The method of automated evaluation of the deformation of the printed circuit board

Increasing the mounting density of printed circuit boards, reducing the size of mounting and transition holes, and the size of the contact pads lead to an increase in the requirements for the positioning accuracy of the elements of the printed circuit board. This requirement becomes especially important in the production of multilayer boards, in which the mismatch of layers can lead to an incorrigible manufacturing defect. During the production process, the composite material of the base of the printed circuit board is deformed, leading to a significant displacement of the PCB elements. The presence of deformations can lead to several incorrigible defects, namely: removal of conductors, departure of contact pads, changes in the geometry of the edge of the printed circuit board, rupture of conductors and others that do not allow the manufacture of high-class precision boards. The paper analyzes the causes of deformations of printed circuit boards, considers the main types of deformation of printed circuit boards, the primary methods for measuring their deformation, offers a simple method for assessing the degree of deformation of a printed circuit board because of chemical, thermal, mechanical influences, and their combinations during the manufacturing process. The method involves obtaining an image of the printed circuit board before each stage of the technological process and comparing these images with the reference image received after the through-hole drilling stage. The method allows to evaluate of the deformation after any technological stage, is invariant to the deforming effect.