CN113286429A - Back drill manufacturing method - Google Patents
Back drill manufacturing method Download PDFInfo
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- CN113286429A CN113286429A CN202010762656.2A CN202010762656A CN113286429A CN 113286429 A CN113286429 A CN 113286429A CN 202010762656 A CN202010762656 A CN 202010762656A CN 113286429 A CN113286429 A CN 113286429A
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- conductive
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- rod section
- conductive layer
- back drilling
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/0011—Working of insulating substrates or insulating layers
- H05K3/0044—Mechanical working of the substrate, e.g. drilling or punching
- H05K3/0047—Drilling of holes
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/02—Details related to mechanical or acoustic processing, e.g. drilling, punching, cutting, using ultrasound
- H05K2203/0207—Partly drilling through substrate until a controlled depth, e.g. with end-point detection
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- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
- Production Of Multi-Layered Print Wiring Board (AREA)
Abstract
The invention relates to the technical field of PCBs (printed circuit boards), and discloses a back drilling manufacturing method, which comprises the following steps: providing a multilayer board; the multilayer board includes: the hole wall is provided with a first metalized through hole of a first conductive layer, a second metalized through hole of a second conductive layer and a third conductive layer; controlling the composite drill cutter to back drill at the position of the first metalized through hole; the composite drill bit sequentially comprises a first outer insulating part, an outer conductive part and a second insulating part from the cutting front end to the cutting rear end; the outer conductive part is electrically connected with the middle electric connection unit; the outer conductive part, the third conductive layer, the second conductive layer, the middle electric connection unit and the outer conductive part are sequentially connected to form a switch control loop; and in the back drilling process, when the switching of the states of open circuit, short circuit, open circuit and short circuit is detected to be formed in the switch control loop in sequence, the back drilling is controlled to stop. According to the invention, the back drilling depth can be accurately controlled by a mode of controlling the back drilling to stop when the state of the switch control loop is recognized to be converted, and the drilling depth control precision is effectively improved.
Description
Technical Field
The invention relates to the technical field of Printed Circuit Boards (PCBs), in particular to a back drill manufacturing method.
Background
With the development of wireless network communication technology, the signal transmission rate is higher and higher. PCBs are important components of signal transmission, in which Stub (extra via copper) length of a signal via is one of key indexes.
Stub acts like a redundant "tail" in the transmission line, acting as a notch filter; when there are two such stubs present in the signal transmission line, an oscillating section will be formed. Regardless of filtering or oscillation, it will cause damage to the transmission of high speed signals, causing signal distortion, so it is important to improve the back drilling precision to shorten the Stub length.
Currently, backdrilling is generally performed by the following two methods:
the first back drilling method comprises the following steps: firstly, manufacturing a metalized through hole on a PCB, then stacking an aluminum sheet on the back drilling surface of the PCB, then controlling a drill cutter positioned above the metalized through hole to move downwards, and controlling the drill cutter to continue to move downwards for a preset theoretical drilling depth value after detecting that a drill bit of the drill cutter is in contact with the aluminum sheet, thus completing back drilling.
The second back drilling method comprises the following steps: after the PCB with the prepared metallized through hole is placed on a drill floor, the required descending distance of the drill is calculated according to the actual height from the drill positioned at the original position to the drill floor, the preset theoretical drilling depth and the thickness of the PCB, and then the drill is controlled to descend by the corresponding distance according to the calculation result, so that the back drilling is completed.
Due to the processing accuracy, etc., there may be a difference in board thickness between PCBs produced in different batches, between PCBs produced in the same batch, and different regions of the same PCB. However, both of the above-mentioned back drilling methods perform back drilling depth control using the same command to produce back drilled holes having the same preset theoretical drilling depth, and the above-mentioned plate thickness difference phenomenon is not considered, thereby causing a large deviation in Stub of each back drilled hole.
Disclosure of Invention
The invention aims to provide a back drill manufacturing method, which reduces the influence of the plate thickness difference on the depth control precision of the back drill.
