Modulated thermography is a non-destructive fault isolation technique that locates hotspots caused by shorts, latch-up, and abnormal power dissipation in integrated circuits, packages, and circuit boards. Power to the device is modulated while a mid-wave infrared (MWIR) thermal camera images it, separating heat generated by the failure from the thermal background.
Modulated thermography is also referred to as modulated thermal imaging, thermal hotspot detection, and thermal emission analysis.
Failures Modulated Thermography Localizes
- Metal-to-metal shorts
- Fused silicon
- Circuits in latch-up
- Gross electrical shorts
- Abnormal power dissipation at the die, package, or board level
How Modulated Thermography Works
Power to the device under test (DUT) is switched between on and off states while the MWIR camera captures thermal images synchronized to the modulation. Comparing and averaging the powered and unpowered images removes the static thermal background and emphasizes heat generated by the device, improving hotspot contrast over a single static thermal image. Silicon is largely transparent in the MWIR band, so analysis can also be performed through the backside of the die.
Modulated Thermography vs. Lock-in Thermography
Lock-in thermography (LIT) adds phase-sensitive demodulation at the modulation frequency, which further increases sensitivity and provides phase data that can estimate the depth of a buried heat source. Modulated thermography is well suited to shorts, latch-up, and other failures that dissipate enough power to produce a resolvable hotspot. For very low-power resistive defects, laser-based techniques such as XIVA™ and lock-in XIVA™ are typically more sensitive, and our engineers select the technique that best fits the failure signature.
When to Use Modulated Thermography
Modulated thermography is often an early step in the fault isolation workflow for shorts and excessive supply current. For failures that dissipate sufficient power, it can localize the hotspot at the package or board level before destructive preparation. It complements photon emission microscopy, which detects light-emitting defects, and XIVA™, which localizes resistive defects with laser stimulation.
Turnaround and Deliverables
Typical turnaround for modulated thermography is 3 to 5 days, depending on device complexity and the sample preparation required. Results are documented with annotated hotspot images overlaid on the device in an engineering report.
Related Services
- Semiconductor Fault Isolation (all techniques)
- Photon Emission Microscopy
- Externally Induced Voltage Alteration (XIVA™)
- Scanning Acoustic Microscopy (SAM)
- Cross-Sectioning Services
Frequently Asked Questions
What is modulated thermography?
Modulated thermography is a thermal imaging technique that switches power to a device on and off while an infrared camera captures synchronized images, isolating heat from shorts and abnormal power dissipation against the thermal background.
How does modulated thermography differ from lock-in thermography?
Both modulate device power. Lock-in thermography also applies phase-sensitive demodulation, giving higher sensitivity and phase data for depth estimation. Modulated thermography is effective for shorts, latch-up, and failures with sufficient power dissipation.
What failures is modulated thermography best for?
Metal-to-metal shorts, gross electrical shorts, latch-up, fused silicon, and other failures that produce a measurable hotspot under power.
How long does modulated thermography take?
Typical turnaround is 3 to 5 days, depending on device complexity and the sample preparation required.
Request Modulated Thermography
Watson Analytical is an ISO 9001:2015 certified, ITAR-registered failure analysis laboratory in San Diego, California, serving semiconductor, defense, space, biomedical, and litigation customers. Contact us to discuss your failure and request a quote.