TAIPEI, Taiwan — A few weeks ago, analysts at a specialized technological lab put a microchip from China under a powerful microscope. Something didn’t look right.

       Figuring out where a tiny electronic chip was made is a bit like trying to authenticate a painting. A trained art appraiser can tell its provenance by brushstrokes, the signature, the chemical composition of pigments. For chips, details like the microscopic layout and material makeup of the transistors are telltale signs of which foundry produced it.