Method for manufacturing a circuit board, circuit board, circuit board assembly, and mobile terminal

Abstract

The present disclosure relates to a circuit board manufacturing method, a circuit board, a circuit board assembly and a mobile terminal. The circuit board manufacturing method comprises: laminating copper foil on both sides of an insulating substrate, etching a circuit pattern on the copper foil to form a core board; applying a solder mask layer on a first board surface of the core board and laminating a sheet structure on at least a second board surface of the core board to form a circuit board; and opening a mounting cavity on the circuit board from one side facing the first board surface to expose the solder mask layer. The electronic device can be mounted in the mounting cavity of the circuit board through the embodiment of the present disclosure.

Description

Technical Field

[0001] This disclosure relates to the field of mobile terminal technology, and in particular to a method for manufacturing a circuit board, a circuit board, a circuit board assembly, and a mobile terminal. Background Technology

[0002] As mobile devices become increasingly thinner, more and more of them are adopting ultra-thin stacking designs, further compressing the space available for PCB components. Furthermore, with the increasing functionality of mobile devices, the number of electronic devices that need to be housed on the PCB is also constantly increasing. Therefore, how to integrate more electronic components onto the PCB has become a pressing issue. Summary of the Invention

[0003] To overcome the problems existing in the related technologies, this disclosure provides a method for manufacturing a circuit board, a circuit board, a circuit board assembly, and a mobile terminal, which enables the installation of electronic devices in the mounting cavity of the circuit board.

[0004] According to a first aspect of the present disclosure, a method for manufacturing a circuit board is provided, the method comprising:

[0005] Copper foil is laminated onto both sides of an insulating substrate, and a circuit pattern is etched onto the copper foil to form a core board.

[0006] A solder resist layer is applied to the first surface of the core board, and a sheet structure is pressed onto at least the second surface of the core board to form a circuit board;

[0007] A mounting cavity is formed on the circuit board from the side facing the first panel to expose the solder resist layer.

[0008] In some embodiments, the preparation method further includes:

[0009] The solder resist layer is browned.

[0010] The protective layer is attached to the browned solder resist layer;

[0011] After the mounting cavity is opened, the protective layer is peeled off from the solder resist layer.

[0012] In some embodiments, the protective layer includes a peelable adhesive;

[0013] The preparation method further includes:

[0014] Install the guide plate between the peelable adhesive and the solder resist layer;

[0015] The method of creating a mounting cavity on the circuit board from the side facing the first plate includes:

[0016] From the side facing the first plate, a cut is made along the thickness direction of the circuit board to the guide plate, and the cut portion is removed from the circuit board to form the mounting cavity.

[0017] In some embodiments, the protective layer comprises a polyimide film;

[0018] The preparation method further includes:

[0019] After the polyimide film is peeled off, solder resist is applied within the mounting cavity of the circuit board.

[0020] In some embodiments, the preparation method further includes:

[0021] Before performing solder resist on the inside of the mounting cavity, solder resist is performed on the outside of the mounting cavity of the circuit board.

[0022] In some embodiments, performing solder resist within the mounting cavity of the circuit board includes:

[0023] Ink is sprayed into the mounting cavity using an electrostatic spraying process.

[0024] In some embodiments, the preparation method further includes:

[0025] Cut the solder resist layer outside the designated location and peel off the protective layer outside the designated location.

[0026] In some embodiments, the thickness of the prepreg layer between the bottom copper foil of the circuit board and the bottom of the mounting cavity is less than or equal to 150 micrometers;

[0027] And / or,

[0028] The depth of the mounting cavity is between 1 mm and 1.8 mm;

[0029] And / or,

[0030] The minimum distance between the exposed solder pads of the solder resist layer and the cavity wall of the mounting cavity is greater than or equal to 0.5 mm.

[0031] In some embodiments, the depth of the mounting cavity is positively correlated with the thickness of the circuit board.

[0032] According to a second aspect of the present disclosure, a circuit board is provided, comprising: being manufactured using the preparation method described in the first aspect above.

[0033] According to a third aspect of the present disclosure, a circuit board assembly is provided, comprising:

[0034] Multiple circuit boards stacked together;

[0035] The circuit boards having mounting cavities among the plurality of said circuit boards are manufactured using the preparation method described in the first aspect above.

[0036] In some embodiments, electronic devices are mounted on both sides of the mounting cavity of at least one of the circuit boards in the circuit board assembly along the thickness direction of the circuit board.

[0037] In some embodiments, the plurality of circuit boards include a first circuit board, a second circuit board, and a third circuit board that are stacked sequentially.

[0038] The second circuit board covers the opening of the mounting cavity of the first circuit board;

[0039] The third circuit board covers the opening of the mounting cavity of the second circuit board;

[0040] The electronic devices are mounted on both sides of the mounting cavity of the first circuit board along the thickness direction.

[0041] And / or,

[0042] The electronic devices are mounted on both sides of the mounting cavity of the second circuit board along the thickness direction.

[0043] According to a fourth aspect of the present disclosure, a mobile terminal is provided, comprising:

[0044] case;

[0045] The circuit board assembly as described in the second aspect above is disposed in the housing.

[0046] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects:

[0047] In this embodiment, a solder resist layer is applied to the first surface of the core board, and a circuit board is formed by laminating a sheet structure onto at least the second surface of the core board. A mounting cavity is formed on the circuit board from the side facing the first surface to expose the solder resist layer. In other words, this embodiment pre-applies the solder resist layer during the circuit board formation process and exposes the solder resist layer through the mounting cavity, enabling the mounting of electronic devices within the mounting cavity.

[0048] This not only makes the installation of electronic components on the circuit board more flexible, but also allows for the placement of more electronic components on the circuit board by installing them in the mounting cavity, thereby reducing the space occupied by the circuit board.

[0049] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0050] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0051] Figure 1 This is a flowchart illustrating a method for manufacturing a circuit board according to an exemplary embodiment.

