CN115529728A - Drilling method for PCB - Google Patents

Abstract

The invention relates to a drilling method of a PCB, which comprises the following steps: s11, drilling a blind hole on the PCB by using a drill with the edge length size exceeding the depth size of the via hole, wherein the depth of the blind hole is H, H is less than H, and H-H is less than 0.5mm; s12, returning the drill to the outside of the blind hole; and S13, drilling through the blind hole by using a drill to form a through hole. Through drilling blind holes on a PCB (printed circuit board) and then returning the cutter to the outside of the blind holes, debris in the blind holes is discharged. When the blind hole is drilled through next step, because the drilling depth is less than 0.5mm, the generated scraps are few during drilling, so that the torque of the drill during drilling is reduced, the cutter breakage of the drill is avoided, the service life of the drill is prolonged, and the processing cost is saved. Meanwhile, the drill cutter is directly drilled from the top surface to the bottom surface of the PCB, so that the problem of deviation of a superposition part caused by twice drilling is avoided, and the drilling quality is good.

Description

Drilling method for PCB

Technical Field

The invention relates to the technical field of circuit board processing, in particular to a drilling method of a PCB.

Background

A Printed Circuit Board (PCB) is also called a Printed Circuit Board (PCB) and is a carrier for electrical connection of electronic components. The PCB board may be divided into a single panel, a double panel, and a multi-layer board. The multilayer board is formed by laminating a plurality of substrates, so that the wiring area of the whole PCB board is increased, and the requirement of graphic design is met. Meanwhile, the overall thickness of the multilayer board is also increased correspondingly. Referring to fig. 1, a via hole 10 is formed in a PCB board 1, and the via hole 10 is a through hole, so that each layer of circuit on the PCB board 1 can be conducted through the via hole 10. Therefore, in the process of manufacturing the PCB 1, the via hole 10 needs to be formed in the PCB 1 through a drilling process. For the thick PCB board 1, the diameter of the via hole 10 is small, especially when the thickness ratio t: d exceeds 20: 1, the processing difficulty of the via hole 10 is large. In the prior art, the method for processing the via hole 10 with a high thickness-diameter ratio mainly includes two methods, one of which is a positive and negative drilling method, namely, a drill with a length dimension not exceeding a hole depth dimension is used for respectively drilling holes from two opposite side surfaces of the PCB board 1, and finally the via hole 10 is obtained. The processing method has the following disadvantages: in the drilling process, the PCB 1 needs to be turned over and aligned with the hole positions, so that the positions of two drilling processes are coaxial as much as possible. Therefore, the machining method is high in clamping difficulty, and the superposed position of two times of drilling holes has a deviation problem, so that the aperture exceeds the standard, and further subsequent machining is influenced. The other drilling method comprises the following steps: and directly drilling one side surface of the PCB 1 by using a drill with the length dimension exceeding the hole depth dimension. The method does not need turning over, so the problem of over standard aperture is avoided. However, the drill bit has a slender structure, and when drilling is performed, chips are continuously generated, and friction is generated between the chips and a hole wall, so that the drill bit is subjected to a large torque, and the bit is easily broken. Especially, when the drill bit drills through the via hole 10, the torque applied to the drill bit is the largest, and the axial pressure is suddenly reduced, so that the stress on the drill bit is unbalanced and the drill bit is broken, thereby increasing the processing cost.

Disclosure of Invention

The invention aims to provide a drilling method of a PCB, which has good drilling quality and low processing cost.

In order to achieve the purpose, the invention adopts the following technical scheme:

the drilling method of the PCB is used for processing a via hole on the PCB, the via hole penetrates through the top surface and the bottom surface of the PCB, the depth of the via hole is H, and the drilling method is characterized by comprising the following steps of:

s11, drilling a blind hole on the PCB by using a drill with the edge length size exceeding the depth size of the via hole, wherein the depth of the blind hole is H, H is less than H, and H-H is less than 0.5mm;

s12, returning the drill cutter to the outside of the blind hole, and discharging debris in the hole;

and S13, drilling through the blind hole by the drill cutter to form the via hole.

Further, in step S1, a difference between the depth H of the via hole and the depth H of the blind hole is 0.2 to 0.3mm.

Further, in step S1, the drill cutter drills the blind hole in multiple steps, and in each step of drilling, the drill cutter returns to the outside of the blind hole after drilling at a set depth, and discharges debris in the hole.

Furthermore, when drilling in each step, the drilling depth of the drilling tool to the PCB is smaller than 2mm.

