I am not sure what you are referring tohere as "Regular" lead free solder.
I have used piles of Eutectic 147 solder, which was a lead free solder developed for use on stainless tubing for the dairy industry. I can assure you it is not junk, & it definitly is not priced that way. Have also used Brownell's Force 44 with good results, also an expensive lead free solder. I don't know about all brands but the 95-5 solders I have used were also lead free, the 95 being tin & I seem to recall the 5 was cadmium. Most of these solders do require an acid flux & do not give good results with a resin flux. This requires a through clean-up & neutralizing but they give a very strong bond. For this purpose you might just use a good thin adhesive.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra