Microwave Tech - Printed circuit board shape processing technology

The appearance of printed circuit board processing is one of the difficulties of printed circuit board processing, most of the printed circuit board is rectangular shape, but quite a lot of printed circuit board has a special appearance.

1., The printed circuit board shape processing method: ⑴ milling shape. The use of CNC milling machine processing shape, need to provide milling shape data and the corresponding pipe hole file, these data are provided by the programmer, because the PCB plate spacing can't be very large, generally about 3mm, so the milling cutter diameter is generally 3mm. First, drill the pipe position hole on the milling machine pad, fix the printed board and the milling machine pad with the pin, and then mill the shape data to mill the shape; 2 punch shape. The use of punch punching shape, need to use a mold, and the mold on the pipe position nail and printed board pipe position hole corresponding, generally choose φ3.0mm hole for the pipe position hole; 3 "V" slots. The printed board is cut into several parts connected to each other along the "V" groove line designed by the "V" groove cutter; 4 drill shape. Use a drill press to drill along the contour line. Usually the opening of the "V" groove and the drill shape are only used as an auxiliary means of machining.

2, The selection of contour processing method. The selection of contour machining method is usually based on the customer's requirements. The shape of the shape and the processing of the batch is related to the general choice of milling shape, milling shape data, to pay attention to the selection of the knife point and the direction of the knife. To ensure that the cutting direction of the knife and the effective shape of the cutting direction into 180O, so milling shape and milling groove in the opposite direction of the knife, milling shape of the knife point is generally selected from the hole near the corner of the pipe, in order to reduce the influence of the knife and the action of the knife on the shape; In the same way, if the inner groove has a convex Angle, then milling the lower cutting point of the inner groove is selected in the convex Angle; If the inner groove has no convex Angle, the lower cutter point is selected at the radius of the milling cutter on both sides of the inner groove. In addition, when cutting at the next knife point, because the right Angle side of the printed board has been milling out, the extrusion of the milling cutter to the plate will make the right Angle deformation, from the deformation to the shape, so the general milling shape, add a radius of 0.8mm in the four corners of the plate, so that the right Angle deformation into the shape. When it is impossible to add pipe hole in the printed board unit, add pipe hole in the side of the panel, add lifting point between the printed circuit board unit, and mill the shape, and file to remove the lifting point. Punch shape can adapt to the needs of mass production, processing efficiency is high, usually the choice of pipe hole shape processing quality and processing efficiency has a greater impact.

3, "V" groove and drill shape are very effective auxiliary means of shape processing. Among them, opening "V" groove is a more common auxiliary means of shape processing. When the PCB unit size is small, to reduce the milling time, can be spelled several PCB as a unit, and milling and then open a "V" shape groove, this not only improved the efficiency of the contour machining, but also conducive to plate cleaning and product packaging, also improve the utilization rate of the sheet metal for added tube hole and smaller printed circuit board, It can also reduce the number of lifting points (filing off the lifting point is a very troublesome job), which is very beneficial to the larger plate batch. When customers require a process edge or a variety of plate samples, put together, open "V" groove is the preferred shape processing. Open "V" slot although the advantages of high efficiency, but by the equipment (only refers to our "V" slot cutting machine), "V" slot spacing can not be too large, also can not open along the broken line "V" slot. Compared with this, although drilling shape is slower, it can overcome the above difficulties, but also to overcome the disadvantages of milling shape milling cutter diameter is larger, if the customer requirements of PCB unit spacing beyond the width of the open "V" slot, along the small unit plate plate add stamp holes (a series of holes with adjacent hole spacing greater than the hole diameter of about 0.2-0.5mm, Hole diameter is less than 1.0mm) can meet customer requirements; There is a customer to a variety of plate together to open a "V" groove, can add stamp hole between the printing, if you have any width of the printed circuit board d less than the lack of the diameter of the milling cutter, milling shape cannot take to processing, and the process can take many times to drill to implementation, milling frame only when milling shape, object graph 4 two tangent shadow zone of cutter will not be able to process, Using different sizes of drilling tool with drilling processing, and then with milling shape, it can complete the shape processing; The front introduces the processing method of adding lifting point between the printed circuit board and filing to remove the lifting point after milling the shape. If the stamp hole is added to the ink shape line of the lifting point, the difficulty of filing the lifting point can be greatly reduced. The plate has an inner slot. Such as 3.0mm milling cutter shape, if the board slot width is less than 8mm, the corresponding inner corner of the brightness of 3/8, if the board Angle put -φ1.5mm hole, and then milling shape, small inner corner of the slot width of 3/16, reduced the inner corner, if the customer is still not satisfied, can also be put less than 1.0mm hole, then put -φ1.5mm hole, Make the inner circle Angle less than 0.5mm hole, make the inner circle Angle less than 0.5mm.

4., The placement of the pipe hole is an important factor in shape processing. Punching shape and milling shape is a common method of shape processing, which is the machining efficiency of punching shape is very high, but they are inseparable from the corresponding pipe hole, sometimes the placement of the pipe hole shape processing has a great impact. Usually, two tube holes are added to the printed board unit, which are generally placed on the diagonal of the board. In principle, the farther away the positioning is, the better. However, for the long or wide plate and the wide difference between the length and width, a tube hole is generally placed every 200mm or so along the edge of the board. In addition, for some special shapes, the number of pipe holes will be more than two, and the position is not necessarily in the diagonal, if there is a process edge in the customer's technical data, the pipe hole is best added to the process edge, or in the plate Angle to choose two holes in the diameter of 2.0-4.0mm nonmetallic positioning holes. Strong shape tube hole placement is very important, to improve the utilization rate of the mold and the labor productivity, make the same shape but different wiring of printed circuit board using the same mold, the mold design, choose general tube mounting holes of a hole, such as technological edge, is on the edge of the process, it tends to full consultation with customer technical experts. Whether rushed or milling shape appearance, we all like add tube in a hole in PCB unit (or some sort of hole for tube hole), but unfortunately there are some customers are not allowed to add tube on the plate holes and unable to choose certain types of holes on the plate for tube hole, we have to adopt external pipe machining shape, namely in printed circuit board unit plus tube hole. If there is an internal gap in the appearance of the PCB unit, we can add the pipe position hole into the internal gap, and add a stamp hole on one side of the gap to connect with the PCB unit. After milling the shape, break off the small piece of the internal gap, file to burr, and punch the shape can also be used in the same way to add pipe hole; If the printed circuit board units have empty slot tube hole additive, slot, slot within three edge after salt/milling processing, on the other side with stamp hole connected to the printed circuit board units, appearance is processed, break the slots to small and medium-sized pieces, such as customer agree to stamp hole center and the groove edge centre, file burr process can be avoided. In order to ensure the inner fillet, when punching the shape, the four corners of the groove can be rushed out, and the middle part of the groove side is connected with the plate through the stamp hole. Another block structure is at the edge of the plate and process (process block edge is superior than process), process modules are connected to the PCB unit with the stamp hole, tube hole is added on the technology block, blunt/milling shape after the bye to process block, smooth burr, which can reduce the number of lifting point, when the contour machining, can greatly improve the machining efficiency, but add craft piece can make makeup utilization rate of decline. When punching the shape, the plate can not add the mold general pipe hole, and the customer does not agree to add stamp hole, the plate or the plate is missing, the mold general pipe hole is added at the inner slot, and the special pipe hole is added in the printed circuit board unit by milling out the inner slot or missing.

With the development of printed circuit board design, shape processing technology is also developing, some of the above summary of my work, although not necessarily reasonable for all PCB shape processing, but for many PCB manufacturers is very useful.