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The purpose of this paper is to present the materials and process considerations and solutions that enable the safe use of plugging pastes in high density interconnection (HDI) printed circuit boards (PCBs) designed to operate at higher temperatures.

The paper introduces the concept of microvia plugging and the issues that are important in influencing HDI PCB reliability. Plugging pastes and their properties are discussed along with the various plugging processes that can be used. The advantages and disadvantages of each type of process are compared and contrasted.

The creation of via holes and the filling of these interconnection holes or buried vias and their subsequent copper plating is one of the key processes in HDI technology. In future, the importance of plugging will increase, particularly on account of the growing demand for copper plating and dimensional stability.

The paper highlights the importance of making the correct selection of materials and processing methodologies and details the implications of these choices.

The paper describes the different approaches that can be used for filling microvias and details the issues, advantages and disadvantages of the various approaches. The paper particularly focuses on the special demands on plugging pastes used in higher temperature range applications.

The purpose of this paper is to form high density interconnection (HDI) of backboard for press-fit applications with the pre-curing conditions of conductive paste. The best condition of pre-curing conductive paste should be found to obtain good electrical and physical performance of the conductive paste and avoid the simultaneous curing behavior of prepreg.

A novel structure of backboard was designed by using the connection of conductive paste-filled through holes to connect two multilayers. Pre-curing conditions of conductive paste were investigated to find their effects on resistance, bond strength and volume shrinkage. The reliability of pre-curing conductive paste was also analyzed.

Pre-curing conditions led to a great influence on the resistance, bond strength and volume shrinkage of the conductive paste. The best condition of pre-curing conductive paste was chosen as the low curing temperature of 60°C and a curing time of 30 min. Cured conductive paste exhibited square resistance of 4.205 mΩ/□ and bonding strength of 22.86 N. The as-obtained pre-curing condition could improve the reliability of conductive paste. Pre-curing process of conductive paste at extremely low temperature to interconnect two multilayer structures improved the density interconnection of backboard for press-fit applications.

The use of HDI of backboard could lead to good assembly for high-speed signal transmission of electronic products with press-fitting components. The connection of pre-curing conductive paste for multilayers could have important function for improving the application for communication backboard.

This paper aims to propose a modified full-additive method (MFAM) to fabricate fine copper lines for high density interconnection (HDI) printed circuit boards (PCBs). In addition, the surface of the fine copper lines is treated with a brown oxidation process to obtain good adhesion between the copper and the dielectric resin.

Fine copper lines fabricated by MFAM were observed to evaluate the undercut quality, in comparison to undercut quality of copper lines fabricated by the semi-additive method and the subtractive method. The effect of the thickness of the dry film on the quality of the copper plating was investigated to obtain the regular shape of fine lines. The fine copper lines treated with the brown oxidation process were also examined to generate a coarse surface microstructure to improve the adhesion between the copper and the dielectric resin. The cross section and surface of as-fabricated fine copper lines were characterized using an optical microscope, a scanning electron microscope and an atomic force microscope.

MFAM has the potential to fabricate high-performance fine copper lines for HDI PCBs. Undercut of as-fabricated fine copper lines could be prevented to meet the design requirement of impedance. In addition, fine copper lines exhibit enough adhesive force to laminate with dielectric resin after the brown oxidation process.

MFAM, with the advantages of high efficiency and being a facile process, is developed to fabricate high-quality fine copper lines for industrial HDI PCB manufacture.

To review the challenges confronting the electronics interconnection industry as it transitions into the gigahertz frequency range and to describe novel prospective solutions designed to circumvent the problems by means of alternative interconnection architectures while remaining within the confines of the existing manufacturing infrastructure.

The paper has been written in a manner so as to provide first a brief review of the history of interconnections as background reference, providing access and understanding to a broader readership of the significance of the area of investigation. From there, the paper describes the problems facing electronic circuit manufactures relative to the serious matter of assuring signal integrity of high speed interconnections. It then goes on to describe a general class of prospective solutions, which can be implemented through simple architectural changes in design and manufacture. Finally, the paper describes a prototype system which was fabricated using the concepts and the first‐order findings are provided.

From operation of the prototype system, it was found that the concepts, relative to PCB architectural changes prescribed in the paper are capable of delivering performance levels beyond what is accepted when using traditional interconnection modalities. The 10 Gbps backplane prototype has proved capable of sending a 100 mV peak‐to‐peak signal a distance of 75 cm through a two wire single differential pair which pass through two industry standard connectors. The signal generated has a ∼65 percent margin indicating it could go much further and determining the limits an object of future study. The modulation is standard NRZ. With only two wires there was no cross talk in the system, however, the next stage of investigation will consist of a multi‐device assembly to see what cross talk effect there might be, if any.

The chief value of the paper resides in its disclosure of novel approaches to electronic interconnection involving simple changes in circuit architectural structures which extend the signal performance limits of copper interconnections, well beyond present consensus expectations of industry. Moreover, the paper provides first experimental results of the technology in actual operation as proof of concept.

