the plurality of solder pads are located on a side of the second circuit board unit B1 facing away from the first circuit board unit A1 and are connected to the second conductive connector 170b. Alternatively, some of the plurality of solder pads are located on a side of the first circuit board unit A1 facing away from the second circuit board unit B1 and are connected to the first conductive connector 170a, while other solder pads are located on a side of the second circuit board unit B1 facing away from the first circuit board unit A1 and are connected to the second conductive connector 170b.

[0120] The material of the welding layer 180 includes solder paste. The electronic component 190 includes a resistor or a capacitor, and may also include other passive components, which is not limited in the embodiment of the present application.

[0121] In an optional embodiment, as shown in FIG4 , the circuit board 400 further includes a first insulating protective film 160, a first electromagnetic shielding layer 161, a second insulating protective film 162, and a second electromagnetic shielding layer 163. The first insulating protective film 160 is located on the side of the first circuit board unit A1 facing away from the second circuit board unit B1 and covers the first conductive connector 170a and the second solder pad 150b. The first electromagnetic shielding layer 161 is located on the side of the first insulating protective film 160 facing away from the first circuit board unit A1. The second insulating protective film 162 is located on the side of the second circuit board unit B1 facing away from the first circuit board unit A1. The second electromagnetic shielding layer 163 is located on the side of the second insulating protective film 162 facing away from the second circuit board unit B1. The circuit board 400 further includes a solder pad hole extending through the second insulating protective film 162 and the second electromagnetic shielding layer 163, with the solder layer 180 located in the solder pad hole. The solder pad hole can be circular, rectangular, or irregularly shaped. The diameter of the solder pad hole should not be too large and should match the position range of the electronic component 190. When the aperture of the pad hole is determined, the angle between the side surface of the first conductive connector 170a and the end surface of the first conductive connector 170a facing the third conductive connector 170c cannot be too large or too small; the angle between the side surface of the second conductive connector 170b and the end surface of the second conductive connector 170b facing the third conductive connector 170c cannot be too large or too small.

[0122] In an alternative embodiment, please refer to FIG5 , which shows a schematic diagram of another circuit board 500 provided in an embodiment of the present application. Unlike the circuit board 400 shown in FIG4 , in the circuit board 500 shown in FIG5 , the sub-conductive connector 170d includes a first sub-connector 171d, a second sub-connector 172d, and a third sub-connector 173d connected sequentially in the thickness direction of the first conductive layer 110, the second sub-connector 172d is located between the first sub-connector 171d and the third sub-connector 173d, the first sub-connector 171d is connected to the first conductive connector 170a, and the third sub-connector 173d is connected to the second conductive connector 170b. Among them, the first sub-connector 171d and the third sub-connector 173d satisfy at least one of the following: the area of ​​the end face of the first sub-connector 171d facing away from the second sub-connector 172d is larger than the area of ​​the end face of the first sub-connector 171d facing the second sub-connector 172d; the area of ​​the end face of the third sub-connector 173d facing away from the second sub-connector 172d is larger than the area of ​​the end face of the third sub-connector 173d facing the second sub-connector 172d.

[0123] In an optional embodiment, the first sub-connector 171d, the second sub-connector 172d, and the third sub-connector 173d satisfy at least one of the following conditions: the end surface of the first sub-connector 171d facing the second sub-connector 172d coincides with the end surface of the second sub-connector 172d facing the first sub-connector 171d; and the end surface of the third sub-connector 173d facing the second sub-connector 172d coincides with the end surface of the second sub-connector 172d facing the third sub-connector 173d. As shown in FIG5 , the end surface of the first sub-connector 171d facing the second sub-connector 172d coincides with the end surface of the second sub-connector 172d facing the first sub-connector 171d, and the end surface of the third sub-connector 173d facing the second sub-connector 172d coincides with the end surface of the second sub-connector 172d facing the third sub-connector 173d.

[0124] In an optional embodiment, the first sub-connector 171d and the third sub-connector 173d satisfy at least one of the following conditions: the angle β1 between the side surface of the first sub-connector 171d and the end surface of the first sub-connector 171d facing the second sub-connector 172d is an obtuse angle; and the angle β2 between the side surface of the third sub-connector 173d and the end surface of the third sub-connector 173d facing the second sub-connector 172d is an obtuse angle. This can improve the smoothness of the process for preparing the first sub-connector 171d and the process for preparing the third sub-connector 173d, and improve the connection strength between the sub-conductive connector 170d and the first conductive connector 170a, as well as the connection strength between the sub-conductive connector 170d and the second conductive connector 170b.

[0125] In an optional embodiment, the first sub-connector 171d and the third sub-connector 173d satisfy at least one of the following: an angle β1 between a side surface of the first sub-connector 171d and an end surface of the first sub-connector 171d facing the second sub-connector 172d is greater than 90 degrees and less than or equal to 150 degrees; and an angle β2 between a side surface of the third sub-connector 173d and an end surface of the third sub-connector 173d facing the second sub-connector 172d is greater than 90 degrees and less than or equal to 150 degrees. For example, β1 is 95 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees, or 150 degrees, and β2 is 95 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees, or 150 degrees.

[0126] In an optional embodiment, the first sub-connector 171d, the second sub-connector 172d, and the third sub-connector 173d are integrally formed. Thus, the first sub-connector 171d and the second sub-connector 172d are bonded by atomic bonding, and the third sub-connector 173d and the second sub-connector 172d are bonded by atomic bonding. The bonding strength between the first sub-connector 171d and the second sub-connector 172d is relatively high, and the bonding strength between the third sub-connector 173d and the second sub-connector 172d is relatively high. This makes it difficult for the first sub-connector 171d and the second sub-connector 172d to be pulled apart, and the third sub-connector 173d and the second sub-connector 172d to be pulled apart, thereby improving reliability.

[0127] For other descriptions about the circuit board 500, please refer to the relevant descriptions of the circuit board 400, which will not be repeated here.

[0128] The above is an introduction to the circuit board provided by this application. The following describes an embodiment of the method of this application.

