# Expanding your boards

Each of the boards has an area on the right hand side for adding an expansion board.

### 640 board

The expansion area on the blue 640 board has solder already applied to it to make it easier to add your expansion board.

![640 Motors](/images/640-expansionarea.png)

### ESCAPE board

The expansion area on the blue ESCAPE board has solder already applied to it to make it easier to add your expansion board.

![ESCAPE Expansion](/images/escape-expansionarea.png)

### SOAR board

The expansion area on the blue SOAR board doesn't have solder pre-applied, so adding an expansion board will to this will be slightly different.

![soar](/images/soar-450.png)

# Required equipment

To add an expansion board you will need a few tools and bits and pieces.

### Solering iron

I assume you already own a soldering iron, but in case you don't, we recommend getting an iron with a digital temperature control. They may be slightly more expensive than the soldering irons that just plug into the power socket but if you are going to be doing a lot of soldering then it's worth it in the end.

### Solder

We use Lead Free solder here, but if you prefer leaded then that should be fine as well.

### Flux pen

A Flux pen is a *must have* item really - you will never regret buying one. We use this one - [Electrolube SMF12P Surface Mount Rework Flux Pen 12ml](https://www.rapidonline.com/electrolube-smf12p-surface-mount-rework-flux-pen-12ml-single-87-4426)

### Flux remover

Flux, whilst useful, can leave nasty sticky areas on your board. You should always use flux remover on your board once you've soldered it to remove it and make things nice again.

We use this one - [Ambersil 30216-AB Flux Remover 400ml](https://www.rapidonline.com/ambersil-30216-ab-flux-remover-400ml-87-7352)

### Tweezers

A good set of tweezers so you can hold the exapnsion board.

# Adding your board

The expansion boards have small notches on the side (that are called castellated vias) that we need to solder to the pads on the main board. Soldering these maybe new to you and seem a bit daunting - don't worry though as it's not as difficult as it looks.

### Sparkfun tutorial

We recommend watching this video by Sparkfun before you get started as it goes through the process we'll describe later in a lot of detail.

<iframe width="560" height="315" src="https://www.youtube.com/embed/rGvvwXrv310" frameborder="0" allowfullscreen></iframe>

### Expansion orientation

You'll notice a small white dot next to the expansion area on your main board. If you place the expansion board along side you should be able to see a similar white dot in one corner (labelled **Z**). 

![orientation](/images/expansionorientation.jpg)

When you place the expansion board on the main board, you should line these two dots up.

### Soldering the first pad

Add some flux to each of the pads on your main board. 

If your main board is the SOAR board then you will need to add a bit of solder to one of the pads - we recommend the right hand pad on the same row as the white dot. Once you've added some solder, add some more flux over the top of it.

### Attaching the board

Now add some flux to the edges and pads of the expansion board. Once you have done that, pick the exapnsion board up with your tweezers, making sure that it is still in the correct orientation.

Hold the exapnsion board on the main board and try to line up the small notches on the expansion board with the pads one the main board.

Once you are happy, apply some heat with your soldering iron to the first pad you picked earlier and you should see the solder flow and join the two boards together.

Remove the iron and let the joint cool down, then let go of the exapnsion board with your tweezers.

If the board is slightly mis-aligned then you can apply some more flux to the first pad, re-heat it with your soldering iron and move the exapnsion board with your tweezers until it is lined up.

Again, make sure you remove the soldering iron **before** you let go with the tweezers so the solder hardens and keeps the expansion board in place.

### Solder the rest of the pads

Now the first pad is soldered and the two boards joined, it's time to solder the rest of the pads. Make sure you have flux applied to each pad and notch (add some more if you are unsure - it won't hurt).

Melt a small amount of solder on the end of your soldering iron and touch the next pad, you should see the solder reflow and the flux will pull it to the expansion board and join them.

Continue with each pad in the same way (with a little bit of solder on the end of your iron). Leave the pad next to the white dot until last.

### Ground pad

The ground pad ( the one next to the white dot ) is the trickiest to solder as it is connected to the *ground plane* on the main board and will take a bit longer to heat up.

Add more flux to that pad (and the exapnsion board pade and notch) and, with some solder on your iron, place the tip so that the end touches the expansion board and a bit of the body touches the main pad. 

You'll need to leave it there for a little bit longer than you did with the other pads, but it will heat up after a few seconds and you'll see the solder flow in the same manner.

![Expansion edge](/images/expansionedge.jpg)

Congratulations - you have now attached your expansion board. 

![Expansion side](/images/expansionside.jpg)


