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Basic information


updated on March 24, 2017

Development of the millimeter-wave LTCC substrate that achieved the lowest loss in the world

Hirai Seimitsu Kogyo Corporation

Project name Development of LTCC substrate with high-Q, low-permittivity and the capability of high-density assembly
Target downstream fields Automobile、Aircraft、Industrial equipment
Response to the needs of downstream companies High function (improved precision / performance)
High durability (improved heat resistance / corrosion resistance / abrasion resistance)
Mass reduction (size / weight reduction)
Optimization (improved productivity / work efficiency)
Reliability / safety (realization of highly reliable inspection technologies etc.)
Cost reduction (running cost reduction / loss elimination / labor saving)
Specific numerical values relating to the above needs ・Transmission line (MSL) loss is below 0.5 dB/cm
・LTCC is a proven technology in the automotive applications, such as ECU."
・Multi-layered LTCC enables the miniaturization of size and weight.
・Co-fired LTCC substrate requires just simple processs compared to complicated others.
・The LTCC substrates are stable, reliable and safe due to the firing.
・The miniaturized multi-layer LTCC substrate contributes to the low-loss and low-cost as well.
Project implementation period 2011~2013
Commercialization status Undergoing supplementary research (Project undergoing research toward completion)
Target materials LTCCs for substrates, dielectric ceramic materials

Project details

Project background
Although milli-meter wave technology was just to emergy next to microwave, it was not for long 40 years due to the device costs compared to the optical fibers, etc.. However, recently, advanced semiconductor device, C-MOS, extended its capability to mm-meter waves, and the C-MOS or SiGe devices are ready to be used in automotive collision avoidance radar, mm-meter WLAN (WiGig), etc. On the other hand, unfortunately the development of the substrates to put on or assemble the devices and components are on the way behind. The ancient waveguide and alumina substrates are too expensive and, hence, the mm-meter wave LTCC substrates which allow the compact integration of the antenna and modules are eagerly awaited for.
Points of R&D
The current dielectric material for multi-layer LTCC substrate, which is very useful for mobile phones, consists of a mixture of alumina particles and glass and allows low-temperature co-firing with silver paste. If this conventional LTCC substrate is used in the mm-meter wave band, the glass deteriorates the Q value inversely proportional to the frequency, resulting in too big loss. Therefore, in order to achieve the low loss at millimeter waves, high-Q materials should be developed which do not use glass. Willemite has a high Q value though the firing temperature is high, at about 1,400 degrees Celsius. We tried to lower the firing temperature by adding some additives and by adopting new firing concept, "adhesive sintering".
Specific R&D results
Slurry of the mixed powder of high Q material and some additives are made, casted to the green tape with the Doctor Blade and fired. The fired test substrate exhibited a transmission line (microstrip line, MSL) loss of 0.45 dB / cm @ 67 GHz, the lowest loss in the world. Furthermore, the relative permittivity was low enough, 6.1, and the minimum line and space was almost 60 / 60 um.

Anticipated fields / products etc. to which this technology may be applied in the future
It may be used for the integration of antennae, modules, components, devices, etc. in the mm-meter waveband. Particularly with battery-powered mobile and portable devices that require low loss, low power and low consumption of energy, the most preferable solution may be to integrate antennae and modules on a single substrate because the connection loss between the antennae and modules should be minimized. The LTCC substrate easily provides it. The developed mm-wave LTCC is expected to vitalize the industry by the creation of a new market.

Work toward commercialization

Activities related to intellectual property and publicity - Press release: Kagaku Sangyo Shimbun 2012 (JFCC), The Denpa Times 2013 (Hirai Seimitsu Kogyo)
- Exhibition: Nissan exhibition sponsored by Gifu, Aichi and Mie prefectures, Mazda exhibition, special exhibition at the Global Symposium on Milli-meter Wave 2013 and MWE2013 (all in 2013, Hirai Seimitsu Kogyo)
- Academic conference presentations: MMA2014, Idaho, USA in June 2014 and one more conference (all by Mr. Osato)
- Patent and utility models: No applications or corresponding matters. May be applied for in the future, particularly in relation to Ag diffusion measures and improvements in material quality.
Future outlook Offer of sample substrates for users' evaluation has started last July already. The conductor paste is either gold or silver and thin gold flash plating onto the silver pattern is available already. However, the thick gold plating for wire bonding is yet under development and will be coming soon.
Level of achievement based on the original goal, and new challenges The project targets three, high Q value, low permittivity and high-density assembly, the former two have already been achieved. The development of thick gold plating onto the Ag paste is continuing.
Inquiries from downstream industries Already approached several companies, including manufacturers of automobile radar and mm-meter wave WLAN.

System of R&D

Organization managing the project Japan Fine Ceramics Center
Certified business operators Hirai Seimitsu Kogyo Corporation, Yasufuku Ceramics Co., Ltd., Marusu Co., Ltd.
Institutions conducting the research Nagoya Institute of Technology, Meijo University, Tokyo Institute of Technology, Japan Fine Ceramics Center, National Institute of Advanced Industrial Science and Technology
Advisers Noboru Ichinose, professor emeritus at Waseda University, Yoshio Kobayashi, professor emeritus at Saitama University (the current president of Sumtec, Inc.), Kazushige Obayashi (R&D Center, NGK Spark Plug Co., Ltd.), Yasuo Omori (DH Material Inc.), Yukihiro Shimakata (R&D Center, Taiyo Yuden Co., Ltd.)

Promotion comments

The new mm-wave LTCC substrate enables to integrate antennae, transceiver RF circuits, base-bands, logic units and even microcomputers. It brings paramount benefits of miniaturization, low loss and low power consumption, and price competitiveness. For trial production or evaluation, support with mm-meter wave measurement (S- parameters, etc.), circuit design by using ADS, HFSS, etc. is provided as options.

Corporate information

Company name Hirai Seimitsu Kogyo Corporation
(Corporate Number:3120001069573)
Address 2-10-17 Doshin, Kita-ku, Osaka -shi, 530-0035, JAPAN
Phone number 81.584892394
Number of employees 400
Capital 101,996,000 yen
Business category Electric machinery and appliances manufacturing industry
Business content Manufacturer handling metal processing and ceramic (LTCC) processing, focusing on etching processing
URL http://www.hirai.co.jp
Production facilities owned and specifications Etching machines, laser processors, wire-cutting machines, firing furnaces, screen printers, warm isostatic press-laminaters, mm-wave network analyzer, probe station, 3D laser microscope
Production base area Domestic location:5-145 Yokozone, Ogaki-shi, Gifu-ken
Main clients Kyocera Corporation, Canon Inc., Sharp Corporation, Sony Corporation, Toyota Motor Corporation, Fujitsu Limited
Department handling inquiries for this project LTCC Technology Office ( fujimoto@hirai.co.jp )

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