Reflow Micro Table is a compact Bluetooth-controlled reflow table with an 80×70 mm working area. It is built for those who assemble PCBs from time to time and do not want a bulky professional-grade machine taking up desk space.
It runs from a 100–140 W USB PD charger, is controlled via a web browser on desktop or mobile, and closes into a compact case for storage when the job is done.
Why This Project
Compared with existing compact hotplates, the 80×70 mm working area is substantially larger than the typical 50×50 mm. The other key difference is the UI: profile setup and process monitoring happen in a browser over Bluetooth, which is far more practical than a minimal on-device interface.
A secondary goal was to show that the technologies behind modern electronics are accessible today. Even at home, it is now possible to build complex devices that match factory-made products and, in some cases, go beyond them.
Typical use cases:
- reflow soldering with LTS paste
- bottom preheating for hot-air work
- reflow soldering with leaded paste using the MCH-based head
- other heating tasks, such as drying parts
The MCPCB-based head reaches up to 180°C. The MCH-based head reaches up to 250°C. Component cost is about $85 with the MCPCB heater and about $105 with the MCH heater.
Design Decisions
Power
Starting constraints:
- An 80×70 mm working area requires significantly more power than a 50×50 mm one.
- It is not always possible to perfectly match heater resistance — you have to work with available options.
- Heater resistance at room temperature versus maximum temperature differs by roughly 2x.
How it was solved:
- 140 W USB PD chargers were chosen as the power source. They are widely available, and single-port models cost as little as $25.
- Since there was no good open-source USB PD support available, a separate project was created: pdsink.
- Dynamic PD profile switching was implemented: a cold heater has too low resistance to immediately apply maximum voltage safely.
The table prefers a PPS profile with voltage regulation. If the required voltage cannot be reached via PPS, it goes up to Fixed 28 V with PWM. Once PD 3.2 chargers with mandatory AVS profile support arrive — expected by the end of 2026 — PWM will no longer be needed.
Temperature Sensing
Rather than a separate temperature sensor, the table calculates temperature from the heater's own TCR (temperature coefficient of resistance). This significantly simplifies both the hardware and the case — an important factor for a DIY build. After two-point calibration, accuracy is within a few degrees.
Cost
Total component cost is $85–105, depending on the heater type — competitive with commercial devices of similar class, while offering roughly 2× the working area and significantly more flexible control.
If building a few units for yourself and friends, the effective per-unit cost drops by $40–50, since most components come in quantities that cover several builds.
The swappable head design adds some complexity, but it was the right call during early development when too many parameters were still uncertain. The result is good enough that further optimization is not necessary.
Heating Profiles
I have no production PCB assembly experience, so the profiles were developed from whatever information I could find. Fortunately, staying away from RoHS paste gives a comfortable margin for error. Due to limited power headroom at this plate size, the leaded profile had to be stretched, though the goal was to stay within the JEDEC limit of 60 seconds in the liquid phase.
One thing to keep in mind with bottom heating: the temperature difference between the heater and the top surface of the board is around 20°C. Heavy boards with internal copper layers can lag noticeably during ramp-up. As visible in the video, the table handles even this worst case successfully.
If you have experience with reflow profiles and see something to improve — write me please, or open an issue in the project tracker. Feedback is very welcome.
Browser Control
Browser-based control might seem like overengineering, but in practice, it adds no friction and simplifies everything else. The web app is a PWA: it works offline and can be installed as a regular app on any device.
This allowed the device itself to have a single button, which simplified both the circuit and the case. If you only use one profile, the button alone is enough to start a run — no app required.
One known limitation: iOS does not expose Web Bluetooth to the browser. A Wi-Fi fallback is a possible future improvement.
Self-Assembly
As visible in the video, the board overhangs the table edge during the build. It is not good practice. The reason: the goal was to verify that the table can reflow its own main PCB — a self-assembly proof of concept.
