We’ve been using the name Falstaff to refer to our first prototype of the oPen. Falstaff will have three printed circuit boards (PCBs) to connect all of its electronic components: a processor board that has the processor, RAM, and ROM; an input/output board that has the buttons and lights; and an image-sensor board that, you guessed it, holds the image sensor and illumination lights.

Here’s a picture of Rev 1 of the Falstaff processor board which was completed on Wednesday. This board has eight layers of electrical connections through wires that are only 3 thousandths of an inch wide. The next step in the manufacturing process is to solder all the components onto this “bare” board.

Why isn’t this PCB green?

The color of a circuit board comes from the outer layer which is called a “solder mask.” The solder mask covers all the wires to protect them, but leaves holes where the components are soldered to the board. Without solder mask, PBCs are a dirty-yellow color. For some reason, most circuit boards are made with green solder mask, but the manufacturers have many colors to choose from. Since future revisions of this board may look very similar, it is handy to make each revision of the board a different color so that it is easy to tell them apart.

By Ian MacDuff