Manufacturing that Challenges Industry Norms: Semiconductor Supplier ROHM Develops a New ‘Flexible’ Production Line

September 18th, 2024

ROHM wurde 1954 in Kyoto gegründet und ist ein Halbleiterhersteller. Zunächst bot das Unternehmen Widerstände an, entwickelte dann aber auch Transistoren, Dioden und ICs, wobei der Schwerpunkt in jüngster Zeit auf SiC-Halbleitern lag, die die Dekarbonisierung beschleunigen dürften. 1971 gründete ROHM als erstes japanisches Unternehmen eine Präsenz im Silicon Valley. Jetzt, mit einem weltweiten Netzwerk von Vertriebs-, Entwicklungs- und Produktionsstandorten, entwickeln wir uns weiterhin zu einem globalen Unternehmen mit Sitz in Japan.
ROHM believes that the most important way to become a company that is chosen by customers and other stakeholders around the world is through manufacturing that values the idea of quality first. This time, we will introduce ROHM’s next-generation ‘Flexible Lines,’ the first in the industry to achieve high-mix, low volume production based on thorough quality design.

Flexible Lines

In-House Production Systems Ensure a Stable Supply of High-Quality Products

In line with a corporate objective of ‘Quality First,’ ROHM has developed its own production systems to ensure a stable supply of high-quality products since the company was established in 1954. These production systems are constantly evolving in tandem with the evolution of the electronics industry.
For example, in back-end production, where semiconductor chips are diced and sealed in packages, we developed the original first-generation line in the 1980s. In the 1990s, we created an integrated production hoop line, and in the 2000s when the market expanded globally we established a wide line to achieve mass production, improve quality, and lower costs.
In addition to mass production, recently there has been an increasing number of requests for small-lot production in the automotive and industrial equipment markets, as well as from customers developing new products. So in 2021, ROHM deployed a ‘flexible line’ that achieves high quality design ideal for high-mix, low-volume production by reducing quality variations and minimizing human intervention as much as possible.

Production Systems

A New ‘Flexible’ Production Line that Overturns the Industry’s Conventional Wisdom

ROHM’s flexible line is a next-generation production line developed by combining the concepts of high-mix low-volume production with thorough high-quality design.
At ROHM Apollo's Hirokawa plant in Fukuoka (Japan) prefecture currently in operation, three sets of equipment are lined up in a U shape, with AGVs (Automated Guided Vehicles) running between them. Engineers monitor the status of all lines via monitors in an adjacent control room.

Flexible Lines

High-mix low-volume production
Why select the concept of high-mix, low-volume production? Mr. Miwa, head of the Manufacturing Innovation Division who has been involved in the construction of production systems for many years, explains the reasons as follows.
'There are a number of customers in the automotive and industrial equipment fields that demand a consistent supply of components in small quantities for a long period of time. In response, we believed we can provide a stable supply by establishing a system not centered on mass production that uses wide lines for large orders and flexible lines for smaller quantities.
However, in the semiconductor industry where mass production and inventory design are the norm, we are tackling high-mix/low volume production for the first time. This in itself was a challenge!'

Tadatoshi Miwa, General Manager
<Tadatoshi Miwa, General Manager, Manufacturing Innovation Division, ROHM Co., Ltd.>

Generally, mass production lines require manual replacement of jigs and tools such as molds at each process when producing different products, along with fine-tuning and optimizing equipment. As such, these lines are subject to frequent changeovers during high-mix-low-volume production that can affect line utilization rates and product quality. ROHM’s new flexible line automates the switching process that was previously performed manually. Now we can produce multiple products on a single line while ensuring quality even with small-lot production.

Thorough High-Quality Design
The underlying concept of thorough quality design was born from our pursuit to develop a zero-defect manufacturing system that does not produce defective products to meet the increasingly stringent quality requirements in the automotive field.
In wide line mass production, quality is enhanced by introducing inspection at each step of the process in addition to product sorting at the end of the process. In contrast, our flexible line has adopted a bold policy of high-quality design, says Mr. Ariga, Division Manager of ROHM’s Manufacturing Innovation Division.
‘Our policy is to improve quality at each step of the process.
The key is to minimize variations in 5M1E (Man, Method, Measurement, Material, Machine, and the Environment).’

