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Appendix E Packaging Technologies in Japan This appendix covers the current use of various packaging meth- ods in Japan for high-, medium-, and low-lead counts, and presents Japanese estimates for the 1990 time frame. The Japanese are ei- ther using or developing four forms of packaging and interconnect technologies: . tape-automated bonding (TAB); flip chip; elastomeric; and ~ film on frame. Packaging and interconnect have received a great deal of atten- tion in recent years in Japan, with impressive results. Table E.1 summarizes the progress made by individual Japanese companies. TAB is used today in Japan predominantly for watches, cal- culators, video games, and some high-speed computer applications (e.g., NEC's SX-2~. There is evidence that the seven or eight major Japanese semiconductor manufacturers are very interested in TAB for plastic flat packages, without the conventional metal leadframe. There is also interest in using TAB with gate array components of moderate lead count. A leading Japanese packaging technologist published a projection in 1985 that estimated that TAB would rep- resent about 15 percent of the market by 1990. This 15 percent was broken down as follows: 261

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262 APPENDIX E TABLE E.1 Pin Counts of Gate Arrays and Rent's Rule Company Gate Number Rent's Count of Pins Rule Fujitsu Hitachi NEC Toshiba OKI NS 200 400 700 1000 1500 3000 1270 3900 2500 2112 3192 2100 4800 6000 34 46 62 78 94 108 80 68 100 78 130 112 107 154 2.41 2.30 2.34 2.47 2.43 2.00 2.20 1.10 2.00 1.70 2.30 2.40 1.50 2.00 SOURCE: Data from Don Brown and Associates. 6 percent for calculators; 4 percent for smart cards with LSIs; ~ 3 percent single-chip plastic molded flat packages with small lead ( 120 pins) used instead of conventional lead- frame/wire; 0.5 percent high-speed computer modules; 0.5 percent SOS multichip assemblies; and ~ 1 percent for watches and games. At least 14 Japanese companies have TAB and flip chip capabil- ity. The TAB applications range from watches and thin calculators to logic modules, although, with the exception of NEC, most TAB logic modules are just coming out of the laboratories. Flip chip applications are in logic and memory. The new ceramic substrate materials under investigation by sev- eral Japanese companies offer a variety of properties and improve- ments that may meet future packaging needs. They offer higher thermal conductivity (silicon carbide (SIC) and aluminum nitride (AIN)) ~.nCt lower dielectric constants. AIN's strengths are in its Tow- dielectric constant and relative low cost (according to Toshiba, in vol- ume it will be slightly higher than alumina). These strengths will al- Tow A1N to be used in many high-power, medium-speed applications. Lastly, the development of new low-temperature firing, low-dielectric

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APPENDIX E 263 TABLE E.2 Comparison of Glass Ceramics Characteristics Dielectric Thermal Relative Cost Constant Conductivity Material in 1984 (at 1 GHz) (W/cm-K) Silicon carbide 20 15 Beryllia 20 6.5 Aluminum nitride 15 Alumina ~ Glass ceramic 5 . . 9.0 9.5 5.0 270 240 60-140 17 10 SOURCES: Data from MCC. constant glass ceramic offers both Tower dielectric constants and the ability to use low-resistivity, thick-fiIm conductor systems, which wiD permit higher signal speeds. (According to several Japanese compa- nies using glass ceramics, lower resistivity materials permit the use of narrower conductors that in turn reduce capacitance.) The Japanese intend to use glass ceramics in high-performance systems. Table E.2 compares the costs, dielectric constants, and thermal conductivity as reported by the seven principal Japanese companies. Japanese success in investigating new substrate materials is im- pressive, particularly the ceramic and glass-ceramic materials with high-thermal conductivity and low-dielectric constants (SIC and AIN). MIT] has targeted ceramics as a core technology within the program to develop basic technologies for the next generation of Japanese industries. As of 1987, Japanese-produced {C substrates and packages had a 61 percent share of the world ceramics market (Ceramics Bulletin, Vol. 62, No. 5~. Table E.3 lists the Japanese companies actively investigating new ceramics. Hitachi is vertically integrated, including both a chemical and an electronics company, and has developed perhaps the most effi- cient interplay of these two strengths. One example is its devel- opment of beryBia-doped silicon carbide for high thermal conduc- tivity, heat-spreading substrates for multichip, high-power bipolar memory modules to permit air-cooling in high-performance com- puters. Other examples are Hitachi's high-purity encapsulants and high-quality-controlled polyimides. Toshiba has also been aggres- sive in developing high-thermal-conductivity ceramics. Toshiba has reported on high-thermal-conductivity aluminum nitride, and has

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264 APPENDIX E TABLE E.3 New Ceramics Research by Japanese Companies Other Glass Low-Temperature Company SiC A1N Ceramic Ceramics Hitachi x x NEC x x x NTT x Toshiba x x x Fujitsu x x Mitsubishi x Shinko x x SOURCE: D ata from MCC. TABLE E.4 Current and Projected Availability of Japanese Ceramics Material Status Alumina Aluminum nitride Glans ceramic Silicon carbide Beryllia In production Direct copper-bonded product went into production in late 1985, other products in 1987-1988 Developed; entering production Single layer available now; multilayer is in development In production SOURCE: Data from MCC. argued that economic considerations and the ease of fabricating flat materials make this a preferred choice. The current and projected availability of ceramics from Japanese vendors is described in Table E.4.