Let's first introduce the common bores in PCB: through-hole, blind hole and buried hole.The meaning and characteristics of these three holes.
VIA, a common hole used for conducting or connecting copper foil circuits between conductive graphics in different layers of the circuit board.For example (such as blind or embedded holes), but the copper plated holes cannot be inserted into the assembly leg or other reinforcing material.As PCB is formed by the stack accumulation of many copper foil layers, each layer of copper foil will be covered with a layer of insulation layer, so that the copper foil layer can not communicate with each other, and its signal link is via, so it has the Chinese name of pass-through holes.
Features: in order to meet the customer's demand, the lead hole of the circuit board must fortify the hole. In this way, in changing the traditional aluminum sheet plug hole process, the resistance welding and the plug hole of the board surface of the circuit board is completed with white net, so that the production is stable, the quality is reliable and the application is more perfect.With the rapid development of electronics industry, the pass-through hole mainly plays the role of mutual connection and pass-through of circuits. It also puts forward higher requirements on the process of printed circuit board production and surface mount technology.The process of plugging hole through hole is applied, and the following requirements should be met: 1. Inside the hole, copper can be inside, while resistance welding can be stoppered without stoppage.2. There must be tin lead in the conductive hole, and there must be a certain thickness requirement (4um). No soldering ink may enter the hole, resulting in tin beads inside the hole.3. The pass-through hole must have a soldering ink plug hole, and shall not be light-proof, and shall not have requirements such as tin ring, tin bead and leveling.
Blind hole: it is to connect the outermost circuit in the PCB to the adjacent inner layer with the electroplating hole.At the same time, in order to increase the space utilization between PCB layers, the blind hole was applied.That is, a hole in the surface of the printing plate.
Features: the blind hole is located on the top and bottom surface of the circuit board and has a certain depth, which is used for the connection between the surface circuit and the inner circuit below. The depth of the hole is usually not more than 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.
The embedded hole is the connection between any circuit layers in the PCB but does not lead to the outer layer. It is also the meaning of the conductive hole that does not extend to the surface of the circuit board.
Features: in this process, the method of drilling after bonding cannot be used. Drilling must be carried out at the time of individual circuit layers. Local bonding of the inner layer is followed by electroplating, and finally all bonding can be achieved.This process is usually only used on high-density circuit boards to increase the availability of other circuit layers
In the production process of PCB, drilling is very important.Because drilling is to drill the required hole on the copper clad plate to provide electrical connection, fixed device function.If the operation is not proper, there will be problems in the process of crossing the hole. The device cannot be fixed on the circuit board, which will affect the use of light, and the whole board will be scrapped in the heavy part. Therefore, drilling is quite important.