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Mini Reflow Plate

For Assembling or Repairing Small SMD Circuits

The transition to SMD miniaturized components marked, for many, the beginning of a series of assembly difficulties to be overcome. In addition to the not-so-easy placement of components, specific temperatures and timing must be adhered to for the soldering cycle. Professional reflow soldering stations are expensive. In this article, we present an effective yet reasonably priced solution for assembling/repairing our boards.

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What is Elektor Exclusive?

Materials

Gerber Mini Reflow Plate.zip

SW Mini Reflow Plate.zip

Component list

Component List

Resistors

R1…R3 = 470 Ω
R2 = 10 kΩ
R4…R5 = 47 kΩ

Modules

U1 = Arduino Nano

PS1 = 3WMA2205V (PSU Module)

BRD1 = MODMAX6675 (for K-type thermocouples)

LCD1 = OLEDGVSCSD (0.96″ OLED)

Miscellaneous
BZ1 = 5 V buzzer (without oscillator)
Header strip, female, 4 pins
Header strip, female, 15 pins
Header strip, female, 5 pins
Screw terminal block, 2 poles

Rotary encoder with pushbutton

Heating element: 400WPTCRISC on https://futuranet.it
also available from Aliexpress and Ebay by searching for "400W PTC heating plate" (choose 400 W version, and the correct voltage for your country)

Discussion (0 comments)

white rabbit 1 year ago

I read this article with great interest, since I am contemplating building something like this myself. I am somewhat dismayed that the specifications of the heating plate are missing.

What size is it?
How many watts is it rated for?
What is the maximum temperature it can reach?
Is it resistive or PTC?
What is the manufacturer part number or other identification?
What is the procurement source?

Addition of this information will complete an otherwise excellent and useful construction article.

0 Comment(s)

Phillip Norman 1 year ago

This article is incomplete in the English magazine! If you download the article from the link above you will see the Italian version (!!). However, the heating plate is identified as a 400w PTC device - readily available. The pdf also provides a link to the firmware ... but it re-directs to a general project page. I would very much like to have a go at building this, but don't have the time at the moment to second guess what the firmware is doing ...

0 Comment(s)

J.F. Simon, Elektor 1 year ago

Hello, we have updated the article, now you can download the software and the Gerber files for the PCB. Unfortunately we don't have the design files for the enclosure. We also added info about the heating plate in the parts list. Best regards, JFS

Phillip Norman 1 year ago

Many thanks for the speedy update. Parts ordered - looking forward to having a play with this!

1 Comment(s)

Southerner 1 year ago

Phillip the firmware download still does not work. clicking on that zip file opens a new tab but goes to this very same page and not the firmware or zip file. I had planned to build the reflow plate but can not do it without the firmware hex file or INO file.

Thank you.

J.F. Simon, Elektor 1 year ago

Hello! I can confirm that clicking on the "SW Mini Reflow Plate.zip" link works and starts downloading the file. Maybe this could be a browser issue on your side? You may also check your "Downloads" folder. Alternatively, you will find the same file attached to this message. Best regards, JFS

230456-027-05-ORIGINAL-SW Mini Reflow Plate.zip (22kb)

1 Comment(s)

Southerner 1 year ago

Is the gerber file correct? I have tried to upload it to 3 different board houses and all say the file is invalid and has zero layers.

J.F. Simon, Elektor 1 year ago

Hello, the ZIP file you downloaded contains the PCB files both in Gerber and PDF formats. You need to open it first, inside there is a "Gerber" subfolder, containing a gerber.zip file. The gerber.zip file is accepted by both JLCPCB and PCBWay, and probably others too which I didn't try.

Southerner 1 year ago

Thank you for the information. I did figure that out and was surprised that I had to unzip the zip file to get the gerber zip file but the boards arrived today.

Thank you.

1 Comment(s)

Southerner 1 year ago

Is the enclosure available? If not, are the STL files available to make and enclosure for the Min Reflow Plate?