[0129] FIG6 is a flow chart of a method for manufacturing a circuit board according to an embodiment of the present application. The method for manufacturing a circuit board can be used to manufacture the circuit board 400 shown in FIG4 and / or the circuit board 500 shown in FIG5.

[0130] 6 , the preparation method includes the following steps S601 to S602 .

[0131] S601. Form a first circuit board unit, a first conductive layer, an adhesive layer, and a second circuit board unit that are stacked in sequence.

[0132] 7 , a first circuit board unit A1, a first conductive layer 110, an adhesive layer C1, and a second circuit board unit B1 are sequentially stacked. The first conductive layer 110 is located on the surface of the first circuit board unit A1, and the second circuit board unit B1 is bonded to the first conductive layer 110 via the adhesive layer C1.

[0133] The first circuit board unit A1 includes one first unit or multiple stacked first units, each of which includes a first insulating base layer 100 and a second conductive layer 120. In any first unit, the second conductive layer 120 is located on the side of the first insulating base layer 100 facing away from the first conductive layer 110. FIG7 illustrates the example of a first circuit board unit A1 including one first unit.

[0134] The second circuit board unit B1 includes one second unit or multiple stacked second units, each of which includes a stacked second insulating base layer 130 and a third conductive layer 140. In any second unit, the third conductive layer 140 is located on the side of the second insulating base layer 130 facing away from the first conductive layer 110. FIG7 illustrates an example of a second circuit board unit B1 including one second unit.

[0135] S602. A first conductive connector is formed that passes through the first circuit board unit, a second conductive connector passes through the second circuit board unit and the adhesive layer, and a third conductive connector passes through the first conductive layer. The third conductive connector is connected to the first conductive connector and the second conductive connector, respectively. The bonding strength between the first conductive connector and the third conductive connector is greater than the bonding strength between the first conductive connector and the first conductive layer, and the bonding strength between the second conductive connector and the third conductive connector is greater than the bonding strength between the second conductive connector and the first conductive layer.

[0136] In an optional embodiment, a first hole is formed through the first circuit board unit; a second hole is formed through the second circuit board unit and the adhesive layer; and a third hole is formed through the first conductive layer, the third hole being connected to the first hole and the second hole, respectively. A first conductive connector is formed in the first hole, a second conductive connector is formed in the second hole, and a third conductive connector is formed in the third hole.

[0137] 8 , a first hole G1 is formed through the first circuit board unit A1 . For example, the first hole G1 is formed through the first circuit board unit A1 by a laser drilling process.

[0138] The width of the opening surface of the first hole G1 facing away from the first conductive layer 110 is greater than the width of the opening surface of the first hole G1 facing the first conductive layer 110. The area of ​​the opening surface of the first hole G1 facing away from the first conductive layer 110 is greater than the area of ​​the opening surface of the first hole G1 facing the first conductive layer 110.

[0139] The shape of the opening surface of the first hole G1 away from the first conductive layer 110 is circular, elliptical, strip-shaped or irregular. There is no limitation on the shape of the opening surface of the first hole G1 away from the first conductive layer 110.

[0140] The angle δ1 between the side surface of the first hole G1 and the opening surface of the first hole G1 facing the first conductive layer 110 is a right angle or an obtuse angle. FIG8 uses δ1 as an example of an obtuse angle. For example, δ1 is greater than or equal to 90 degrees and less than or equal to 140 degrees. It should be noted that in other embodiments, there is no limitation on the angle δ1 between the side surface of the first hole G1 and the opening surface of the first hole G1 facing the first conductive layer 110.

[0141] The number of the first holes G1 is one or more, and FIG8 takes one first hole G1 as an example.

[0142] 9 , a second hole G2 is formed through the second circuit board unit B1 and the adhesive layer C1. For example, the second hole G2 is formed through the second circuit board unit B1 and the adhesive layer C1 by a laser drilling process.

[0143] The width of the opening surface of the second hole G2 facing away from the first conductive layer 110 is greater than the width of the opening surface of the second hole G2 facing the first conductive layer 110. The area of ​​the opening surface of the second hole G2 facing away from the first conductive layer 110 is greater than the area of ​​the opening surface of the second hole G2 facing the first conductive layer 110.

[0144] The shape of the opening surface of the second hole G2 away from the first conductive layer 110 is circular, elliptical, strip-shaped or irregular. There is no limitation on the shape of the opening surface of the second hole G2 away from the first conductive layer 110.

[0145] The angle δ2 between the side surface of the second hole G2 and the opening surface of the second hole G2 facing the first conductive layer 110 is a right angle or an obtuse angle. FIG9 uses δ2 as an example of an obtuse angle. For example, δ2 is greater than or equal to 90 degrees and less than or equal to 140 degrees. It should be noted that in other embodiments, there is no limitation on the angle δ2 between the side surface of the second hole G2 and the opening surface of the second hole G2 facing the first conductive layer 110.

[0146] The number of the second holes G2 is one or more. FIG9 takes the number of the second hole G2 as one as an example. The second holes G2 correspond one to one with the first holes G1.

[0147] The present embodiment of the present application uses the example of forming the first hole G1 first and then the second hole G2. In other embodiments, the second hole G2 is formed first, and then the first hole G1 is formed. In other embodiments, the first hole G1 and the second hole G2 are formed simultaneously, but this embodiment of the present application is not limited to this.

[0148] After forming the first hole G1 and the second hole G2, referring to Figure 10, a third hole G3 is formed penetrating the first conductive layer 110. For example, the third hole G3 penetrating the first conductive layer 110 is formed by a laser drilling process.

[0149] The third hole G3 is connected to the first hole G1 and the second hole G2, respectively. The first hole G1, the second hole G2, and the third hole G3 satisfy at least one of the following conditions: the side surface of the third hole G3 is discontinuous with the side surface of the first hole G1; the side surface of the third hole G3 is discontinuous with the side surface of the second hole G2. For example, the side surface of the third hole G3 is discontinuous with the side surface of the first hole G1, and the side surface of the third hole G3 is discontinuous with the side surface of the second hole G2.

