Drilling tool and processing method of conductive hole in circuit board

Abstract

The invention provides a drilling tool and a processing method of a conductive hole in a circuit board. The machining method comprises the steps that a drilling tool is arranged on one side of the circuit board, an electromagnetic induction control system is arranged on the other side of the circuit board, and the electromagnetic induction control system can generate magnetic force; a conductive material is arranged in the drilling tool, drilling is started, and generated sweeps are discharged out of the hole under the action of magnetic force; the conductive material flows out of the drilling tool, so that the conductive material is attached to the hole wall or the hole is filled with the conductive material; and curing the conductive material in the hole to obtain the conductive hole. On the premise that the conductive hole meeting the electrical requirement is manufactured, the processes of glue removal, black shadow removal and black hole removal are not needed, the processes are simplified, and a large number of chemical agents and water resources are saved.

Description

Technical Field

[0001] This application relates to the technical field of circuit boards, and particularly to a drilling tool and a method for processing conductive holes in a circuit board. Background Art

[0002] In the production process of circuit boards, different types of holes (such as plated through holes, blind holes, buried holes, etc.) are usually drilled by mechanical drilling or laser drilling to complete the positioning operation of subsequent processes of the product or the conduction of circuits.

[0003] In the mechanical drilling method, the drill bit rotates at high speed and generates high heat energy through intense friction, softening the resin and producing smear in the hole wall. During the smear removal process, a lot of acid-base chemical agents and a large amount of water are required for cleaning to ensure that there is no residual smear in the hole wall. Therefore, a large amount of industrial wastewater is generated, increasing the manufacturing cost.

[0004] After obtaining a smooth hole wall through smear removal, processes such as black hole / black shadow treatment, antioxidant treatment of hole copper, and metallization treatment of resin hole walls are required to form a conductive medium on the hole wall. During electroplating, the conductive medium can adhere flatly to the hole wall to form a dense coating, achieving the purpose of conduction. Both black hole / black shadow and electroplating require a large amount of chemical agents and equipment, with long and complex processes, and extremely high time and cost consumption. Summary of the Invention

[0005] In view of this, this application proposes a drilling tool and a method for processing conductive holes in a circuit board to reduce the processing flow of conductive holes, reduce the use of chemical reagents and water, thereby reducing costs and achieving environmental protection purposes.

[0006] An embodiment of this application proposes a drilling tool, which includes a drill shank and a drill bit connected to the drill shank. One end of the drill shank away from the drill bit is provided with a first opening, and the bottom wall part of the first opening is recessed towards the drill bit to form a channel. The channel penetrates into the drill bit, and the drill bit is provided with a second opening. A control door is provided between one end of the channel away from the first opening and the second opening, and the control door is used to control whether the channel is communicated with the second opening.

[0007] In one embodiment, a chip removal groove is formed by inwards recessing a part of the outer side wall of the drill bit.

[0008] In one embodiment, the drilling tool further includes a transition part, the drill shank and the drill bit are connected through the transition part, and the channel penetrates through the transition part.

[0009] An embodiment of this application proposes a method for processing conductive holes in a circuit board, which includes the following steps:

[0010] A drilling tool as described above is provided on one side of the circuit board, and an electromagnetic induction control system is provided on the other side of the circuit board. The electromagnetic induction control system includes an electromagnetic coil configured to generate magnetic force;

[0011] Conductive material is provided in the first opening and the channel of the drilling tool. The drilling tool is started to drill the circuit board, and the waste chips generated by drilling are discharged out of the hole under the action of the magnetic force of the electromagnetic coil;

[0012] Open the control gate to allow the conductive material to flow out of the second opening, so that the conductive material adheres to the hole wall or fills the hole;

[0013] Cure the conductive material in the hole to obtain the conductive hole.

[0014] In one embodiment, the conductive material includes conductive particles, an organic solvent, and an adhesive. The conductive particles include one or more of carbon black, graphite, and metal powder, and the metal powder includes one or more of copper, silver, nickel, and gold.

