I am using BGA package type of MCU, and it has ball pins on the bottom side. As I route the signal route, some of pins should be connected with unused pins without build-up method. The pins are not ADC. I wonder it will affect any operation on the chip or not.
I think my firmware will not take those pass-through unused pins, so it is not. But it is not general in artwork. Is there anyone who faced same case?
A is signal route I am using
B is unused pin, but I connect with A for pass-through
Other sides are blocked by other routes.
Jiwon
Best Answer
Some manufacuters document their pins as "Do Not Connect" and "No Internal Connection" rather than just "No Connect".
You should not connect anything to a "Do Not Connect" pin. It is likely to adversely affect the behavior and performance of your circuit. For example, it might put the chip into a test mode, or change the behavior of an analog circuit.
In principle, you can connect whatever you want to a "No Internal Connection" pin without adversely affecting anything. But you might want to consider whether you ever want to replace the chip you're using with an alternate part (a faster one or a cheaper one from the same family), or if it's possible the chip vendor will change the design in a future revision so that that pin is no longer "NIC".
If your chip's datasheet just indicates "No Connect", you might be able to get more information by asking the vendor's apps engineers, but it's probably safer to just not connect anything to that pad.