[0150] In an optional embodiment, the first hole G1, the second hole G2, and the third hole G3 further satisfy at least one of the following conditions: the area of ​​the opening surface of the first hole G1 facing away from the third hole G3 is greater than the area of ​​the opening surface of the first hole G1 facing the third hole G3; the area of ​​the opening surface of the second hole G2 facing away from the third hole G3 is greater than the area of ​​the opening surface of the second hole G2 facing the third hole G3; the area of ​​the opening surface of the third hole G3 facing the first hole G1 is not greater than the area of ​​the opening surface of the first hole G1 facing the third hole G3; and the area of ​​the opening surface of the third hole G3 facing the second hole G2 is not greater than the area of ​​the opening surface of the second hole G2 facing the third hole G3. For example, the area of ​​the opening surface of the third hole G3 facing the first hole G1 is smaller than the area of ​​the opening surface of the first hole G1 facing the third hole G3, and the area of ​​the opening surface of the third hole G3 facing the second hole G2 is smaller than the area of ​​the opening surface of the second hole G2 facing the third hole G3.

[0151] In an optional embodiment, the first hole G1, the second hole G2 and the third hole G3 also satisfy at least one of the following: the edge of the opening surface of the first hole G1 facing the third hole G3 does not overlap with the edge of the opening surface of the third hole G3 facing the first hole G1; the edge of the opening surface of the second hole G2 facing the third hole G3 does not overlap with the edge of the opening surface of the third hole G3 facing the second hole G2.

[0152] In an optional embodiment, the first hole G1, the second hole G2, and the third hole G3 further satisfy at least one of the following conditions: a lateral distance x1 between the outer edge of the opening surface of the first hole G1 facing the third hole G3 and the outer edge of the opening surface of the third hole G3 facing the first hole G1 is less than 10 μm; and a lateral distance x2 between the outer edge of the opening surface of the second hole G2 facing the third hole G3 and the outer edge of the opening surface of the third hole G3 facing the second hole G2 is less than 10 μm. In an optional embodiment, the third hole G3 includes a single sub-hole extending through the first conductive layer 110 or a plurality of sub-holes extending through the first conductive layer 110 and spaced apart. If the third hole G3 includes a single sub-hole, the single sub-hole is the third hole G3. When the third hole G3 includes multiple sub-holes, the outer edge of the opening surface of the third hole G3 facing the first hole G1 refers to: the outer edge of the opening surface of the third hole G3 facing the first hole G1 as a whole; the outer edge of the opening surface of the third hole G3 facing the second hole G2 refers to: the outer edge of the opening surface of the third hole G3 facing the second hole G2 as a whole.

[0153] In an optional embodiment, the third hole G3 includes a sub-hole penetrating the first conductive layer 110 or a plurality of sub-holes penetrating the first conductive layer 110 and spaced apart from each other. Forming the third hole G3 penetrating the first conductive layer 110 includes forming a sub-hole G30 penetrating the first conductive layer 110 or a plurality of sub-holes G30 penetrating the first conductive layer 110 and spaced apart from each other, each sub-hole G30 being connected to the first hole G1 and the second hole G2, respectively. FIG. 10 illustrates a third hole G3 including only one sub-hole G30; this sub-hole G30 is the third hole G3.

[0154] In an optional embodiment, the shapes of the various cross sections of the sub-holes G30 in a direction perpendicular to the thickness of the first conductive layer 110 are consistent, and the areas of the various cross sections of the sub-holes G30 in a direction perpendicular to the thickness of the first conductive layer 110 are consistent. In other embodiments, the shapes and / or areas of the sub-holes G30 in a direction perpendicular to the thickness of the first conductive layer 110 are different.

[0155] The shape of the opening surface of the sub-hole G30 facing the first hole G1 is circular, elliptical, elongated, or irregular. The shape of the opening surface of the sub-hole G30 facing the second hole G2 is circular, elliptical, elongated, or irregular. In this embodiment of the application, the shape of the opening surface of the sub-hole G30 facing the first hole G1 is circular, and the shape of the opening surface of the sub-hole G30 facing the second hole G2 is circular as an example.

[0156] Figure 11 is a top view of the second hole G2 shown in Figure 10 . The shape of the opening surface G21 of the second hole G2 facing the third hole G3, the shape of the opening surface G22 of the second hole G2 facing away from the third hole G3, and the shape of the opening surface of the sub-hole G30 facing the second hole G2 are all circular, with w4 being the diameter of the opening surface G21. The shape of the opening surface G21 of the first hole G1 facing the third hole G3, the shape of the opening surface of the first hole G1 facing away from the third hole G3, and the shape of the opening surface of the sub-hole G30 facing the first hole G1 are not further illustrated.

[0157] In an optional embodiment, the side surface of the third hole G3 is discontinuous with the side surface of the first hole G1, and the side surface of the third hole G3 is discontinuous with the side surface of the second hole G2. When the third hole G3 includes a sub-hole G30, the side surface of the third hole G3 is the side surface of the sub-hole G30. When the third hole G3 includes a plurality of spaced sub-holes G30, the side surface of the third hole G3 includes the side surface of each of the plurality of sub-holes G30, the side surface of each sub-hole G30 is discontinuous with the side surface of the first hole G1, and the side surface of each sub-hole G30 is discontinuous with the side surface of the second hole G2. In other embodiments, a portion of the side surface of the third hole G3 is continuous with the side surface of the first hole G1, and another portion of the side surface of the third hole G3 is discontinuous with the side surface of the first hole G1. In other embodiments, a portion of the side surface of the third hole G3 is continuous with the side surface of the second hole G2, and another portion of the side surface of the third hole G3 is discontinuous with the side surface of the second hole G2. For example, the third hole G3 includes a plurality of spaced sub-holes G30, the sides of some sub-holes G30 being continuous with the sides of the first hole G1, while the sides of other sub-holes G30 being discontinuous with the sides of the first hole G1; the sides of some sub-holes G30 being continuous with the sides of the second hole G2, while the sides of other sub-holes G30 being discontinuous with the sides of the second hole G2.

[0158] In an optional embodiment, the width w1 of the opening surface of the sub-hole G30 facing the first hole G1 is smaller than the width w2 of the opening surface of the first hole G1 facing the sub-hole G30, and the width w3 of the opening surface of the sub-hole G30 facing the second hole G2 is smaller than the width w4 of the opening surface of the second hole G2 facing the sub-hole G30.

