Special positioning bottom plate for numerical control machining of high-precision printed circuit board and machining method

Abstract

The invention relates to a special positioning bottom plate for numerical control machining of a high-precision printed circuit board and a machining method. Linear guide rails, guide grooves, scale marks, corresponding auxiliary holes and the like are machined on a conventional phenolic resin base plate by adopting a mechanical and laser combined application method. The problems that a base plate positioning machining method commonly used in the industry is low in efficiency, high in cost and poor in precision, and deviation exists between the perpendicularity between different positions of the upper surface of the base plate and a main shaft, and the deviation can directly cause cutter breaking, deviation, hole inclination, cutter abrasion and the like in the drilling machining process can be fundamentally solved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-precision printed circuit board manufacturing, and in particular to a special positioning base plate and processing method for numerically controlled machining of high-precision printed circuit boards. Background Art

[0002] Improving efficiency and reducing consumption have always been the goals pursued by the manufacturing industry. With the rapid improvement of the scientific and technological level and the increasing intensification of market competition, all walks of life are seeking ways to effectively improve their core competitiveness levels, such as business opportunity insight ability, rapid response ability, learning ability, technical level, marketing ability, service ability, risk management ability, etc., so as to sprint straight, merge and accelerate, overtake on a curve and seize more opportunities and market shares on the international track, showing their strength.

[0003] The positioning base plate is a floating workbench surface commonly used in the numerical control machining process of high-precision printed circuit boards. In order to meet the positioning and processing requirements of products of different specifications, 2-3 positioning pins need to be installed on the base plate before each drilling. If there are already positioning pins on it, in order to ensure the machining accuracy and effect, the positioning pins also need to be removed first and then reinstalled (the pins need to be replaced each time before machining a new product). Over time, when the floating workbench surface cannot be machined with new positioning holes due to the dense positioning holes on it, it must be scrapped. This kind of workbench surface is large in volume, heavy in weight, high in cost, the process of installing and removing the pins is cumbersome, and the equipment downtime is long when installing and removing the pins.

[0004] To sum up, this commonly used base plate positioning and processing method in the industry is low in efficiency, high in cost, and poor in accuracy. Coupled with the deviation in the perpendicularity between different positions on the upper surface of the base plate and the main shaft, this deviation will directly lead to various problems such as tool breakage, deviation, hole skew, and tool wear during the drilling process, and it cannot meet the requirements of the current industrial and technological development. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a special positioning base plate and processing method for numerically controlled machining of high-precision printed circuit boards.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A special positioning base plate for CNC machining of high-precision printed circuit boards proposed by the present invention includes an X-direction guide rail, X-direction screw holes, a base plate main body, Y-direction screw holes, Y-direction guide rails, guide grooves, and scale lines; the base plate main body is a rectangular plate; the X-direction guide rails are respectively arranged on both sides of the left end of the upper surface of the base plate main body; the Y-direction guide rails are respectively arranged on both sides of the bottom end of the upper surface of the base plate main body; an X-direction screw hole and a guide groove are successively arranged between the two X-direction guide rails; a Y-direction screw hole and a guide groove are successively arranged between the two Y-direction guide rails; the scale lines are respectively arranged on the upper surfaces of the X-direction guide rail and the Y-direction guide rail.

[0008] A processing method for a special positioning base plate for CNC machining of high-precision printed circuit boards, the method comprising the following steps:

[0009] S1. Use a CNC milling machine to machine the X-direction guide rail and the Y-direction guide rail at corresponding positions on the base plate main body;

[0010] S2. Use a CNC milling machine to machine the guide grooves at corresponding positions on the base plate main body, the guide grooves being through grooves, and machine precision fine-thread screw holes at the central positions on the side of the guide grooves close to the edge of the base plate main body;

[0011] S3. Use a laser CNC drill to machine scale lines on the upper surfaces of the X-direction guide rail and the Y-direction guide rail respectively, the scale lines being made by laser ablation method.

[0012] Further, the base plate main body is an epoxy phenolic backing plate with a thickness of not less than 15 mm; the X-direction guide rail and the Y-direction guide rail are formed by removing the remaining materials outside the guide rails by the material removal method.

[0013] Further, the CNC milling machine is a special CNC milling machine for PCB, and the maximum rotational speed does not exceed 100 krpm.

[0014] Further, the milling cutter of the CNC milling machine is a special PCB flat milling cutter with a diameter of Φ5.0 - Φ6.0 mm.

