The key characteristics of adhesives include rheological properties (viscosity, thixotropy, anti-sagging property, stringing property, storage period/conditions, and service life) and mechanical properties (adhesiveness, mechanical strength, heat resistance, curing cycle, electrical stability, etc.).
(1) When selecting adhesives, first ensure they meet environmental requirements, and then comprehensively consider three aspects of the adhesive's performance: pre-curing properties, curing properties, and post-curing properties.
(2) Since two-component adhesives need to be mixed in appropriate proportions within a proper time, which increases process difficulty, priority should be given to one-component systems.
(3) Prefer colored adhesives that are easy to distinguish from solder mask and circuit board materials, as this allows for quick identification of issues such as missing components, adhesive quantity, contaminated pads/components, and voids, facilitating process control. Common adhesive colors include red, white, and yellow.
(4) Adhesives should have sufficient adhesiveness to ensure secure bonding between components and circuit boards before curing. Both usually increase with viscosity; highly adhesive materials can prevent components from moving during circuit board mounting and transportation.