Site: Nitto Denko Corporation
61-7, Aza-Sasadani, Yamadera-cho
Kusatsu
Shiga 525, Japan

Date Visited: October 6, 1993

Report Author: G. Harman

ATTENDEES

JTEC:

W. Boulton
G. Harman
G. Meieran
M. Pecht
D. Shelton

HOSTS:

M. Takemoto

Y. Takashima

M. Sano

S. Omori

H. Tabada

T. Mitarai

M. Kaneto

BACKGROUND

Nitto Denko is a diversified materials company with headquarters in Osaka. Nitto Denko's philosophy is to listen to the customers who are on the leading edge of technology and to develop or improve products for their use.

The company was founded in 1918 to produce electrical insulating materials in Japan. Each product center has its own development group and profit center and issues its own financial report. Nitto Denko is an independent company, not part of any keiretsu. About 30% of its business is semiconductor- and electronics-related. Other areas include industrial products, packaging products, engineering plastics, medical products and membrane products. Nitto Denko is a major plastic molding-compound supplier for semiconductor chip encapsulation. Our hosts also indicated that Nitto is the major producer of polarizing films (used in flat panel displays) and low friction rings (used in floppy disks). The company's newest venture is to produce cultured (fermented) ginseng soft drinks to help improve its profit margin. Nitto Denko has manufacturing plants for various products located all over the world, including three in the United States that will be expanding soon as the firm moves more production off shore.

Nitto Denko's philosophy emphasizes that it listens to its customers - a lesson that many American companies could learn. It has a standing committee to help solve applications problems of companies using its products. Planning for future growth is exceptional. Company personnel have outlined the entire semiconductor assembly and packaging process and would like to develop products that will contribute to or simplify each step. A diagram showing this approach is given in Figure Nitto.1. A further example of Nitto's exceptional planning is its development and fitting of future products into the U.S. SIA roadmap for semiconductor development by the year 2000. Our hosts at Nitto Denko stated that they have a department of "Research on New Basic Technology," but nothing we saw was identified as coming from that. In fact, when asked how many Ph.D.s they have in this particular plant, their response was "only one." Before a recent reorganization they had four.


Figure Nitto.1. Nitto's technical development plan for semiconductor related materials.

Nitto's Kameyama plant is highly goal-oriented. It has a product line that primarily consists of adhesives and packaging and encapsulation materials. The company then looks for ways to apply these products and expertise to the field of electronics materials. The JTEC team discerned no fancy gear or advanced research projects; just a strict "improve the product and look for new areas to apply products," no-nonsense approach. The company is quite creative in looking for new applications, but in the electronics areas, it is not trying to expand its product line into ceramic packaging. It is the company's understanding of the characteristics of plastic materials that separates it from its competitors. Nitto appears to be a world leader in this area.

Finances

Nitto had net sales of $2.187 billion with a net income of $34.3 million in 1993. This compared with a net income of $55.7 million in 1992, and $71.3 million in 1988. The sharp decline in 1993 resulted from the increased value of the yen, coupled with downward cost pressure from its Japanese customers. It is planning to expand production overseas to help overcome the effects of the increasing value of the yen.

The biggest problem facing Nitto is the flat sales volume for plastic molding compounds. The volume of molded plastic packages continues to increase, but the thinner package dimensions, e.g., small outline devices, may be only 0.5 mm thick, and improved mold design leading to reduced loss of plastic during the molding operation has led to flat sales. It seems that both of these trends will continue in the foreseeable future. However, it is not obvious what can be done to improve this situation. Nitto has been a leader in developing low-stress molding compounds as well as in low alpha particle filler materials, and it is well positioned to maintain leadership in these various technical areas, as well as in the new products mentioned below. Company officials hope that increased overseas production will overcome the flat sales and profits in the older product areas.

