Substrate-attach adhesives properties

Table 5.2 Properties of some die- and substrate-attach adhesives... 

Table 5.2. Properties of Some Die- and Substrate-Attach Adhesives... 

A variety of substrate- and cell-attached factors influence neural development by regulating adhesion properties of cells (see Ch. 7). Interactions occur directly between cells or between a cell and the extracellular matrix (see Ch. 2). The molecules mediating these interactions have been implicated in regulating the specificity and timing of cell-cell adhesion and the consequences on cell morphology and physiology. Hence, they influence the ability of cells not only to migrate but to sort themselves out and to stabilize spatial relationships considered important for the process of differentiation. 

Note that there are closed-cell and open-cell foams. Adhesives may spread or wick deeply into the open-cell variety, thereby affecting the resulting mechanical properties of the foam and perhaps even weakening the foam. When foam is bonded to another less porous substrate, the adhesive could be applied to the nonfoam substrate to minimize the wicking and ingress of the adhesive into the body of the foam. With the closed-cell variety, the adhesive cannot wick deeply into the foam, but usually the foam s skin must be machined or abraded to allow for some surface roughness for the adhesive to mechanically attach. 

Properties of some film adhesives for die attachment and for substrate attachment are given in Tables 3.16 and 3.17. 

Table 3.17 Typical properties of some film adhesives for substrate attachment...

A wide variety of films and properties is available. Eap-shear aluminum-to-aluminum bond strengths range from 1,000 psi to over 3,000 psi and electrical properties are similar to those for the paste versions. Properties of film adhesives for die attachment and for substrate attachment are tabulated in Tables 3.16 and 3.17. 

Table 3.17. Properties of Film Adhesives for Substrate Attachment... 

Adhesives are used extensively in nature. Their diversity is a source of inspiration for developing new man-made adhesives different from those currently available. Bioadhesives exhibit a certain number of characteristics that make them differ greatly from artificial adhesives sensitivity to - and critical dependence on - the presence of humidity, recurrent use of molecular constituents, ability to form sound attachments with a wide diversity of substrates, variation in properties in response to performance requirements, improved fatigue resistance and resilience, and conferring to the biological hybrid materials a damage-tolerant design. 

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