[0015] In one embodiment, the organic solvent includes polyol ether and / or acetone, and the adhesive includes epoxy resin and / or acrylic resin.

[0016] In one embodiment, the conductive material includes conductive particles and an adhesive. The conductive particles include one or more of copper, aluminum, silver, tin, and gold, and the adhesive includes epoxy resin.

[0017] In one embodiment, the processing method further includes: providing a suction device on the side of the circuit board facing away from the electromagnetic induction control system to suck the waste chips generated by drilling out of the hole.

[0018] In one embodiment, the electromagnetic induction control system further includes a power supply, a control switch, and a pulse capacitor electrically connected to the electromagnetic coil.

[0019] In one embodiment, the processing method further includes: grinding the cured conductive material.

[0020] The drilling tool of the present application can, while completing drilling, discharge the waste chips generated by drilling out of the hole under the action of the magnetic force generated by the electromagnetic coil. After the hole is formed, the conductive material in the drilling tool can flow out into the hole, adhere to the hole wall or fill the hole, and the drilling and metallization (or plugging) of the hole are completed in one step. The processing method of the conductive hole of the present application, on the premise of making a conductive hole that meets the electrical requirements, does not require the processes of degumming, black shadow, and black hole, which not only simplifies the process but also saves a large amount of chemical agents and water resources. Description of the Drawings

[0021] Figure 1 Schematic diagram of a drilling tool provided by an embodiment of the present application.

[0022] Figures 2 to 8 For an embodiment of the present application, the use of Figure 1 Cross-sectional view of a conductive hole processed in a circuit board using the drilling tool shown.

[0023] Figures 9 to 13 For another embodiment of the present application, the use of Figure 1 Cross-sectional view of a conductive hole processed in a circuit board using the drilling tool shown.

[0024] Description of main component symbols

[0025] Drilling tool 100

[0026] Drill shank 10

[0027] Drill edge 20

[0028] Transition part 30

[0029] Control gate 40

[0030] First opening 101

[0031] Channel 102

[0032] First part 1021

[0033] Second part 1022

[0034] Second opening 201

[0035] Circuit board 200

[0036] Conductive holes 21, 27

[0037] Conductive circuit layer 22

[0038] Dielectric layer 23

[0039] Conductive materials 24, 26

[0040] Seed layer 25

[0041] Electromagnetic induction control system 300

[0042] The following specific embodiments will further illustrate the embodiments of the present application in conjunction with the above drawings. Specific embodiments

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which the embodiments of this application belong. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the embodiments of this application.

[0044] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of this application are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will change accordingly.

[0045] It will be understood that when a layer is referred to as being "on" another layer, it can be directly on the other layer or there can be an intermediate layer therebetween. In contrast, when a layer is referred to as being "directly on" another layer, there is no intermediate layer.

[0046] The embodiments of this application are described herein with reference to cross-sectional views, which are schematic diagrams of idealized embodiments (and intermediate structures) of this application. Thus, differences in the shapes shown due to manufacturing processes and / or tolerances are foreseeable. Therefore, the embodiments of this application should not be construed as limited to the specific shapes of the regions shown herein, but should include, for example, deviations in shapes resulting from manufacturing. The regions shown in the figures are merely illustrative, their shapes are not intended to illustrate the actual shape of the device, and are not intended to limit the scope of this application.

[0047] The following will describe in detail some embodiments of this application with reference to the drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0048] Please refer to Figure 1 , a drilling tool 100 is provided in the first aspect of this application, which can be used to form conductive holes in a circuit board. The drilling tool 100 includes a drill shank 10 and a drill bit 20 connected to the drill shank 10. The drill shank 10 and the drill bit 20 are coaxially arranged. The drill shank 10 can be clamped by a machine tool (not shown in the figure), and the machine tool drives the clamped drill shank 10 to rotate at a high speed, thereby driving the drill bit 20 to rotate at a high speed. The drill bit 20 contacts the circuit board for friction and cutting, thereby forming a hole. The diameter of the hole can be 0.6 mm.

