Ink Marking and Laser Marking Failures

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Marking Failures

Marking Failures refer to the various ways in which the marking on a device package fails to meet its required visual/physical and chemical specifications. The more commonly encountered marking failure attributes encountered in the industry are presented below.

The ability of a package to be marked in accordance with applicable specifications is known as 'markability.' Poor markability is the condition wherein the package is difficult or impossible to mark correctly and/or the mark on the package exhibits insufficient permanence. Ink markability problems are often due to the inability of the ink to adhere to the surface of the package. Laser markability problems are often due to improper branding equipment set-up, but may sometimes be due to textural problems on the surface of the package as well.

Poor adhesion of ink marks or brands on the package is usually caused by the presence of a thin film or layer of contaminants or foreign material on the package surface. For instance, packages with excessive amounts of mold release agent on their surfaces are likely to exhibit poor markability. It may also be due to the use of an incorrect, incompatible, or expired ink.

Common marking failure attributes which are applicable to both ink and laser marking include the following: 1) missing mark, wherein the entire mark is absent from the package; 2) incomplete mark or missing character, wherein only a part of the mark is absent from the package; 3) misoriented mark, wherein a mark appears in incorrect orientation with respect to the package; 4) misplaced mark, wherein a mark is in incorrect location with respect to the package; 5) wrong format, wherein a mark has a different style or character arrangement than what is prescribed; and 6) poor mark contrast.

The term 'illegible mark' is also widely used in the semiconductor industry, but this term can often be described more specifically as either an incomplete mark or as a mark with poor contrast.

Mark permanency failure, or the failure of a package to retain the quality of its ink mark over a prescribed period of time, is also a critical failure attribute of the ink marking process. The mark permanency test (MPT), which is described by Mil-Std-883 Method 2015, is performed to test the mark permanency of a sample. The MPT subjects the package marking to a set of chemicals which, under normal circumstances, should not be able to erase the mark or a part thereof.

Poor laser markability is usually caused by incorrect laser branding settings. Packages with textural problems or defects may likewise exhibit poor contrast after laser marking. For example, reworked packages that have undergone sand blasting generally exhibit marks with poor legibility.

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