Failure analysis delamination

The acoustic microscopy s primary application to date has been for failure analysis in the multibillion-dollar microelectronics industry. The technique is especially sensitive to variations in the elastic properties of semiconductor materials, such as air gaps. SAM enables nondestructive internal inspection of plastic integrated-circuit (IC) packages, and, more recently, it has provided a tool for characterizing packaging processes such as die attachment and encapsulation. Even as ICs continue to shrink, their die size becomes larger because of added functionality in fact, devices measuring as much as 1 cm across are now common. And as die sizes increase, cracks and delaminations become more likely at the various interfaces. 

PMDA-ODA on Si02. It is clear from Fig. 3 that the adhesion of PMDA-ODA to SiO, surface is significantly improved by the application of APS. This is not only seen initially but also after exposure to extended times at T H conditions, i.e. the reliability of the interface has been improved. Notice the spontaneous delamination (zero peel strength) of the PMDA-ODA film from non-APS treated silica surface after only 100 h in T H. It should be pointed out here that the 100 h exposure was the first point at which the samples were removed from the T H test chamber. It is possible that the delamination may have occurred much earlier than the 100 h reported here. Table 2 shows the locus of failure analysis results for the interfaces after initial peel and after exposure to T H for 100 (no APS only) and 700 h. 

A future trend in composite bolted joint design is the use of more advanced continuum damage mechanics approaches to model joint failure, so that non-linear shear behaviour and gradual stiffness degradation can be implemented. An important element of joint failure is delamination, and many efforts are being undertaken to implement delamination in finite element models. However, for bolted joints analysis this poses many problems due to the large number of delamination interfaces in thick laminates. 

Analytical approaches for adhesively bonded structures are presented in this chapter. Stress analysis for adhesively bonded joints is conducted using the classical adhesive-beam model and the other adhesive-beam models. Closed-form solutions of symmetric joints are presented and analytical procedures of asymmetric and unbalanced joints are discussed. Load update for single lap joints is investigated in detail. Numerical results calculated using the classical and other formulations are illustrated and compared. It is shown that the nonlinear adhesive-beam model based on the Timoshenko beam theory provides enhanced results compared to the linear adhesive-beam model based on the Euler beam theory for adhesively bonded composite structures. Analytical solutions of energy release rates for cohesive failure and delamination are presented, and several failure criteria are reviewed and discussed. 

For laminates which are prone to open-mode delamination, progression of delamination as the applied load increases must be modeled first. In addition, the effect of delamination on ultimate strength must be estimated. This failure analysis is not an easy task. 

Applications of ISS to polymer analysis can provide some extremely useful and unique information that cannot be obtained by other means. This makes it extremely complementary to use ISS with other techniques, such as XPS and static SIMS. Some particularly important applications include the analysis of oxidation or degradation of polymers, adhesive failures, delaminations, silicone contamination, discolorations, and contamination by both organic or inorganic materials within the very outer layers of a sample. XPS and static SIMS are extremely comple-mentar when used in these studies, although these contaminants often are undetected by XPS and too complex because of interferences in SIMS. The concentration, and especially the thickness, of these thin surfiice layers has been found to have profound affects on adhesion. Besides problems in adhesion, ISS has proven very useful in studies related to printing operations, which are extremely sensitive to surface chemistry in the very outer layers. 

Other types of commercial coatings and membranes were also evaluated in the test facility at that time, and analysis indicated the performance of the sulfur composite was superior to all the others tested. At the conclusion of the test, all the other systems were in various stages of failure because of cracking, crazing, delamination, or tearing. 

Differential movement caused by cold to heat and wet to dry repetition, is the major cause of delamination, disbond or fall-off failures of tile covering finish which occur at the interface between layers made up of different materials in the exterior concrete walls. The authors executed numerical analysis with simplified models for simulation to examine what internal stress distribution is generated in the exterior wall and how the characteristics of each material affect the stress generated in the wall under cold to heat and wet to dry cycles. 

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