Proven technology allows resistors and sensors to be printed directly on the board.
Today’s electronics are characterized by two conflicting demands: more power and less space. As users come to expect more capabilities from ever smaller electronics, electrical engineers are in need of innovative and efficient new solutions for packing more components into shrinking board space. However, this pressure isn’t limited to iPhones, tablets, and other handheld devices. It’s also being levied on power applications, industrial applications, harsh environment applications, and extreme heat applications.
While there is a push to miniaturize all possible aspects of circuitry, passive components such as resistors and capacitors still consume a majority of board space in most electronic devices. This means that they can quickly become a problem for products that require a large number of resistors, particularly physically larger power resistors.
For applications such as these, alumina substrate technology can offer a useful solution. Although the technology has been around for decades, it has enjoyed a renewed popularity in recent years as the use of microcircuits and hybrid microcircuits has increased. Alumina substrate offers two particular advantages to engineers constructing circuitry for power applications: (1) as a ceramic, alumina offers excellent heat dissipation (2) resistors can be printed directly onto the board, saving crucial space.
Efficient heat dissipation is crucial for reliable and long-lasting performance in high-power applications, and alumina’s high thermal conductivity is ideal for handling power and heat. Competing, less expensive technologies such as PCBs do not dissipate heat, meaning that more resistors, heat sinks, and other space-consuming components are required to do the work of thermal management.
With printed circuit boards, chip resistors must also be placed on top on the board, and other components cannot be placed on top of them. They therefore take up significant space. With alumina substrate, on the other hand, manufacturers can print resistors directly onto the surface of the board. These resistors are very thin, approximately the same height as the copper conductive traces on a PCB, permitting efficient use of board space. Manufacturers can also place components directly on top of these resistors while still making conductor traces between them, doubling the utilization of space. While components such as transistors and diodes must still be surface mounted on alumina substrate, the space saved on resistors adds up to big benefits for power applications.
Since alumina substrate permit both effective heat dissipation and direct printing of resistors onto the board, it is particularly suitable for temperature regulation in products like irons, coffee cup warmers, hair straighteners, and other heat-intensive items. Temperature sensors can actually be printed directly onto the board, just like the resistors mentioned above, and this significantly reduces space consumption while also ensuring that the sensor can be mounted closer to a heat source for quicker response time. As a result of alumina’s heat dissipation characteristics, the sensor is exposed to a precise, even temperature, and users do not have to worry about error due to hot-spotting or other irregularities.
In sum, alumina substrate offers significant advantages for high-power and high-heat applications in industry, harsh environments, or consumer products. Since components such as resistors can be printed directly on the board, with other components mounted on top of them, it offers design flexibility that makes it easier to meet the requirements of increasingly complex and compact applications. Alumina substrate technology can be found in cars, tractors, personal water craft, elevators, heaters, and even some of the items in space.
MIKE WEST is director of engineering at Ohmite Manufacturing;