[0159] In one embodiment, the width w1 of the opening surface of the sub-hole G30 facing the first hole G1 is 20 μm to 50 μm, and / or the width w3 of the opening surface of the sub-hole G30 facing the second hole G2 is 20 μm to 50 μm. If the width w1 of the opening surface of the sub-hole G30 facing the first hole G1 is too large, and the width w3 of the opening surface of the sub-hole G30 facing the second hole G2 is too large, the material used to form the sub-conductive connector may collapse on the side of the sub-hole G30 during the subsequent electroplating or chemical plating process to form a pit in the sub-conductive connector, resulting in poor filling effect in the sub-hole G30. If the width w1 of the opening surface of the sub-hole G30 facing the first hole G1 is too small, and the width w3 of the opening surface of the sub-hole G30 facing the second hole G2 is too small, the contact surface between the sub-conductive connector subsequently formed in the sub-hole G30 and the first conductive connector formed in the first hole G1 will be smaller, and the contact surface between the sub-conductive connector subsequently formed in the sub-hole G30 and the second conductive connector formed in the second hole G2 will be smaller, which will in turn lead to a smaller bonding force between the first conductive connector and the sub-conductive connector, and a smaller bonding force between the second conductive connector and the sub-conductive connector, affecting reliability.

[0160] After forming the first hole G1, the second hole G2, and the third hole G3, a liquid medicine can be sprayed into the first hole G1, the second hole G2, and the third hole G3 to remove the material debris (such as residual glue) remaining on the side surfaces of the first hole G1, the second hole G2, and the third hole G3. Figure 12 is a schematic diagram of removing the material debris remaining on the side surfaces of the first hole G1, the second hole G2, and the third hole G3 provided in an embodiment of the present application. As shown in Figure 12, the liquid medicine is sprayed into the first hole G1, the second hole G2, and the third hole G3 from the side where the second hole G2 is located, so that the residual glue on the side surfaces of the first hole G1, the second hole G2, and the third hole G3 is dissolved in the liquid medicine, thereby achieving the effect of removing the residual glue. Since the first hole G1, the second hole G2, and the third hole G3 are connected, the "pool effect" can be avoided. The liquid does not accumulate in the first, second, and third holes G1, G2, and G3. The liquid has high fluidity within these holes, resulting in a good flushing effect. Even with a short duration of spraying the liquid into the first, second, and third holes G1, G2, and G3, residual material debris on the sides of the first, second, and third holes G1, G2, and G3 can be fully removed. In one embodiment, the liquid is sprayed into the first, second, and third holes G1, G2, and G3 for 10 to 20 minutes.

[0161] After forming the first hole G1, the second hole G2, and the third hole G3, for example, after removing any remaining material debris from the sides of the first hole G1, the second hole G2, and the third hole G3, referring to FIG. 13 , a first conductive connector 170a is formed in the first hole G1, a second conductive connector 170b is formed in the second hole G2, and a third conductive connector 170c is formed in the third hole G3. In an alternative embodiment, the first conductive connector 170a is formed in the first hole G1, the second conductive connector 170b is formed in the second hole G2, and the third conductive connector 170c is formed in the third hole G3 through electroplating or chemical plating. In an alternative embodiment, the first conductive connector 170a is formed in the first hole G1, the second conductive connector 170b is formed in the second hole G2, and the third conductive connector 170c is formed in the third hole G3 through the same process. The first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c are integrally formed.

[0162] In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b and the third conductive connector 170c satisfy at least one of the following: the side of the third conductive connector 170c is discontinuous with the side of the first conductive connector 170a; the side of the third conductive connector 170c is discontinuous with the side of the second conductive connector 170b.

[0163] In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b and the third conductive connector 170c satisfy at least one of the following: the area of ​​the end surface of the first conductive connector 170a facing away from the third conductive connector 170c is greater than the area of ​​the end surface of the first conductive connector 170a facing the third conductive connector 170c; the area of ​​the end surface of the second conductive connector 170b facing away from the third conductive connector 170c is greater than the area of ​​the end surface of the second conductive connector 170b facing the third conductive connector 170c; the area of ​​the end surface of the third conductive connector 170c facing the first conductive connector 170a is not greater than the area of ​​the end surface of the first conductive connector 170a facing the third conductive connector 170c; the area of ​​the end surface of the third conductive connector 170c facing the second conductive connector 170b is not greater than the area of ​​the end surface of the second conductive connector 170b facing the third conductive connector 170c.

[0164] In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b and the third conductive connector 170c satisfy at least one of the following: the edge of the end face of the first conductive connector 170a facing the third conductive connector 170c does not overlap with the edge of the end face of the third conductive connector 170c facing the first conductive connector 170a; the edge of the end face of the second conductive connector 170b facing the third conductive connector 170c does not overlap with the edge of the end face of the third conductive connector 170c facing the second conductive connector 170b.

[0165] In an optional embodiment, the first conductive connector 170a, the second conductive connector 170b and the third conductive connector 170c satisfy at least one of the following: the lateral distance x1 between the outer edge of the end surface of the first conductive connector 170a facing the third conductive connector 170c and the outer edge of the end surface of the third conductive connector 170c facing the first conductive connector 170a is less than 10 μm; the lateral distance x2 between the outer edge of the end surface of the second conductive connector 170b facing the third conductive connector 170c and the outer edge of the end surface of the third conductive connector 170c facing the second conductive connector 170b is less than 10 μm.

[0166] In an optional embodiment, the third hole G3 includes a sub-hole G30 passing through the first conductive layer 110 or a plurality of sub-holes G30 passing through the first conductive layer 110 and spaced apart, each sub-hole G30 being connected to the first hole G1 and the second hole G2 respectively, and the third conductive connector 170c includes a sub-conductive connector 170d passing through the first conductive layer 110 or a plurality of sub-conductive connectors 170d passing through the first conductive layer 110 and spaced apart, each sub-conductive connector 170d being located in a sub-hole G30, each sub-conductive connector 170d being connected to the first conductive connector 170a and the second conductive connector 170b respectively, and a sub-conductive connector 170d is formed in each sub-hole G30 to form a third conductive connector 170c in the third hole G3.

