suggestions for attachment to cut wafer NFC chip (or very low cost SMD NFC chip)

[chaseadam]

I have a project which I want to showcase the antenna of an NFC tag in a specific dimension on a custom PCB.

It appears all passive NFC chips (except a few oddballs like NFC+i2c) are bare die. An example chip is the NTAG210/212, but there are many clones. You can buy wet or dry "inserts" or stickers with what appear to be very thin tinned copper antennas. Anyone know how they attach to the antenna?

The method for connection to the antenna was not obvious to me after ripping a "wet insert" apart and flipping the bare die chip over.

There are 4 (convex) intents on the antenna underneath where the chip sits. I am guessing this is the electrical connection.


It appears to have a small amount of epoxy on it. Is it possible the epoxy is making the connection? (Seems unlikely)
Is it a "die bond" of the antenna foil directly to the chip? The convex intents may imply it is not directly bonded as I would think a direct bond would be concave.

Any suggestions on very low cost SMD style NFC Tag chips?

Seems crazy, but any obvious problems with "harvesting" the chip from an insert and bond (solder?) to the larger aluminum antenna lead after cutting the antenna? Seems I can get solder to attach to it... (obviously the antenna it is attached to would need tuning to take the lead into account)

[chaseadam]

Best option I found to date for SMD packaged NFC Tag chips are the "enhanced" NT3H2111 with i2c ($0.67@1k) and NTAG213F with field detection ($0.33@1k)

[free_electron]

The chips have copper pillars. They are friction welded (ultrasound)