CN117677050A - Method for improving drilling precision - Google Patents
Method for improving drilling precision Download PDFInfo
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- CN117677050A CN117677050A CN202311628576.8A CN202311628576A CN117677050A CN 117677050 A CN117677050 A CN 117677050A CN 202311628576 A CN202311628576 A CN 202311628576A CN 117677050 A CN117677050 A CN 117677050A
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- 238000005553 drilling Methods 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 32
- 230000033001 locomotion Effects 0.000 claims description 5
- 238000003754 machining Methods 0.000 claims description 4
- 238000012545 processing Methods 0.000 abstract description 7
- 229910052782 aluminium Inorganic materials 0.000 description 14
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 14
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- 230000008054 signal transmission Effects 0.000 description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 8
- 229910052802 copper Inorganic materials 0.000 description 7
- 239000010949 copper Substances 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 238000013461 design Methods 0.000 description 6
- 238000011161 development Methods 0.000 description 6
- 230000006698 induction Effects 0.000 description 5
- 230000001976 improved effect Effects 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 3
- 238000004891 communication Methods 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012797 qualification Methods 0.000 description 2
- 230000008093 supporting effect Effects 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 235000001674 Agaricus brunnescens Nutrition 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
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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
- H05K3/00—Apparatus or processes for manufacturing printed circuits
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Drilling And Boring (AREA)
Abstract
The invention relates to a method for improving drilling precision, which comprises the following steps: s1: setting a first feedback system and a second feedback system with different heights to detect coordinate values of the drill point; s2: touching the drill point to a surface cover plate covered on the PCB, and recording a first initial coordinate value H0' by a first feedback system; s3: calculating a first difference delta H0 'between H0' and H0 according to a first target value H0 of the first feedback system; s4: the second feedback system records a second initial coordinate value H1 ', and calculates a second difference delta H1 ' between H1 ' and H1 according to a second target value H1 of the second feedback system; s5: and calculating a third difference value delta H between delta H0 'and delta H1', when delta H=delta H0 '-delta H1' <5um, taking the H0 'position as a back drilling starting point, controlling the depth value of the drill required for the drill to drill down, and when delta H=delta H0' -delta H1 '> 5um, taking the H1' position as the back drilling starting point, controlling the depth value of the drill required for the drill to drill down. The invention realizes that the drilling precision of the back of the PCB processed by the machine tool is controlled within +/-20 um, and belongs to the technical field of drilling processing of the PCB.
Description
Technical Field
The invention relates to the technical field of drilling processing of PCB boards, in particular to a method for improving drilling precision.
Background
With the development of electronic information technology, especially the infrastructure of 5G communication network, the method is widely applied to the unprecedented development of communication, high-end server, supercomputer, medical equipment, aerospace and military base station, with the improvement of integration level of integrated circuit and other elements and the increase of I/O number, the development of electronic assembly technology and the development of high-frequency and high-speed digitization of signal transmission, and the development of electronic equipment, the functions of the backboard gradually move to bearing function daughter board, signal transmission, signal processing, power transmission and other functions, the backboard technology mainly in the communication industry moves to higher multilayer, large-size and simultaneously has the development of high-frequency and high-density directions, the speed of digital operation is faster and faster, the signal frequency is higher and higher, and the high-power amplifier is applied, and the main factors influencing the signal integrity of the signal system have great influence on the signal integrity except the factors of design, board materials, connectors, transmission lines, chip packaging and the like.
The commonality of high-tech and high-value-added electronic products is that low power consumption, low electromagnetic radiation, high reliability, miniaturization, light weight and high speed of signal transmission are all pursued in design, the design of a PCB high-speed signal transmission line is a key factor, generally, a PCB is required to transmit signals at high speed, the design is required to reduce the interconnection length between devices, improve the network topology, optimize EMC ((Electromagnetic Compatibility electromagnetic compatibility), EMI (Electromagnetic Interference ) and signal layer requirements to be preferentially arranged on an inner layer, reduce the length of an unused copper column of an electroplated via hole, adopt small holes, small graph lines and the like, according to the design, one way is to reduce the length of a plated Kong Moyong copper column by arranging a high-layer HDI board (High Density Interconnector high-density interconnection) with through holes in a PCB board as buried holes and blind holes, and the second way is to reduce the length of a plated Kong Moyong copper column by matching a common multi-layer board.