[0167] In the embodiment of the present application, after removing residual material debris (e.g., adhesive residue) from the side surfaces of the first, second, and third holes G1, G2, and G3, a first conductive connector 170a is formed in the first hole G1, a second conductive connector 170b is formed in the second hole G2, and a third conductive connector 170c is formed in the third hole G3. Because the residual material debris from the side surfaces of the first, second, and third holes G1, G2, and G3 can be fully removed even with a relatively short time for spraying the chemical solution into the first, second, and third holes G3, the coating process for forming the first conductive connector 170a in the first hole G1, the second conductive connector 170b in the second hole G2, and the third conductive connector 170c in the third hole G3 all achieve good results, resulting in good conductivity between the first and third conductive connectors 170a, 170c, and the second and third conductive connectors 170b, 170c. Because the time for spraying the chemical solution into the first, second, and third holes G1, G2, and G3 is relatively short, the chemical solution has minimal loss on the portions of the first conductive layer 110 exposed to the first, second, and third holes G1, G2, and G3. This reduces the thickness of the portion of the first conductive layer 110 between the first and second conductive connectors 170a, 170b, thereby reducing the probability of cracks in the portion of the first conductive layer 110 between the first and second conductive connectors 170a, 170b due to stretching by the adhesive layer C1. In one embodiment, the thickness of the portion of the first conductive layer 110 between the first and second conductive connectors 170a, 170b is between 6 μm and 10 μm.

[0168] In an optional embodiment, as shown in Figure 13, the preparation method also includes: forming a first solder pad 150a on the side of the second circuit board unit B1 away from the first circuit board unit A1, and the first solder pad 150a is connected to the second conductive connector 170b; forming a second solder pad 150b on the side of the first circuit board unit A1 away from the second circuit board unit B1, and the second solder pad 150b is connected to the first conductive connector 170a.

[0169] In an optional embodiment, the first pad 150a and the second conductive connector 170b are integrally formed, and the first pad 150a and the second conductive connector 170b are formed through the same process. The second pad 150b and the first conductive connector 170a are integrally formed, and the second pad 150b and the first conductive connector 170a are formed through the same process. Because the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c are formed through the same process, the first conductive connector 170a, the second conductive connector 170b, the third conductive connector 170c, the first pad 150a, and the second pad 150b are formed through the same process. Therefore, the first pad 150a and the second pad 150b are formed during the process of forming the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c.

[0170] In an optional embodiment, referring to FIG. 4 , after forming first solder pad 150a, solder layer 180 is formed on the side of first solder pad 150a facing away from second circuit board unit B1; and electronic component 190 is formed on the side of solder layer 180 facing away from first solder pad 150a. In a specific embodiment, after forming first solder pad 150a, a stacked second insulating protective film 162 and second electromagnetic shielding layer 163 are formed on the side of second circuit board unit B1 facing away from first circuit board unit A1. Second insulating protective film 162 covers second conductive connector 170b and first solder pad 150a, and a solder pad hole is formed through second insulating protective film 162 and second electromagnetic shielding layer 163. Solder layer 180 is formed in the solder pad hole. For example, solder paste is applied to the solder pad hole to form solder layer 180.

[0171] In an optional embodiment, please refer to Figure 4. After the second solder pad 150b is formed, a stacked first insulating protective film 160 and a first electromagnetic shielding layer 161 are formed on the side of the first circuit board unit A1 facing away from the second circuit board unit B1, and the first insulating protective film 160 covers the first conductive connector 170a and the second solder pad 150b.

[0172] In an optional embodiment, the third hole G3 includes a sub-hole G30 that extends through the first conductive layer 110, or a plurality of sub-holes G30 that extend through the first conductive layer 110 and are spaced apart from each other. The sub-hole G30 includes a first groove G31, a second groove G32, and a third groove G33 that are sequentially connected in the thickness direction of the first conductive layer 110. The sub-conductive connector 170d includes a first sub-connector 171d, a second sub-connector 172d, and a third sub-connector 173d that are sequentially connected in the thickness direction of the first conductive layer 110. The first sub-connector 171d is located in the first groove G31, the second sub-connector 172d is located in the second groove G32, and the third sub-connector 173d is located in the third groove G33.

[0173] After forming the first hole G1 and the second hole G2, a third hole G3 is formed that penetrates the first conductive layer 110. Specifically, this includes forming a sub-hole G30 that penetrates the first conductive layer 110 or a plurality of sub-holes G30 that penetrate the first conductive layer 110 and are spaced apart. The process of forming any sub-hole G30 that penetrates the first conductive layer 110 can be shown in Figures 14 to 16. As shown in Figure 14, based on Figure 9, a first groove G31 is formed on the first conductive layer 110 through the exposed portion of the first hole G1. The area of ​​the opening surface of the first groove G31 (the side of the first groove G31 facing the first hole G1) is larger than the area of ​​the bottom surface of the first groove G31 (the side of the first groove G31 facing away from the first hole G1). As shown in FIG15 , a third groove G33 is formed in the portion of the first conductive layer 110 exposed by the second hole G2. The third groove G33 corresponds to the first groove G31. The area of ​​the opening surface of the third groove G33 (the side of the third groove G33 facing the second hole G2) is larger than the area of ​​the bottom surface of the third groove G33 (the side of the third groove G33 facing away from the second hole G2). A portion of the first conductive layer 110 lies between the third groove G33 and the first groove G31. In other words, a portion of the first conductive layer 110 lies between the bottom surface of the third groove G33 and the bottom surface of the first groove G31, and the third groove G33 and the first groove G31 are not connected. After the first groove G31 and the third groove G33 are formed, as shown in Figure 16, a second groove G32 is formed on the first conductive layer 110 at a position between the third groove G33 and the first groove G31. The second groove G32 is connected to the first groove G31 and the third groove G33 respectively. The first groove G31, the second groove G32 and the third groove G33 are connected to form a sub-hole G30.

