**Building a DIY Hot Plate Reflow Soldering System**
After months of anticipation, I finally received the PCBs and components for my DIY hot plate reflow soldering system, courtesy of Chris's meticulous design and instructions. As per the plan, we needed an Atmega328p microcontroller as the brain of the operation, two push buttons to control the user interface on an OLED display, and a MOSFET output to quickly adjust the heating power.
To top it all off, we also required complementary power regulators and protection components to ensure safe and reliable operation. The theory was clear: this hot plate control circuit needed to be able to follow the reflow soldering curve while implementing various safety features. Chris had written the code in a way that made sense to me, even though I wouldn't delve into its details.
With the theory out of the way, I downloaded the Gerber files and component list from GitHub to order the PCBs from JLCPCB and procure all the necessary components. After a week, everything arrived at my doorstep, and it was time for assembly. However, one critical component – the microcontroller Atmega328p – was nowhere to be found. I had to get creative and borrow an Arduino Uno's microcontroller instead.
Next, I carefully spread solder paste onto the PCB and positioned all the components in their designated spots. Using my hot air station, I successfully soldered the SMD components, followed by a thorough cleaning with isopropanol to ensure everything was properly attached. Under the microscope, the result looked promising.
Afterwards, I soldered the THT components into place and performed a first test run using 12V power without any issues. With the microcontroller in hand (or rather, borrowed), I programmed an Arduino Uno as an ISP programmer to connect it to the hot plate's microcontroller via the ICSP interface.
To set the correct fuses on the microcontroller, I chose the right programming settings and attempted to burn the bootloader using the external crystal. Unfortunately, this didn't work out as planned, but I had a function generator lying around to inject the clock signal into the microcontroller.
With that done, I was finally able to upload the bootloader and main code for my DIY hot plate reflow soldering system. Adding the OLED screen and powering everything up, it seemed like everything worked correctly, with a simple user interface allowing me to choose a temperature.
I then added metal standoffs and performed a first heat-up test, which drew quite a bit of power but successfully heated the surface without any issues – albeit with a slight 15C difference from the real temperature. This wasn't a concern for my reflow soldering tasks, which I proceeded to try next, resulting in pretty much all of them turning out great.
I must admit that working with an aluminum PCB presented some space problems, but it ultimately worked out somehow. Overall, I'm thrilled with this DIY hot plate reflow soldering system and excited about the prospect of using hot plate reflow soldering as my new favorite soldering technique – easy to do and highly effective.
Both the DIY and Buy versions have their advantages and disadvantages, with the PCB version's biggest concern being its uncertain lifespan due to repeated heat-up and cool-down cycles. However, the DIY version is significantly cheaper if we calculate the cost of building one PCB, which might become a viable product in the future.
With that said, I believe both the DIY and Buy versions are winners for me this time around. If you've enjoyed learning about this project with me, don't forget to like, share, subscribe, and hit the notification bell to stay updated on my next adventures! Stay creative and see you next time.
WEBVTTKind: captionsLanguage: enRecently I ran into a soldering problem afterreceiving 3 new printed circuits board designsI made.You see the first ones challenge is that itis an aluminium PCB and the second and thirdones challenge is that they need plastic connectorssoldered to them which come with tons of veryclose to one another pins.And my soldering problem for these PCBs isthat I am simply not satisfied with the solderingtechniques I am familiar with so far.Hand soldering does not work for the LEDssince they cover the spot where I have tosolder them and due to accuracy reasons itis also very hard to hand solder the connectorsin place.Spreading solder paste and using hot air toreflow solder the connectors is possible butwith this technique I often like to burn thingsand sometimes even fry components and additionallyit does not really work for the LEDs sincethe aluminium gobbles up all the heat.And last but not least I got the reflow ovenwhich does work in both cases but you canhardly see what is going on on the PCB andthis solution is also bulky.And that is why I was looking for anotherbetter technique and quickly found out abouthot plate reflow soldering which like thename implies is basically a hot plate thatheats up and thus evenly heats up the PCBon top of it as well.So I bought myself such a hot plate and whiletesting it out; a viewer of mine reached outto me with a DIY solution which I of coursealso had to try out.That means in this episode of DIY or Buy wewill not only find out whether hot plate solderingis the best soldering technique for me butalso whether you should make your own hotplate or simply buy one.Let's get started!This video is sponsored by JLCPCB, who offerthe most affordable PCBs, SMT assembly serviceand also 3D printing service.Every PCB I ordered so far arrived at my placewithin a week and needless to say the qualityis excellent.So why not start your PCB and SMT adventuretoday at a price point of only $2.And if that is too much for you then let metell you that the top 8 comments underneaththis video with the most likes will get a$50 JLCPCB discount code.Let's start off with the commercial solutionand I think I got the most popular one withthe MHP30 Hot plate that you can get for around$100.For that price you get an excellent and robustbuild quality combined with a USB Type C PDinput and an intuitive to use user interfacethat you control with 2 push buttons.That all sounds nice but can this hot platedo its main job properly?To find that out I prepared a small PCB withsolder paste and placed the components onit.Now the solder paste I am using is the SN42Bi58type which according to the internet comeswith a low melting point but according tosome reflow curves I found the peak temperatureshould be around 160 degree Celsius.And by the way the buy hot plate