Re-printed in partnership with ITM Dull solder joints Dull (non-shiny) solder joints are usually the effect of coarse grain structure in the solid solder joint (though there can be other causes). The more slowly a joint cools, the coarser the grain growth and, conversely, the faster the joint cools, the finer the grain growth and the […]
Re-printed in partnership with ITM Intermetallic Growth on PCB Where the tin-lead solder adheres to the copper of the lead (from plating) and to the pad (from hot air leveling or other pcb solder-coating method), an intermetallic of tin-copper forms. This is typically Cu6Sn5 or Cu5Sn6 and this intermetallic is what causes the solder to adhere […]
Re-printed in partnership with ITM Component Cracking Cracking of multilayer ceramic capacitors has been attributed to excessive heating rates during reflow. This may be somewhat mythical and what little cracking is still observed usually tends to be due to defects in the manufacturing process of the capacitor. Cracking of plastic-molded packages, such as QFPs and BGAs, […]
Re-printed in partnership with ITM PCB Delamination PCB Delamination is a separation between any of the layers of the base material or between the laminate and the conductive foil, or both. Process and design-related causes of PCB Delamination: Improper fabrication of the PCB Improper packaging of PCBs during shipping Improper storage of PCBs resulting in excessive […]
Re-printed in partnership with ITM Circuit Board Voids Circuit Board Voids are cavities or air pockets inside the solder joint formed by gases that are released during reflow or by flux residues that fail to escape from the solder before it solidifies. Process and design-related causes of circuit board voids: Improper solder volume due to improper […]
Re-printed in partnership with ITM PCB Nonwetting Printed Circuit Board Nonwetting is a condition whereby a surface has contacted molten solder but has had part or none of the solder adhere to it. PCB Nonwetting is recognized by the fact that the base metal is visible. It is usually due to the presence of contamination on […]
Re-printed in partnership with ITM PCB Dewetting PCB Dewetting is a condition that results when molten solder has coated a surface and then receded, leaving irregularly shaped mounds of solder separated by areas covered with a thin solder film and the base metal is not exposed. Process and design-related causes of PCB Dewetting: Solder paste flux […]
Re-printed in partnership with ITM PCB Bridging PCB Bridging Defects A bridge is comprised of solder that spans across two conductors that should not be electrically connected thus causing an electrical short. Process and design-related causes of PCB Bridging Defects: Excessive volume of solder due to improper pad dimension Excessive volume of solder due to improper […]
Re-printed in partnership with ITM Tombstoning PCB Soldering Tombstoning PCB Soldering Problems A type of open, known by a number of names (including crocodiling, surfboarding, Manhattan effect, drawbridging, Stonehenge effect, billboarding, etc.). This is a soldering defect in which a chip has been pulled into a vertical or near-vertical position with only one side soldered to […]
Re-printed in partnership with ITM Wicking Defects Defect: wicking A Wicking Defect is the flow of solder either up the lead of the component or along traces and possibly under insulation and through via holes. It robs solder from the interconnection, and is usually caused by uneven heating between the materials being joined. This is seldom observed in […]