ABSTRACT
The following sections illustrate some of the defects that can arise from contamination at the laminate level. They are divided into two general defect groups: externally observable and internally observable. Externally observable defects are defined in the IPC-A-600 standard titled Acceptability of Printed Boards as “those features or imperfections, which can be seen and evaluated on or from the exterior surface of the board. In some cases, such as voids or blisters, the actual condition is an internal phenomenon and is detectable from the exterior.” The standard defines internally observable defects as “those features that required microsectioning of the specimen or other forms of conditioning for detection and evaluation. In some cases, these features may be visible from the exterior and require micro-sectioning in order to assess acceptability requirements [72].” Both groups are discussed in this section with figures illustrating identification of the defect externally and internally.