[0015] Further, the milling program of the CNC milling machine is compiled using the climb milling method, the feed sequence is from left to right and from bottom to top, the depth of cut per revolution is 50 - 100 μm, the back engagement of cut is 200 - 500 μm per pass, and the parallel feed path spacing is 4.0 - 4.8 mm.

[0016] Further, the scale lines are machined using a laser CNC drill; the laser CNC drill is a special CO2 laser CNC drill for PCB.

[0017] Further, the C0 2 The processing parameters of the laser CNC drill are AP0, the pulse period is 0.4 - 0.6 ms, the number of pulses is 20 - 24 shot, and the pulse width is 18 - 22 ms.

[0018] The present invention has the following beneficial effects compared with the prior art:

[0019] All kinds of equipment, tools and materials used in the processing of the device of the present invention are general-purpose equipment and materials in the industry. General enterprises can process them by themselves without external cooperation. Moreover, the processing and production are simple, convenient and flexible to use, and the manufacturing, maintenance and repair costs are relatively low. The scale lines on the guide rail are made by a laser numerical control drilling machine through the method of removing materials by ablation, and will never break or fall off, with a long service life.

[0020] At present, the traditional general positioning base plate is a positioning base plate with a thickness of about 10 - 15 mm and with dowel pins on both sides. These two dowel pins cooperate with the CNC machine tool table through a clamping system to fix the base plate. Before each drilling, first, the positioning holes need to be processed on the base plate according to the designed positions of the product positioning holes, then the prepared special dowel pins are inserted into the positioning holes, and then the production board is installed on the dowel pins. The main disadvantage of this process is that due to the different designed positions of the product positioning holes, there are more and more positioning holes on the base plate. When the product accuracy is affected, the base plate needs to be scrapped; moreover, there is a gap of 50 - 100 μm between the dowel pins used to cooperate with the production board and the product positioning holes. When the CNC machine tool table drives the base plate and the product to move at a high speed of 60 meters per minute, due to inertia, the hole position accuracy of the product will deviate. Therefore, the present invention can more prominently demonstrate its advantages in the processing of high-precision printed circuit boards. The two groups of guide rails with scale lines in the present invention can replace the dowel pins to achieve precise control of the positioning reference of the product.

[0021] The processing method proposed by the present invention can be processed and manufactured by using general-purpose PCB special equipment in the industry, and materials can be obtained locally, and both the manufacturing and maintenance costs are relatively low. Compared with the traditional mechanical processing method and material production, the processing method proposed by the present invention can reduce the production and material costs by more than 10 times. Description of the Drawings

[0022] Figure 1 It is a top view structural schematic diagram of a special positioning base plate for high-precision printed circuit board numerical control processing proposed by the present invention;

[0023] Figure 2 It is a side view sectional structural schematic diagram of a special positioning base plate for high-precision printed circuit board numerical control processing proposed by the present invention.

[0024] Among them, reference numerals: 1 - X-direction guide rail; 2 - X-direction screw hole; 3 - base plate main body; 4 - Y-direction screw hole; 5 - Y-direction guide rail; 6 - guide groove; 7 - scale line. Detailed Embodiment

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] It should be noted that in the description of the present invention, the orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "one side", "the other side", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating that the device or component must have a specific orientation, be constructed and operated in a specific orientation.

[0027] See the attached Figure 1-2 , a special positioning base plate for numerically controlled machining of high-precision printed circuit boards proposed in this embodiment, includes an X-direction guide rail 1, X-direction screw holes 2, a base plate main body 3, Y-direction screw holes 4, Y-direction guide rails 5, guide grooves 6 and scale lines 7.

[0028] Among them, the base plate main body 3 is a rectangular plate structure, and the base plate main body 3 is an epoxy resin phenolic backing plate with a thickness of not less than 15 mm.

[0029] Two X-direction guide rails 1 are provided, and are respectively arranged on the front and rear sides of the left end of the upper surface of the base plate main body 3; two Y-direction guide rails 5 are provided, and are respectively arranged on the left and right sides of the bottom end of the upper surface of the base plate main body 3; an X-direction screw hole 2 and a guide groove 6 are sequentially arranged between the two X-direction guide rails 1 along the guide rail direction; a Y-direction screw hole 4 and a guide groove 6 are sequentially arranged between the two Y-direction guide rails 5 along the guide rail direction; the scale lines 7 are respectively arranged on the upper surfaces of the X-direction guide rails 1 and the Y-direction guide rails 5.

