Monitoring micro-mechanical changes in electronic circuit boards with digital holographic interferometry

The micrometric changes over the size of the objects produced by the temperature variations can create deleterious effects; the decoupling of soldering points in electronic circuits is one of them. In this work, we present a system based on digital holographic interferometry to quantify the magnitude of the changes produced on an electronic circuit board as it operates at very low electric currents. For the system to work, two digital holograms of the object are registered for different temperatures. These holograms are reconstructed numerically in a computer by using Fresnel's approximation to make a phase difference map. This map is converted into micrometer size variations by means of a lookup table. The implemented system allows for determining mechanical deformations in the range of 0.5–4 μm for a regular electronic circuit board drawing an electric current from 10 μA to 50 μA.