Kenji Ariga, Division Manager
<Kenji Ariga, Division Manager, Development Segment, Manufacturing Innovation Division, ROHM Co., Ltd.>

Take machine variation as an example. In the past, multiple jigs and tools were used for a single process, invariably resulting in minute variations in quality. Our flexible line uses a simple system of one jig, one tool, and one process to reduce machine-related variations.
We also consider people to be one of the factors that contribute to variation, and have automated all line switching, inspection, supply, and other tasks that were previously performed by hand. We are working to stabilize quality by reducing human intervention as much as possible.
Furthermore, instead of relying on the experiences and intuition of skilled workers, we visualize machines, materials, and processing conditions to prevent problems caused by variations. In the unlikely event of a problem, thorough traceability allows us to identify the root cause in real time, down to the individual product itself.
Our flexible line minimizes these variations to achieve a defect rate of 1 out of 500 million pieces (process capability index CPK=2.0 or higher), compared to a typical production line with a ratio of approx. 30,000 out of 500 million pcs (CPK=1.33). This tells us that our goal of high-quality design has been achieved.

Production Lines Effective for BCP and Environmental Measures

As flexible lines have a very high rate of automation, installing the exact same equipment at multiple locations will make it possible to manufacture products with the same quality anytime, anywhere. In this era of global uncertainty, we can become a trusted presence capable of providing a consistent supply of products to customers worldwide.
We can also use the data collected to further visualize and keep track of energy usage at all times. As global environmental conservation becomes a major issue, we believe in contributing to manufacturing that improves energy savings while reducing CO2 emissions from electricity.

BCP: Business Continuity Plan

The Keys to Development: A Vertically Integrated Production System and Technology Inheritance

Since the project was launched in 2018 it took about a year and a half to reach the mass production verification stage. There are two major reasons we were able to overcome various difficulties and develop a flexible line.

The first is inheriting production technology accumulated for over 60 years. At ROHM's Development Center HQ, design, prototype evaluation, and mass production evaluation of various manufacturing equipment used in Japan and overseas are conducted on a daily basis. It is also a place for young engineers to learn about manufacturing, with knowledge and expertise passed down from one generation to the next utilized in the development of new production lines.

Flexible Lines

The second is an environment that allows for close coordination and exchange of opinions across departments. This is created through ROHM’s ‘Vertically Integrated Production System,’ in which development, design, production (including wafer manufacturing), together with sales and services are carried out within the group.
Continuously brushing up from a variety of perspectives, including technological development, production/manufacturing technologies, and establishing a long-term collaborative system within the company, led to the development of a groundbreaking new line that challenges conventional norms in the semiconductor industry.

ONE ROHM

Towards a New Manufacturing Platform Trusted by Customers

The flexible lines currently in operation at ROHM Apollo's Hirokawa plant began producing samples for sales promotion in April 2021, followed by the commercial mass production of two types of discrete products the following year, in 2022. In the near future, we plan on expanding production to around 10 models, fully realizing our potential to produce 4.5 million pieces per month. We are also considering expanding the technology of flexible lines to domestic factories while expanding the number of compatible models.
At the same time, we are accumulating various technological verifications while carrying out mass production, with the goal of utilizing element technologies obtained in this process for future developments, such as unmanned wide lines for mass production and other next-generation lines.
The development and evolution of a new manufacturing platform trusted by customers around the world continues.

A video on ROHM’s website tells the story of ROHM’s manufacturing along with the individuals who are passionate about providing customers with consistently high-quality.

Stories of Manufacturing

A challenge in itself: Developing the industry's first flexible line.
https://www.rohm.com/company/about/stories-of-manufacturing/flexible-lines

Click here for the video.