ELECTROPOLISHING

Optimum printing result with surface polish

In addition to nano-finishing, Photocad also offers SMT stencil electropolishing. The micro-roughness of the stencil surface is therefore significantly reduced, the opening walls are smoothed and the finest ridges are removed.

A surface coating gives you the best results for solder paste printing and circuit board assembly.

ELECTROPOLISHING OF SMT STENCILS

Photocad is the only manufacturer in Germany to have an automatic system for SMT stencil electrochemical surface processing.

The laser cutting of SMT stencils produces melt residue on the inner walls of the openings, which can affect the quality of the printing result.

Electrochemical polishing and deburring (electro-polishing) improves a number of metallic surface properties in one operation. The micro-roughness of the template surface is significantly reduced. The opening walls are smoothed and the finest ridges removed.

For particularly delicate applications, standard surface treatment (double-sided brushing) is not sufficient. In this case, a surface treatment by electro-polishing and/or nano-coating is recommended.

Electropolishing machine

THE PROCESS

The principle of electropolishing is a reversal of the galvanic process: whereby metal ions undergo addition on to a workpiece.

Phase 1
The SMT stencil is lapped by an electrolyte solution and positively charged so that it acts as an anode (positive pole). The cathode (negative pole) moves in the electrolyte over the stencil.

Phase 2
When direct current is applied, the metal ions are removed from the anodic stencil and move towards the cathode.

Result
Thus, the entire surface – especially the laser-cut inner walls – becomes smoothed and delicately deburred.

ADVANTAGES OF ELECTROPOLISHING

  • Using electropolishing elicits a significant improvement in printing, particularly for very small pad apertures, as solder paste is distributed better thanks to the smoothed walls
  • Electropolishing only works on a microscopic scale, and does not change the shape or macrostructure of the component. The component, in this case the SMT stencil, is not subjected to any mechanical or thermal stress
  • The stencil is easier to clean
  • The results can be reproduced with a higher level of accuracy

LATEST TECHNOLOGY

Photocad is the only manufacturer in Germany to use the Poligrat EP110, L250-25 automatic electro-polishing system for the electro-chemical surface treatment of SMT stencils.

The system specially developed by Poligrat for Photocad ensures that the polishing process takes place in a closed chamber, controlled by a Siemens CNC control system. Work safety is significantly improved compared with conventional electro-polishing by hand. In addition, the automation guarantees consistently high quality.

In addition to electropolishing, Photocad offers surface nano-coating. For an optimal solder paste printing result with high requirement specifications, we recommend combining both surface finishing processes – electropolishing and nano-finishing.

FAQ

Do you recommend one electropolishing for all SMT stencils?

This type of surface requirement is particularly suitable for delicate application and the smallest components. Therefore, we offer SMD stencil electro-polishing in the ADVANCED and PERFORMANCE product lines.

Which type of refinement is more suitable?

For simple applications, standard surface treatment (double-sided brushing) is sufficient. The process of electro-polishing is used in delicate structures. The most exacting requirements additionally require nano-refinement. To overview