In order to achieve the purpose, the invention adopts the following technical scheme:
a back drilling manufacturing method comprises the following steps:
providing a multilayer board; the multilayer sheet includes: the hole wall is provided with a first metalized through hole of a first conductive layer, a second metalized through hole of a second conductive layer and a third conductive layer; on the back drilling surface of the multilayer board, the first conducting layer is electrically connected with the second conducting layer through surface copper;
the third conducting layer is positioned on one back drilling penetrating layer of the multilayer board and is formed on the periphery of the first metalized through hole; the third conductive layer is electrically connected with the first conductive layer and the second conductive layer respectively; the second conducting layer is also electrically connected with a middle electric connection unit positioned outside the multilayer board;
controlling a composite drill to perform back drilling at the position of the first metalized through hole;
wherein the composite drill bit comprises: the cutting tool comprises a first outer insulation part, an outer conductive part and a second outer insulation part, wherein the first outer insulation part is positioned at the front end of cutting and at least provided with an insulated outer surface, the outer conductive part is positioned at the middle end of cutting and at least provided with an insulated outer surface, the second outer insulation part is positioned at the rear end of cutting and at least provided with an insulated outer surface, the diameter of the radial section of the outer conductive part is not smaller than that of the first outer insulation part, and the axial height of the outer conductive part is smaller than the distance from the third conductive layer to the back drilling surface; the outer conductive part is electrically connected with the intermediate electric connection unit; the outer conductive part, the third conductive layer, the second conductive layer, the intermediate electrical connection unit and the outer conductive part are sequentially connected to form a switch control loop;
in the back drilling process, detecting the state of the switch control loop in real time after the composite drill bit starts to contact a back drilling surface; and when detecting that the switch control loop forms the state switching of a first open circuit state, a first short circuit state, a second open circuit state and a second short circuit state in sequence, controlling the composite drill cutter to stop back drilling.
Optionally, the third conductive layer is located on a back-drilled through layer of the multilayer board adjacent to the back-drilled non-through layer;
the controlling the composite drill bit to stop back drilling comprises: and controlling the composite drill to stop moving immediately or stop moving in a delayed manner.
Optionally, the third conductive layer is located on any back-drilled penetrating layer of the multilayer board that is not adjacent to the back-drilled non-penetrating layer;
the controlling the composite drill bit to stop back drilling comprises: and controlling the composite drill cutter to stop moving in a delayed manner.
Optionally, the composite drill specifically includes: a drill bit, a cutter bar, and a cutter shank;
the drill bit, the cutter bar and the cutter handle are integrally made of conductive materials; the cutter bar comprises a first rod section and a second rod section along the axial direction of the cutter bar, the radial section diameter of the first rod section is not smaller than that of the drill bit, and the axial height of the first rod section is smaller than the distance from the third conducting layer to the back drilling surface; the surfaces of the drill bit and the second rod section are respectively plated with insulating films;
wherein the drill bit and the insulating film plated on the surface of the drill bit form the first external insulation part; the first pole section is formed into the outer conductive part, and the outer conductive part is connected with the intermediate electric connection unit through the second pole section and the handle; the second rod section and the insulating film plated on the surface of the second rod section form the second external insulation part.
Optionally, the composite drill specifically includes: a drill bit, a cutter bar, and a cutter shank;
the cutter bar comprises a first rod section and a second rod section along the axial direction of the cutter bar, the radial section diameter of the first rod section is not smaller than that of the drill bit, and the axial height of the first rod section is smaller than the distance from the third conducting layer to the back drilling surface;
the drill bit is made of a non-conductive material; the first pole segment is made of an electrically conductive material; the second rod section is made of a non-conductive material, an inner cavity is formed in the second rod section along the axial direction of the second rod section, a conductive medium is filled in the inner cavity, and two ends of the conductive medium are respectively and electrically connected with the first rod section and the cutter handle;
wherein the drill bit is formed as a first outer insulating portion; the first rod section is formed into the outer conductive part, and the outer conductive part is connected with the intermediate electric connection unit through the conductive medium and the cutter handle; the second rod section and the insulating film plated on the surface of the second rod section form the second external insulation part.
Optionally, the drill bit is of a conical structure as a whole, or the drill bit comprises a tip part of a conical structure and a connecting column of a cylindrical structure.
Optionally, the intermediate electrical connection unit is specifically a drilling machine for controlling the movement of the composite drill.
Optionally, the manufacturing method of the multilayer board includes:
before lamination and pressing, paving a conductive material such as copper or conductive adhesive in a local area on the back drilling through layer in advance, wherein the local area covers and exceeds a projection area of a back drilling hole to be manufactured based on the first metalized through hole;
and (3) laminating the laminated plates to obtain a laminated plate, drilling holes on the laminated plate and metalizing the laminated plate to prepare the first metalized through hole and the second metalized through hole.
