A circuit board and a method for manufacturing a non-glue-overflowing circuit board stepped groove

Abstract

The application discloses a circuit board and a manufacturing method of a glue-overflow-free circuit board stepped groove. The manufacturing method comprises the following steps: providing a plurality of core boards and a plurality of prepregs; slotting at least part of the first preset positions of the core boards and at least part of the second preset positions of the prepregs to form first through holes in the core boards and second through holes in the prepregs; arranging glue-blocking films covering at least the sidewalls of the second through holes in the prepregs; stacking the core boards and the prepregs in a predetermined order; arranging a sub-board on the side of the outermost prepreg away from the core board; pressing the core boards, the prepregs and the sub-board to form a mother board; and controlling the depth of the groove of the mother board to obtain the circuit board stepped groove. The above technical scheme realizes the manufacturing of the glue-overflow-free circuit board stepped groove and reduces the manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing, and more particularly to a method for manufacturing a circuit board and a stepped groove for the circuit board without excess adhesive. Background Technology

[0002] As electronic devices develop towards multi-functionality, miniaturization, and lightweighting, electronic systems place increasingly higher demands on the performance of circuit boards. In particular, to achieve multi-functionality, it is necessary to integrate multi-layer circuit boards into a single circuit board and create stepped slots in the middle of the circuit board to realize the miniaturization, multi-functionality, and lightweighting of electronic devices.

[0003] For stepped slots on circuit boards, the commonly used methods are embedded gaskets and adhesive tape. However, the existing adhesive tape method is limited by the thickness of the copper at the bottom of the stepped slot. When the copper at the bottom of the stepped slot is thick, the tape cannot fill the height difference between the copper surface and the substrate area, resulting in significant adhesive residue at the bottom of the slot. Furthermore, this method is difficult to open, making it unsuitable for manufacturing stepped slots with a large copper thickness at the bottom. The embedded gasket method can solve the problems of difficult opening and limitation by the copper thickness at the bottom of the stepped slot, but the existing gasket method has the problem of adhesive overflow in the stepped slot.

[0004] Therefore, how to prepare stepped grooves for circuit boards without excess adhesive has become an urgent problem to be solved. Summary of the Invention

[0005] This invention provides a method for manufacturing a circuit board and a stepped groove for the circuit board without excess adhesive, in order to solve the problem of excess adhesive in the stepped groove of the circuit board.

[0006] According to one aspect of the present invention, a method for manufacturing a stepped groove on a circuit board without excess adhesive is provided, comprising:

[0007] Multiple core boards and multiple prepregs are available;

[0008] Grooves are made at at least a portion of the core board at a first preset position and at at least a portion of the prepreg at a second preset position, respectively, to form a first through hole in at least a portion of the core board and a second through hole in at least a portion of the prepreg;

[0009] Provide a resist film that at least covers the sidewalls of the second through-holes in each of the prepregs;

[0010] The core boards and the prepregs are stacked in a predetermined order; wherein the core boards and the prepregs are stacked alternately, and the first through hole of each core board communicates with the second through hole of each prepreg to form a communicating groove.

[0011] A sub-board is disposed on the side of the outermost prepreg away from the core board;

[0012] The core boards, the prepreg sheets, and the daughter boards are pressed together to form a mother board;

[0013] The motherboard at the connecting slot is milled with controlled depth to obtain the stepped slot of the circuit board.

[0014] Optionally, a resist film is provided that at least covers the sidewalls of the second through-holes in each of the prepregs, including:

[0015] The adhesive resist film is provided; the width of the adhesive resist film is greater than the thickness of the prepreg; wherein the adhesive resist film includes a first portion and a second portion located on opposite sides of the first portion and connected to the first portion;

[0016] The first portion of the resist film is attached to the sidewall of the second through hole in the prepreg;

[0017] The resist film is vacuum pre-pressed so that the second portion of the resist film covers at least a portion of the upper surface and at least a portion of the lower surface of the prepreg adjacent to the sidewall of the second through hole; wherein the upper surface and the lower surface are located on opposite sides of the sidewall of the second through hole.

[0018] Optionally, the width W1 of the first portion of the resist film is greater than or equal to the thickness D of the prepreg; the width W2 of the second portion of the resist film is greater than zero; wherein, 0mil < W1 + W2 - D < 10mil.

[0019] Optionally, the resist film includes a copper foil; the width of the copper foil is greater than the thickness of the prepreg.

