Rapid Prototypes That Survive the Real Environment
The fastest path from a sensor concept to a part you can trust is to build prototypes inside the same manufacturing cell that will eventually produce them — and to qualify those prototypes against the actual environment, not against a generic specification. Thermometrics Corporation operates a co-located prototype build shop and environmental qualification laboratory at our Northridge, California facility, allowing the engineering team to design, build, test, redesign, rebuild, and retest within a single program week.
A typical prototype timeline is two to four weeks from receipt of an approved drawing package to delivery of functional sensors. Where the application requires it, that delivery is preceded or followed by environmental qualification testing executed in our in-house laboratory, with photo-and-data documentation that customers routinely incorporate directly into their own design-review packages.
The laboratory supports cryogenic environments to the boiling point of liquid nitrogen (-196 °C), random and sine-on-random vibration profiles to several hundred Hz, pneumatic and hydraulic pressure to several thousand psi, and thermal cycling between -65 °C and +200 °C in air or inert atmosphere. Higher-energy or specialized environments (large-amplitude shock, salt fog, fungus, sand and dust, EMI) are routinely executed at accredited partner laboratories under our project management.
- Prototype builds in 2–4 weeks from approved drawings
- In-house cryogenic, vibration, pressure, and thermal-cycling test cells
- Customer-specified Acceptance Test Procedures (ATP) executed per signed plan
- MIL-STD-810, RTCA DO-160, and customer-bespoke standards supported
- Photo and data documentation included with every test report
- Iterative design-build-test-refine workflow inside a single facility
Build & Test Under One Roof
Iteration speed is the dominant determinant of program risk. When a prototype that fails a test cycle requires a re-engineering and re-build between facilities, weeks are spent moving information rather than improving the design. Our prototype shop and qualification lab share the same corridor — failed units are on a test engineer's bench the same hour they come out of a chamber, with the design engineer who scoped them already in the conversation.
Typical Test Matrix
Cryogenic: -196 °C immersion in LN₂
Vibration: Random & sine to ~500 Hz
Pressure: To several thousand psi proof & burst
Thermal Cycling: -65 °C to +200 °C
Standards: MIL-STD-810, RTCA DO-160, custom
Lead Time: 2–4 weeks prototype build
In-House Qualification Capabilities
The capabilities below are operated by Thermometrics test engineers in our own laboratory. Each capability is supported by calibrated reference instrumentation traceable to NIST and by procedures written into our AS9100D quality management system.
Cryogenic Immersion
Direct liquid-nitrogen immersion at -196 °C with multi-channel data acquisition. Plunge cells for response-time characterization, dwell tanks for soak testing, and instrumented dewars for thermal-gradient mapping. Common pass criteria include post-soak insulation resistance, post-cycle calibration drift, and structural integrity inspection. Sub-atmospheric LN₂ for setpoints below -196 °C available on request.
Vibration
Electrodynamic shaker for random, sine, and sine-on-random profiles. Capable of MIL-STD-810 Method 514 random vibration profiles and RTCA DO-160 Section 8 categories typical of commercial aviation. Accelerometers monitor input and response simultaneously; the unit under test is held in the customer-specified mounting fixture or in a representative interface fixture we machine in-house.
Pressure & Burst
Hydrostatic and pneumatic pressure testing for proof and burst evaluation. Manifold-controlled ramp rates with high-accuracy pressure transducer instrumentation. Hold tests with leak monitoring via differential pressure and helium mass-spectrometry. Common pass criteria: no leak, no permanent deformation, calibration within band post-test.
Thermal Cycling
Programmable environmental chambers performing temperature cycling between -65 °C and +200 °C. Profiles per MIL-STD-810 Method 503, RTCA DO-160 Section 5, or customer-bespoke. Continuous in-chamber resistance or thermocouple-output monitoring detects intermittent failures that bench testing alone would miss. Dwell, ramp-rate, and cycle-count tailored to the program.
Thermal Shock
Two-zone air-to-air and liquid-to-liquid shock test with transfer times below 10 seconds for fast-quench thermal-stress characterization. Used to surface bonding-line defects, hermetic-seal latent failures, and thermal-mismatch cracking in mixed-material sensor assemblies.
Insulation & Hi-Pot
Insulation resistance measurement at multiple DC voltages (typically 50 V, 100 V, 500 V); dielectric withstand (hi-pot) at AC and DC test voltages to several kV. Integrated into thermal-cycle and post-environmental test sequences for hermetic seal and lead-wire insulation integrity.