[0030] Among them, structures such as guide rails, guide grooves, and screw holes can be respectively matched with corresponding auxiliary devices such as sliders, micrometers, and screw rods to achieve precise control of product positioning, and completely solve problems such as poor hole position accuracy caused by inertia during the high-speed movement of the product on the CNC machine tool table.

[0031] A processing method for a special positioning base plate for numerically controlled machining of high-precision printed circuit boards, the method includes the following steps:

[0032] S1. Use a CNC milling machine to machine the X-direction guide rail 1 and the Y-direction guide rail 5 at the corresponding positions on the base plate main body 3; both the X-direction guide rail 1 and the Y-direction guide rail 5 are formed by removing the remaining materials outside the guide rail by the material removal method

[0033] S2. Use a CNC milling machine to machine guide grooves 6 at corresponding positions on the main body of the base plate 3. The guide grooves 6 are through grooves, and X-direction screw holes 2 and Y-direction screw holes 4 are respectively machined at the central positions of the two guide grooves 6 close to the edge side of the main body of the base plate 3. The X-direction screw holes 2 and Y-direction screw holes 4 are both precision fine-pitch screw holes;

[0034] Among them, the CNC milling machine is a special CNC milling machine for PCB, and the maximum rotation speed does not exceed 100 krpm; the milling cutter of the CNC milling machine is a special PCB flat-end milling cutter with a diameter of Φ5.0 - Φ6.0 mm; the milling process program of the CNC milling machine is compiled in the up-milling mode, and the feed sequence is from left to right and from bottom to top. The depth of cut per revolution is 50 - 100 μm, the back engagement of cut is 200 - 500 μm per pass, and the pitch of the parallel feed path is 4.0 - 4.8 mm.

[0035] S3. Use a laser CNC drilling machine to machine scale lines 7 on the upper surfaces of the X-direction guide rail 1 and the Y-direction guide rail 5 respectively. The scale lines are made by the laser ablation method.

[0036] Among them, the laser CNC drilling machine is a special CO2 laser CNC drilling machine for PCB; the processing parameters of the CO2 laser CNC drilling machine are AP0, the pulse period is 0.4 - 0.6 ms, the number of pulses is 20 - 24 shots, and the pulse width is 18 - 22 ms.

[0037] For the processing method proposed by the present invention, the equipment used is general equipment of ordinary enterprises, and ordinary operators can complete the operation under the guidance of engineers. The processing, debugging and application are relatively convenient, and the processing effect is easy to guarantee; the scale lines 7 made by the laser ablation method for removing materials have clear scales, are not easy to be damaged, and have a long service life. Compared with the method of pasting or scribing scale lines on the surface, it has significant advantages; the laser processing parameters vary due to different materials and requirements. The relevant parameters proposed in the present invention are the best ranges obtained by engineering and technical personnel through a large amount of theoretical guidance and practical experience summary.

[0038] The following further illustrates this method through specific examples:

[0039] Prepare an epoxy resin phenolic pad with a thickness of 15 mm; detect that the size, dimensions and specifications of the epoxy resin phenolic pad meet the technical requirements, the surface is flat and smooth, and there is no obvious warping;

[0040] Prepare 6 special PCB flat-end milling cutters with a diameter of 6 mm, and confirm that the technical indicators such as the geometric angle, geometric parameters, specification model and surface state of the cutters meet the requirements;

[0041] Prepare 1 mechanical CNC milling machine, and require that the servo spindle of the CNC milling machine is a mechanical bearing, which can output a large power torque constantly at low-speed rotation, and the maximum rotation speed of the servo spindle does not exceed 100 krpm;

[0042] Use special instruments and methods to test the servo spindle clamping force, spindle diameter runout, positioning accuracy, vacuum pressure and other technical indicators of the CNC milling machine to meet the requirements;

[0043] Prepare 2 Φ3.175*16mm pins, and use special instruments to confirm that the specifications, sizes, and dimensions of the pins meet the requirements, and that the pins have a smooth surface without defects such as bending and deformation;

[0044] The milling program is compiled in reverse milling mode. The cutting sequence starts from the upper left corner of the bottom plate, from left to right and from top to bottom. The program is named dwpm.r1. The milling program of the guide groove 6 is compiled in the same way. The program is named dwdc.r2.