Optionally, the method further includes: and after the composite drill cutter is controlled to stop back drilling, manufacturing an outer layer graph of the multilayer board.
Optionally, the third conductive layer is made of copper or conductive adhesive.
Compared with the prior art, the invention has the beneficial effects that:
according to the embodiment of the invention, the third conducting layer is arranged in any back drill penetration layer in advance, the specially-made composite drill is combined to form the switch control loop consisting of the composite drill, the third conducting layer and the like, and the state of the switch control loop can be switched in the back drilling process of the composite drill, so that the back drill can be accurately controlled by controlling the back drill to stop when the specific switching situation of the state of the switch control loop is identified, the adverse effect caused by plate thickness difference is reduced, and the drilling depth control precision is effectively improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a back drilling method according to an embodiment of the present invention.
Fig. 2 is a schematic view of a multilayer board provided by an embodiment of the present invention before backdrilling.
FIG. 3 is a schematic diagram illustrating a state of the composite drill insert with copper on the outer conductive contact surface according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a state where an outer conductive portion of the composite drill bit completely passes through the back drilling surface and does not reach the third conductive layer according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a state where an outer conductive portion of the composite drill contacts a third conductive layer according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a first composite drill bit according to an embodiment of the present invention;
FIG. 7 is a schematic structural view of a second composite drill according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a third composite drill according to an embodiment of the present invention.
Description of the drawings:
multilayer board 1: a first metalized via 11, a first conductive layer 12, a second metalized via 13, a second conductive layer 14, a third conductive layer 15;
the composite drill 2: the tool comprises a first outer insulating part 21, an outer conductive part 22, a second outer insulating part 23, a drill 24, a tool bar 25, a tool shank 26, a first bar section 27, a second bar section 28, an insulating film 29 and a conductive medium 30.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to solve the problem that the actual drilling depth and the theoretical drilling depth have larger deviation due to the plate thickness difference, the embodiment of the invention provides a back drilling manufacturing method, please refer to fig. 1, which comprises the following steps:
For convenience of description, the wall copper layer of the first metalized via 11 is referred to as a first conductive layer 12, and the wall copper layer of the second metalized via 13 is referred to as a second conductive layer 14. The first metallized via 11 will be used to make the desired signal transmission hole connecting the inner and outer lines, for which purpose it will be subsequently back-drilled. And the second metallized through hole 13 is used for manufacturing a switch control loop, and the switch control loop is used for controlling the starting and stopping of the back drilling movement.
In general, the multilayer board 1 can be divided into several back-drilled through layers and several back-drilled non-drilled through layers according to the desired back-drilling effect. A third conductive layer 15, which can be located on any of the back-drilled layers of the multilayer board 1, is formed on the outer periphery of the first metalized via 11 for electrically connecting the first conductive layer 12 of the first metalized via 11 and the second conductive layer 14 of the second metalized via 13.
On the back-drilled side of the multilayer board 1, the first conductive layer 12 on the inner wall of the first metalized through hole 11 and the second conductive layer 14 on the inner wall of the second metalized through hole 13 are connected through surface copper.
The second conductive layer 14 is also electrically connected to an intermediate electrical connection unit located outside the multilayer board 1. The intermediate electrical connection unit, which mainly plays a role of electrical connection, will also serve as a node of the switch control loop. The specific type of the intermediate electrical connection unit is not limited, and the intermediate electrical connection unit may be a drilling machine, or may be a specially-arranged connection wire, as long as two nodes adjacent to the intermediate electrical connection unit can be connected.
Illustratively, the specific manufacturing method of the multilayer board 1 specifically includes:
before lamination and lamination, paving a conductive material such as copper or conductive adhesive on a local area on the selected back drilling through layer in advance to form a third conductive layer 15, wherein the local area covers and exceeds a back drilling hole projection area to be manufactured based on the first metalized through hole 11;
the laminate is then pressed and then drilled and metallized to form a first metallized via 11 and a second metallized via 13.
