HDI board is a kind of circuit board that uses micro-blind buried hole technology and closely distributed lines. Mainly used in high-end products, the emergence and development of HDI boards have led to the emergence of light, thin, short, and small electronic products.
一、 The basic concept of HDI board
1. HDl: HighDensityInterconnectionTechnology high-density interconnection technology. It is a PCB multilayer board manufactured by the layer-up method and micro-blind buried holes.
2. Microholes: In PCBs, holes with a diameter less than 6mil (150um) are called microholes.
3. Blind hole: BlindVia, a via hole that connects the surface layer and the inner layer without going through the entire plate.
4. Buried hole: BuriedViaHole, the hole buried in the inner layer, which is not visible in the finished product, is mainly used for the conduction of the inner layer line, which can reduce the probability of signal interference; maintain the continuity of the characteristic impedance of the transmission line. Since the buried hole does not occupy the surface area of the PCB, more components can be placed on the surface of the PCB.
二、Structural classification of HDI boards
HDI has no fixed process, and the stacking and production process depends on the drilling requirements.
1. The composition of HDI drilling can be divided into: laser blind hole, machine drilled buried hole, machine drilled through hole.
2. According to the HDI process, it can be divided into
—Level process: 1+N+1
Second-stage process: 2+N+2
Third-stage process: 3+N+3
Fourth-stage process: 4+N+4
三、Advantages of HDI board
1. Higher wiring density can be achieved.
2. Reduce the area of the pad, reduce the distance from the hole to the hole, and reduce the size of the PCB.
3. Reduce the loss of electrical signals.
High-density integrated HD technology can make electronic products more miniaturized to meet people's needs for miniaturization of electronic products. At present, HDI is widely used in high-end electronic products such as mobile phones and digital cameras.
