reflowoven

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ESTechnical Desktop Reflow Oven T962A

Reflow Controller hardware v4

Thank you for your purchase of ESTechnical products. If you have any questions or comments please let us know, we are always keen to hear feedback about our products.

Precautions

ESTechnical accept no responsibility or liability for personal injury or damage to property – Perform testing on waste boards until you are confident the settings are correct for your oven, boards and parts density etc.

Place the reflow oven on a hard, level and heat resistant surface. Do not cover any holes in the oven housing – the airflow is necessary, damage to the oven and/or your PCBs will result if airflow is impeded.

Always allow the oven to cool to below 50 degrees (as reported on the display) before stopping the cycle or attempting to remove the boards from the drawer. Do not stop a reflow cycle and begin another without first allowing the oven to cool to near ambient air temperature.

Never start a reflow cycle with hot PCB(s) - allow to cool first.

Ensure adequate ventilation in the work area, air extraction is essential if working in a confined space.

Place boards to be soldered centrally in the drawer of the oven. If a small board is being soldered, it is best to position this below the thermocouple towards the front of the oven. This will provide the most accurate temperature control. Always ensure there is PCB below the oven thermocouple.

ESTechnical Reflow Oven Controller Operating Instructions

Caution

ESTechnical accept no responsibility or liability for personal injury or damage to property – it is the user's responsibility to correctly carry out installation and confirm the correct operation of the oven once installed.
Initial Set Up
  • Place the Reflow Oven on a hard, level, heat resistant surface
  • Attach the power cable to the reflow oven and plug in to a power outlet
  • Ensure none of the grilles on any panel are covered
Overview of Operation
Initial Set Up for new PCB designs
  • Prepare one or more test PCBs with a thermocouple attached
  • Load the default profile settings
  • Perform a test reflow cycle and observe the board temperature
  • Adjust the cycle settings in small increments and repeat the test cycle (with oven and PCB starting from near ambient temperature for every test) until the profile meets the needs of the solder paste and components used on your PCB(s)
  • Save these profile settings and make a note of the profile number in your project documentation for the PCB
Production of PCBs

Once you have set up a reflow profile for your PCB design:

  • Prepare PCBs with solder paste and components
  • Select the correct profile for the board design
  • Place PCB(s) in the reflow oven drawer
  • Run the cycle
  • Remove soldered PCB(s) once the oven has cooled
  • Repeat as needed

Navigate the menu using the keypad keys < & > to move through the menu items, press Ok to select a menu item. Pressing Back will return you to the previous level of the menu.

The menu is organised as follows:

Menu layout

  • Start Cycle
  • Edit Profile
    • Ramp up rate
    • Soak temp
    • Soak time
    • Peak temp
    • Peak time
    • Ramp down rate
  • Load Profile
    • Choose profile number
  • Save Profile
    • Choose profile number
  • Fan Settings
    • Idle speed
    • Save
  • Factory Reset
Reflow Profile Testing

The ESTechnical Reflow Oven Controller is equipped to make setting up reflow profiles easy – it is essential to carry out this testing correctly to ensure correct profile settings are used for your board(s).

Profile testing should be carried out for each design of board to be soldered.

To carry out profile testing, you will require a test PCB, kapton tape and heatsink compound.

Test PCB, kapton tape, heatsink paste and thermocouple

Decide where to place the thermocouple. Where you place the thermocouple on the PCB depends largely on the design. Densely populated areas or areas with large copper fills are a good choice for initial testing. Other areas of the board (for example, the top of tall parts) should also be measured once a suitable reflow profile has been set up to ensure the peak temperature is not exceeding the manufacturer's stated limits.

Small boards with few parts are often easy to profile correctly with no parts present, as the parts comprise a very small amount of the overall mass of the board. More densely populated boards may require further adjustments to the profile to adequately reflow all solder joints. Further testing is advised to ensure safe margins are kept from the maximum temperature specified for the most sensitive parts.

Secure the thermocouple cable with kapton tape while holding the tip in the correct location. Ensure the cable is well stuck down to provide some strain relief to prevent the tip of the thermocouple moving. It can help to strip back some of the outer layer of thermocouple sleeve.

Stick down the thermocouple cable securely with the tip held in the correct location

Apply heat sink paste to the tip of the thermocouple. Only apply a very small amount to ensure good thermal coupling between the PCB and the tip.

Apply heatsink compound to the thermocouple tip

Apply a thin strip of kapton tape over the thermocouple wires, very close to but not touching the tip of the thermocouple. Ensure this is well stuck down and the tip is making good contact with the PCB.

Apply more kapton tape to ensure good contact between the thermocouple tip and the PCB

Place the prepared PCB in the reflow oven, route the thermocouple cable out of the drawer at one side and fully close the drawer. Ensure the PCB is placed underneath the thermocouple mounted in the front of the oven. Plug the thermocouple into the thermocouple socket on the side of the reflow oven.