[0174] The present embodiment of the present application uses the example of forming the first groove G31 first and then the third groove G33. In other embodiments, the third groove G33 is formed first and then the first groove G31. In other embodiments, the first groove G31 and the third groove G33 are formed simultaneously. This embodiment of the present application is not limited to this.

[0175] The first groove G31 , the second groove G32 , and the third groove G33 may be formed by a laser drilling process.

[0176] The first groove G31 and the third groove G33 satisfy at least one of the following conditions: the angle between the side of the first groove G31 and the bottom of the first groove G31 (i.e., the side of the first groove G31 facing the second groove G32) is an obtuse angle; the angle between the side of the third groove G33 and the bottom of the third groove G33 (i.e., the side of the third groove G33 facing the second groove G32) is an obtuse angle. For example, the angle between the side of the first groove G31 and the bottom of the first groove G31 is greater than 90 degrees and less than or equal to 150 degrees; the angle between the side of the third groove G33 and the bottom of the third groove G33 is greater than 90 degrees and less than or equal to 150 degrees. The topography of the side of the first groove G31 is achieved by adjusting the laser spot and the laser focus position during the laser drilling process. The topography of the side of the third groove G33 is achieved by adjusting the laser spot and the laser focus position during the laser drilling process. The side of the groove is also the surface of the sidewall of the groove, also known as the sidewall surface or sidewall.

[0177] After forming the first hole G1, the second hole G2, and the third hole G3 (in this embodiment, after forming the first hole G1, the second hole G2, the first groove G31, the second groove G32, and the third groove G33), a chemical solution can be sprayed into the first hole G1, the second hole G2, the first groove G31, the second groove G32, and the third groove G33 to remove material debris (e.g., residual glue) remaining on the sides of the first hole G1, the second hole G2, the first groove G31, the second groove G32, and the third groove G33. The material debris removal process takes 10 to 20 minutes. Since the angle between the side surface of the first groove G31 and the bottom surface of the first groove G31 (that is, the side of the first groove G31 facing the second groove G32) is an obtuse angle, and the angle between the side surface of the third groove G33 and the bottom surface of the third groove G33 (that is, the side of the third groove G33 facing the second groove G32) is an obtuse angle, therefore, during the process of removing material debris, the fluidity of the liquid medicine in the first hole G1, the second hole G2, the first groove G31, the second groove G32 and the third groove G33 is relatively high, and the loss of the thickness of the first conductive layer 110 of the liquid medicine can be reduced while fully removing the material debris.

[0178] After forming the first hole G1, the second hole G2, and the third hole G3, for example, after removing any remaining material debris from the sides of the first hole G1, the second hole G2, and the third hole G3, referring to FIG17 , a first conductive connector 170 a is formed in the first hole G1, a second conductive connector 170 b is formed in the second hole G2, and a third conductive connector 170 c is formed in the third hole G3. In a specific embodiment, the third hole G3 includes one sub-hole G30 or a plurality of spaced sub-holes G30, with one sub-conductive connector 170 d formed in each sub-hole G30. Each sub-hole G30 includes a first groove G31, a second groove G32, and a third groove G33 that are sequentially connected in the thickness direction of the first conductive layer 110. Forming a sub-conductive connector 170d in any sub-hole G30 includes: forming a first sub-connector 171d in the first groove G31; forming a second sub-connector 172d in the second groove G32; and forming a third sub-connector 173d in the third groove G33. The first sub-connector 171d, the second sub-connector 172d, and the third sub-connector 173d are sequentially connected to form the sub-conductive connector 170d. Figures 16 and 17 illustrate the example of a third hole G3 including one sub-hole G30.

[0179] In an alternative embodiment, the first conductive connector 170a, the second conductive connector 170b, the first sub-connector 171d, the second sub-connector 172d, and the third sub-connector 173d are formed in the same process. The first conductive connector 170a, the second conductive connector 170b, the first sub-connector 171d, the second sub-connector 172d, and the third sub-connector 173d are an integral structure. In an alternative embodiment, the first conductive connector 170a, the second conductive connector 170b, the first sub-connector 171d, the second sub-connector 172d, and the third sub-connector 173d are formed by electroplating or chemical plating.

[0180] Since the angle between the side surface of the first groove G31 and the bottom surface of the first groove G31 (that is, the side of the first groove G31 facing the second groove G32) is an obtuse angle, and the angle between the side surface of the third groove G33 and the bottom surface of the third groove G33 (that is, the side of the third groove G33 facing the second groove G32) is an obtuse angle, therefore, the angle between the side surface of the first sub-connector 171d and the end surface of the first sub-connector 171d facing the second sub-connector 172d is an obtuse angle, and the angle between the side surface of the third sub-connector 173d and the end surface of the third sub-connector 173d facing the second sub-connector 172d is an obtuse angle. For example, the angle between the side surface of the first groove G31 and the bottom surface of the first groove G31 is greater than 90 degrees and less than or equal to 150 degrees, and / or the angle between the side surface of the third groove G33 and the bottom surface of the third groove G33 is greater than 90 degrees and less than or equal to 150 degrees, so that the angle between the side surface of the first sub-connector 171d and the end surface of the first sub-connector 171d facing the second sub-connector 172d is greater than 90 degrees and less than or equal to 150 degrees, and / or the angle between the side surface of the third sub-connector 173d and the end surface of the third sub-connector 173d facing the second sub-connector 172d is greater than 90 degrees and less than or equal to 150 degrees. In one example, the angle between the side of the first groove G31 and the bottom of the first groove G31 is 95 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees or 150 degrees, and the angle between the side of the third groove G33 and the bottom of the third groove G33 is 95 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees or 150 degrees. The angle between the end faces of the sub-connector 171d facing the second sub-connector 172d is 95 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees or 150 degrees, and the angle between the side of the third sub-connector 173d and the end face of the third sub-connector 173d facing the second sub-connector 172d is 95 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees or 150 degrees. Since the angle between the side surface of the first groove G31 and the bottom surface of the first groove G31 (that is, the side of the first groove G31 facing the second groove G32) is an obtuse angle, and the angle between the side surface of the third groove G33 and the bottom surface of the third groove G33 (that is, the side of the third groove G33 facing the second groove G32) is an obtuse angle, the smoothness of the process for preparing the first sub-connector 171d and the smoothness of the process for preparing the third sub-connector 173d can be improved, the connection strength between the sub-conductive connector 170d and the first conductive connector 170a can be improved, and the connection strength between the sub-conductive connector 170d and the second conductive connector 170b can be improved.