In circuit board designs, there is often a signal line that receives signals from the first layer, and if the back plate is a layer, the holes from layer 2 to the metallized holes of layer n-10 are not beneficial, but the integrity of the signals can be affected during signal transmission due to the higher effects of capacitive and inductive reactance of the unwanted portions of the metallized holes. The signal before back drilling is transmitted to the welding surface while the signal is not transmitted through the component surface, the L2-L n-10 layers do not play any role in connection and transmission, the signal is turned back and resonated, scattering, reflection, delay and the like of the signal transmission are possibly easy to cause, signal distortion is brought, the signal after back drilling is transmitted only to the component surface and is not transmitted to the welding surface any more, the signal transmission quality is improved, the PCB performance is improved, the back drilling is to remove the through hole section with the through hole end not playing any role in connection so as to improve the signal transmission quality, and the influence relationship of the redundant copper columns of the through holes on the signal quality is shown in the table 1.
TABLE 1 influence relationship of excess copper pillars of vias on signal quality
The existing PCB back drilling processing generally adopts the following two methods: the first method is to adopt a set target value depth control drilling method, when a back drilling plate is processed, each time the numerical control drilling machine control system controls the drill point to be at the height of the lower limit value and the depth of the target signal layer, the starting point of drilling is recorded, the corresponding hole depth is drilled, as shown in fig. 7-8, the back drilling process is analyzed, and the main factors influencing the back drilling precision are the thickness error and the drill starting point error of the workpiece. If drilling to the M layer is required, the theoretical depth of the deepest borehole is between the m+1 layer and the m+2 layer. In general, in order to ensure the drilling precision, the drill point can set the service life, generally about 2000 holes are used, the drill point needs to be replaced, when the drill point reaches the service life and another drill point is replaced, or when one plate is processed, another plate is replaced, the length errors of two drill points and the errors of two plates are affected, the precision of the depth control drill is affected, if all the 2 errors are introduced, the precision of the depth control drill is seriously out of tolerance, and the depth control drill requirement cannot be met.
The other method is to carry out back drilling on the PCB by adopting a high-frequency electronic induction principle, realize back drilling processing on the PCB numerical control mechanical drilling machine, take an air floatation main shaft on the PCB numerical control mechanical drilling machine as a signal channel, take the air floatation main shaft as a capacitor, take compressed air as an insulating medium, and take a rotor and a stator as two poles of the capacitor. The aluminum sheet is grounded through the mushroom head, the control board generates alternating current signals through the air floatation main shaft, a loop is formed when the air floatation main shaft clamps the cutter to touch the aluminum sheet covered on the PCB, and the cutter leaves the aluminum sheet to break the signals. When the signal loop forms, the position recorded by the grating ruler reading head in the Z-axis direction is the back drilling starting point position, and accurate depth control drilling is performed by means of the Z-axis grating ruler to finish back drilling, as shown in fig. 9. But the depth control precision is easily affected by the resistance of the drill point, the tolerance of dust on the tip of the drill point, copper wires and plate thickness, and the warping degree of the cover plate and the aluminum plate; meanwhile, long metal scraps brought by back drilling of the metalized holes are wound on the drill pins to cause the winding of the drill pins, when the drill pins do not touch the surface of the grounding aluminum sheet yet, the metal scraps wound on the drill pins touch the surface of the grounding aluminum sheet, and the loop is triggered in advance to cause early formation, so that the drilling depth is shallow finally.
The two methods are limited by the influence of a machine table surface and a multilayer PCB manufacturing process (copper foil, PP material thickness, flatness and warping), errors of the factors cannot be estimated, higher machining precision cannot be met when back drilling is machined, the errors are generally about +/-50 um, the errors cannot be controlled within +/-30 um, even through a plated through hole section of a signal layer required to be conducted leads to the PCB to report waste, or the remained plated through hole section is too long, the loss of a signal transmission process is increased, and the requirement of signal transmission among the multiple layers of the PCB is difficult to meet.
