Which solder formulation should I use?

**Penfold** · 04-03-2008, 01:00 PM

Right now I have a dilemma. I have heard that lead free solder, solder containing silver, and the leaded solders are good and bad in their own respects. Just out of curiousity, what does the DIYC community use?

Also there is a possibility of getting my hands on 93% pure silver solder.

I have 93% tin, 4% silver I got from Radio Shack a while back that has a flux core, but I am not sure how this will solder as I have never used this.

**grages** · 04-03-2008, 04:42 PM

This is what I bought.

Part Number: 4900-227G

M.G. Chemicals designed its no clean Lead-Free Solder with Sn/Ag/Cu (Tin/Silver/Copper) alloys as a lead-free alternative for the standard Tin and Lead solder. These alloys conform to and exceed the impurity requirements of J-Std-006 and all other relevant international standards such as RoHS.
Lead free
Complies with RoHS
Exceeds the impurity requirements of J-Std-006
No Clean flux
21 Gauge, 0.032 â€œ diameters
Excellent wettability
Hard non-conductive residues Flux Percentage
M.G. Chemicals Lead Free Solder utilizes a state-of-the-art automatic wire extrusion and wire drawing machines to manufacture consistent solder. The introduction of flux core in the wire extrusion process involves constant monitoring of flux percentage to ensure minimal flux voids and irregular wire. Typical flux percentage for our Lead Free Solder is 2.0-4.0%.
Flux Core
A unique flux system was specifically used for high temperature lead free alloys. It provides the fluxing activity levels that promote fast wetting action and maximum wetting spread. Utilizing synthetically refined resin and very effective activator that wets and spreads like an RA type. This special activator exhibits virtually no spattering. Activator conforms to J-STD-004, REL0.Cleaning Flux core is a no clean formulation therefore the residues do not need to be removed for typical applications.

Other Related Products:
Circuit Specialists Inc. - 220 S Country Club Drive #2 Mesa, AZ 85210
Phone: 800-528-1417 / 480-464-2485 Fax: 480-464-5824 Email: jr@cir.com

**g2ktcf** · 08-03-2009, 04:26 AM

I keep seeing these post pop up...but did you guys every try this? I am in the UK currently and it looks like I left my 60/40 at home. The only local supply looks to be lead free (Tin/Copper).

Any feedback on how this melts and flows?

Thanks,
Chris

**omzig** · 08-03-2009, 10:53 AM

Personally, I wouldn't use the lead-free unless I had no other choice. It has a much higher melting point than leaded solders. The irons that they make for lead-free solder have a better rebound rate so that they can keep the tip hot enough. Then there is always the problem of tin whiskers with lead-free solders. This was one of reasons for adding lead to solder in the first place. I wonder how much of a problem this is going to be in Europe years down the road now that lead solder is prohibited.

I have tried several formulations and IMO by far the best performance is from 63/37 Sn/Pb. It melts easier and hardens immediately after removing the heat. 60/40 Sn/Pb is next best. I bought a case of 60/40 real cheap a while back when a electronics store was going out of business, so that's what I've been using for years now. I would be using 63/37 if I didn't have so much 60/40 on hand.

The 93% silver solder would be fine if you are soldering with a torch! The only real benefit in using it would be strength or high temperature applications, neither of which is the case with what we do.

**ukewarrior** · 08-03-2009, 01:09 PM

I completely agree with Don.

I have found lead free solder to be hard to use, hard to flow, and certainly requires higher temperatures.

This may be fine for the professional industry, but none of these traits are good for the hobbyist.

**ErnieHorning** · 08-03-2009, 02:00 PM

I only use lead free solder professionally at work because we are required to follow the ROHS spec. I hate it! It does require a bit more heat, but it doesn’t tolerate it for very long. You have to get it to melt and flow very quickly or it looks like a cold solder joint. I find that it doesn’t hold nearly as well either. It takes much less force to tear a part off the board.

Whiskers can be a problem. I do a lot of environmental testing at work. I know for a fact that I can get whisker growth to form by freezing a board and the placing it in a warm humid environment while the board is powered up. I can short out a board in as little as 10 minutes. If you live in a cold climate, it’s possible to have frost form on your board at night and melt from the sun in the morning and have condensation momentarily form on the board. It may take a few repeats of this for a problem to occur. If it’s in a high current area, it will go away like a miniature fuse. If not, it can eventually cause a problem.

I make my own boards and I find that lead free is especially troublesome on bare copper. You need the higher heat to melt the solder, but the higher heat also causes the copper to oxidize very fast so that the solder won’t adhere.

I have a lifetime stock of 60/40 at home. I prefer this over any kind of lead free any day.

BTW, your government that imposed this on all of us doesn’t use it. All military circuit boards are still required to be soldered with lead solder. Even if they purchase off the shelf equipment, it has to be made with lead solder. It’s getting harder to get tin/lead parts for military manufacturing.

The original reason for switching was to prevent lead contamination of the ground and potentially of drinking water. This was apparently was government BS with little verification. Independent testing found that the lead does not dissolve and leach into the ground. It stays right where it was. Lead was also much easier to recycle than no lead. Now we’re stuck with it and it’s problems.