CN109922603B

CN109922603B - PCB drilling method

Info

Publication number: CN109922603B
Application number: CN201910312292.5A
Authority: CN
Inventors: 万里鹏; 刘梦茹; 纪成光; 陈正清
Original assignee: Shengyi Electronics Co Ltd
Current assignee: Shengyi Electronics Co Ltd
Priority date: 2019-04-18
Filing date: 2019-04-18
Publication date: 2020-11-06
Anticipated expiration: 2039-04-18
Also published as: CN109922603A

Abstract

The invention discloses a drilling method of a PCB (printed circuit board), and relates to a manufacturing process of a printed circuit board. The drilling method comprises the following steps: superposing and fixing the upper cover plate, the PCB and the base plate; pre-drilling, wherein the diameter of a drill tool is smaller than the aperture of a hole to be drilled; and drilling step by step according to the core board material of the PCB, wherein the diameter of the drill is equal to the aperture of the hole to be drilled. According to the invention, by adjusting the laminated structure of the PTFE mixed pressing plate, the upper layer and the lower layer of the mixed pressing plate are protected by adopting auxiliary materials, fibers in the PTFE material are cut into short chips through pre-drilling and multi-step drilling and chip removal in stages, the winding of a drill bit is prevented, and the drill bit is helped to be cleaned by using drill cuttings of the non-PTFE core plate and the base plate which are mixed and pressed on the inner layer, so that a better drilling effect is achieved, and burrs on the hole wall are reduced.

Description

PCB drilling method

Technical Field

The embodiment of the invention relates to the manufacturing technology of printed circuit boards, in particular to a drilling method of a PCB.

Background

A copper clad laminate made of Polytetrafluoroethylene (PTFE) material and double-sided copper clad foil is called a PTFE core board. The multilayer mixed-compression PCB is made of PTFE core plates, and the outer surface of at least one side in the lamination is the PTFE core plates. The PTFE material is relatively soft, and the burrs mainly comprise hole opening burrs after drilling, hole wall burrs and plate edge burrs after milling. In the method for improving the drilling burrs of the PCB, aiming at the burrs of the hole opening, the use of auxiliary materials is limited by the existing general processing method, for example, the lamination mode is aluminum sheet + FR4 core board + isolation paper + PTFE multilayer mixed compression PCB + isolation paper + FR4 core board + aluminum sheet, and the like, the aluminum sheet plays a role in positioning and guiding, can prevent hole deviation, and can dissipate heat and remove dust in a drill mouth groove; the rigidity of the FR4 board plays a supporting role; the mode of stack material is favorable to reducing the production of drilling burr. Another method for improving the aperture burr is to remove the burr after the burr is generated by using an additional process or technique, such as laser ablation, mechanical plate grinding, high pressure flushing, chemical micro-etching, etc.

However, the currently limited method has no effective countermeasure for burrs generated on the inner hole wall in the drilling process.

Disclosure of Invention

The invention provides a drilling method of a PCB (printed Circuit Board), which can reduce burrs generated on a hole wall in the drilling process of a PTFE (Polytetrafluoroethylene) mixed pressure plate.

A method of drilling a PCB, comprising:

superposing and fixing the upper cover plate, the PCB and the base plate;

pre-drilling, wherein the diameter of a drill tool is smaller than the aperture of a hole to be drilled;

and drilling step by step according to the core board material of the PCB, wherein the diameter of the drill is equal to the aperture of the hole to be drilled.

The pre-drilling comprises:

and drilling through the upper cover plate and the upper-layer PTFE sub-plate, wherein the depth of drilling into the inner-layer non-PTFE sub-plate is a first preset depth, and a pre-drilled hole is obtained.

Wherein, step-by-step drilling is carried out according to the core plate material of the PCB, and the method comprises the following steps:

the PCB comprises an upper-layer PTFE sub-board, an inner-layer non-PTFE sub-board and a lower-layer PTFE sub-board;

drilling along the pre-drilled hole, wherein the circle center of the drill cutter is overlapped with the circle center of the pre-drilled hole;

in the first stage, the upper cover plate and the upper-layer PTFE sub-plate are drilled through, and the depth of drilling into the inner-layer non-PTFE sub-plate is a second preset depth;

a second stage of drilling through the inner non-PTFE sub-sheet;

and in the third stage, drilling through the lower-layer PTFE sub-plate, wherein the depth of drilling into the base plate is a second preset depth.