[0052] Figure 2 This is a schematic diagram illustrating a mounting cavity on a 12-layer circuit board according to an exemplary embodiment.

[0053] Figure 3 This is a process flow diagram illustrating the fabrication of a circuit board having a mounting cavity according to an exemplary embodiment.

[0054] Figure 4 This is a schematic diagram of an electrostatic inkjet printer according to an exemplary embodiment.

[0055] Figure 5 This is a schematic diagram illustrating a mounting cavity on a circuit board with solder pads provided according to an exemplary embodiment.

[0056] Figure 6 This is a schematic diagram illustrating the arrangement of solder pads within a mounting cavity according to an exemplary embodiment.

[0057] Figure 7 This is a schematic diagram illustrating a method for fabricating a circuit board by bonding a peelable adhesive according to an exemplary embodiment.

[0058] Figure 8 This is a schematic diagram illustrating a method for fabricating a circuit board by laminating a PI film according to an exemplary embodiment.

[0059] Figure 9A This is a schematic diagram of a circuit board assembly according to an exemplary embodiment. Figure 1 .

[0060] Figure 9B This is a schematic diagram of a circuit board assembly according to an exemplary embodiment. Figure 2 .

[0061] Figure 10 This is a structural block diagram of a mobile terminal according to an exemplary embodiment. Detailed Implementation

[0062] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0063] This disclosure provides a method for manufacturing a circuit board. Figure 1 This is a flowchart illustrating a method for manufacturing a circuit board according to an exemplary embodiment. Figure 1 As shown, the method for manufacturing the circuit board includes the following steps:

[0064] Step 11: Press copper foil onto both sides of the insulating substrate and etch the circuit pattern onto the copper foil to form the core board;

[0065] Step 12: Apply a solder resist layer to the first surface of the core board, and press a sheet structure onto at least the second surface of the core board to form a circuit board;

[0066] Step 13: Create a mounting cavity on the circuit board from the side facing the first board surface to expose the solder mask layer.

[0067] In this embodiment, the fabrication method is used to fabricate a circuit board. By creating mounting cavities on the circuit board, a solder resist layer applied to the first surface of the core board can be exposed. Thus, the solder pads exposed through the solder resist layer allow electronic devices to be mounted within the mounting cavity.

[0068] In step 11, the two sides of the copper foil laminated on the insulating substrate are the two sides of the insulating substrate along the thickness direction of the insulating substrate.

[0069] Here, at least one layer of copper foil can be hot-pressed outwards layer by layer on both sides of the insulating substrate to form a core board.

[0070] In this embodiment of the disclosure, during the hot-pressing of multilayer copper foil, each layer of copper foil needs to be separated by an insulating layer. This insulating layer may include fiberglass cloth and a prepreg made of resin; this embodiment of the disclosure does not limit this to any particular type.

[0071] Here, the copper foil on both sides of the insulating substrate can have a symmetrical structure.

[0072] In this embodiment of the disclosure, circuit diagrams can be etched onto copper foil using different etching methods to form a core board. These etching methods include chemical etching, mechanical engraving, or laser etching, and this embodiment of the disclosure does not limit the specific methods used.

[0073] In step 12, the first and second surfaces of the core board are two oppositely arranged surfaces in the thickness direction of the core board.

[0074] In this embodiment of the present disclosure, a solder resist layer is applied to the first board surface. Here, the solder resist layer is used to protect the circuit diagram on the first board surface.

[0075] It should be noted that the solder resist layer can be applied to the first board surface through processes such as screen printing, inkjet printing, or electrostatic spraying.

[0076] In this embodiment of the disclosure, step 11 can form a multilayer core board. That is, the circuit board can be composed of multiple layers of core boards stacked together. Here, the core board to which the solder resist layer is applied can be any one of the multiple layers of core boards.

[0077] For example, such as Figure 2 As shown, L1 to L12 indicate that the circuit board has a total of 12 layers. PP indicates the prepreg. The circuit board has core board 1, core board 2, core board 3, and core board 4. Core board 1 consists of an insulating substrate core and copper foils L3 and L4 on both sides; core board 2 consists of an insulating substrate core and copper foils L5 and L6 on both sides; core board 3 consists of an insulating substrate core and copper foils L7 and L8 on both sides; core board 4 consists of an insulating substrate core and copper foils L9 and L10 on both sides.

[0078] Here, a solder mask layer can be set on L7 of the core board 3. After the mounting cavity 1 is opened on the circuit board, the solder mask layer can be exposed to the outside through the opening of the mounting cavity 1.

[0079] Of course, a solder mask layer can also be set on L9 of the core board 4. After the mounting cavity 2 is opened on the circuit board, the solder mask layer can be exposed to the outside through the opening of the mounting cavity 2.

[0080] It should be noted that, depending on the different depths of the mounting cavity opened, the embodiments of this disclosure may also select to provide a solder resist layer on the core board 2, and the embodiments of this disclosure do not limit this.

[0081] In this embodiment of the disclosure, after applying a solder resist layer, a sheet structure can be laminated onto at least the second surface of the core board to form a circuit board. The sheet structure may include at least one insulating sheet structure and at least one copper foil sheet structure.

[0082] For example, such as Figure 2 and Figure 3As shown, after a solder resist layer A is applied to L9 of core board 4, a sheet structure can be laminated onto L10 of core board 4 to form the 11th layer L11 of the circuit board, and a sheet structure can be laminated onto L3 of core board 1 of the circuit board to form the 2nd layer L2 of the circuit board. After forming layers 2 to 11 L11, sheet structures can be laminated onto layers 2 and 11 L11 of the circuit board to form layers 1 to 12 L12. In this way, a circuit board with 12 layers can be formed.

[0083] In step 13, a mounting cavity is formed on the circuit board from the side facing the first board surface. Here, the side of the circuit board facing the first board surface can be understood as the top layer of the circuit board, i.e., the side where the first layer of the circuit board is located, and the side of the circuit board facing the second board surface can be understood as the bottom layer of the circuit board.