[0020] Optionally, the resist film further includes a copper grid; at least a portion of the copper grid is located on opposite sides of the copper foil;

[0021] The copper foil at least covers the sidewall of the second through hole; the copper mesh at least covers the upper surface and the lower surface.

[0022] Optionally, the width W3 of the grid copper is greater than the width W4 of the copper foil; the difference between the width W3 of the grid copper and the width W4 of the copper foil is: 8mil ≤ W3 - W4 ≤ 14mil.

[0023] Optionally, the resist film includes copper foil and copper mesh;

[0024] A resist film is provided that at least covers the sidewalls of the second through-holes in each of the prepregs, including:

[0025] The copper foil is provided and attached to the sidewall of the second through hole in the prepreg; wherein the copper foil at least covers the sidewall of the second through hole in the prepreg.

[0026] The grid copper is provided and attached to the surface of the copper foil; wherein the width of the grid copper is greater than the width of the copper foil;

[0027] The copper mesh is vacuum pre-pressed so that it covers at least a portion of the upper surface and at least a portion of the lower surface of the copper foil and the prepreg adjacent to the sidewall of the second through hole, respectively; wherein the upper surface and the lower surface are located on opposite sides of the sidewall of the second through hole.

[0028] Optionally, the resist film includes copper foil and copper mesh;

[0029] A resist film is provided that at least covers the sidewalls of the second through-holes in each of the prepregs, including:

[0030] Provide the copper foil and the grid copper; attach the copper foil to one side of the grid copper to form the resist film; wherein the projection of the grid copper in the thickness direction of the resist film covers the projection of the copper foil in the thickness direction of the resist film, and a portion of the projection of the grid copper in the thickness direction of the resist film is located on opposite sides of the projection of the copper foil in the thickness direction of the resist film.

[0031] One side surface of the copper foil in the resist film is attached to the sidewall of the second through hole in the prepreg; wherein the copper foil at least covers the sidewall of the second through hole in the prepreg;

[0032] The resist film is vacuum pre-pressed so that the copper mesh in the resist film covers at least a portion of the upper surface and at least a portion of the lower surface of the prepreg adjacent to the sidewall of the second through hole; wherein the upper surface and the lower surface are located on opposite sides of the sidewall of the second through hole.

[0033] Optionally, before the sub-board is disposed on the side of the outermost prepreg away from each of the core boards, the following steps are included:

[0034] A gasket is placed inside the communicating groove; wherein the thickness of the gasket is the same as the depth of the communicating groove;

[0035] After milling the mother plate at the connecting slot with controlled depth, the process includes:

[0036] The gasket is removed by opening the cover to obtain the stepped groove of the circuit board. According to another aspect of the invention, a circuit board is provided, the circuit board including a stepped groove, the stepped groove being manufactured using the above-described method for manufacturing a stepped groove of a circuit board without excess adhesive.

[0037] The technical solution of this invention reduces the depth error of the stepped groove by slotting the core board and prepreg before pressing the template, avoiding the large error caused by drilling after pressing the template. By setting a resist film on the sidewall of the second through hole in the prepreg, the resin in the prepreg can be prevented from flowing into the bottom of the stepped groove during the pressing process, thus avoiding damage to the circuit pattern at the bottom of the groove and achieving the production of a stepped groove for the circuit board without glue overflow. Moreover, the resist film is located on the sidewall of the second through hole and does not need to be removed separately, which reduces the manufacturing process and lowers the manufacturing cost while avoiding residue at the bottom of the groove.

[0038] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A flowchart illustrating a method for manufacturing a non-overflowing adhesive stepped groove on a circuit board according to Embodiment 1 of the present invention;

[0041] Figure 2 A process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 1 of the present invention;

[0042] Figure 3 A flowchart illustrating a method for manufacturing a non-overflowing adhesive stepped groove on a circuit board according to Embodiment 2 of the present invention;

[0043] Figure 4 This is a partial process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 2 of the present invention;

[0044] Figure 5 A flowchart illustrating a method for manufacturing a non-overflowing adhesive stepped groove on a circuit board according to Embodiment 3 of the present invention;

[0045] Figure 6 This is a partial process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 3 of the present invention;

[0046] Figure 7 A flowchart illustrating a method for manufacturing a non-overflowing adhesive stepped groove on a circuit board according to Embodiment 4 of the present invention;