At this time, since the surface copper (e.g., the copper clad layer on the surface of the outer core or the copper foil on the outer layer) on the back drilling surface of the multilayer board 1 is not treated, the surface copper covers the entire back drilling surface, so that the first conductive layer 12 of the first metalized through hole 11 and the second conductive layer 14 of the second metalized through hole 13 can be electrically connected through the surface copper.
In addition, when the multilayer board 1 only includes one single board, the second metallized through hole 13 needs to be opened in an idle area of the multilayer board 1 to avoid interference with the outer layer pattern or the inner layer pattern. When the multilayer plate 1 comprises a single plate and a tool edge, it is preferred that the second metallized through holes 13 are opened in the area of the tool edge to completely avoid occupying the limited space of the single plate.
And 102, controlling the composite drill 2 to perform back drilling at the position of the first metalized through hole 11.
Unlike the conventional drill made of conductive material, which has only conductive performance as a whole, the present embodiment employs a specially-made composite drill 2 having both conductive and insulating performances, which specifically includes: a first outer insulating part 21 at the cutting tip, an outer conductive part 22 at the cutting tip, and a second outer insulating part 23 at least the outer surface of which is insulated, which are integrally connected. That is, the first outer insulating portion 21, the outer conductive portion 22, and the second outer insulating portion 23 are sequentially disposed in the back drilling direction.
The first outer insulating portion 21 has an insulating function at least on the outer surface thereof. During the back drilling along the first metallized via 11, the first outer insulating portion 21 can always be in insulating connection with the first conductive layer 12.
An outer conductive part 22 having a conductive function at least on an outer surface thereof; the diameter of the radial section of the outer conductive part 22 is not less than the diameter of the radial section of the first outer insulating part 21, and the axial height of the outer conductive part 22 is less than the distance from the third conductive layer 15 to the back drilling surface. Based on this, in the back drilling process, the outer conductive part 22 will gradually descend along the back drilling hole, and first electrically connect with the exposed surface copper of the back drilling hole, then electrically connect with the exposed substrate of the middle part of the back drilling hole, and then electrically connect with the exposed third conductive layer 15 of the back drilling hole.
At the same time, the outer conductive part 22 is also electrically connected to the intermediate electrical connection unit. The outer conductive part 22 of the composite drill bit 2, the third conductive layer 15 located on the back drilling penetration layer, the second conductive layer 14 located on the inner wall of the second metalized through hole 13, the intermediate electrical connection unit, and the outer conductive part 22 of the composite drill bit 2 are sequentially connected to form the switch control loop of the present embodiment.
It is noted that throughout the backdrilling process, all adjacent link nodes in the remaining link portions of the switch control loop remain electrically connected, except for the link portion between outer conductive portion 22 and third conductive layer 15.
And 103, detecting the state of a switch control loop after the composite drill bit starts to contact the back drilling surface in real time in the back drilling process, and controlling the composite drill bit 2 to stop back drilling when detecting that the switch control loop sequentially forms state switching of a first open circuit state, a first short circuit state, a second open circuit state and a second short circuit state.
In the back drilling process, the composite drill bit 2 gradually descends along the axial direction of the first metalized through hole 11, the first outer insulating part 21 positioned at the front end of cutting gradually cuts and removes the contacted first conductive layer 12, and a back drilling hole with the aperture larger than that of the first metalized through hole 11 is formed.
For convenience of description, in the following section, a timing at which the first outer insulating portion 21 of the composite drill bit 2 starts to contact the back-drilled surface of the multilayer board 1 is referred to as a first timing in terms of back-drilling timing; the time when the outer conductive portion 22 starts to contact the back-drilled surface of the multilayer board 1 is referred to as a second time; the time when the outer conductive part 22 completely passes through the back-drilled surface of the multilayer board 1 is referred to as a third time; the timing when the outer conductive portion 22 starts to contact the third conductive layer 15 is referred to as a fourth timing; the timing when the outer conductive portion 22 completely passes through the third conductive layer 15 is referred to as a fifth timing.
It can be understood that, in the back drilling stage between the first time (including the first time) and the second time (not including the second time), the first external insulating portion 21 is in contact insulated connection with the surface copper, and the external conductive portion 22 is still located above the back drilling surface, and is not in contact conductive connection with the surface copper of the back drilling surface, so that the external conductive portion 22 cannot be electrically connected with the third conductive layer 15, and thus the switch control loop formed by sequentially connecting the external conductive portion 22, the third conductive layer 15, the second conductive layer 14, the intermediate electrical connection unit, and the external conductive portion 22 exhibits the first open state.
