I. What factors influence the curing time of resin adhesives?

(1) It is crucial to mix the resin adhesive compound according to the supplier's recommended formulation ratios. For cold-embedding resin series, increasing the volume of resin powder can shorten curing time. For crystal resin series, thoroughly mixing the accelerator and resin is essential first; then, appropriately increasing the volume content of the curing agent can reduce curing time.

　　(2) Appropriately raising the ambient temperature can shorten curing time, making baking a conventional method for this purpose.

　　II. Does increasing the amount of curing agent or resin powder directly accelerate curing? No! Excessive amounts of either will increase the viscosity of the resin mixture. Excessively high viscosity can cause incomplete embedding of micro-pores, directly compromising the precision of subsequent specimen grinding.

　　III. What other precautions prevent incomplete embedding of micro-pores? After thoroughly mixing the resin, pour it into the mold from one side of the specimen to expel all air trapped within pores or voids. Avoid pouring resin directly from above the specimen, as this may cause trapped air to form incomplete embedments.

　　IV. Why is polishing required for metallographic sections of circuit boards? During grinding, the sections undergo deformation due to the cutting force of abrasives. Fine grinding removes deformation caused by coarse grinding, while polishing primarily eliminates deformation from the fine grinding process. However, if the sectioned sample is not used for quantitative analysis, the polishing step may be omitted.

　　5. How to distinguish the thickness of different metal layers in a metallographic section of a circuit board? After polishing the specimen, etch it with a metallographic micro-etching solution for 5–10 seconds. Under a magnifying glass, the thickness of each metal layer becomes clearly visible.

　　VI. Is longer polishing always better for sectioned specimens? No! Typically, 5–10 seconds of polishing suffices. Excessive polishing time may cause darkening along the specimen edges. Note that during polishing, each direction should be polished uniformly in sequence to eliminate residual deformation from fine grinding in all directions.

　　VII. How should over-polished metallographic sections be restored? Simply re-polish after 5–10 seconds of fine grinding.

VIII. How should grinding speed be controlled during metallographic section preparation? Avoid excessive speed, as higher speeds increase cutting force per unit area, causing greater sample deformation. This reduces the ability to correct deformation during subsequent fine grinding and polishing.

　　9. How should water flow on the grinding machine be controlled during circuit board metallographic section grinding? Maintain a relatively high water flow rate throughout grinding to dissipate heat generated during the process and promptly remove grinding debris. This minimizes deformation and prevents residual particles from adhering to the specimen surface.