[0047] Figure 8This is a partial process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 4 of the present invention;

[0048] Figure 9 A flowchart illustrating a method for manufacturing a non-overflowing adhesive stepped groove on a circuit board according to Embodiment 5 of the present invention;

[0049] Figure 10 This is a partial process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 5 of the present invention;

[0050] Figure 11 This is a schematic diagram of a circuit board provided in Embodiment Six of the present invention. Detailed Implementation

[0051] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0053] Example 1

[0054] Figure 1 This is a flowchart illustrating a method for manufacturing a stepped groove on a circuit board without excess adhesive, as provided in Embodiment 1 of the present invention. This embodiment is applicable to the manufacturing of stepped grooves on circuit boards. Figure 1 As shown, the method includes:

[0055] S1001 provides multiple core boards and multiple prepregs.

[0056] In this context, the core board refers to the printed circuit board located inside a multilayer circuit board, and it contains the circuit patterns. Prepreg, also known as PP (prepreg) sheet, is mainly composed of resin and fiberglass, and is typically placed between two circuit boards to isolate and bond them together.

[0057] S1002. Grooves are made at a first preset position in at least a portion of the core board and at a second preset position in at least a portion of the prepreg, respectively, to form a first through hole in at least a portion of the core board and a second through hole in at least a portion of the prepreg.

[0058] The first preset position corresponds to the second preset position. For example, a groove is made at the first preset position of a portion of the core board to form a first through hole; a groove is made at the second preset position of a portion of the prepreg to form a second through hole. It should be noted that the embodiments of the present invention do not limit the process used for grooving.

[0059] S1003. Provide an adhesive resist film that at least covers the sidewall of the second through hole in each semi-cured sheet.

[0060] Specifically, a resist film is attached to the sidewall of the second through-hole in the prepreg, ensuring that the resist film at least covers the sidewall of the second through-hole in the prepreg. In addition, the resist film can also cover other surfaces of the second through-hole in the prepreg. The resist film has a certain degree of rigidity to prevent resin from overflowing from the prepreg during extrusion.

[0061] In an optional embodiment, the second through hole may be slightly larger than the first through hole, so that a certain space can be reserved for the resist film, so that the size of the second through hole after the resist film is attached is the same as the size of the first through hole, thereby improving the flatness of the first through hole and the second through hole after the resist film is attached.

[0062] S1004. Stack the core boards and prepregs in a predetermined order.

[0063] Specifically, the core boards and the prepregs are stacked alternately, and the core boards with first through holes and the prepregs with second through holes are placed adjacent to each other. The first through holes and the second through holes correspond to each other, and the first through holes of each core board and the second through holes of each prepreg are connected to form a connecting groove.

[0064] In an optional embodiment, the conductive lines of the core boards may be browned before the core boards and prepregs are stacked in a predetermined order to increase the bonding strength between the core boards and the prepregs.

[0065] S1005. A sub-board is installed on the side of the outermost prepreg away from the core board.

[0066] In this context, a daughterboard refers to the outermost circuit board in a multilayer circuit board. The daughterboard includes a conductive layer that is not patterned. For example, the daughterboard can be a copper-clad board without any circuit patterns.

[0067] S1006. Press each core board, each prepreg and daughter board together to form a mother board.

[0068] Specifically, the core board, each semi-cured sheet, and the daughter board can be pressed together at high temperature under certain conditions to form the mother board.

[0069] S1007. Perform controlled-depth milling on the motherboard at the connecting slot to obtain the stepped slot of the circuit board.

[0070] Specifically, the sub-board covering the surface of the connecting slot is milled with controlled depth. After milling off the sub-board on the surface of the connecting slot, the stepped slot of the circuit board can be obtained.

