Using conventional PWB copper electroplating techniques (DC bath chemistry with air agitation),non-uniform deposition inside blind via features may arise when the vias have diameters less than 6 mils and aspect ratios greater than one. These observations result from two main causes: unfavorable solution hydrodynamics and the presence of air bubbles. Ultrasonic agitation (UA),well known for cleaning purposes,can provide a strong local agitation that "refreshes" the plating solution inside holes together with punching small trapped air bubbles. It has been demonstrated that UA greatly enhances the throwing power inside small blind via features. It must be pointed out that low UA power densities were used (2 to 8 W.gal-1). The frequency was 40 kHz and air was bubbled during plating. Using a conventional DC plating solution at 15 ASF,throwing power was improved on average by 35.9 %
for vias having a diameter of 6 mils and aspect ratio between 1.25 and 1.5. A more drastic 74.6 % throwing power improvement was noted for 4 mils blind vias having an aspect ratio of 1.9 and 2.4. Through ductility measurements,it has been also demonstrated that plated through hole reliability was improved using mild UA.

Among the many advantages of Periodical Pulse Reverse (PPR) technology,improvement in throwing power and plating thickness uniformity are the most obvious. Traditionally,the biggest drawback of the technology is that it plates well in one size hole but poorly in others,when there are several sizes of holes within a board or different
current density areas. Modulated Current Technology Controller (McTc) is a new technology in PPR,which generates modulated complex waves to overcome such drawbacks of the current technologies. High aspect ratio holes of various sizes on a board and irregularly distributed circuitry in pattern plating boards may all achieve more uniform plated thickness and throwing power using this technology.

Copper plating in the printed circuit board industry has traditionally used soluble copper anodes in a vertical configuration. Newer,high speed,horizontal plating lines utilize insoluble anodes which provide better current distribution and throwing power,higher operating current density,fixed and closer anode/cathode spacing,and lower copper cost. This paper presents results of a direct comparison between soluble and insoluble anodes on the plating performance on various types of printed circuit boards. This includes ductility,copper finish,and operating current density versus throwing power. Addition agent consumption at insoluble anodes and copper ion replenishment,as required for insoluble anodes,are discussed.

This paper presents a method both to enhance the yield of embedded resistor processes and to print embedded resistors using drop-on-demand ink-jet device capable of dispensing a precise volume of intrinsically conductive polymers (ICPs) onto plated or screen printed resistors. By controlling the volume of ICPs,and in turn its thickness,
the resistance per square can be controlled and brought to the PWB industry tolerance. This method can be used as complementary to laser trimming method to enhance the overall yield of embedded passives processes.

It is not often understood that when electrical signals travel along a wire or trace --- they reflect. Always! We intuitively understand that when we send audio waves across a room,a field or a canyon,they reflect. We call those “echoes.” Echoes can happen in a great many places,even in small rooms. But we have a harder time understanding that electrical signals reflect also. We call that,well,reflections!

If in designing your next product you are interested in cost reduction,reliability improvement,and increased electrical performance,then you should be considering using laser-drilled vias. Not only high end product design gains advantages,but commercial products should consider using laser-drilled vias. Discussions about cost,reliability and performance are presented.

Several of the major OEMs are introducing a variety of thermal reliability requirements for printed wiring boards as a result of increasing demands during assembly. These increasing demands manifest themselves as multiple soldering operations and/or higher soldering temperatures using lead free alloys. This paper is based on a correlation study between reliability testing and thermal shock testing using a common set of multilayer coupons produced in the same pwb fabrication shop in real time. Reliability testing involves the Interconnect Stress (IST) test and thermal shock data includes both TMA (T260) and Multiple Shock Testing (6X solder float). There is also discussion concerning the importance of reviewing the TMA scan when interpreting thermal performance of a multilayer coupon in addition to considering the compatibility of the fabrication process with the material being tested.

Reliability assessment of Printed Wiring Boards and Assemblies using High Humidity at elevated temperatures has been done for a number of years. Many companies,including the IPC have published test requirements for products at high humidity at elevated temperatures. We currently perform testing to at least 10 different variations of these types of tests. In addition to variations in Temperature and Humidity,these tests also vary in whether a forcing potential is used during the test cycle. When a forcing voltage is used there are a variety of voltages specified. There are also differences in test voltage and whether the test voltage is applied in the same direction as the forcing voltage. This paper will describe the varying test methods used to conduct these environmental tests along with detailing the differences between them. It will highlight the different test patterns used and the benefits and limitations they represent. It will also encompass issues concerning test sample preparation,wiring,and placement within the test chamber that are not always addressed in the test method procedures.

A uniform transmission line is described electrically by a characteristic impedance and a time delay. From the length of the line and the time delay,the effective dielectric constant can be extracted. Two instruments are commonly used to measure these properties,a time domain reflectometer (TDR) and a vector network analyzer (VNA). In this paper,these techniques are reviewed. We show that an important factor influencing the quality of the measurements is the way the structure is probed. When using microprobes,the characteristic impedance and effective dielectric constant can be measured to within 1% accuracy. A collection of tips and tricks to improve the measurement accuracy are presented. Finally,the ability to accurately measure the dissipation factor of any laminate material up to 10 GHz,
with a VNA,is reviewed.

Automation,change and complexity have become the normal working environment in the PCB market. With this change has come the realization that high tech manufacturing,technological innovation and the fast paced world of the Electronics Interconnection Industry are intimately connected to rapid learning. In fact the very survival of
companies involved in the design and fabrication of PCB’s,their competitiveness,their ability to innovate and remain cost effective is directly linked to the speed and quality at which technical information is assimilated and applied by their workforces.