Three Common Drilling Methods For PCB
Via (VIA), a common hole, for opening or connecting copper foil traces between conductive patterns in different layers of a board. For example (such as blind holes, buried holes), but can not be inserted into the component feet or other copper-plated holes for reinforcement. Since the PCB is formed by stacking a plurality of copper foil layers, each of the copper foils is covered with an insulating layer such that the copper foil layers cannot communicate with each other, and signals are connected through the via holes. (pass). So there is a Chinese through hole.
Features: in order to meet the needs of customers, the through hole of the circuit board must be blocked, so that the surface resistance welding and blockage can be completed by using the whiteboard in the process of replacing the traditional aluminum plug hole. The board is stable for production. Reliable quality and perfect application. Through-holes primarily function as circuit interconnections and conduction. With the rapid development of the electronics industry, higher requirements have been placed on the manufacturing process and surface mount technology of printed circuit boards. The through hole process of the application jack should meet the following requirements: 1. There is copper in the through hole to block the soldering plug. 2. There must be tin lead in the through hole. There is a certain thickness requirement (4um). There must be no solder mask ink in the holes, resulting in hidden tin beads in the holes. 3. The through hole must have an opaque solder-proof ink plug hole, and there must be no tin ring, solder ball and flat requirements.
Blind hole: The outermost circuit in the PCB is connected to the adjacent inner layer by a plated hole. Because it is not visible, it is called blind pass. At the same time, in order to increase the space utilization between the PCB circuit layers, blind holes are applied. That is, the via hole is to one surface of the printed circuit board.
Features: Blind holes are located on the top and bottom surfaces of the board and have a certain depth for the connection between the surface line and the underlying inner line. The depth of the holes usually does not exceed a certain ratio (aperture). This type of production requires special attention to the depth of the hole (Z-axis) to be just right. If you don't pay attention, it will make the plating hole difficult, so it is almost useless. You can also use circuit layers that need to be pre-connected in each circuit layer. Drill first and finally stick them together, but require more precise positioning and alignment.
A buried via is a connection between any circuit layers inside the PCB, but is not conducted to the outer layer, nor is it a through hole that does not extend to the surface of the board.
Features: During this process, it is not possible to use the drilling method after bonding. It is necessary to drill holes in the various circuit layers. After the inner layer is partially bonded, the first plating is performed first, and finally the bonding is completed, which is more than the original conduction. Holes and blind holes require more time, so the price is also the most expensive. This process is typically only used on high density boards to increase the available space in other circuit layers.
Drilling is very important in the PCB production process and should not be sloppy. Because the drilling is to drill the required through holes in the copper clad plate to provide electrical connection and to fix the function of the device. If the operation is not suitable, there is a problem in the through hole process, the device cannot be fixed on the circuit board, the light affects the use, and the entire circuit board is scrapped, so the drilling process is very important.