Run a test cycle and observe the temperature profile of the PCB. Make adjustments as necessary to the profile settings after each test profile, repeat until the profile temperature measured on the board is suitable for your parts and solder paste recommendations. Ensure the maximum temperature for the most sensitive part(s) are not exceeded.

Profile testing can be carried out by carefully watching the temperature reported for the PCB thermocouple, or by logging the data via the USB port and using the ESTechnical reflowViewer software (see below). Alternatively it is possible to use an external thermocouple meter to monitor the PCB temperature. Adjustments should be made to the profile settings based on the observed temperature of the PCB.

Ideal Fan idle speed Adjustment

If the PCB temperature does not closely follow the profile temperature settings, consider carrying out Fan Idle Speed Adjustment procedure.
Data Logging – ReflowViewer Software

ETechnical provide a simple live data graphing application for use with the reflow oven, this aids adjusting profile settings and helps reduce the number test cycles performed for each design. The software allows easy adjustment of the reflow profile settings stored in the oven controller.

For more information, see https://github.com/estechnical/reflowViewer

Operating Instructions
Starting a reflow cycle

Navigate to Cycle start in the menu and press OK. The controller will perform the cycle using the current cycle settings.

Stopping a cycle

Should you need to abort a reflow cycle, press the S key. The oven will move into the Cool down state. Observe the temperature on the display before attempting to open the drawer or remove boards.

Saving an edited profile

To save a profile navigate to Save Profile and press OK. Choose a profile number to save (by default all 30 profiles are the same, the user can save to any of these profiles) and then press OK. The profile is now saved in the chosen profile number.

Please note that any previous settings in the profile number you save to will be overwritten with the new settings.

Loading a saved reflow profile

Navigate to Load Profile and press OK, using the < and > keys, choose the profile number you wish to load. Press OK, the reflow profile settings will be loaded. When running a reflow cycle, these settings will now be used.

Editing the active profile

Navigate to Edit profile and press OK, then navigate to the parameter you wish to edit. The options are Ramp up rate, Soak temperature, Soak duration, Peak temperature, Peak duration and Ramp down rate. Press OK once you have selected the option to edit, the controller will display the value and allow editing using the < and > keys. Press OK to confirm your changes, or to cancel press Back. Repeat these steps to edit each parameter you wish to adjust.

When running a reflow cycle, the controller will use the settings as per your adjustment.

N.B. This process edits the variables stored in RAM and does not save the changes permanently until you save the profile.
Fan Idle Speed Adjustment Procedure

The oven's cooling fan is used to provide a small amount of air movement inside the oven, this helps the oven evenly heat the PCBs. The speed of the fan is important, too fast and the oven is being actively cooled while trying to heat up, too slow and the PCB will be heated unevenly.

The fan is run at a fixed 'idle speed' during reflow to provide a small amount of air movement in the oven. The fan should idle very slowly, to adjust the idle speed:

  • Navigate to Fan settings in the menu.
  • Press OK, Idle Speed will display on the screen.
  • Press OK to edit. (The default value for the fan idle speed in T962A is 35, for the T962 the default is 15.)
  • Test this idle speed by starting a reflow cycle, the fan should start up easily but not run so fast as to cause the oven to be cooled dramatically during reflow.
  • It is very important this value is set high enough for the fan to start every time the cycle is started (at low values, the fan will not be able to start spinning) but it is equally important not to set this speed too high, otherwise the fan forces too much cool air into the oven and reduces the efficiency of reflow soldering.

If the PCB temperature profile does not follow the programmed profile settings closely:

  • Set the Fan idle speed to a low value and ensure that the fan starts when a reflow cycle is started.
  • Perform a test profile using a PCB with thermocouple and observe the resulting temperature profile of the PCB.
  • Increase the Fan idle speed by 5-10 and repeat the test cycle without changing any profile settings.
  • When the PCB temperature accurately tracks the programmed profile temperature, note the Fan idle speed value and ensure it is saved.
Profile tuning tips

To get the best from your reflow oven, it is advisable to perform a series of tests to determine the settings required to properly reflow each design of board you work with. Boards of different masses will behave differently and may require different soak duration, temperatures etc. to properly reflow all solder joints on the board.

Refer to the data sheets for all the parts you use to determine the allowable reflow profile for the design. Once the peak temperature of the most sensitive part is known, this must not be exceeded anywhere on the board.

The board's temperature lags behind the heat of the heater tubes, the oven controller is not controlling the board temperature directly, but the air temperature inside the oven via the thermocouple mounted above the PCB. However, the surface of the PCB will absorb more energy than the thermocouple directly due to the IR radiation, meaning that it is possible for the PCB temperature to overshoot the air temperature in the oven.

