Nixie tubes, which glow beautifully, require a higher voltage of about 175V or more to make them glow. I've made a boost-type DCDC converter that generates the high voltage from the 5V of the USB power supply.
In this article, I would like to mount the components on a second generation PCB that has been improved to be a little easier to use. The difference from the first generation is that the voltage control volume has been changed so that the voltage is higher in a clockwise direction, and the silk has been changed to make it easier to understand, adding to it. The features and performance are exactly the same.
Preparation for printing solder paste
Prepare the PCB
The target PCB is placed on top of the cardboard and surrounded by unnecessary boards of the same thickness to prevent the target PCB from moving.
Place the stencil and stab the thumbtack into the holes at the four corners to fix the stencil.
Prepare solder paste
I usually use lead-free low-melting solder paste, but this time I wanted a slightly higher melting point temperature, so I bought a new leaded solder paste.
I bought CHIPQUIK's TS391AX50, which, as before, can be stored at room temperature and the size of the solder particles are finer than those made in China, which are commonly used. DigikeyandIt is sold at Marz Parts.
Solder paste must be stirred well to make it smooth before using it. This solder paste was very smooth to begin with. It's obviously not as smooth as the one made in China.
Print solder paste
Put solder paste on the back of the stencil.
Print using an unnecessary credit card. I use the Marz Parts membership card.
I used thumbtacks to position the stencil so the solder paste printed beautifully without being misaligned.
CHIPQUIK's solder paste that keeps at room temperature is really good. It comes through the stencil well and prints beautifully.
The parts will be mounted with an electric vacuum pick HAKKO 394.
It is easier than tweezers to mount high-density components. It is one of the tools that you can buy without any loss.
Thanks to the electric vacuum pick, we were able to get the parts mounted in no time at all.
The temperature profile of the solder paste used this time is as follows.
Because it is leaded solder, its melting point is 183°C, which is higher than that of lead-free, low-melting solder. You need to raise the temperature up to a maximum of 235°C, the maximum temperature of your convection oven.
I use this convection oven.
The temperature setting can be changed in the middle of the process, making it ideal for reflow.
100°C for 1 minute to 150°C for 2 minutes to 230°C for about 1 minute, which is a nice temperature profile.
I was able to reflow the parts nicely without any standing up or manhattan phenomenon.
Using a handmade jig, we will check if the voltage is successfully boosted when the 5V is supplied. All 12 circuits worked properly.
The second generation Nixie DCDC has been completed!
Compared to lead-free solder, leaded solder has a shiny appearance and is very beautiful.