[0084] In this embodiment of the disclosure, after the circuit board is formed, the depth of the mounting cavity is also different depending on the number of layers of the core board to which the solder resist layer is applied.

[0085] For example, such as Figure 2 As shown, the solder resist layer is set on the seventh layer L7 of the circuit board (that is, the solder resist layer is set on the first surface of the core board 3), and the corresponding mounting cavity 1 has a first depth.

[0086] The solder resist layer is set on the ninth layer L9 of the circuit board (i.e., the solder resist layer is set on the first surface of the core board 4), and the corresponding mounting cavity 2 has a second depth; the first depth is less than the second depth.

[0087] In this embodiment, a mounting cavity can be formed along the thickness direction of the circuit board. Forming the mounting cavity exposes the solder resist layer.

[0088] Here, as Figure 3 As shown, solder resist layer A can be exposed through the opening of the mounting cavity, and this solder resist layer A can be located at the bottom of the mounting cavity. In this way, electronic components can be inserted into the mounting cavity through the opening of the mounting cavity and soldered onto the exposed pads of the solder resist layer, thus realizing the mounting of electronic components in the mounting cavity of the circuit board.

[0089] It should be noted that the resulting circuit board with mounting cavity can be of different types.

[0090] In some embodiments, forming a circuit board with a mounting cavity may include a radio frequency (RF) circuit board, which can be used to receive and transmit communication signals of an electronic device.

[0091] In other embodiments, forming a circuit board with a mounting cavity may include a power circuit board for implementing power-related functions.

[0092] For example, existing circuit boards cannot mount electronic devices within the mounting cavity, thus limiting the mounting of electronic devices.

[0093] Based on this, embodiments of this disclosure propose applying a solder resist layer to the first surface of the core board, and forming a circuit board by laminating a sheet structure onto at least the second surface of the core board. A mounting cavity is formed on the circuit board from the side facing the first surface to expose the solder resist layer. In other words, embodiments of this disclosure pre-apply a solder resist layer during the circuit board formation process and expose the solder resist layer through the mounting cavity, enabling the mounting of electronic devices within the mounting cavity.

[0094] This not only makes the installation of electronic components on the circuit board more flexible, but also allows for the placement of more electronic components on the circuit board by installing them in the mounting cavity, thereby reducing the space occupied by the circuit board.

[0095] In some embodiments, the preparation method further includes:

[0096] Browning is applied to the solder resist layer;

[0097] The protective layer is then bonded to the browned solder resist layer.

[0098] After opening the mounting cavity, peel off the protective layer from the solder resist layer.

[0099] In this embodiment of the disclosure, browning the solder resist layer may include forming a rough surface on the surface of the solder resist layer.

[0100] Here, the rough surface can be composed of an oxide layer (e.g., Cu2O).

[0101] In this embodiment of the disclosure, attaching the protective layer to the browned solder resist layer may include: attaching the protective layer to the rough surface of the browned solder resist layer.

[0102] It should be noted that a rough surface can improve the adhesion between the solder resist layer and the protective layer, reducing the likelihood of delamination after lamination.

[0103] In this embodiment of the disclosure, a protective layer is used to protect the solder resist layer and reduce the impact of damage to the solder resist layer on welding.

[0104] Here, the protective layer adheres to the rough surface of the solder resist layer. For example, as... Figure 3 As shown, protective layer B is bonded to the browned solder resist layer A.

[0105] In this embodiment of the disclosure, the protective layer may be formed of different materials.

[0106] In some embodiments, the protective layer may include a peelable adhesive. This peelable adhesive is used to protect the solder mask from damage during the process of cutting the circuit board to form mounting cavities.

[0107] For liquid peelable adhesives, a protective layer can be formed on the solder resist layer after curing via screen printing or spraying. For dry film peelable adhesives, curing can be performed by hot pressing or ultraviolet (UV) light after the solder resist layer is applied.

[0108] In this embodiment of the disclosure, during the process of pressing the peelable adhesive onto the browned solder resist layer, the pressing time and pressing temperature of the peelable adhesive can be set according to the material of the peelable adhesive. For example, the pressing time can be set between 170 degrees and 180 degrees; the pressing temperature can be set between 2 hours and 3 hours.

[0109] In other embodiments, the protective layer may further include a polyimide film, i.e., a PI film. This PI film can be used to protect the solder resist layer during high-temperature processes (such as lamination or curing), and can also be used to protect the solder resist layer and reduce damage or contamination during processes such as drilling and milling.

[0110] In this embodiment of the disclosure, after the mounting cavity is opened, the protective layer is peeled off to expose the solder resist layer in order to facilitate welding.

[0111] It should be noted that if the protective layer includes a peelable adhesive, the peelable adhesive can be peeled off from the solder resist layer using tweezers or a tearing device.

[0112] When the protective layer includes a PI film, if the PI film is an adhesive-coated PI film, it can be peeled off by heating or chemical assistance. If the PI film is an adhesive-free PI film, it can be removed mechanically.

[0113] Understandably, browning the solder resist layer allows for better adhesion between the protective layer and the solder resist. By setting a protective layer and then peeling it off after creating the mounting cavity, not only can the solder resist layer be better protected during the creation of the mounting cavity, but peeling off the protective layer also allows for better installation of electronic components within the mounting cavity of the circuit board.

[0114] In some embodiments, the protective layer includes a peelable adhesive;

[0115] The preparation method also includes:

[0116] Install the guide plate between the peelable adhesive layer and the solder resist layer;

[0117] A mounting cavity is formed on the circuit board from the side facing the first panel, including:

[0118] From the side facing the first board, cut along the thickness direction of the board to the guide plate, and remove the cut portion from the board to form a mounting cavity.

[0119] In this embodiment, a guide plate is installed between the silicone sealant and the solder resist layer. Cutting is stopped when the circuit board is cut along its thickness direction to the guide plate, thus controlling the depth of the cutting mounting cavity and improving cutting accuracy. Furthermore, the guide plate also reduces vibration or deformation of the circuit board during cutting.