Further, the drilling speed of the drill when drilling the PCB is V1, the tool returning speed of the drill is V2, and V2 is greater than V1.

Further, in two adjacent times of drilling the PCB, the drill is stopped from being lowered to a position close to the previous drilling end point after the drill is returned, the distance between the drill and the previous drilling end point is 0.05-0.1 mm, and then the drill is started for drilling.

Further, the cutting speed of the drill from the cutting tool to the position close to the drilling end point of the previous time is V3, and V3 is more than V1.

Further, when the drill bit drills to the drilling end point each time, the drill bit stops cutting and starts to return after the rotation time T is kept.

Further, the method also comprises the following steps:

and S10, before drilling, clamping the PCB on a workbench, fixing an aluminum plate on the top surface of the PCB, and fixing a base plate on the bottom surface of the PCB.

Further, a suction device is provided, and debris generated in the drilling process of the drill bit is cleaned by the suction device.

Compared with the prior art, the invention has the beneficial effects that:

according to the processing method of the PCB, the blind hole is drilled on the PCB, the distance between the bottom of the blind hole and the drilled residual amount is less than 0.5mm, and then the cutter is turned back to the outside of the blind hole to discharge the scraps in the hole. When the blind hole is drilled through next step, because the drilling depth is less than 0.5mm, the generated scraps are few during drilling, so that the torque of the drill during drilling is reduced, the cutter breakage of the drill is avoided, the service life of the drill is prolonged, and the processing cost is saved. Meanwhile, the drill cutter directly drills from the top surface to the bottom surface of the PCB, the problem of deviation of a superposition position caused by twice drilling is avoided, and the drilling quality is good.

Drawings

Fig. 1 is a schematic view of a via hole of an embodiment.

Fig. 2 is a schematic diagram of the PCB board drilling process of the embodiment.

Fig. 3 is a partial schematic view of the PCB board drilling process of the embodiment.

Fig. 4 is a schematic diagram of a process of drilling a machined hole according to an embodiment.

In the figure:

1. a PCB board; 10. conducting holes; 11. machining a hole; 2. an aluminum plate; 3. a backing plate; 4. a work table; 5. a main shaft; 6. drilling a cutter;

100. a first drilling end point; 200. a second drilling end point; 300. a third drilling end point; 400. a fourth drilling end point.

Detailed Description

In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings.

As shown in fig. 1 and fig. 2, the present invention provides a method for drilling a PCB, which is used to process a via hole 10 in a PCB 1, wherein the via hole 10 penetrates through the top and bottom surfaces of the PCB 1, and the via hole 10 is used to connect a multi-layer circuit in the PCB 1. The depth of the via hole 10 is the same as the thickness of the PCB board 1, and is H. The via hole 10 is processed by the following steps:

s11, drilling a blind hole on the PCB 1 by using the drill 6 with the edge length exceeding the depth dimension of the via hole 10, wherein the depth of the blind hole is H, H is less than H, and H-H is less than 0.5mm;

s12, returning the drill 6 to the outside of the blind hole;

and S13, drilling the blind hole by the drill bit 6 to form the through hole 10.

It will be appreciated that the via 10 is not drilled directly through at one time when drilling. Instead, a blind hole having the same diameter and the same axis as the via hole 10 is drilled in the PCB 1. The depth H of the blind hole is less than the depth H of the via hole 10, i.e. the via hole 10 is not drilled through, and the distance from the bottom of the blind hole to the bottom of the via hole during drilling is less than 0.5mm. And after the blind hole is drilled, the drill bit 6 retreats and exits from the blind hole, and the aim of the step is to enable the scraps generated in the drilling of the blind hole to be completely or mostly discharged out of the blind hole, so that the torque increase of the drill bit 6 caused by the friction between the scraps and the hole wall when the rest part is drilled is avoided. After the debris is removed, the drill bit 6 is lowered into the blind hole again to drill the remainder of the bottom of the blind hole and drill through the blind hole to form the final via 10. Since the depth of the remaining portion of the bottom of the blind hole is less than 0.5mm, few chips are generated when drilling this portion, and the chips hardly affect the torque of the drill 6. Meanwhile, the drill bit 6 can also play a role in cooling and radiating in the process of returning. Thus, during drilling of the drill bit 6 through a blind hole, the torque to which the drill bit 6 is subjected is reduced, as well as the temperature, which in turn reduces the risk of cutting.

Optionally, in order to avoid the influence of the debris in the hole on the stress of the drill 6 when drilling through the via hole 10, the residual amount of the bottom of the blind hole may be reduced as much as possible, in this embodiment, the difference between the depth H of the via hole 10 and the depth H of the blind hole (i.e., the residual amount of the bottom of the blind hole) is 0.2-0.3 mm.

