How to use both LGA and castellated pins for IMX6UL-cc ?


We are currently transitioning from the old “Digi ConnectCard™ for i.MX28” to the ConnectCore 6UL.

For generating the pin layouts, we use the “Smart IOmux” software. It forces us to choose between two options : castellated or LGA.

But, because we are completely new to LGA technology (we still use Eagle for routing), we would like to use the castellated mode for most of our needs (UARTS, USB, …) and to use LGA only for an additional UART need.

The goal is to minimize errors and the number of prototypes we will need to get it right. It is the first time for us using Yocto too.

Is it possible to use LGA and castellated at the same time ? (and does it make sense ?)

We tried to edit a project using IOmux castellated mode, then save the project in the XML format, then edit the file with notepad to activate “lga” mode in order to add our additional UART. The edited file correctly loads in LGA mode, but adding this extra UART breaks all the previous settings.

Is this just a limitation of the IOmux software, or is there some physical limits forcing us to choose between the two modes ?

Thanks in advance,
Mathieu Galle for Vitirover, a robot mower company

Mixing LGA and castellated pads is not a good idea and we strongly advise against it.

Normally castellated pads need more solder paste and sit higher than LGA. The risk is that you will end up having no contact with LGA.

I’ve seen nothing but problems when people try it and we do not support it.

Thanks a lot, we avoided a failed prototype with your answer. We will only use LGA.