KR101470359B1 - Drilling device and drill bit thereof - Google Patents

Abstract

Disclosed is a drill processing device for drilling a hole in a predetermined position on a printed circuit board and a drill bit suitable for this.
The drill bit has a body with a double blade,
One of the double blades has a helix angle of 45-55 degrees, and the other has a helix angle of 45 degrees,
The web thickness of the front end surface formed at the front end of the body is 0.105 mm, and a web taper is formed to have a different diameter of the drill bit along the length direction of the drill bit, and the degree of the web taper is the drill. The diameter of the drill bit is 0.165 mm from the tip of the bit to 1.5 mm, and the diameter of the drill bit from 1.5 mm to 4 mm is 0.180 mm.

Description

Drilling device and drill bit suitable therefor {Drilling device and drill bit thereof}

The present invention relates to a printed circuit board (Printed Circuit Board) manufacturing apparatus, and more particularly, to a drill processing apparatus for drilling a hole in a predetermined position on a printed circuit board and a drill bit suitable for the same.

In general, a printed circuit board (hereinafter referred to as PCB) is a multi-layer board manufactured for the purpose of device mounting in order to construct an electronic system circuit, and the material is a composite made of a resin, glass fiber, or copper foil layer. It is made of materials. In order to mount a semiconductor device such as an IC, LSI, etc. on such a PCB, hole processing is usually performed by a small-diameter drill for PCB.

The process of drilling a hole in the printed circuit board is referred to as a drilling process. To this end, a plurality of printed circuit boards are stacked and fixed using a substrate fixing device, and then a printed circuit using a drill machine equipped with a drill bit A drill processing device is used to drill a hole in a predetermined portion of the substrate.

1 shows a configuration of a conventional drill processing apparatus. Referring to FIG. 1, a conventional drill processing apparatus includes a drilling machine 1 having a pressure foot and a drill bit, and a substrate fixing apparatus having an entry board and a back-up board ( 2).

A plurality of printed circuit boards are stacked-up between the entry board and the backup board of the substrate fixing device 2, and drilling is performed on a predetermined portion of the printed circuit board by a drill bit. The pressure foot prevents the substrate from bending when the drill bit penetrates the printed circuit board. The entry board prevents the copper foil of the printed circuit board from being damaged from the pressure foot of the drilling machine and also prevents upper burrs. The backup board is used to prevent lower burrs and to prevent equipment from being damaged, and a bakelite material is used.

Currently, the required hole in the printed circuit board is small-diametered every year, and in recent years, the hole processing with a diameter of 0.4 mm or less occupies most. In addition, cardiovascular processing, in which the depth of the hole is more than ten times the diameter of the drill, is increasing.

In the drilling process of the printed circuit board, the main factors include drill stiffness and chip evacuation, and the quality of the machining holes such as the accuracy of the hole position and the roughness of the inner wall of the hole can be improved. Even if it is decided, it is not an exaggeration.

FIG. 2 shows a drill bit used in the apparatus shown in FIG. 1. 2, the conventional drill bit 10 is made of a shank (shank, 12), the body (body, 14).

The shank 12 is a part forming the body of the drill bit 10, and the body 14 is formed or coupled to one side of the shank 12. A helical cutting edge is formed on the surface of the body 14 to process the workpiece. The spiral cutting edge has a constant twist angle over the entire body 14, and the twist angle of the cutting edge is called a helix angle.

In the PCB machining drill, when the spiral angle is 45°, the primary face angle (γ1) formed on the outermost end face (tip) of the body 14 is generally set to 10° to 12°. This main surface angle varies depending on the material and processing characteristics of the PCB (including soft metal), but is basically determined by the spiral angle.

In addition, the tip angle (θ1, Point angle,) is approximately 120˚ to 130˚ depending on the characteristics of the substrate 　 material. It is a situation where it is manufactured by fixing it at ˚.

When mounting the drill bit to a drilling machine, a color ring can be used to match different types of drill bits to a constant length. The color ring supports the drill bit to be snapped to a length suitable for the spindle chuck of the drilling machine.

