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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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lead free solder
I am in the US and just doing my own repairs and building. Do I need to use any of the lead free solder to repair the boards that were made usign the lead free solder? I have not bought any yet and have been practicing witht he SMD on old computer boards. That stuff seems a pain to work with compaired to the 'regular' tin/lead that I have been using for the last 50 years. I have been thinking about getting some for the power transistors and resistors where there is a lot of heat build up but not sure if that application would even be worth the trouble. |
#2
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lead free solder
On 30/04/2016 15:37, Ralph Mowery wrote:
I am in the US and just doing my own repairs and building. Do I need to use any of the lead free solder to repair the boards that were made usign the lead free solder? I have not bought any yet and have been practicing witht he SMD on old computer boards. That stuff seems a pain to work with compaired to the 'regular' tin/lead that I have been using for the last 50 years. I have been thinking about getting some for the power transistors and resistors where there is a lot of heat build up but not sure if that application would even be worth the trouble. If you are just doing repairs or mods to PbF stuff then use SAC (Tin +Silver+Copper) solder, the cost would be prohibitive for complete new build soldering. |
#3
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lead free solder
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#4
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lead free solder
In article ,
Ralph Mowery wrote: I have not bought any yet and have been practicing witht he SMD on old computer boards. That stuff seems a pain to work with compaired to the 'regular' tin/lead that I have been using for the last 50 years. Ralph- I sympathize! The problem with using tin-lead solder with SMD, is that lead "amalgamates" with the silver contacts of surface mount devices, resulting in a non-conductive layer between the device and the circuit. While tin-lead-copper solder may help, it would be better to use lead-free. It may work better if you use a temperature-controlled iron, capable of higher temperatures than your old iron. Fred |
#6
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lead free solder
Ralph Mowery wrote:
As it is just for my own use at home I am not worried about the legal Rohs part. OK, just for your own use, you can do repairs with PbSn solder on assemblies made originally with Pb free. I do this all the time, never had a problem. You can also, in most cases, do repairs on gear that was made with PbSn solder using SAC305. This does require higher temperatures, but when hand soldering one lead at a time, usually there's no harm. Jon |
#7
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lead free solder
Fred McKenzie wrote:
In article , Ralph Mowery wrote: I have not bought any yet and have been practicing witht he SMD on old computer boards. That stuff seems a pain to work with compaired to the 'regular' tin/lead that I have been using for the last 50 years. Ralph- I sympathize! The problem with using tin-lead solder with SMD, is that lead "amalgamates" with the silver contacts of surface mount devices, resulting in a non-conductive layer between the device and the circuit. While tin-lead-copper solder may help, it would be better to use lead-free. It may work better if you use a temperature-controlled iron, capable of higher temperatures than your old iron. Actually, if it amalgamates, you are fine. That essentially means it has made an alloy. Pbf component leads usually do NOT have silver on them, just Tin. Now, GOLD is a problem, a certain percent of gold dissolved into a solder joint can cause brittle structures that fracture under thermal or mechanical stress. They call this intermetallics. But, I've never heard of this with silver. I've done tons of boards with SMDs using PbSn solder, and had no trouble with it. One time ONLY, I got talked into trying gold flash plating on the circuit boards, and had HUGE problems with joints that never flowed, or became brittle. The fix was, desolder, lift the lead, scrape the pad down to bare copper, tin the pad, fold the lead back down and solder. UGGGH! Still gives me nightmares! Jon |
#8
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lead free solder
In article , elson@pico-