In the back drilling stage between the second time and the third time (excluding the third time), as shown in fig. 3, the outer conductive portion 22 is in contact conductive connection with the surface copper of the back drilling surface, and since the surface copper is electrically connected to the second conductive layer 14 and the second conductive layer 14 is electrically connected to the third conductive layer 15, the outer conductive portion 22 is indirectly electrically connected to the third conductive layer 15 in the back drilling stage, so that the switch control circuit is in a first short circuit state.
In the back drilling stage between the third time and the fourth time (excluding the fourth time), as shown in fig. 4, the outer conductive part 22 is located between the back drilling surface and the third conductive layer 15, and cannot contact with the surface copper of the back drilling surface or the exposed portion of the back drilling hole wall of the third conductive layer 15, so that the outer conductive part 22 cannot be electrically connected to the third conductive layer 15, and the switch control circuit is in the second open state.
In the back drilling stage between the fourth time and the fifth time (excluding the fifth time), as shown in fig. 5, the outer conductive part 22 and the third conductive layer 15 are in contact conductive connection with the exposed portion of the hole wall of the back drilling hole, so that the outer conductive part 22 and the third conductive layer 15 are directly electrically connected, and the switch control circuit is in a second short circuit state.
Therefore, in the whole back drilling stage taking the first moment as the initial moment, the switch control loop can form state switching of a first open circuit state, a first short circuit state, a second open circuit state and a second short circuit state in sequence according to the back drilling time sequence.
Based on this, when the recognition switch control circuit forms the state switching of the first open circuit state, the first short circuit state, the second open circuit state and the second short circuit state in sequence, the control instruction for stopping the back drilling is generated, the actual drilling depth which is basically consistent with or particularly close to the theoretical drilling depth can be obtained, and the control precision of the back drilling depth is effectively improved.
Illustratively, the third conductive layer 15 is located on the back-drilled through layer of the multilayer board 1 adjacent to the back-drilled non-through layer. In this case, the step of controlling the composite drill 2 to stop the back drilling specifically includes: the composite drill bit 2 is controlled to stop moving immediately or stop moving in a delayed way.
Meanwhile, since the first outer insulating portion 21 of the composite drill bit 2 has a certain height and may have a sharp cutting angle, and the third conductive layer 15 has a certain thickness, when the switching control loop is switched to the second short-circuit state, there are two cases: in the first case, the first outer insulating portion 21 has completely drilled through the third conductive layer 15, and the back drilling can be controlled to stop immediately or to stop after a delay; in the second case, the first outer insulating portion 21 has not yet completely drilled through the third conductive layer 15, and it is necessary to control the delay to stop the backdrilling. In either case, to avoid that the backdrilling is too deep or too shallow, it needs to be ensured that after stopping the backdrilling motion, the third conductive layer 15 has been completely drilled off and the first outer insulation portion 21 has not been drilled to the backdrilling non-drilled-through layer. In practical application, the optimal stop control mode, the better delay time and the composite drill 2 with reasonable size can be selected through a plurality of tests according to the test comparison result; the required delay time can also be estimated according to the actual size of the composite drill bit 2, the thickness of the third conductive layer 15, the back drilling speed and other parameters in the actual environment, and the invention is not limited.
Obviously, in this example, because the third conducting layer 15 is located the back drilling penetration layer of the bottommost layer, the back drilling is stopped immediately or with a delay in this embodiment when the recognition switch control loop forms the second short circuit, and it can be effectively ensured that the composite drill bit 2 can not only completely drill the back drilling penetration layer of the bottommost layer, but also can not drill the back drilling non-drilling penetration layer adjacent to the back drilling penetration layer, so that the obtained actual drilling depth is substantially consistent with the theoretical drilling depth, the adverse effect of the plate thickness difference phenomenon is completely eradicated, and the drilling depth control precision is greatly improved.
As yet another example, third conductive layer 15 is located on any of the back-drilled through layers of multilayer board 1 that are not adjacent to the back-drilled non-through layer. In this case, the step of controlling the composite drill 2 to stop the back drilling specifically includes: and controlling the composite drill bit 2 to stop moving in a delayed way.
