<p>Originally developed for DRAM memory , the silicon structure has allowed Toshiba to place the NOR cells much closer together than has previously been possible. This leads to better performance, lower power consumption and lower noise operation while allowing significant reductions in die size.</p>

However, there are different concerns that must be dealt with by proponents of SIP-controlled networks.

Two issues that must be considered by the board fabricator, assembly house and the OEM have historically troubled Thermount, despite its many advantages. First is moisture uptake, in that products based on Thermount absorb more moisture than do standard glass-epoxies and therefore may require some baking or desiccation prior to lamination and solder reflow. The development of second generation ThermountRT products with lower water absorption mitigates this issue somewhat, but it remains a concern especially in high-humidity areas.

The second area of concern for Thermount products has been low copper peel values due to the inherently low cohesive strength of the Thermount product. One ounce copper peel values at or under 5 lb/in were common with early generation Thermount products, which resulted in a mixed reception for the material in applications such as hand held phones, PDAs and laptop computers which must survive a variety of drop impact tests. In the mind of many OEM designers that low peel value is a drop dead” issue in choosing a material for HDI designs.

RNC55H3322FSRE7_Vishay Dale_Through Hole Resistors

Newer generation Thermount-based products such as Arlon's 55ST have attempted to overcome the low peel problem by forming an interpenetrating polymer network (IPN) between the Thermount and the resin system itself, permitting 1 ounce peels as high as 10 pounds/inch-double that of the previous generation of products-and half ounce peels (in foil lamination applications) over 7 pounds/inch. Progress is also being made in the area of water absorption, but there is still need to be careful with drying of these materials.

3. Flat glass” (and better lasers) – New to the foil lamination arena is the use of so-called flat glass,” which is special fiberglass fabric that lies very flat and is easier to lase cleanly than traditional glass weaves. The idea here is that a premium” glass epoxy prepreg can possibly be made to do the job now being done by RCC or nonwoven aramid products. The cost performance of these new glass materials is still in the process of being evaluated.

On another front, although not a subject being detailed in this article, improving laser technology may well help this and other materials achieve microvias faster and more cleanly-both of which are still issues with trying to form quality microvias in glass fiber based products.

RNC55H3322FSRE7_Vishay Dale_Through Hole Resistors

Back to the future

For the future, a wider variety of materials and designs will take advantage of foil lamination for surface microvia formation. Applications requiring higher frequencies will need materials that can be laser-drilled, yet which have low dielectric constant and loss characteristics for handling microwave and FR signals. Large optical backplanes will utilize materials that can act as light ducts at the board surface; while this is not foil lamination as we currently know it, the newer technology will add a level of complexity to the interconnection between surface copper foil and the multilayer board beneath. A variety of thermoplastic film materials may well be used in surface microvia applications-materials such as liquid crystal polymers (LCP) are already being considered for related applications.

RNC55H3322FSRE7_Vishay Dale_Through Hole Resistors

As we go forward, the challenge for the board designer and fabricator will be to integrate some of these newer concepts in surface microvia materials and cope at the same time with the fact that they don't all process just like FR-4.” However, it is exactly these types of emerging technologies that will open new vistas for board performance, continued size reduction and density increase.

Chet Guiles is director of new business development for Arlon, Materials for Electronics Division. He joined Arlon in 1979 and prior to assuming his current technical marketing responsibilities, held positions as technical director and product manager, as well as various assignments in process engineering, technical service, cost accounting and quality assurance. Guiles has a B.A. in chemistry (1972) from the University of New Haven, West Haven, CT, and is the author of Everything You Ever Wanted to Know About Laminates…But Were Afraid to Ask” and numerous articles and papers on the subject of high performance laminate materials. Additional information, including the text of Everything You Ever Wanted to Know About Laminates…” can be found at www.arlonmed.com.

The first version is aimed at cable modems using the Docsis and EuroDocsis standards which use 6 and 8MHz bands, respectively.

The UniSite-xpi Programming System is the latest in Data I/O's line of true universal device programmers.

It supports virtually every programmable device on the market regardless of technology or package including anti-fuse, high capacity memory devices, Flash, CPLDs, FPGAs, microcontrollers, as well as older device architectures such as bi-polar and ECL. New high-speed parallel interface enhances the performance of this industry standard product.

For further information contact Data I/O.


Both AudioCodes and Octave Communications (Nashua, NH — 603-459-5200, www.octavecomm.com), experts in next-generation, reservation-less audio conferencing, recently announced a joint development project on a next generation IP conferencing product. AudioCodes' TrunkPack TP-610 will be integrated with the Octave OCI 1000 conferencing platform that supports various telephony applications and international networking protocols, including E1, T1, and ISDN PRI. The OCI 1000 platform enables customers to combine PSTN and VoIP functionality in the same footprint. The OCI 1000 allows an impressive 1344 ports in one chassis.

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