We have sent our third motherboard to production, after many hours working on it. It will allow to have 128 MB of RAM and the possibility to plug different screens (the sharp, and a color TFT one). For this board we used a BGA chip, which is really new for us, and make things more complex. In particular, we don’t know how the soldering process is going to work.
This time we had to create a Kicad Library for the IMX233 BGA, because it did not exist yet. Let’s hope that it won’t be a supplementary chance of failling! We have adapted the length of the tracks to the RAM thanks to our kicad branch ( here ). The whole circuit is a lot smaller: 5cmx5cm.
Once we had received the board we decided to solder it using the usual soldering technique with the frying pan or almost. Indeed, we first placed all the components except the imx233, and then heated the board so that they don’t move anymore, and so that we can place the imx233 more easily and precisely. We have put some flux over the BGA pads, then we placed the imx233 as precisely as possible, then heated again.
Once the board soldered, we tested its behavior, and then, Ô miracle, everything worked well almost directly. Linux boots again and again! Nothing should now prevent us from having a second prototype in the following weeks.
It’s possible to make BGA boards with Kicad and a frying pan!
After soldering the second Ram chip the board works with 128MB of RAM. However it requires a u-boot configuration ( see https://community.freescale.com/thread/335883 )
We discovered a bug in the electronic circuit. We’ll correct it and then publish Kicad sources.