Electronic Design - Rigid-flex board factory tells you what is the meaning of vias, blind vias and buried vias

Rigid-flex board factory tells you what is the meaning of vias, blind vias and buried vias

Via (VIA): This is a common hole used to conduct or connect copper foil lines between conductive patterns in different layers of the circuit board. For example (such as blind holes, buried holes), but can not insert component leads or copper-plated holes of other reinforced materials. Because the PCB of the rigid-flex board factory is formed by the accumulation of many copper foil layers, each layer of copper foil will be covered with an insulating layer, so that the copper foil layers cannot communicate with each other, and the signal The link depends on the via, so it has the title of via in Chinese.

The characteristic is: in order to meet the needs of customers, the through holes of the circuit board of the flexible and hard board factory must be plugged. In this way, in changing the traditional aluminum plugging process, white mesh is used to complete the solder mask and plugging of the circuit board.

So that its production is stable, the quality is reliable, and the application is more perfect. Vias mainly play the role of interconnection and conduction of circuits. With the rapid development of the industry, higher requirements are also placed on the process and surface mount technology of printed circuit boards. The process of plugging via holes is applied, and the following requirements should be met at the same time:

1. There is copper in the via hole, and the solder mask can be plugged or not plugged.

   
   

2. There must be tin and lead in the through hole, and there must be a certain thickness requirement (4um) that no solder mask ink can enter the hole, resulting in hidden tin beads in the hole.

3. The through holes must have solder mask ink plug holes, opaque, and must not have tin rings, tin beads, and flatness requirements.

Blind via: It is to connect the outermost circuit in the PCB of the rigid-flex board factory with the adjacent inner layer with electroplated holes. Because the opposite side cannot be seen, it is called blind pass. At the same time, in order to increase the space utilization between PCB circuit layers, blind holes are applied. That is, a via hole to one surface of the printed board.

Features: Blind holes are located on the top and bottom surfaces of the circuit board with a certain depth. They are used to link the surface circuit and the inner circuit below. The depth of the hole usually does not exceed a certain ratio (aperture).

This production method requires special attention to the depth of the drilling (Z-axis) to be just right. If you don’t pay attention, it will cause difficulties in electroplating in the hole, so almost no factory adopts it. You can also put the circuit layers that need to be connected in advance in the individual circuit layers. The holes are drilled first, and then glued together, but a more precise positioning and alignment device is required.