Optionally, when drilling the blind hole, the drilling operation is performed in multiple steps, and the drilling depth of the drill 6 to the PCB board 1 is less than 2mm in each step of drilling. And the drill 6 returns to the outside of the blind hole after drilling to a set depth. By controlling the drilling depth during each step of drilling, the quantity of the fragments in the hole is controlled, and meanwhile, the fragments in the hole are timely discharged through the cutter returning, so that the stress load of the drill cutter 6 is favorably reduced, and the risk of cutter breaking of the drill cutter 6 is further reduced.

Optionally, the drilling speed of the drill 6 when drilling the PCB board 1 is V1, the drilling speed can be adaptively selected according to the hardness of the material, and the drilling speed V1 in this embodiment is 1.5-2.5 m/min. The tool returning speed of the drill 6 is V2, namely the tool returning speed is the speed of stopping feeding after the drill 6 drills to a set depth, and the drill 6 moves from the bottom of a drilled hole to the outside of the hole. The back-cut speed V2 in this embodiment is 15 to 20m/min. The tool returning speed V2 is greater than the drilling speed V1, so that the drill 6 can move out of the hole quickly to discharge chips, and the total working hour of drilling operation can be shortened. In the two adjacent times of drilling the PCB 1, the drill 6 is lowered to a position close to the previous drilling end point after returning, and the distance between the drill 6 and the previous drilling end point is 0.05-0.1 mm. The drilling end point is the position reached after the drill bit 6 drills the PCB board 1 once. For example: the drilling tool 6 drills the PCB 1 for the first time to form a blind hole with the depth of 1mm, and the bottom position of the blind hole is the drilling end point of the first drilling; the blind hole is entered again after the drill bit 6 is turned back to carry out the drilling for the second time, the drilling depth is 1.5mm, then the bottom position of the blind hole after the second drilling is the drilling terminal point of the second drilling, the distance from the second drilling terminal point to the opening of the hole is 2.5mm, and the distance from the second drilling terminal point to the first drilling terminal point 100 is 1.5mm. It should be noted that the drilling depth is the distance from the beginning of cutting the PCB board 1 to the end of cutting the PCB board 1 during one drilling process by the drill 6, and the process generates chips. In this embodiment, after the drill bit 6 is turned back, the drill bit is quickly lowered to a position close to the previous drilling end point, and the distance between the drill bit and the previous drilling end point is 0.05-0.1 mm, so as to prevent the drill bit 6 from directly impacting the bottom of the blind hole and breaking the drill bit 6. The cutting speed of the drill 6 from the cutting to the position close to the last drilling end point is V3, and V3 is greater than V1. Since the PCB board 1 is not cut in the process of descending the drill bit 6 to the drilling end position, the descending speed V3 can be properly increased compared with the drilling speed V1 to shorten the idle running time of the drill bit 6 in the hole, and in the embodiment, the descending speed V3 is 4-6 m/min.

Alternatively, when the drill 6 drills to the drilling end point, the drill 6 stops for a time T before returning. In this embodiment, the stay time of the drill 6 is 0.05 to 0.1s. During the dwell time T, the drill 6 continues to rotate to ensure the quality of the hole wall near the drilling end position.

Optionally, before drilling, the PCB 1 is clamped on the worktable 4, an aluminum plate 2 is fixed on the top surface of the PCB 1, and a backing plate 3 is fixed on the bottom surface of the PCB 1, so that the PCB 1 is clamped between the aluminum plate 2 and the backing plate 3. In the process of drilling the PCB 1, the aluminum plate 2 and the backing plate 3 are drilled simultaneously. It will be appreciated that the purpose of the shim plate 3 is to space the PCB board 1 from the table 4 to avoid the drill blade 6 from drilling through the PCB board 1 onto the table 4. The hardness of the shim plate 3 should be much lower than that of the PCB board 1 so that the shim plate 3 only serves as an isolation without causing a large resistance to the drill bit 6. The aluminum plate 2 plays a role in clamping and fixing the PCB 1, and plays a role in lubrication and heat dissipation. Aluminum plate 2 is coated with the lubricant, can play the lubrication to brill sword 6 in drilling process, and simultaneously, aluminum plate 2 has good heat conductivity, and the heat accessible aluminum plate 2 that brill sword 6 produced during drilling dispels the heat. Therefore, when drilling the via hole 10 in the PCB 1, the drilling work is performed by clamping the PCB 1, the aluminum plate 2 and the backing plate 3 as a whole. The drill 6 drills the aluminum plate 2, the PCB 1 and the backing plate 3 from top to bottom in sequence, wherein the backing plate 3 does not penetrate through the drill.

In order to ensure that the scraps generated in the drilling process can be discharged from the drilled blind hole, a suction device is also provided, and the scraps generated in the drilling process of the drill bit 6 are cleaned by the suction device. The suction port of the suction device is positioned in the area near the drill bit 6, when the drill bit 6 returns to the outside of the blind hole, the scraps in the blind hole can be sucked into the suction port under the suction action of the suction device, and the purpose of cleaning the scraps is achieved.

The present drilling method is described in detail below with a specific example. Referring to fig. 1 to 4, the drill 6 is mounted on a main shaft 5, and the main shaft 5 is used to drive the drill 6 to rotate about its own axis direction and move in a vertical manner. The present drilling method is used to process the via hole 10 on the PCB board 1. The method comprises the following specific steps:

s10, clamping; an aluminum plate 2 is fixed on the top surface of the PCB 1, a backing plate 3 is fixed on the top surface of the PCB 1, and the three are clamped and fixed on a workbench 4 by utilizing a clamping tool. The thickness t of the PCB board 1 is 4mm, the thickness of the aluminum plate 2 is 0.2mm, and the thickness of the backing plate 3 is 2mm. During drilling, the PCB 1, the aluminum plate 2 and the backing plate 3 are drilled integrally. Therefore, in this embodiment, the PCB board 1, the aluminum board 2, and the backing board 3 are combined together to form a processing board, and the processing hole 11 is drilled in the processing board by the drill 6. Referring to fig. 3, the machining hole 11 is composed of a through hole on the aluminum plate 2, a via hole 10 on the PCB board 1, and a blind hole on the backing plate 3. Wherein, the depth of the through hole on the aluminum plate 2 is 0.2mm, the depth of the via hole 10 on the PCB plate 1 is 4mm, the cushion plate 3 does not drill through, the blind hole on the cushion plate 3 is 0.8mm, namely the total depth of the whole processing hole 11 is 5mm. And drilling a machining hole 11 with the depth of 5mm on the machining plate by using the drill 6.

S11, drilling a blind hole on the processing board by using the drill 6 with the edge length exceeding 5mm, wherein the drill 6 does not drill through the PCB 2. The depth of the blind hole is 3.83mm, and the bottom of the blind hole is 0.37mm away from the through hole 10. When the blind hole is drilled, drilling is carried out in three steps, as shown in fig. 4, the arrow direction in the drawing is the movement direction of the drill bit 6, the drilling is carried out to a first drilling end point 100 in the first step, the drilling depth is 1mm, and the total depth from the first drilling end point 100 to a hole opening is 1mm; the second step of drilling to a second drilling end point 200, wherein the drilling depth is 1.44mm, and the total depth from the second drilling end point 200 to the hole is 2.44mm; the third step is drilled to a third drilling end point 300 with a drilling depth of 1.39mm and a total depth of the third drilling end point 300 to the bore of 3.83mm. After each drilling step, the drill bit 6 is returned to the hole opening so as to discharge the debris in the hole.

And S12, after the drill bit 6 drills to the third drilling end point 300, the drill bit 6 returns to the position of the hole to discharge the debris in the hole.

S13, the drill bit 6 continues to descend, the blind hole is drilled through to form a through hole 10, and the base plate 3 is drilled for 0.8mm.

In this embodiment, the steps of drilling the blind hole and finally drilling the through blind hole are performed continuously, that is, the drilling of the hole 11 is completed in four steps in total, the blind hole is drilled in the first three steps, and the PCB board 1 is drilled in the fourth step. As shown in table one, one upward or downward movement of the drill 6 is a sequence, wherein the first drilling step comprises the steps 1 and 2, and the second drilling step comprises the steps 3-6; the third step of drilling comprises steps 7-10; the fourth drilling step comprises steps 11-14. In the first table, the lower cutter is the downward movement of the drill 6, the return cutter is the upward movement of the drill 6, the rotation speed is the rotation speed of the spindle 5 and the drill 6, and the falling speed and the return speed are the movement speeds of the drill 6 in the vertical direction when the lower cutter or the return cutter is in the first table.

When the drilling is carried out in the first step, the drill bit 6 is lowered by 1mm, the drilling depth is 1mm, the drill bit 6 drills to a first drilling end point 100, then the drill bit 6 returns to a hole, and chips are discharged;

during the second step of drilling, the drill 6 is lowered by 0.95mm and is separated from the first drilling end point by 100 mm by 0.05mm, so that the drill 6 is prevented from directly hitting the bottom of the hole. Continuing to lower the drill by 1.5mm after the drill 6 returns to the position of 0.01mm, wherein in the process of lowering the drill, the drill 6 drills to a second drilling end point 200 with the drilling depth of 1.44mm, and then returning the drill 6 to the position of the hole opening to discharge scraps;

and during the third step of drilling, the lower cutter of the drill 6 is 2.34mm, and the distance between the lower cutter and the second drilling end point 200 is 0.1mm, so that the drill 6 is prevented from directly colliding the bottom of the hole. Continuing to lower the drill by 1.5mm after the drill 6 returns by 0.01mm, wherein in the process of lowering the drill, the drill 6 drills to a third drilling end point 300 with the drilling depth of 1.39mm, and then returning the drill 6 to the hole opening to discharge scraps;

and during the fourth step of drilling, the drill bit 6 is lowered by 3.73mm and is separated from the third drilling end point 300 by 0.1mm, so that the drill bit 6 is prevented from directly colliding the bottom of the hole. And after the cutter of the drill 6 is turned back by 0.01mm, the cutter is turned down by 1.28mm, in the cutter turning process, the drill 6 drills to a fourth drilling end point 400 with the drilling depth of 1.17mm, the PCB 1 is drilled through, and the through hole 10 is machined.

Watch 1

In this embodiment, when the drill 6 is lowered and retracted, the spindle 5 drives the drill 6 to rotate.

The remarkable effects of the embodiment are as follows: according to the drilling method, the blind hole is drilled on the PCB 1, the distance between the bottom of the blind hole and the drilled residual amount is less than 0.5mm, and then the cutter is returned to the outside of the blind hole to discharge the debris in the hole. When the blind hole is drilled in the next step, due to the fact that the drilling depth is less than 0.5mm, few chips are generated during drilling, so that the torque of the drill 6 during drilling is reduced, the drill 6 is prevented from being broken, the service life of the drill 6 is prolonged, and the machining cost is saved. Meanwhile, the drill bit 6 is directly drilled from the top surface to the bottom surface of the PCB board 1, so that the problem of deviation of a superposition position caused by twice drilling is avoided, and the drilling quality is good.

The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.

Claims (10)

1. A drilling method of a PCB board is used for processing a via hole on the PCB board, the via hole penetrates through the top surface and the bottom surface of the PCB board, the depth of the via hole is H, and the drilling method is characterized by comprising the following steps:

s11, drilling a blind hole on the PCB by using a drill with the edge length size exceeding the depth size of the via hole, wherein the depth of the blind hole is H, H is less than H, and H-H is less than 0.5mm;

s12, returning the drill to the outside of the blind hole, and discharging scraps in the hole;

and S13, drilling through the blind hole by the drill cutter to form the via hole.

2. The method for drilling a PCB of claim 1, wherein in step S1, the difference between the depth H of the via hole and the depth H of the blind hole is 0.2-0.3 mm.

3. The PCB board drilling method of claim 1, wherein in step S1, the drill cutter drills the blind hole in multiple steps, and in each step of drilling, the drill cutter returns to the outside of the blind hole after drilling a set depth, and discharges chips in the hole.

4. The method of claim 3, wherein the drill has a drilling depth of less than 2mm for the PCB board at each step of drilling.

5. The method for drilling the PCB according to claim 3, wherein the drilling speed of the drill for drilling the PCB is V1, the back cutting speed of the drill is V2, and V2 is more than V1.

6. The PCB drilling method of claim 5, wherein in two adjacent times of drilling the PCB, the drill is stopped after being returned to the previous drilling end point, the distance between the drill and the previous drilling end point is 0.05-0.1 mm, and then the drill is started to drill.

7. The method for drilling the PCB according to claim 6, wherein the cutting speed of the drill to the position close to the previous drilling end point is V3, and V3 > V1.

8. The method for drilling the PCB according to claim 6, wherein when the drill stops the lowering of the drill and starts the returning of the drill after a rotation time T is kept when the drill reaches a drilling end point every time.

9. The method of drilling a PCB panel as recited in claim 1, further comprising:

and S10, before drilling, clamping the PCB on a workbench, fixing an aluminum plate on the top surface of the PCB, and fixing a base plate on the bottom surface of the PCB.

10. The method for drilling the PCB of claim 1, wherein a suction device is provided, and the suction device is used for cleaning up the chips generated during the drilling process of the drill.

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