Best thermal cameras for electronics repair

What the camera needs to reveal on a circuit board

In electronics repair, a thermal camera is mainly used to find the faulty component quickly. A short on a supply rail, a failed decoupling capacitor, an overheating regulator, an integrated circuit drawing abnormal current or a resistive solder joint all dissipate heat. On a powered board, that component shows up warmer than its neighbours, sometimes by only a few degrees.

Thermography is also used to check a design’s heat dissipation: the temperature of a power transistor, the effectiveness of a heatsink, how heat spreads across an enclosed board. In every case the targets are tiny: an SMD package a few millimetres across, sometimes under a millimetre. It is the most demanding use in the catalog for spatial resolution and focus distance.

Getting the measurement conditions right

• Limit the current: to find a short, a bench power supply with current limiting lets you inject just enough energy to heat the fault without destroying other parts.
• Look early: heat spreads quickly through the board’s copper. The first seconds after power-up show the point of origin more clearly than the stabilised image.
• Steady the camera: at a few centimetres, the slightest movement takes the target out of frame or out of focus. A stand or an articulated arm makes all the difference.
• Watch for reflections: metal packages, tinned pads and shields reflect the heat of your hands and your work lamp.

For a detailed method, read thermal cameras for electronics repair.

Distance, target size and resolution

The typical situation used by the selector is an area of about 2 mm seen from 10 cm. Two conditions must be met. First, the camera must be able to focus that close. Many standard lenses do not go below 20 to 50 cm, and the selector excludes devices whose published minimum focus distance is too long. Second, the area resolved at that distance must stay smaller than the target.

Example: with a 256 × 192 sensor and a 50° field of view (IFOV about 3.4 mrad), one pixel covers 0.34 mm at 10 cm. The measurable area with our five-pixel margin is about 1.7 mm: a 2 mm component is only just measurable, a 1 mm 0402 part no longer is. That is where the macro lens comes in. It reduces the area covered by each pixel to a few tens of micrometres, but requires a precise working distance, often a few centimetres. It may also limit measurement range or accuracy, so check its datasheet. The selector only uses the macro when both its spot size and working distance are published, and when that distance matches yours within 20 %: a macro designed for 3 cm is not counted for work at 10 cm. To assess a device with its macro, enter its working distance in the selector.

What matters, and what matters less

• Minimum focus distance: a deal-breaker. A fixed-focus camera set for 50 cm only produces a blurred image at 10 cm, whatever its resolution.
• Macro lens and spot size: essential for components under 2 mm.
• Native resolution: the more real pixels, the more finely the target is covered. “Displayed” resolution produced by processing (super-resolution, interpolation) improves how the image looks, not the measurement of a small part. See super-resolution: what it really changes.
• Sensitivity: useful for faults that only heat up by one or two degrees.
• What matters less: high temperature range, ruggedness and long reach. A higher frame rate is still welcome to follow a fast rise at power-up.

Common pitfalls

Emissivity is the major pitfall in electronics. A black epoxy package emits well, but a tinned pad, a metal shield or a bare aluminium heatsink show a temperature far below reality and reflect their surroundings. A thin piece of high-emissivity tape (polyimide or matte black masking tape) placed on the area gives a more accurate reading. The second pitfall is jumping to conclusions: the hottest component is not always the culprit; it may simply dissipate a lot by design. Compare with a known-good board or with the schematic. See also why emissivity skews temperatures.

Phone attachment or standalone camera?

This is where smartphone modules make the most sense. Mounted on a stand above the board and connected to a phone or computer, they give a large image on a comfortable screen, and several accept a macro lens. Some high-end standalone models remain superior thanks to manual or motorised focus, dedicated macro optics and more complete analysis software. For the typical 10 cm distance and 2 mm target, no phone module in the current catalog is documented well enough to be ranked with confidence. Several still need checking, especially for minimum focus distance. This does not mean a phone module can never work: enter your actual distance in the selector and check the working distance of any macro lens before comparing scores.

What budget should you plan?

To find shorts on everyday boards, a module in the €€ band (€200 to €500) with close focus and, ideally, a macro is often enough. For a repair workshop or development work, the €€€ to €€€€ bands (€500 to €2,000) bring better native resolution, a quality macro and more complete software. The €€€€€ band covers research and detailed component characterisation. See the price ranges page.

Frequently asked questions

Can I find a short without a thermal camera?

Yes, with patience: resistance measurements, current injection and feeling for heat, isopropyl alcohol that evaporates faster on the hot spot, or freeze spray. The camera saves a lot of time and avoids touching a live board.

Do I really need a macro lens?

For components larger than 2 to 3 mm, a good standard lens with close focus may be enough. For small SMD packages and fine-pitch integrated circuits, a macro becomes essential.

Why does my component look cold when it is hot?

It is probably metallic or shiny, so it has low emissivity: the camera mostly measures a reflection of the surroundings. Apply a small piece of high-emissivity tape and measure on the tape.

Does super-resolution help in electronics?

It makes the image nicer to look at, but it creates no additional measurement. For a component smaller than the area actually resolved, only higher native resolution or a macro improves the measurement.