Site: Fujitsu (Yamagata Plant)
1-6-1 Marunouchi, Chiyoda-Ku,
Tokyo 100, Japan
Date Visited: October 6, 1993
Report Author: M. Pecht
Fujitsu manufactures and automates to the level needed to reduce costs and improve quality incrementally; nothing more, nothing less.
Our JTEC group spent a half day at Yamagata Fujitsu (Fujitsu's Yamagata plant). The main technology that we came to see was Fujitsu's high-volume surface mount operations that are part of its manufacturing process for hard disk drives used in PCs and workstations. We were greeted by Chiaki Handa, President of the Yamagata plant, and by T. Tsuchimoto, Board Director and General Manager of the Technology Group at the Kawasaki Facility, who gave a general overview of the operations of Fujitsu. Then M. Nakazono, Director and General Manager of the Yamagata plant, gave the Yamagata plant overview. Altogether there were 12 managers from three different Fujitsu facilities (Yamagata, Kawasaki, and Atsugi).
Fujitsu has some 71 overseas manufacturing and assembly-and-repair subsidiaries, in addition to numerous sales and other offices. It currently lists 161,974 employees worldwide. (This number does not include employees from Amdahl and other similar affiliates in Europe.) In addition to manufacturing computers, Fujitsu has entered the multimedia market and has been chosen by U.S. common carriers for broadband ISDN equipment, switching systems, optical transmission systems, and cellular mobile phones; it is offering similar equipment in parts of Asia, Australia, and Europe. It is also moving into software and other computer services around the world.
Yamagata Fujitsu is located in Japan's industrial district. Established in 1983, it had 100% investment by Fujitsu; 70% of sales go overseas. As of the JTEC visit, approximately 300 of 1,000 employees were staff, approximately 700 were operators; about 60% were male and 40% female; their average age was 24. The plant developed, produced, and managed sales of disk drives. The JTEC group The JTEC group toured the printed circuit board (PCB) assembly line (PCA) for 3-1/2 inch disk drives and the 2-1/2 inch hard disk drive assembly line (HDA).
Printed Circuit Assembly Line for 3-1/2 Inch Disk Drives
Yamagata Fujitsu's PCA line incorporates traditional semiautomatic component placement, soldering, and cleaning equipment with manual part and assembly feeding of machines. There was some manual part soldering and a lot of manual inspection, testing, and repair. The reasons given for all the manual work were (1) it was the most cost-effective considering the mix of PCA technologies they needed to handle, (2) there were many odd parts, such as special connectors and heat sinks that didn't easily lend themselves to automation, and (3) product demand was low, so that only two shifts were needed and further automation would not pay off. Over 600 pieces per minute could be manufactured. The components were predominantly plastic. Generally 60% of the boards were composed of SMT; 20% of these were single-sided and double-sided boards, 45% were four-layer, 30% were six-layer, and 5% were eight layers and up. In general the PCA process line was not by any means state-of-the-art and may not even be highly profitable. It was stated that the demand for these products was down.
The 3-1/2 inch drive had a lot of manual handling: for insertion of some components, for rework, and for inspection. Burn-in equipment at the plant operates under the following conditions:
The cleaning operation was OK, but there was so much handling after the cleaning with bare hands that it seemed as if the cleaning was somewhat superfluous. Of some special interest in the PCA manufacturing line was the removal of CFCs in October 1993 and the subsequent use of non-CFCs, replaced by a deionized water cleaning process. While there was no research being conducted in leadless solder, management was aware of efforts in Germany and did look at InSn, but considered it too expensive.
The small FR-4 boards (to be mounted in hard drives) were demarked and partially cut out but remained in the larger mother boards for handling. Each mother board contained four or six smaller active boards. They were loaded with pick-and-place machines (said to have a placement accuracy of 50 microns - at other sites we saw machines that were more accurate, but 50 microns was apparently adequate for the purpose). The boards were reflow soldered.
In summary, the printed circuit line for 3-1/2 inch discs was "low tech": the machinery was old; the process was a combination of automated and manual assembly; there was lots of inspection; cleanliness was minimal; the burn-in was primitive. It was clear, however, that the important processes were well developed, and all the things we saw that seemed "low-tech" were indeed relatively unimportant (e.g., the burn-in caught what it needed to catch, and having a more sophisticated burn-in system was unnecessary, and hence no attention was paid to it). Thus, the operation appeared efficient for what it was doing, even though it was not elegant. It was obvious that Fujitsu has no intention of significantly improving this line. It was also obvious that Fujitsu was going to use what it learned on this line to make a step-wise improvement on its 2-1/2 inch drive assembly.
