HDI circuit board

The HDI circuit board is defined as a Microvia having a pore size of 6 mil (0.15 mm) or less, a hole having a Hole Pad of 0.25 mm or less, a contact density of 130 dots per square inch or more, and a wiring density The At 117 inches / square inch, the line width / spacing of 3mil / 3mil below the printed circuit board Generally speaking, HDI circuit board has the following advantages:

1. Can reduce the cost of PCB: When the PCB density increases more than eight layers, to HDI to manufacture, the cost will be more complex than the traditional process of pressing too low.

2. Increase the line density: the traditional circuit board and parts of the interconnection, must be led around the QFP line and through-hole conductor as a connection (fan-in and fan-out), so these lines need to occupy some space and micropores Technology can be connected to the wiring required to hide the next layer, the different levels of bonding between the pad and the lead, then the blind hole within the pad directly connected, without fan-fan and fan-out wiring. So the outer board can be placed on some pad (such as micro-BGA or CSP small ball welding) to undertake more parts, can increase the density of the circuit board. At present, many high-performance small wireless phone phone board, is the use of this new stack and wiring method.

3. is conducive to the use of advanced construction technology: the traditional traditional drilling technology due to pad size (through hole) and mechanical drilling problems, and can not meet the needs of small parts of the new generation of fine lines and the use of micro-technology process progress , Designers can design the latest high-density IC component technology, such as Array package, CSP and DCA (Direct Chip Attach), into the system.

4. Have better electrical performance and signal correctness: the use of micro-hole interconnect in addition to reducing the reflection of the signal and the line between the string interference, and the circuit board design can increase more space, due to microporous The physical structure of the hole is small and short, so the effect of inductance and capacitance can be reduced, and the switching noise at the time of signal transmission can be reduced.

5. Better reliability: microporous due to a thin thickness and 1: 1 aspect ratio, the reliability of the signal transmission than the average through-hole is higher.

6. Improve thermal properties: HDI board insulation dielectric material has a higher glass transition temperature (Tg), and therefore have better thermal properties.

(RFI / EMI / ESD): Microporous technology allows circuit board designers to shorten the distance between the ground plane and the signal layer to reduce RF interference and electromagnetic interference; on the other hand, the RFI / EMI Increase the number of ground lines, to avoid parts of the circuit due to static electricity caused by instantaneous discharge, and damage.

8. Increased design efficiency: Microporous technology allows the line to be arranged in the inner layer, so that the line designer has more design space, so the efficiency of the circuit design can be higher.