Re-flow Oven Controller Universal board Version 2.01

Having gone through several designs , i developed my own controller with a difference. the controller named Universal can accommodate two setups for the sensor as outlined below.

This board features:

ATMEGA328P processor clocked at 16Mhz

HD44780 16x2 LCD display

MAX31855 thermo-couple Sensor on board

Can be interfaced with a 2 button analogue keypad *(Default)

Can be interfaced with a 4 button digital keypad

Has provision for heartbeat led *(Default)

Transistor Buffered Buzzer output *(Default)

Power input protected with inline PTC Fuse and Crowbar diode.

Transistor Buffered SSR OUtput to drive Solid state Relay Module : 5V Drive

Serial Output with formatted csv data for monitoring on PC.

LCD Display

The LCD 16 characters by two lines display all the required information. These are explained as follows : Line 1 : Displays the Re-flow state together with the Temperature it needs to Reach. Line 2 : Displays the actual temperature being read from the sensor , the time count and the Soldering Profile.

The Temperature Sensor

As for the sensor, an independent supply of 3v3 is also included and adequate power supply filtering on the input channel of the probe is provided.

Power Supply Considerations

The boards accepts 9v to 24v input and is protected with an inline PolyFuse and a reverse polarity protection.

Serial Port

The Board has serial output (57600) . this is used to log and monitor activity and also to upload new firmware.

Keypads

The board can be configured to use one analogue line or else use three digital lines:

Single line Setup A1:

• Switch 1 controls the start - stop of the re-flow

• Switch 2 controls the solder profile.

Digital Setup

The board has provision with connector U2 to use Digital Line D3,D4,D5

Profiles

• Leaded solder - shown on LCD as SnPb as for (Sn63Pb37)

• Lead free - shown on LCD as SnAgCu as for (Sn96.5Ag3.0Cu0.5)

Re-flow Stages

The re-flow Controller performs the following stages :

Preheat – The first step is to increase the temperature from room temperature to 150 °C. The ramp up rate is 1 to 3°C per second.

Soak – The second step is used to activate the solder paste and allow the flux to clean the pads being soldered.

Re-flow – The third step is used to allow solder paste to reach it's melting point Known as the 'liquidous temperature' which is about 218 °C for lead free solder paste (Sn-Ag-Cu based).Here the solder joins the component to the board.

Cool – The Fourth step is the cooling down. this step is required so as the components are cooled down in order not to cause a thermal shock.

What you Get

The board can be supplied ready built or else supplied as a kit.

For the Assembled Version : Just connect a K-Type thermo-couple and a Solid State Relay and you are ready to Reflow SMD soldering.

For the Kit Version Just follow the printed circuit board legend and the guide sheet provided.

Sensor config Options set by jumper.

Default *

Clock : *A3 D13

Chip Select : *A2 D7

Data Line : *A0 D12

Supplied as :

Bare pcb kit : smd parts,connectors,programmed processor,pcb,lcd, misc semiconductors

Assembled pcb + lcd + ATMEGA328PU with pre loaded software.

Please Note : This Listing is for the controller Only.

To complete your project you will need the following

• Toaster Oven -220V
• SSR 5Volts in - 220v 15Amp
• Mini 12v Power supply
• K-Type thermo-couple not Supplied with assembled unit and kit !
• 5V Buzzer