Noise Suppression Filter Guide

The secret story behind the birth of chip ferrite beads (part 2/2)

This article is a continuation of "The secret story behind the birth of chip ferrite beads (part 1/2)".


Discussions of "What should we name the product?" and "What should we call it in Japanese?" arose in parallel with product development. We investigated Murata Manufacturing's product naming system and came up with a number of proposals. It had already been decided to use BL (beads), but the third letter and the characteristics notation became subjects of discussion. BL+M (Multilayer) was selected from among the various product name proposals, and the product name was decided as BLM41A01. (A number of years later, as the number of product types increased, the name was revised to BLM41AG700.) 

On the other hand, there were few good proposals for the Japanese name. After a few days, our General Manager came to work one morning and said, "How about 'chip solid inductor' as the Japanese name?" And with that it was decided. Actually, the Japanese name was also changed a number of years later to the "chip bead inductor" currently used in Europe and America...

[BLM series shipment support]

After the product design examination was completed, our Manager took various materials introducing the new products and commenced PR activities to customers. Even though the products were introduced only via PR materials, about a week later we received a report that a certain customer wanted to use the products in its printers. Well, that's when things really started getting hectic.

The only equipment we had on hand were an old laminator and external electrode coater from the Yokaichi Plant that we had received from the multilayer multilayer capacitor (GR series) line. We had no characteristic selector, taping machine, or other equipment whatsoever. Well, what were we to do? We checked through the sales representative how many units per week the customer would use, and from when, and began arranging with the Yokaichi Plant to prepare for production. We brought measuring instruments, embossed tape, jigs and tools to a Group company and asked them to handle the measurement and taping by manual operations. I'm fairly ceratin  it was around 7,000 units per week, but that was a small enough quantity that we were somehow able to handle it.

However, at that point our General Manager gave the order to construct a system capable of producing three million units per month. This was a shocking number to me, and my only thoughts were "Can we really sell that fantastic number?" and "Is it okay to introduce mass-production facilities for that quantity?" We visited the Head Office Production Technology Division (Yasu) together with people from the Yokaichi Plant to discuss which characteristics should be measured and what measurement items were required. We also visited facility manufacturers after that, and then at long last the first BST (BLM measurement and taping machine) was introduced to the Yokaichi Plant.

[BLM complaint and change to external electrodes]

We received a complaint less than a month after the start of BLM delivery. Our Manager said that there had been a problem at the customer, and told me to go with him to visit the customer the following day. So my first business trip to visit a customer turned out to be a complaint visit.

We were ushered into a meeting room that appeared to be a corridor divided by partitions, and listened to the details of the complaint. The complaint was that the products had been mounted using flow soldering, which was new at the time, and that electrode leaching had occurred. This marked the start of a brief but decisive battle.

First, we gained approval for tentative countermeasures to double-coat (form a thick film) the Ag/Pd, and received a grace period of approximately one month. We knew that for the actual countermeasures we would have to change to plated specifications. We visited Group companies continuously for days to ask them to investigate plating. At the time it was said that plating caused the electrode strength to drop, and we were told that we would need to develop a thick-film electrode that could support plating. However, we were dealing with a complaint, so we did not have the time for that. Instead, we collected and evaluated all of the more than 10 different types of thick-film electrodes used within Murata Manufacturing at the time, determined the thick-film electrode with the highest strength, and ultimately used that electrode to deal with the customer's complaint.

As a result of this complaint, the external electrode specifications were changed to the current Ag thick film + Ni/Sn plating specifications just a few months after commercialization.

[Acknowledgements and thanks]

I feel that we were able to develop and support mass production of BLM series products in a short time thanks to the cooperation of persons in charge of the previously developed multilayer multilayer capacitors (GR series) and chip coils (LQH series), Group companies that helped with mounting evaluation and plating, and the Plant for mass production.

Even 27 years later, I am fortunate to have the opportunity to still work together with the people I met and struggled together with at that time. I am extremely grateful to have been able to participate in this enjoyable product development and for the extensive experience gained .

Since then, the chip ferrite beads series has been developed to include many different product types including array products (8, 6 and 4 elements) and products that support high-speed signal frequencies. But this growth into a major product line is a story for the next time... (Look forward to it!)


Written by: H.T., EMI Division, Murata Manufacturing Co., Ltd.

The information presented in this article was current as of the date of publication. Please note that it may differ from the latest information.

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