Electronics > Beginners
Solder Paste Recommendations.
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nanofrog:

--- Quote from: wade7575 on September 20, 2018, 02:48:31 am ---...[snip]...it's when you get into the smallest SMD resistors on the market I can't solder with an iron no matter how hard I try and I have gotten a few kit's like that and was not able to build them.
--- End quote ---
I'm not sure how you're trying to do this, but the basic methodology will work with any size passive.
* Tin one of the pads.
* Flux the newly tinned pad as well as the un-tinned pad (one tinned, one not is based on new PCB).
* Place the part with tweezers with one hand, and hold the part in place. Now touch the tinned pad & part with the iron to tack that end to the pad.
* Solder the other side, then come back, add some additional flux to the tacked side, and finish soldering it.Sounds more complicated than it is, as it's actually quite quick and easy. Tip selection is important as well, which I'll address below.

Do note that with SMD, additional flux is a necessity as you'll find that contained within the solder wire's core just isn't enough. And this issue becomes more pronounced the smaller you go.


--- Quote from: wade7575 on September 20, 2018, 02:48:31 am ---The problem I have came into with the smallest SMD resistors on the market is that they did not leave any room for you to touch the iron to the pad no matter what size tip you use,I'm going to get some practice boards and just get good at setting the air flow and writing down what I find works good for not blowing the part's away,I have also watched a lot of SMD video's and understand not to just hold the heat on the device you want soldered you need to move the hand peace around and also preheat the that section of the board a bit as well.
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As mentioned, tip selection is very important, so what are you using?

Generally speaking, chisels or hoof/bevel shapes will do best (size the tip to the pad). Conicals tend to suck for most anything. The one exception would be a fine bent conical (these are good for the very smallest of passives IME).

I'd recommend taking the time to go over Hakko's Tip Selection page as it covers what types of jobs/situations the various tip shapes are meant for.  ;)


--- Quote from: wade7575 on September 20, 2018, 02:48:31 am ---...[snip]...IPA won't touch by just rubbing it off.
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All the alcohol does is get it to a liquefied state so you can absorb/blot it off using consumables such as Kimwipes, Q-tips (preferably something non-shedding), foam swabs, ... For really heavy deposits, use a brush and rinse as much off as you can with alcohol first. But you'll still have to mop the rest off.
wade7575:
I have been using a product called Krud Kutter that you can get a Home Depot Canadian Tire and Walmart,you can get it in a 1 gallon jug at Home Depot.

I have been using it for removing rosin flux and Amtech flux from my boards,it's not nasty in anyway shape or form and it works really good.

I just mix it at about 25 to 30% with water and soak the board in the mixture and let it sit for an hour or so,I have only started using the Amtech stuff and it went white and soft and I was able to brush it off easily with a Medium or Hard tooth brush.

I have never had Krud Kutter damage anything and your solder joint's will look as shiny as the day they were soldered after being soaked in Krud Kutter and water and even if you use just Krud Kutter not mixed with anything and put it on pure your solder joints years later will still be shiny,it's not one of those deals where it works great but you signs of stuff you don't want to see much later on.

The only thing I wouldn't do is soak a board with any moving parts on it and solder those parts on last after the board has been soaked and then clean those joints with pure Krud Kutter and let it sit for 10 or 15 minutes then brush it and rinse it.The reason I say not to soak a board with moving parts is because I did a Velleman shake dice kit that has a switch with a ball that rattles back and forth to turn the dice on and a bit of the rosin that was in the water and Krud Kutter got into the switch and it stuck and would not work.

If you let the board soak long enough for an hour or a bit more the rosin just dissolve's and when you lift it out you tell there is nothing there,the Krud Kutter will not hurt caps resistors leds or triodes whether they are threw hole or smd.

The only thing Krud Kutter will attack is polystyrene witch is just white Styrofoam,I also find you can get many use's from a mixed up batch,I have also found it works very very very fast if I'm mixing up a batch for the first time and I use warm water with the Krud Kutter,I have thought about using a Crock Pot or slow cooker to heat the mixture the same way a Sonic cleaner works but need to find out the temps a sonic cleaner works at and also if a Crock Pot or Slow Cooker can be turned down to a low enough temperature.

Here is a link to the product and just as a side not the original stuff has worked great on all house hold cleaning task's and just plain and simply works great on just about any task you throw at it.

https://www.homedepot.ca/en/home/p.krud-kutter-original-cleaner-degreaser-spray-946ml.1000831021.html


--- Quote from: joeyjoejoe on September 20, 2018, 01:08:50 pm ---Is there a no-clean flux that cleans easily with Isopropyl?

I have ChipQuik SMD tacky flux, and IPA doesn't seem to clean it after even with a nylon brush. Board stays tacky.

I'd prefer to get a flux that cleans easily with IPA as IPA is something that I keep around the house easily enough and use for many other things.

--- End quote ---
Raj:
Start with a cheapest one while soldering practice boards with components as small as 0402 or even 0201
wade7575:
@nanofrog I was just wondering if you can tell me if there is anything you need to watch for when using Toluene and MEK as far as it harming anything on the board,do you mix them together or do you use them separately.


HB9EVI:
So far I just tried cheap solder paste 63/37 from aliexpress. It dries out quite fast but when fresh, it behaves well, residue removes with IPA

Otherwise, since I have a rework station, I completely stopped bothering to solder smd chips with the solder iron; they pretty much solder by themselves with hot air, the biggest issue when you get newly into it is finding the right amount of paste; wick is in every case a good thing.
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