[0181] In an alternative embodiment, as shown in FIG17 , during the formation of the first conductive connector 170a, the second conductive connector 170b, and the third conductive connector 170c, a first soldering pad 150a is formed on a side of the second circuit board unit B1 facing away from the first circuit board unit A1, and a second soldering pad 150b is formed on a side of the first circuit board unit A1 facing away from the second circuit board unit B1. The first soldering pad 150a is connected to the second conductive connector 170b, and the second soldering pad 150b is connected to the first conductive connector 170a. For example, the first soldering pad 150a and the second conductive connector 170b are integrally formed, and the second soldering pad 150b and the first conductive connector 170a are integrally formed.

[0182] In an alternative embodiment, referring to FIG. 5 , after forming first solder pad 150a, solder layer 180 is formed on the side of first solder pad 150a facing away from second circuit board unit B1; and electronic component 190 is formed on the side of solder layer 180 facing away from first solder pad 150a. In a specific embodiment, after forming first solder pad 150a, a stacked second insulating protective film 162 and second electromagnetic shielding layer 163 are formed on the side of second circuit board unit B1 facing away from first circuit board unit A1. Second insulating protective film 162 covers second conductive connector 170b and first solder pad 150a, and a solder pad hole is formed through second insulating protective film 162 and second electromagnetic shielding layer 163. Solder layer 180 is formed in the solder pad hole. For example, solder paste is applied to the solder pad hole to form solder layer 180.

[0183] In an optional embodiment, referring to Figure 5, after the second solder pad 150b is formed, a stacked first insulating protective film 160 and a first electromagnetic shielding layer 161 are formed on the side of the first circuit board unit A1 facing away from the second circuit board unit B1, and the first insulating protective film 160 covers the first conductive connector 170a and the second solder pad 150b.

[0184] The embodiment of the present application further provides a display module, comprising: a display panel and the circuit board of the above embodiment. The circuit board is electrically connected to the display panel.

[0185] An embodiment of the present application further provides a display device, comprising the display module of the above embodiment.

[0186] Since the circuit board provided in the embodiment of the present application has high reliability, the display module including the circuit board has high reliability, and thus the display device including the display module has high reliability.

[0187] The display device can be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator, or the like.

[0188] Other essential components of the display device should be understood by those skilled in the art and will not be described in detail here, nor should they be construed as limitations on this application.

[0189] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. A circuit board, comprising: A first circuit board unit, a first conductive layer, an adhesive layer, and a second circuit board unit are sequentially stacked; A first conductive connector penetrating through the first circuit board unit; A second conductive connector penetrating the second circuit board unit and the adhesive layer; A third conductive connector penetrating through the first conductive layer; The third conductive connector is connected to the first conductive connector and the second conductive connector respectively, the bonding strength between the first conductive connector and the third conductive connector is greater than the bonding strength between the first conductive connector and the first conductive layer, and the bonding strength between the second conductive connector and the third conductive connector is greater than the bonding strength between the second conductive connector and the first conductive layer.

2. The circuit board according to claim 1, wherein: The first conductive connector, the second conductive connector and the third conductive connector are an integrated structure.

3. The circuit board according to claim 1 or 2, wherein: The first conductive connector, the second conductive connector, and the third conductive connector satisfy at least one of the following: The side surface of the third conductive connector is discontinuous with the side surface of the first conductive connector; The side surface of the third conductive connector is discontinuous with the side surface of the second conductive connector.

4. The circuit board according to claim 3, wherein: The first conductive connector, the second conductive connector, and the third conductive connector satisfy at least one of the following: The area of ​​the end surface of the first conductive connector facing away from the third conductive connector is larger than the area of ​​the end surface of the first conductive connector facing the third conductive connector; The area of ​​the end surface of the second conductive connector facing away from the third conductive connector is larger than the area of ​​the end surface of the second conductive connector facing the third conductive connector; The area of ​​the end surface of the third conductive connector facing the first conductive connector is not greater than the area of ​​the end surface of the first conductive connector facing the third conductive connector; An area of ​​an end surface of the third conductive connector facing the second conductive connector is not greater than an area of ​​an end surface of the second conductive connector facing the third conductive connector.

5. The circuit board according to claim 4, wherein: The first conductive connector, the second conductive connector, and the third conductive connector satisfy at least one of the following: The edge of the end surface of the first conductive connector facing the third conductive connector does not overlap with the edge of the end surface of the third conductive connector facing the first conductive connector; An edge of an end surface of the second conductive connector facing the third conductive connector does not overlap with an edge of an end surface of the third conductive connector facing the second conductive connector.

6. The circuit board according to claim 5, wherein: The first conductive connector, the second conductive connector, and the third conductive connector satisfy at least one of the following: The lateral distance between the outer edge of the end surface of the first conductive connector facing the third conductive connector and the outer edge of the end surface of the third conductive connector facing the first conductive connector is less than 10 μm; A lateral distance between an outer edge of an end surface of the second conductive connector facing the third conductive connector and an outer edge of an end surface of the third conductive connector facing the second conductive connector is less than 10 μm.

7. The circuit board according to any one of claims 1 to 6, wherein: The third conductive connector includes one sub-conductive connector or a plurality of spaced sub-conductive connectors, and the sub-conductive connectors are connected to the first conductive connector and the second conductive connector respectively.

8. The circuit board according to claim 7, wherein: The sub-conductive connector satisfies at least one of the following: The width of the end surface of the sub-conductive connector facing the first conductive connector is 20 μm to 50 μm; The width of the end surface of the sub-conductive connector facing the second conductive connector is 20 μm to 50 μm.

