The issue is how to best secure stranded wire to a terminal, not how to secure the terminal to the PCB. Soldering is obviously preferred for the latter case, but when dealing with stranded wire, a good crimp is actually better than a good soldered connection. Done properly, the crimp forms a cold weld that's as close to a perfect connection as you can make.
Soldering can work well too, but there are so many things that can go wrong. Heat can deform the connector housing, lowering the contact pressure. Solder might run down the connector and coat the contact surface, making it unreliable over time. It might also wick down into the insulated portion of the wire, turning what should be a flexible part of the interconnect into a reliability problem, especially in the presence of motion or vibration. Last but not least, lead-free solder complicates visual inspection, making it harder to reject bad connections at the factory.
You can make bad connections with either soldering or crimping, but all in all, crimping usually wins when it comes to cable assembly. In a production setting, it is easier to establish and enforce a high-quality process when all you need is the right crimping tool and die and a few minutes' training.
" Last but not least, lead-free solder complicates visual inspection, making it harder to reject bad connections at the factory."
I x-ray every soldering job out of the oven and off the irons where I work, and that's a TINY LED company. Visual inspections of solder joints can be very unreliable no matter which solder is used. A company making these sorts of cables should be using even a cheap $10K Scienscope at the minimum.
Soldering can work well too, but there are so many things that can go wrong. Heat can deform the connector housing, lowering the contact pressure. Solder might run down the connector and coat the contact surface, making it unreliable over time. It might also wick down into the insulated portion of the wire, turning what should be a flexible part of the interconnect into a reliability problem, especially in the presence of motion or vibration. Last but not least, lead-free solder complicates visual inspection, making it harder to reject bad connections at the factory.
You can make bad connections with either soldering or crimping, but all in all, crimping usually wins when it comes to cable assembly. In a production setting, it is easier to establish and enforce a high-quality process when all you need is the right crimping tool and die and a few minutes' training.