- An image of the product I'm working on. The image depicts pins -Vo,+Vo,-Vin,+Vin- these four pins are the troublemakers.
- A sample image of the product as it was soldered in the past. As you can see, while past employees do not remember running into the trouble I'm dealing with, the solder joints do look poor at a glance.
- A specification sheet I received when communicating with the manufacturer about wave soldering.
Problem: I am soldering wires to a DC-DC converter that is intended to be wave soldered onto a PCB. Soldering wires directly to it is how it was done in the past and I do not have PCBs readily available or a wave soldering machine. There are nine pins- the five "center" pins are thin, run of the mill terminals that solder easily sticks to. There are four voltage carrying pins (-Vo,+Vo,-Vin,+Vin) that are thicker. According to the specification sheet (image 3) they are 3.5mm non plated through hole pins. Solder will not stick to these troublemakers. Solder does notwet or flow but instead balls up.
Using my "regular" soldering iron operates between 50F and 104F (not sure which mine is set to; Im new here.) Using my regular, I cannot get solder to stick at all. Using a Weller with a variable temperature set to maximum (850F,) I am able to get the solder to stick somewhat, but the solder joints are poor, with poor connections and at least one came off. Re-soldering the joints with more patience (heating the pin for much longer) and liquid flux, I was able to get a firmer, cleaner looking solder joint. I suspect the solder isn't really sticking to the pin, but instead is flowing around it like a donut. Also, the pin looks worn; the heat is likely damaging it.
Do you have any instruction on how to solder non-plated pins?