{"id":2635,"date":"2025-06-13T06:06:52","date_gmt":"2025-06-13T06:06:52","guid":{"rendered":"https:\/\/blogs.lcsc.com\/blog\/?p=2635"},"modified":"2025-08-05T07:30:52","modified_gmt":"2025-08-05T07:30:52","slug":"avoid-tombstoning-in-pcb-assembly-causes-and-analysis","status":"publish","type":"post","link":"https:\/\/blogs.lcsc.com\/blog\/avoid-tombstoning-in-pcb-assembly-causes-and-analysis\/","title":{"rendered":"Avoid PCB Tombstoning in Assembly: Causes and Analysis"},"content":{"rendered":"

What Is PCB Tombstoning?<\/span><\/b><\/h2>\n

Tombstoning PCB, also known as the Manhattan effect or crocodile effect, is a common defect in Surface-Mount Technology (SMT) assemblies.<\/span><\/p>\n

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Tombstoning effect in SMT: chip resistor standing upright on PCB during reflow soldering (Image source: online)<\/figcaption><\/figure>\n<\/div>\n<\/div>\n

It occurs when one end of a surface-mounted component lifts vertically from the PCB during reflow soldering due to uneven soldering. This issue not only leads to open circuits but also affects production rate and product reliability.<\/span><\/p>\n

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SMT tombstoning defect: chip capacitor standing upright on PCB during reflow (Image source: online)<\/figcaption><\/figure>\n<\/div>\n<\/div>\n

What Causes PCB Tombstoning in Assembly?<\/span><\/b><\/h2>\n

Tombstoning happens when there is an imbalance in mechanical and thermal forces during soldering. As the oven temperature increases, the solder paste melts and solder joints form. However, if the solder paste is applied unevenly, heats up at different rates, or doesn\u2019t adhere properly, the forces on each side of the component become unbalanced. The imbalance can cause one end of the component to lift up, making it stand upright on the PCB.<\/span><\/p>\n

Key Contributing Factors<\/span><\/b><\/h3>\n