In the same way, to avoid that the backdrilling is too deep (e.g. drilling to the backdrilling non-drilled layer immediately adjacent to the backdrilling drilled layer) or that the backdrilling is too shallow (e.g. not drilling to the backdrilling drilled layer immediately adjacent to the backdrilling non-drilled layer), it is necessary to ensure that: after stopping the back drilling movement, the end of the first outer insulation portion 21 is located between the adjacent back drilled and back drilled non-drilled layers. In practical application, the composite drill 2 with better delay time and reasonable size can be selected through multiple tests according to test comparison results; the required delay time can also be estimated according to the actual size of the composite drill bit 2, the thickness of the third conductive layer 15, the back drilling speed and other parameters in the actual environment, and the invention is not limited.
Unlike the previous example, the third conductive layer 15 is provided on the non-bottommost back-drill penetration layer, that is, when it is detected that the back drill reaches a slightly shallow position (the theoretical drilling depth is not reached), the composite drill 2 is controlled to continue back drilling for a preset time and then is stopped. Compared with the prior art, the drilling depth control accuracy can be improved to a certain extent by the aid of the method.
In the present embodiment, the composite drill bit 2 includes the first outer insulating portion 21, the outer conductive portion 22, and the second outer insulating portion 23, and the structural implementation thereof may be various.
The first composite drill 2, as shown in fig. 6, specifically includes: a drill bit 24, a tool shank 25, and a tool shank 26; the drill bit 24, the tool shank 25 and the tool shank 26 are integrally made of an electrically conductive material.
The tool shank 25, in its axial direction, comprises a first shank segment 27 and a second shank segment 28. Wherein the radial cross-sectional diameter of the first segment 27 is no less than the radial cross-sectional diameter of the drill bit 24 to ensure that the first segment 27 can be contacted by the face copper of the backdrilling hole or the exposed portion of the third conductive layer 15 at the wall of the backdrilling hole when the backdrilling is in place. At the same time, the axial height of the first rod section 27 is smaller than the distance of the third conductive layer 15 to the back drilling surface.
The surfaces of the drill bit 24 and the second shaft section 28 are each coated with an insulating film 29.
The drill 24 and the insulating film 29 plated on the surface thereof form a first external insulating portion 21; the first rod section 27 is formed as the outer conductive portion 22, and the outer conductive portion 22 can electrically connect the inter-electric connection unit through the second rod section 28 and the holder 26; the second rod section 28 is formed with an insulating film 29 plated on its surface as a second outer insulating portion 23.
It is understood that the drill head 24 may be of a generally conical configuration, or that the drill head 24 may include a tip of a conical configuration and a connecting post of a cylindrical configuration (as shown in fig. 5), although the invention is not limited in particular.
The second composite drill 2, as shown in fig. 7, specifically includes: a drill bit 24, a tool shank 25, and a tool shank 26.
The tool shank 25, in its axial direction, comprises a first shank segment 27 and a second shank segment 28. Wherein the radial cross-sectional diameter of the first rod section 27 is not less than the radial cross-sectional diameter of the drill bit 24, and the axial height of the first rod section 27 is less than the distance from the third conductive layer 15 to the back drilling surface.
The drill bit 24 is made of a non-conductive material; the first shaft section 27 of the tool shaft 25 is made of an electrically conductive material; the second rod section 28 of the tool bar 25 is made of a non-conductive material, and the second rod section 28 forms an inner cavity along the axial direction thereof, the inner cavity is filled with a conductive medium 30, and two ends of the conductive medium 30 are respectively electrically connected with the first rod section 27 and the tool shank 26.
At this time, the drill 24 is formed as the first outer insulating portion 21; the first bar segment 27 is formed as an outer conductive portion 22, and the outer conductive portion 22 can electrically connect the intermediate electrical connection unit with the holder 26 via the conductive medium 30; a second pole segment 28 formed as a second outer insulation 23.
As shown in fig. 8, the third composite drill 2 specifically includes: a drill bit 24, a tool shank 25, and a tool shank 26; the drill bit 24, the tool shank 25 and the tool shank 26 are integrally made of an electrically conductive material.
The tool shank 25, in its axial direction, comprises a first shank segment 27 and a second shank segment 28. Wherein the radial cross-sectional diameter of the first rod section 27 is not less than the radial cross-sectional diameter of the drill bit 24, and the axial height of the first rod section 27 is less than the distance from the third conductive layer 15 to the back drilling surface.
