Document contains at least one immense term (for a searchable array)

We have a field which is an array of not_analyzed terms. These terms need to be searchable, but not analyzed. However, when the number of items in the array exceeds a certain number, we hit an exception:

"Document contains at least one immense term".

I know the field can be set to analyzed to be broken up, but not sure how to do this with an array. Any help would be greatly appreciated!