[0071] For example, Figure 2 This is a process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 1 of the present invention, with reference to... Figure 1 and Figure 2 First, slots are cut at the first preset position 11 of a portion of the core board 110 and the second preset position 21 of a portion of the prepreg 210 to obtain a first through hole 011 and a second through hole 021. Second, a resist film 30 is attached to the sidewall 201 of the second through hole 021, and the conductive lines of the core board are browned. Then, the core board 110 with the first through hole 011 and the prepreg 120 with the second through hole 021 are placed adjacent to each other, and the core board 110 without the first through hole 011 and the prepreg 120 without the second through hole 021 are placed adjacent to each other. At the same time, all the core boards 110 and prepregs 210 are stacked alternately, so that the first through hole 011 and the second through hole 021 can communicate and form a connecting groove. 001; Next, a sub-board 410 is placed on the side of the outermost prepreg 210 sheet away from the core board 110 to avoid damage to the circuit pattern of the core board 110 in subsequent processes. The core boards 110, the prepreg sheets 210 and the sub-board 410 are pressed together at high temperature to form the mother board 10. The prepreg sheet 210 is in a molten state during the high temperature pressing process. The adhesive-resistant film 30 set on the side wall 201 of the second through hole 021 can prevent the resin adhesive in the prepreg sheet 210 from flowing into the bottom of the connecting groove 001, thus avoiding damage to the circuit pattern 111 at the bottom of the groove. Finally, the sub-board 410 covering the surface of the connecting groove 001 is milled with controlled depth. After milling off the sub-board 410 on the surface of the connecting groove 001, a stepped groove 002 is obtained.

[0072] Understandably, after forming the motherboard, through-holes can be drilled into it. Copper plating and electroplating can then be applied to these through-holes to create metallized vias, which can be used as connectors. After creating the metallized vias, the conductive layer of the daughterboard can be patterned to form the outer layer circuit pattern, and solder resist can be applied after this process. The circuit board with the stepped grooves can undergo surface treatments, such as anti-oxidation treatment, and further processing can be performed, which will not be elaborated upon here.

[0073] In this embodiment of the invention, by slotting the core board and prepreg before pressing the template, the depth error of the stepped groove can be reduced, avoiding the large error caused by drilling after pressing the template. By setting a resist film on the sidewall of the second through hole in the prepreg, the resin in the prepreg can be prevented from flowing into the bottom of the stepped groove during the pressing process, thus avoiding damage to the circuit pattern at the bottom of the groove and realizing the production of a stepped groove for the circuit board without glue overflow. Moreover, the resist film is located on the sidewall of the second through hole and does not need to be removed separately. This not only avoids residue at the bottom of the groove but also reduces the manufacturing process and lowers the manufacturing cost.

[0074] Example 2

[0075] Figure 3 This is a flowchart illustrating a method for manufacturing a non-overflowing stepped groove for a circuit board according to Embodiment 2 of the present invention. Compared to the above embodiments, this embodiment adds a gasket to the connecting groove during the pressing of the motherboard to completely solve the problem of overflowing adhesive at the bottom of the groove. Figure 3 As shown, the method includes:

[0076] S2001 provides multiple core boards and multiple prepregs.

[0077] S2002, Grooves are made at at least a portion of the core board at a first preset position and at at least a portion of the prepreg at a second preset position, respectively, to form a first through hole in at least a portion of the core board and a second through hole in at least a portion of the prepreg.

[0078] S2003. Provide an adhesive resist film that at least covers the sidewall of the second through hole in each semi-cured sheet.

[0079] S2004. Stack the core boards and prepregs in the predetermined order.

[0080] S2005. Place a gasket in the connecting groove.

[0081] The thickness of the gasket is the same as the depth of the connecting groove. The gasket may include, for example, a PTFE (polytetrafluoroethylene) gasket, or other types of gaskets; this embodiment of the invention does not limit the types of gaskets used.

[0082] S2006. A sub-board is installed on the side of the outermost prepreg away from the core board.

[0083] S2007. Press each core board, each prepreg and daughter board together to form a mother board.

[0084] S2008. Perform controlled-depth milling on the motherboard at the connecting slot, open the cover and remove the gasket to obtain the stepped slot of the circuit board.

[0085] For example, Figure 4 This is a partial process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 2 of the present invention, for reference. Figure 3 and Figure 4 Before placing the sub-board 410 on the side of the outermost semi-cured sheet 210 away from the core board, a PTFE gasket 50 is placed in the connecting groove 001. Then, the sub-board 410 is placed on the side of the outermost semi-cured sheet 210 away from the core board 110, embedding the PTFE gasket 50 within the accommodating space formed by the sub-board 410, the core board 110, and the semi-cured sheet 210. Pressing the sub-board 410, the core board 110, the semi-cured sheet 210, and the PTFE gasket 50 together yields the mother board 10. By milling a groove in the mother board 10 with controlled depth, the cover (sub-board 410) above the PTFE gasket 50 can be milled off. Then, the remaining PTFE gasket 50 is removed to obtain the stepped groove 002.