The drill 24 is made of a non-conductive material, formed as a first outer insulation 21; the cutter bar 25 and the cutter shank 26 are integrally made of a conductive material, and the surface of the second bar section 28 is plated with an insulating film 29, so that the first bar section 27 is formed as an outer conductive portion 22, and the outer conductive portion 22 can be electrically connected to an intermediate electrical connection unit through the second bar section 28 and the cutter shank 26; the second rod section 28 is formed with an insulating film 29 plated on its surface as a second outer insulating portion 23.
In addition to the above-described structure types, the composite drill 2 of the present embodiment may also adopt other specific structures as long as the first outer insulating portion 21, the outer conductive portion 22, and the second outer insulating portion 23 capable of having the above-described functions.
In the actual production process, other conventional processes such as outer layer pattern making, surface treatment and the like need to be completed for the multilayer board 1. It should be noted that, preferably, the outer layer pattern forming step may be performed after the back drilling process is performed on the multilayer board 1 in this embodiment, so that the back drilling process does not need to perform any etching process on the surface copper of the back drilling surface, and the surface copper is remained to communicate the first conductive layer 12 and the second conductive layer 14, thereby improving the production efficiency.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A back drilling manufacturing method is characterized by comprising the following steps:
providing a multilayer board; the multilayer sheet includes: the hole wall is provided with a first metalized through hole of a first conductive layer, a second metalized through hole of a second conductive layer and a third conductive layer; on the back drilling surface of the multilayer board, the first conducting layer is electrically connected with the second conducting layer through surface copper;
the third conducting layer is positioned on one back drilling penetrating layer of the multilayer board and is formed on the periphery of the first metalized through hole; the third conductive layer is electrically connected with the first conductive layer and the second conductive layer respectively; the second conducting layer is also electrically connected with a middle electric connection unit positioned outside the multilayer board;
controlling a composite drill to perform back drilling at the position of the first metalized through hole;
wherein the composite drill bit comprises: the cutting tool comprises a first outer insulation part, an outer conductive part and a second outer insulation part, wherein the first outer insulation part is positioned at the front end of cutting and at least provided with an insulated outer surface, the outer conductive part is positioned at the middle end of cutting and at least provided with an insulated outer surface, the second outer insulation part is positioned at the rear end of cutting and at least provided with an insulated outer surface, the diameter of the radial section of the outer conductive part is not smaller than that of the first outer insulation part, and the axial height of the outer conductive part is smaller than the distance from the third conductive layer to the back drilling surface; the outer conductive part is electrically connected with the intermediate electric connection unit; the outer conductive part, the third conductive layer, the second conductive layer, the intermediate electrical connection unit and the outer conductive part are sequentially connected to form a switch control loop;
in the back drilling process, detecting the state of the switch control loop in real time after the composite drill bit starts to contact a back drilling surface; and when detecting that the switch control loop forms the state switching of a first open circuit state, a first short circuit state, a second open circuit state and a second short circuit state in sequence, controlling the composite drill cutter to stop back drilling.
2. The backdrill fabrication method of claim 1, wherein the third conductive layer is located on a backdrill through layer of the multiwall sheet adjacent to a backdrill non-through layer;
the controlling the composite drill bit to stop back drilling comprises: and controlling the composite drill to stop moving immediately or stop moving in a delayed manner.
3. The backdrill manufacturing method of claim 1, wherein the third conductive layer is located on any backdrill through layer of the multilayer board that is not adjacent to a backdrill non-through layer;
the controlling the composite drill bit to stop back drilling comprises: and controlling the composite drill cutter to stop moving in a delayed manner.
4. The back drill manufacturing method according to claim 1, wherein the composite drill specifically comprises: a drill bit, a cutter bar, and a cutter shank;
the drill bit, the cutter bar and the cutter handle are integrally made of conductive materials; the cutter bar comprises a first rod section and a second rod section along the axial direction of the cutter bar, the radial section diameter of the first rod section is not smaller than that of the drill bit, and the axial height of the first rod section is smaller than the distance from the third conducting layer to the back drilling surface; the surfaces of the drill bit and the second rod section are respectively plated with insulating films;
wherein the drill bit and the insulating film plated on the surface of the drill bit form the first external insulation part; the first pole section is formed into the outer conductive part, and the outer conductive part is connected with the intermediate electric connection unit through the second pole section and the handle; the second rod section and the insulating film plated on the surface of the second rod section form the second external insulation part.
