Space and Electronics

The Space Market

Space is booming. The business opportunities are vast. The space market is currently experiencing significant growth and evolution, driven by a variety of factors including advances in technology, new business models, and increased government and private investment. Some key trends and developments in the space market include:

• Increased Private Investment from companies like SpaceX and Blue Origin. Private investment has helped to spur innovation and competition in the space industry, leading to new technologies and lower costs.
• Growing Commercial Space Industry, with new players emerging in areas like satellite internet, space tourism, and asteroid mining.
• More Accessible Launch Services are making it easier and more affordable to get into space, with companies like SpaceX and Rocket Lab offering lower-cost launch services.
• Emerging Space Nations, with more countries investing in space programs and developing their own space capabilities.
• Increased Focus on Sustainability: As the space industry grows, there is also a greater focus on sustainability and responsible space practices. This includes efforts to reduce space debris, improve satellite design and manufacturing, and promote ethical behavior in space activities.

Many of the opportunities in space are requiring new and innovative electronics and communications capabilities.

Electronics in Space

Electronics face several challenges in space due to the harsh environment and unique conditions found beyond Earth's atmosphere. Some of these challenges include:

• Temperature: The temperature in space can range from extremely hot to extremely cold depending on whether an object is exposed to the sun or not. Electronics can overheat or freeze, leading to malfunctions or failure. Engineers must design electronic systems to operate in a wide range of temperatures. This article will focus on this challenge.
• Radiation: Space is filled with high-energy particles, such as cosmic rays and solar radiation, which can damage electronics and cause errors or failures in electronic systems.
• Vibration and Shock: Launching a spacecraft involves a lot of vibration and shock, which can damage electronics.
• Power Supply: Power is a crucial resource in space, and electronic systems need to be designed to operate efficiently on limited power.
• Communication: Communication with electronic systems in space can be challenging due to the large distances involved.

Engineers and system designers must take these challenges into account to ensure the success of space missions.

Temperature in Space: It’s Really Hot and Really Cold

Electronics used in space face a number of thermal issues that are not typically encountered in terrestrial applications. Some of the most common thermal issues in space electronics include:

• Temperature extremes: In space, electronics can be exposed to extreme temperature fluctuations, ranging from very cold (close to absolute zero) to very hot (over 100°C). This can cause stress and strain on the components, which can lead to failures and other issues.
• Thermal cycling: The temperature extremes in space can cause thermal cycling, which can cause materials to expand and contract, leading to stress and strain on the components. This can lead to failures over time, especially in materials with large coefficients of thermal expansion (CTE).
• Radiative heat transfer: In the vacuum of space, heat transfer occurs primarily through radiation, which can be a challenge to manage. Components that are exposed to direct sunlight can experience very high temperatures, while components in shadow can be very cold.
• Limited cooling options: In space, cooling options are limited due to the lack of an atmosphere and the absence of convective heat transfer. This means that electronics must rely on other cooling methods, such as thermal radiators or other passive cooling systems.
• Radiation effects: Electronics in space can also be exposed to high levels of radiation, which can cause material degradation, device failure, and other issues.

Overall, managing the thermal issues in space electronics requires careful attention to materials selection, thermal design, and testing. By designing electronics with thermal issues in mind, it is possible to create reliable and high-performing components that can withstand the harsh conditions of space.

Coefficient of Thermal Expansion (CTE)

The foundation for most smart electronics is the integrated circuit, which requires semiconductors. The coefficient of thermal expansion (CTE) refers to the rate at which the dimensions of a semiconductor material will change as a function of changes in temperature. More specifically, CTE is defined as the fractional change in length, area, or volume of a material per unit change in temperature.

Traditional semiconductor materials typically have a CTE that is lower than that of most other materials, which can lead to a number of challenges in semiconductor manufacturing and packaging. CTE mismatch can cause stresses and strains to develop in the device, which can lead to failure or reduced performance.

To minimize the effects of CTE mismatch in semiconductor devices, a number of techniques are used. For example, materials with similar CTE values may be used for the semiconductor and the package to reduce the mismatch. In addition, the use of specialized packaging techniques, such as flip-chip bonding or wire bonding, can help to reduce the stresses on the device and improve its overall reliability.

RF Filters and CTE

In the context of RF filters for space applications, low CTE materials are preferred because they can help to ensure that the filter maintains its performance and reliability over a wide range of operating temperatures.

In space applications, RF filters may be exposed to extreme temperature variations, as they are subject to the wide temperature swings that can occur in orbit. These temperature variations can cause materials to expand or contract, which can in turn affect the performance of the filter. For this reason, low CTE materials are often used to help ensure that the filter's performance remains consistent over a wide range of operating temperatures.

There are many different low CTE materials, including ceramics, composites, and various metal alloys. And fused silica, sometimes shortened as “glass.” These materials typically have a CTE that is significantly lower than that of conventional materials, like aluminum or copper. By using low CTE materials, it is possible to minimize the effects of temperature variations on the filter's performance, which can help to ensure that the filter meets the demanding requirements of space applications.

Comparing CTE of Fused Silica to Other Substrates

Fused silica is a type of glass that has a very low coefficient of thermal expansion (CTE) compared to many other substrate materials. In fact, fused silica has one of the lowest CTE values of any commonly used substrate material.

For comparison, here are some typical CTE values for various substrate materials:

1. Fused silica: 0.55 x 10^-6 /°C
2. Silicon: 2.6 x 10^-6 /°C
3. Alumina (ceramic): 8.2 x 10^-6 /°C
4. Aluminum nitride (ceramic): 4.5 x 10^-6 /°C
5. Copper tungsten (metal matrix composite): 6.5 x 10^-6 /°C

As you can see, fused silica has a much lower CTE than most other commonly used substrate materials, which can make it a good choice for applications where dimensional stability is important, such as in optics, MEMS devices, and other precision instruments. However, it is also more brittle than some other materials, which can make it more prone to cracking or breaking under stress.

Overall, the choice of substrate material depends on the specific requirements of the application, and a number of factors should be considered beyond just the CTE, such as the mechanical strength, thermal conductivity, and other properties of the material.

ED2 Corporation offers a number of RF passives produced in fused silica. Our Advanced Glass Packaging Technology (AGPT?) is a perfect choice for delivering high-performance, reliable, solutions for space.

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