PCB Tech - The difference between high density board (HDI board) and ordinary circuit board

The definition of high density board (HDI board) refers to the microvia (Microvia) with the hole diameter below 6mil (0.15mm), the hole ring diameter (HolePad) below 0.25mm, the contact density is above 130 points/square inch, and the wiring density is less than Printed circuit boards above 117 inches/square inch, and whose line width/spacing is less than 3mil/3mil. Generally speaking, HDI board have the following advantages:

1. Can reduce PCB cost: When the density of PCB increases more than eight-layer board, it is manufactured with HDI board, and its cost will be lower than that of the traditional complex pressing process.

2. Increase circuit density: The interconnection of traditional PCB boards and parts must be connected through the lines and through-hole conductors drawn around the QFP (fan-in and fan-out), so these lines need to occupy some space. The microvia technology can hide the wiring required for interconnection to the next layer. The bonding pads and leads between different layers are directly connected by blind holes in the pads, without fan-in and fan-out wiring. Therefore, some soldering pads (such as mini-BGA or CSP small ball soldering) can be placed on the outer board surface to accept more parts, which can increase the density of the circuit board. At present, many mobile phone boards of high-function small wireless phones use this new type of stacking and wiring method.

3. Conducive to the use of advanced assembly technology: The general traditional drilling technology cannot meet the needs of small parts of the new generation of fine lines due to the size of the pad (through hole) and mechanical drilling. With the advancement of microvia technology, designers can design the latest high-density IC packaging technologies, such as Arraypackage, CSP, and DCA (DirectChipAttach), into the system.

4. Have better electrical performance and signal accuracy: The use of microvia interconnection can not only reduce signal reflection and crosstalk interference between lines, and enable the circuit board circuit design to increase more space, due to the microvia The nature of the physical structure is that the holes are small and short, so the effects of inductance and capacitance can be reduced, and the exchange noise during signal transmission can also be reduced.

5. Better reliability: because of the thinner thickness and 1:1 aspect ratio of micro-holes, the reliability of signal transmission is higher than that of ordinary through-holes.

6. Improved thermal properties: The insulating dielectric material of the HDI board has a higher glass transition temperature (Tg), so it has better thermal properties. 20 years of professional circuit board design, high-reliability design and mass production product advertising. Professional circuit board design has 20 years of experience in electronic design to help you design products that are truly market-tested.

7. It can improve radio frequency interference/electromagnetic wave interference/electrostatic discharge (RFI/EMI/ESD): the micro-hole technology allows the circuit board designer to shorten the distance between the ground layer and the signal layer to reduce radio frequency interference and electromagnetic wave interference; on the other hand, it can Increase the number of grounding wires to prevent parts in the circuit from being damaged due to instantaneous discharge caused by static electricity accumulation. 8. Increasing design efficiency: The micro-hole technology allows the circuit to be arranged in the inner layer, so that the circuit designer has more design space, so the efficiency of the circuit design can be higher.