Attack on Titan Military PCB Badge

Hey, everyone what's up!

So here's something cool, a PCB Badge themed after the military police regiment from Attack on titan.

For those of you who don't know what that is, attack on titan is an anime set in a world where humanity lives inside cities surrounded by three enormous walls that protect them from the gigantic man-eating humanoids referred to as Titans.
The Military Police Regiment is one of three regiments in the show, they are the primary police force within the human territory. Not only do they maintain order, but they also serve as the king's guard.

That's pretty much the exposition, now to prepare a PCB Badge based on their emblem, I search its black and white image and then imported it into my PCB Cad Software.

To do that I had to change its format from JPG to BMP and then import it as an Outline or silkscreen or another layer.

placed the LEDs on the backside along with an Attiny13A which was in SOIC8 Package along with a mosfet as switch setup and a few other components.

To power this badge, I have used a coin cell holder onboard which provides 3V to LEDs and MCU.

• PCB (which was provided by pcbway)
• 1206 LEDs x 6
• AO3400 Mosfet x 1
• 10K 0603 x 2
• 1R0 1206 x 1
• Attiny13A SOIC8 x 1
• Coin Cell holder CR2032 x 1
• THT Switch x 1

Here's a neat trick, instead of placing LEDs in the right orientation which should be like this, I placed LEDs inverted.

why?
well.. by placing LEDs in an inverted position, the led light would face the PCB. if you look closely, I've removed the solder mask from the TOP side and bottom side so the LED glows from the bottom side will be visible from the TOP side.

on the top side, there's an art layer that contains the military regiment logo and I've placed LEDs exactly below that logo so when the LEDs are turned ON, their glow can be seen through the art layer.

I've done this same thing of removing solder masks in one of my previous badge projects which were this-

https://www.instructables.com/Kawaii-PANDACORN/

The idea here was to remove LEDs from the top side and place them on the bottom side but their glow should be visible from the TOP side to increase the aesthetics.

To get started, I first imported the military regiment emblem BMP image into my OrCAD PCB suite.

I prepared a simple setup that consists of 6 LEDs in parallel connected with an N channel mosfet which is controlled by an Attiny13a. the whole setup is powered by a coin cell.

after finalizing the schematic, I prepared the PCB in which I've placed all the components at the BOTTOM layer. on the TOP side, I placed the art layer which consists of the BMP image added as TOP Silkscreen.

About the LEDs, originally I wanted to use the 0805 package led in this project so I added LED in the 1206 package.
I added a bigger package pad in PCB to make the inverted soldering job easy but I didnt realize that because of the covid situation, getting 0805 LEDs is pretty hard so instead of using them I used the 1206 package LEDs.

I uploaded the Gerber data to the PCBWAY's quote page, I choose a green solder mask for this project as the garrison badge is green colored.

I received PCBs in a week and the overall PCB quality was great, which was expected as PCBWAY always offers quality stuff.

On the TOP and BOTTOM sides, I've left openings in the solder mask layer. Making this in CAD software is an easy feat but practically speaking, it's pretty hard to manufacture but pcbway made this with no problem whatsoever.

I've been using their PCB service for a year now, and my review of them is still the same, quality of PCBs is always high which is a plus point. PCBWAY, well done you guys!

Check out PCBWAY for getting great PCB service at a less cost.

During the PCB Designing process, I added an SMD Pad for soldering a brooch pin onto the Bottom layer but that brooch pad contains a design outline layer.

The outline layer is the cutting region so this whole rectangular area got cut down along with the actual outline of PCB which left this void in the PCB.

this removed the brooch pin pad completely but on the bright side, I now have a big void to attach a keychain with this setup.

SOLDER PASTE and COMPONENT PLACEMENT

To start the assembly process, I first applied solder paste to each component's PADs and then pick and place each component in its assigned place in the right order.

HOTPLATE

After adding components to their location, we carefully lift the PCB and put it on an SMT hotplate.

I'm using my DIY SMT Hotplate, learn more about it from here-

https://www.instructables.com/DIY-SMT-Hotplate-Pro...

Hotplate heats the PCB from below up to the solder paste melting temp, as soon as the PCB reaches that temp, solder paste melts and all the components get soldered to their pads.
we lift the PCB and then place it on a cooler surface for a little bit, to cool down the heat of PCB.

After reflowing the SMD Components, we start adding LEDs to their pads

we have to add LEDs in an oriented position, which means that we have to turn the LED 180 degrees and solder it to the provided pads one by one with a soldering iron.

Precaution here is to not overheat the LED or it will melt, just be quick and use a lower temp like 280°C to melt the solder paste or solder wire.

Now we place the remaining THT Components which were the coin cell holder and THT switch.

and the assembly process is done.

To flash the Attiny13A, I used my previously made Arduino as isp programmer to burn the bootloader of the attiny MCU and flash the code in it.

As for connecting the attiny with the Programmer, I added a SOIC8 Clip to the programmer. we clip the IC from the top side and then connect them.

• I added attiny's SPI Pins to D10, D11, D12, and 13 which are the SPI Pins of Arduino.
• then we go to the Arduino IDE
• add the core files for the attiny.
• select the board which is in my case Attiny13
• choose the right programmer (Arduino as ISP)

• then burn the bootloader, wait for a few seconds and you will be greeted with a "DONE BURNING BOOTLOADER MESSAGE"
• after this we open the sketch that we want to upload, then we go to sketch menu, and hit upload using programmer and our code will get uploaded to the attiny13A.

here's the result of this built, a nice PCB Badge that looks awesome.

I liked this idea of soldering LEDs upside down to make them glow in the opposite direction to illuminate the front side of the PCB.

Also, I've made this circuit in such a way that if I want to drive LEDs directly from the supply without adding MCU and mosfet, I just had to short R6 and just add a current limiting resistor along with Coin Cell holder and THT Switch.

To make this minimal version, I first added LEDs manually like before in an inverted position and then add the remaining THT components which were switch and coin cell.

We plug the 2032 coin cell in the coin cell holder and turn on the switch.
the result will be a minimal Badge with 6 inverted LEDs that illuminate the Art on Topside.

the only difference between this and the Attiny version is the programmable LEDs that can blink or fade.

this is it for today guys, thanks pcbway for supporting this project, you can check out PCBWAY for getting great PCB Service at a very economical cost.

Thanks again and I'll be back with another AOT badge next time!