Surface-mount adhesives characteristics

The adhesion characteristics of these two groups of substances were considered by Rumpf [262]. In the case of particles that are not temperature sensitive, the force of adhesion will predominate over the elastic detaching force when the velocity is low (Fig. IX.S.b). As the flow velocity increases, particle rebound is possible. The rebound of spherical glass particles with diameters up to 30 /im from a steel surface mounted perpendicular to the dusty stream is observed at a flow velocity of about 13 m/sec. 

In the surface mount assembly process, type 11 and type III boards will always require adhesive to mount the SMDs for passage through the solder wave. This is apparent when one envisions components on the bottom side of the substrate with no through hole leads to hold them in place. Adhesives will stay in place after the soldering process and throughout the fife of the substrate and the product, since there is no convenient means for adhesive removal once the solder process is complete. Additionally, adhesives can be used to enhance both thermal and electrical conduction between device features and board features. This means use of an adhesive must consider a number of both physical and chemical characteristics ... 

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