[0045] Prepare a Φ3.15mm diameter drill bit and confirm that all technical indicators of the drill bit meet the requirements;

[0046] Lay the epoxy resin phenolic pad flat on the table of the CNC milling machine and adjust it to a suitable position; place the drill bit at the specified position of the CNC milling machine tool disk, and the method is no different from the existing general method; according to the conventional method, call the drilling positioning hole program, execute the drilling positioning hole-installing pin instruction on the epoxy resin phenolic pad, and the depth of the positioning hole does not exceed 10mm; remove the epoxy resin phenolic pad from the table, directly rotate it 180 degrees, and place the epoxy resin phenolic pad flat on the table of the CNC milling machine in a hole-groove matching manner;

[0047] Call the milling program dwpm.r1, set the DN value to 10, the UP value to 18, and the tool drop point to the upper left corner; execute the milling instructions to machine two sets of guide rails and the bottom plate working plane by removing material;

[0048] Remove the epoxy resin phenolic pad, put a 2.5mm thick wooden paddle pad underneath, and set the DN value to 0.5; call the guide groove milling program dwdc.r2, perform the milling operation, and complete the processing of guide groove 6;

[0049] Prepare a laser CNC drilling machine scale processing program, named jgkdc.d1; lay the positioning base plate flat on the laser CNC drilling machine table, call the laser drilling program jgkdc.d1, set the optical path mode to AP0, the pulse width to 20, the shot number to 22, and the pulse period to 0.5ms; execute the laser drilling command to process the corresponding scale lines 7 on the two sets of guide rails respectively;

[0050] Use a benchtop drilling machine to machine X-direction screw hole 2 and Y-direction screw hole 4 on the side of the base plate according to the drawing requirements, and the base plate is completed.

[0051] Matters not described in detail in the present invention are all known technologies.

[0052] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A special positioning base plate for CNC machining of high-precision printed circuit boards, characterized in that: It includes an X-guide rail, an X-screw hole, a base plate body, a Y-screw hole, a Y-guide rail, a guide groove and scale lines; the base plate body is a rectangular plate; the X-guide rails are respectively arranged on both sides of the left end of the upper surface of the base plate body; the Y-guide rails are respectively arranged on both sides of the bottom end of the upper surface of the base plate body; the X-screw hole and the guide groove are arranged in sequence between the two X-guide rails; the Y-screw hole and the guide groove are arranged in sequence between the two Y-guide rails; the scale lines are respectively arranged on the upper surfaces of the X-guide rail and the Y-guide rail.

2. The method for processing a special positioning base plate for CNC machining of a high-precision printed circuit board according to claim 1, characterized in that: The method comprises the following steps: S1. Use a CNC milling machine to process the X-guide rail and the Y-guide rail at the corresponding position of the base plate body; S2, using a CNC milling machine to process a guide groove at a corresponding position of the base plate body, the guide groove is a conducting groove, and a precision fine-pitch screw hole is processed at the center position of the guide groove close to the edge side of the base plate body; S3. Use a laser numerical control drilling machine to process scale lines on the upper surfaces of the X-guide rail and the Y-guide rail respectively, wherein the scale lines are made by laser ablation.

3. A special positioning base plate for CNC machining of high-precision printed circuit boards according to claim 2, characterized in that: The bottom plate body is an epoxy resin phenolic pad with a thickness of not less than 15 mm; the X-direction guide rail and the Y-direction guide rail are formed by removing the remaining materials outside the guide rails through a material removal method.

4. The special positioning base plate for CNC machining of high-precision printed circuit boards according to claim 2, characterized in that: The CNC milling machine is a CNC milling machine specially used for PCB, and the maximum rotation speed does not exceed 100krpm.

5. The special positioning base plate for CNC machining of high-precision printed circuit boards according to claim 2, characterized in that: The CNC milling machine milling cutter is a special PCB flat head milling cutter with a diameter of Φ5.0-Φ6.0 mm.

6. The special positioning base plate for CNC machining of high-precision printed circuit boards according to claim 2, characterized in that: The milling program of the CNC milling machine is compiled in reverse milling mode, the cutting sequence is from left to right and from bottom to top, the cutting depth is 50-100 μm / revolution, the back cutting depth is 200-500 μm / time, and the parallel cutting path spacing is 4.0-4.8 mm.

7. The special positioning base plate for CNC machining of high-precision printed circuit boards according to claim 2, characterized in that: The scale lines are processed by a laser numerical control drilling machine; the laser numerical control drilling machine is a CO2 laser numerical control drilling machine specially used for PCB.

8. The special positioning base plate for CNC machining of high-precision printed circuit boards according to claim 7, characterized in that: The processing parameters of the C02 laser CNC drilling machine are AP0, pulse period 0.4-0.6ms, pulse number 20-24shot, and pulse width 18-22ms.

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