1 Abstract

Historically, satellite programs have used space grade, hermetically sealed, QML-V qualified components for enhanced reliability and radiation hardness. With the emergence continued growth in constellation and low-earth orbit satellite launches for new commercial and government programs, there is a growing need for smaller components that can meet strict budgets. As a result, there has been more interest in using plastic encapsulated microcircuits (PEM) in space for a variety of reasons. PEMs become more attractive because leading edge products are not available as space qualified products and PEMs generally have smaller footprints and are lighter than the ceramic packages used in space qualified products. It has been recognized that there is a quality and reliability risk in using commercial-off the shelf (COTS) products and some space programs have been investigating using automotive grade AEC-Q100 products with more stringent qualification requirements. However, the extra qualification steps in Q100 parts do not meet all the requirements of a space application, even for those space applications with reduced requirements. For instance, commercial low earth orbit (LEO) applications with a projected three year life still have to meet radiation goals that many PEM products do not survive. One of the biggest challenges for a satellite program is finding and then testing those products that meet the radiation goals.

Although radiation performance may be biggest obstacle to using some COTS or automotive products in space, there are a number of other risks and factors to consider, such as tin whiskers, copper bond wires, rated temperature range, and package outgassing. Finding a device that can withstand the harsh environments of space can prove to be time consuming and challenging.

In addition to Texas Instruments' full line of rad-hard QML-V products for normal and high risk space missions, TI has introduced the rad-tolerant Space Enhanced Plastic (Space EP) product family in PEM packaging to lower the risk of using PEMs for missions with reduced requirements. The Space EP products have the following features:

• Single Event Latch-up (SEL) immune to 43 MeV-cm²/mg with some components such as power management having characterized additional destructive single event effects and single event transients. Each product is tested at maximum operating voltage and 125°C.
• ELDRS-free to 30 to 50 krad(Si). Every bipolar and BiCMOS product goes through ELDRS characterization at low dose rate (LDR) of 10 mrad(Si)/s.
• Radiation lot acceptance testing (RLAT) from 20 to 50 krad(Si). Every wafer lot is tested and qualified to 20 krad(Si) with an RLAT report available. Devices with higher TID characterization are typically assured with the same RLAT level.
• Some components also having Neutron Displacement Damage reports
• Military temperature range: –55°C to +125°C.
• No copper bond wires. All products have gold bond wires.
• No matte tin. Lead finish is NiPdAu or some other finish that does not have pure Sn.
• Enhanced mold compound for low outgassing.
• Extended qualification of each assembly lot including HAST and temperature cycling.
• 100% temperature cycling. Every unit receives temperature cycling or equivalent.
• Single production flow. One wafer fab and assembly site to minimize lot-to-lot variation.
• Long product life cycles.
• Each product has its own Vendor Item Drawing (VID) on DLA website.

The risks of using PEMs in space and how TI's Space EP products address these risks are discussed in this application note.