Although I’ve seen many companies who have switched to lead-free soldering in their wave solder machines, I’ve not seen any internal comparative analysis results from these operations.

This phenomenon of comparative analysis used to be a common occurrence during the Tin/Lead soldering operations however I would imagine that with the various patented alloys today, the comparison is not so much evaluating the differences between suppliers but understanding the differences between the alloys.

Since many of the lead-free alloys are patented, one would have to contact the vendors or suppliers directly to get any information about their particular alloy combinations and operational profiles.

As for which of the alloys is most widely used, IPC and iNEMI have recommended the use of SAC 305 alloy, while the Japanese manufacturers are recommending the use of Sn100C solder. They both work fine, but users have to do the reliability work to determine which is best for their process and products. Hence, experiments are still being conducted and the results are still being developed to create an overall industrial application of these alloys.

At this time, the solder with increasing market share in wave applications is tin-nickel-copper, such as SN100C from Nihon Superior. I don’t know if there is any published data on which lead-free solder is the most widely used.

There is not any testing that I am aware of comparing brands of lead free solder. However there are a lot of test comparing alloys. The first lead free wave solder used was SAC305 however there is a trend to move away from high silver alloys to no silver of low silver alloys.

There are several conditions that need to be prioritized, copper dissolution rates, appearance ( grain structure), wetting, voiding, and maximum temperature requirements. All of these come into play to choose a lead free alloy. The largest move has been to Sn/Cu + alloys. Additives (+) can be Ni, Co, Bi, Ag to mention the most popular additives.

I have my favorites as do most of the people responding to your question.

Can't help with the solder bar issue but Lead Free Intrusive Reflow is a process which eliminates the need for wave soldering. I can email you a copy of a recent article presented at APEX 2007 on this subject.