TEMPERATURE CONTROLLER FOR A SELF …spectecs.com/UserGuide_ReflowController.pdf · Temperature...

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Temperature controller for a self-assembled reflow-soldering station Issue 17/21-09-2017

domestic mini oven; all are availableat relatively low cost.

The SpecTecs is the ideal

choice of controller for such a system.Advice on the other componentsneeded is given later in the document.

Temperature controllerDescriptionThe EasyReflow temperaturecontroller and interface software havebeen developed especially for self-assembled reflow soldering stations.The firmware design is a veryconvenient to use form comprising aUSB dongle and PC interfacesoftware. The user only has toprovide the cables, ( and pc ! ).

The dongle connects to a pc via usb,and to the reflow-soldering system viathe 4 position screw terminalconnector. The dongle is usbpowered.

The software has a clearly laid out,user friendly interface. The user hascomplete control over configuring thetemperature profile to be used. Justenter ‘settings’, select leaded orunleaded solder, choose temperaturethresholds and duty cycle*. Thenstart the process. Pop-up text tips areavailable for most functions.

TEMPERATURE CONTROLLER FOR A SELF-ASSEMBLED

REFLOW-SOLDERING STATION

IntroductionReflow-soldering is the process ofsoldering a printed circuit boardpopulated with, typically nowadays,surface mount components in a heatedoven in one operation.

The rate of heating and cooling iscontrolled and follows a predeterminedprofile to minimise the thermal stresson the components. This temperatureprofile comprises several phases viz,ramp to soak (R2S), soak, ramp toreflow (R2R) or peak, reflow (liquidius),and cooling.

Commercial, proprietary, industrialreflow soldering stations may be toocostly for the low volume producer,electronics enthusiast and experiencedhobbyist. A viable alternative is a selfassembled system, built cheaply,capable of excellent results, andrepeatable quality.

Such a system comprises thetemperature controller, thermocouple,solid state relay, ( SSR ), and a

n USB dongle style

n USB powered

n Type-K thermocouplecompatible

n Incorporates MAX6675thermocouple to digitalconverter

n Range 0 C - 250 C

n Accuracy <~+2.5 C

n Resolution 0.25 C

n Measurement interval 1sec

n Data transfer rate 16 bits/sec

n Status LEDs

n Non volatile memory

n Interface software

n Serial numbered

n Size 90 x 22 x 15 mm



Also full status is reported in the status bar along thelower edge of the ‘process control’ window.

InstallationInstalling the Dongle

Connect screw-terminal positions 1 - 4 as follows. Notethat the blue dot is adjacent to position 1.

1. Thermocouple –

2 Thermocouple +

3. SSR input +

4. SSR input --

Connect a short, thin, wire jumper between 1 and 4.

The coloured status indicators on the dongle itselfindicate the following conditions:

Power

Red = Vbus. ( Normal )

Dark = no Vbus.

USB **

Green = Usb configuring.

Dark = Usb configured.

Data transfer

Yellow = no transfer.

Dark = transfer in progress.

Duty cycle *

Blue = ON period ( +DUT).

Dark = OFF period ( – DUT ).

Plug the dongle into a usb socket; a usb cable may berequired. It should be ready for use after the usb statusindicator is in the off state which should take only afew moments. If not, reinsert the dongle.

Connecting the Thermocouple to the Dongle

Examine the plug on a type-K thermocouple to identifythe ‘+’ and ‘-’ wires. Remove the plug. Connect ‘-’wire to screw terminal position 1 and ‘+’ wire toposition 2. If it becomes necessary to recheck which isa particular wire, connect a millivoltmeter across both

free ends while holding the other end between thefingers; a positive voltage will be measured if the wiresare connected to the millivoltmeter with the correctpolarity.

Connecting the SSR to the Dongle

Identify the input ‘+’ and ‘-’ low dc voltageconnections on the SSR. Connect ‘+’ to screw terminalposition 3 and ‘-’ to position 4.

Installing “ReflowControl” Dongle interface software

The software has been tested with Microsoft WindowsXP(Pro SP3), Vista(Home), 7(Ultimate SP1), 8.1, 10.

( XP users should check first by installing and trying torun the software before purchasing the dongle. Refer tonote

If the software has been supplied on disc it shouldinstall automatically after inserting the disc; otherwisebrowse the storage media to where the installation filehas been saved and run ‘setup.exe’ manually. Thesoftware can be uninstalled using ‘Add or RemovePrograms’ or ‘Programs and Features’ or uninstall fromthe start menu - programs.

The self-assembled reflow-soldering stationMini oven

Typical domestic mini oven - “toaster oven”

Domestic mini oven, recommended power >1800Wdepending on its volume.

The mini-oven should be capable of reaching atemperature of at least 220C in less than 4 minutes.



The temperature should always be set to maximum. Ifthe temperature does not reach the peak before thethermostat operates, it will need to be bypassed. Duringsoldering the temperature will be controlled by thedongle. Consideration could also be given to insulatingthe space between the oven cavity and case withmineral wool.