[0120] It should be noted that the guide plate includes a mechanical contact guide plate, which can trigger a stop to cutting by a change in resistance. For example, the hardness of the mechanical contact guide plate is greater than that of the circuit board substrate, so a change in resistance will be felt when cutting to the mechanical contact guide plate.

[0121] Of course, the guide plate also includes an optical guide plate, where a reflected signal detected by a photoelectric sensor can trigger a stop to the cutting process. For example, a highly reflective material can be printed on the optical guide plate so that the photoelectric sensor can detect the reflected signal.

[0122] In this embodiment of the disclosure, the circuit board may have a first edge, a second edge, a third edge and a fourth edge. The first edge and the third edge may be two opposite edges of the circuit board along the length direction, and the second edge and the fourth edge may be two opposite edges of the circuit board along the width direction.

[0123] Here, during the cutting process along the thickness direction of the circuit board, the cutting can be carried out sequentially from the first edge, the second edge, the third edge and the fourth edge to the guide plate.

[0124] Here, the cutting method may include laser cutting or die stamping cutting, etc. Among them, laser cutting may include UV laser cutting or fiber laser cutting, etc., and the embodiments disclosed herein are not limited thereto.

[0125] In this embodiment of the disclosure, after cutting is completed, the cut portion can be removed from the circuit board by opening the cover to form a mounting cavity.

[0126] For example, such as Figure 3 As shown, after local depth control and laser cutting, the cut portion can be removed from the circuit board by opening the cover to form an mounting cavity.

[0127] It should be noted that the opening method can be mechanical, laser, or chemical etching, etc., and the embodiments disclosed herein are not limited to these methods.

[0128] In this embodiment of the disclosure, after the mounting cavity is opened, the peelable adhesive attached to the solder resist layer is peeled off to expose the solder resist layer.

[0129] It should be noted that, since the guide plate is positioned between the peelable adhesive and the solder resist layer, and is bonded by the peelable adhesive, it is removed from the solder resist layer along with the adhesive during the peeling process. This improves cutting accuracy while also ensuring the guide plate is not obscured by the solder resist layer, allowing for better exposure of the solder resist and improving the performance of soldering electronic components within the mounting cavity.

[0130] In some embodiments, the protective layer includes a polyimide film;

[0131] The preparation method also includes:

[0132] After peeling off the polyimide film, solder mask is applied inside the mounting cavity of the circuit board.

[0133] In this embodiment of the disclosure, since the process of peeling off the polyimide film may remove part of the solder resist layer, or the process of cutting the circuit board to form the mounting cavity may damage the solder resist layer, this embodiment of the disclosure proposes to perform solder resist application within the mounting cavity of the circuit board after peeling off the polyimide film.

[0134] Here, performing solder resist within the mounting cavity of the circuit board may include performing solder resist treatment on the exposed solder resist layer.

[0135] It is understood that the embodiments of this disclosure can compensate for the damaged solder resist layer by performing solder resist on the mounting cavity after peeling off the polyimide film, thereby improving the performance of soldering electronic devices in the mounting cavity.

[0136] In this embodiment of the disclosure, anti-welding can be performed on the mounting cavity through different processes.

[0137] In some embodiments, performing solder resist within the mounting cavity of the circuit board includes:

[0138] Ink is sprayed into the mounting cavity using an electrostatic spraying process.

[0139] In this embodiment of the disclosure, spraying ink into the mounting cavity using an electrostatic spraying process may include: using the principle of electrostatic adsorption, driving the spray gun in a reciprocating manner to apply high voltage electrostatic force to the solder resist ink particles so that they are sprayed onto the solder resist layer in the mounting cavity.

[0140] For example, such as Figure 4 As shown, the black line represents the electric field 41, and the dots represent solder resist ink particles 42. The spray gun 43 on the left uses high-speed rotation to spray the solder resist ink particles 42 along the horizontal electric field lines toward the circuit board 44.

[0141] It is understandable that applying ink to the mounting cavity through electrostatic spraying can make the solder resist more uniform and improve the performance of the electronic components soldered inside the mounting cavity.

[0142] In some embodiments, the preparation method further includes:

[0143] Before applying solder resist to the inside of the mounting cavity, apply solder resist to the outside of the mounting cavity of the circuit board.

[0144] In this embodiment of the disclosure, after peeling off the polyimide film, solder resist can be performed first outside the mounting cavity of the circuit board, and then solder resist can be performed inside the mounting cavity of the circuit board.

[0145] It should be noted that the process for applying solder resist inside the mounting cavity can differ from the process for applying it outside the mounting cavity. Here, solder resist can first be applied to the outside of the mounting cavity using a printing ink process, and then the ink can be sprayed into the mounting cavity using an electrostatic spraying process.

[0146] It is understood that the embodiments of this disclosure perform solder resist not only inside the mounting cavity of the circuit board but also outside the mounting cavity. This can minimize the impact of circuit board cutting on the soldering of electronic components, thereby achieving better soldering of electronic components both inside and outside the mounting cavity. Furthermore, performing solder resist outside the mounting cavity first, and then inside the mounting cavity, can reduce contamination of the mounting cavity during the solder resist process outside the mounting cavity, and improve the effectiveness of solder resist inside the mounting cavity.

[0147] In some embodiments, the preparation method further includes:

[0148] Cut the solder resist layer outside the specified location and peel off the protective layer outside the specified location.

[0149] In this embodiment of the disclosure, the designated location can be set according to actual needs.

[0150] For example, the designated location may include the center of the first board surface or the location surrounded by through holes or buried holes on the circuit board, etc., and the embodiments disclosed herein do not limit this.

[0151] It should be noted that peeling off the protective layer outside the designated location may include peeling off the peelable adhesive or polyimide film outside the designated location.

[0152] In this embodiment of the disclosure, the solder resist layer outside the designated location is cut while the solder resist layer at the designated location is retained. This enables selective cutting and improves the reliability of circuit board manufacturing.

