Drilling method for printed circuit board (PCB) with high thickness-diameter ratio

Abstract

The invention discloses a drilling method for a PCB (Printed Circuit Board) with a high thickness-diameter ratio. The drilling method comprises the following steps of a preparation process; and a front blind hole drilling process: a printed board overturning process and a back through hole drilling process. When a printed board with the high thickness-diameter ratio is drilled, pre-drilling and secondary hole forming are conducted on one side face of the drilling position of the printed board, then overturning is conducted, pre-drilling and secondary hole forming are conducted, the phenomenon that burrs are prone to being formed during drilling with the high thickness-diameter ratio is avoided, and meanwhile drilling precision is greatly improved due to the fact that drilling is conducted on the two faces twice; in addition, aluminum sheets are respectively arranged on the drilling surfaces of the printed board to serve as cover plates, deviation caused by copper foil drilling slipping is prevented, and the drilling precision can be further improved. Therefore, the method has the advantages of high drilling precision, smooth hole wall, no burr and the like, the product quality is ensured, the cost is saved, and the product quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of PCB printed board processing, and specifically relates to a printed board drilling method, in particular to a printed board drilling method with a high aspect ratio. Background Art

[0002] When the PCB board thickness is large (above 4mm) and the drilling hole diameter requirement is small (below 0.3mm), that is, when the thickness-to-diameter ratio is greater than 12, the existing conventional drilling method is still used. Not only is the tool susceptible to wear, but the drilled holes are often burred and have low precision, which affects product quality and affects subsequent finishing. Summary of the invention

[0003] In order to overcome the above defects, the present invention provides a method for drilling holes in a printed circuit board with a high aspect ratio, which is not only less prone to burrs but also has high drilling accuracy.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A method for drilling a PCB printed board with a high aspect ratio, assuming that the thickness of the printed board to be drilled is H, the diameter of the hole to be drilled is D, and H / D ≥ 12, comprises the following steps:

[0006] Step 1, preparation: fix the printed circuit board to be drilled on a workbench, and place an aluminum sheet on its upper side as a first cover plate;

[0007] Step 2, drilling blind holes on the front side: first, corresponding to the position to be drilled on the front side of the printed circuit board, with its center as the hole center, drill a first pre-drilled hole with a diameter of 0.5D to 0.8D and a depth of 0.10H ≤ ≤ 0.15H; then, based on the first pre-drilled hole, drill a blind hole with a diameter of D and a depth of 0.5H to 0.6H;

[0008] Step 3, flipping the printed board: flipping the printed board completed in step 2 by 180 degrees, and fixing it again on the workbench described in step 1, and setting a coated aluminum sheet as a second cover plate on the flipped upper side of the printed board;

[0009] Step 4, drilling a through hole on the back side: First, at the position where a hole is to be drilled on the back side of the printed circuit board, with its center as the hole center, drill a second pre-drilled hole with a diameter of 0.5D to 0.8D and a depth of 0.10H ≤ ≤ 0.15H; then, based on the second pre-drilled hole, drill a hole with a diameter of D and a depth of 0.4H to 0.5H, the bottom of which is connected to the blind hole to form a through hole, and the drilling is completed.

[0010] As a further improvement of the present invention, in step 1, the printed circuit board is fixed to the workbench by positioning pins or bolts.

[0011] As a further improvement of the present invention, in step 2, based on the first pre-drilled hole, a three-step drilling method is used to drill a blind hole with a diameter of D and a depth of 0.4H to 0.6H.

[0012] As a further improvement of the present invention, in step 4, based on the second pre-drilled hole, a three-step drilling method is used to drill a hole with a diameter of D and a depth of 0.6H to 0.4H, the bottom of which is connected to the blind hole to form a through hole.

[0013] The beneficial effects of the present invention are as follows: when drilling a printed circuit board with a high aspect ratio, the present invention first performs pre-drilling and secondary drilling on one side of the printed circuit board where the hole is to be drilled, and then flips the printed circuit board for pre-drilling and secondary drilling, thereby solving the burr phenomenon that is easily formed when drilling holes with a high aspect ratio, and at the same time, the secondary drilling on both sides greatly improves the drilling accuracy; in addition, aluminum sheets are respectively arranged on the drilling surfaces of the printed circuit board as cover plates to prevent deviation caused by slipping of the copper foil during drilling, which can further improve the drilling accuracy. Therefore, the present invention has the advantages of high drilling accuracy, smooth hole wall, no burrs, etc., which ensures the quality of the product, saves costs, and improves the product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the first step of step 2 of embodiment 1 of the present invention;

[0015] Figure 2 This is a schematic diagram of the second step of step 2 of embodiment 1 of the present invention;

[0016] Figure 3 This is a schematic diagram of step 3 of Example 1 of the present invention;

[0017] Figure 4 This is a schematic diagram of the first step of step 4 of embodiment 1 of the present invention;

[0018] Figure 5 This is a schematic diagram of the second step of step 4 of Example 1 of the present invention. DETAILED DESCRIPTION

[0019] A preferred embodiment of the present invention is described in detail below in conjunction with the accompanying drawings.

