Prepregs used in the PCB industry possess various properties and need to be handled with care to maintain
identical chemo -rheological properties to yield dimensionally stable laminates. A prepreg is a viscoelastic polymeric material which losses some portion of energy exerted on it. The characteristic viscoelasticity property depends on the chemical reaction and rheological flow path. To heat the prepreg more uniformly,a new method is invented,utilizing a metal separator as an electrical heating medium (Heated Electrical Separator -HES). The HES technology has been tested to demonstrate the improvement in temperature uniformity among the boards in daylight. A mathematical squeeze flow model is used to stress the consequences of different heating histories on the pressed
laminate thickness.

Polyimides have proven their performance in electronic applications demanding high strength,increased durability,
broader temperature ranges and exceptional chemical resistance. They serve as the material of choice for fabricating
flex circuitry due to their excellent properties and demonstrated capabilities. Typical polyimides require the use of
an adhesive to assemble multilayer circuits,which results in additional material thickness for the overall package.
Several concerns related to the adhesives currently used involve CTE mismatch,wrinkling,voids and delamination
of the layers that can ultimately lead to circuit failure. The recent trend is toward adhesiveless materials; reducing
the total package thickness without compromising the performance,capacity or cost of the final product.
One material,which has been investigated in an effort to meet the demands of the electronics industry,is an
advanced polyimide developed by researchers at NASA Langley Research Center. SI (Soluble Imide) is a
thermoplastic that extends the possibilities for polyimides in flex circuits. SI can be used as a substrate material by
laminating or casting directly onto metal foil such as copper or aluminum yet is versatile enough to be used as the
adhesive in fabricating flex circuits thereby producing an ultra-thin adhesiveless,monolithic flex circuit. Eliminating
the adhesive results in a reduction in materials and processing costs,lighter end weight circuits,increased flexibility,
and circuits with smaller z-axis expansion.

??Machine Technology designed for the manufacture of Ultra Fine Line product
??Machine design provides clean production environment
??Latest State of the Art,Horizontal Wet Processing Equipment
??Intelligent Machines with high levels of automation,self cleaning
??Reliable process control and dosing systems that can maintain demanding production tolerances
??Bar-coded panels automatically adjust machines processing parameters
??Reel to Reel production for thin material
??A totally integrated production system
It’s all the numerous single details which when combined,in the end,make a highly capable and effective
production environment.

With the printed circuit board becoming increasingly complex,there is an ever-growing need to implement
manufacturing standards that ensure high productivity at even higher yields. Factors such as operator error and
incorrect data collection make producing such boards an exercise in frustration. If a company is going to be
successful in the future,it must look to implement a total system of Supervisory Control And Data Acquisition as a
means of success. Since this industry is one of the last high-tech industries to embrace SCADA,this paper will give
attendees a better understanding of why such a discipline is a necessity.

A new thermosetting resin system with modified cyanate ester resins having a loose cross-linked structure and
alloyed with polymers was developed to provide low dielectric constant (Dk) and low dissipation factor (Df)
materials for high-frequency PCBs. The laminates with this resin and glass fabrics demonstrated low transmission
losses at high frequencies up to 30 GHz. Those with inorganic filled resin and glass fabrics were almost comparable
in Dk and Df to the conventional PTFE laminates. These new materials have a high Tg,low moisture absorption,
and excellent mechanical performance. They showed the same processability and reliability as the conventional FR-
4 materials. They will be suited to the multilayer PCBs for high-speed communications as well as the low loss
circuit boards for telecommunications.

Highs Density Interconnects (HDI) printed circuits are now being designed in ever increasing quantities for very high speed applications. The challenge of opto-electronics and integration of photonics down onto the printed circuit
has started to take off. In the next seven years,expectations are that photonic PCBs will grow to a $2.5 billion dollar
industry.
This paper looks at the issues,materials and current processes being researched to create this integrated Opto-
Electronic Circuit Board by European,Japanese and N. American organizations.

There is a growing need in today’s electronic market for high performance Printed Circuit Boards (PCBs) with highspeed signals and enhanced performance. However,they must maintain signal integrity,PCB reliability,quality,and meet the overall thickness constraints of the application. In order to meet these demands,Microvia Technology is utilized to increase design real estate (routing density),improve signal integrity,reduce overall thickness,and enhance PCB reliability. Therefore,Laser Drilling Technology for microvias is fast becoming standard equipment for PCB fabricators in North America. This paper will discuss YAG and YAG/C02 combination laser drilling systems utilized in North America today,compare laser drilling efficiency of microvia materials,and the cost to drill microvias in high performance PCBs.

There is a contingent in the industry that feels reinforced substrates are needed to meet the performance
requirements of HDI microvia technology. Concerns that non-reinforced resin coated foils,or non-woven substrates,
may not provide the thickness control and predictability of movement and reliability needed to meet the next
generation of infrastructure board designs,which must include microvias. Conventional woven glass offerings used
for prepregs which have been fabricated using laser drilling technologies have yielded inferior hole wall quality and
require higher pulse counts making them an undesirable alternative to some.
Development of a laser drillable glass fabric has given new hope to conventional prepregs,offering a better fit to all
attributes desired in materials for HDI microvia applications. Clean hole quality at fewer pulses than conventional
glass fabric,better dimensional performance,dielectric yield control,reduced cracking,ease of handling and storage
and availability make the new generation of laser drillable prepregs an attractive alternative where supported
substrates are desired.
This paper will discuss the attributes and short falls of laser drillable prepregs in comparison to other material types
commonly used in HDI applications.

The combination of high speed and accuracy laser beam deflection,the know-how on wet chemical processes for
Printed Circuit Boards (PCB’s),as well as CAD/CAM implementation for Laser direct Structuring (LS) of PCB’s
together with machine development and construction know-how,resulted in a total laser technology with a
dedicated system (Figure 1),that offers an innovative alternative for the manufacturing of High Density
Interconnection (HDI) technology.
The LS process can easily be integrated into standard PCB production lines,what is proven at a European PCB
manufacturing site. The LS process uses a thin immersion Tin (Sn) as etch resist that is ablated by a focused laser
beam. The laser beam contourizes the circuitry tracks and pads.
The movement of the laser beam is controlled by a high-speed controller,based on electronic CAD-layout data.
This allows to achieve 50 µm space – line structures –and even smaller- without the need for clean room facilities,
with acceptable yields (>70 –80%) and acceptable processing time.
Furthermore,the system has a highly flexible modular construction; a system set-up with a 532 nm (green) or 355
nm wavelength laser proofs to be an excellent structuring as well as µ-via drilling system and this from quality but
also performance view point.

The electronics market demands for smaller,faster,more reliable and less costly products continues to fuel major
changes in printed wiring board designs. Higher layer counts,increasing circuit densities and HDI technologies have
forced the PWB manufacturing industry to find new and unique methods of producing the sub 3mil lines and spaces
required to meet today’s design challenges. Until recently,Laser Direct Imaging (LDI) had been a viable,but cost
prohibitive method of creating ultra-fine line circuitry patterns. Today,new advancements in LDI equipment,laser
technology as well as the introduction of specialized photoresists have allowed LDI to emerge as a production viable
process. Continuing to derail the cost drivers associated with laser direct imaging will further enable LDI processing
to play a leading role in PWB manufacturing today and into the future.