Transferring data over induced coupling

[Bruce]

But 0402?

Stuff just wouldn't fit otherwise, and we needed the free space for the 418MHz UHF & 125kHz RFID parts. There's a UHF antenna for the Linx RF transmitter on the back of the board just behind the Primeport logo.

These RF parts need x amount of clearance from board components, so we had to go with 0402 to squeeze everything into a keyfob enclosure on a board 1/3 the size of a credit card. The CR2032 battery holder & UHF antenna sucked-up 50% of the
board space.

The board photo looks big, but it's definitely not.

We do all SMD placement under a lab microscope, and beyond the initial prototype, we do all soldering with a RoHS comlpiant reflow oven, and lead-free solderpaste screened boards.

We use the Gold-Flow GF-B-HT reflow oven and a zoom stereo trinocular microscope mounted on a boom stand for SMD placement. Photos attached.

RF design is a whole new world, and if it's not spot-on, you ain't getting that FCC stamp of approval. So you allow for whatever clearance is needed for the RF stuff.