Wave soldering (ok not quite general SMT)

Started by phonoplug, June 17, 2022, 11:34:37 PM

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I've got a bench-top wave machine and its been a god-send when needed, but I don't use it that often. I was wondering if there are any more regular users of such things out there that could offer some advice about how to reduce bridging between pins. I don't often have the volume of stuff (or the time to experiment when I do sadly) to experiment. I can adjust the speed over the wave, pre-heat time, solder temperature wave height and so on. I've tweaked a couple of things but doesn't seem to have had a noticeable effect either way. I accept its unlikely there is a silver bullet to make them all come out perfect all the time. Should I just accept it does the level of bridging that it does and move on?


Hi. How much bridging do you get?

What temperature is the solder heated to? I have an old solermatic and it's dialed in pretty well. The solder bath is set around 265c but it moves around depending on style of use on the day and can rise above 270C.

I have an IDC connector on a board that caused some issues. I changed orientation by 90 degrees but also changed flux. I still get odd bridging but it's minimal. 

Order code. BLT FLUX 35-92-35. Comes in 5 litre containers. I have found it to give good results.

Speed is set to expose each joint over bath for about 4 seconds. Panel pre heat temperature is set to reach the panel to approx. 90C before it goes over the bath.


I also double checked the temperature of the solder bath using a probe like this.



Ah thanks for the replies, just seen them!

ok wow so you are at 265oC. I'm set to 245oC simply because that was what it was set to when I got it so I had nothing else to go by. I know the solder alloy its got in it melts at 222oC - how does that compare with you?

I use foaming flux that I get from Grove, seems to foam up and coat the board ok. Annoyingly the machine has a huge tank for flux which you have pretty much fill for the foam to be at the right height. Takes about 6-7L.

Speed over the wave you mention is probably fairly similar to what I'm set to. Preheat is just a timed thing so I don't really know what temperature it will be getting to - sits over the heater for perhaps 10 seconds before heading back up over the wave.

If your alloy is melting at a similar temperature to mine then perhaps I should up the temperature a bit for a first test. Its not bridging all pins that are close to each other but there are bridges on all panels in a few places, particularly where there are 0.1" pitch pins. Maybe thats just as good as it gets and I'm expecting a bit too much. Next time I do some panels on it I'll take a couple of photos.


I assume all solder metls the same unless its special stuff. Mine I believe is standard solder bar.

I have a foaming fluxer on my machine too. I think the flux compartment holds maybe a couple of litres. I always empty it back into the container after I use it though as the tank is open to the air.

I believe preheat you want to see your board heat to around 80 - 100C. Using a cheap IR gun, you can measure the temperature. I do not think its super critical but mine takes about 40seconds over the hot plate to heate up to temperature. I have varied this between 30 and 60 seconds and I am not how much difference it makes. The important thing is to not burn the flux else it will be no good by the time it gets to the solder bath.

I believe I read that the lower the temperature you can get away with the better but my 80kg solder tank is correct at 265 - 270. I am not sure about sures. I am using unleaded solder.

Some images would be good.



Hi, I have a Soldermatic too, it is a  Model 96/800 I bought new in 1998 and its still going well, my solder temp is set to 260 and I am using SN100C Lead free solder, I have added additional germanium to the solder bath to reduce the dross.
The Flux is foaming and is  labelled as 390-RX-HT and is thinned down with isopropanol.
I have tried many different water based fluxes as it would be a lot safer but I haven't  found one that works well enough, they also allow mould growth if the flux isn't used up quickly enough.
I don't drain the flux tank when I close it down I have made a silicon cover that fits over the bath when not in use this reduces the evaporation of the isopropanol.
the conveyor speed is set to a leisurely 0.75m/min the preheat is 290 deg C and the boards are preheated for 40 seconds, I suspect I could reduce the preheat time and temp but it works and I rarely have a bridging problem.
When it was originally commissioned the machine used leaded solder and the bath was set around 240 degrees.