Question: If we are using a solder pot to tin wires and create solder joints (splices), what Maximum Limits of Solder Bath Contaminant do we adhere to (IPC J-STD-001, table 3-1)? Preconditioning or Assembly? What exactly does Preconditioning mean in this context?
Answer: The solder limits to be followed are from 001 as you stated and those are in table 3-1.
What does preconditioning mean? With the industry change from Tin/Lead solders to Lead-Free solders, some components are going to have to changed over. For examples component coming in with Lead-free coating and need to be tin/lead coated, this is a preconditioning element, and the same applied if the tin plated components have to be changed to SAC or other lead-free alloy. This is typically the third column in the table.
Assembly means being used for soldering the components to the board itself, be it either manual soldering or mass soldering.