Preliminary assessment of the stability of thin- and polymer thick-film resistors embedded into printed wiring boards

Embedding passive components into multilayer printed wiring boards (PWBs) meet electronic device requirements concerning the necessity of saving the surface board area for active elements, reducing board’s size, improving device functionality and safety as well as overall product cost reduction. Since embedded components cannot be replaced after the board is completed, a long term stability and reliability are the important concerns for manufactures.This paper presents the results of examinations of embedded thin-film NiP resistors and polymer thick-film resistors during their continuous operation and the influence of temperature on the resistance values after the simulation of a lead-free soldering process and after the temperature cycling test (−40 ˚C/+85 ˚C).

► Climatic and functionality tests of thin- and thick-film resistors were made.
► The tests pointed on differences in the stability of thin- and thick-film resistors.
► The results indicate the importance of protective coatings of resistor’s Cu contacts.
► Huge raise of thick-film resistors resistance with unprotected contacts was noted.