What is it?

A compact temperature-controlled PCB hot plate for soldering and reflowing PCBs with solder paste

Why did you make it?

I wanted to get started with reflow soldering and join the surface mount technology squad without needing a bulky reflow oven or modified hot plate.

What makes it special?

It's the least bulky way possible to reflow, and it won't damage your electronic components like hot air might. It has two reflow profiles and a choice between 6 different temperatures. It's an open-source hardware project. It is optimized for low-temperature soldering paste. Bring your own 12V/5A power supply with barrel plug. It's like the movie Inception, except a PCB can reflow a PCB can reflow a PCB...

Feature list

• PCB size 100x100mm, heat plate size 81x69mm
• DC barrel plug (5.5x2.5mm), runs with 12V/5A (at least 5A) power supply
• inrush current limiter to protect power supply when capacitors are discharged
• input power filter for smooth current draw
• capacitor discharging resistors
• ATMEGA4809 microcontroller, can be re-programmed via UPDI header
• high power NMOS with gate driver circuit
• flyback diode connected to the heat plate
• AMS1117 LDO
• additional diodes for protection
• dual OMRON raised buttons
• power LED
• 0.91" OLED display
• LMT85 analog temperature sensor as main sensor

Includes:

• What you see in the photo
• Code is pre-programmed
• 1 3-pin header that can be push-fit into the UPDI holes for reprogramming
• 1 optional high-temperature diode that can be soldered on to support 24V power supplies (unsolder the old one at D2, make sure the line is in the same direction)

Does not include:

• 12V/5A power supply
• UPDI programmer

Recommended soldering paste:

Tin/Bismuth/Silver https://www.amazon.com/gp/product/B096BMCXHX/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Instructions:

• Connect a 12V/5A power supply with a matching barrel plug, or up to a 24V/5A power supply if you've changed to the optional diode.
• Choose a temperature using the two buttons and press both buttons to confirm
• Choose a reflow profile and press both buttons to confirm and move to the heating stage
• While heating, the display shows in order: Duty Cycle %, Sensed Temperature, and Target Temperature
• While heating, press any button to cancel heating

Discord link:

Join the open-source PCB hot plate community https://discord.gg/RD8kk6bk6f

Version history:

7/01/2023: V1.2, easier to push buttons and higher voltage capacitors, 24V modification possible