Or, drilling step by step according to the core board material of the PCB, including:

the PCB comprises an upper-layer PTFE sub-plate, a lower-layer PTFE sub-plate, and at least one group of a first inner-layer non-PTFE sub-plate, an inner-layer PTFE sub-plate and a second inner-layer non-PTFE sub-plate which are sequentially overlapped between the upper-layer PTFE sub-plate and the lower-layer PTFE sub-plate;

in the first stage, the upper cover plate and the upper-layer PTFE sub-plate are drilled through, and the depth of the PTFE sub-plate drilled into the first inner-layer non-PTFE sub-plate is a second preset depth;

a second stage of drilling through the first inner non-PTFE sub-sheet;

in the third stage, the inner-layer PTFE sub-plate is drilled through, and the depth of the inner-layer PTFE sub-plate drilled into the second inner-layer non-PTFE sub-plate is a second preset depth;

a fourth stage of drilling through the second inner non-PTFE sub-sheet;

and in the fifth stage, drilling through the lower-layer PTFE sub-plate, wherein the depth of drilling into the base plate is a second preset depth.

The depth of the first stage is greater than the depth of the pre-drilled hole.

The diameter of the drill knife for pre-drilling is 0.05-0.2 mm smaller than the aperture of the hole to be drilled.

The first preset depth is 0.2-0.4 mm; the second preset depth is 0.3-0.8 mm; and the first preset depth is smaller than the second preset depth.

Wherein, the upper cover plate comprises an aluminum sheet and a cover plate.

Wherein the inner non-PTFE sub-plate is an FR4 core plate.

According to the invention, by adjusting the laminated structure of the PTFE mixed pressing plate, the upper layer and the lower layer of the mixed pressing plate are protected by adopting auxiliary materials, fibers in the PTFE material are cut into short chips through pre-drilling and multi-step drilling and chip removal in stages, the winding of a drill bit is prevented, and the drill bit is helped to be cleaned by using drill cuttings of the non-PTFE core plate and the base plate which are mixed and pressed on the inner layer, so that a better drilling effect is achieved, and burrs on the hole wall are reduced.

Drawings

FIG. 1 is a flow chart of a method of drilling a hole according to one embodiment of the present invention;

FIG. 2 is a schematic diagram of a stacked structure of a PCB according to a first embodiment of the present invention;

FIG. 3 is a schematic diagram of a pre-drill according to one embodiment of the present invention;

FIG. 4 is a schematic view of a step-by-step drilling according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a stacked structure of PCBs in the second embodiment of the present invention;

FIG. 6 is a schematic diagram of step-by-step drilling according to a second embodiment of the present invention.

In the figure: 1. aluminum sheets; 2. a cover plate; 3. an upper PTFE sub-plate; 4. an inner non-PTFE daughter panel; 5. a prepreg; 6. a base plate; 7. a lower PTFE sub-plate; 8. a first inner non-PTFE daughter panel; 9. a second inner non-PTFE daughter panel; 10. the inner PTFE sub-plate.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Example one

The embodiment provides a drilling method of a PCB, which is suitable for a PCB formed by mixing and pressing a PTFE core board and other core boards, and can reduce burrs on the hole wall by drilling the PCB of the type.

The outer surfaces of two sides of the PCB are provided with PTFE core plates which comprise an upper-layer PTFE sub-plate, an inner-layer non-PTFE sub-plate and a lower-layer PTFE sub-plate to form a PTFE mixed pressing plate.

The upper PTFE sub-board and the lower PTFE sub-board can be single PTFE core board or sub-boards obtained by laminating prepregs among a plurality of PTFE core boards.

Because the PTFE material is soft, it is necessary to compress the harder inner core to provide some support. The inner-layer non-PTFE sub-board is a sub-board obtained by laminating a single FR4 core board (glass fiber epoxy resin copper clad board) or a plurality of FR4 core boards with prepregs superposed.