Disclosure of Invention
Aiming at the technical problems existing in the prior art, the invention aims at: the method for improving the drilling precision is used for controlling the drilling precision of the back of the PCB processed by the machine tool within +/-20 mu m, and solves the technical problems that the prior art cannot meet higher processing precision when the back drilling is processed, errors are generally about +/-50 mu m, and cannot be controlled within +/-30 mu m.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a method for improving drilling precision is used for machining back drilling of a PCB by a machine tool, and comprises the following steps:
s1: setting a first feedback system and a second feedback system which are positioned at different heights, wherein the first feedback system and the second feedback system are used for detecting coordinate values of the drill point;
s2: controlling a machine tool spindle to enable the drill point to touch a surface cover plate covered on the PCB, and recording a first initial coordinate value H0' of the drill point touching the surface cover plate by a first feedback system;
s3: according to the first target value H0 of the first feedback system set by the control system, calculating a first difference delta H0 'between the first initial coordinate value H0' and the first target value H0;
s4: the second feedback system records a second initial coordinate value H1 ' of the drill needle touching the surface cover plate, and calculates a second difference delta H1 ' between the second initial coordinate value H1 ' and the second target value H1 according to a second target value H1 of the second feedback system set by the control system;
s5: and calculating a third difference delta H between the first difference delta H0 ' and the second difference delta H1 ', wherein when delta H=delta H0 ' -delta H1 <5um, the control system takes the H0 ' position as a back drilling starting point, controls the depth value of the drill required by the drill point for drilling, and when delta H=delta H0 ' -delta H1 ' is more than 5um, the control system takes the H1 ' position as the back drilling starting point, and controls the depth value of the drill required by the drill point for drilling.
Preferably, in step S1, the first feedback system and the second feedback system are both disposed on a Z axis of the machine tool for drilling, and the first feedback system and the second feedback system detect a distance of movement of the Z axis to obtain coordinate values of the drill point.
Preferably, the first feedback system comprises a first grating tape, the first grating tape is assembled on the spindle clamp of the Z axis, a first reader of the first grating tape is electrically connected with the control system, and the first reader is used for reading the moving distance of the first grating tape along with the spindle clamp of the Z axis.
Preferably, the second feedback system comprises a second grating ruler belt, the second grating ruler belt is assembled on the chip suction cover of the Z shaft, a second reading head of the second grating ruler belt is electrically connected with the control system, and the second reading head is used for reading the moving distance of the second grating ruler belt along with the chip suction cover of the Z shaft.
Preferably, in step S2, the surface cover plate covered on the PCB board is grounded to make the surface cover plate have zero voltage, the drill needle is set to positive voltage, and an electric loop signal is formed when the drill needle contacts with the surface cover plate covered on the PCB board, and the electric loop signal triggers the control system to control the first feedback system and the second feedback system to record the coordinate values of the drill needle.
In general, the invention has the following advantages:
according to the method for improving the drilling precision, provided by the invention, the first feedback system and the second feedback system are arranged, and the deep drilling control mode adopting the high-frequency electronic induction principle is matched, so that the drilling point error of the back drilling is reduced, the back drilling precision of the PCB processed by a machine tool is controlled within +/-20 mu m, and the effects of improving the back drilling precision of the PCB, reducing the generation of bad back drilling plates and improving the drilling qualification rate of the back drilling plates are achieved.
Drawings
FIG. 1 is a flow chart of a method of improving drilling accuracy.
Fig. 2 is a side view of the first feedback system and the second feedback system disposed on a machine tool.
Fig. 3 is a perspective view of the first feedback system and the second feedback system disposed on a machine tool.
Fig. 4 is a front view of the first feedback system and the second feedback system disposed on a machine tool.
Fig. 5 is a schematic view of the drill point when back drilling a PCB board.
Fig. 6 is a schematic diagram of the prior art when back drilling is performed using the high frequency electronic induction principle.
Fig. 7 is a schematic view of a drilling stack.
Fig. 8 is a schematic structural view of the back plate.
Fig. 9 is a schematic diagram of a prior art back drilling process for a PCB board using a high frequency electronic induction principle.
