CN113079638A - Back drilling method and device for PCB - Google Patents
Back drilling method and device for PCB Download PDFInfo
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- CN113079638A CN113079638A CN202010005870.3A CN202010005870A CN113079638A CN 113079638 A CN113079638 A CN 113079638A CN 202010005870 A CN202010005870 A CN 202010005870A CN 113079638 A CN113079638 A CN 113079638A
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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
- H05K2203/16—Inspection; Monitoring; Aligning
- H05K2203/163—Monitoring a manufacturing process
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- Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
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Abstract
The application provides a back drilling method and back drilling equipment for a PCB. The method comprises the following steps: the machine station determines a drill stopping layer of the drill cutter in the PCB according to the position of a target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill cutter after the drill stopping and the length of the tool point of the drill cutter, wherein the target layer is a reaching layer of a through hole on the first surface of the PCB, and the first surface of the PCB is the opposite surface of a surface to be drilled of the PCB; the depth control sensor counts for one time when the handle of the drill cutter is contacted with the bonding pad, and sends the count value to the machine table; and when the drill cutter is determined to have drilled to the drilling stop layer according to the count value, the machine station controls the drill cutter to stop drilling. The method ensures that the back drill length is not influenced by the uneven thickness of the PCB, the warping and the like, and improves the back drill precision.
Description
Technical Field
The invention relates to the technical field of machinery, in particular to a back drilling method and back drilling equipment for a PCB (printed circuit board).
Background
The communications industry continues to grow at a high rate and the speed and frequency of digital signal transmission continues to increase, making signal transmission integrity issues increasingly acute. When the frequency of a circuit signal is increased to a certain height, redundant copper plating of a useless hole copper part in a via hole in the PCB is equivalent to that of an antenna, signal radiation is generated to interfere other surrounding signals, and the normal work of a circuit system is affected seriously, so that the redundant copper plating needs to be drilled away in a back drilling mode, and the integrity of the signal is improved.
In the prior art, the back drilling method is to measure the thickness of the PCB, calculate the drilling depth according to the thickness of the PCB, the length of the via hole and the back drilling depth redundancy, and control the operation of the drill according to the drilling depth. However, the PCB has the phenomena of uneven thickness and bending of the warped board due to the influence of the process, the temperature and the like, so that the thickness of the measured PCB is not accurate enough, and the back drilling precision is not high.
Disclosure of Invention
The application provides a back drilling method and back drilling equipment for a PCB, which are used for improving the back drilling precision.
On one hand, the application provides a back drilling method of a PCB, which is applied to back drilling equipment of the PCB and comprises a machine table, a drill cutter, a conductor and a depth control sensor, wherein the PCB can be placed on the upper surface of the machine table, the PCB is a multilayer board, each layer is provided with a bonding pad, the machine table is connected with the conductor, two ends of the depth control sensor are connected with the conductor and the drill cutter, the conductor is in contact arrangement with the PCB, and the angle of the tool point of the drill cutter is larger than a preset threshold value; the method comprises the following steps: the machine station determines a drill stopping layer of the drill cutter in the PCB according to the position of a target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill cutter after the drill stopping and the length of the tool point of the drill cutter, wherein the target layer is a reaching layer of a through hole on the first surface of the PCB, and the first surface of the PCB is the opposite surface of a surface to be drilled of the PCB; the depth control sensor counts for one time when the handle of the drill cutter is contacted with the bonding pad, and sends the count value to the machine table; and when the drill cutter is determined to have drilled to the drilling stop layer according to the count value, the machine station controls the drill cutter to stop drilling.
According to the method, the drill tool is controlled to work by determining the drill stopping layer of the drill tool in the PCB and acquiring the layer number of the layer where the welding pad is contacted with the handle of the drill tool, and when the drill tool is determined to be drilled to the drill stopping layer according to the layer number, the machine controls the drill tool to stop drilling, so that the back drilling length is not influenced by the thickness unevenness, warping and the like of the PCB, and the back drilling precision is improved.
