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Drilling parameters: The setting of drilling parameters is the most important thing. If the drilling progress is too fast, the drill bit will break due to excessive force. If the drilling progress is too slow, it will increase the frequency of consumption. Because the board thickness, copper thickness, and board structure of the bus PCB boards consumed by various board manufacturers are not contrary, because the PCB needs to be set according to the detailed conditions. After planning and testing, choose the most suitable drilling parameters. For a normal drill tip of 0.3mm, the cutting progress should be 1.5-1.7m/min, and the drilling depth should be between 0.5-0.8.
2. The backing plate for the backing plate and aluminum sheet drilling requires a moderate angle, uniform thickness, flatness, and thickness difference should not exceed 0.076mm. If the backing plate is not specified for soft and hard dispersion, simply jam the drill nozzle and the backing plate is not flat. The pressure foot will not be pressed tightly, and the drill bit will twist and break, and the plate will move with it during the high and low movement of the drill bit. When the drill bit is returning to the knife, the force will not be out of balance and break. Its function:
(1) Inhibit the onset of plants in the hole.
(2) Adequately penetrate the PCB board.
(3) Increase the measurement of the drill tip 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 the inertia that is echoing is required. The drill bit becomes soft instantly when it is in contact with the drill bit. It is the position of the drill bit that is accurately positioned to be drilled, and it does not deviate the drill bit from the original hole position and cause the bit to break.
The role of aluminum sheet:
1. Prevent the occurrence of plants and scratches on the PCB board.
2. Play the role of heat dissipation and cleaning of the drill bit.
3. It can guide the trajectory of the drill bit into the PCB board to improve the accuracy of drilling.
The aluminum sheet requires a large conductivity coefficient, so that the heat generated during drilling can be quickly taken away. To increase the measurement of the drill tip, excessive use of 0.15-0.2mm thick aluminum sheet or 0.15-0.35mm aluminum alloy compound aluminum sheet, It is ineffective to prevent the drill nozzle from breaking due to poor chip removal due to the formation of low temperature during drilling.
3. The quality of the copper clad sheet material. The glass fiber cloth of the sheet material is thick, and the joint force is not good, and it will have a greater response to the broken drill nozzle. If the plate resin is not completely assembled, it will simply cause excessive scum on the hole wall, poor chip removal and break the drill tip. If there are voids in the base plate, the drill bit will be broken when the force is not symmetrical when drilling. Therefore, the sheet must be baked before drilling. The normal baking time is 4 hours/150oC±5oC
4. Drills. The time and division of the use of drills must be based on the processing methods, the quality of the cargo hole wall, and the use of drills that do not have the same type of performance. The main types of drills are 1: ST type (straight drill) 2: UC type (under cut drill) 3: ID type (inverse drill), the most rarely used at the moment is the ST type, which is actually used for paper containing paper and epoxy, Phenolic epoxy glass and other double-sided boards and PCB boards with more than four layers. The characteristic of the UC drill tip is that the tip diameter is smaller than the diameter above the head (that is, the head is larger and the body is smaller). The idea is to reduce the conflict with the hole wall during the drilling process to prevent the hole wall from passing Thick and broken needles. Choosing a supplier with timely delivery, stable quality, and perfect after-sales service is extremely important.
5. Tool function During the drilling process, it is necessary to ensure that the drilling machine is stopped in a stable and precise form. Because the vibration of the planer, the vibration of the main optical axis and the runout are too large, the COLLET design is not good or there are miscellaneous goods, the Z axis is idle, the dust removal is not good, and the (X, Y) axis movement is not good, etc., all will lead to broken drill tips. It is necessary to choose and use drilling rigs with excellent functions according to the PCB factory's own depositors and the cargo structure. Under deformed conditions, the height difference between the highest and lowest points of the machine flatness is required to be <0.125mm, and the deviation of the X and Y axis movement precision is <0.076mm.
SPINDLE static RUNOUT<2.5um. Contraction gas measurement = room temperature. Freezing point=3oC, oil residue ≤0.01mg/m3, liquid waste ≤0.1um (or else, there is water and oil in the formation of SPINDLE, reflecting the life of SPINDLE and the precision of drilling), and the suction power 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 1.3mm longer than the drill tip inside and outside. When drilling, the presser foot pad presses the aluminum sheet and then drills in. When the drill is retracted, the presser foot pad separates the plate after the drill bit is lifted, or the drill bit is simply broken. And check the precision of CNC drilling on schedule, and adjust it.
6. Working conditions The 5S request of the consumer group is higher, and the dirt is reduced. Tool marble countertops are cleaned with petroleum. Keep it clean. The measurement control of the studio is between 20oC±2oC, to ensure that the tools are in compliance with the conditions of employment, to ensure the same quality of quality, and to ensure the life of the CNC drilling machine.
The above is an introduction to the main reasons and preventive measures for broken drill tips. Ipcb is also provided to PCB manufacturers and PCB manufacturing technology.