[0020] Embodiment 1:

[0021] A printed circuit board has a thickness of 6.0 mm, a through hole to be processed has a diameter of 0.25 mm, and an aspect ratio of 24. The following steps are used when drilling:

[0022] Step 1, Preparation:

[0023] The printed circuit board to be drilled is fixed on a workbench by means of positioning pins, and a common aluminum sheet is fixed on the upper side as a first cover plate;

[0024] Step 2, Drill blind holes on the front:

[0025] First, at the location where the hole is to be drilled on the front of the printed circuit board, use a 0.20mm drill bit to drill the first pre-drilled hole 1 with a diameter of 0.20mm and a depth of 0.8mm. Figure 1 ;

[0026] Then, with the center of the first pre-drilled hole as the center, use 0.25mm and drill in three steps to drill a blind hole 2 with a diameter of 0.25mm and a depth of 3.0mm, see Figure 2 ;

[0027] Step 3, flip the printed circuit board:

[0028] Turn the printed circuit board 180° after completing step 2, and drill area 3. Figure 3 , and fix it again on the workbench described in step 1, and at the same time fix the coated aluminum sheet as the second cover plate on the upper side of the turned over printed board;

[0029] Step 4, drill holes on the reverse side:

[0030] First, at the position where the hole needs to be drilled on the reverse side of the printed circuit board, use a 0.20mm drill bit to drill a hole in one step, and drill a second pre-drill with a diameter of 0.20mm and a depth of 0.8mm. Figure 4 ;

[0031] Then, based on the second pre-drilled hole, a 0.25 mm drill bit is used to drill holes in three steps to form a hole 5 with a diameter of 0.25 mm and a depth of 3.0 mm, which is connected to the blind hole obtained in step 2 to form a through hole. Figure 5 , the drilling is completed.

[0032] If there are multiple holes to be processed on the printed circuit board, the first pre-drilling and blind hole processing of all holes on the front side are completed at the same time in step 2, and then the second pre-drilling and final through-hole drilling of the back side are completed in step 4.

[0033] Embodiment 2:

[0034] A printed circuit board has a thickness of 4.0 mm, a through hole to be processed has a diameter of 0.25 mm, and an aspect ratio of 16. The following steps are used when drilling:

[0035] Step 1, Preparation:

[0036] The printed circuit board to be drilled is fixed on a workbench by means of positioning pins, and a common aluminum sheet is arranged on the upper side thereof as a first cover plate;

[0037] Step 2, Drill blind holes on the front:

[0038] First, at the location where the hole needs to be drilled on the front of the printed circuit board, use a 0.15mm drill bit to drill the first pre-drilled hole with a diameter of 0.15mm and a depth of 0.5mm.

[0039] Then, using 0.25mm as the center of the first pre-drilled hole, drill a blind hole with a diameter of 0.25mm and a depth of 2.0mm in three steps;

[0040] Step 3, flip the printed circuit board:

[0041] The printed circuit board after step 2 is turned over 180 degrees and fixed again on the workbench described in step 1, and a layer of coated aluminum sheet is fixed on the upper side of the turned printed circuit board as a second cover plate;

[0042] Step 4, drill holes on the reverse side:

[0043] First, at the position where a hole needs to be drilled on the reverse side of the printed circuit board, with the center thereof as the hole center, a 0.15 mm drill bit is used to drill a hole in one step, and a second pre-drilled hole with a diameter of 0.15 mm and a depth of 0.5 mm is drilled;

[0044] Then, based on the second pre-drilled hole, use a 0.25mm drill bit to drill holes in three steps to drill a hole with a diameter of 0.25mm and a depth of 2.0mm to connect with the blind hole obtained in step 2 to form a through hole, thus completing the drilling.

[0045] If there are multiple holes to be processed on the printed circuit board, the first pre-drilling and blind hole processing of all holes on the front side are completed at the same time in step 2, and then the second pre-drilling and final through-hole drilling of the back side are completed in step 4.

[0046] The drilled holes obtained in the above-mentioned embodiments 1 and 2 were observed to have no burrs, and the drilling accuracy was measured to be within 0.01 mm.

[0047] Many specific details are described in the above description to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited to the specific implementation disclosed above. At the same time, any person familiar with the art can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for drilling holes in a PCB with a high aspect ratio, assuming that the thickness of the printed board to be drilled is H, the diameter of the hole to be drilled is D, and H / D ≥ 12, characterized in that: The following steps are involved: Step 1, preparation: fix the printed circuit board to be drilled on a workbench, and place an aluminum sheet on its upper side as a first cover plate; Step 2, drilling blind holes on the front side: first, corresponding to the position to be drilled on the front side of the printed circuit board, with its center as the hole center, drill a first pre-drilled hole with a diameter of 0.5D to 0.8D and a depth of 0.10H ≤ ≤ 0.15H; then, based on the first pre-drilled hole, drill a blind hole with a diameter of D and a depth of 0.5H to 0.6H; Step 3, flipping the printed board: flipping the printed board completed in step 2 by 180 degrees, and fixing it again on the workbench described in step 1, and setting a coated aluminum sheet as a second cover plate on the flipped upper side of the printed board; Step 4, drilling a through hole on the back side: First, at the position where a hole is to be drilled on the back side of the printed circuit board, with its center as the hole center, drill a second pre-drilled hole with a diameter of 0.5D to 0.8D and a depth of 0.10H ≤ ≤ 0.15H; then, based on the second pre-drilled hole, drill a hole with a diameter of D and a depth of 0.4H to 0.5H, the bottom of which is connected to the blind hole to form a through hole, and the drilling is completed.

2. The method for drilling a printed circuit board with a high aspect ratio according to claim 1, characterized in that: In the step 1, the printed circuit board is fixed on the workbench by means of positioning pins or bolts.

3. The method for drilling a printed circuit board with a high aspect ratio according to claim 1, characterized in that: In the step 2, based on the first pre-drilled hole, a three-step drilling method is used to drill a blind hole with a diameter of D and a depth of 0.4H to 0.6H.

4. The method for drilling a printed circuit board with a high aspect ratio according to claim 3, characterized in that: In step 4, based on the second pre-drilled hole, a three-step drilling method is used to drill a hole with a diameter of D and a depth of 0.6H to 0.4H, the bottom of which is connected to the blind hole to form a through hole.

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