Thermocouple

A thermocouple is required. The voltage totemperature conversionperformed in the software isonly accurate for this typeof thermocouple. Thethermocouple wire mayenter the oven from around

the door. A better method is to make a small hole in therear of the oven, through which a metal tube is passedand fixed in position. Then the thermocouple is passedthrough the tube to the centre of the oven cavity. It willthen remain in that position between soldering sessions.Remove the plug and connect both wires to the dongle.

Solid state relay, SSR

The SSR switches on/off the power to the ovenaccording to the duty cycle.In this way the temperature iscontrolled.

AC current rating at least10A, preferably 15A.

Capable of 5Vdc, <25mAoperation.

Connect the output terminals,using any crimp connectors

provided, in series with the ac mains lead live connectionto the mini-oven.

The connections made to the SSR will beconcealed under its clip-on protective cover. The low dcvoltage input terminals are connected to the dongle.

Using the Dongle and SoftwareThe Dongle must be available and plugged in beforerunning the software. All parts of the reflow-solderingstation should be connected together; the ovenplugged in to a power outlet, and switched on byadvancing the timer >8mins. Temperature set to themaximum. Oven door closed.

Calibrating

Before soldering a populated circuit board, the ovenshould be “characterised” by using the software toestablish the duty cycle to use for each phase of thesoldering process, according to the particular type ofsolder selected.## The software has preset templates,default temperature thresholds and duty cycles* to useas a starting point.

Start the “ReflowControl” application. The ‘processcontrol’ window is displayed.

The ‘process control’ window has two main areas;settings for leaded solder and settings for lead-freesolder.## Initial preset default temperatures and dutycycles are displayed. Note that the temperature insidethe oven is already being measured and displayed everysecond.

Click on the ‘View - Templates’ menu bar item or‘templates’ tool bar icon to open the ‘templateswindow’. The ‘templates’ window shows three presettemperature profiles.## However, new custom usertemplates, ( up to 5 ), can be entered and saved tomemory with the ‘New’ button.

Click on the ‘Memory - Display’ menu item or ‘memorydisplay’ tool bar icon to display memory contents.

Decide which profile, Pb or No-Pb, to base thecalibration of the oven on.

Select settings, and choose solder type. Use the presettemperature thresholds and duty cycle defaults fornow. Click ‘Go’ to start the process. The temperatureinside the oven is plotted in real time in the ‘templates’window. Stop and restart the process as often asnecessary to make adjustments to the duty cycles*, sothat eventually the measured heating profile is the bestfit that can be obtained to the chosen template.



Increasing the duty cycle increases the rate oftemperature change, decreasing the duty cycledecreases the rate of temperature change. Thetemperature should stay within the soak band duringthe 2 minute soaking phase, and ideally be constant, toachieve thermal equilibrium of the board andcomponents before the R2R phase.

As a test, place a tiny amount of solder paste on thecopper side of a scrap piece of pcb laminate material, ofan approximate size to that which will be typically used.Place it centrally inside the oven and restart the reflow-soldering process using the calibration values. When theprocess has completed after about 8 minutes, allow theoven to continue to cool. The temperature is still beingmeasured. When cool enough to handle, remove andinspect the test board for signs of overheating,discolouration, lifted copper foil etc. The solder pasteshould have completely melted into a shiny metallicpatch.

If all is satisfactory, the calibration is complete.

Retain the original defaults, note the current settings orsave the current settings as the new defaults. Repeatfor other solder types if they will be used.

The reflow-soldering station is now ready for solderingpopulated boards, with repeatable quality.

The screw terms can be unplugged

Product label green or white back-colourAlternative style grey ABS enclosure



Process Control window ( rev22 )



Templates window ( rev22 ) - measured Pb profile

Alternative style clear ( translucent ) ABS enclosure



Templates window ( rev22 ) - measured NoPb profile



Templates window ( rev22 ) - custom user template added

The storage in flash eeprom of each memory address used for the custom template is 1 byte wide. When creating a customtemplate the time and temperature values for each point on the template except the ‘end of process’ point must be enteredas integer values <256 seconds and <256 degC. Values corresponding to the ‘end of process’ point are ignored, notsaved and discarded when the template is loaded. For this reason, it will be noticed that the template is truncated at the‘start of cooling’ point. This limitation is due to hardware and not the software. The rate of cooling, however, after theoven door is opened is not so critical.

When loading a custom template into the templates window from memory using the ‘Load’ button, the memory windowmust always be opened first, using the menu bar ‘memory’ item, or the tool bar ‘memory’ icon.

When creating and saving a custom template using the templates window, the memory window does not need to bedisplayed. It can be displayed afterwards to inspect the refreshed contents.



Memory window ( rev22 ) - memory contents showing a custom 1 template has been saved on row 3



OvenTempCheck software

The following are brief notes on the oven temperature checker ‘OvenTempCheck’ software.