[0086] In this embodiment of the invention, by placing a gasket in the connecting groove before setting the sub-board on the side of the outermost prepreg away from each core board, a gasket can be placed in the connecting groove during the pressing of the motherboard. In this way, the gasket can block the adhesive resist film during the pressing of the motherboard, preventing the adhesive resist film from being squeezed and falling off, and preventing adhesive overflow at the bottom of the stepped groove. In addition, placing a gasket in the connecting groove can reduce the depth error when controlling the depth of the groove during milling of the motherboard, and prevent large milling errors from damaging the circuit pattern at the bottom of the groove.

[0087] Example 3

[0088] Figure 5 This is a flowchart illustrating a method for fabricating a stepped groove on a circuit board without adhesive overflow, as provided in Embodiment 3 of the present invention. Compared to the above embodiments, this embodiment refines the details regarding the provision of a resist film that at least covers the sidewalls of the second through-holes in each prepreg. Figure 5 As shown, the method includes:

[0089] S3001 provides multiple core boards and multiple prepregs.

[0090] S3002, Grooves are made at at least a portion of the core board at a first preset position and at at least a portion of the prepreg at a second preset position, respectively, to form a first through hole in at least a portion of the core board and a second through hole in at least a portion of the prepreg.

[0091] S3003, Provide a resist film; the width of the resist film is greater than the thickness of the prepreg; wherein the resist film includes a first part and a second part located on opposite sides of the first part and connected to the first part.

[0092] S3004. Attach the first part of the resist film to the sidewall of the second through hole in the prepreg.

[0093] S3005, Vacuum pre-compression of the resist film, such that a second portion of the resist film covers at least a portion of the upper surface and at least a portion of the lower surface of the prepreg adjacent to the sidewall of the second through hole.

[0094] The upper and lower surfaces are located on opposite sides of the sidewall of the second through hole.

[0095] S3006. Stack the core boards and prepregs in the predetermined order.

[0096] S3007. A sub-board is installed on the side of the outermost prepreg away from the core board.

[0097] S3008. Press each core board, each prepreg and daughter board together to form a mother board.

[0098] S3009. Perform controlled-depth milling on the motherboard at the connecting slot to obtain the stepped slot of the circuit board.

[0099] For example, Figure 6 This is a partial process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 3 of the present invention, for reference. Figure 5 and Figure 6 The first part 31 of the resist film 30 is located between the second part 32. The first part 31 of the resist film 30 is attached to the side wall 201 of the second through hole 021. The resist film 30 can be vacuum pre-pressed by a high-speed press, so that the second part 32 of the resist film 30 is attached to part of the upper surface 202 and part of the lower surface 203 of the prepreg 210. The resist film 30 and the prepreg 210 can also be pressed into a whole.

[0100] In this invention, by providing a resist film with a width greater than the thickness of the prepreg, the second part of the resist film can be attached to the upper surface and part of the lower surface of the prepreg. This increases the area of ​​the resist film attached to the prepreg, increases friction, prevents the resist film from falling off the prepreg when pressing the motherboard, improves reliability, and facilitates the creation of a step groove for the circuit board without adhesive overflow.

[0101] Optional, continue to refer to Figure 6 The width W1 of the first part 31 of the resist film 30 is greater than or equal to the thickness D of the prepreg 210, and the width W2 of the second part 32 of the resist film 30 is greater than or equal to 0, and 0mil < W1 + W2 - D < 10mil.

[0102] For example, when the resist film 30 is attached to the prepreg 210, the first part 31 can completely cover the sidewall 201 of the second through hole 021, and the second part 32 can be attached to the upper surface 202 and the lower surface 203 respectively. The width of the resist film 30 attached to the upper surface 202 or the lower surface 203 is less than 10 mil. In this way, on the one hand, the resist film 30 is not easy to fall off, and on the other hand, the resist film 30 is not too wide, which would affect the inner layer circuit pattern on the core board when forming the motherboard.

[0103] Optionally, the resist film includes copper foil; the width of the copper foil is greater than the thickness of the prepreg. For example, both the first and second portions of the resist film may be copper foil, preventing resin in the prepreg from overflowing from the sidewalls, upper surface, and lower surface of the second through-hole.

[0104] Optionally, the resist film also includes a grid of copper; at least a portion of the grid of copper is located on opposite sides of the copper foil; wherein the copper foil at least covers the sidewall of the second via; and the grid of copper at least covers the upper and lower surfaces.

