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A New Era in Space Products - Radiation Tolerant

T.J. Fure - Product Marketing Manager
Gabino Alonso - Strategic Marketing Engineer
Mar 23rd 2016

Radiation Tolerant

Recent developments have made doing business in space ever more achievable to a broadening base of companies. A market previously consisting solely of major defense contractors and national governments has been disrupted by a growing list of commercial companies determined to deploy an enterprise beyond the confines of our terrestrial home. This paradigm shift is also driving new developments in space products that will have a dramatic and exciting effect on spacecraft size and performance in the future for all customers.

Promising commercial companies fill the news with reports of huge investments in space technology.  The cost of launch has dropped to the lowest level in history as companies develop new approaches to launch vehicles. Investments of up to $1B are going towards deploying constellations of low Earth orbit (LEO) satellites to connect people in remote corners of the globe. Other approaches to increasing internet connectivity include high altitude unmanned aerial vehicles (UAVs). These approaches require more integrated parts to build smaller, lighter platforms to achieve their goals.

Clearly the demand for innovation in space products has never been higher. Linear Technology has a long history in the space business of delivering the highest quality, reliability and resilience to the damaging effects of radiation in space. Our heritage line of Radiation Hardened (RH) products is well known in the industry to be hardened to over 200 krad, making these products suitable for the harshest orbits. In order to drive new product development at a faster pace, we have partnered with two premier hermetic packaging companies. These partners have helped us to focus on IC development while they provide their core competency of hermetic packaging and delivering products that are both technologically advanced and in smaller, more thermally efficient packages.

Linear Technology is well known for developing new IC’s for the commercial market that enable our customers to design smaller and more efficient products, however transitioning these to space qualified RH products is complex and time-consuming. The vast majority of new IC’s are built on BiCMOS processes which give us the capability to combine the best of bipolar and CMOS process technology. From a radiation tolerance perspective though, these BiCMOS devices require us to characterize and mitigate for the effects of both total ionizing dose (TID) as well as single event effects (SEE). This extends the development time for new products at a time when we need to release new products more rapidly.

Another factor driving new product development is packaging since many new products are being designed with unique packaging that enhances the performance of the commercial IC. In some cases transitioning a commercial product to space becomes impractical when its performance is tied directly to the existing non-hermetic package. This might include issues related to additional parasitic effects that require complete new hermetic package development, costly redevelopment of post package trim, or procurement of new highly complex test systems and handlers. Whatever the issue, we offer existing commercial products that previously had no chance to transition to space products because the investment was too great to justify.

Luckily, there are other forces at work that will allow us to develop more advanced products more rapidly. The first is that the total dose radiation requirements of LEO are lower than traditional orbits, so a product that can meet 30 – 50 krad tolerance is acceptable. The second is a ground swell of support to the idea of flying plastic encapsulated modules (PEMs) in space, an idea which until recently has been met with outright disdain from EEE parts managers and engineers. It will not be easy, but if done properly and accepted by the space community, will open the door to dramatic improvements in performance as well as reductions in size, weight, and power (SWAP) for the spacecraft.

Producing space qualified PEMS with the highest quality and reliability is crucial to our combined success. The major space agencies around the world have long had specifications for the post processing of PEMs to qualify them for space use. The space community has long resisted the use of PEMs due to inherent risks and uncertainties in the process, including lot traceability, validity of radiation test results, test program correlation, and lack of manufacturer warranty and support. It is costly and time consuming to do the testing and carries the risk of a lot failure leaving the designer to start the process over with a different part, add shielding, or include other mitigation techniques which add cost and weight. If we as the manufacturer offer a space qualified PEMs product, those risks are greatly reduced. It also opens up the possibility to dramatically improve the build schedule as well if the product we are offering is in stock.

Our Radiation Tolerant (RT) flow combines improved quality and reliability screening and qualification with radiation characterization and assurance. The combined flow yields a battery of tests that exceed the level of qualification and screening imposed on existing space qualified hermetic products. It will also include radiation characterization both for TID and SEE as well as lot qualification for TID. The work required is extensive and the unit pricing must reflect that. Even so, the benefits in performance, and reductions in size, weight and power compared to existing space qualified products coupled with the quality and radiation assurance will more than justify the cost and will enable future spacecraft to deliver higher performance at a lower total cost than ever before.

We fully recognize that not every mission will be able to accept PEM products. So we will continue to develop similar advanced products for use in hermetic packages where those previously mentioned packaging challenges prove manageable. We will continue to expand our partnership with our packaging partners to release both Radiation Tolerant (RT) as well as Radiation Hardened (RH) hermetic products.

In order to focus our effort on the products that will truly transform your future spacecraft, we would appreciate hearing from you. Please let us know what Linear Technology products would most dramatically affect SWAP and performance for your spacecraft. It could be small reductions multiplied by many uses in a spacecraft or products that integrate many functions and protection features into a single component used only in a few per spacecraft. Our future product development will be driven in large part by customer demand. Please let us know your vote for the products that would have the biggest benefit in your spacecraft by contacting us at LTSPACE@linear.com.

LTC Excellence