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Brain Board Soldering Instructions (Preview)

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Buzz with Brain Board

What is the Brain Board?

Buzz’s Brain Board is an AVR ATTiny based microcontroller that you can program with the Arduino Development Tools.

The ATTiny for the Brain Board is pre-loaded with the Micronucleus Bootloader. The bootloader allows us to connect the board to a computer via USB. This allows us to download code known as sketches to the ATTiny chip on the board and do things like control Buzz’s eyes and his buzzer.

We can also use the light sensor and the touch sensor on the Brain Board for input.

For this lesson, we will be building our Brain Board. first.

You will need to do the following before you start soldering:

  • Read through the instructions first
  • Have Buzz soldered together
  • Have soldered once before (we highly recommend that you start with Buzz to get an idea of how to solder).
  • Review our “How To Solder” tutorials.

Soldering Is Easy one Page Guide

Advanced Soldering Tips:

  • Clean (and/or tin) the soldering tip before each soldering session.  It should be nice and shiny.
  • Put the soldering iron back in its holder dirty but clean it each time you pick it up to solder.
  • Shiny – hot!  After you solder a part, do not pick it up until it cools after a few minutes.
  • Solder flows to the heat. You need to heat up the pad on the PCB and the part you are soldering before you apply solder.
  • Less solder is better – no globs of solder on the parts.
  • Remove the solder first.  Then, take the tip away from the PCB pad heat.
  • Put your iron away dirty! Put it away with a glob of solder on it. The solder protects the tip and keeps it from oxidizing.
  • Take your time.  Don’t rush.
  • Have fun!

Don’t have the soldering tools or personal instruction?

No problem.  Click on the following link to find a Makerspace in your area.  Makerspaces are a great resource and often have soldering classes available.

If you are located in New Jersey, come to FUBAR Labs in New Brunswick.  They hold soldering classes every Sunday from 1:30 – 3:00 pm

Brain Board Complete

Brain Board Parts

Basic Layout

We already did this in the components lesson.  In case,you skipped ahead, lay out the components as they would be laid out on the board. This will help us identify the components correctly and later when we solder them to the board we can make sure we are picking up the right components.

Safety First

  • Put on Safety Glasses before soldering
  • Wash Hands after you are done soldering.

Resistors and Diodes

  • 1k5 ohm resistor
  • a 330 ohm resistor
  • two 22 ohm resistors
  • Two Zenner ZD3v6 Diodes
  • One IN4001 Diode

We will start with the resistors. Place each resistor and diode in the PCB. Make a “u” with the leads and press through. The component should sit flat to the PCB.

Resistors don’t have polarity.  There is no specific right to left (or up and down) orientation.

Diodes do have polarity. Pay attention to the markings on the PCB and place the diodes in with the mark in the same direction.


Soldering Tip

You can use tape to hold your board in place while you solder.


Check Your Solder Joints

Inspect your soldering work. If you see a joint that you are not happy with, you can hit it with a little more heat from your iron. The solder should wick in and make a chocolate “kiss” shape.  Resist the urge to add more solder.

If you look at your solder joint and there are gaps around the hole, then you do need more solder. Again, heat the pad and the lead and then add solder. It is easier to add more, than have to remove. Do not add to much.

When you are happy with all your soldering, clip the leads of all the components.  Hold the lead and clip them just at the top of the solder, not perfectly flush with the board.





  • 0.1 uF capacitor
  • 10uF capacitor

The 10μF we are using is the larger, round, capacitor and  does have a polarity and has to go in the board in a specific direction. You will notice one leg of the capacitor is longer, this is the positive (+) leg. The shorter leg is the negative (-) leg.

The 0.1μF Capacitor is a disc capacitor and does not have polarity and can go into the Brain Board in either direction.

When complete, inspect your solder joints and clip the leads. Make sure you hold onto them as they can fly far.

LED And Symbol

Brain Board LED

Soldering the LED

The 5mm LED is a Diode and polarity is important. LED stands for Light Emitting Diode.

The anode (long leg) goes into the ROUND hole with the + sign next to it.

Switch with Symbol

Switch Cut

Clipping and Soldering Switch

Before soldering the switch, the switch needs to have the three outer leads clipped.  Orientation doesn’t matter. Clip the leads, then solder in place. You can hold the switch in place with tape while soldering. Make sure the toggle faces out to the edge of the  board.

BrainBoard IR Collector Emitter


Solder Infrared Emitter Collector

The Infrared (IR) Emitter Collector looks similar to the LED we soldered earlier and like the LED has to go in the board in a specific direction.

  • long leg goes in the hole labeled E
  • short leg goes in the hole labeled C

Optional: leave about a 1/8″ of space between the base of the IREC and the board so that you can bend it facing forward.

IC Socket

IC Socket

Soldering IC Socket

Next, solder in the IC socket. Tape the socket in place. Make sure the half-round hole is near where the female header will go.

The pins of the IC Socket are thin and heat up fast. You do not want to overheat as you could melt the plastic socket. Also, make sure each pin has a good solder joint. Do not clip the pins.

DO NOT insert the ATTiny chip yet – we will do that after we finish the whole board.

Brain Board Battery Clip 20151107_104711

Soldering the Battery Clip

The battery clip is next. The indented side should hang over the edge of the board. Tape the clip in securely, turn over and solder. The clip is a large piece of metal it will take a little more to heat up before you can add solder.

CAUTION: the metal clip gets HOT when you solder to it and takes longer to cool down.  Remember: SHINY = HOT. 

USB Type B

Brain Board USB

Solder USB Type B Connector

Next, solder the USB Type B connector. USB has four pins plus a the shielded connector (the exterior) that needs to be soldered. Do not clip the pins.


Solder 10 Pin Female Header

One piece left to solder, the female header. This is how we will connect our Pi Pals later.  Like the IC socket, the header pins are thin and do not need to much heat. Make sure each pin has a good solder joint. No need to clip the pins. 

ATTiny on Brain Board

Insert ATTiny Chip

Now you can insert the ATTiny chip. Make sure the reference mark positioned at the top (the half circle) of the IC socket. To make it easier, we added a little mark so you can see the reference dot.

Insert it firmly, yet gently. Do not forcefully bend the pins. After you insert it, make sure all the pins are in the IC socket.

If one bends, remove the chip, and straighten the pin gently.  The chip should feel as it it set into the socket.

The Brain Board

WOO HOO! You are done! Give yourself a high five (after you turn off your soldering iron).  You have built your very own microcontroller!

Plug Buzz into your Brain Board. Buzz should face forward.

Next lesson we will connect the Brain Board to your computer to program it.


Lesson tags: Brain Board, Capacitors, Chip, Diodes, Kickstarter, Kit, Pi Pal, Soldering
Back to: Brain Board