[0153] Furthermore, by peeling off the protective layer outside the designated location and retaining the protective layer at the designated location, not only can the solder resist layer at the designated location be protected, but the electrical influence of the protective layer on the non-designated location can also be reduced during the lamination of the circuit board, thereby improving the reliability of the circuit board manufacturing.

[0154] In some embodiments, the thickness of the prepreg layer between the bottom copper foil and the bottom of the mounting cavity in the circuit board is less than or equal to 150 micrometers;

[0155] And / or,

[0156] The depth of the mounting cavity is between 1 mm and 1.8 mm;

[0157] And / or,

[0158] The minimum distance between the exposed solder pads of the solder resist layer in the mounting cavity and the cavity wall is greater than or equal to 0.5 mm.

[0159] It is understood that, on the one hand, the thickness of the semi-cured film between the bottom copper foil in the circuit board and the bottom of the mounting cavity is set to less than or equal to 150 micrometers in the embodiments of this disclosure. This not only improves the insulation reliability of the circuit board, but also reduces the impact of excessive thickness on lamination or signal integrity.

[0160] On the other hand, the embodiments of this disclosure enable the fabrication of mounting cavities with a depth exceeding 1 mm on a circuit board. Furthermore, by setting the depth of the mounting cavity between 1 mm and 1.8 mm, the depth of the mounting cavity can support the electronic devices disposed on both sides of the mounting cavity along the thickness direction of the circuit board during the stacking of circuit boards with mounting cavities, thereby enabling the installation of more electronic devices on the circuit board in the thickness direction.

[0161] Furthermore, the embodiments disclosed herein can achieve a minimum distance of 0.5 mm between the pads inside the mounting cavity and the cavity wall, which allows for the placement of more pads within the mounting cavity, thereby enabling the soldering of more electronic devices within the mounting cavity.

[0162] For example, such as Figure 5 and Figure 6 As shown, in this embodiment of the present disclosure, the depth h of the mounting cavity of the circuit board can be set to 1.8 mm, and the minimum distance s between the pad at the bottom of the mounting cavity and the cavity wall can be set to 0.5 mm. Furthermore, pads 51 can be provided both inside and outside the mounting cavity of the circuit board for mounting electronic components, enabling the soldering of more electronic components in the thickness direction of the circuit board.

[0163] In some embodiments, the depth of the mounting cavity is positively correlated with the thickness of the circuit board.

[0164] In this embodiment of the disclosure, the thicker the circuit board, the deeper the corresponding mounting cavity can be set.

[0165] For example, the thickness of the circuit board can be set between 2.1 mm and 2.3 mm, and the corresponding depth of the mounting cavity can be set to 1.8 mm.

[0166] For example, the thickness of the circuit board can be set between 1.9 mm and 2.1 mm, and the corresponding depth of the mounting cavity can be set to 1.6 mm.

[0167] It is understandable that by understanding the relationship between the depth of the mounting cavity and the thickness of the circuit board, a more reliable circuit board can be produced during the fabrication of a circuit board with a mounting cavity.

[0168] To better understand the preparation method proposed in one or more of the above embodiments, examples of embodiments of this disclosure are as follows:

[0169] Figure 7 This is a schematic diagram illustrating a method for fabricating a circuit board by bonding a peelable adhesive according to an exemplary embodiment. Figure 7 As shown, the method for manufacturing the circuit board includes the following steps:

[0170] 701. Material cutting: The copper foil on both sides of the insulating substrate can be cut into production panels according to the design dimensions.

[0171] 702. Internal drilling; allows drilling into insulating substrates and copper foil. Through-holes or blind slots can be used to achieve interconnection or heat dissipation between different layers of the circuit board.

[0172] 703. Circuit; Here, a circuit diagram is formed on copper foil by image transfer or etching. For example, as... Figure 2 and Figure 3 It can form the 3rd to 10th layers of a circuit board.

[0173] 704. Solder resist; Here, a solder resist layer can be applied to the 9th layer of the circuit board. This solder resist layer covers the non-soldered areas, enabling short circuit prevention and providing insulation protection.

[0174] 705. Browning; Here, the solder resist layer is browned to make its surface rough.

[0175] 706. Apply peelable adhesive; here, the peelable adhesive is applied to the rough surface of the solder mask. It should be noted that a guide plate can also be placed between the peelable adhesive and the solder mask. This guide plate is used to trigger a stop to the cutting process during the process of cutting the circuit board to form the mounting cavity.

[0176] 707. Lamination; Here, the peelable adhesive is laminated onto the browned solder resist layer. It should be noted that lamination can be performed in a cleanroom environment to reduce contamination.

[0177] 708. Laser cutting and peeling of the adhesive; here, laser cutting of the solder mask outside the designated location, and removal of the peelable adhesive outside the designated location.

[0178] 709. Pressing; Here, it can refer to the pressing between the prepreg and the core board. That is, pressing the prepreg with the third layer of copper foil, and pressing the prepreg with the tenth layer of copper foil.

[0179] 710. Laser; here, laser drilling can be used to obtain high-precision blind holes or through holes.

[0180] 711. Drilling; here, mechanical drilling may be used. It should be noted that the hole can be obtained using steps 710 and / or 711.

[0181] 712. Electroplating; Here, blind or through holes are metallized by chemical copper plating.

[0182] 713. Resin plugging: Here, blind holes or through holes are filled with resin to ensure a smooth surface.

[0183] 714. Route; here, such as Figure 2 and Figure 3 It can form the 2nd to 11th layers of a circuit board.

[0184] 715. Second pressing; here, it can be that the semi-cured material is pressed together with the second and eleventh layers respectively.

[0185] 716. Laser engraving; 717. Drilling; 718. Electroplating;

[0186] 719. Route; such as Figure 2 and Figure 3 It can form the first to twelfth layers of a circuit board.

[0187] 720. Anti-welding; 721. Chemical alloying; 722. Outlining;

[0188] 723. Depth Control; Here, depth control includes locally deepening the circuit board through laser cutting. It should be noted that, in the embodiments of this disclosure, the depth of the cutting mounting cavity can be controlled by a guide plate during the cutting process, thereby improving cutting accuracy.