FIG. 3 shows the tip of the drill bit shown in FIG. 2. Referring to FIG. 3, the tip portion 16 has a chisel edge 22, a main flank or primary face 24, and a secondary flank or secondary face 26. The main surface 24 becomes the front end surface of the cutting edge, and the auxiliary surface 26 becomes the front end surface of the flute. On the other hand, the inclination angle of the main surface 24 is called a primary angle, the inclination angle of the auxiliary surface 26 is called a secondary angle, and the thickness of the chisel edge 22 is called web thickness. do.

On the other hand, the tip surface is inclined at a predetermined angle from the chisel edge 22 to the outer circumferential surface of the body. The degree of inclination of the tip surface is referred to as a point angle.

On the other hand, these drill bits are classified into ST (Straight) type, UC (Under cut) type, and ID (Inverse Diameter) type according to the appearance, diameter, and shape of the machining hole.

Figure 4 shows the shape of the ST type, UC type, ID type drill bits.

Referring to FIG. 4, a portion in which a drill bit diameter is determined becomes a margin of a flute, ST type has a drill bit diameter equal to a flute diameter, and UC type The diameter of the drill bit is smaller than the diameter of the flute, and in the ID type, the diameter of the drill bit is larger than the diameter of the shank.

On the other hand, the ST type has more polishing times than the UC type and has excellent hole position accuracy, but the area of contact with the hole inner wall is large, so the quality of the hole inner wall is weak. On the other hand, the UC type has a small area of contact with the inner wall of the hole, so the quality of the inner wall of the hole is excellent.

On the other hand, as the use of hazardous substances in electrical and electronic products is restricted, production of raw materials containing halogen group elements is limited. When a halogen-free raw material is used, the wear and breakage rate of the drill bit increases, resulting in reduced workability. Accordingly, there is a need for a method capable of effectively reducing wear and damage of a drill bit when using a halogen-free raw material.

In order to increase the productivity of the drilling process, it is required to maintain the hole quality and increase the number of stacks.

According to the specifications of the conventional drill bit, considering the hole quality, it was possible only up to 4 stacks. That is, in order to realize productivity improvement by increasing the number of stacks, it is necessary to change and develop detailed specifications of drill bits. Here, the number of stacks refers to the number of printed circuit boards that are simultaneously processed in one drilling process, that is, the number of printed circuit boards stacked on the substrate fixing device.

On the other hand, in the substrate fixing device, aluminum foil and water-soluble material are used as the entry board, and a board made of bakelite material is used as the backup board.

However, the bakelite backing board has a disadvantage that it is difficult to center when drilling because the hole quality is poor.

The present invention has been devised in order to meet the above requirements, and an object thereof is to provide a drill processing apparatus capable of providing the same quality when improving the number of stacks during PCB drill processing.

Another object of the present invention is to provide a drill bit of an improved structure capable of increasing the number of stacks during PCB drilling.

Drill processing apparatus according to the present invention for achieving the above object

In the drill processing device for processing a hole in a predetermined position on the printed circuit board,

A drill machine equipped with a drill bit for hole drilling of 0.25 Φ; And

A stacking and fixing a plurality of printed circuit boards that are drilled by the drill bit, and includes a substrate fixing device having an entry board and a backup board,

Here, the drill bit

Has a body with a double blade,

One of the double blades has a helix angle of 45° to 55°, the other has a helix angle of 45°,

The web thickness of the tip portion formed at the tip of the body is 0.105 mm, and the degree of web taper is 0.165 mm from the tip of the drill bit to 1.5 mm, and 0.180 mm from 1.5 mm to 4.0 mm. It is characterized by.

Here, it is preferable that the backup board of the substrate fixing device is made of melamine material.

