A Mutual Understanding of Thermal Design

In the previous article, the need for thermal design that follows changing design trends was explained. This article explains how the thermal design of recent years will not take effect if it is not based on mutual understanding among all the engineering divisions involved in equipment design. If this prologue that precedes a detailed explanation of thermal design has been somewhat long, it is because of the need to understand not only the engineering aspects of thermal design issues in recent years, but also the closely related environment and system aspects surrounding thermal design.

A Mutual Understanding of Thermal Design

Product design involves, broadly, electronic circuit design, mounting board (PCB) design, mechanical design, and software design. Conventionally, these are each performed by specialized design engineers and sections in charge, allocating tasks appropriately; for example, an electronic circuit design engineer selects components that satisfy product specs and designs the circuit, whereas a software designer develops software to run on the hardware, a PCB design engineer designs the PCB taking into account appropriate component positioning and layout, the PCB size, and so on. And, a mechanical design engineer designs housings, structures and the like.

When considering the thermal design that is being sought in such a situation, if each design engineer does not incorporate thermal design into his own design area and share this with other designers to achieve a unified product design, it can be said that arriving at a product with an optimized thermal design will be difficult.

For example, fanless specs are studied as a way to cope with the equipment trends of miniaturization, quieter operation, and reduced costs. Where fans are present, they will probably be the responsibility of the mechanical design engineer, who normally handles matters relating to cooling in a housing; but when fans are eliminated, which design engineer will be dealing with cooling? This diagram cites examples of how different design engineers could handle thermal design.

As the reader has probably noticed on seeing the above diagram, each of the design engineers reduces heat generation within his own scope or category, or uses measures to increase heat dissipation, and these various measures are interrelated to achieve a fanless design. Often this requires communication between engineers, and without mutual understanding, the intentions of the individual engineers cannot be expected to bear fruit. Moreover, there is increased possibility that an engineer may be alerted to something he would not have been aware of working in his own area, and consequently may hit upon a more effective solution.

What Becomes Possible through Optimization of Thermal Design Based on Mutual Understanding

There is the term “design quality.” Put simply, when prototypes are fabricated according to a design and no problems arise, so that mass production begins in a short period, and no problems arise in the marketplace as well, the design is said to be a high-quality design. While not limited to thermal design, design of high quality is universally desired. Hence improvement of design quality is important, and in addition to the thermal design satisfying current requests, the establishment of evaluation criteria, and the mutual understanding with respect to thermal design that have been described up till now, it is essential that engineers “come to grips with” thermal design.

As a practical matter, shortages of manpower and cost prioritization are real problems; but enhancing design quality ultimately leads to resolution of these problems as well. Improvement of design quality can reduce the number of prototype cycles, as indicated in the diagram below. This results in significant cost reduction, and by reducing the repetition of tasks, manpower use as well as costs can be decreased.

From the next article, we will explain the fundamentals of thermal design and heat dissipation.