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62 PCB007 MAGAZINE I JUNE 2025 figure in the printed circuit board (PCB) industry who passed away in 2020. He had a long and influential career at DuPont, where he contributed significantly to the advance- ment of electronics materials and processes. He was widely recognized for his technical expertise and dedication to knowledge shar- ing, particularly through numerous technical publications, seminars, and training sessions. For nearly two decades, he served as the technical editor of a primary industry publica- tion, where his "Tech Talk" columns (the pre- decessor of my own) offered practical insights into PCB fabrication challenges, including the topic addressed in this article: via voids and failures. e following is an overview of sev- eral of Karl's insights on via reliability. Understanding Hole Voids in PCB Fabrication Karl wrote that hole voids, also known as con- ductor via through-hole voids, are a category of defects in PCBs that occur due to insufficient or missing metal coverage inside the conduc- tor via. ese voids can significantly impact the electrical reliability and structural integrity of the circuit board. He stated that these defi- ciencies generally stem from two causes: inad- equate metal deposition within the via or the subsequent loss of metal aer initial deposition. Inadequate metal deposition can result from faulty plating parameters such as incor- rect bath chemistry, improper agitation, sub- optimal current or current density distribu- tion, or insufficient plating time. Addition- ally, metal deposition can be obstructed by physical interferences like gas bubbles, par- ticulate contamination, or organic residues. Conversely, metal loss can occur due to chemical etching or mechanical failures such as blow-holing, cracking, or flaking of metal deposits. Understanding the full range of causes requires a methodical approach to ana- lyzing defect types, recognizing void patterns, and tracing issues back to their root causes. Figure 1: Blow holes and wedge voids.