J.F. Simon, Elektor 1 year ago

Hello,
Unfortunately, the STL files were not provided to us, I'm sorry for the inconvenience. We don't sell the enclosure either. I would recommend that you use a plastic electrical enclosure (which can be bought in many hardware / home improvement stores), big enough to also contain the external SSR required to drive the heating element. That way, the overall wiring can be neater (one mains cable input, two wires for the output to the heating element)

1 Comment(s)

Guy Melon 1 year ago

Hi,
How did you fixed / mounted the thermocouple on the heating element ?

J.F. Simon, Elektor 1 year ago

Hi,
the author suggests inserting the end of the thermocouple in a ring terminal and crimping "without exaggeration" (it may be hard to get it just right) and using a screw to bolt it to the plate. However, the only holes in the heating plate are near the edges; not the ideal spot to check the temperature. It may be possible to drill and tap a tiny hole in the middle of the heating plate, but I would advise against it as there is a high risk of drilling into the resistive wire inside; thus risking both damage to the plate and exposure to electric shock. The second option mentioned by the author (sticking the thermocouple to the PCB with kapton tape) is better and gives a more accurate temperature reading, provided that you stick it well enough. A third and, IMHO even better solution is to use a small piece of scrap PCB that you cut from an old board (at least 2 layers and with a some ground planes, to be representative of modern electronics), choose a thermocouple that's thin enough, and place it in a small hole in that scrap PCB, with a dab of thermal paste. And then you place this “dummy PCB-probe” right next to the PCB you are soldering. Then you get a good estimate of the temperature of your “real” PCB, and you don’t need to mess with sticky tape.

1 Comment(s)

Southerner 1 year ago

I noted that in my printed copy of this article it shows R1 as being 470 ohms on the schematic but 10K in the parts list but this thread shows it as 470 ohms. Which value should be used for R1? 470? or 10K

Thank you.

J.F. Simon, Elektor 1 year ago

Hello, sorry for the discrepancy, we do our best to avoid this type of error and reread several times, but unfortunately typos like this still happen sometimes. The problem is not with R1, R1 is 470 Ω in both the schematic and the parts list. (By the way, this resistor can be optional, depending on the SSR you are using: many SSR have already a built-in resistor to limit the current in their internal LED that is on the control side. But, better safe than sorry, that's why the author recommends a resistor anyway). The problem is with R2. As it is a pulldown resistor, 10 kΩ is a better value than 470 Ω. It turns out that in this particular application, as the signal that's pulled down comes directly from the rotary encoder and the 5 V power supply (that is, very low impedance), both values would equally work; but still, 10k is a more reasonable value.

Southerner 1 year ago

Mr. Simon you are correct. It was R2 I was asking about but "fat fingered" the typing. I have no issue with errors creeping in and that is why I like these forums so that errors can be caught and the correct information available.

One thing I would like to see in articles like this are suggestions for enclosures or information about what the author used (if any). Enclosures are often more a problem than the circuit itself.

Thank you.

1 Comment(s)

astroboy 1 year ago

1.- About the rotary encoder in this article, the part list doesn't includes the part number (model and manufacturer). Could you indicate this information for the encoder, please? This will complete my order list.

2.- Resistor R1 is connected to PIN 3 of the Fotek SSR-25-DA relay...right?

J.F. Simon, Elektor 1 year ago

Hello,

1- there are many many part numbers of encoders that could work for that, depending on what you want in terms of shaft length, shaft type, and what's in stock in your favorite parts supplier. (I suspect many generic ones from Ebay/Ali could fit too). You can use the Gerber files (or the snippet attached to this comment) as a reference. I think, for example, Farnell 2663532 should fit.

2. yes, correct. Good luck !

encoder.png (55kb)

astroboy 1 year ago

Hi Simon,

Thank you very much for your answer, your comments and the image will be very useful for me...

I will start the mini reflow plate the next days...If there is some relevant observation, I will let you know

Best regards