systems.com says... Fred McKenzie wrote: In article , Ralph Mowery wrote: I have not bought any yet and have been practicing witht he SMD on old computer boards. That stuff seems a pain to work with compaired to the 'regular' tin/lead that I have been using for the last 50 years. Ralph- I sympathize! The problem with using tin-lead solder with SMD, is that lead "amalgamates" with the silver contacts of surface mount devices, resulting in a non-conductive layer between the device and the circuit. While tin-lead-copper solder may help, it would be better to use lead-free. It may work better if you use a temperature-controlled iron, capable of higher temperatures than your old iron. Actually, if it amalgamates, you are fine. That essentially means it has made an alloy. Pbf component leads usually do NOT have silver on them, just Tin. Now, GOLD is a problem, a certain percent of gold dissolved into a solder joint can cause brittle structures that fracture under thermal or mechanical stress. They call this intermetallics. But, I've never heard of this with silver. I've done tons of boards with SMDs using PbSn solder, and had no trouble with it. One time ONLY, I got talked into trying gold flash plating on the circuit boards, and had HUGE problems with joints that never flowed, or became brittle. The fix was, desolder, lift the lead, scrape the pad down to bare copper, tin the pad, fold the lead back down and solder. UGGGH! Still gives me nightmares! Jon I have ran into the gold problem. Only "simple" cure I know of is to just scrape it to the base material. I never gave the solder any other thought before just use the 60/40 or beter if around 63/37 and rosin flux, but now with that lead free stuff comming in and components having to be made to the Rohs standards it is time to do some asking about the mechanics of it. Seems there are about half a dozen or more mixes now without the lead. There is one other problem I have seen , not with solder, but tin plated items. The tin "whiskers'. Probably will be a problem with the tin/silver and no lead solder. I have read that the military and space agencies still use the tin/lead to not have that problem. I know I have to use a lot more heat on the irons on that lead free stuff. |
#9
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lead free solder
"Amalgamates" *Does Not* mean that an alloy has been formed. An Amalgam is essentially a solid colloid whereby the *separate* properties of the components makes a mixture that does not behave as either. The best example of this that is easily understood is Dental Amalgam, which is a mixture of silver, tin, copper and zinc, indium and other materials *as a powder* mixed 1:1 with mercury. The mix is pressed into place, whereupon the mercury is displaced and the rest of the mixture hardens. But, it is NOT an alloy. The various components partially dissolve in the mercury and bind to each other as a result. Kinda-sorta like sticky bits of candy would bind to each other if made wet. But, the individual bits of candy never dissolve entirely, and except at the direct interface, could never be described as an alloy. Or, if you must, somewhat like concrete. The components, sand, gravel, water, and cement *cure* (NOT dry) into an amalgam - but they are NOT an alloy.
This is an obscure point, but important in this context. The potential for a non-conductive oxide to form is real as each component of the amalgam remains discrete in its behavior at the chemical level. The reason that gold is used is that it is more resistant than any other of the noble metals to 'dissolving' into anything, forming an oxide or otherwise degrading. If it is attacked by something, that something will be quite toxic or dangerous in its own right. Those compounds would include chlorine, mercury, cyanide and reactants of same. Gold often does not solder well, true, but that depends much on how how it is alloyed and its purity. 24 karat (pure) gold tends to solder quite easily, if gotten hot enough, but is also very expensive, very soft and for those reasons seldom used. 10 karat gold - the lowest that can still be called 'gold' solders badly unless very high silver-content solder is used, and typically requires a flame. Silver Brazing would be a better description. Gold is seldom used in soldered components as there is no reason to do so. The only real reason for gold (as it is a poor conductor relative to silver or copper) is its resistance to corrosion on contact-type connectors - jacks, plugs and switches. Soldering *to* a gold-flashed lug or pad is asking for trouble for all sorts of reasons, some obvious, some not so much. This is basic high-school chemistry - at least when I was in school. Peter Wieck Melrose Park, PA |
#10
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lead free solder
