Interconnections in Multilayer PCBs Based on Microvias Metallized by Magnetron Sputtering Deposition
The high advanced miniaturization of electronic components determines designers and producers of PCBs (printed circuit boards) to search the new constructions and technologies of HDI (high density interconnect) PCBs manufacturing. The researches are concentrated on the problems of miniaturization of PCBs interconnections. Many possibilities in this area are created by using microvia technology. The microvias can be made by using several techniques of drilling, but the great problem in this aspect is connected with possibilities of proper and repeatable metallization of microvias. Wide practical techniques of metallization allow to properly metallize of blind microvias which aspect ratio (deep/diameter of microvia) is about 1 or less. In the paper we propose the use of the magnetron sputtering deposition of copper to metallize the high aspect ratio blind microvias. During tests the use of magnetron self-sustaining mode also was investigated. This special mode allow to deposit of thin and very clear (without labour gas particles) electro-conductive layers which can be grown in electroplating processes
Numerical Modeling of Electrical Resistance of Interconnections in High-Tech Multilayer PCBs Manufactured by Magnetron Sputtering Deposition of Copper
In the paper, authors focus on application of numerical simulation methods along with the experimental measurements to access the electrical resistance of interconnections in PCB (printed circuit board). The comparison of experimental and numerical results allow to define the design rules of interconnection properties and specification of interconnection and technology details depending on the selected application. Additionally, it is believed to allow course prediction of deposition process of conductive layer on via walls, without necessity of performing costly and time consuming experiments. In the paper authors present results and investigations which should lead to manufacture interconnections with aspect ratio (relation of via deep to via diameter) higher than 1, and diameter of via in the range of 25 to 150 mum.
Low pressure magnetron sputtering and selfsputtering discharges
Abstract Operation of three magnetrons with diameters 100–160 mm have been measured at pressures below 0.1 Pa. At low and medium discharge power density ≤ 10W/cm 2 , stable discharge has been achieved down to the Ar pressure range (1.1–2) × 10 −2 Pa. Discharge characteristics of selfsputtering discharges have been measured in the range of target power densities 2 W/cm 2 to 100 W/cm 2 . Selfsputtering of Cu was achieved at power density 57 W/cm 2 . Selfsputtering was observed on other five target materials: Ag, Pb, Cd, brass and on AI bronze.