Drill bit according to the present invention for achieving the above object is

In the drill bit provided for processing a hole of 0.25Φ in a predetermined position of a plurality of printed circuit boards stacked on the substrate holding device,

Has a body with a double blade,

One of the double blades has a helix angle of 45-55 degrees, and the other has a helix angle of 45 degrees,

The web thickness of the front end surface formed at the front end of the body is 0.105 mm, and a web taper is formed to have a different diameter of the drill bit along the length direction of the drill bit, and the degree of the web taper is the drill. The diameter of the drill bit is 0.165 mm from the tip of the bit to 1.5 mm, and the diameter of the drill bit from 1.5 mm to 4 mm is 0.180 mm.

.

The drill bit according to the present invention has a double-edged configuration, whereby the cutting force increases and the bit breakage rate decreases.

In addition, the drill bit according to the present invention increases the Web Thickness specification to 0.105 mm, thereby contributing to the improvement of wear of the drill bit.

In addition, the drill bit according to the present invention is 0.165mm from the tip of the drill bit to 1.5mm from the tip of the drill bit, and is increased to 0.180mm from 1.5mm to 4.0mm, which helps in stiffening the drill bit and damages the drill bit. It is a factor that can be alleviated.

The drill bit according to the present invention has an effect of reducing wear and damage even on a printed circuit board made of a halogen-free raw material.

1 shows a configuration of a conventional drill processing apparatus.
FIG. 2 shows a drill bit used in the apparatus shown in FIG. 1.
FIG. 3 shows the tip of the drill bit shown in FIG. 2.
Figure 4 shows the shape of the conventional ST type, UC type, ID type drill bits.
5A to 5C illustrate detailed specifications of a conventional drill bit and a drill bit according to the present invention.
6 shows a drill bit with a double blade according to the invention.
7 shows the structure of a drill processing apparatus according to the present invention.
8 shows a process of stacking up a printed circuit board using an entry board and a backup board.
9 shows the equipment required for the test.
10 shows processing conditions in the use of the drill bit according to the invention.
11 shows the results of testing using a drill bit according to the invention.
FIG. 12 shows the results applied to actual mass production products based on the test results shown in FIG. 11.
FIG. 13 shows a result of comparing the number of stacks of a drill bit according to the present invention with an existing drill bit based on the test result of FIG. 12.
14 shows the processing accuracy test result when the melamine material backup board according to the present invention is used.
15 shows a comparison measurement result of the hole machining accuracy when using a melamine back-up board according to the present invention.
16 shows the inner wall state of the hole and the surface state after processing when the drill bit and the backup board of the present invention are applied.

Hereinafter, the configuration and operation of the present invention will be described in detail with reference to the accompanying drawings. The present invention focuses on developing specifications of drill bits and finding optimum processing conditions for improving the number of stacks during PCB drilling.

5A to 5C illustrate detailed specifications of a conventional drill bit and a drill bit according to the present invention.

5A to 5C, the drill bit according to the present invention (USF type) has the largest feature of the double-edged configuration, thereby increasing the cutting force and decreasing the bit breakage rate. Here, one of the double blades has a helix angle of 45° to 55°, and the other has a helix angle of 45°.

In addition, the web thickness specification has been increased to 0.105 mm, contributing to improved wear of the drill bit. In addition, a web taper is formed so that the diameter of the drill bit is different along the length direction of the drill bit, and the precision of the web taper is 1.565 mm from the tip of the drill bit and the diameter of the drill bit is 0.165 mm, 1.5 mm. Since then, the diameter of the drill bit has been increased to 0.180 mm from 4 mm, which helps to strengthen the drill bit and is a factor that can effectively reduce the breakage of the drill bit.

6 shows a drill bit with a double blade according to the invention.

Referring to FIG. 6, the drill bit 600 according to the present invention has one long chip flute 45 and one short chip flute 44, and the spiral angles of the two grooves are different from each other. In other words, it is changed from the separated state to the joined state.

Here, the spiral angle of the long chip groove 45 is 45° to 55°, and the spiral angle of the short chip groove 44 is preferably 45°.

7 shows the structure of a drilling machine according to the invention. The drill processing apparatus 700 according to the present invention includes a drilling machine 72 having a pressure foot and a drill bit, and a substrate fixing apparatus 74 having an entry board and a back-up board. ).

