Background
The extreme operating conditions of the space environment combined with lack of access for repairs and zero tolerance for failure necessitate intensive qualification of electronic parts used in space missions. Mini-Circuits has a successful track record of screening components for space applications, and our experience in this area has led to robust testing and qualification programs for the parts we supply for these systems.
Qualification requirements for space applications vary by program, materials and component type. Mini-Circuits offers a wide variety of hi-rel, ceramic components capable of meeting space level screening requirements. These include our extensive line of LTCC filters and diplexers, couplers, splitter/combiners and baluns, as well as a broad selection of amplifiers, mixers, limiters, and attenuators utilizing our hermetic LTCC packaging platform. This article will present examples or “case studies” of components supplied for space systems and describe typical qualification processes used to screen each of these product groups for space-borne systems. These examples highlight Mini-Circuits’ advanced capabilities in meeting qualification requirements to ensure high reliability for space missions, but they are by no means an exhaustive representation of our capabilities. We invite you to contact our applications team (apps@minicircuits.com) to discuss the specific requirements of your program.
1. LTCC Passives
Mini-Circuits’ LTCC passive components utilize rugged, multi-layer ceramic construction to achieve both extremely tiny size and outstanding reliability in harsh environments, making them excellent candidates for hi-rel applications. Our line of LTCC products includes an extensive variety of filters (high-pass, low-pass and band-pass), diplexers, couplers, splitter/combiners, 90° hybrids, and balun transformers, all available for space-level screening. This section will present a case study of the qualification process for an LTCC low pass filter to meet screening requirements for a particular space-borne system.
Space Level Screening of an LTCC Low Pass Filter
The LTCC filter screened in this case is a modification of standard model LFCN-8400+. This is a 7 section filter with a passband from DC to 8400 MHz and RF input power handling up to 8W. The unit comes housed in a 1206 ceramic package with an operating temperature rating from -55°C to +100˚C.
Figure 1: LFCN-8400+ LTCC Low Pass Filter with DC−8400 MHz passband and 8W power handling
Beyond the standard electrical and environmental ratings of the part, the special model satisfies a series of special screening requirements defined by a particular space flight program. The requirements include a material restriction that the unit terminations be constructed with tin-lead finish, with a maximum tin content of 97%. This is a standard requirement to prevent tin whisker growth. The special part also satisfies a date code restriction that shipped parts may be from a maximum of two lot date codes. If parts from two lots are shipped, one lot must be from new production and both lots must have passed screening independently.
Destructive Physical Analysis (DPA) is required on sample units from lots used for production to verify construction and termination composition. Units must also undergo a rigorous program of reliability testing including real time radiographic inspection in three views. The full qualification process performed to meet the program requirements is summarized below.
Qualification Process
Destructive Physical Analysis (DPA)
Prior to starting reliability testing, DPA is performed on three randomly selected sample units to verify the construction and termination composition on the lot to be used for production. MIL-STD-1580B is used to establish a general process for performing DPA on the units under test, but because pass/fail criteria for LTCC units are not defined by the standard, it is used as a guideline, and the units under test are compared to determine if there are any apparent abnormalities. Photographs from external and internal examination of the sectioned devices are shown in Figure 2 and Figure 3. The DPA pass/fail criteria are summarized in Table 1.
Reliability Testing
Following DPA, reliability testing consists of testing at 100% (Group A) and small sample testing (Group B) for a number of parameters summarized in Table 1.