[0049] As Figure 1As shown, at one end of the drill shank 10 away from the drill bit 20, a first opening 101 is provided. The cross-section of the first opening 101 can be trapezoidal. Along the direction from the drill shank 10 to the drill bit 20, the width of the first opening 101 can decrease. A bottom wall portion of the first opening 101 is recessed towards the drill bit 20 to form a channel 102. The channel 102 penetrates through to the inside of the drill bit 20 along the height direction of the drilling tool 100, and the diameter of the channel 102 can be 0.3 mm. The drill bit 20 is provided with a second opening 201. A control gate 40 is provided between the end of the channel 102 away from the first opening 101 (located inside the drill bit 20) and the second opening 201 of the drill bit 20. The control gate 40 is used to control whether the channel 102 is in communication with the second opening 201. For example, when the control gate 40 is opened, the channel 102 is in communication with the second opening 201, so that the channel 102 can be in communication with the outside of the drilling tool 100; when the control gate 40 is closed, the channel 102 and the second opening 201 are not in communication due to the blocking of the control gate 40, and the channel 102 is not in communication with the outside of the drilling tool 100. Along the height direction of the drilling tool 100, the height of the control gate 40 can be 0.2 mm.

[0050] The conductive material can be added through the first opening 101 and flow into the channel 102. After the drill bit 20 finishes drilling, when the control gate 40 is opened, the conductive material can flow into the hole drilled by the drill bit 20 through the second opening 201.

[0051] As Figure 1 shown, in some embodiments, inside the drill bit 20, the end of the channel 102 (the end away from the first opening 101) can be divided into a first part 1021 and a second part 1022 inside the drill bit 20, so as to form a Y-shaped cross-section. The first part 1021 and the second part 1022 respectively extend towards the direction close to the second opening 201 of the drill bit 20, and the extension direction has a certain angle with the central axis direction of the drilling tool 100. A control gate 40 is provided between the first part 1021 and the second opening 201, and a control gate 40 is provided between the second part 1022 and the second opening 201.

[0052] As Figure 1 shown, in some embodiments, the drilling tool 100 further includes a transition portion 30. The drill shank 10 and the drill bit 20 are connected by the transition portion 30 to improve the overall strength of the drilling tool 100. It can be understood that the channel 102 penetrates through the transition portion 30. The transition portion 30 can be frustum-shaped, and its cross-sectional shape can be trapezoidal.

[0053] In some embodiments, a chip fluting groove (not shown in the figure) is formed by the inward depression of the outer wall portion of the drill bit 20.

[0054] Please refer to Figures 2 to 13, the second aspect of the present application provides a processing method for forming conductive holes 21 and 27 in a circuit board 200 using the above-mentioned drilling tool 100. The circuit board 200 is an electronic device formed with a conductive circuit layer, which can be a single-sided board, a double-sided board, a multi-layer circuit board, etc., or a rigid board, a flexible board, or a rigid-flex board, etc. The present application does not make any restrictions. The circuit board 200 includes at least one conductive circuit layer 22 and at least one dielectric layer 23. When the conductive circuit layer 22 is multi-layered, each dielectric layer 23 is disposed between two adjacent conductive circuit layers 22. The materials of the conductive circuit layer 22 and the dielectric layer 23 can be conventional or unconventional materials in the art, and the present application does not make any restrictions. The conductive circuit layer can be formed before or after the processing of the conductive holes 21 and 27 is completed.

[0055] The first embodiment

[0056] Please refer to Figures 2 to 8 , the processing method of the conductive hole 21 in the circuit board 200 includes steps S10 to S40. It can be understood that numbering the steps aims to clearly describe the specific preparation method and does not limit the sequence of the steps.

