Wafer level chip scale assembly considerations

The GaN transistors with the solder bars are in a package I’ve never seen before. Can these be mounted by normal pick and place equipment, or do they have to be encapsulated in order to use?

Yes, these transistors can be mounted with standard equipment. They are put directly on a PCB. Here is an application note, it has many diagrams of what they parts look like when mounted. https://epc-co.com/epc/Portals/0/epc/documents/product-training/Appnote_GaNassembly.pdf. To answer your question: most companies don’t encapsulate the EPC GaN FETs. Some do coat the boards, and/or use underfill, but these aren’t required. Quick notes: 1. These transistors sit a bit above the board (as in the diagrams and photos) 2. The board design should have solder-mask-defined pads (as covered in the app note) and 3. Standard reflow. As recommended by the manufacturer of the solder you use. There is more about solder in the app note