Specific Products

Nitto is developing a number of new products based on its core technologies. One such product is a new die attach material for application to the whole wafer called "Elep Mount." This is a conductive epoxy film applied to the backside of the wafer before sawing. This application can save several assembly steps and thus time and money. (Note: This is an old idea originating in the '70s at Fairchild. Early in the '80s, such films were unsuccessfully marketed by Stauffer Chemical, a U.S. company, which sold that division to Ablestick. The film is apparently not marketed now. Amicon also tried to market a conductive epoxy screened-on-wafer variation of the system in about 1985. Both had technical problems relating to water pickup in the uncured resin during sawing, even if the wafer is not sawed through, which assembly people prefer to do. A water-repellent uncured epoxy film with new specialized equipment, with IC manufacturing cost pressures, may make it successful for Nitto.)

Other semiconductor-related products were discussed. We requested information on a product called ASMAT. This is being developed by Nitto for an ARPA contractor (U.S.) who is planning to use it as area-array contacts for whole-wafer test and burn-in, to obtain known-good-die. The contacts are hemispherical bumps, precisely electroplated (and/or etched) 48 microns in diameter on large two-metal layers of polyimide films. Nitto has a tough job ahead to cover all of the obvious problems inherent in placing a contact-covered polymer thin film on hundreds/thousands of bond pads in a wafer, e.g., no metallurgical interaction with the bond pad is permitted at burn-in times and temperatures, and the film contacts must be position-stable at all times and temperatures. Also, the contact resistance varies with applied force, so each one of thousands may require its own, or at least regional separate spring loading. Nitto is considering plating the bumps with nickel, gold, rhodium, osmium, etc. It expected to publish a full paper on ASMAT at the ISHM symposium held in November 1993.

Other products in development included improved molding compound adhesion to palladium plated leadframes, high-thermal-conductivity molding compounds for power devices, and others that need lower thermal resistances. Ideally, these materials could be developed to replace ceramic packages. Nitto is also working on recyclable molding compounds (presumably thermoplastics) and low-viscosity compounds intended to go under flip chips (a process developed by IBM). Nitto is also developing mold compound pellets that are dust-free for use in the future (class 100) clean-room assembly and packaging areas. Nitto is also studying trapping agents that can slow the migration of bromine ions (fire retardants) in molding compounds and thus increase gold wire bond reliability. It is developing compounds that are stronger, have greater leadframe adhesion, and have lower moisture absorption, for use in TSOPs (thin small-outlined packages). In addition, Nitto is developing materials that require no post mold cure (currently such cure takes five to six hours at 175 degrees C). It is using the Cornell University software for modeling its thermosetting plastics. Also being developed are lines of adhesive contacts and adhesive tapes for die attach, TAB assembly, flexible mounting for chip carriers, etc. It seems to have a well thought out strategy for applying its specific technologies to the entire range of assembly and packaging needs of the industry.

PLANT TOUR

The Nitto Denko plant and much of the equipment was not new, but certainly appeared to be adequate for the job. The failure analysis and other materials analysis lab facilities appeared adequate, but by no means grandiose. There were all the important analytical and environment test facilities needed for evaluation of plastic packaged devices: IR microscope, SEM, radiography, EDX and WDX, TMA and TAG, pressure cookers, thermal cycle and thermal shock, etc. There were no super advanced capabilities such as advanced surface analysis (Auger, STEM, ESCA, etc.), but the company seems to have access to those capabilities if needed. Our main impression of the analytical facilities is that they are extensively used. Work was going on in most of these facilities (which are located in one large room.). Each piece of equipment was clearly labeled in English, apparently for the benefit of the many visitors who come to the facility.

A large area is devoted to lead frame plastic molding equipment for running the many experiments necessary to develop new molding compounds. These experiments are designed by finite-element-modeling of the mold compound during molding to minimize wire-sweep and air bubbles. (Nitto may use some of the Cornell software imbedded in its own). There was considerable QA equipment available for testing the molding compounds (gelling time, rheology tests, spiral flow testing, etc.). We saw several examples of QA processes during our tour.

The plant was typical of a chemical manufacturer rather than an electronic (clean-room environment) manufacturer. This was especially evident in the areas where the mold compound was formulated and pelletized. However, it should be emphasized that there was sufficient cleanliness for the products, and if more is needed, it will be supplied. The level of automation in the preparation of molding compound is not particularly high, but adequate for the job.


Published: February 1995; WTEC Hyper-Librarian