[0057] Step S10, as Figure 2 shown, along the thickness direction of the circuit board 200, a drilling tool 100 as Figure 1 shown (drill edge 20 is close to the circuit board 200) is disposed on one side of the circuit board 200, and an electromagnetic induction control system 300 is disposed on the other side of the circuit board 200. As Figure 3 shown, the electromagnetic induction control system 300 includes an electromagnetic coil, and the electromagnetic coil can generate a magnetic force. In this embodiment, the circuit board 200 includes two conductive circuit layers 22 and one dielectric layer 23. In other embodiments, the number of conductive circuit layers 22 can be increased or decreased.

[0058] In some embodiments, as Figure 3 shown, the electromagnetic induction control system 300 further includes a power supply, a control switch, and a pulse capacitor electrically connected to the electromagnetic coil to energize the electromagnetic coil, thereby generating a magnetic force. The power supply can be a high-voltage DC power supply. As Figure 3 shown, in some embodiments, the magnetic force generated after the electromagnetic coil is energized is upward. In other embodiments, the magnetic force generated after the electromagnetic coil is energized is downward. The direction of the magnetic force generated after the electromagnetic coil is energized should be consistent (parallel) with the direction of the electromagnetic induction control system 300 pointing to the drilling tool 100.

[0059] Step S20, as Figure 4As shown, a conductive material (not shown in the figure) is disposed in the first opening 101 and the channel 102 of the drilling tool 100. The drilling tool 100 is started to drill the circuit board 200. The drill bit 20 can rotate in a clockwise or counterclockwise direction. The waste chips generated by drilling are discharged out of the hole under the action of the magnetic force of the electromagnetic coil (the direction of the arrow in the figure). In this embodiment, the hole formed by the drill bit 20 is a through hole that penetrates the entire circuit board 200 in the thickness direction.

[0060] Specifically, after the electromagnetic coil is energized, a pulsed magnetic field (magnetic force) is generated under the current. An induced microcurrent is generated in the conductive circuit layer 22 in the circuit board 200, static electricity is generated on the dielectric layer 23 by the friction of the drill bit 20, and the waste chips generated by drilling (i.e., part of the conductive circuit layer 22 and the dielectric layer 23, which can be copper, resin, etc. respectively) are directionally transferred under the action of the electric field. By controlling the magnetic field range and the direction of the magnetic force, the waste chips generated by drilling can be discharged out of the hole.

[0061] In some embodiments, a suction device (not shown in the figure) can also be disposed on the side of the circuit board 200 facing away from the electromagnetic induction control system 300. That is, the suction device and the drilling tool 100 are located on the same side of the circuit board 200. When the drilling tool 100 is drilling, the suction device can be started to suck the hole drilled by the drill bit, generating a suction force, which helps to quickly discharge the waste chips generated by drilling.

[0062] After drilling is completed and all the waste chips are discharged, both the electromagnetic induction control system and the suction device can be turned off.

[0063] Step S30, as Figure 5 and Figure 6 shown, after drilling is completed, the control door 40 of the drilling tool 100 is opened (refer to Figure 1 ), so that the conductive material 24 flows out from the second opening 201 (refer to Figure 1 ), and thus adheres to the hole wall. By the high-speed rotation of the drill bit 20, the conductive material 24 can be evenly dispersed and adhered to the hole wall. In this embodiment, the conductive material 24 on the hole wall can be called a seed layer. By controlling the rotation speed of the drill bit 20 and the outflow amount of the conductive material 24, the thickness of the seed layer adhered to the hole wall can be controlled.

[0064] In this embodiment, the conductive material includes conductive particles, organic solvents, and adhesives. The conductive particles can be, but are not limited to, one or more of carbon black, graphite, and metal powder, and the conductive particles can be nano-conductive particles. The metal powder can be, but is not limited to, one or more of copper, silver, nickel, and gold.

