Micro‐via approaches for reducing solder voiding

Abstract

PurposeThe purpose of this paper is to evaluate the influence of microvia design on solder joint reliability and to present a printed circuit board (PCB) microvia design approach capable of reducing or eliminating voiding in solder joints.Design/methodology/approachFive different types of via‐in‐pad designs were incorporated into a test vehicle and their performance evaluated using a variety of standard reliability tests.FindingsSolid vias, composed of 99.5 percent pure copper can be used to eliminate voiding in solder joints. Such vias are also much more robust than those employing metallic paste or other filled materials. Solid vias with flat surfaces have been shown to be able to meet the requirements of common reliability test standards and to offer a process compatible with traditional PCB manufacturing.Research limitations/implicationsThe occurrence of voiding in solder joints has been shown to be significantly influenced by microvia design. Although a design is reported for reducing/eliminating voiding, other factors that can cause voiding should be investigated. Also, further extended accelerated reliability testing could be undertaken to determine comparative long‐term reliability.Originality/valueSerious voiding in solder joints is a major threat to the quality and reliability of electronics assemblies, mainly due to its role as a stress concentrator and particularly with the move to lead‐free assembly. Methods for reducing and eliminating the occurrence of voiding are needed by electronics assemblers and this work proposes one such method that can be implemented at the circuit board design stage.