Printed Wiring Boards Technologies

Fukuoka, Yoshitaka, New High Density Printed Wiring Board Technology Named B2it, JIPC Proceeding, Vol. 11, No. 7, November 1996, pp. 475-478. 

J. Fjelstad, Printed wiring board technology current capabilities and limitations, in Electronics Materials Handbook (C. A. Dostal, ed.), ASM Int., Materials Park OH, 1989, pp. 507-512 and references therein. 

Electronic Materials. Applications of photopolymer technology to electronic products is probably one of the largest imaging categories in terms of sales and total number of patents and publications. A wide variety of products have been developed for the production of printed wiring boards (PWB) and the manufacture of integrated circuits (IC). 

This technology is currently commercially available. Polylonix Separation Technologies, Inc., offers polymer filtration for the treatment of metal-contaminated wastewaters from the electroplating and printed wire board industries. 

With the conventional technology, ICs are mounted individually in plastic or ceramic single-chip packages (SCPs), such as dual-in-line packages (DIPs) or chip carriers, and the SCPs are interconnected on printed wiring boards (PWBs). The number of pins on SCPs has increased significantly, and line widths on PWBs, like IC feature sizes, have followed a historical downward trend (2). However, the basic SCP-on-PWB approach has remained predominant. 

Much of the newer technology is driven by the needs for low dielectric constant and controlled impedance, a low dielectric constant being an advantage of foamed materials. Clearly, dimensional stability is becoming increasingly important for printed wiring boards. 

W.S. Fujitsubo, Lithography impact on printed wiring boards, Solid State Technol. 29(6), 161 (1986) A. Reiser, Photoactive Polymers The Science and Technology of Resists, p. 165, John Wiley Sons, Hoboken, NJ (1989). 

Other Markets. PPTA fibers are used to form nonwoven sheet reinforcements that are used as substrate for printed wiring boards where low thermal expansion or the ability to use laser drilling technology are important. Other applications for aramid fibers include cement reinforcement, the engineered liunber... 

Since the invention of printed wiring technology by Dr. Paul Eisner in 1936, several methods and processes have been developed for manufacturing printed wiring board (PWBs) of various types. Most of these have not changed significantly over the years however, some specific trends continue to exert major influences on the types of PWBs required and the processes that create them ... 

Although the main bare board testing technology is electrical, it is important to consider that nonelectricai methods are also important in the acceptance or rejection of bare printed wiring boards (PWBs).This chapter therefore includes detailed descriptions of both electrical and nonelectrical testing methods. 

Lish, E. E, Laser Attachment of Surface Mounted Components to Printed Wiring Boards, paper presented at the Sixth Annual Soldering Technology Seminar, Naval Weapons Center, China Lakes, CA, February 1982. 

FIGURE 59.1 First-, second-, and third-level interconnects defined, employing a flip-chip assembly as an exampla The first-level interconnect is the primary coimection between the silicon die and the package substrata In this example, the coimection is created by the solder bumps between the die and the package. The second-level interconnect in this example is the next level of connection between the package substrate and the module substrate. The third-level interconnect in this example is created when the solder balls on the bottom side of the module substrate are attached via surface-moimt technology (SMT) to the printed wiring board (PWB). 

One alternative to the electroless process utilizes conductive polymers. Polymer thick film (PTF) technology is a method of screening polymer conductors, resistors, dielectrics, and protective coatings on a substrate or printed wire board to create basic circuitry or interconnections. The use of screened-on conductive films in place of the formaldehyde-containing electroless copper process is gaining acceptance in Asia (more so than in the United States at this time). 

In 1988, the National Bureau of Standards [now the National Institute of Standards and Technology (NIST)] ran room combustion tests comparing flame retardant with non-flame retardant plastics used in printed wiring boards, television set and business machine enclosures, cables, and upholstered furniture. The results showed that flame retardant materials allow more than a 15-fold longer escape time, 75% less heat release, significantly less smoke, and a lower concentration of toxic gases. Fire retardants decrease toxicity in fires. The effect is due to a decrease in the amount of burning material. ... 

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