Rework Stripping

All physical things, the stars and the universe are mathematically related. 

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Organic versus Inorganic Bottom Anti reflection Coating and Rework/Stripping Issues... 

If a part fails inspection because of a bad finish, it is usually reworked by stripping off the paint and returning it to the cleaning operation. 

Figure II. C Is ESCA spectra for three reworked wafers. Note that the best results are observed for the acetone stripped wafer in the sense that it is ready to be recoated without silane reprinting.

Two possible outcomes exist for a wafer that fails the measurement-and-inspection step. If the wafer has a problem from a previous operation that makes it unacceptable, then it is scrapped. If, however, the problem is associated specifically with the quality of the pattern in the resist film, then the wafer is reworked, which involves essentially stripping off the resist and organic antireflection coatings. Following reworking, such a wafer is reinserted into the lithography process line. 

In addition to the above, another very important factor in the pollution potential from coloration processes is the percent of right first-time dyeings. Corrective measures such as reworks (e.g., redye, stripping) and shade adjustments (e.g., top-ups, adds) are very chemically intensive and have a much lower expectation of success than the first-time dyeing. Every situation is different, but typically batch dyeing operations with 5% or less reworks are considered good. Reworks over 10% are in most cases clearly excessive [3]. 

Because the developer also attacks the exposed dielectric laterally, sloped-wall vias are produced. Consequently, metallization of these vias entail a metal deposition technique that fully covers the sloped wall. In addition, vias in the adjacent layers must be staggered, which decreases the interconnect density. Besides being a simple process, ease of reworking is another advantage of the utilization of a photosensitive polymer dielectric. Being able to easily remove the xmwanted dielectric layer before hard baking avoids the stripping process. 

It is very important to have an inspection step immediately after development to check for registration, mask in holes, feature resolution, dam retention, lifting, and so on. Once the panels have been cured, it is significantly more difficult to strip and rework the solder mask, and the rework process is more likely to cause the panels to be scrapped. 

Stripping is the removal of thick deposits on a surface. For example, stripping is used to remove thick oxide layers by pickling and to rework coated substrates, as well to clean fixtures and removable vacuum surfaces. Table 3.11 fists a number of stripping chemicals for removing deposits from substrates, fixtures, and other surfaces. 

Rework To take a part that has been rejected in inspection and repair or redo it to overcome the reason for the rejection. May include stripping of a coating. 

The solder is usually applied to the joint in the form of wire or strip that can be touched against the joint when it is sufficiently hot snch that the solder instantly melts and rnns into the gap. Alternatively, the solder may be applied as small cnt pieces of thin sheet (known as paillons) by placing them over the joint seam or occasionally in the gap prior to heating. Preferably, gold solder paste is used and has a number of advantages in terms of faster prodnction, lower skills necessary, no necessity for the separate application of flux, less rework and cleaning up post soldering, fewer defects, and reduced costs [48,49]. 

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