[0105] For example, the mesh copper and copper foil can be an integral structure, such as by forming the mesh copper by punching holes in a portion of the copper foil. A resist film is formed by attaching the un-punched area of ​​the copper foil to the sidewall of the second through-hole in the prepreg and attaching the punched area (mesh copper) of the copper foil to at least a portion of the upper surface and at least a portion of the lower surface adjacent to the sidewall of the second through-hole. This increases the roughness of the resist film attachment, increases the resist film's resistance to compression, and improves reliability.

[0106] Optionally, the width W3 of the grid copper is greater than the width W4 of the copper foil; the difference between the width W3 of the grid copper and the width W4 of the copper foil is: 8mil ≤ W3 - W4 ≤ 14mil.

[0107] For example, the grid copper and the copper foil are not a single structure. The width W3 of the grid copper is equal to the sum of the width W1 of the first part 31 and the width W2 of the two second parts 32. The width W4 of the copper foil can be the same as the width W1 of the first part 31. For example, the width W4 of the copper foil and the width W1 of the first part 31 are both the thickness D+6mil of the prepreg 210. When the resist film is attached to the prepreg 210, the copper foil can cover the sidewall 201 of the second through hole 021 and extend to the upper surface 201 and the lower surface 202 respectively, covering a width of 3mil. This can prevent the resin in the prepreg 210 from overflowing from the sidewall 201 of the second through hole 021, as well as the upper surface 202 and the lower surface 203. The part of the grid copper that is more than the copper foil can be the second part 32, W3-W4=2*W2, that is, 4mil≤W2≤7mil. When the resist film is attached to the prepreg 210, the grid copper can cover the copper foil and extend to the upper surface 201 and the lower surface 202 respectively, covering a width of 4-7mil. This can increase the roughness of the resist film attachment, increase the resist film's resistance to extrusion, and improve reliability.

[0108] Example 4

[0109] Figure 7 This is a flowchart illustrating a method for fabricating a stepped groove on a circuit board without adhesive overflow, as provided in Embodiment 4 of the present invention. Compared to the above embodiments, this embodiment details a case concerning the setting of the adhesive resist film when the resist film includes copper foil and copper mesh. For example... Figure 7 As shown, the method includes:

[0110] S4001 provides multiple core boards and multiple prepregs.

[0111] S4002. Grooves are made at a first preset position in at least a portion of the core board and at a second preset position in at least a portion of the prepreg, respectively, to form a first through hole in at least a portion of the core board and a second through hole in at least a portion of the prepreg.

[0112] S4003. Provide copper foil and attach the copper foil to the sidewall of the second through hole in the prepreg; wherein the copper foil at least covers the sidewall of the second through hole in the prepreg.

[0113] S4004. Provide a grid copper, and attach the grid copper to the surface of the copper foil; wherein the width of the grid copper is greater than the width of the copper foil.

[0114] S4005, vacuum pre-pressed copper mesh, such that the copper mesh covers at least a portion of the upper surface and at least a portion of the lower surface of the copper foil and the prepreg adjacent to the sidewall of the second through hole, respectively.

[0115] S4006. Stack the core boards and prepregs in the predetermined order.

[0116] S4007. A sub-board is installed on the side of the outermost prepreg away from the core board.

[0117] S4008. Press each core board, each prepreg and daughter board together to form a mother board.

[0118] S4009. Perform controlled-depth milling on the motherboard at the connecting slot to obtain the stepped slot of the circuit board.

[0119] For example, Figure 8 This is a partial process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 4 of the present invention, with reference to... Figure 7 and Figure 8 First, copper foil 33 can be set on the side wall 201 of the second through hole 021. After setting the copper foil 33, grid copper 34 can be set on the surface of the copper foil 33 and part of the upper surface 202 and part of the lower surface 203. Finally, the resist film 30 is vacuum pre-pressed by a fast press so that the grid copper 34 covers part of the upper surface 202 and part of the lower surface 203 of the copper foil 33 and the prepreg 210 respectively, and the resist film 30 and the prepreg 210 are pressed into a whole.

[0120] In this embodiment of the invention, copper foil is set with lines, and then a grid of copper is set so that the grid of copper can cover the copper foil as well as part of the upper and lower surfaces, which can prevent the copper foil from falling off and increase the copper foil's resistance to compression.