"Ralph Mowery" wrote in message .net... I am in the US and just doing my own repairs and building. Do I need to use any of the lead free solder to repair the boards that were made usign the lead free solder? Within the EU; hobby use and repairing originally lead solder equipment is among the exemptions. Never bothered swotting up on the laws elsewhere, but I think America and Asia comply with RoHS purely so they can export to the EU. RoHS certification is expensive enough, but certification guaranteeing that cross contamination can't happen in a manufacturing plant that uses both processes, is much more costly - its much cheaper to impose blanket compliance with RoHS, even for goods that don't have to comply. Mixing them depends on individual compositions - visual appearance of the finished joint is a good indication whether you got away with it. |
#11
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lead free solder
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#12
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lead free solder
In article ,
says... The reason that gold is used is that it is more resistant than any other of the noble metals to 'dissolving' into anything, forming an oxide or otherwise degrading. If it is attacked by something, that something will be quite toxic or dangerous in its own right. Those compounds would include chlorine, mercury, cyanide and reactants of same. I think I have mentioned "purple plague" here before. https://en.wikipedia.org/wiki/Gold-a..._intermetallic. I learnt about it decades ago when working on experimental conducting films. I thought that gold was tricky to solder precisely because it did tend to dissolve unless the solder was already loaded with gold. Mike. |
#13
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lead free solder
Ralph Mowery wrote:
There is one other problem I have seen , not with solder, but tin plated items. The tin "whiskers'. Probably will be a problem with the tin/silver and no lead solder. Pure tin solder, if not processed hot enough to anneal the Tin, can get REAL bad. Part of the reason for the tin/silver solder is to reduce the whisker formation, and it seems to work. I had some Xilinx chips which had pure tin lead plating, and I was processing them at PbSn temperatures, and the LEADS, not the solder joints, had whiskers at the bends in the leads, as this is where the stressed tin was. Xilinx suggested hotter soldering temps. Jon |
#14
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lead free solder
On Saturday, April 30, 2016 at 6:00:05 PM UTC-4, MJC wrote:
I thought that gold was tricky to solder precisely because it did tend to dissolve unless the solder was already loaded with gold. Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve. Peter Wieck Melrose Park, PA |
#15
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lead free solder
wrote:
MJC wrote: I thought that gold was tricky to solder precisely because it did tend to dissolve unless the solder was already loaded with gold. Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve. ** In fact gold dissolves readily in tin and hence solder. Normally, gold plated parts have a nickel underlay which does not readily dissolve to form an alloy with solder. This results in joints that have poor mechanical strength. https://en.wikipedia.org/wiki/Gold_p...ldering_issues http://www.indium.com/blog/intermeta...-soldering.php ..... Phil |
#16
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lead free solder
On Sunday, May 1, 2016 at 10:01:04 PM UTC-4, Phil Allison wrote:
wrote: MJC wrote: I thought that gold was tricky to solder precisely because it did tend to dissolve unless the solder was already loaded with gold. Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve. ** In fact gold dissolves readily in tin and hence solder. Normally, gold plated parts have a nickel underlay which does not readily dissolve to form an alloy with solder. This results in joints that have poor mechanical strength. https://en.wikipedia.org/wiki/Gold_p...ldering_issues http://www.indium.com/blog/intermeta...-soldering.php .... Phil Phil: Jewelry grade gold electroplate uses a three-metal process, first copper, then nickel, then gold. Electronic plating for other than switches and mechanical connectors DOES NOT go through this process as it would be far too costly, take too much time and often add too much thickness. We are discussing microns here, and they matter. Nor is appearance a concern. For flash plating electronic solder connectors, the gold is deposited directly on the copper. http://download.springer.com/static/...e5a9 65d0d81b Is a link that will take you to an article on how gold operates at/less than one micron of thickness - whereupon you are correct, and at greater thicknesses, where the solder simply does not stick. Gold is a wretched soldering base for electronic purposes using traditional tin-based solders. As I stated previously, for any number of reasons, some not obvious. Peter Wieck Melrose Park, PA |