Referring to FIG. 7, a pressure foot is attached to the drilling machine 72 and serves to prevent the substrate from bending when the drill bit penetrates the substrate. When preparing for drilling, adjust the height of the pressure foot so that the drill tip is on the entry board.

The entry board is intended to protect the substrate from the pressure foot of the drilling machine and to prevent burrs in the upper layer. The backup board is used to prevent burrs in the lower floor and to prevent abnormality of the equipment.

8 shows a process of stacking up a printed circuit board using an entry board and a backup board. Referring to FIG. 8, a stack guide hole is processed in a printed circuit board, and after stacking the printed circuit board, a guide pin is inserted into the stack guide hole to fix the stacked printed circuit boards. The stack guide hole serves to fix the printed circuit boards during lamination and provides reference coordinates during drilling.

Example

The test results of the drill bit and the conventional drill bit according to the present invention are as follows.

9 shows the equipment required for the test.

Referring to FIG. 9, TEST processing facilities, roughness (inner wall roughness) 　 measurement facilities, and processing accuracy measurement facilities are shown. Using these facilities, we drill and check the quality of the processed holes.

10 shows processing conditions in the use of the drill bit according to the invention.

In Figure 10, No.hitting refers to the number of holes drilled by drilling, and the number of stacks means the number of printed circuit boards stacked on the substrate fixing device. In addition, CPK (Process Capability Index) refers to the quality improvement capability produced by a process in a controlled state, that is, a distribution range represented by a product produced in a standardized process.

11 shows the results of testing using a drill bit according to the invention.

Referring to FIG. 11, it can be seen that the drill bit according to the present invention ((USF Type) is 16.37um, the hole roughness is less than 25um) and the machining accuracy is superior to that of the existing drill bits, NH, SN, and WQ. .

FIG. 12 shows the results applied to actual mass production products based on the test results shown in FIG. 11. In FIG. 12, New bit represents a drill bit used for drilling for the first time, and abrasive bit represents a drill bit in which the tip portion is polished for reuse. The drill bit is not used only once, and the worn tip is processed and reused by polishing, and the number of polishing indicates the number of such machining.

As a result of the test, when using the drill bit according to the present invention, the hole roughness and the processing accuracy are good, so 5Stack processing is possible compared to the conventional 4Stack processing. .

FIG. 13 shows a result of comparing the number of stacks of a drill bit according to the present invention with an existing drill bit based on the test result of FIG. 12.

Referring to FIG. 13, it can be seen that in the case of the new bit and the 4th and 5th polishing compared to the conventional method, results improved by 1Satck are obtained. That is, it can be seen that the drill bit according to the present invention has achieved a drill process productivity improvement of about 14% compared to a conventional drill bit.

14 shows the processing accuracy test results when the melamine material backup board according to the present invention is used. Referring to FIG. 14, it can be seen that the hole processing accuracy is improved by about 10% as compared with a conventional bakelite backing board.

15 shows a comparison measurement result of the hole machining accuracy when using the melamine back-up board according to the present invention.

16 shows the inner wall state of the hole and the surface state after processing when the drill bit and the backup board of the present invention are applied. Referring to Figure 16, it can be seen that the hole inner wall state and the processing state of the backup board are good.

12...shank 14...body
44...long chip groove 45...short chip groove
72...Drilling machine 74...Board fixing device

Claims (3)

delete delete In the drill bit provided for processing a hole having a diameter of 0.25mm at a predetermined position of a plurality of printed circuit boards laminated on the substrate holding device,
Has a body with a double blade,
The body has one long chip flute and one short chip flute,
The spiral angle of the long chip groove is 45° to 55°, and the spiral angle of the short chip groove is 45°,
The web thickness of the tip portion formed at the tip of the body is 0.105 mm, and a web taper is formed so that the diameter of the drill bit is different along the length direction of the drill bit. The precision of the drill bit is characterized in that the diameter of the drill bit is 0.165 mm from the tip of the drill bit to 1.5 mm, and the diameter of the drill bit from 1.5 mm to 4 mm is 0.180 mm.

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