The Power supply board has finally been manufactured and now we have to 'populate' the board with components and make sure everything is working right. We're still waiting on one type of microchip to arrive from the suppliers and a...contact...of mine is arranging to have our batteries made to the perfect specification. Here's a look at just how small the board and some of the components are:
The dimensions of the board are 100mmx100mm (that's just under 4 inches square). The photo on the right has zoomed in a little on the components which we will be populating the board with. The microchip I have placed over its pads in the board, just to the left of the pen. Within the red circle is a surface mount capacitor. This is so small it came out too fuzzy to see, but it's roughly a 16th of an inch long and half again as wide. TINY! Thank goodness I don't have to get a soldering iron into that. The program which has helped me design this whole project will also generate what is called a 'pick and place' file. This can be entered into another type of robot which will place the capacitor and other surface mount components onto the board in the right place. There will already be a layer of solder plaste on the pads and the board is then heated in an oven. The solder melts then sets and presto! the components are in place without me having to go anywhere near them!
Just as another bit of interest - I explained how the footprints work that allow the program to know how many pins etc a component has. Well a lot of footprints also detail the height and shape of the part as well and DXP can generate a 3D image of what the PCB will look like once it is made. Here's a 3D image of the processor board. The large square microchip has 128 pins coming out all four sides and those pins are as little as the ones on the micro in the pictures above. Using the 3D feature has been extrememly helpful for me to visualise how the boards will mate together - the grey rectangles are connectors and they fit into more printed circuit boards. At the moment the robot will require four or maybe five of these boards and four processors just to get the job done. Wish me luck!