Optionally, the determining, by the machine station, the drill stop layer of the drill in the PCB according to the position of the target layer in the PCB, the interlayer distance of the PCB, the inertial distance of the drill after the drill stops drilling, and the length of the tool tip of the drill includes: and the machine station determines a layer which is closest to the target layer and has a distance with the target layer greater than the sum of the inertia distance and the length of the tool nose of the drilling tool according to the position of the target layer in the PCB and the interlayer distance of the PCB, and determines the layer as a drill stopping layer. The drill stop layer can be determined by the method.
On the other hand, this application still provides a back drilling equipment of PCB, includes: the depth control device comprises a machine table, a drill, a conductor and a depth control sensor, wherein a PCB (printed Circuit Board) can be placed on the upper surface of the machine table, the PCB is a multilayer board, each layer of the PCB is provided with a bonding pad, the machine table is connected with the conductor, two ends of the depth control sensor are connected with the conductor and the drill, and the conductor is in contact with the PCB; the tool nose angle of the drill tool is larger than a preset threshold value; the machine station is used for determining a drill stopping layer of the drill in the PCB according to the position of a target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill after the drill stops drilling and the length of the tool point of the drill, wherein the target layer is a reaching layer of a through hole on the first surface of the PCB, and the first surface of the PCB is the opposite surface of a surface to be drilled of the PCB; the depth control sensor is used for counting once when the handle of the drill cutter is contacted with the bonding pad, and sending a counting value to the machine table; and the machine station is also used for controlling the drill cutter to stop drilling when the drill cutter is determined to have drilled to the drilling stop layer according to the counting value.
The machine station of the equipment can determine the drill stopping layer of the drill in the PCB according to the position of a target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill after the drill stops drilling and the length of the tool tip of the drill; the depth control sensor can count once when the drill tool shank contacts the bonding pad, and sends the count value to the machine table, so that the machine table can acquire the layer number of the layer where the bonding pad is located; and when the machine station determines that the drill cutter has drilled to the drilling stop layer according to the layer number, controlling the drill cutter to stop drilling. Therefore, the back drill length is not affected by the uneven thickness of the PCB, the warping and the like, and the back drill precision is improved.
Optionally, the back drilling device further comprises: the cover plate comprises a conductive surface, and the conductor is arranged in contact with the PCB through the conductive surface. Based on this, when the drill bit is drilled down, the apron can prevent that the drill bit from skidding, further improves the precision of back drilling.
Optionally, the conductive surface is a lower surface of the cover plate. Therefore, the gap between the cover plate and the PCB can be reduced, and the cover plate can be attached to the PCB more closely.
Optionally, the conductor comprises: the clamping portion is used for fixing the conductive portion between the cover plate and the PCB. Therefore, the cover plate, the conductive part and the PCB can be prevented from sliding, the precision of the back drill is improved, when the drill bit drills downwards, the drill bit can be prevented from slipping due to the sliding of the cover plate, the damage of the drill bit is reduced, and the precision of the back drill is further improved.
Optionally, the conductive surface is at least one side surface and a lower surface of the cover plate. Therefore, the side surface of the cover plate is contacted with the conductor, so that the bottom surface of the cover plate is tightly attached to the PCB.
Optionally, the conductor comprises: joint portion and conductive part, conductive part and conductive surface contact, joint portion is used for fixed cover plate. Therefore, the cover plate and the PCB can be prevented from sliding, the precision of the back drill is improved, when the drill bit drills downwards, the drill bit can be prevented from slipping due to the sliding of the cover plate, the damage of the drill bit is reduced, and the precision of the back drill is further improved.
Optionally, an insulating plate is disposed between the upper surface of the machine platform and the first surface of the PCB. On one hand, the PCB can be insulated from the machine table, and the safety of the back drilling device of the PCB is improved; on the other hand, the vibration absorption function can be realized when the drill bit drills downwards, the PCB is protected, and the reliability of back drilling is improved.
Optionally, the machine is specifically configured to: and determining a layer which is closest to the target layer and has a distance with the target layer greater than the sum of the inertia distance and the length of the tool nose of the drilling tool according to the position of the target layer in the PCB and the interlayer distance of the PCB, and determining the layer as a drill stopping layer. Therefore, the characteristic that the back drilling length is too long and the PCB is influenced can be prevented, and the via hole is prevented from being damaged due to too long inertia distance after the drill cutter stops drilling, too long tool nose length of the drill cutter and the like.
