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Les defines solderability and troubleshoots cleaning process problems.
Q: What is a "dry joint?" Why is it important that a circuit board have no dry joints?
A: To achieve a solder joint between two mating surfaces, liquid solder must wet and flow over those surfaces to form a metallurgical bond. The IPC-T-50 Terms and Definitions document defines solder wetting as "the formation of a relatively uniform, smooth, unbroken and adherent film of solder to a basis metal."
In the industry, the term dry joint refers to a condition where the solder does not wet and flow on the pads of the printed wiring board and the component terminations. Instead, the solder beads up, similar to the way water does on a freshly waxed surface. Dry joints do not form robust metallic connections that will reliably carry electric current. Dry joints generally result in no connection or an intermittent connection. In soldering technology, the term used to describe the dry joint condition is "non-wetting" or "poor solderability."
Solderability refers to the characteristic of the surfaces being soldered and the ability of a metal surface to be...