I love the Arduino UNO with the DIL 28 ATmega328. He is easy to replace and all my projects are equipped with it. But constantly either the flash memory, the RAM or both is too small. Therefore, I have developed a replacement that provides 8 times more memory. For this I went into the microcosm of the PCB construction and impressed an ATmega2560-16CU in the smallest possible layout.
Here is the PCB layout. There are 4 layers. The board is 12 * 53 mm in size, the ATmega2560-16CU CBGA with 100 pins is only 9 * 9 mm.
I made this really tricky PCB with Sprint Layout 6. I went to the limit of sprint layout feasible.
In Europe, the MC costs 14 euros if you're lucky. Making the PCB is individual in price, but it's always about the 15 Euro Plus tax.
At first I tried to solder the PCB in my home with the iron. Then I used the kitchen stove. After 20 failed attempts, the pattern shown in the picture is the first one that worked.
On an Arduino UNO I can now use 256 KB flash, as well as 8 KB SRam and 4 KB EEPROM. For my next project I need fell memory.
The first .......
This is the PCB, you can see how small the structures are.