Recently I designed a new PCB for projects which is based around a super tiny SMD IC
its package is called 14 leads MLP while MLP stands for micro lead frame package and
14 leads means that there are 14 pins positioned all around the IC
Now I actually tried hand soldering this IC in place with the same techniques
I showed you in my how to solder properly video
But, as you would expect with such a tiny IC, it was pretty much impossible to create good contact with all the solder pads
To solve this problem. I also ordered the stencil for my PCB design and in this video
I will not only show you how to use it in order to successfully reflow solder my PCB
But while doing so I will also try out three different reflow methods
Which are: hot air, sand, and a reflow oven, in order to determine which one I would recommend
Let's get started
[music playing]
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First off in order to perform reflow soldering we need this
Which is called solder paste and it is basically a mixture of flux and solder
At this point we could use a flathead screwdriver
Or something similar to apply the solder paste on all of the PCBs solder pads
But needless to say this technique is rather unprecise
To get better results, I firstly used
Other PCBs I had lying around in order to lock the position of the target PCB in place
then I simply placed the stencil on top of the PCBs and aligned its holes with the solder pads of my PCB and
And once again secured it all in place with electrical tape
Afterwards, I added a bit of solder paste next to the holes and use something like a credit card in order to evenly
distribute the solder paste all over the stencil and
As you can see after
Removing it we get an even distribution of the paste all over our solder pads in a very precise way
beautiful
Next, I unpacked the components for the PCB and placed them, with the help of tweezers, onto their solder pads
most of them were pretty easy to position
But it required a bit of patience in order to get the main IC in position
nevertheless though after a few minutes all of the components were on the PCB and
It was time to reflow the solder paste
Now if we Google this particular solder paste then we can easily find its data sheets
Where we can find information about its reflow profile
which basically describes how hot the paste has to become for how long in order to turn into proper solder
Of course by using the first technique with hot air we cannot properly follow this profile
But I can set the maximum temperature to around 300 degrees Celsius
which is a bit above the maximum stated temperature of
250 degrees Celsius and
after deciding on a medium wind speeds
I slowly heated up the PCB solder paste
and components through hot air, and as you can see after only a few minutes
all the paste turned into proper solder connections
you can also see that it is easily possible to overheat a component and
I also had to touch up the IC solder joints as well as the USB type-c ports
But after doing that I have to say that all the solar connections look pretty decent and thus I continued by soldering
the rest of the THT components in place with a normal soldering iron
now before I test this board in order to find out whether all solder connections formed successfully,
I repeated the soda paste spreading component placing process in order to try out sand
this is one kilogram of the finest sand that I could find on the Internet and
My theory is that by filling up a normal pan with it and heating it all up with a normal stove
We should get an even heat distribution all across the surface of the sand and thus good reflow results
So I obviously have filled up a pan placed my PCB in the middle of it and started heating everything up
The only problem was that the sand apparently never reached high enough temperatures
That is why I tried a second attempt with a lot less sand
And as you can see this time the reflow process worked out just as planned.
I have to say these solder connections look promising, but
Just like before I had to remove a bit of excess solder from the USB type-c ports
Like already stated I will test the PCBs at the end
So for now, let's move on to the last
probably most professional technique
the reflow oven I
I got this one from the internet for cheap and
After inspecting it for a bit, it seems like a low-cost version that could do the trick
But if you take just five seconds to Google its model number
Then you quickly realize that it comes with a few flaws which are luckily pretty easy to fix
so I removed a couple of screws as well as its PCB tray and
Lifted up its top cover to reveal its insides
There I fixed the first big problem by removing the masking tape
Which would have created a horrible smell if being heated up
Instead I replaced it with Kapton tape, which is known for handling high temperatures well.
Next I added a temperature sensor to the control electronics
for the cold Junction compensation
And also used an FTDI breakout board in order to reprogram the control electronics with an open-source software
But if you want more information on this topic, then make sure to visit the websites that are linked in the video description
As soon as the new software seemed to work just fine.
I reassembled the oven and thus it was time for another solder paste spreading component placing run
Afterwards I placed the PCB in the middle of the oven tray and closed it up
The new firmware comes with a couple of reflow profiles
out of which I tried out the custom profile 2 and later the AMTEC Syntech-LF profile
In both cases the oven followed the profile lines decently and thus heated up successfully
But in both cases the temperature was apparently also too low
Because the solder paste did not reflow properly
so my crude solution was to select the custom profile one which basically heats up the oven without an end and
All I did was looking for the moment the reflow process took place, which was at around
270 degrees Celsius at which point I then quickly turned off the machine
And just like that, I got this beautifully reflowed board whose USB ports
I obviously also had to redo a bit
That means I finally got my three PCBs, all reflow soldered with different methods
at this point
I finally tested my boards and without revealing too much about my next projects
I have to say that all three of them work just fine
The only question remaining is what reflow technique, I would recommend
Well, if you got such a reflow oven
Then I would recommend this method
because it is the most accurate and professional one
At least if you program in a suitable reflow profile for solder pastes, which is easily possible
But if you got no equipment then I would recommend the sand methods
Because even though it can get a bit messy
It costs less than a hot-air station and you can also not easily overheat particular
components on your board with it
And with that being said, I hope you enjoyed this video
If so, don't forget to like, share, subscribe, and hit the notification bell
Stay creative and I will see you next time