The back drilling method and the back drilling equipment of the PCB provided by the invention determine the drill stopping layer of the drill in the PCB according to the position of the target layer in the PCB, the interlayer spacing of the PCB, the inertial distance of the drill after stopping drilling and the length of the tool tip of the drill; when the drill cutter contacts the first bonding pad, acquiring the layer number of the layer where the first bonding pad is located; and if the drill cutter is determined to have drilled to the drill stopping layer according to the layer number, controlling the drill cutter to stop drilling, so that the back drill length is not influenced by the thickness unevenness, warping and the like of the PCB, and the back drill precision is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.
FIG. 1 is a schematic view of a copper plated through hole according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a backdrilled hole and a via hole provided in an embodiment of the present application;
fig. 3 is a flowchart of a method for backdrilling a PCB according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of a back drilling device for a PCB according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of a back drilling device for a PCB according to another embodiment of the present application;
fig. 6 is a schematic structural diagram of a back drilling device of a PCB with a cover plate according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of a back drilling device of a PCB with a cover plate according to another embodiment of the present application;
fig. 8 is a schematic structural diagram of a back drilling device of a PCB with a conductor including a clamping portion and a conductive portion according to an embodiment of the present application;
fig. 9 is a schematic structural diagram of a back drilling device for a PCB, in which an insulating plate is disposed between an upper surface of a machine and a first surface of the PCB, according to an embodiment of the present disclosure;
fig. 10 is a partially enlarged view of the drill bit and the PCB of the PCB back drilling apparatus provided in any one of the embodiments shown in fig. 4 to 9.
With the foregoing drawings in mind, certain embodiments of the disclosure have been shown and described in more detail below. These drawings and written description are not intended to limit the scope of the disclosed concepts in any way, but rather to illustrate the concepts of the disclosure to those skilled in the art by reference to specific embodiments.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.
Backdrilling is a special drilling technique to control the drilling depth in the fabrication of multilayer Printed Circuit Boards (PCBs). For example, a via hole from layer 1 to layer 3 is made in an 8-layer PCB, a via hole is usually drilled first, that is, a via hole is drilled from layer 1 to layer 8 of the PCB, and then a metal layer is formed by electroplating or depositing metal in the via hole, for example, copper plating or copper deposition, so that layer 1 to layer 8 of the PCB are connected sequentially through the metal layer in the via hole, fig. 1 is a schematic diagram of the via hole after copper plating provided in an embodiment of the present application, and layer 1 to layer 8 18 of the PCB are connected sequentially through the metal layer in the via hole 10. In practice, however, we only need layer 1 11 of the PCB to be connected to layer 3 13, without connecting layer 4 14 to layer 8 18. As shown in fig. 1, there are no signal lines connected to the PCB at the layer 4 and layer 8 vias 14 and 18, and thus are commonly referred to as copper-plated STUBs (STUBs). In high frequency high speed circuit designs, STUB can cause reflections, scattering, delays, etc. in signal transmission, affecting signal integrity. It is therefore necessary to drill away STUB from the back of the PCB, a process commonly referred to as back drilling. Fig. 2 is a schematic diagram of a back-drilled hole and a via hole provided in an embodiment of the present application, in which copper clad is drilled in a via hole from layer 8 to layer 4 14 of a PCB, and a via hole 22 and a back-drilled hole 21 having a larger diameter than the via hole are formed.
The existing back drilling method is to obtain the thickness of the PCB by measurement, calculate the drilling depth according to the thickness of the PCB, the length of a via hole and the back drilling depth redundancy, and control the operation of a drill according to the drilling depth. However, the PCB has the phenomena of uneven thickness and warping due to the influence of process, temperature, etc., and the measured thickness of the PCB and the actual thickness of the board at the drilling position have a deviation, resulting in low back drilling precision.
The main idea of the application is as follows: and determining a drilling stop layer through the PCB layer spacing, the inertia distance of the drilling tool after the drilling tool stops drilling, the length of the via hole and the length of the tool tip of the drilling tool, and controlling the drilling tool to work according to the layer number of the layer where the welding pad is contacted by the tool shank of the drilling tool and the position relation of the drilling stop layer.
