How to save word file to high resolution PDF/A for archive on a mac

 Step 1:

In word, choose File -> print

Step 2: 

In the print dialog, go to the left lower corner, open the drop-down menu next to PDF and choose open in Preview

Step 3:

When the file is opened in Preview, go to File -> save

Step 4:

Choose create PDF/A

Done!!!!

The resolution of the document created this way (right) seems to be better than what created on a Window computer (left). No images were blacken.