Wherein, 1 is the timber apron, 2 is the lower bolster, 3 is the backplate, 4 is the surface cover plate, 5 is the pressure foot, 6 is the drill point, 7 is the chip suction cover, 8 is the Z axle, 9 is the second feedback system, 10 is first feedback system, 20 is the second readhead, 21 is the second fixing base, 22 is the second grating tape, 30 is first reading head, 31 is first fixing base, 32 is first grating tape.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments.
The method for processing the back drilling of the PCB by adopting the high-frequency electronic induction principle in the prior art comprises the following steps: an air floatation main shaft (Z axis) assembled on a PCB numerical control mechanical drilling machine is regarded as a capacitor, an alternating current signal is used as a signal channel through the air floatation main shaft, a loop is formed when an air floatation main shaft clamps a drill needle to touch a grounding aluminum sheet covered on a back drilling plate, the signal is broken when the air floatation main shaft leaves the grounding aluminum sheet covered on the back drilling plate, the signal loop forms an instantaneous vertical direction position, namely a back drilling starting point position, a control system records the current coordinate value of the drill needle, a feedback device in the vertical direction is used for drilling depth control, accurate depth control drilling is performed, the control system receives grating ruler reading head signals of all axes and CBTD plate signals to obtain a back drilling surface triggering position through a motion control unit, and after the back drilling surface triggering position is obtained, the Z axis is driven to perform depth drilling, so that back drilling is completed.
As shown in fig. 6, the PCB numerical control mechanical drilling machine includes a skid plate 1, a lower pad plate 2 and a Z-axis 8, which are disposed on a machine platform, a back plate 3 is clamped on the lower pad plate, the lower pad plate 2 is disposed on the skid plate, a surface cover plate 4,Z is covered on the back plate, the axis 8 moves on the machine platform of the PCB numerical control mechanical drilling machine along a vertical direction, a drill point 6, a chip suction cover 7 and a pressure pin 5 are clamped at one end (movable end) of the Z-axis, which faces the surface cover plate 4, and a first feedback system 10, that is, the above feedback device, is disposed at a fixed end of the Z-axis.
However, the depth control precision of the method is easily affected by the resistance of the drill point, the tolerance of dust on the tip of the drill point, copper wires and plate thickness, and the warping degree of the cover plate and the plate; meanwhile, the back drill is used for drilling a backboard made of metal materials, long metal scraps are brought in the drilling process, the metal scraps are wound on the drill needle to cause the drill needle to wind scraps, when the drill needle does not touch the surface of the grounding aluminum sheet yet, the metal scraps wound on the drill needle touch the surface of the grounding aluminum sheet, a loop is caused to form in advance, a current coordinate value of the drill needle is recorded by an advanced trigger control system, and finally the drilling depth is too shallow. In order to eliminate the adverse effect of static electricity, the chip suction cover is grounded, long metal chips brought in the drilling process and glass fiber dust can bypass the drill point and the grounded chip suction cover at the same time occasionally in the process of sucking away the inside of the chip suction cover, so that early triggering is caused to lead to shallow drilling; the completion of back drilling function lets alternating current signal pass through the air supporting main shaft, form the return circuit when air supporting main shaft centre gripping drill point runs into the earth aluminum sheet that covers on back drilling panel, the signal circuit break is then followed to the earth aluminum sheet that leaves to cover on back drilling panel, earth aluminum sheet is through metal connecting block ground connection, if metal connecting block ground connection is bad, then when the drill point contacted the aluminum sheet surface, the return circuit still did not form, control system defaults and has not found the surface and trigger the position yet, lead to boring deeply, these bad factors all can lead to the point error of getting into, can't satisfy back drilling's precision requirement.
With the prior drilling scheme, the back drilling depth tolerance is 99um, namely + -50 um, as shown in the following table
Compared with the prior art that the precision requirement of back drilling cannot be met due to the drilling point error caused by metal scraps, the embodiment aims to solve the problem of the prior art, and the method for improving the drilling precision is used for machining the PCB back drilling by a machine tool, and the machine tool is also a numerical control drilling machine.
