Which series filler medals are considered more economical due to their lower silver constant?

The series of filler metals that are deemed more economical due to their lower silver content is BCuP. This classification of filler metals includes copper-phosphorus alloys, which offer a lower cost alternative while still providing good strength and corrosion resistance. The reduced silver content directly contributes to their cost-effectiveness, making them a popular choice in applications where budget considerations are vital, without significantly sacrificing performance.

Filler metals like CuSn and AgCu contain higher precious metal content, making them more expensive. ZnAl, on the other hand, represents a different category of filler materials altogether and is not primarily focused on the silver content, making it less relevant to the question regarding economic considerations based on silver. Thus, BCuP stands out as the most economical option among the choices provided.