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1. PCB drilling parameters: The setting of drilling parameters is very important. If the drilling speed is too fast, the drill tip will break due to excessive force. Too slow drilling speed will reduce production efficiency. Because the thickness, copper thickness, and structure of the PCB produced by each PCB board manufacturer are different, the PCB needs to be set according to the specific situation. Through calculation and testing, the most suitable drilling parameters are selected. Generally, for a 0.3mm drill tip, the cutting speed should be 1.5-1.7m/min, and the drilling depth should be controlled between 0.5-0.8.
2. The backing plate for the backing plate and aluminum sheet drilling requires moderate hardness, uniform thickness, flatness, and the thickness difference should not exceed 0.076mm. If the backing plate is irregular in soft and hard distribution, it is easy to jam the drill tip and the backing plate is uneven. The pressure foot will not be pressed down tightly, which is the twist and break of the drill bit, and the plate will also move with it during the up and down movement of the drill bit. The drill bit will break due to the unbalanced force when the tool is returned. Its function:
(1) Inhibit the occurrence of burrs in the pores.
(2) Fully penetrate the PCB board.
(3) Reduce the temperature of the cutting edge of the drill bit and reduce the broken drill.
The aluminum sheet used for drilling must have a certain rigidity to prevent the plate from shaking when the knife is lifted, and it needs to have corresponding elasticity. The drill bit becomes soft immediately when the drill is in contact with the drill bit. The drill bit is precisely aligned with the position to be drilled, and the drill bit will not deviate from the original hole position and cause the bit to break.
The role of aluminum sheet:
1. Prevent burrs and scratches on the surface of the PCB board.
2. It plays a role of heat dissipation and drill cleaning.
3. The drill can be guided to drill into the track of the PCB board to improve the accuracy of drilling.
The aluminum sheet requires a large thermal conductivity, so that the heat generated during drilling can be quickly taken away, and the temperature of the drill bit should be reduced. You should try to use 0.15-0.2mm thick aluminum sheet or 0.15-0.35mm aluminum alloy composite aluminum sheet, which is effective Prevent the drill nozzle from breaking due to poor chip removal due to high temperature during drilling.
3. The quality of the copper clad sheet material. The glass fiber cloth of the sheet material is thick, and the bonding force is not good, which will also have a greater impact on the broken drill nozzle. If the plate resin is not completely polymerized, it is easy to produce more slag on the hole wall, poor chip removal and break the drill tip. If there is a cavity in the substrate, the drill bit will be broken due to uneven force during drilling. Therefore, the sheet must be baked before drilling. Baking time is generally 4 hours/150oC±5oC
4. Drills When using drills, drills with different types of functions must be selected according to the processing purpose, product hole wall quality requirements, and uses. The main types of drills are 1: ST type (straight drill) 2: UC type (under cut drill) 3: ID type (inverse drill), the most commonly used at present is the ST type, suitable for paper, epoxy paper, phenol Double-sided board with epoxy glass and other board materials and PCB board with four layers or less. The characteristic of the UC type drill tip is that the diameter below the tip is smaller than the diameter above the head (that is, the head is larger and the body is smaller). The design principle is to reduce the friction with the hole wall during the drilling process to prevent the hole wall from being too thick and broken. Needle. It is very important to choose a supplier with timely delivery, stable quality and perfect after-sales service.
5. Machine performance. During the drilling process, the drilling rig must be ensured to be in a stable and accurate state. Due to the vibration of the drilling machine, the vibration of the spindle and the large runout, poor COLLET design or debris, Z-axis lost motion, poor dust removal, poor (X, Y) axis movement, etc., all cause the drill tip to break, so it must be based on the PCB The board factory's own customer groups and product structure choose to use drilling rigs with good performance. Under normal circumstances, it is required that the height difference between the highest and lowest point of the machine flatness is less than 0.125mm, and the deviation of the X and Y axis movement accuracy is less than 0.076mm.
SPINDLE dynamic RUNOUT<2.5um. Compressed air temperature = room temperature. Dew point = 3oC, oil residue ≤ 0.01mg/m3, solid residue ≤ 0.1um (otherwise, there will be water and oil in SPINDLE, which will affect SPINDLE's life and drilling accuracy), and the dust suction force is within the range of 100-150Mbar. The pressure of the pressure foot should be 21-24N/CM2. The presser foot of each drill spindle should be adjusted to be about 1.3mm longer than the drill tip. When drilling, the presser foot pad presses the aluminum sheet before drilling in. When the drill is withdrawn, the presser foot pad will leave the board after the drill tip is lifted, otherwise the drill tip will be easily broken. And regularly check and adjust the accuracy of CNC drilling.
6. The operating environment has higher requirements for the 5S in the PCB production workshop to reduce the presence of dust. Machine marble countertops and beams should be cleaned with alcohol for daily maintenance. keep clean. The temperature of the operating room is controlled between 20oC±2oC to ensure that the machine works in an adapted environment, ensuring quality, and ensuring the life of the CNC drilling rig.