As shown in fig. 1-5, the method comprises the steps of:
s1: setting a first feedback system and a second feedback system which are positioned at different heights, wherein the first feedback system and the second feedback system are used for detecting coordinate values of the drill point;
s2: controlling a machine tool spindle to enable the drill point to touch a surface cover plate covered on the PCB, and recording a first initial coordinate value H0' of the drill point touching the surface cover plate by a first feedback system;
s3: according to the first target value H0 of the first feedback system set by the control system, calculating a first difference delta H0 'between the first initial coordinate value H0' and the first target value H0;
s4: the second feedback system records a second initial coordinate value H1 ' of the drill needle touching the surface cover plate, and calculates a second difference delta H1 ' between the second initial coordinate value H1 ' and the second target value H1 according to a second target value H1 of the second feedback system set by the control system;
s5: and calculating a third difference delta H between the first difference delta H0 ' and the second difference delta H1 ', wherein when delta H=delta H0 ' -delta H1 <5um, the control system takes the H0 ' position as a back drilling starting point, controls the depth value of the drill required by the drill point for drilling, and when delta H=delta H0 ' -delta H1 ' is more than 5um, the control system takes the H1 ' position as the back drilling starting point, and controls the depth value of the drill required by the drill point for drilling.
By way of example only, and not by way of limitation,
in the method, by setting the first feedback system and the second feedback system with different heights, the control system sets a first target value H0 (Z) according to the position of the first feedback system relative to the surface cover plate, wherein Z represents the coordinate position of the first feedback system on the Z axis, the point where the drill needle contacts the surface cover plate is assumed to be an origin, namely H0 (Z1), on the X axis and the Y axis, and the second initial coordinate value H1 (Z2) of the second feedback system is similarly assumed to be Z1 to be 3, Z2 to be 5, namely H0 (3), and H1 (5), and the unit of the coordinate value is um.
Controlling a machine tool spindle to enable the drill point to touch a surface cover plate covered on the PCB, recording a first initial coordinate value H0 'of the drill point touching the surface cover plate (2) by a first feedback system, and recording a second initial coordinate value H1' of the drill point touching the surface cover plate by a second feedback system (11); the first difference Δh0 '=h0' -h0= -1um and the second difference Δh1 '=h1' -h1=6 um; the third difference Δh=Δh0 ' - Δh1 ' >5um, the first difference, the second difference and the third difference actually take absolute values, because the coordinate values are calculated, and the positive and negative of the coordinate values are only indicative of directions, so the third difference Δh= -1-6= -7 takes absolute values Δh=7 >5um, and therefore, the control system takes the H1 ' position as the back drilling starting point to control the depth value of the drill required for the drill to drill.
According to the example, if the drill bit has the drill point starting error caused by the metal chips, the difference value of the coordinate values detected by the first feedback system and the second feedback system and the preset coordinate value of the control system can be compared, so that whether the drill point starting error exists or not can be judged, the drill point can be adjusted, the drill point of the back of the PCB is machined within +/-20 microns, the drill point of the back of the PCB is improved, the production of bad back drill plates is reduced, and the qualification rate of the back drill plates is improved.
By adopting the scheme of the embodiment, the back drilling depth tolerance is 17um, namely + -8.5 um, the process requirements of + -20 um are met, as shown in the following table
In the above embodiment, the first feedback system and the second feedback system may be other structures capable of detecting coordinate values of the drill point, for example, by providing a sensor such as a displacement sensor, and detecting the position of the drill point relative to the surface cover plate, the coordinate values of the drill point may be obtained.
In step S1, the first feedback system and the second feedback system are both disposed on the Z axis of the machine tool for drilling, and the first feedback system and the second feedback system detect the distance of the movement of the Z axis to obtain the coordinate value of the drill point. According to the embodiment, the first feedback system and the second feedback system are arranged on the Z axis to detect the moving distance of the Z axis, so that the moving distance of the drill point is obtained, and the coordinate value of the drill point is obtained.
The first feedback system 10 includes a first grating scale 32, the first grating scale 32 is assembled on a spindle chuck of the Z axis, a first reading head 30 of the first grating scale 32 is electrically connected with the control system, the first reading head 30 is used for reading the moving distance of the first grating scale 32 along with the spindle chuck of the Z axis, and the first reading head 30 is installed on the spindle chuck of the Z axis through a first fixing seat 31. By setting the first feedback system in this way, the coordinate value of the drill point can be accurately obtained.