The inner non-PTFE daughter board may also be replaced with FR4 prepreg, limited by the number of PCB copper layers.

Fig. 1 is a flowchart of the drilling method in this embodiment, which specifically includes the following steps:

and S1, overlapping the upper cover plate, the PCB and the backing plate and fixing.

Wherein, the upper cover plate comprises an aluminum sheet and a cover plate. The cover plate is an organic hard thin plate with the thickness within 1 mm. The base plate is made of melamine or phenolic aldehyde materials.

Auxiliary material is equipped with corresponding hole like all corresponding PCB workspace's instrument hole on apron and the backing plate, with auxiliary material and PCB coincide back in proper order, through fixed modes such as pin, fixed auxiliary material and PCB, cover the aluminum sheet and fix with the sticky tape in the top.

Fig. 2 shows a laminated structure of one of the PCBs and a structure laminated with the auxiliary material. Coincide aluminum sheet 1, apron 2, upper PTFE daughter board 3, the non-PTFE daughter board 4 of inlayer, lower floor's PTFE daughter board 7 and backing plate 6 in proper order from the top down, between upper PTFE daughter board 3, the non-PTFE daughter board 4 of inlayer and the non-PTFE daughter board 7 of lower floor, fold into prepreg 5 according to the pressfitting needs.

And S2, pre-drilling.

And pre-drilling the upper cover plate and the upper-layer PTFE sub-plate, and drilling into the inner-layer non-PTFE sub-plate by a first preset depth to obtain a pre-drilled hole.

FIG. 3 is a schematic diagram of pre-drilling in an embodiment of the present invention. The diameter D of the drill tool for pre-drilling is smaller than the aperture D of the hole to be drilled, and preferably, the diameter of the drill tool for pre-drilling is 0.05-0.2 mm smaller than the aperture of the hole to be drilled. The first preset depth is 0.2-0.4 mm. The pre-drilling depth is equal to the thickness of the upper cover plate, the thickness of the upper-layer PTFE sub-plate and the first preset depth.

In the step, the cutter diameter of the pre-drilled drill cutter is small, and the drill cuttings on the PTFE layer can be effectively reduced during formal drilling as primary cutting, so that the discharge and cutting of the drill cuttings during the formal drilling are facilitated.

And S3, drilling holes step by step according to the core board material of the PCB.

The diameter of the selected drill bit is equal to the aperture D of the hole to be drilled. If the operation such as hole metallization is needed after drilling, the diameter of the drill is selected to be slightly larger than the aperture D of the hole to be drilled in order to reserve the thickness allowance of the plating layer.

And drilling the drill cutter along the pre-drilled hole, wherein the circle center of the drill cutter is overlapped with that of the pre-drilled hole.

FIG. 4 is a schematic view of step drilling in an embodiment of the present invention. The step drilling comprises the following steps:

and S31, in the first stage, drilling through the upper cover plate and the upper-layer PTFE sub-plate, wherein the depth of drilling into the inner-layer non-PTFE sub-plate is a second preset depth, and the drilling-down depth in the first stage is greater than the depth of the pre-drilled hole.

The drilling depth of the first stage is larger than the thickness of the upper cover plate, the thickness of the upper-layer PTFE sub-plate and the second preset depth. The second preset depth is 0.3-0.8 mm, and the first preset depth is smaller than the second preset depth.

In this step, the drill cutter can effectively cut the PTFE layer, and after the predrilling, the drill chip volume on the PTFE layer will effectively reduce, simultaneously, bore into the FR4 daughter board of inlayer, can discharge the drill chip on the PTFE layer through FR4 layer drill chip, clean the drill cutter.

S32, second stage, drilling through the inner non-PTFE sub-plate.

The drilling depth of the second stage is larger than the thickness of the upper cover plate, the thickness of the upper-layer PTFE sub-plate and the thickness of the inner-layer non-PTFE sub-plate.

And S33, in the third stage, drilling through the lower PTFE sub-plate, wherein the depth of drilling into the backing plate is a second preset depth.

And the drilling depth of the third stage is equal to the thickness of the upper cover plate, the thickness of the PCB and the second preset depth.