9. The circuit board according to claim 7 or 8, wherein: The sub-conductive connector includes a first sub-connector, a second sub-connector, and a third sub-connector which are sequentially connected in the thickness direction of the first conductive layer, the first sub-connector is connected to the first conductive connector, the third sub-connector is connected to the second conductive connector, and the first sub-connector, the second sub-connector, and the third sub-connector satisfy at least one of the following: The area of ​​the end surface of the first sub-connector facing away from the second sub-connector is larger than the area of ​​the end surface of the first sub-connector facing the second sub-connector; The area of ​​the end surface of the third sub-connector facing away from the second sub-connector is larger than the area of ​​the end surface of the third sub-connector facing the second sub-connector.

10. The circuit board according to claim 9, wherein: The first subconnector, the second subconnector, and the third subconnector satisfy at least one of the following: The end surface of the first sub-connector facing the second sub-connector coincides with the end surface of the second sub-connector facing the first sub-connector; An end surface of the third sub-connector facing the second sub-connector coincides with an end surface of the second sub-connector facing the third sub-connector.

11. The circuit board according to claim 9 or 10, wherein: The first subconnector, the second subconnector, and the third subconnector satisfy at least one of the following: The angle between the side surface of the first sub-connector and the end surface of the first sub-connector facing the second sub-connector is an obtuse angle; An angle between a side surface of the third sub-connector and an end surface of the third sub-connector facing the second sub-connector is an obtuse angle.

12. The circuit board according to claim 11, wherein: The first subconnector, the second subconnector, and the third subconnector satisfy at least one of the following: The angle between the side surface of the first sub-connector and the end surface of the first sub-connector facing the second sub-connector is greater than 90 degrees and less than or equal to 150 degrees; An angle between a side surface of the third sub-connector and an end surface of the third sub-connector facing the second sub-connector is greater than 90 degrees and less than or equal to 150 degrees.

13. The circuit board according to any one of claims 9 to 12, wherein: The first sub-connector, the second sub-connector and the third sub-connector are an integrated structure.

14. The circuit board according to any one of claims 1 to 13, wherein: The angle between the side surface of the first conductive connector and the end surface of the first conductive connector facing the third conductive connector is an obtuse angle; An angle between a side surface of the second conductive connector and an end surface of the second conductive connector facing the third conductive connector is an obtuse angle.

15. The circuit board according to claim 14, wherein: The angle between the side surface of the first conductive connector and the end surface of the first conductive connector facing the third conductive connector is greater than or equal to 90 degrees and less than or equal to 140 degrees; An angle between a side surface of the second conductive connector and an end surface of the second conductive connector facing the third conductive connector is greater than or equal to 90 degrees and less than or equal to 140 degrees.

16. The circuit board according to any one of claims 1 to 15, wherein: The first circuit board unit includes one first unit or a plurality of stacked first units, wherein the first unit includes a stacked first insulating base layer and a second conductive layer; in any one of the first units, the second conductive layer is located on a side of the first insulating base layer away from the first conductive layer; The second circuit board unit includes one second unit or a plurality of stacked second units, wherein the second unit includes a stacked second insulating base layer and a third conductive layer; in any one of the second units, the third conductive layer is located on a side of the second insulating base layer away from the first conductive layer.

17. The circuit board according to any one of claims 1 to 16, wherein: The circuit board also includes: a first pad located on a side of the second circuit board unit facing away from the first circuit board unit, the first pad being connected to the second conductive connector; a welding layer located on a side of the first welding pad facing away from the second circuit board unit; The electronic component is located on a side of the soldering layer away from the first soldering pad.

18. The circuit board according to any one of claims 1 to 17, wherein: The circuit board is a flexible circuit board or a printed circuit board.

19. A method for preparing a circuit board, comprising: Forming a first circuit board unit, a first conductive layer, an adhesive layer, and a second circuit board unit stacked in sequence; A first conductive connector is formed that passes through the first circuit board unit, a second conductive connector passes through the second circuit board unit and the adhesive layer, and a third conductive connector passes through the first conductive layer. The third conductive connector is connected to the first conductive connector and the second conductive connector, respectively. The bonding strength between the first conductive connector and the third conductive connector is greater than the bonding strength between the first conductive connector and the first conductive layer, and the bonding strength between the second conductive connector and the third conductive connector is greater than the bonding strength between the second conductive connector and the first conductive layer.

20. The method according to claim 19, wherein: Forming a first conductive connector penetrating the first circuit board unit, a second conductive connector penetrating the second circuit board unit and the adhesive layer, and a third conductive connector penetrating the first conductive layer, comprising: forming a first hole penetrating the first circuit board unit; forming a second hole penetrating the second circuit board unit and the adhesive layer; forming a third hole penetrating through the first conductive layer, wherein the third hole is connected to the first hole and the second hole respectively; The first conductive connection body is formed in the first hole, the second conductive connection body is formed in the second hole, and the third conductive connection body is formed in the third hole.

21. The method according to claim 20, wherein: Forming a third hole penetrating the first conductive layer includes: forming a sub-hole penetrating the first conductive layer or a plurality of sub-holes penetrating the first conductive layer and spaced apart from each other, each of the sub-holes being connected to the first hole and the second hole respectively; Forming the third conductive connector in the third hole includes: forming a sub-conductive connector in each of the sub-holes.

22. The method according to claim 21, wherein: Forming any one of the sub-holes penetrating the first conductive layer comprises: forming a first groove on the first conductive layer at a portion exposed by the first hole, wherein an area of ​​an opening surface of the first groove is larger than an area of ​​a bottom surface of the first groove; forming a third groove on the first conductive layer at a portion exposed by the second hole, wherein an opening surface of the third groove has an area larger than a bottom surface of the third groove, and a portion of the first conductive layer is located between the third groove and the first groove; A second groove is formed on the first conductive layer at a position between the third groove and the first groove, wherein the second groove is connected to the first groove and the third groove respectively to form the sub-hole; Forming a sub-conductive connector in any of the sub-holes includes: forming a first sub-connector in the first groove, forming a second sub-connector in the second groove, and forming a third sub-connector in the third groove.

23. A display module, comprising: Display panel; The circuit board according to any one of claims 1 to 18; The circuit board is electrically connected to the display panel.

24. A display device, characterized in that: Includes the display module described in claim 23.

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