[0065] Further, the organic solvent may be, but is not limited to, one or more of polyol ethers and acetone, and the binder may be, but is not limited to, one or more of epoxy resins and acrylic resins. The organic solvent and the binder can endow the conductive particles with a certain fluidity and viscosity, so that the conductive particles can smoothly flow out of the drilling tool 100 and adhere to the inside of the hole.

[0066] Further, the conductive material may also include additives such as stabilizers and dispersants.

[0067] Step S40, as Figure 7 shown, cure the conductive material 24 in the hole to form a seed layer 25, and obtain a conductive hole 21.

[0068] In some embodiments, as Figure 8 shown, the cured conductive material 24 (seed layer 25) may also be polished to remove the part of the seed layer 25 outside the conductive hole 21 and make the surface of the seed layer 25 flat.

[0069] In this embodiment, while the drilling tool 100 is drilling a hole, it can also discharge the waste chips generated by drilling out of the hole under the action of the magnetic force generated by the electromagnetic coil. After the hole is formed, the second opening 201 of the drilling tool 100 is opened to allow the conductive material 24 to flow out. The conductive material 24 can be evenly attached to the hole wall as the drilling tool 100 rotates, and drilling and metallization of the hole are completed in one step. This embodiment does not require the processes of desmearing, black shadow, and black hole, which not only simplifies the process but also saves a large amount of chemical agents and water resources. This embodiment is applicable to the fabrication of conductive vias or conductive blind holes with special requirements for conductivity.

[0070] Second Embodiment

[0071] This embodiment is applicable to the fabrication of ordinary conductive blind holes.

[0072] Step S10, please refer to Figure 2 , which is the same as that in the first embodiment and will not be elaborated here.

[0073] Step S20, please refer to Figure 9 , arrange a conductive material (not shown in the figure) in the first opening 101 (refer to Figure 1 ) and the channel 102 (refer to Figure 1 ) of the drilling tool 100, and start the drilling tool 100 to drill the circuit board 200. In this embodiment, the hole formed by the drill bit 20 is a blind hole, and the via penetrates one of the conductive circuit layers 22 and the dielectric layer 23 in the thickness direction, and a part of the surface of the other conductive circuit layer 22 can be exposed from the blind hole.

[0074] In some embodiments, a suction device (not shown in the figure) may also be provided on the side of the circuit board 200 facing away from the electromagnetic induction control system 300. That is, the suction device and the drilling tool 100 are located on the same side of the circuit board 200. When the drilling tool 100 drills a hole, the suction device can also be activated to suck the hole drilled by the drill edge, generating suction, which helps to quickly discharge the waste chips generated by drilling. After drilling is completed and all the waste chips are discharged, both the electromagnetic induction control system and the suction device can be turned off.

[0075] Step S30, please refer to Figure 10 and Figure 11 , after drilling is completed, open the control door 40 of the drilling tool 100 (refer to Figure 1 ), so that the conductive material 26 flows out from the second opening 201 (refer to Figure 1 ), to fill the blind hole (plug the hole).

[0076] In this embodiment, the conductive material 26 includes conductive particles and a binder. The conductive particles can be, but are not limited to, one or more of copper, aluminum, silver, tin, and gold, and the conductive particles can be surface-treated nano-conductive particles. The binder can be, but is not limited to, epoxy resin. In some embodiments, the conductive material 26 is also referred to as metal paste.

[0077] Furthermore, the conductive material 26 can also include additives such as stabilizers and dispersants.

[0078] Step S40, please refer to Figure 12 , cure the conductive material 26 in the blind hole to obtain a conductive hole 27.

[0079] In some embodiments, the conductive material 26 can be pre-cured at a temperature of 60°C for 30 minutes first, and then subjected to high-temperature baking at a temperature of 160°C for 1 hour until completely cured, so that the conductive material 26 in the blind hole forms a complete conductive circuit.

[0080] In some embodiments, please refer to Figure 13 , the cured conductive material 26 can also be ground to remove the part of the conductive material 26 outside the conductive hole 27.