| DPA | |||||
| Test | Condition(s) | Duration or Cycles | Reference | Sample size | Pass/Fail Criteria |
| DPA | Sample units sectioned along 2 planes (parallel and transverse) | – | MIL-STD-1580B Para. 14.1.1.1 Para. 14.1.1.3 | 3 units | a) External visual __inspection b) Prohibited materials __analysis of external __surfaces c) Internal visual __inspection of __sectioned devices |
| GROUP A – 100% Screening | |||||
| Test | Condition(s) | Duration or Cycles | Reference | Sample size | Pass/Fail Criteria |
| Thermal Shock | −55/+125°C | 10 cycles, 10 minutes | MIL-STD-202, Method 107 | 100% | Pass electrical |
| Bake-In | 24 hr. stabilization bake exposure at +100°C | 24 hr. | QCP-06-21 | 100% | Pass electrical |
| Real Time Radiographic Inspection | 3 views | – | MIL-STD-202 Method 209 | 100% | Pass visual |
| Final Visual and Mechanical Inspection | 10x magnification; 5 units inspected for dimension | – | – | 100% | External visual |
Table 1 (continued): Screening process summary for LTCC low pass filter (continued)
| GROUP B – Sample Screening | |||||
| Test | Condition(s) | Duration or Cycles | Reference | Sample size | Pass/Fail Criteria |
| Humidity | +85°C and +85RH, 1.3VDC ±0.25VDC test voltage applied | 240 hr. | – | 12 units | a) Pass electrical b) Visual inspection |
| Destructive Electrical Testing | Standard Electrical Measurements @+25°C, −55°C, and +100°C; samples soldered on PCB | – | – | 10 units | Pass electrical at +25°C; Summary data provided for all testing |
| Solderability | Units soldered on test board and inspected per IPC-A-610 | – | MIL-STD-202 Method 208 | 5 units | Meet requirements of MIL-STD-202 |
| Leach Resistance | Immersion in +260°C solder | 10 sec. | MIL-STD-202 | 3 units | a) Visual inspection b) Electrical test a) Bubble test |
| Terminal Strength | Push force of 0.5mm/s applied to samples soldered to test board | Until electrode pads are peeled off or ceramic is broken | MIL-STD-202 Method 211 | 3 units | 1 kg minimum solder strength |
Figure 4: Environmental testing in progress at Mini-Circuits laboratory in Brooklyn, New York
Qualification Flow
2. Hi-Rel Ceramic Packaging Platform for Amplifiers, Attenuators, Limiters and Mixers
Mini-Circuits has highly sophisticated systems and processes for ultra-high reliability ceramic, hermetically sealed packaging which is adaptable to a wide range of components including amplifiers (CMA-series), attenuators (RCAT-series), limiters (CLM-series) and mixers (MAC- and MRA-series). Utilizing LTCC ceramics, multilayer distributed circuitry, and automated processing, our flexible platform is suitable for integration and designs employing mixed technologies.
For example, Mini-Circuits’ MAC-series of hi-rel mixers incorporate diode quads utilizing semiconductor IC technology on GaAs wire-bonded to baluns embedded in an LTCC multi-layer substrate (Figure 7). The diode quads are then hermetically sealed in a controlled nitrogen atmosphere with gold-plated covers and eutectic AuSn solder. The same packaging platform is adapted to realize ultra-high reliability amplifiers, attenuators, and limiters as well.
This packaging platform provides advantages of very low parasitics and thermal impedance, very wide operating temperature range, and outstanding reliability in extreme environments. All Mini-Circuits’ hi-rel ceramic components are qualified to meet a whole battery of reliability standards shown in Table 2. These hermetic LTCC components are capable of meeting additional space level screening requirements and are available for screening. A case study of a ceramic, hermetic amplifier screened for a particular space flight program is presented in the next section.
Case Study: CMA-Series Hi-Rel Ceramic Amplifier
Mini-Circuits’ CMA-series of hi-rel ceramic amplifiers comprises a selection of standard catalog models with various combinations of performance parameters to meet different system requirements. All models utilize ceramic, hermetically sealed, nitrogen filled packaging to achieve outstanding reliability, operating temperature range from -55 to +105˚C, low inductance, and excellent reliability.
Figure 6: CMA-545+ ceramic, hermetically sealed, nitrogen-filled SMT Low Noise Amplifier with wideband performance from 50 MHz to 6 GHz and typ. 0.8 dB noise figure
The screening process for the special model consists of testing in three groups as summarized in Table 3 below:
Qualification Flow
Further Capabilities
The qualification processes presented in this article meet the requirements for upscreened components used in two particular space flight missions and are merely examples of Mini-Circuits capabilites. Requirements vary widely depending on many factors including the component type, materials, and other details specific to each flight program. Mini-Circuits tailors each upscreening to your mission’s unique requirements.
Beyond the two examples shown above, most of our catalog and custom products can be upscreened in-house for MIL Standard or equivalent using EEE-INST-002 compliant workflows in as little as 90 days. Our in-house screening reduces costs and accelerates your project timeline.
| Technology | Products | Standard |
| Core & Wire | Transformers | MIL-STD-981 for Family 11 |
| Power Dividers | ||
| Couplers | ||
| LTCC | Any LTCC component in the MCL catalog | Based on MIL-STD-202 with applicable test methods |
| Bare Die (Active & Passive) | Any die component in the MCL catalog | MIL-PRF-38534 Appendix C |
| Non-hermetic SMT products | Frequency Multipliers | MIL-PRF-38534 Appendix D |
| Power Dividers | ||
| Lumped Filters |
Standard Capabilities: Burn-in, thermal shock, vibration*, radiographic inspection*, destructive physical analysis (DPA)*, mechanical shock, hermeticity, outgassing requirements, residual gas analysis, and hydrogen poisoning susceptibility with accompanying acceptance test procedure (ATP).
In addition to our standard capabilities, Mini-Circuits’ space specialists on the applications support team can develop custom solutions for nearly any project. Mini-Circuits has a long history of space-level screening and testing servicing some of the earliest government space missions all the way through to the modern independent enterprises, and we’ll be happy to help you with your next project too.
*While Mini-Circuits performs most of its testing and upscreening in-house, we use specialist partners for a limited selection of tests.
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