Types of Drilling Processes Single Pass Drill: The conventional method of drilling holes in PCBs where a bit passes through the PCB once to create a hole. Step Drill: A method to minimize bit breakage, where initially about 1/2 or 1/3 of the PCB is drilled and then the remaining portion is drilled to create the hole. Mainly used for thicker products. Double Drill: A method to enhance bit durabil..

2. Creating Vacuum in SEM Once you have completed these two steps, you are ready to place the object into the SEM machine. Open the SEM machine, place the object inside, and ensure that the door is securely closed to establish a proper vacuum. Next, press the "pump" button to initiate the vacuum. However, if the vacuum is not properly established, there could be two potential causes: The door is..