Metal-polymer adhesion

The primary challenge facing adhesive bonding of metals is to obtain sufficient durability of a bonded structure. Initial bond strength in metal-polymer adhesive joints is almost invariably excellent. Challenging the application of adhesives in polymer-polymer joining, however, is the problem of obtaining a joint that is... 

The predominant applications of present day metal/polymer adhesion technology are for the development of strong metal-to-metal structural adhesive joints and durable protective coatings. 

This review will first present the metal/epoxy resin adhesive system and discuss how the presence of metal oxides influences adhesion secondly, present the reasons why these systems exhibit very good adhesion strength under dry conditions and why this adhesion strength is greatly reduced in the presence of water thirdly, examine possible methods of increasing their durability in wet environments and finally, discuss some of the spectroscopic techniques that are currently being used to aid in the advancement of metal/polymer adhesion technology. 

Metal/Polymer Adhesion System 2.1 Metal Surface... 

Figure 3 241 illustrates that the durability of metal/polymer adhesion systems can greatly be influenced by the metal pretreatment chosen 1 K Therefore, it is very important to select the best pretreatment for a given system. 

All adhesion scientists will agree that water is a very destructive environment for metal/polymer adhesion systems (see Fig. 5). Since water is one of the most commoi environments encountered, the effectiveness of metal/polymer coating and structural bonding systems has been severely limited by this great loss of adhesion strength in the presence of water. 

In the past, the detrimental effect of internal stresses on adhesion strength has often been ignored. Conversely, in a few cases, the presence of internal stresses has been proposed as the primary reason for adhesive failure96 "-104-108) authors believe that internal stresses can play an important role in reducing the adhesion strength of metal/epoxy systems and that the theories developed by Croll 96 102) and Shimbo et al.99) should lead to an increased awareness of this fact. In addition, further work must be completed in this area so that the usefulness of these theories and the effect of internal stresses on metal/polymer adhesion systems can be successfully analyzed. 

In Section 4.2, the strength loss mechanisms of metal/polymer adhesion systems in the presence of water were discussed. From this discussion it is evident that high initial adhesion strength is not the only important property of these systems. Actually, if a metal/polymer adhesion system is exposed to humid environments, it is more important for the system to exhibit good durability. 

Over the past fifteen years a number of different approaches have been taken in an attempt to increase the durability of the metal/polymer interfacial region in the presence of water. These attempts have met with varied degrees of success. However, to date adhesion scientists are still searching for a means of achieving sufficient wet environment durability, so that the enormous potential of metal/polymer adhesion systems can soon be utilized effectively. The authors have selected to discuss a few of the more promising durability-enhancing methods. 

Recently, many research efforts have been directed at developing pretreatments for metal surfaces which produce oxide layers with pores, fibrous projections, or microscopic roughness which can enhance metal/polymer adhesion by mechanical means. In order for the pretreatments to lead to an increase in durability, the oxide layers formed must be stable under environmental conditions. The bulk 3l-33 S2-128> of the research in this area has been completed in an attempt to increase the durability of... 

Additional work must be completed before these hydration inhibitor treatments will be widely used. However, it appears that combined FPL/inhibitor pretreatments have the potential of producing water stable aluminum oxides with structures that promote mechanical aspects of adhesion in a relatively simple manner. Since mechanical adhesion mechanisms are not greatly affected by water, these pretreatments show promise as a means of increasing the durability of metal/polymer adhesion systems in wet environments. 

Therefore, relieving internal stresses that are present in polymer adhesives and coatings should result in an increase in the strength of metal/polymer adhesion systems150. ... 

Ion beams are often utilized to prepare clean surfaces for PES studies or for depth profiling through a sample. This causes problems in polymer studies as the surface can be chemically degraded as has been demonstrated in the case of polyimide (19,20). This effect, however, has been used to increase metal/polymer adhesion, while the exact mechanism (chemical, mechanical) for the improved adhesion for the metals to polyimide is not yet completely understood (21,22). 

Metal-polymer adhesion has been of interest in recent years for the electronic packaging technology. A wide range of studies has been devoted to the understanding of interactions between metals and polymers, mostly on polyimide (1-3). 

Supercritical carbon dioxide has recently begun to be studied as a substitute for chlorofluorocarbons (CFCs) as a cleaning solvent for industrial processes. Common materials of construction in industry encompasses all of the familiar materials including ceramic, glasses, metals, polymers, adhesives, etc. Of these materials, it is anticipated... 

Metal/Polymer Adhesion Effect of Ion Bombardment on Polymer Interfacial Reactivity... 

The outer portions of the underside of the metal trace become bronze colored. As the bond formation interaction progresses across the entire metal strip, a uniform bronze hue is achieved. In region B the metal/polymer adhesion is developed completely and no deleterious effects are observed. During this stage, adhesion at the metal lymer interface is predominately due to oxygen-aided chemical bonding between copper and polyetherimide l A Finally, in region C, overoxidation or thermal destruction of the chemical portion of the... 

In electronic packaging technology, metal-polymer adhesion has been important for some years. Many studies have been devoted to the in-... 

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