The technical solutions of the present invention are described below with reference to several specific embodiments, wherein the same or similar concepts may be mutually referred to and are not repeated herein.
Fig. 3 is a flowchart of a method for backdrilling a PCB according to an embodiment of the present application, which may be performed by a PCB backdrilling apparatus, as shown in fig. 3, and the method includes the following steps:
s301: and the machine station determines the drill stopping layer of the drill cutter in the PCB according to the position of the target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill cutter after the drill cutter stops drilling and the length of the tool tip of the drill cutter.
The PCB is a multilayer board, and each layer is provided with a bonding pad. The pads may be laid at the location where the back-drilled hole needs to be drilled through during the PCB design phase.
The target layer is a reach layer of the via hole on the first surface of the PCB. For example, a via is from the first surface of the PCB to the third layer of the PCB, and the layer that reaches the via is the third layer of the PCB.
The first surface of the PCB is an opposite surface of a surface to be drilled of the PCB.
The drill bit can not be completely stopped after running for a certain distance due to inertia after stopping drilling, so that the drill bit has an inertia distance after stopping drilling.
Determining an implementation mode of a drill stopping layer of the drill in the PCB according to the position of a target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill after the drill stops drilling and the length of the tip of the drill: and determining a layer which is closest to the target layer and has a distance with the target layer greater than the sum of the inertia distance of the drill cutter after the drill cutter stops drilling and the length of the tip of the drill cutter according to the position of the target layer in the PCB and the interlayer distance of the PCB, and determining the layer as a drill stopping layer. The method can prevent the PCB characteristics from being influenced by the overlong length of the backdrill STUB, and can prevent the via hole from being damaged due to the overlong inertia distance after the drill cutter stops drilling, the overlong length of the tool nose of the drill cutter and the like.
For example, as shown in fig. 2, a via hole from layer 1 to layer 3 is made in an 8-layer PCB, that is, the position of a target layer in the PCB is layer 3 13, assuming that the inertia distance of a drill after stopping drilling is n and the length of the tip of the drill is l, if the layer distance between layer 4 14 and layer 3 is greater than n + l, the back drilling equipment of the PCB determines layer 4 14 as a drilling stop layer; if the interlayer spacing between the 4 th layer 14 and the 3 rd layer 13 is less than or equal to n + l, the back drilling equipment of the PCB calculates whether the new interlayer spacing between the 5 th layer 15 and the 3 rd layer 13 is greater than n + l or not until the drilling stop layer which is closest to the target layer and is greater than n + l is determined.
S302: and the depth control sensor counts once when the handle of the drill cutter contacts the bonding pad, and sends the count value to the machine table.
The bonding pad can be a bonding pad arranged at a position needing back drilling of each layer of the PCB; and the bonding pads can be arranged at the positions of drilling holes required by each layer of the PCB.
S303: and when the machine station determines that the drill cutter has drilled to the drilling stop layer according to the count value, controlling the drill cutter to stop drilling.
And if the machine station determines that the drill cutter does not drill to the drilling stop layer according to the layer number of the layer where the welding disc is contacted by the drill cutter handle, the machine station controls the drill cutter to continue to drill.
This application is through confirming the layer number on the layer that stops boring the layer of drill cutter in PCB and the pad place that obtains the drill cutter handle of a knife and contact, and control drill cutter work, when confirming the drill cutter according to this layer number and having bored to the layer that stops boring, then board accuse drill cutter stops the drilling, makes back drilling length not receive the influence of PCB plate thickness inequality, wane etc. has improved the back drilling precision.
Fig. 4 is a schematic structural diagram of a back drilling device for a PCB according to an embodiment of the present application, as shown in fig. 4, including: a machine table 41, a drill 42, a conductor 43 and a depth control sensor 44.
The upper surface of the machine table 41 can be provided with a PCB45, the PCB45 is a multilayer board, and each layer is provided with a bonding pad; the machine 41 is connected with the conductor 43; two ends of the depth control sensor 44 are respectively connected with the conductor 43 and the drill 42; the conductor 43 and the PCB45 are disposed in contact; the drilling tool 42 comprises a tool shank 421 and a tool tip 422, the angle of the tool tip 422 is larger than a preset threshold value, the tool shank 421 is conductive, and the tool tip 422 is nonconductive. The preset threshold value can be set according to actual conditions, and the application is not limited.