ATPs Tailored to Your Specification
An Acceptance Test Procedure (ATP) is the contractual document that defines what tests will be performed, in what sequence, with what instrumentation, and against what pass/fail criteria. The ATP is the lingua franca between our test engineers and your design-assurance organization — the document that lets two parties agree, in advance, what a successful qualification looks like.
For programs without an existing ATP we draft one. For programs that bring their own ATP (typical for aerospace, defense, and regulated industrial primes) we execute against the customer's document verbatim and append our test data, photos, instrument calibration certificates, and signed pass/fail rationale. We are comfortable working under government contract terms, DPAS-rated PO, ITAR program controls, and customer-quality-clause flow-downs.
Design – Build – Test – Refine
The fastest way to converge on a sensor design that survives the application is to put real hardware in front of the real (or representative) environment as early and as often as possible. Our prototyping workflow is built around tight, instrumented loops between the engineering bench and the test laboratory.
Design
Engineering scopes the configuration against requirements, drafts source-controlled drawings, and freezes a build-level revision. For very early design loops, an interim sketch and a verbal materials call-out can replace formal drawings — provided the team is comfortable with the documentation trade-off.
Build
Prototype technicians fabricate sensors in the same cell that will produce serial parts. Build records are captured (operator, date, lot of incoming materials, any deviations). Sensors are tagged with a serialized prototype identifier that ties every downstream test record back to a specific physical unit.
Test
Built sensors enter the qualification laboratory and run the planned environmental sequence under continuous instrumentation. Failures, anomalies, and unexpected behaviors are photographed, captured in test logs, and brought to the engineering team the same day. Successful units are calibrated and returned to the customer for their own bench evaluation.
Refine
Engineering reviews the test data, identifies the failure mode (if any), and revises the design — material change, dimensional change, assembly-process change, or test-condition reconsideration. Drawing revision is captured. Loop returns to step 01. Programs typically converge in two or three iterations.
Why Iteration Matters More Than Theory
Sensor failures rarely come from the obvious failure mode you designed against. They come from the second-order interaction nobody thought to model — a vibration mode that couples through a mounting boss into a lead-wire strain relief, or a thermal-cycle dwell that exposes a moisture-ingress path that hydrostatic testing missed. Iterative testing is what surfaces these. A program that depends on getting it right the first time depends on being lucky.
- Most programs converge in 2–3 design iterations
- Each iteration: 2–4 weeks build, 1–3 weeks test
- Failure-mode notes carried forward across iterations
- Final qualified design promoted to production with full lineage
What the Test Report Contains
A qualification test that is not documented to an auditor's satisfaction is a qualification test that has to be re-run. Our test reports are produced as serialized, revision-controlled deliverables under our QMS — designed to be inserted directly into your design-review or product-data package.
| Section | Contents | Purpose |
|---|---|---|
| 1. Cover & Approvals | Report number, revision, customer PO, signature block for test engineer and quality manager | Establishes traceability and chain of accountability for the report. |
| 2. Article Description | Part number, revision, serial numbers of every UUT, photo of as-received condition | Identifies exactly what was tested, eliminating ambiguity in later audit. |
| 3. Reference Documents | Drawing package revision, controlling specification, customer ATP revision, applicable standards (MIL-STD, DO-160 sections, etc.) | Anchors the test to the contractually agreed requirement set. |
| 4. Test Sequence | Tabulated test order, dwell durations, ramp rates, cycle counts, environmental setpoints | Documents exactly what was done in exactly what order. |
| 5. Test Equipment | Asset tags of every chamber, shaker, transducer, pressure gauge, and DAQ channel; calibration certificate dates | Provides equipment traceability to NIST. |
| 6. Pre-Test Baseline | Pre-test calibration, dimensional inspection, insulation resistance, electrical-continuity check | Establishes the starting condition of each UUT. |
| 7. Test Data | Time-stamped continuous data files, photographs at key milestones, anomaly logs | The empirical record. Raw data is preserved for re-analysis. |
| 8. Post-Test Inspection | Post-test calibration, dimensional inspection, insulation resistance, visual inspection, delta-from-baseline tabulation | Quantifies any change in the UUT caused by the environment. |
| 9. Pass / Fail Determination | UUT-by-UUT pass/fail against ATP criteria; rationale in writing; non-conformance reports as needed | Definitive conclusion against the contractual acceptance criteria. |
| 10. Appendices | Calibration certificates, raw data files (CSV / TDMS), photographs, supplier traceability records | Provides the audit-ready evidence trail at the document level. |
Qualification Standards We Work To
The standards below describe the environmental test methods our laboratory and our qualified test partners are most often asked to execute. Where a customer brings a bespoke environmental specification, we map it to the applicable standardized methods and report against the customer's language.
