Shen Jin pcb board oxidation analysis and improvement methods?
It can be imagined that for the circuit board industry, the most common problem is the poor oxidation of the Shenjin pcb board. For this situation, Xintong is very concerned about the circuit, so the discussion group was established. The participants included quality, technology, and customer service. And suppliers, etc., to discuss and improve this issue. After a week of on-site observations and experiments, this issue has been comprehensively improved.
1、 Immature Oxidation Plate Photo:
2、the gold plate oxidation instructions:
The circuit board manufacturer's oxidation of the Shenjin circuit board is a contamination of the gold surface with impurities. The oxidation of the impurities attached to the gold surface causes oxidation of the gold surface, which is often referred to as oxidation. In fact, the theory of gold surface oxidation is not accurate, gold is an inert metal, under normal conditions will not oxidize, and attached to the surface of the impurities such as copper ions, nickel ions, microorganisms, etc. under normal circumstances are easily oxidized to form gold oxidation Things.
Third, through observation, it was found that the oxidation of the Shenjin circuit board mainly has the following features:
1. Improper operation results in contaminants adhering to the surface of the gold, for example: unclean gloves, fingertips touching the gold surface, gold plates and dirty surfaces, and contact with the backing plate; this kind of oxidation area is large and may appear at the same time. In the adjacent multiple pads, the appearance of lighter colors is easier to clean;
2. Semi-plugging holes, small-scale oxidation near the via hole; this kind of oxidation is due to the yao water in the via hole or half-plug hole is not cleaned or water vapor remains in the hole, and the yao water in the finished product storage phase slowly diffuses along the hole wall. The gold surface forms a dark brown oxide;
3. Poor water quality causes impurities in the water body to adsorb on the gold surface. For example, water washing after immersion gold, washing with a finished plate washer, such oxidizing area is small, usually occurs at the corners of individual pads, showing more obvious The water stains; after the gold plate has been washed, the pad will retain water droplets on the pad. If the water contains more impurities, the water droplets will rapidly evaporate and shrink to the corners when the plate temperature is high, and the impurities will solidify after the moisture evaporates completely. The main contaminants at the corners of the pad, after water immersion, and after washing with the finished plate washer are the micro-organisms. In particular, the tanks using DI water are more suitable for fungus breeding. The best test method is bare hand touch. The dead angle of the tank wall is to see if there is a smooth feeling; if there is, the water body has been polluted;
4. Analysing the customer return plate, it was found that the gold surface is less dense, the nickel surface is slightly corroded, and the oxidation site contains an abnormal element Cu. This copper element is likely to be caused by the poor density of gold and nickel, and the migration of copper ions. After such oxidation is removed, it will still grow and there is a risk of re-oxidation.