The PCB is a multilayer board, and each layer is provided with a bonding pad. Optionally, the bonding pads may be disposed in the area of each layer of the PCB that needs to be back-drilled, or may be disposed in all the areas of the PCB that need to be drilled. The diameter of the pad is larger than the diameter of the back-drilled hole.
The machine 41 may be used to determine the drill stop layer of the drill 42 in the PCB45 based on the location of the target layer in the PCB45, the layer spacing of the PCB45, the inertial distance of the drill 42 after stopping drilling, and the length of the drill tip 422. The machine 41 may also be configured to obtain the number of drilling stop layers, for example, the machine obtains the number of drilling stop layers of the PCB input by the user through the input interface; or the number of the drilling stop layers of the PCB stored by the storage device is obtained. The method for determining the drill stop layer may refer to the above embodiments, and is not described herein. The target layer is the reach layer of vias on the first surface 452 of the PCB45, and the first surface 452 of the PCB45 is the opposite side of the to-be-drilled surface 451 of the PCB 45.
The base 41 is connected to the conductor 43, and is used to electrically charge the conductor 43. Two ends of the depth control sensor 44 are respectively connected with the conductor 43 and the drill 42, so that the conductor 43, the depth control sensor 44 and the drill 42 are conducted. The conductor 43 is arranged in contact with the PCB45 for providing an electrically conductive path between the PCB and the drill bit. As shown in fig. 4, the conductor 43 may be a planar conductor. Of course, the conductor 43 may also be a conductor of other shapes, such as: fig. 5 is a schematic structural diagram of a PCB back drilling device according to another embodiment of the present application, and as shown in fig. 5, the conductor 43 is an inverted L-shaped conductor. The conductors 43 serve to provide a conductive path between the PCB45 and the drill 42, on the one hand, and to secure the PCB45 against deflection of the PCB45 due to vibration or the like during backdrilling, on the other hand.
The depth control sensor 44 is used for counting once when the drill tool shank 421 contacts the pad, and sending the counted value to the machine table 41. Accordingly, the machine 41 is further configured to control the drill 42 to stop drilling when it is determined that the drill 42 has drilled to the drilling stop layer according to the count value.
Optionally, the back drilling device for PCB further comprises: the cover plate comprises a conductive surface, and the conductor is arranged in contact with the PCB through the conductive surface.
The conductive surface of the cover plate may be the bottom surface of the cover plate. Fig. 6 is a schematic structural diagram of a back drilling device of a PCB with a cover plate according to an embodiment of the present application, for example, fig. 6 is based on the embodiment shown in fig. 4, as shown in fig. 6, and further includes: and a cover plate 61. The cover plate 61 includes a conductive surface 611, and the conductive surface 611 is a bottom surface of the cover plate. The conductive surface 611 is disposed in contact with the conductor 43 and the PCB 45. The conductive surface 611 may be a metal surface, such as a copper surface. The top surface of the cover plate can be a resin surface, so that the drill can be prevented from slipping when the drill drills down, and the accuracy of back drilling is further improved.
The conductive surface of the cover plate may also be the bottom surface and at least one side surface of the cover plate. For example, fig. 7 is a schematic structural diagram of a back drilling device of a PCB with a cover board according to another embodiment of the present application, as shown in fig. 7, the conductive surfaces of the cover board 61 are a bottom surface 611a of the cover board and a side surface 611b of the cover board, the bottom surface 611a of the cover board is disposed in contact with the PCB45, and the side surface 611b of the cover board is disposed in contact with the conductor 43. The top surface of the cover plate can be a resin surface, so that the drill can be prevented from slipping when the drill drills down, and the accuracy of back drilling is further improved. The conductor 43 is in contact with the side 611b of the cover plate and the side of the PCB, so that the gap between the cover plate and the PCB is reduced, and the cover plate and the PCB can be attached more closely.