5. The back drill manufacturing method according to claim 1, wherein the composite drill specifically comprises: a drill bit, a cutter bar, and a cutter shank;
the cutter bar comprises a first rod section and a second rod section along the axial direction of the cutter bar, the radial section diameter of the first rod section is not smaller than that of the drill bit, and the axial height of the first rod section is smaller than the distance from the third conducting layer to the back drilling surface;
the drill bit is made of a non-conductive material; the first pole segment is made of an electrically conductive material; the second rod section is made of a non-conductive material, an inner cavity is formed in the second rod section along the axial direction of the second rod section, a conductive medium is filled in the inner cavity, and two ends of the conductive medium are respectively and electrically connected with the first rod section and the cutter handle;
wherein the drill bit is formed as a first outer insulating portion; the first rod section is formed into the outer conductive part, and the outer conductive part is connected with the intermediate electric connection unit through the conductive medium and the cutter handle; the second rod section and the insulating film plated on the surface of the second rod section form the second external insulation part.
6. The back drill manufacturing method according to claim 4 or 5, wherein the drill bit is integrally in a conical structure, or comprises a tip part in a conical structure and a connecting column in a cylindrical structure.
7. Back-drill production method according to claim 1, characterized in that the intermediate electrical connection unit, in particular a drilling machine for controlling the movement of the composite drill.
8. The back-drill manufacturing method of claim 1, wherein the manufacturing method of the multilayer board comprises:
before lamination and pressing, laying the third conducting layer in advance in a local area on the back drilling through layer, wherein the local area covers and exceeds a projection area of a back drilling hole to be manufactured based on the first metalized through hole;
and (3) laminating the laminated plates to obtain a laminated plate, drilling holes on the laminated plate and metalizing the laminated plate to prepare the first metalized through hole and the second metalized through hole.
9. The back-drill making method according to claim 1, further comprising: and after the composite drill cutter is controlled to stop back drilling, manufacturing an outer layer graph of the multilayer board.
10. The back-drilling manufacturing method according to claim 1, wherein the third conductive layer is made of copper or conductive adhesive.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010762656.2A CN113286429B (en) | 2020-07-31 | 2020-07-31 | Back drill manufacturing method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010762656.2A CN113286429B (en) | 2020-07-31 | 2020-07-31 | Back drill manufacturing method |
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| CN113286429A true CN113286429A (en) | 2021-08-20 |
| CN113286429B CN113286429B (en) | 2022-12-30 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI785820B (en) * | 2021-09-29 | 2022-12-01 | 欣興電子股份有限公司 | Method and drill for removing partial metal wall of hole |
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| CN1787726A (en) * | 2005-11-22 | 2006-06-14 | 沪士电子股份有限公司 | Method for drilling deep hole and PCB product obtained by same method |
| US20080314625A1 (en) * | 2007-06-22 | 2008-12-25 | Hitachi Via Mechanics, Ltd. | Printed Circuit Board and Method of Manufacturing the Same |
| CN104582288A (en) * | 2015-01-14 | 2015-04-29 | 景旺电子科技(龙川)有限公司 | PCB back drilling plate back drilling depth detecting method |
| CN208930432U (en) * | 2018-08-15 | 2019-06-04 | 深南电路股份有限公司 | Drilling machine |
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|---|---|---|---|---|
| CN1787726A (en) * | 2005-11-22 | 2006-06-14 | 沪士电子股份有限公司 | Method for drilling deep hole and PCB product obtained by same method |
| US20080314625A1 (en) * | 2007-06-22 | 2008-12-25 | Hitachi Via Mechanics, Ltd. | Printed Circuit Board and Method of Manufacturing the Same |
| CN104582288A (en) * | 2015-01-14 | 2015-04-29 | 景旺电子科技(龙川)有限公司 | PCB back drilling plate back drilling depth detecting method |
| CN208930432U (en) * | 2018-08-15 | 2019-06-04 | 深南电路股份有限公司 | Drilling machine |
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| TWI785820B (en) * | 2021-09-29 | 2022-12-01 | 欣興電子股份有限公司 | Method and drill for removing partial metal wall of hole |
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| CN113286429B (en) | 2022-12-30 |
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