[0121] Example 5

[0122] Figure 9 This is a flowchart illustrating a method for fabricating a stepped groove on a circuit board without adhesive overflow, as provided in Embodiment 5 of the present invention. Compared to the above embodiments, this embodiment details another case regarding the setting of the adhesive resist film when the resist film includes copper foil and copper mesh. Figure 9 As shown, the method includes:

[0123] S5001 provides multiple core boards and multiple prepregs.

[0124] S5002, Grooves are made at at least a portion of the core board at a first preset position and at at least a portion of the prepreg at a second preset position, respectively, to form a first through hole in at least a portion of the core board and a second through hole in at least a portion of the prepreg.

[0125] S5003, Provide copper foil and grid copper; attach the copper foil to one side of the grid copper to form a resist film.

[0126] The projection of the grid copper in the thickness direction of the resist film covers the projection of the copper foil in the thickness direction of the resist film, and a portion of the projection of the grid copper in the thickness direction of the resist film is located on opposite sides of the projection of the copper foil in the thickness direction of the resist film.

[0127] S5004. Attach one side surface of the copper foil in the resist film to the sidewall of the second through hole in the prepreg.

[0128] The copper foil at least covers the sidewall of the second through-hole in the prepreg.

[0129] S5005, Vacuum pre-compression of the resist film, such that the copper mesh in the resist film covers at least a portion of the upper surface and at least a portion of the lower surface of the prepreg adjacent to the sidewall of the second through hole.

[0130] The upper and lower surfaces are located on opposite sides of the sidewall of the second through hole.

[0131] S5006. Stack the core boards and prepregs in the predetermined order.

[0132] S5007. A sub-board is installed on the side of the outermost prepreg away from the core board.

[0133] S5008. Press each core board, each prepreg, and the daughter board together to form a mother board.

[0134] S5009. Perform controlled-depth milling on the motherboard at the connecting slot to obtain the stepped slot of the circuit board.

[0135] For example, Figure 10 This is a partial process flow diagram of a non-overflowing adhesive stepped groove for a circuit board provided in Embodiment 5 of the present invention, with reference to... Figure 9 and Figure 10 Before fabricating the stepped groove of the circuit board, copper foil 33 can be pre-attached to one side of the grid copper 34 to form a resist film 30. Then, during the subsequent fabrication of the stepped groove of the circuit board, one side of the copper foil 33 in the resist film 30 can be attached to the side wall 201 of the second through hole 021. In this way, while avoiding residue at the bottom of the groove, the number of steps in fabricating the stepped groove of the circuit board can be reduced, and production efficiency can be improved.

[0136] Example 6

[0137] Figure 11 This is a schematic diagram of a circuit board structure provided in Embodiment Six of the present invention, with reference to... Figure 11 The circuit 100 includes a stepped groove 002, wherein the stepped groove 002 can be manufactured using the method for manufacturing a stepped groove of a circuit board without excess adhesive in any embodiment of the present invention.

[0138] For example, refer to Figure 11 The circuit board 100 includes a core board 110, a daughter board 410 and a prepreg 210. The prepreg 210 is stacked alternately with the core board 110 or the daughter board 410. A resist film 30 is provided in the stepped groove of the prepreg 210. There is a circuit pattern 111 at the bottom of the stepped groove 002, and there is no excess adhesive at the bottom of the groove.

[0139] The circuit board provided in this embodiment of the invention adopts the method for manufacturing a stepped groove circuit board without excess adhesive provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0140] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0141] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for manufacturing a stepped groove on a circuit board without excess adhesive, characterized in that, include: Multiple core boards and multiple prepregs are available; Grooves are made at at least a portion of the core board at a first preset position and at at least a portion of the prepreg at a second preset position, respectively, to form a first through hole in at least a portion of the core board and a second through hole in at least a portion of the prepreg; A resist film is provided; the width of the resist film is greater than the thickness of the prepreg; wherein the resist film includes a first portion and a second portion located on opposite sides of the first portion and connected to the first portion; The first portion of the resist film is attached to the sidewall of the second through hole in the prepreg; The resist film is vacuum pre-pressed so that the second portion of the resist film covers at least a portion of the upper surface and at least a portion of the lower surface of the prepreg adjacent to the sidewall of the second through hole; wherein the upper surface and the lower surface are located on opposite sides of the sidewall of the second through hole; The core boards and the prepregs are stacked in a predetermined order; wherein the core boards and the prepregs are stacked alternately, and the first through hole of each core board communicates with the second through hole of each prepreg to form a communicating groove. A sub-board is disposed on the side of the outermost prepreg away from the core board; The core boards, the prepreg sheets, and the daughter boards are pressed together to form a mother board; The motherboard at the connecting slot is milled with controlled depth to obtain the stepped slot of the circuit board.

