A Study of 0201 's and Tombstoning in Lead-Free Systems, Phase II Comparison of Final Finishes and Solder Paste Formulations

摘要

Tombstoning, the phenomena where a chip component stands up on one end during the reflow cycle, is well-documented and understood in tin-lead systems. It is reported to occur more frequently in lead-free systems, and smaller components are at greater risk than larger ones.A comprehensive DOE was undertaken to characterize tombstoning of 0201 components in different metallurgical solder systems. Factors included pad geometry, board finish, stencil geometry, solder paste type, print and placement offsets, and reflow profile and atmosphere. The experiment was divided into two phases; the results of Phase II are analyzed and reviewed in this document.