1、 Processing method of printed board shape: ⑴ milling shape. When machining the profile with NC milling machine, it is necessary to provide milling profile data and corresponding pipe position hole files. These data are provided by programmers. Since the splicing spacing of printed boards cannot be large, which is generally about 3mm, the diameter of milling cutter is generally 3mm. First drill the pipe position hole on the base plate of the milling machine, fix the printed board and the base plate of the milling machine with a pin, and then mill the profile with the milling profile data; 2. Punching profile. The die is required to use the punch to cut the shape, and the pipe position nail on the die corresponds to the pipe position hole of the printed board, which is generally selected φ The hole of about 3.0mm is used as the pipe position hole; 3. Open “V” slot. The “V” slot cutting machine is used to cut the printed board into several parts connected with each other along the “V” slot line designed by the printed board; 4 drill profile. Use the drilling machine to drill holes along the contour line. Usually, the “V” groove and drilling profile are only used as auxiliary means of machining.
2、 Selection of contour machining method. The selection of shape processing method is usually related to the customer’s requirements. The shape of the profile is related to the batch of processing. Generally, the milling profile is selected. When compiling the milling profile data, pay attention to the selection of cutting point and cutting direction. Ensure that the cutting direction is 180 degrees from the cutting direction of the effective profile. Therefore, the milling profile is opposite to the cutting direction in the milling groove. The cutting point of the milling profile is generally selected at a corner close to the pipe position hole to reduce the impact of cutting and starting action on the profile; Similarly, if the inner groove has a convex corner, the cutting point of milling the inner groove is selected at the convex corner; If there is no convex corner in the inner groove, the cutting point shall be at the milling cutter radius from both sides of the inner groove. In addition, when starting at the cutting point, because one side of the right angle of the printed board has been milled, the extrusion of the milling cutter on the board will deform the right angle from deformation to shape. Therefore, generally, when milling, a fillet with a radius of 0.8mm is added to the four corners of the board to deform the right angle into shape. When it is impossible to add pipe position holes in the printed board unit, add pipe position holes at the edge of the splicing board, and add lifting points between the printed board units. After milling the shape, file the lifting points with a file. The punching profile can meet the needs of mass production and has high machining efficiency. Generally, the selection of pipe position hole has a great impact on the profile machining quality and machining efficiency.
3、 “V” groove and drill profile are very effective auxiliary means for profile machining. Among them, opening “V” groove is a commonly used auxiliary means of shape machining. When the unit size of the printed board is small, in order to reduce the milling time, several printed boards can be assembled into one unit, and the “V” groove can be opened after milling the shape, which not only improves the efficiency of shape processing, but also is conducive to board cleaning and product packaging, but also improves the utilization rate of board materials. For the printed board with small size and no pipe hole, the number of lifting points can be reduced (filing the lifting point is a very troublesome job), which is very beneficial to large quantities of plates. When customers require process edges or multiple plate samples to be assembled together, opening “V” groove is the preferred shape processing method. Although opening “V” groove has the advantage of high efficiency, restricted by the equipment (only referring to our “V” groove cutting machine), the spacing of “V” groove can not be too large, nor can it be opened along the fold line “V” groove. Compared with this, although the drilling shape is slow, it can overcome the above difficulties and the disadvantage of large diameter of milling cutter. If the printed board unit spacing required by the customer exceeds the width of opening “V” groove, stamp holes shall be added between small unit panels (the spacing between adjacent holes is greater than a series of holes with a hole diameter of about 0.2-0.5mm, and the hole diameter is less than 1.0mm) It can meet the customer’s requirements; in addition, when the customer can’t open the “V” slot when putting a variety of boards together, it can be in the printing room (such as printed board a and printed board B) Add stamp holes. If the printed board has an internal defect with a width D less than the diameter of the milling cutter, it can not be processed by milling the outline, but can be processed by drilling for many times. When milling the outline, only milling the outer frame, and the shadow area where the two circles of the object are tangent, the milling cutter can not be processed. Use drilling cutters of different sizes to process by drilling, and then cooperate with the milling outline, the outline processing can be completed. As described earlier, in printing Add lifting points between plates and file the lifting points after milling the shape. If stamp holes are added to the ink contour line of the lifting points, the difficulty of filing the lifting points can be greatly reduced. If this plate has an inner groove. If milling the shape with a 3.0mm milling cutter, if the groove width is less than 8mm, the corresponding inner circle angle accounts for 3 / 8 of the brightness. If the plate angle is placed- φ 1.5mm hole, and then milling the shape. The small inner circle angle accounts for 3 / 16 of the groove width, which reduces the inner circle angle. If the customer is still dissatisfied, you can put holes less than 1.0mm first, and then- φ 1.5mm hole, so that the inner circle angle is less than 0.5mm hole, so that the inner circle angle is less than 0.5mm.
4、 The placement of pipe position hole is an important factor in shape machining. Punching profile and milling profile are common methods of profile machining. They have high machining efficiency, but they are inseparable from the corresponding pipe position hole. Sometimes the placement of pipe position hole has a great impact on profile machining. Generally, two pipe position holes are added in the printed board unit, which are generally placed on the opposite corner of the board. In principle, the farther the distance is, the better the positioning is. However, for the board with great difference in length or width and length and width, a pipe position hole is generally placed every 200mm along the board edge. In addition, for some special shapes, the number of pipe position holes will be more than two, and the position is not necessarily on the opposite corner. If there is a process edge in the customer’s technical data, the pipe position hole is best added on the process edge, or two non-metallic holes with an aperture of 2.0-4.0mm are selected as positioning holes at the plate corner. The first mock exam is very important for the placement of punch holes. To improve the utilization ratio and productivity of the mould, the same type of PCB with the same shape but different wiring is used. When the mould is designed, the general installation hole is selected as the pipe hole, if the technology side is added, the technology side should be added to the mold. Regardless of the punching or milling shape, we like to add pipe position holes in the printed board unit (or select a certain type of holes as pipe position holes), but unfortunately, some customers are not allowed to add pipe position holes in the board and cannot select a certain type of holes as pipe position holes in the board. We have to adopt the external pipe position processing shape, that is, add pipe position holes in the printed board unit. If there is an inner gap in the shape of the printed board unit, we can add the pipe position hole to the inner gap, and add a stamp hole on one side of the gap to connect with the printed board unit. After milling the profile, break off the small pieces at the inner notch, file and deburr, and punch the profile by the same method; If there is a hollowed out slot in the printed board unit, the pipe position hole can be added to the inner slot. The three sides of the inner slot are processed by punching / milling, and the other side is connected with the printed board unit with stamp holes. After the shape processing, break off the small pieces in the slot. If the customer agrees, the center of the stamp hole can coincide with the center of the slot edge, which can avoid the burring process. In order to ensure the fillet, when punching the shape, the four corners of the groove can be punched away, and the middle part of one side of the groove is connected with the plate through the stamp hole. The other structure is to process the process block at the board edge (the process block is better than the process edge). The process block is connected with the printed board unit with stamp holes, and the pipe position holes are added to the process block. After punching / milling the shape, break off the process block and file the burrs, which can reduce the number of lifting points. When punching the shape, the processing efficiency will be greatly improved, but the processing block will reduce the utilization rate of panel assembly. When punching the shape, if it is impossible to add the pipe position hole for the mold in the board, and the customer does not agree to add the stamp hole, the pipe position hole for the mold shall be added at the inner groove, and the special pipe position hole for milling the inner groove or inner defect shall be added in the printed board unit.
With the development of printed circuit board design, shape processing technology is also developing. Although the above summary of my work may not be reasonable for all printed circuit board shape processing, it is very useful for many printed circuit board producers.