Identification of imperfections
Much confusion has existed in the industry regarding the identification of defects that exist in laminates. To help Identify those conditions, refer to the following sections where definitions, illustrations, and photographs have which precisely define and identify the following conditions:
It is important to note that laminate defect conditions may exist when the fabricator receives the material from the laminator, or may become apparent during the fabrication of the printed board. Some defects may be induced during processing.
The use of acceptability criteria
Everyone cannot be an expert of laminate defects. some non-destructive visual criteria must be established to aid in marking a decision regarding acceptability levels.
A surface condition of base material in which the unbroken fibers of woven glass cloth are
not completely covered by resin.
Weave exposure is acceptable for classes 1 and 2, provided the conductor spacing is not
below the minimum .
Weave exposure is not acceptable for class 3.
A surface condition of base material in which a weave pattern of glass cloth is apparent
Although the unbroken fibers of weave cloth are completely covered with resin.
Weave texture is an acceptable condition in all classes but is sometimes confused with
Weave with weave exposure because of similar appearances.
This example could be either weave exposure or weave texture .
The difference cannot be determined from this view.
The difference can be discerned using non-destructive tests or microsection.