[0189] 724. Open the cover; Here, after cutting the circuit board, the cut portion can be removed from the circuit board to form a mounting cavity. It should be noted that after opening the cover, the peelable adhesive can be peeled off from the solder mask layer.

[0190] 725. Scooping from the inner tank; 726. Flying needle; 727. Visual inspection; 728. Packaging; 729. Warehousing.

[0191] It is understood that in steps 704 to 706, the embodiments of this disclosure not only enable the solder resist layer to be exposed after the mounting cavity is opened by pre-setting the solder resist layer, thus allowing electronic devices to be soldered within the mounting cavity, but also enable the solder resist layer to be protected during circuit board cutting by providing peelable adhesive, and to be better exposed by peeling the peelable adhesive off the solder resist layer after opening the cover. In steps 723 and 724, the depth of cutting the mounting cavity can be controlled by providing a guide plate, and the mounting cavity is formed on the circuit board by opening the cover.

[0192] Figure 8 This is a schematic diagram illustrating a method for fabricating a circuit board by laminating a PI film according to an exemplary embodiment. Figure 8 As shown, the method for manufacturing the circuit board includes the following steps:

[0193] 801. Cutting and preparing boards;

[0194] 802. Internal drilling;

[0195] 803, Route 1; Here, it may include etching lines to form a circuit diagram.

[0196] 804, AOI-; Here, defects in the circuit diagram are automatically detected by Automated Optical Inspection (AOI).

[0197] 805. Solder resist layer; Here, the solder resist layer is the solder resist layer that is exposed when the mounting cavity is opened on the circuit board.

[0198] 806. Browning I; Here, the solder resist layer from step 805 is browned to make the surface of the solder resist layer rough.

[0199] 807. Apply PI film; Here, the PI film is applied to the rough surface of the solder resist layer.

[0200] 808. Pressing and bonding; Here, it means pressing the PI film onto the browned solder resist layer.

[0201] 809. Copper Reduction; 810. Embedded Drilling; 811. Electroplating; 812. Embedded Hole Plug; 813. Circuit II; 814. AOI II; 815. Browning II; 816. Lamination II;

[0202] 817. DLD III; Here, the designed graphic is precisely transferred through Direct Laser Imaging for Layer (DLD).

[0203] 818. Electroplating to fill holes; 819. Circuit 3; 820. AOI 3; 821. Outer layer lamination; 822. Outer layer DLD; 823. Outer layer electroplating to fill holes; 824. Outer layer; 825. Through-hole drilling;

[0204] 826. Controlled depth milling; Here, in this embodiment of the disclosure, the PI film adhered to the solder resist layer can be peeled off.

[0205] 827. Outer DLD cap opening; Here, the cap opening forms a mounting cavity, and the buried vias and pads inside the mounting cavity can be exposed through the opening of the mounting cavity.

[0206] 828. Outer AOI;

[0207] 829. Solder resist; Here, in this embodiment of the disclosure, solder resist can be performed on the outside of the mounting cavity of the circuit board.

[0208] 830. Secondary solder resist; Here, in this embodiment of the disclosure, solder resist can be performed inside the mounting cavity of the circuit board to achieve better soldering of electronic devices inside the mounting cavity.

[0209] 831. Laser marking; 832. Metallization; 833. Molding; 834. Testing;

[0210] 835. OSP; Organic Solderability Preservative (OSP) is used to prevent copper oxidation and maintain the solderability of pads.

[0211] 836. Final inspection; 837. Packaging.

[0212] It is understood that in steps 805 to 807, the embodiments of this disclosure not only enable the solder resist layer to be exposed after the mounting cavity is opened by pre-setting the solder resist layer, thus allowing electronic devices to be soldered inside the mounting cavity, but also protect the solder resist layer by setting the PI film. In steps 829 and 830, by performing solder resist twice—first applying solder resist to the outside of the mounting cavity of the circuit board, and then applying solder resist to the inside of the mounting cavity—the loss of the solder resist layer caused by cutting the circuit board or peeling off the PI film can be compensated. This not only improves the soldering performance of electronic devices soldered inside the mounting cavity, but also improves the soldering performance of electronic devices soldered outside the mounting cavity.

[0213] This disclosure also provides a circuit board. The circuit board is manufactured using one or more of the methods described in the above embodiments. Here, Figure 3 and Figure 5 The circuit board with mounting cavity shown can be manufactured using one or more of the methods described above.

[0214] It is understood that the circuit boards manufactured by the methods of one or more of the above embodiments in this disclosure can realize the mounting of electronic devices within the mounting cavity of the circuit board. This not only makes the mounting of electronic devices on the circuit board more flexible, but also allows for the arrangement of more electronic devices in the thickness direction of the circuit board by mounting them within the mounting cavity, thereby reducing the space occupied by the circuit board.

[0215] This disclosure also provides a circuit board assembly. The circuit board assembly includes: a plurality of circuit boards stacked together;

[0216] The circuit board having a mounting cavity among multiple circuit boards is manufactured using the preparation method of one or more embodiments described above.

[0217] It is understood that the circuit board with mounting cavity manufactured by one or more of the above-described embodiments of the present disclosure can realize the mounting of electronic devices within the mounting cavity. This not only makes the mounting of electronic devices on the circuit board more flexible, but also allows for the arrangement of more electronic devices in the thickness direction of the circuit board by mounting them within the mounting cavity, thereby reducing the space occupied by the circuit board.

[0218] In some embodiments, electronic devices are mounted on both sides of the mounting cavity of at least one circuit board in the circuit board assembly along the thickness direction of the circuit board.

[0219] In this embodiment of the disclosure, the circuit board assembly may include at least one circuit board having a mounting cavity. The circuit board assembly may consist of a single circuit board with electronic devices mounted on both sides of its mounting cavity along the thickness direction of the circuit board, or it may consist of multiple circuit boards with electronic devices mounted on both sides of their mounting cavities. This embodiment of the disclosure does not impose any limitations on this.

