June 6, 2022

National LH0042CH - hybrid opamp with FET frontend : weekend die-shot

National LH0042CH came from the time when you could not have had high-performance BJT and FET transistors on the same die. Even in 2022 there is still room for hybrid opamps, for example external JFET frontend still allows one to reach lower noise compared to integrated IC.

Main die size 1053x825 µm, frontend die 567x520 µm.

Main die:

Frontend die:

Packaged on a tiny ceramic interposer that fits into TO-99. All Gold-colored parts are 100% Gold. TO-99 pins though are only Gold-plated.

And now lets see it under SEM. Here we can see saw marks that only go half way in thickness, and crack going all the way.

Looking at the crack, FET die also seems to have different crystallographic orientation of Silicon substrate.