The second feedback system 9 comprises a second grating ruler tape 22, the second grating ruler tape is assembled on the chip suction cover 7 of the Z axis, a second reading head 20 of the second grating ruler tape 22 is electrically connected with the control system, the second reading head 20 is used for reading the moving distance of the second grating ruler tape 22 along with the chip suction cover 7 of the Z axis, and the second reading head 20 is assembled on the chip suction cover 7 of the Z axis through a second fixing seat 21. By setting the second feedback system in this way, the coordinate value of the drill point can be accurately obtained.
In step S2, the surface cover plate covered on the PCB board is grounded to make the surface cover plate have zero voltage, the drill needle is set to positive voltage, and when the drill needle contacts with the surface cover plate covered on the PCB board, an electric loop signal is formed, and the electric loop signal triggers the control system to control the first feedback system and the second feedback system to record the coordinate values of the drill needle. By means of the surface plate and the drill point thus arranged, an electrical circuit signal can be formed for transmitting signals to the control system.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (5)
1. A method for improving drilling accuracy, which is characterized in that the method is used for machining back drilling of a PCB by a machine tool, and comprises the following steps:
s1: setting a first feedback system and a second feedback system which are positioned at different heights, wherein the first feedback system and the second feedback system are used for detecting coordinate values of the drill point;
s2: controlling a machine tool spindle to enable the drill point to touch a surface cover plate covered on the PCB, and recording a first initial coordinate value H0' of the drill point touching the surface cover plate by a first feedback system;
s3: according to the first target value H0 of the first feedback system set by the control system, calculating a first difference delta H0 'between the first initial coordinate value H0' and the first target value H0;
s4: the second feedback system records a second initial coordinate value H1 ' of the drill needle touching the surface cover plate, and calculates a second difference delta H1 ' between the second initial coordinate value H1 ' and the second target value H1 according to a second target value H1 of the second feedback system set by the control system;
s5: and calculating a third difference delta H between the first difference delta H0 ' and the second difference delta H1 ', wherein when delta H=delta H0 ' -delta H1 <5um, the control system takes the H0 ' position as a back drilling starting point, controls the depth value of the drill required by the drill point for drilling, and when delta H=delta H0 ' -delta H1 ' is more than 5um, the control system takes the H1 ' position as the back drilling starting point, and controls the depth value of the drill required by the drill point for drilling.
2. A method of improving drilling accuracy as claimed in claim 1, wherein: in step S1, the first feedback system and the second feedback system are both disposed on the Z axis of the machine tool for drilling, and the first feedback system and the second feedback system detect the distance of the movement of the Z axis to obtain the coordinate value of the drill point.
3. A method of improving drilling accuracy as claimed in claim 2, wherein: the first feedback system comprises a first grating ruler, a first reading head of the first grating ruler is assembled on a spindle clamp of the Z axis and is electrically connected with the control system, and the first reading head is used for reading the moving distance of the first grating ruler along with the spindle clamp of the Z axis.
4. A method of improving drilling accuracy as claimed in claim 3, wherein: the second feedback system comprises a second grating ruler belt, the second grating ruler belt is assembled on the chip suction cover of the Z shaft, a second reading head of the second grating ruler belt is electrically connected with the control system, and the second reading head is used for reading the movement distance of the second grating ruler belt along with the chip suction cover of the Z shaft.
5. A method of improving drilling accuracy as claimed in claim 1, wherein: in step S2, the surface cover plate covered on the PCB board is grounded to make the surface cover plate have zero voltage, the drill needle is set to positive voltage, and when the drill needle contacts with the surface cover plate covered on the PCB board, an electric loop signal is formed, and the electric loop signal triggers the control system to control the first feedback system and the second feedback system to record the coordinate values of the drill needle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311628576.8A CN117677050A (en) | 2023-11-30 | 2023-11-30 | Method for improving drilling precision |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311628576.8A CN117677050A (en) | 2023-11-30 | 2023-11-30 | Method for improving drilling precision |
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| Publication Number | Publication Date |
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| CN117677050A true CN117677050A (en) | 2024-03-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311628576.8A Pending CN117677050A (en) | 2023-11-30 | 2023-11-30 | Method for improving drilling precision |
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| CN (1) | CN117677050A (en) |
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- 2023-11-30 CN CN202311628576.8A patent/CN117677050A/en active Pending
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