Imprint patterning is a new circuit formation process that is based on a well‐established technology called microreplication. Microreplication has been used for many years for making a diverse range of products such as compact discs (CDs), roadside reflective signs and even holographic wrapping paper. As is the case with printed circuit boards microreplication is typically practised where the surface features are very small in relation to the length and width of the product. This paper reports details of a new and potentially disruptive technology that draws on a well‐established imprinting process to provide a comparatively low cost and shorter route to the fabrication of high density interconnections and microvias.

To provide a clear picture of the current status of mechanical drilling of printed circuit boards (PCBs).

A review paper detailing the developments of micro‐drill bit and PCB mechanical drilling techniques.

Mechanical drilling will still dominate the PCB hole processing methods. A design method on the basis of theoretical analysis, numerical simulation and experimental verifications is proved as an applicable way to improve the drill bit design efficiency. Newly developed tungsten carbide, novel coating techniques and high‐performance steel‐shank micro‐drill bits are expected. Solutions of micro‐drill bits for high‐density interconnection, IC substrate flexible PCBs, halogen and lead‐free assembly compatible PCBs, as well as 2 mm shank diameter drill bit are worthy of being concerned.

The paper highlights the state‐of‐the‐art techniques of micro‐drill bit manufacturing and novel developed micro‐drill bit. The development direction of micro‐drill bit in the future is concluded.

The purpose of this paper is to introduce a new copper electroplating formula which is able to fill blind microvias (BVHs) and through holes (THs) at one process through a direct current (DC) plating method.

Test boards of printed circuit board (PCB) fragments with BVHs and THs for filling plating are designed. The filling plating is conducted in a DC plating device, and the filling processes and influence factors on filling effect of BVHs and THs are investigated. Dimple depths, surface copper thickness, thermal shock and thermal cycle test are applied to characterize filling effect and reliability. In addition, to overcome thickness, increase of copper on board surface during filling plating of BVHs and THs, a simple process called pattern plating, is put forwarded; a four-layered PCB with surface copper thickness less than 12 μm is successfully produced.

The filling plating with the new copper electroplating formula is potential to replace the conventional filling process of BVHs and THs of PCB and, most importantly, the problem of thickness increase of copper on board surface after filling process is overcome if a pattern plating process is applied.

The dimple depth of BVHs and THs after filling plating is not small enough, though it meets the requirements, and the smallest diameter and largest depth of holes studied are 75 and 200 μm, respectively. Hence, the possibility for filling holes of much more small in diameter and large in depth with the plating formula should be further studied.

The paper introduces a new copper electroplating formula which achieves BVHs and THs filling at one process through a DC plating method. It overall reduces production processes and improved reliability of products resulting in production cost saving and production efficiency improvement.

The purpose of this paper is to optimize experimental parameters and gain further insights into the plating process in the fabrication of high-density interconnections of printed circuit boards (PCBs) by the rotating disc electrode (RDE) model. Via metallization by copper electrodeposition for interconnection of PCBs has become increasingly important. In this metallization technique, copper is directly filled into the vias using special additives. To investigate electrochemical reaction mechanisms of electrodeposition in aqueous solutions, using experiments on an RDE is common practice.

An electrochemical model is presented to describe the kinetics of copper electrodeposition on an RDE, which builds a bridge between the theoretical and experimental study for non-uniform copper electrodeposition in PCB manufacturing. Comsol Multiphysics, a multiphysics simulation platform, is invited to modeling flow field and potential distribution based on a two-dimensional (2D) axisymmetric physical modeling. The flow pattern in the electrolyte is determined by the 2D Navier–Stokes equations. Primary, secondary and tertiary current distributions are performed by the finite element method of multiphysics coupling.

The ion concentration gradient near the cathode and the thickness of the diffusion layer under different rotating velocities are achieved by the finite element method of multiphysics coupling. The calculated concentration and boundary layer thicknesses agree well with those from the theoretical Levich equation. The effect of fluid flow on the current distribution over the electrode surface is also investigated in this model. The results reveal the impact of flow parameters on the current density distribution and thickness of plating layer, which are most concerned in the production of PCBs.

By RDE electrochemical model, we build a bridge between the theoretical and experimental study for control of uniformity of plating layer by concentration boundary layer in PCB manufacturing. By means of a multiphysics coupling platform, we can accurately analyze and forecast the characteristic of the entire electrochemical system. These results reveal theoretical connections of current density distribution and plating thickness, with controlled parameters in the plating process to further help us comprehensively understand the mechanism of copper electrodeposition.

Printed circut boards (PCBs) have diminished in size and, simultaneously, their circuit densities have increased. Conventional multi‐layered PCBs have a limitation to higher packaging densities. This paper introduces a new copper electroplating formula that is able to fill vias and through holes simultaneously and is used in a DC plating method, in which the copper thickness deposited on the board surface is relatively very thin after the electroplating is completed.