I have lots of Portenta H7s and all of them have ground through-holes that are so difficult to solder on. I remember facing similar issues with other devices also but can’t exactly tell you which ones right now.
Problem is that they often lose contact completely if I’m not too careful with connecting and disconnecting.
I wonder why this happens (something to do with charges on the metal contact?) and how to get over this stupid challenge.
Regards,
PC
GND pins can be difficult to solder because they are connected to a large ground plane on the PC which soaks up the heat
The solution may be to use a larger soldering iron tip an/or a slightly higher tip temperature
What type of solder and flux are you using ?
Thanks for replying!
I’m using a generic lead-free Sn 99.3 and Cu 0.7 solder. My flux is also a pretty generic paste suitable for lead-free solder material (here’s the SDS No Clean Flux Gel/Paste).
PC
Personally I prefer good old 60/40 tin/lead solder
What temperature have you got your iron set to ?
What does the specification of your solder say about temperature ?
430 deg C sounds way too high as, if nothing else, it will burn off the flux and reduce or eliminate its effect
I use 350 deg C with 60/40 flux cored solder and either liquid or paste flux of uncertain origin
Temperature of the board (and room temperature) can make a big difference.
Try to gently warm up the whole board with a hair drier before soldering.
Leo..
A temperature controlled soldering iron is best, lots of reserve power when you need it, without getting so hot it shortens the tip life.
My preference is 63/37 solder with multi core flux, a bit harder to find these days.
Your photos show that the quality of your soldering varies greatly from pin to pin, not especially for GND.
If you are not very good in soldering do not use a lead-free solder. And add more flux.
Hi @prithulc.
I don't think sharper will help. That is only beneficial in cases where you are doing soldering work where you need to apply heat to a small area precisely.
The problem with this conical tip shape is it makes it more difficult to get a lot of surface contact, thus limiting the amount of heat you can transfer. Try to position the tip so that a length of the side of the tip is in contact with the area being soldered, rather than only the tiny area of the point of the tip.
If you have access to a tip with the chisel shape, try that instead. This tip shape makes it much more easy to get a lot of surface contact:
+1
A finer/sharper tip has less mass, so cools down quicker.
The #1 mistake that beginners make is to put fresh solder on the tip.
That burns off the flux too fast. A band-aid is to use (more) flux.
Add solder to the joint while heating up the joint. Don't push the solder on the tip.
Soldering with 63/37 mildly activated rosin-core solder (RMA) does not need messy added flux and cleaning afterwards. Beginners shoulds stay away from lead-free.
Leo..
Thank you for your inputs, @UKHeliBob @Wawa @david_2018 @b707 @ptillisch !
I have placed an order for a lead solder and a chisel tip, which I hope helps. I’m having a better experience when I apply flux as I go and skip fresh solder on tip
Regards,
PC
That depends on why you are doing it. If it is to tin the tip so that it has a thin layer of solder on it then that is OK. However, if you are trying to add solder to the tip to carry it to the joint then that is wrong
What I do is to wipe the hot tip on a damp sponge and/or brass wool to remove any detritus, tin the tip with a small amount of solder, put the tip on the joint to warm it up, feed in solder to make the joint, stop feeding in the solder and remove the tip from the joint to allow it to cool down
You don't need to take all the steps above when soldering a series of joints such as adding a line of pins to a board as you do not need to clean the tip between soldering each pin
In my mind the most important thing to do is to make sure that what you are soldering is clean before you start. Sometimes I use flux but often not
I find that making nice solder joints is very satisfying when you do it right
Interestingly
Is it means that you often solder without flux at all? How is this possible?
It means that sometimes I don't add extra flux and depend on the flux cored 60/40 solder to provide enough.
If soldering a joint of any kind proves difficult without extra flux then I clean the tip and add extra flux as a matter of course
So I understand...
The question is emerged because I don't like using a flux cored solder and prefer to add a flux separate
My method for soldering a row of pins to the board.
I generously coat all the pins and connections with flux. I use a lightweight, non-aggressive rosin-based flux that's easy to wash off, so I don't worry about it staining the board. Flux is needed not only for chemical surface treatment but also for heat transfer from the soldering iron to the component, so it's important to use plenty of it.
Next, solder each pin in turn, heating the joint and applying flux-free solder wire.
After soldering all the pins, I re-coat all the connections with flux and go over the entire row again. I apply the soldering iron to the pin and heat the joint until it's completely melted. This forms a nice cone of solder around the pin, removes any drips, and evens out the solder between adjacent pins.
Why is that ?
i don't think the quality of the soldering looks too bad. The highlighted pin is a bit of a mess.
The object of soldering to through plated holes is to get the section of the pin in the hole thoroughly making contact. Any excess solder above the board can help to strengthen the pin.
I often find that the flux cores in cored solder aren't enough on their own and additional flux is required.
Chipquik do a range of fluxes that work well. I use one of the syringe applied types.
Soldering is allabout getting a lot of things right, Temperature, decent tip, cleanliness.
A low temperature solder with silver added can help.
Going over a row of pins with solder wick braid can clean and tidy things up.
Again, I add flux to the wick to get a good flow.
The only time I don't use cored solder is when soldering capillary copper water pipe, but that's another story.
Electronics solder is a hollow wire, filled with flux.
Rosin core flux has natural tree rosin in that core.
Multicore rosin flux has up to five tubes in the solder wire, filled with rosin.
If you can't solder without adding flux, then you can't solder.
Leo..