[0220] It is understandable that by mounting electronic components on both sides of the circuit board along its thickness direction within the mounting cavity, the number of electronic components that can be arranged in the thickness direction of the circuit board assembly can be increased, allowing for the arrangement of more electronic components in the circuit board assembly. This not only reduces the space occupied by the circuit board assembly in the mobile terminal and improves the space utilization of the circuit board assembly, but also allows for more flexible placement of electronic components.

[0221] Furthermore, by mounting electronic devices on both sides of the circuit board along its thickness direction within the mounting cavities of multiple circuit boards, the electronic devices can be stacked to the maximum extent in the thickness direction of the circuit board, further enabling the circuit board assembly to have more electronic devices arranged in the thickness direction.

[0222] For example, the Z direction can be the thickness direction of the circuit board, the X direction can be the length direction of the circuit board, and the Y direction can be the width direction of the circuit board. In the circuit board assembly of this disclosure, electronic devices can be mounted on both sides of the mounting cavity along the Z direction, allowing for the arrangement of more electronic devices in the Z direction. Furthermore, since more electronic devices can be arranged in the Z direction, the size of the circuit board assembly in the X and / or Y directions can be reduced, thereby reducing the space occupied by the circuit board assembly in the mobile terminal.

[0223] In some embodiments, such as Figure 9A and Figure 9B As shown, the multiple circuit boards include a first circuit board 100, a second circuit board 200 and a third circuit board 300 stacked in sequence;

[0224] The second circuit board 200 covers the opening of the mounting cavity of the first circuit board 100;

[0225] The third circuit board 300 covers the opening of the mounting cavity of the second circuit board 200;

[0226] Electronic devices are mounted on both sides of the mounting cavity along the thickness direction inside the first circuit board 100.

[0227] And / or,

[0228] Electronic devices are mounted on both sides of the mounting cavity along the thickness direction inside the second circuit board 200.

[0229] In this embodiment of the disclosure, such as Figure 9A and Figure 9B As shown, both the mounting cavity of the first circuit board 100 and the mounting cavity of the second circuit board 200 have solder pads 301, which can be used for soldering resistors, capacitors, inductors 305 and various IC devices 302. Of course, shielding structures 303 can also be provided in the mounting cavities of the first circuit board 100 and the second circuit board 200, and connectors 304 can be provided on each circuit board.

[0230] For example, such as Figure 9A As shown, by mounting electronic devices on both sides along the thickness direction within the mounting cavity of the first circuit board 100, more electronic devices can be arranged in the circuit board assembly in the thickness direction.

[0231] For example, such as Figure 9B As shown, by mounting electronic devices on both sides along the thickness direction within the mounting cavity of the second circuit board 200, more electronic devices can be arranged in the circuit board assembly in the thickness direction.

[0232] It is understood that the embodiments of this disclosure enable two electronic devices with accommodating cavities to be stacked, and the electronic devices are installed in the mounting cavity of the first circuit board and / or the mounting cavity of the second circuit board. This not only makes the layout of electronic devices in the circuit board assembly more flexible, but also enables the circuit board assembly to lay out more electronic devices in the thickness direction.

[0233] This disclosure also proposes a mobile terminal. The mobile terminal includes:

[0234] case;

[0235] The circuit board assembly as described in one or more of the above embodiments is disposed in the housing.

[0236] In this embodiment of the disclosure, the mobile terminal may include a smartphone, laptop, tablet computer, or smart wearable device (such as a smartwatch or smart bracelet), etc., and this embodiment of the disclosure does not limit it.

[0237] The housing of the aforementioned mobile terminal may include a mid-frame and a border, the mid-frame being located within the area enclosed by the border, and the circuit board assembly being disposed on the mid-frame and located within the area enclosed by the border.

[0238] It is understood that the mobile terminal includes a circuit board assembly, which comprises a circuit board with a mounting cavity manufactured by one or more of the methods described above, enabling the mounting of electronic devices within the mounting cavity. This not only makes the mounting of electronic devices on the circuit board more flexible, but also allows for the arrangement of more electronic devices in the thickness direction of the circuit board by mounting them within the mounting cavity, thereby reducing the space occupied by the circuit board.

[0239] Figure 10 This is a structural block diagram of a mobile terminal according to an exemplary embodiment. For example, the mobile terminal 1000 may be a mobile phone, computer, digital broadcasting terminal, messaging device, game console, tablet device, medical device, fitness device, personal digital assistant, etc.

[0240] Reference Figure 10 The mobile terminal 1000 may include one or more of the following components: processing component 1002, memory 1004, power supply component 1006, multimedia component 1008, audio component 1010, input / output (I / O) interface 1012, sensor component 1014, and communication component 1016.

[0241] Processing component 1002 typically controls the overall operation of mobile terminal 1000, such as operations associated with at least one of display, telephone call, data communication, camera operation, and recording operation. Processing component 1002 may include one or more processors 1020 to execute instructions to perform all or part of the steps of the methods described above. Furthermore, processing component 1002 may include one or more modules to facilitate interaction between processing component 1002 and other components. For example, processing component 1002 may include a multimedia module to facilitate interaction between multimedia component 1008 and processing component 1002.

[0242] Memory 1004 is configured to store various types of data to support operation on mobile terminal 1000. Examples of such data include at least one of the following: instructions for any application or method operating on mobile terminal 1000, contact data, phonebook data, messages, pictures, and videos. Memory 1004 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0243] The power supply component 1006 provides power to various components of the mobile terminal 1000. The power supply component 1006 may include at least one of the following: a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power to the mobile terminal 1000.

[0244] Multimedia component 1008 includes a screen that provides an output interface between mobile terminal 1000 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touchscreen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensors may sense not only the boundaries of touch or swipe actions but also the duration and pressure associated with the touch or swipe operation. In some embodiments, multimedia component 1008 includes a front-facing camera and / or a rear-facing camera. When mobile terminal 1000 is in an operating mode, such as a shooting mode or video mode, the front-facing camera and / or rear-facing camera may receive external multimedia data. Each front-facing camera and rear-facing camera may be a fixed optical lens system or have focal length and optical zoom capabilities.