[0081] In this embodiment, while the drilling tool 100 completes drilling, it can also discharge the waste chips generated by drilling under the action of the magnetic force generated by the electromagnetic coil outside the hole. After the hole is formed, the second opening 201 of the drilling tool 100 is opened, so that the conductive material 26 flows out, and the conductive material 26 can fill the blind hole, completing drilling and plugging the hole in one step. In this embodiment, there is no need for the processes of de-gluing, black shadow, and black hole, which not only simplifies the process but also saves a large amount of chemical agents and water resources.

[0082] While the drilling tool 100 of the present application is completing drilling, it can also discharge the waste chips generated by drilling out of the hole under the action of the magnetic force generated by the electromagnetic coil. After the hole is formed, the conductive materials 24 and 26 inside the drilling tool 100 can flow out into the hole, adhere to the hole wall or fill the hole, completing drilling and metallization (or plugging) of the hole in one step. The processing method of the conductive holes 21 and 27 of the present application, on the premise of making the conductive holes 21 and 27 that meet the electrical requirements, does not require the processes of degumming, black shadow, and black hole, which not only simplifies the process but also saves a large amount of chemical agents and water resources.

[0083] The above description is some specific embodiments of the present application, but in actual application, it cannot be limited to these embodiments only. For those of ordinary skill in the art, other deformations and changes made according to the technical concept of the present application should fall within the protection scope of the present application.

Claims

1. A drilling tool, comprising a drill shank and a drill edge connected to the drill shank, characterized in that, One end of the drill shank away from the drill blade is provided with a first opening, and a bottom wall portion of the first opening is recessed toward the drill blade to form a channel, the channel penetrates into the drill blade, the drill blade is provided with a second opening, and a control door is arranged between one end of the channel away from the first opening and the second opening, and the control door is used to control whether the channel is communicated with the second opening.

2. The drilling tool according to claim 1, characterized in that, A chip removal groove is formed by inwards recessing a part of the outer side wall of the drill blade.

3. The drilling tool according to claim 1, characterized in that The drilling tool further includes a transition portion, the drill shank and the drill blade are connected through the transition portion, and the channel penetrates through the transition portion.

4. A method for processing conductive vias in a circuit board, characterized in that, The processing method includes the following steps: The drilling tool according to any one of claims 1 to 3 is arranged on one side of the circuit board, and an electromagnetic induction control system is arranged on the other side of the circuit board. The electromagnetic induction control system includes an electromagnetic coil, and the electromagnetic coil is configured to generate magnetic force. A conductive material is arranged in the first opening and the channel of the drilling tool, the drilling tool is started to drill the circuit board, and the waste chips generated by drilling are discharged out of the hole under the action of the magnetic force of the electromagnetic coil. The control door is opened so that the conductive material flows out from the second opening, and the conductive material is attached to the hole wall or fills the hole. The conductive material in the hole is cured to obtain the conductive hole.

5. The processing method according to claim 4, characterized in that, The conductive material includes conductive particles, an organic solvent and an adhesive; the conductive particles include one or more of carbon black, graphite, and metal powder, and the metal powder includes one or more of copper, silver, nickel, and gold.

6. The processing method according to claim 5, characterized in that The organic solvent includes polyol ether and / or acetone, and the adhesive includes epoxy resin and / or acrylic resin.

7. The processing method according to claim 4, characterized in that The conductive material includes conductive particles and an adhesive, the conductive particles include one or more of copper, aluminum, silver, tin, and gold, and the adhesive includes epoxy resin.

8. The processing method according to claim 4, wherein The processing method further includes: arranging a suction device on a side of the circuit board facing away from the electromagnetic induction control system to suck the waste chips generated by drilling out of the hole.

9. The processing method according to claim 4, characterized in that The electromagnetic induction control system further includes a power supply, a control switch and a pulse capacitor electrically connected to the electromagnetic coil.

10. The processing method according to claim 4, characterized in that, The processing method further includes: grinding the cured conductive material.

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