Optionally, the conductor of the back drilling device of the PCB comprises: the clamping portion is used for fixing the conductive portion on the cover plate. Fig. 8 is a schematic structural diagram of a back drilling device of a PCB with a conductor including a clamping portion and a conductive portion according to an embodiment of the present application, and exemplarily, fig. 8 is based on the embodiment shown in fig. 6, and as shown in fig. 8, the conductor 43 includes: a snap-in section 431 and a conductive section 432. The clamping portion 431 is used for fixing the cover plate, so that the cover plate and the PCB are prevented from sliding, and the accuracy of the back drill is improved. Furthermore, when the drill bit drills downwards, the drill bit can be prevented from slipping due to the sliding of the cover plate, the damage of the drill bit is reduced, and the accuracy of back drilling is further improved. The clamping portion 431 may be made of metal or non-metal, and may be square, semicircular, polygonal, etc., and the material and shape of the clamping portion 431 are not limited in this application.
Optionally, an insulating plate is disposed between the upper surface of the machine table of the back drilling device of the PCB and the first surface of the PCB. For example, fig. 9 is a schematic structural diagram of a back drilling device for a PCB, in which an insulating plate is disposed between an upper surface of a machine and a first surface of the PCB according to an embodiment of the present application, and for example, fig. 9 is based on the embodiment shown in fig. 8, and further includes an insulating plate 91. The insulation board 91 is arranged between the upper surface of the machine platform and the first surface of the PCB, and is used for insulating the PCB from the machine platform and improving the safety of the back drilling device of the PCB on the one hand; on the other hand, the vibration absorption function is realized when the drill bit drills down, the PCB is protected, and the reliability of back drilling is improved. For example, the insulating plate 91 is a square template, and the material and shape of the insulating plate 91 are not limited in this application.
Fig. 10 is a partial enlarged view of the drill and the PCB of the PCB back drilling device provided in any one of the embodiments shown in fig. 4 to 9, and as shown in fig. 10, the PCB is an 8-layer board, which is respectively a first layer 101, a second layer 102, a third layer 103, a fourth layer 104, a fifth layer 105, a 6 th layer 106, a seventh layer 107 and an eighth layer 108, and a pad 109 having a diameter larger than that of the drill is disposed at a position corresponding to a back drilling hole of a surface to be drilled. The pads 109 are shown in fig. 10 on the same surface of each layer of the PCB as the surface to be drilled, it being understood that the pads 109 may also be on the opposite surface of each layer of the PCB from the surface to be drilled. Fig. 10 also shows a plated through hole 1010 on a PCB, a hole to be drilled 1011 and a drill 42, wherein the drill 42 comprises a shank 421 and a tip 422.
The working principle of the embodiment is as follows: for the drilling tool 42 with electric charge and the tool shank 422 conducting, if the tool shank 422 contacts the welding pad 109, the tool shank 422, the welding pad 109, the drilled hole 1011, the through hole 1010, the conductor 43 and the depth control sensor 44 form a conducting loop, and the depth control sensor detects current, counts for one time and transmits a count value to a machine station; if shank 422 does not contact pad 59, shank 422, pad 109, tape drill 1011, via 1010, conductor 43, and depth control sensor 44 cannot form a conductive loop, and the depth control sensor cannot detect current because no count is made. And the machine station judges whether the drill bit drills to the drill stopping layer according to the received count value, and controls the drill cutter to stop drilling if the drill bit drills to the drill stopping layer.
The machine of the back drilling equipment for the PCB can determine the drill stopping layer of the drill in the PCB according to the position of the target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill after the drill stops drilling and the length of the tool tip of the drill; the depth control sensor can count once when the drill tool shank contacts the bonding pad, and sends the count value to the machine table, so that the machine table can acquire the layer number of the layer where the bonding pad is located; and when the machine station determines that the drill cutter has drilled to the drilling stop layer according to the layer number, controlling the drill cutter to stop drilling. Therefore, the back drill length is not affected by the uneven thickness of the PCB, the warping and the like, and the back drill precision is improved.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
It will be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.