[0245] Audio component 1010 is configured to output and / or input audio signals. For example, audio component 1010 includes a microphone (MIC) configured to receive external audio signals when mobile terminal 1000 is in an operating mode, such as call mode, recording mode, and voice recognition mode. The received audio signals may be further stored in memory 1004 or transmitted via communication component 1016. In some embodiments, audio component 1010 also includes a speaker for outputting audio signals.

[0246] I / O interface 1012 provides an interface between processing component 1002 and peripheral interface modules, such as keyboards, click wheels, and buttons. These buttons may include, but are not limited to, home buttons, volume buttons, power buttons, and lock buttons.

[0247] Sensor assembly 1014 includes one or more sensors for providing state assessments of various aspects of mobile terminal 1000. For example, sensor assembly 1014 may detect the on / off state of mobile terminal 1000, the relative positioning of components such as the display and keypad of mobile terminal 1000, changes in position of mobile terminal 1000 or one of its components, the presence or absence of user contact with mobile terminal 1000, orientation or acceleration / deceleration of mobile terminal 1000, and temperature changes of mobile terminal 1000. Sensor assembly 1014 may include a proximity sensor configured to detect the presence of nearby objects without any physical contact. Sensor assembly 1014 may also include an optical sensor, such as a complementary metal-oxide-semiconductor (CMOS) or charge-coupled device (CCD) image sensor, for use in imaging applications. In some embodiments, sensor assembly 1014 may also include, but is not limited to, at least one of the following: an accelerometer, a gyroscope, a magnetometer, a pressure sensor, and a temperature sensor.

[0248] Communication component 1016 is configured to facilitate wired or wireless communication between mobile terminal 1000 and other devices. Mobile terminal 1000 can access wireless networks based on communication standards, such as Wi-Fi, 4G, 5G, or combinations thereof. In one exemplary embodiment, communication component 1016 receives broadcast signals or broadcast-related information from an external broadcast management system via a broadcast channel. In one exemplary embodiment, communication component 1016 also includes a Near Field Communication (NFC) module to facilitate short-range communication. For example, the NFC module may be implemented based on Radio Frequency Identification (RFID), Infrared Data Association (IrDA), Ultra Wide Band (UWB), Bluetooth (BT), and other technologies.

[0249] In an exemplary embodiment, the mobile terminal 1000 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components.

[0250] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0251] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A method for manufacturing a circuit board, characterized in that, The preparation method includes: Copper foil is laminated onto both sides of an insulating substrate, and a circuit pattern is etched onto the copper foil to form a core board. A solder resist layer is applied to the first surface of the core board, and a sheet structure is pressed onto at least the second surface of the core board to form the circuit board; A mounting cavity is formed on the circuit board from the side facing the first panel to expose the solder resist layer.

2. The preparation method according to claim 1, characterized in that, The preparation method further includes: The solder resist layer is browned. The protective layer is attached to the browned solder resist layer; After the mounting cavity is opened, the protective layer is peeled off from the solder resist layer.

3. The preparation method according to claim 2, characterized in that, The protective layer includes a peelable adhesive; The preparation method further includes: Install the guide plate between the peelable adhesive and the solder resist layer; The method of creating a mounting cavity on the circuit board from the side facing the first plate includes: From the side facing the first plate, a cut is made along the thickness direction of the circuit board to the guide plate, and the cut portion is removed from the circuit board to form the mounting cavity.

4. The preparation method according to claim 2, characterized in that, The protective layer includes a polyimide film; The preparation method further includes: After the polyimide film is peeled off, solder resist is applied within the mounting cavity of the circuit board.

5. The preparation method according to claim 4, characterized in that, The preparation method further includes: Before performing solder resist on the inside of the mounting cavity, solder resist is performed on the outside of the mounting cavity of the circuit board.

6. The preparation method according to claim 4, characterized in that, Performing solder resist within the mounting cavity of the circuit board includes: Ink is sprayed into the mounting cavity using an electrostatic spraying process.

7. The preparation method according to claim 2, characterized in that, The preparation method further includes: Cut the solder resist layer outside the designated location and peel off the protective layer outside the designated location.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The thickness of the prepreg layer between the bottom copper foil of the circuit board and the bottom of the mounting cavity is less than or equal to 150 micrometers. And / or, The depth of the mounting cavity is between 1 mm and 1.8 mm; And / or, The minimum distance between the exposed solder pads of the solder resist layer and the cavity wall of the mounting cavity is greater than or equal to 0.5 mm.

9. The preparation method according to any one of claims 1 to 7, characterized in that, The depth of the mounting cavity is positively correlated with the thickness of the circuit board.

10. A circuit board, characterized in that, The circuit board is manufactured using the preparation method described in any one of claims 1 to 9.

11. A circuit board assembly, characterized in that, include: Multiple circuit boards stacked together; The circuit boards having mounting cavities among the plurality of said circuit boards are manufactured using the preparation method according to any one of claims 1 to 9.

12. The circuit board assembly according to claim 11, characterized in that, In the circuit board assembly, at least one of the circuit boards has electronic devices mounted on both sides of the mounting cavity along the thickness direction of the circuit board.

13. The circuit board assembly according to claim 12, characterized in that, The plurality of circuit boards include a first circuit board, a second circuit board, and a third circuit board stacked sequentially; The second circuit board covers the opening of the mounting cavity of the first circuit board; The third circuit board covers the opening of the mounting cavity of the second circuit board; The electronic devices are mounted on both sides of the mounting cavity of the first circuit board along the thickness direction. And / or, The electronic devices are mounted on both sides of the mounting cavity of the second circuit board along the thickness direction.

14. A mobile terminal, characterized in that, include: case; The circuit board assembly as described in any one of claims 11 to 13 is disposed in the housing.

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