The most common drilling holes in PCB: through-hole, blind hole, buried hole. The meaning and characteristics of these three holes.
Through-hole (VIA), a common hole used to conduct or connect copper foil lines between conductive patterns in different layers of a circuit board. For example (such as blind hole, buried hole), but can not insert component leg or other reinforcement material copper plated hole. Because PCB is formed by the accumulation of many copper foil layers, each layer of copper foil will be laid with a layer of the insulation layer, so that the copper foil layer can not be communicated with each other, the link of its signal depends on the channel hole (VIA).
Characteristic is: in order to meet the needs of customers, the circuit board through-hole must be fortress hole, so that in changing the traditional aluminum plug hole technology, using white mesh to complete the circuit board surface resistance welding and plug hole, so that the production is stable, reliable quality, use more perfect. With the rapid development of the electronic industry, higher requirements have been put forward for the production process and surface mount technology of printed circuit boards.
Conducting hole for plug hole technology is applied and born, and should meet the following requirements:
Blind hole: it is to connect the outermost circuit in PCB with the adjacent inner layer by electroplating hole because it can not see the opposite side, so it is called blind pass. At the same time, in order to increase the space utilization between PCB circuit layers, blind holes are applied. This is a through-hole into the surface of the printed board.
Features: Blind holes are located on the top and bottom surfaces of the circuit board, with a certain depth, for the connection between the surface circuit and the inner circuit below, the depth of the hole usually does not exceed a certain ratio (aperture). This way of production will need to pay special attention to the depth of the hole (the Z-axis) to the right, do not pay attention to words will cause difficult hole plating so almost no factory used, can also be connected in advance to the layer in the individual circuit when the circuit was first drill hole, and then sticking together, but need more precision positioning and contrapuntal device.
Buried hole refers to the link between any circuit layer in PCB but does not conduct to the outer layer, and also does not extend to the surface of the circuit board.
Features: this process cannot be achieved by drilling after bonding, drilling must be performed in individual circuit layers, first partial bonding of the inner layer after the first electroplating treatment; finally all bonding, than the original guide hole and blind hole is more time, so the price is the most expensive. This process is usually used only on high-density boards to increase the available space for other circuit layers
In the PCB production process, drilling is very important, can not be careless. Because drilling is to drill the required holes in the copper-clad plate to provide the electrical connection, fixed device function. If the operation is improper, the process of the hole appears a problem；the device can not be fixed on the circuit board, the light will affect the use, heavy the whole board will be scrapped, so the drilling process is critical.
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