Making PCB Hot-Plate v2

[Music] welcome to the pcb cooking show where today i'm going to show you how i made this new pcb hot plate if you remember a few months ago i made this prototype which talks less given all the problems that i've had so let me show you how i try to fix them i started with the track resistance last time i messed this up because i based my target resistance based on thermal properties of flexible pcbs so my goal was to achieve 25 ohms which i also simulated incorrectly because the actual resistance was measured to be 38 ohms after the video i found that the error in my simulation was including the plating thickness to power the hot plate with like 12 volts the target resistance should be much lower in fact i verified this with some research and i found that 3d printed heat vests usually have a resistance that is less than two ones so i recalculated everything with a one ohm target to find the new properties of the track the next thing i had to figure out is how to make the pcb more rigid although the first pcb had an aluminium core it was still bendy it also expanded with heat and the air slots were creating a temperature difference which was creating a problem for small sized pcbs so i took the decision to remove all the slots and make the pcb a little bit thicker this would obviously increase the thermal mass but i tried to mitigate this by selecting aluminum with better thermal conductivity my next goal was to design a beautiful board using altium designer i decided to go with a heating area of 12 centimeters diameter which is supported by an air circular ring to hold the stand off feet this had to have exposed copper so that can be kept at a cool air temperature passing the thermal track within the circular outline was a little bit tricky but altum's interactive length tuning feature made things really easy but also let me add some warning signs on this little screen for extra safety if you'd like to test this pcb design software for free you can click the link in my description and if you're already an altum user or would like to purchase a license you can get 30 percent off pcb friday actually tastes good i know that having a circular design weighs some area but i think it looks way cooler than a squarish one the aluminum backside of the pcb is also covered in solder mask this will avoid any shorts with the top connector i will talk about this connector and why i made it the way it is in the temperature controller video but for now let's just see if this pcb hot plate works the track resistance was right on target so my old power supply was not going to supply enough current so it was time to order a new one this linear programmable monster has two channels and one of them can output 360 watts which would be more than enough for a little heater i connected my pcb hot plate and started measuring the temperature against the voltage this is the full result and as you can see at 12 volts it goes to around 195 degrees celsius which is just perfect because i only want to reflow some low temperature solar paste remember that these aluminum pcbs are recommended to operate below 250 degrees celsius so we are still in the range now i posted a photo of the specific on my social platforms and some people suggested that if i make a black solder mask it would absorb heat faster thus making it more efficient so let's test that this matte black pcb also looks cool but i think the purple one stands out more but if it's more efficient it would change everything i repeated the voltage versus temperature test and the same maximum temperature was reached then i tested the two boards against time starting at 0 volts room temperature and then instantly powering them with 12 volts i thought that the black solder mask pcb would reach the temperature quicker but i was wrong so based on these tests i'm going to stick with the perfect purple the exposed copper on the outer ring also worked because its temperature was much lower there was no sign of mechanical bending during this test but things quickly changed when i tried to overpower the thing with 360 watts 30 volts 12 amps test in three two one so it's safe to say that the voltage should not exceed 12 volts the next step is to reflow some boards to verify its purpose but before we do that i want to solve one last design problem the peak power of the specific hot plate is around 132 watts which slowly starts dropping as the track resistance increases with heat so the exposed copper on this connector is kind of dangerous apart from the safety aspect soldering anything to aluminium core pcb is really irritating because its thermal capacity would make your soldering iron weak connecting the wrong wire could also create unnecessary voltage losses so i think i'm going to eliminate all the wires and instead flex things up with a harness this pcb harness has one ounce thick copper the 3x are 7.6 millimeters wide connected with the vials on two layers i attached it to the hot plate using nylon walls it looked like it needed to be a little bit longer but it handled the current like a jump so i think then start testing reflow [Music] here we go [Music] yay sweet it's not my best stenciling job but the update works now remember that we're still missing the controller here so we're not following the temperature reflow and profile but powering it with just 11 volts gets the job done now as a final conclusion some of you have been asking me if i'm going to make this kit available on my website and to be honest with you i was planning to do that but the pcb failed one final test i left it poured with 12 volts for a couple of hours and the solder masks started discoloring this problem can obviously get solved by having a darker solder mask i tested the black one and it didn't do it but this discoloring problem shouldn't have happened with the ratings i've got so i reached again to my pcb manufacturer and turns out there was a misunderstanding because they sent me the data sheet and the tg value is specified to be 130 degrees celsius so the 250 degree celsius limit they gave me before was for short-term like during soldering the board is obviously still functional because it's only a single layer and doesn't include any vias so the dj rating should not affect it that much but it's still out of spec this kind of a bomber but there are other options left on the table which i'm going to experiment with in version 3. so if you want to keep updated on this project make sure you stick around bye [Music] turns out it's not a non-stick

Channel: Carl Bugeja

Views: 119,210

Keywords: arduino, diy, how to make, raspberry pi 4, pcb design, altium, design, engineer, simple, easy, science, technology, pcb, arduino projects, carl bugeja, electronics, circuit, microcontroller, circuit design, open source, pcb heater, reflow, reflowing a pcb, pcb reflow, soldering, solder paste, Reflowing a PCB with a PCB, automatic reflow, heat, heater, hot plate, heat bed, how to solder, soldering techniques, aluminium pcb, greatscott, reflow soldering, The Best way to Solder, DIY or Buy

Id: ZChSbpBbrt4

Length: 7min 40sec (460 seconds)

Published: Thu Sep 23 2021