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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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22nd Feb 2018, 2:06 pm | #1 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
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Solder surprises...
Hi folks,
I had a couple of unusual batches of solder in the post this week. Unusual odds, and I thought I'd probe around to see what others have been experiencing. However I don't want this to be a whingeing thread, more about the technical aspects of what people have been surprised by and which brands etc are the most highly rated. The two that I received had a very high melting point, one close to 450 degrees. Given that even power semiconductors can be soldered for seconds up to 350 degrees, this is pretty useless except for plumbing. It had poor thermal conductivity and until I raised the temperature of the iron, it left clumps of half-melted alloy around the work. It was a complete mess until I added an external flux in quantity and raised the temp as described. I will still have to remove it and reapply with an alloy that I trust, once I've received it in the post. The other had a slightly lower melting temperature but like the other, also had poor flow qualities and high surface tension, such that it would not easily bond with the prepared surfaces. It crystallises to a dull, textured grey surface, which is ugly in my view. It's not that I am now stuck. One supplier has agreed to take back the solder and the other has refunded me without even asking. It's more that I'm intrigued to know what these sorts of solders contain, as well as others' experiences. I'm guessing largely tin, perhaps with Cu or Zn in small quantity? My preferred solder is tin/lead/Ag (the silver is around 2%).
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Al Last edited by Al (astral highway); 22nd Feb 2018 at 2:26 pm. |
22nd Feb 2018, 2:19 pm | #2 |
Dekatron
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Location: Oxford, UK.
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Re: Solder surprises...
Hi Al,
Were these reputable brands from big name suppliers? Were they sold as traditional tin/lead with resin-core flux? N. |
22nd Feb 2018, 2:23 pm | #3 |
Hexode
Join Date: Apr 2017
Location: Falkirk, Stirling, UK.
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Re: Solder surprises...
In my experience the cheap unbranded stuff from China is very bad, I think it must be made from recycled materials full of impurities etc. I'm not sure if that's what you got but it sounds like it. I'm no expert but the silverline stuff seems to work ok.
Cameron |
22nd Feb 2018, 2:43 pm | #4 |
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Re: Solder surprises...
I doubt that any tin/lead alloy soft solder would have a melting point of 450 degrees, which I assume is degrees centigrade?
Have you perhaps purchased a hard solder such as silver solder, which should not be confused with silver loaded soft solder?
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
22nd Feb 2018, 3:28 pm | #5 |
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Re: Solder surprises...
I have some Ersin Multicore that has oxidised and is as you describe, blobby and won't flow or stick.
I think its a problem of being kept in a damp environment. |
22nd Feb 2018, 3:46 pm | #6 |
Dekatron
Join Date: Nov 2010
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Re: Solder surprises...
In the opposite direction, there are ultralow melting point eutectics. For example Wood's metal https://www.reade.com/products/wood-s-metal-alloy . That is also used for making superconducting joints for NMR magnets.
There are are a range of low melting point alloys down to very low melting points of 40-ish C, used by SME for bending tone arm tubes. Fill with molten alloy and allow to cool, bend tube in a jig, melt out alloy in a hot water bath. Re-use. Craig |
22nd Feb 2018, 4:20 pm | #7 | |
Dekatron
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Re: Solder surprises...
Quote:
It isn't an error of mine, but curiously, a double experience of being offered a tin/lead multi-core flux solder which clearly isn't that at all. Hence my curiosity (particularly with a background in metals refining) about which alloys could pass off in looks as Sn/Pb but in fact be other alloys entirely. I'm not stuck, as I have returned to my usual supplier of Sn/Pb/Ag (2%), which I like as it flows beautifully and is strong enough to tack large assemblies together of make heavy-gauge ground planes. So my question isn't for a fix for my benefit, rather a wider discussion of other's experiences and possible explanations.
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22nd Feb 2018, 4:22 pm | #8 |
Dekatron
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Re: Solder surprises...
Interesting, thanks Sam. And that's a great and reputable brand. I wonder just how moisture interacts with it to cause such a problem. We could assume any damp would boil off within seconds of contact with such a point source of heat.
I'm open and not discrediting your theory, just interested in what might be happening at a molecular level to corrupt the normal behaviour of the solder.
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Al |
22nd Feb 2018, 4:29 pm | #9 | |
Dekatron
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Re: Solder surprises...
Hey, Nick, no not from suppliers I'm familiar with.
Quote:
One is an absolute pig's breakfast to reverse. It barely flowed, left big clumps and had to go above 450 degrees C to retract the blobs. It still looks horrendous and I am going to wick it all out and wait for my new batch of a source I'm familiar with. Curiously, this (normal) source isn't even branded, but is sold in 1-5metre lengths. It makes astonishingly fluid solder when heated to even 285 degrees and the joints are perfect and strong, and beautifully bright and clean. I am pretty perfectionist about the integrity of soldered joints. ( Like some others on the forum, I often turn the iron up ( to 320 degrees or so in my case) for heavier work, things like tag-strips and big power semiconductor leads, because the soldering time is maybe just a second instead of several seconds at a lower temperature. With IC's I get a clean bond in less than a second by using fine gauge solder, but this is going OT).
