Detection of defects in printed circuit boards by the acoustic emission method

Abstract

Objectives. Defects in the form of layering may occur during lamination in the production of multilayer printed circuit boards (MPCB). These defects cannot be detected by optical and electrical methods of output control. However, they can lead to breaches of the mechanical mode of operation and failures while running radioelectronic devices. In order to detect such defects, the acoustic emission (AE) method is proposed. This is based on the occurrence and propagation of acoustic waves in MPCBs caused by the presence of defects. The aim of this study is to investigate the possibility of using the AE method to detect defects in multilayer printed circuit boards. These defects can occur, in particular, in the lamination process.Methods. A mechanical processes modeling program (for research on the MPCB model) and various samples of two-layer printed circuit boards with pre-introduced defects (for experimental studies) were used to study the propagation of acoustic signals in the MPCB in the presence of defects. A solenoid mounted on the MPCB was used as a source of acoustic signals, while a piezoelectric sensor was used to receive signals. Data processing was carried out by comparing AE signals obtained for a serviceable MPCB sample and for MPCB samples with defects.Results. Simulation of the acoustic signal propagation in MPCBs in serviceable and faulty (with a rectangular defect in the form of delamination) states was carried out to show the difference in the received signals at the sensor installation point. Experimental studies were also conducted to examine the AE method applicability for detecting defects of various sizes and quantities.Conclusions. The studies demonstrated that the AE method allows the presence of defects in MPCB occurring during the lamination process to be detected effectively and reliably. This study proposes a new approach to non-destructive testing of MPCB using the AE method. This method significantly increases the reliability of MPCBs and the efficiency of their production processes.