The “EasyReflow” temperature controller dongle and “ software are ideal for checking thesuitability of a mini-oven for reflow-soldering applications. If a used secondhand mini-oven is being considered itmight be possible to check how quickly the oven reaches the peak reflow temperature. In fact any domestic,household oven ( not microwave ) can be checked for temperature accuracy ( upto 250degC ) compared with thetemperature set. Duty cycle control is not required for this application; so no duty-cycle functionality is provided bythe software.

Features, functions and use.

Instal and read “ ”. Connect the dongle and run “ .

● Optional oven details can be entered, e.g., make, type, model. s/n, owner etc.

● Measurement process duration is 20mins, but process can be paused/stopped at any time.

● Thresholds as plotted lines can be set using the ‘Test Temp’ buttons, for ease of reading the graph.

● ‘Open new data file’ - “ ” must be opened from the application installation directory to load into thedata measurement table before starting the measurement process.

● ‘Start’ - real time data is plotted and tabulated in the measurement data table every second.

● The real time data is date/time stamped.

● ‘Save to data file’ - after the measurement process has completed, measurement data can be saved to an xmlfile. Do not overwrite “ ”. If “ ” is accidentally overwritten, OvenTempCheck will need to bereinstalled.

● ‘Open data file’ - loads archived data from an xml file into the data measurement table.

● ‘Plot imported data ‘- plots the archived data.

● ‘Remove row’ - removes selected row from the data measurement table.

● ‘Clear all’ - deletes all rows except the first from the data measurement table. If the table is populated, use‘clear all’ before importing new data.


OvenTempCheckv1.0.0.rev1



Feedback is welcome to [email protected]

SpecTecs accepts no responsibility for any damage caused to the usb temperature controller dongle by any apparatusconnected to it, nor caused to such connected apparatus, nor for any errors or omissions in this document. Any useby the purchaser of the dongle and/or software implies acceptance. The owner/user of the reflow-soldering station isresponsible for own personal safety in assembling and using the reflow-soldering station.

The specification, features, functions and appearance of this product may change without notice as required by anyfuture product development and improvement. ( see ).

* The software provides a range of duty cycles in 5% steps. If required, other integer value(s) within the range canbe included on request.

** Enumerates as a Human Interface Device, HID. Generic HID driver used. No additional drivers are required, ( builtin support on Windows® XP, Vista, 7, 8 and 10 ).

# Microsoft .NET Framework v4 or higher is required. If necessary visit https://www.microsoft.com to download.There may, or may not, be an initial problem running ‘ ‘ under Windows® XP. If some Windows®system files are missing from the host system which are dependencies of a dll file installed by the applicationsetup.exe a runtime error message is displayed. The application should be closed and [email protected] contactedfor the solution to this issue.

## The software does not support low temperature solder directly. However, a low temperature template is displayedin the ‘template’ window for user experiments to calibrate the reflow oven for low temperature solder, by makingchanges to either the Pb or NoPb solder settings in the process control window.

( Microsoft Windows® XP, Vista, 7, 8, 10 and .NET Framework are all registered trademarks of the Microsoft Corporation )/

“ Enjoy using the EasyReflow Temperature Controller Dongle “- the SpecTecs EasyReflow team

Internal view

http://www.saprojectsonline.com/contact.html

http://www.saprojectsonline.com/contact.html



AnnexChange Log

ReflowControlv1.0.0.rev 21

1. Preset template for low temperature solder added in ‘Templates’ window.

2. Up to 5 user custom templates can be created, saved and loaded into the ‘Templates’ window.

3. Addresses hex 30 to 6F added to memory view in ‘Memory’ window.

4. Minor cosmetic, style changes and additions to ‘Templates’ and ‘Memory’ windows.


1. Process Control window : title bar text changed, “Profile” replaced with “Solder”, NoPb temperature thresholdsright aligned, “End Reflow” replaced with “Peak Reflow”.

2. About window : text added.

3. Templates Window : size of soak bands reduced, low temp soak band added, order and colour of graph serieschanged, real time data series changed from “actual” to “measured”.


1. Process control : in window title bar text changed and changed tab key order, improved procedure for handling Pbduty cycles.

2. Templates window : ‘low temp - template’ renamed ‘low MP - template’ for low melting point solder, ‘low tempsoak band’ renamed ‘low MP soak band’ for low melting point solder.


1. Process control window : window now opens without the dongle.

2. Changed Retry/Cancel dialogue text in message box if dongle not found.

3. Process control window : changed Exit controls tool-tip texts.

4. Process control window : changed order of controls on Tool Strip.


1. Process control window : title bar text changed.

2. About box : text changed.

3. Splash screen : copyright notice changed.

TEMPERATURE CONTROLLER FOR A SELF …spectecs.com/UserGuide_ReflowController.pdf · Temperature...

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