apparentlydoes not follow such a reflow curve and onlyheats up and stays there but the DIY solutionlater does feature a temperature curve.But honestly speaking I only care about agood soldering end result.And with that being said I set the temperatureof the commercial plate to 160C and firstlygave it a test run.As you can see the plate heats up withouta problem and the displayed temperature isalso close to what the real temperature is.That means it was time for a proper test andI have to say that also worked out flawlesslyand I was very happy with the end result.So all in all the buy option is a functionalhigh quality hot plate which basically onlycomes with one major flaw and that is itssmall size which makes it hard to use formedium sized boards.Now of course there are big and bulky hotplates you can buy as well but it feels likethere is nothing in between.But here comes the DIY option into play whichwas presented to me by a viewer named Chriswith pictures likes these and I was immediatelyinterested.You see the concept of his design is thatwhen you have a long enough copper conductorit comes with a non neglectable resistanceand when current flows through that it createsheat.Instead of using copper wire though, Chrisdesigned a long copper trace on a PCB whichin this case comes with a resistance of 1.2ohm.And once again by letting current flow throughit, it can reach very high temperatures forreflow soldering.But we also need control electronics in orderto not let the temperature rise indefinitely.Chris of course came up with its own systemwhich I want to explain briefly.The heart of it is like usual a microcontroller,in this case the Atmega328P which is the heartof many Arduinos.The microcontroller of course needs a coupleof important inputs and outputs for such ahot plate job like a temperate sensor in orderto know how hot the plate is.In this case we are using the LMT85 that outputsa voltage almost linear to the measured temperature.Then we need two push buttons as inputs inorder to control the user interface shownon an OLED that acts as an output.And last but not least most importantly weneed a MOSFET output that we can turn on andoff quickly in order to adjust the heatingpower of the hot plate.Of course we also need some complementarypower regulators and protection componentsbut overall this is all such a hot plate controlcircuit requires.And all that is now missing is a bit of codethat lets all components interact with oneanother in order to ultimately let the hotplate follow the reflow soldering curve whileimplementing some safety features.Now I will not go into detail about the CodeChris wrote but let me tell you that it iswritten in a way that you can easily understandeverything.If you are interested in getting it or buildingthis project then you can have a look at itsGitHub page.But anyway with the theory out of the wayI downloaded the Gerber files and componentlist from GitHub to not only order the PCBsfrom JLCPCB but also get all the components.After a week all the stuff arrived at my placeand at this point it would have been timefor the assembly, but sadly one importantcomponent was still missing.The problem is that ordering the microcontrollerAtmega328p is pretty much impossible or wayto expensive nowadays but what is not impossibleis buying cheap Arduinos.So I had to steal the microcontroller fromone and then it was time to spread the solderpaste onto the PCB and position all the componentson there.The way I like to do it is to go through eachcomponent bag individually and then crossingoff the components I just placed on the schematic.This way I know for sure what components arealready on the board and what is missing.But anyway after all SMD components were inplace, I used my hot air station to solderthem and then cleaned the PCB with isopropanolbefore having a look at it under the microscope.The result didn't look half bad but I touchedup the microcontroller once more just to beon the safe side.Afterwards I soldered all the THT componentsin place and did a first test run with 12Vpower which didn't let it explode, brilliant.So next I programmed an Arduino Uno to bean ISP programmer which I then connected tothe hot plate microcontroller through theICSP interface.And if all of that sounds super complicatedto you then simply have a look at the howto program guide from Chris where it is allexplained with more details.So after choosing the correct programmingsettings I wanted to set the correct fusesof the hot plates microcontroller by burningthe bootloader which sadly didn't work atall.Guess what?Since the microcontroller was used with anArduino that uses an external crystal forthe 16MHz clock signal, it will not functionin any way without receiving such a signal.But since I knew where to inject the clocksignal and had a function generator lyingaround, it was no problem to do just that.And thus it was finally possible to not onlyupload the bootloader but also the main codeof the DIY hot plate.And after then adding the OLED screen andpowering everything up, it seems like it allfunctions properly and I like that the userinterface is very simplistic by only lettingyou choose a temperature.So next I added metal standoffs and went fora first heat up test, which drew quite a bitof power and heated the surface up withouta problem but featured a slight 15C differenceto the real temperature of the hotplate.But you know that shouldn't be such a bigdeal for my reflow soldering tasks which Itried out next and I have to say that prettymuch all of them turned out great.Of course when it comes to my aluminium PCBthen there are still space problems but itdid work out in the end somehow as well.So all in all I can now say that hot platereflow soldering is my new favorite solderingtechnique because it is so easy to do.And I am also very happy with the DIY versionas well as with the Buy version which bothcome with their own advantages and slightdisadvantages.The big one of the PCB version is that itis not clear how often the PCB can handlethis heat up cool down process meaning itwill probably not survive as long as the buyversion.But then again DIY is a lot cheaper if weonly calculate with the price to build onePCB which you will hopefully be able to enjoywhen Chris turns this all into a proper product.And with that being said I think both DIYand Buy are this time the winner for me andI hope you enjoyed this project and learnedsomething along the way.If so don't forget to like, share, subscribeand hit the notification bell.Stay creative and I will see you next time.