MIL-STD-810
Department of Defense Test Method Standard for Environmental Engineering Considerations. Our laboratory routinely executes Method 501 (high temperature), 502 (low temperature), 503 (thermal shock), 507 (humidity), 514 (vibration), 516 (shock), and 520 (combined environments — temperature, humidity, vibration, and altitude).
RTCA DO-160
RTCA / EUROCAE environmental conditions and test procedures for airborne equipment. Common section coverage includes Section 4 (temperature and altitude), Section 5 (temperature variation), Section 6 (humidity), Section 7 (operational shock and crash safety), Section 8 (vibration), and Section 16 (power input).
SAE AS50881 / J1455
Aerospace and ground-vehicle wiring and environmental standards routinely referenced in custom temperature-sensor programs. Particularly relevant where sensor lead-wire systems and terminations must qualify alongside the sensing element itself.
IEC 60068 Series
International standard environmental testing series widely used outside the United States and increasingly in U.S. industrial work. Tests we routinely execute include IEC 60068-2-1 (cold), 60068-2-2 (dry heat), 60068-2-6 (sinusoidal vibration), 60068-2-14 (change of temperature), and 60068-2-30 (damp heat cyclic).
IEC 60751 & IEC 60584
Defining tolerance and characteristic standards for industrial platinum RTDs (IEC 60751) and thermocouples (IEC 60584). Our qualification programs verify conformance with these standards as the baseline accuracy and stability requirement, on top of which environmental tests are layered.
Customer-Specific Standards
Prime-contractor and OEM environmental specifications (Boeing D-, Lockheed, Pratt & Whitney, GE Aviation, Rolls-Royce, large industrial OEMs, DOE national laboratories). Where the customer's standard is not publicly available, we work under appropriate licensing and program-access controls.
Representative Sequences We Execute Routinely
The sequences below are representative envelopes assembled from customer programs in aerospace, energy, and laboratory metrology. Every sequence is tailored to the specific application — these examples set expectations for what a qualification campaign for a comparable program typically contains.
Aerospace Engine Sensor
Pre-test baseline (cal + insulation resistance) → thermal shock (10 cycles, -55 °C ↔ +200 °C) → random vibration (MIL-STD-810 Method 514, three-axis, 1 hour per axis) → high-temperature dwell (1000 hours at peak operating temperature) → post-test baseline → calibration drift evaluation. Typical campaign duration: 8–12 weeks.
Avionics RTD (DO-160)
Pre-test baseline → DO-160 Section 4 (Temperature & Altitude, Category D2) → Section 5 (Temperature Variation) → Section 6 (Humidity, Category A) → Section 8 (Vibration, Category S Curve M) → Section 7 (Operational Shock) → post-test baseline. Continuous resistance monitoring through chamber pass-through. Typical campaign duration: 6–10 weeks.
Cryogenic Probe Qualification
Pre-test baseline → LN₂ plunge (-196 °C) response-time characterization → thermal cycle (-196 °C to room, 100 cycles, ramp ≤5 minutes) → hold at -196 °C (200 hours soak) → post-soak insulation resistance → post-test baseline. Particular attention to platinum-element bond integrity and seal helium-leak rate. Typical campaign duration: 4–6 weeks.
Downhole / High-Pressure Sensor
Pre-test baseline → hydrostatic proof pressure (1.5× MAWP, 1 hour hold) → hydrostatic burst-margin (to 2.5× MAWP, no failure) → thermal cycle at operating pressure → vibration with mud-pump representative spectrum → post-test calibration. Typical campaign duration: 6–8 weeks.
Industrial / Pharma RTD
Pre-test baseline → IEC 60068-2-30 damp heat cyclic (six cycles, 25 ↔ 55 °C, 95% RH) → IEC 60068-2-6 sinusoidal vibration (10–500 Hz sweep) → IEC 60068-2-14 thermal cycling → IP-rating ingress verification → post-test calibration drift < Class A tolerance. Typical campaign duration: 4–6 weeks.
Reliability / HALT Programs
Highly Accelerated Life Test campaigns combining stepped thermal stress, vibration stress, and combined thermal + vibration stress to surface latent failure modes faster than calendar time allows. Useful early in development to identify the weakest design element before customer-facing qualification begins.
From PO to Hardware in Hand
The breakdown below reflects what customers typically experience for a representative prototype-plus-environmental-qualification program. Where the drawing package is already mature and the test sequence is mainstream, the schedule compresses to its lower bound; where the environmental matrix is severe or the design space is open, expect the upper bound.
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