（Left）
Takayuki Kubo
Sales Div. Group
Joined Shindengen in 1995.Mr. Kubo is responsible for customers in a variety of industries, with a focus on the home electronics and automotive markets.

(Right)
Toshikazu Arai
Electronic Device  Div. Group　Assistant Specialist
Joined Shindengen in 1997. Mr. Arai works on development of discrete semiconductors with a focus on diodes and thyristors.

Kubo：
A customer who I worked with at the time was using bridge diodes from another manufacturer, but the customer struggled with the very poor heat dissipation of those products.

The bridge diodes the customer was using at the time were a large current type with an output current of 25A or higher in a 5S package. There was very little selection of products capable of output of large current at that time, so the customer had little choice but to use those products...

It was under these circumstances that the customer made a request, "Bridge diodes which could output 25A or higher while maintaining the same 5S package external dimensions but with lower heat generation. Since Shindengen is specialized in the manufacture of diodes, would it be possible to make such a product?". I was very happy when they made the request. I felt that they made the request because they had such faith in our company and I wanted to help them solve their issue.

However, in order to develop larger current products which could support 25A or higher, it was necessary to completely revise the internal structure of the 5S package. The 5S package had a long history of use, and making changes to something that had remained unchanged for so long requires a great deal of energy and effort to overcome that inertia. So, gathering the "courage to change", we held talks internally multiple times, slowly gaining understanding and cooperation, until the development of the new "5S GEN2" internal structure was decided upon. It was also decided to commercially develop the new D35XB80 product which would allow for output of 35A, exceeding the previous threshold of 25A output.

Arai：
If we were to just install a larger chip in the same package, we would be able to achieve larger current capacity. However, if we did that, when that larger current flowed, it would make it easier for the overall package temperature to also increase, causing heat generation issues. The product from a different manufacturer which the customer had been using also had an issue where the temperature of the terminals would rise during operation, causing temperature increases to occur on specific terminals leading to an imbalance in temperature distribution. As a result the overall package temperature would increase and result in extreme temperature imbalances.

In order to increase the heat dissipation of the 5S package and overcome these issues we carried out repeated testing through simulation of over 30 different internal structure patterns. We searched for the most optimal combinations by changing various conditions, such as the lead frame width, the chip layout positions, mold resin thickness, etc., and testing combinations of these changes.

The 5S GEN2 came about as the result of these attempts. This new package type maintains the same 5S external dimensions, while improving heat dissipation to allow for mounting of larger current chips, and greatly increasing the maximum current capacity from the previous 25A to 35A.

If we were able to change the external dimensions, it would not be so difficult to achieve higher current capacities; however this development was based on a request from a customer to achieve this while maintaining the same 5S package external dimensions. There were a lot of limitations to overcome and we had quite a difficult time finally arriving at the optimal internal structure.

Arai：
We finally had a sample ready and when we asked the customer to assess it, they immediately carried out assessment for us. The customer happily reported that, "we had solved the heat generation problem the customer had struggled with when using the other company's products!", which was extremely gratifying.

We also received praise from superiors that we had succeeded in changing something that had remained unchanged for so long, and completed a development which would be sure to become a part of company history, which made the entire experience very memorable. We also received a company award for outstanding technological development. I am very proud that something I designed was able to be incorporated as a variation for packages which have been sold for so long.

Kubo：
Coordinating the customer's mass production schedule and our internal development schedule was very difficult. At first, development was not able to keep up with the schedule which the customer expected. However, we kept repeatedly telling the involved personnel that the customer was placing a lot of faith in and had great expectations of our company, which slowly changed the atmosphere inside the company and helped to generate a sense of togetherness. We were able to respond to each customer inquiry quickly and accurately because of our strong internal cooperation.

Going forward, as a salesperson I would like to continue to dedicate myself to being able to propose better products by being attentive to customer needs and being willing to cooperate. I want to all of Shindengen to work in unison to meet customer expectations!

Mr. Arai and Mr. Kubo talk about the amazing facets of the D35XB80!

POINT 1: Maintaining the industry standard 5S package
Because the external dimensions of the widely adopted and relied upon 5S package remain the same, there is no need to change boards or mounting processes when switching from previous products.

POINT 2: Lead temperatures of 100℃ and lower
(with 25℃ water cooled heat dissipation fins attached at 35A output)
POINT 3: Extremely low temperature variation among terminals
For the 5S GEN2, we achieved for the most optimal combinations by changing various conditions, such as the lead frame width, the chip layout positions, mold resin thickness, etc., and testing combinations of these changes. This allowed us to successfully decrease and equalize terminal temperatures. This will greatly contribute to board mounting reliability for customers.