It should be noted that the Yamagata plant is dedicated to manufacturing products for personal use, different from any other Fujitsu plant, such as its Numazu plant, which manufactures high-technology products. The main focus of the Yamagata plant is to utilize the existing equipment to a maximum extent to promptly manufacture high-quality products and at the same time to seek better production efficiency at a lower cost.
As pointed out to the JTEC team, the Yamagata plant uses traditional manufacturing methods through semiautomated equipment and manual work on its printed circuit board assembly lines. While installed machines at the Yamagata plant such as screen-printer, parts-mounter, and air-reflow oven may be obsolete from the technical point of view and give the impression that the Yamagata plant continues to use old equipment, our hosts noted that the use of this equipment is optimal from the point of view of efficient investment.
The plant does utilize an automatic appearance inspection tester for any minimum-size parts such as QFP (quad flat package) with 0.5 lead-pitch and 1005 chips, which are almost impossible to inspect manually. On the other hand, inspection and repair of any parts other than those minimum-size ones are carried out by manual tasks to maintain efficiency in capital investment.
Hard Disk Assembly Line
The hard disk drive assembly (HDA) line was highly automated and the equipment was modern and sophisticated. The environment was a 100-class clean room (not great by semiconductor standards, but certainly sufficient for the operation, especially since extra precautions were taken on the equipment where the magnetic heads were physically present), with automated testing of over 100 drives simultaneously. There was complete robotic handling of parts. The operators all wore appropriate clean-room clothing. This line was being prepared for high-volume production. The hard disk assembly operation was a model of efficiency. The entire operation was automated using Fujitsu-built robots and required attention to technology and detail. The striking difference between the PC board assembly area and the hard disk area was attributed (by us) to the fact that the disk was the guts, the family jewels, of the Fujitsu system; hence, no expense was spared to make this as efficient and low-cost as possible.
We saw very little in terms of new technologies, but our hosts did mention various technical activities in other parts of Fujitsu, including 16-to-42-layer PC boards, 60-layer ceramic laminates used in its supercomputers, and the newest parallel supercomputer using GaAs chips. (These are mounted in single-chip packages that are then mounted on ceramic boards in order to get around the known-good-die problem.) Fujitsu was using opto-connections for external connections but using electrical connections inside. It developed its own router for these boards.
Our hosts also mentioned a new (but published in MRS in 1992) photosensitive dielectric film using a blend of polymers that can be used for cheap MCM-D circuit boards. Line widths were 30 microns, and vias were claimed to be about 20 microns in diameter. They used Al metal lines and made up to four metal and four dielectric layers. They said this might be in production within two to three years.
Our hosts said they were following the work in BGAs including the OMPAC by Motorola and some products by AMD. They were conducting some work in flexible PCB manufacturing and assembly, flip chip mounting and TAB mounting, with plans for bare chip assembly on a computer product (server) in 1994.
Quality and Reliability
Quality and reliability were assumed, but never initiated as a topic of discussion by our hosts. Their policy is summed up as "quality built-in," with cost and performance as prime considerations. Our hosts noted that today's components do not require burn-in, although at the board level there was some concern for solder bridges.
In February 1993 Yamagata Fujitsu became ISO 9002-certified and at the time of our visit was expecting to be 9001-certified later in 1993 - the purpose is to be able to sell products in Europe.
As in other Japanese factories the Yamagata plant management paid attention to running equipment well, to continuous improvement, to cost reduction, and to size reduction. No magic technology was employed; just fruits of a detailed study and execution of automated processing and smooth-running, efficient operations.
Fujitsu is motivated to improve circuit board density and reduce cost. The improvement in density had several implications; for example, to reduce package thickness, to improve mounting location, and to reduce weight. Reducing cost was the prime driver after functionality and customer needs were accounted for.
To meet the objectives, Fujitsu was going to use flexible printed circuits, improved soldering technology, design of thinner packages, and specially plated through-holes. None of the technologies are revolutionary; rather, they are the straightforward application of continuous improvement to Fujitsu product lines.
A Fujitsu representative aptly stated, "Indeed, we are still using an old-type equipment for the printed circuit board assembly line for 3.5 inch disk drives. We would like to stress, however, that the use of the fully automated equipment does not always represent 'high technology.' Through our experience over years, we have come to the conclusion that in certain cases manual work is sometimes more efficient rather than automated machines, as other vendors do in some cases."