Claims (10)
1. The back drilling method of the PCB is characterized in that the method is applied to back drilling equipment of the PCB, a machine table, a drill cutter, a conductor and a depth control sensor, the PCB can be placed on the upper surface of the machine table, the PCB is a multilayer board, each layer is provided with a bonding pad, the machine table is connected with the conductor, two ends of the depth control sensor are connected with the conductor and the drill cutter, the conductor is in contact arrangement with the PCB, and the angle of the cutter point of the drill cutter is larger than a preset threshold value; the method comprises the following steps:
the machine station determines a drilling stop layer of the drill cutter in the PCB according to the position of a target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill cutter after the drill cutter stops drilling and the length of the tool tip of the drill cutter, wherein the target layer is a reaching layer of a through hole on a first surface of the PCB, and the first surface of the PCB is the opposite surface of a surface to be drilled of the PCB;
the depth control sensor counts for one time when the drill tool shank contacts the bonding pad, and sends a count value to the machine table;
and when the drill cutter is determined to have drilled to the drilling stop layer according to the count value, the machine station controls the drill cutter to stop drilling.
2. The back drilling method of claim 1, wherein the machine determines the drill stop layer of the drill bit in the PCB according to the position of the target layer in the PCB, the interlayer distance of the PCB, the inertial distance of the drill bit after the drill bit stops drilling and the length of the tip of the drill bit, and comprises the following steps:
and the machine station determines a layer which is closest to the target layer and is more than the sum of the inertia distance and the length of the tool nose of the drilling tool according to the position of the target layer in the PCB and the interlayer distance of the PCB, and determines the layer as the drilling stopping layer.
3. A back drilling apparatus of a PCB, comprising: the depth control device comprises a machine table, a drill cutter, a conductor and a depth control sensor, wherein a Printed Circuit Board (PCB) can be placed on the upper surface of the machine table, the PCB is a multilayer board, each layer of the PCB is provided with a bonding pad, the machine table is connected with the conductor, two ends of the depth control sensor are connected with the conductor and the drill cutter, the conductor is in contact arrangement with the PCB, and the angle of a tool point of the drill cutter is larger than a preset threshold value;
the machine station is used for determining a drill stopping layer of the drill cutter in the PCB according to the position of a target layer in the PCB, the interlayer distance of the PCB, the inertia distance of the drill cutter after the drill cutter stops drilling and the length of the tool tip of the drill cutter, wherein the target layer is a reaching layer of a through hole on a first surface of the PCB, and the first surface of the PCB is the opposite surface of a surface to be drilled of the PCB;
the depth control sensor is used for counting once when the drill tool shank contacts the bonding pad and sending a counting value to the machine table;
and the machine station is also used for controlling the drill cutter to stop drilling when the drill cutter is determined to have drilled to the drilling stop layer according to the count value.
4. The backdrilling apparatus of claim 3, further comprising: the cover plate comprises a conductive surface, and the conductor is arranged in a contact mode with the PCB through the conductive surface.
5. The backdrilling apparatus of claim 4, wherein the conductive surface is a lower surface of the cover plate.
6. The backdrilling apparatus of claim 5, wherein the conductor comprises: the conductive part is in contact with the conductive surface, and the clamping part is used for fixing the conductive part between the cover plate and the PCB.
7. The backdrilling apparatus of claim 4, wherein the conductive surface is at least one of a side surface and a lower surface of the cover plate.
8. The backdrilling apparatus of claim 7, wherein the conductor comprises: the conductive part is in contact with the conductive surface, and the clamping part is used for fixing the cover plate.
9. The backdrilling apparatus of any one of claims 3 to 8, wherein an insulating plate is provided between the upper surface of the machine and the first surface of the PCB.
10. The back drilling equipment of any one of claims 3 to 8, wherein the machine is specifically configured to: and determining a layer which is closest to the target layer and has a distance with the target layer greater than the sum of the inertia distance and the length of the tool nose of the drilling tool according to the position of the target layer in the PCB and the interlayer distance of the PCB, and determining the layer as the drilling stop layer.
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| CN202010005870.3A CN113079638B (en) | 2020-01-03 | 2020-01-03 | Back drilling method and device for PCB |
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| CN202010005870.3A CN113079638B (en) | 2020-01-03 | 2020-01-03 | Back drilling method and device for PCB |
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Cited By (1)
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| CN117279196A (en) * | 2023-11-17 | 2023-12-22 | 深圳市大族数控科技股份有限公司 | Circuit board, circuit board drilling device and circuit board drilling method |
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