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22nd Feb 2018, 4:32 pm | #10 |
Octode
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Re: Solder surprises...
Not possibly completely on topic but a contract wireman I used to know always referred to the 22 swg tinned copper wire used for board links as "non melting gauge wire"
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22nd Feb 2018, 4:34 pm | #11 |
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Re: Solder surprises...
I haven't bought any 60/40 solder for years, as I stocked up on it when it was rumoured that it was to be banned.
Any solder will give a messy, lumpy or crystalline type joint it not heated enough. That includes heating the metal you're soldering to as well as the solder. To solder a wire to a tag bent up from a chassis requires a lot more heat than soldering a resistor to a solder tag on a tag strip. I'm talking heat capacity here, not temperature. Does the solder feel soft? ie can it be bent without spring back? Is it magnetic?
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
22nd Feb 2018, 5:42 pm | #12 |
Dekatron
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Re: Solder surprises...
Hey Graham, I’m forever making sound , sometimes beautiful solder joints, often with very heavy materials like busbar, as well as large ground planes with thick (12SWG) wire.
This isn’t about technique or practical skill, it’s about a mystery and a misleading product description description . Yes, both solders are malleable and plausible in appearance but as I say , require ridiculous levels of heat from a point source for a messy, lacklustre result . I have used plumbing solder in the past upgrading the cold water supply and central heating system of my old house , and did quite a lot of brazing with Yorkshire fittings, etc, so have those experiences using a propane / butane torch for comparison , where I achieved good results and a neat finish . I usually use .4mm for fine work and 1mm or above for heavy work. I know how to prep heavy materials appropriately and this is the first time since I was a teenager that I’ve had such confusing results!
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Al |
22nd Feb 2018, 6:53 pm | #13 |
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Re: Solder surprises...
Yes, it is centigrade.
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Al |
22nd Feb 2018, 8:59 pm | #14 |
Dekatron
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Re: Solder surprises...
Don’t forget the HMP (high melting point) solder used on dropper resistors so it didn’t melt when the dropper got hot. Always had some in the tool kit when doing telly repairs in the 60’s.
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22nd Feb 2018, 9:15 pm | #15 |
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Re: Solder surprises...
I just checked RS Components' range of HMP solders. Those with the highest melting point melt at around 300 degrees C.
There must be something other than lead and tin in the OP's solder. Steel, copper or zinc perhaps? It wouldn't make sense to use silver in a "fake" solder.
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
22nd Feb 2018, 9:28 pm | #16 |
Heptode
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Re: Solder surprises...
Slightly off topic but perhaps worth mentioning, Like Graham I have a stock of unused solder awaiting use.
I was concerned about it oxidizing so I popped the reel in a clean jam jar in the hope that this might slow any oxidization, or at least it keeps it clean! Fake news ...Fake solder! |
22nd Feb 2018, 10:34 pm | #17 | |
Dekatron
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Re: Solder surprises...
Quote:
I suggested Zn or Cu in my OP and was curious whether others could corroborate this
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22nd Feb 2018, 11:34 pm | #18 | |
Nonode
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Re: Solder surprises...
Quote:
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23rd Feb 2018, 3:27 pm | #19 |
Dekatron
Join Date: Nov 2006
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Re: Solder surprises...
I can see the value of HMP solder in high power TX tank circuits.
I do wonder, though , that these solders do not produce a dull, grey surface with a brittle-looking crystalline structure. This appearance is typical of a ‘dry’ joint, even though both surfaces were immaculately cleaned, preheated extensively and additional flux applied when the solder didn’t ‘flow’ easily. I have looked inside mil-spec transmitters in the past and never saw what looked like a dull, dry joint. In any case , the non-functionsl solders I describe here are simple instances of a supplier describing as conventional tin/lead multiflux solder a solder that is clearly far from being such a thing. Inappropriate descriptions are quite common and not, in my experience, not even deliberately misleading. I’ve got my money back so I’m not going to obsess about something which isn’t such a big issues once my familiar , preferred solder arrives in the post. As there is no further illumination on the possible alloy contained in my ‘faulty’ solders and my experience doesn’t seem to be a common finding among forum members, I’m happy for the thread to close .
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Al |
23rd Feb 2018, 3:34 pm | #20 |
Dekatron
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Re: Solder surprises...
Are you sure the seller has supplied unleaded solder with a leaded label on the reel?
Have a look at a few modern boards and see if it looks the same. |