RAD-PAK® Technology Overview
Currently, RAD-PAK products are being used by over 100 space programs. Many different advanced products with many functions and different packages are available.
Some examples include:
- EEPROM 8Mb, 4Mb, 1 Mb
- SRAM 64Mb, 32Mb, 16Mb, 4Mb, 1Mb
- 16BIT A/D, Latchup Protected
- FIFO 16K x 9, 8K x 9
- DRAM 1Gb, 256Mb, 64Mb, 16Mb
- CCD Driver
- FPGA up to 50,000 gates, Latchup Protected
RAD-PAK has been proven effective in shielding semi-conductor chips against the hostile radiation environment encountered in space. Because of the shielding RAD-PAK provides, many of the commercial chips considered "soft” can now be used in applications that once required radiation hardened devices.
Some of the key advantages of the Rad-Pak product are:
- 10X Weight Reduction Impact
- Advanced Devices Available
- 100krad(Si) Minimum
- Best Price/Performance
- NASA Qualified
- 100% Screening
- Stock to 6 Months Availability
Modeling near Earth space environments
The space environment encountered by an Earth orbiting satellite contains many hazards, including, electrons, protons, heavy ions, neutrons, galactic cosmic rays, and more. As these particles come near the Earth, they are influenced by its magnetic field. As a result, electrons and protons are trapped in radiation belts known as the Van Allen Belts. Due to the solar cycle, these radiation belts are continuously changing and hence the radiation environment around the Earth is continuously changing. RAD-PAK technology, as developed by Maxwell Technologies Microelectronics, was designed to optimize shielding effectiveness for this continuously changing environment.
In modeling an environment so that RAD-PAK technology can be used, other considerations need to be examined. These considerations include the die level dose tolerance, satellite shielding, the satellite orbit and mission life. Dependent on the orbit, RAD-PAK technology along with satellite shielding can offer huge advantages over unprotected IC’s. This protection can greatly increase a "soft” ICs chances of remaining operational.
Maxwell Technologies Microelectronics uses Space Radiation 4.0 to do its radiation environmental analysis. Maxwell performs radiation transport analysis to design the RAD-PAK package to meet the radiation environment for the particular IC. In determining the amount of shielding required, the geometry of the spacecraft must be determined to find the available shielding to the unprotected die. If the environment exceeds the die level tolerance, then RAD-PAK is used to bring the radiation at the die level down to within tolerance.
Due to the complexity and volume of the calculations, it is not practical to present data for all possible orbits. However, to illustrate the effectiveness of RAD-PAK products, we have performed calculations for common satellite orbits through varying levels of shielding including RAD-PAK 1, 2, and 3. The units used in these calculations for shielding and radiation are converted into gm/cm2 of Al and rads(Si)/yr, respectfully, to represent commonly used units. A key aspect of RAD-PAK technology for shielding electrons is the use of high-Z materials. For the tight confines of a satellite, it has been shown that high-Z materials are significantly more effective at shielding the ionizing radiation found in space than low-Z materials. This has been shown with the CRRES experimental satellite flown in the early nineties.
As mentioned above, the effectiveness of RAD-PAK depends on the radiation environment. For this reason, Maxwell Technologies Microelectronics will advise each customer whether RAD-PAK is suitable for the conditions they require. Typically, it is heavier than a comparable ceramic part, however because of the benefits of RAD-PAK, more advanced components can be used. With more advanced components, fewer devices are required, saving both space and weight.