2. The method for manufacturing a stepped groove on a circuit board without excess adhesive according to claim 1, characterized in that, The width W1 of the first portion of the resist film is greater than or equal to the thickness D of the prepreg; the width W2 of the second portion of the resist film is greater than zero; wherein, 0mil < W1 + W2 - D < 10mil.

3. The method for manufacturing a stepped groove on a circuit board without excess adhesive according to claim 1, characterized in that, The resist film includes a copper foil; the width of the copper foil is greater than the thickness of the prepreg.

4. The method for manufacturing a non-overflowing adhesive stepped groove on a circuit board according to claim 3, characterized in that, The resist film also includes a copper grid; at least a portion of the copper grid is located on opposite sides of the copper foil; The copper foil at least covers the sidewall of the second through hole; the copper mesh at least covers the upper surface and the lower surface.

5. The method for manufacturing a non-overflowing adhesive stepped groove on a circuit board according to claim 4, characterized in that, The width W3 of the copper grid is greater than the width W4 of the copper foil; the difference between the width W3 of the copper grid and the width W4 of the copper foil is: 8mil ≤ W3 - W4 ≤ 14mil.

6. The method for manufacturing a stepped groove on a circuit board without excess adhesive according to claim 1, characterized in that, The resist film comprises copper foil and copper mesh; Providing the resist film includes: providing the copper foil and the copper mesh; The first portion of the resist film is attached to the sidewall of the second through-hole in the prepreg, and the resist film is pre-pressed under vacuum so that the second portion of the resist film covers at least a portion of the upper surface and at least a portion of the lower surface of the prepreg adjacent to the sidewall of the second through-hole, including: The copper foil is attached to the sidewall of the second through hole in the prepreg, wherein the copper foil at least covers the sidewall of the second through hole in the prepreg; The copper grid is attached to the surface of the copper foil; wherein the width of the copper grid is greater than the width of the copper foil. The grid copper is vacuum pre-pressed so that it covers at least a portion of the upper surface and at least a portion of the lower surface of the copper foil and the prepreg adjacent to the sidewall of the second through hole.

7. The method for manufacturing a stepped groove on a circuit board without excess adhesive according to claim 1, characterized in that, The resist film comprises copper foil and copper mesh; Providing the resist film includes: providing the copper foil and the grid copper; attaching the copper foil to one side of the grid copper to form the resist film; wherein the projection of the grid copper in the thickness direction of the resist film covers the projection of the copper foil in the thickness direction of the resist film, and a portion of the projection of the grid copper in the thickness direction of the resist film is located on opposite sides of the projection of the copper foil in the thickness direction of the resist film; The first portion of the resist film is attached to the sidewall of the second through-hole in the prepreg, and the resist film is pre-pressed under vacuum so that the second portion of the resist film covers at least a portion of the upper surface and at least a portion of the lower surface of the prepreg adjacent to the sidewall of the second through-hole, including: One side surface of the copper foil in the resist film is attached to the sidewall of the second through hole in the prepreg; wherein the copper foil at least covers the sidewall of the second through hole in the prepreg; The resist film is vacuum pre-pressed so that the copper mesh in the resist film covers at least a portion of the upper surface and at least a portion of the lower surface of the prepreg adjacent to the sidewall of the second through hole.

8. The method for manufacturing a stepped groove on a circuit board without excess adhesive according to claim 1, characterized in that, Before the sub-board is disposed on the side of the outermost prepreg away from each of the core boards, the following is included: A gasket is placed inside the communicating groove; wherein the thickness of the gasket is the same as the depth of the communicating groove; After milling the mother plate at the connecting slot with controlled depth, the process includes: Remove the gasket after opening the cover to obtain the stepped groove of the circuit board.

9. A circuit board, characterized in that, The circuit board includes a stepped groove, which is manufactured using the method for manufacturing a stepped groove of a circuit board without excess adhesive as described in any one of claims 1-8.

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