In the step, the drill bit enters the backing plate, so that the drilling cuttings on the PTFE layer can be effectively discharged through the drilling cuttings on the backing plate, and the cleanness of the drill bit is ensured.

This embodiment adopts auxiliary material to protect on the upper and lower layer of mixing the clamp plate through the range upon range of structure of adjusting the mixed clamp plate of PTFE, through boring in advance and the staged chip removal of substep drilling, cuts off into the short bits with the fibre in the PTFE material, prevents to twine the brill sword to utilize and mix the drill chip of pressing at the non-PTFE core of inlayer and backing plate, the clean brill sword of help reaches better drilling effect, reduces the pore wall burr.

Example two

As shown in fig. 5, the PCB of the present embodiment includes an upper PTFE sub-board 3, a lower PTFE sub-board 7, and at least one set of a first inner non-PTFE sub-board 8, an inner PTFE sub-board 10, and a second inner non-PTFE sub-board 9 stacked in sequence between the upper PTFE sub-board 3 and the lower PTFE sub-board 7. An aluminum sheet 1 and a cover plate 2 are overlapped on the upper side, a backing plate 6 is overlapped on the lower side, and prepregs 5 are overlapped between the daughter boards according to the pressing requirement.

Fig. 6 is a schematic view of the step-by-step drilling in the present embodiment. As shown in fig. 6, the step drilling is performed along the pre-drilled hole, and the center of the drill bit coincides with the center of the pre-drilled hole, and the step drilling includes:

and in the first stage, drilling through the upper cover plate and the upper-layer PTFE sub-plate, wherein the depth of drilling into the first inner-layer non-PTFE sub-plate is a second preset depth.

A second stage of drilling through the first inner non-PTFE sub-sheet.

And in the third stage, drilling through the inner-layer PTFE sub-plate, wherein the depth of drilling into the second inner-layer non-PTFE sub-plate is a second preset depth.

A fourth stage of drilling through the second inner non-PTFE sub-sheet.

This embodiment is applicable to the mixed clamp plate of inlayer pressfitting PTFE panel, when boring the PTFE layer, drills into the certain degree of depth on non-PTFE layer, utilizes the drill chip on the drill chip help PTFE layer on non-PTFE layer to discharge and clean the brill sword, can effectively reduce the drilling burr that PTFE mixed clamp plate, improves the pore wall quality.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A drilling method of a PCB, comprising:

superposing and fixing the upper cover plate, the PCB and the base plate;

drilling holes step by step according to the core board material of the PCB, wherein the diameter of a drill is equal to the aperture of the hole to be drilled;

the pre-drilling comprises:

drilling through the upper cover plate and the upper-layer PTFE sub-plate, wherein the depth of drilling into the inner-layer non-PTFE sub-plate is a first preset depth, and a pre-drilled hole is obtained;

the step-by-step drilling is carried out according to the core board material of the PCB, and the step-by-step drilling method comprises the following steps:

a second stage of drilling through the inner non-PTFE sub-sheet;

in the third stage, drilling through the lower-layer PTFE sub-plate, wherein the depth of drilling into the base plate is a second preset depth;

the first preset depth is 0.2-0.4 mm;

the second preset depth is 0.3-0.8 mm;

and the first preset depth is smaller than the second preset depth.

2. The method of claim 1, wherein the step drilling is performed according to a core material of the PCB, further comprising:

the inner-layer non-PTFE sub-plate comprises at least one group of a first inner-layer non-PTFE sub-plate, an inner-layer PTFE sub-plate and a second inner-layer non-PTFE sub-plate which are sequentially overlapped;

the second stage comprises:

drilling through the first inner non-PTFE sub-sheet;

drilling through the inner-layer PTFE sub-plate, wherein the depth of drilling into the second inner-layer non-PTFE sub-plate is a second preset depth;

drilling through the second inner non-PTFE sub-sheet.

3. The drilling method according to claim 1, wherein:

the depth of the first stage is greater than the depth of the pre-drilled hole.

4. The drilling method according to claim 1, wherein:

5. The drilling method according to claim 1, wherein:

the upper cover plate comprises an aluminum sheet and a cover plate.

6. The drilling method according to claim 1, wherein:

the inner non-PTFE sub-plate is an FR4 core plate.