The PCB temperature should always remain below or equal to the profile temperature set using the controller; until cooling begins. If the soak duration is too long or the ramp rate too slow, the board temperature will exceed the soak temperature before the soak stage of the profile is completed. This will cause the temperature of the board to remain above the profile temperature that has been set, resulting in the peak temperature being higher than required.

There is an offset between the air temperature and the board temperature. Often, the peak board temperature is higher than the air temperature measured immediately above the boards. Be aware of this when choosing profile settings as a peak temperature of 220°C can result in a peak board surface temperature of 240-250°C. If the fan speed is set too slow, this offset can be even larger. Performing testing (see Reflow Profile Testing) will allow you to determine the best settings for a given board.

Towards the end of the peak stage of the reflow cycle, the board will reach its own peak temperature. During cooling, the air temperature needs to drop quickly below the melting point of the solder and continue to decrease to adequately cool the board.

Ideal Fan idle speed Adjustment

If the PCB temperature does not closely follow the profile temperature settings, consider carrying out Fan Idle Speed Adjustment procedure.

To work out the best profile settings adjust the following, one at a time, in small increments, in this order:

  • Soak time
  • Soak temperature
  • Peak temperature
  • Ramp up rate (as a last resort for heavy boards)

Repeat the test cycle to confirm the effect of the adjustment. If the PCB temperature overshoots the soak or peak temperature by more than 2°C, abort the reflow cycle and reduce the soak or peak duration appropriately. When the reflow cycle is aborted the oven will immediately begin cooling, wait for it to reach ambient temperature before beginning another test cycle.

Any of these changes alone can be enough to alter the profile to be suitable for your needs, take small steps to avoid large unexpected changes. A small change to the soak duration can have a large effect! The board temperature profile should not completely level off or begin to drop during soak, it should continue to climb slowly toward the desired soak temperature. If the board temperature exceeds the soak temperature before the end of the soak stage, reduce soak duration.

When viewing and adjusting reflow profiles, there are a few crucial points during the cycle to examine:

  • When transitioning from soak to ramping up to the peak temperature, the PCB temperature should have almost equalised with the oven temperature. If the PCB temperature is rising past the programmed soak temperature, the soak duration is too long. If this occurs, the PCB temperature will likely be too high for the remainder of the cycle.
  • At the start of the peak stage of the reflow cycle, the oven and board temperature should be a few degrees below the desired peak temperature, if the board temperature is overshooting the desired peak temperature, either increase the fan idle speed slightly or reduce the soak duration.
  • When cooling down, the air temperature of the oven needs to drop a lot faster than the desired board cooling temperature to ensure the desired board ramp down rate is met. It takes several seconds for the air temperature in the oven to begin to reduce at the start of the cooling phase. Ensure that the duration of the Time Above Liquidous is appropriate for your solder paste and parts.
Care and Maintenance

ESTechnical recommend the following care and maintenance should be carried out at the intervals specified in order to get the best performance and longest useful life-span from your reflow oven.

Before every use
  • Check that the oven has adequate air flow around it and that no grilles are covered.
  • Ensure the drawer is clean and free from dirt, dust or other potential contaminants.
  • Start a reflow cycle with no PCB(s) in the drawer, confirm that the main cooling fan starts to idle gently, abort the reflow cycle.
After every 50-100 reflow cycles
  • Remove the drawer from the oven, clean the drawer and internal surfaces of the oven being careful not to damage the oven thermocouple or heaters. Flux deposits will harm the performance of the reflow oven, remove these with flux thinners or a dedicated reflow oven cleaner such as Electrolube ROC.

Packing list

  • 1x ESTechnical Desktop Reflow Oven T962A
  • 1x USB A to B cable
  • 1x K-Type thermocouple with miniature connector
  • 1x 10mm kapton tape
  • 1x 1g syringe heatsink paste
  • 1x Power cable
  • 1x Operation manual

EC Declaration of Conformity

In accordance with EN ISO 17050-1:2004

We, ESTechnical

of

12 Ormonde Road,
Folkestone,
Kent,
CT20 1PG,
United Kingdom

in accordance with the following Directive(s):

2004/108/EEC The Electromagnetic Compatibility Directive
2011/65/EU ROHS 2

hereby declare that:

Equipment:
ESTechnical Reflow Oven T962A

the equipment named above complies with all applicable Essential Requirements of the Directives.

Signed by: Ed Simmons

Position: Founder

Carried out at:
ESTechnical
12 Ormonde Road,
Folkestone,
Kent,
CT20 1PG,
United Kingdom

on
16th September 2013

reflowoven.txt · Last modified: 2017/05/25 16:15 (external edit)