#17
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lead free solder
wrote:
Phil: ** That is patronising and offensive. Address all posts to the NG. Jewelry grade gold electroplate uses a three-metal process, ** Wrong topic. For flash plating electronic solder connectors, the gold is deposited directly on the copper. ** Is it ? Gold is a wretched soldering base for electronic purposes using traditional tin-based solders. ** That is a dramatic about face, if I ever saw one. ..... Phil |
#18
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lead free solder
On Monday, May 2, 2016 at 8:45:29 AM UTC-4, Phil Allison wrote:
wrote: ** That is a dramatic about face, if I ever saw one. Please show me where I have _ever_ endorsed, suggested or implied that gold is a useful soldering base for any sort of electronics purposes? NASA has used gold as a soldering base in space and on the moon due to its tolerance of extreme heat, but they had to go to extraordinary lengths to make it reliable mechanically. Otherwise, not so much. Hence the cost per cubic centimeter of NASA equipment exceeds even that of the US military. Silver-solder (real tin-free silver solder) is fine for gold, and why it is used for jewelry making. And as I also stated, silver brazing is more accurate as a flame is necessary typically - and in most cases, a flame is not appropriate for electronics. Further to this, if one looks at what happens to very thin (=1 micron) the gold "leaches" rather than dissolves - and may be easily recovered by any number of methods, not typical of a true solution. The heat breaks the plate bond to the copper substrate and the colloid so formed is very brittle. http://mysite.du.edu/~jcalvert/phys/copper.htm gives much more information on the chemistry (or lack thereof) of gold and as it compares to the other "noble" metals. Peter Wieck Melrose Park, PA |
#19
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lead free solder
On Saturday, April 30, 2016 at 2:00:53 PM UTC-4, Jon Elson wrote:
Ralph Mowery wrote: As it is just for my own use at home I am not worried about the legal Rohs part. OK, just for your own use, you can do repairs with PbSn solder on assemblies made originally with Pb free. I do this all the time, never had a problem. Me too, the amalgamate talk makes me wonder though. George H. You can also, in most cases, do repairs on gear that was made with PbSn solder using SAC305. This does require higher temperatures, but when hand soldering one lead at a time, usually there's no harm. Jon |
#20
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lead free solder
wrote in message ... On Saturday, April 30, 2016 at 2:00:53 PM UTC-4, Jon Elson wrote: Ralph Mowery wrote: As it is just for my own use at home I am not worried about the legal Rohs part. OK, just for your own use, you can do repairs with PbSn solder on assemblies made originally with Pb free. I do this all the time, never had a problem. Me too, the amalgamate talk makes me wonder though. Reworking lead free with 60/40 sometimes gives a grainy finish that looks even more dodgy than the original lead free. When I was in TV repair, most Asian manufacturers had converted before most people in the UK had even heard of RoHS. (but it took the Asian manufacturers a lot longer to get it right). My introduction to lead free solder was a steady stream of TVs with bizzare random faults that defied any attempt at logical diagnosis - going over the soldering fixed them as if by magic. With Hitachi sets; you could push down on a component and the whole solder fillet would detach from the other side, that revealed a thin black layer of oxide on the copper. On Sony sets; the solder looked as good as lead free ever can - but going over the soldering fixed over 90% of all faults. During that time I routinely used 60/40 - I didn't get many bounced repairs, and not many of those had anything to do with solder. |
#21
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lead free solder
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#23
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lead free solder
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#24
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lead free solder
On Monday, May 2, 2016 at 2:09:22 PM UTC-4, Ian Field wrote:
wrote in message ... On Saturday, April 30, 2016 at 2:00:53 PM UTC-4, Jon Elson wrote: Ralph Mowery wrote: As it is just for my own use at home I am not worried about the legal Rohs part. OK, just for your own use, you can do repairs with PbSn solder on assemblies made originally with Pb free. I do this all the time, never had a problem. Me too, the amalgamate talk makes me wonder though. Reworking lead free with 60/40 sometimes gives a grainy finish that looks even more dodgy than the original lead free. When I was in TV repair, most Asian manufacturers had converted before most people in the UK had even heard of RoHS. (but it took the Asian manufacturers a lot longer to get it right). My introduction to lead free solder was a steady stream of TVs with bizzare random faults that defied any attempt at logical diagnosis - going over the soldering fixed them as if by magic. With Hitachi sets; you could push down on a component and the whole solder fillet would detach from the other side, that revealed a thin black layer of oxide on the copper. On Sony sets; the solder looked as good as lead free ever can - but going over the soldering fixed over 90% of all faults. During that time I routinely used 60/40 - I didn't get many bounced repairs, and not many of those had anything to do with solder. Thanks Ian, I'm a bit confused by your response though. It's starts by saying 60/40 on lead free is dodgy, and ends by saying you had few problems when using it. George H. |
#26
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lead free solder
"Ralph Mowery" wrote in message k.net... In article , says... Last time I checked - RCA had been taken over by the French Thomson firm. Last Hitachi I looked inside; the innards were made by the Turkish Vestel company - while researching servicing info; I learned that quite a few big name manufacturers stick their badge on the very same chassis I found. That is one big problem for me. I never know who or where anything is really made. I was repairing some CB radios for friends around 1970 and found even then the same insides were put into different cabinets for different brands. Sometimes even the same color wires were used. The Brand names are often sold and moved to a different country so the quality may or may not be worse. AFAIK: there's wheelers & dealers brokering brand names. Bush wasn't the Rolls Royce of consumer electronics, but it was a well respected brand. Its now one of quite a few badges that get stuck on very cheap & very nasty Vestel equipment like the one I found. |
#27
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lead free solder
"N_Cook" wrote in message ... On 03/05/2016 13:25, wrote: On Monday, May 2, 2016 at 2:09:22 PM UTC-4, Ian Field wrote: wrote in message ... On Saturday, April 30, 2016 at 2:00:53 PM UTC-4, Jon Elson wrote: Ralph Mowery wrote: As it is just for my own use at home I am not worried about the legal Rohs part. OK, just for your own use, you can do repairs with PbSn solder on assemblies made originally with Pb free. I do this all the time, never had a problem. Me too, the amalgamate talk makes me wonder though. Reworking lead free with 60/40 sometimes gives a grainy finish that looks even more dodgy than the original lead free. When I was in TV repair, most Asian manufacturers had converted before most people in the UK had even heard of RoHS. (but it took the Asian manufacturers a lot longer to get it right). My introduction to lead free solder was a steady stream of TVs with bizzare random faults that defied any attempt at logical diagnosis - going over the soldering fixed them as if by magic. With Hitachi sets; you could push down on a component and the whole solder fillet would detach from the other side, that revealed a thin black layer of oxide on the copper. On Sony sets; the solder looked as good as lead free ever can - but going over the soldering fixed over 90% of all faults. During that time I routinely used 60/40 - I didn't get many bounced repairs, and not many of those had anything to do with solder. Thanks Ian, I'm a bit confused by your response though. It's starts by saying 60/40 on lead free is dodgy, and ends by saying you had few problems when using it. George H. 60/40 on lead free is dodgy, PbF is dodgey, PbF on PbF is dodgey, SAC on PbF is dodgey, you do your own thing with fingers crossed and monitor for bouncers over the next few years. They do seem to be getting better at lead free - at one point, the bulk of TVs going to landfill increased five-fold because of dodgy soldering. They are gradually getting that figure down a bit. Apart from the fact that manufacturing was taking lead out of the environment and binding into a relatively stable alloy - what difference is RoHS going to make with rain and hail lashed lead roofs running into the water table. There's been about 100 yrs of the landed gentry peppering agricultural land with lead shot. They're most unlikely to have got all the lead pipes that were used upto the 50s - in the UK; they're still discovering Roman lead water ducting. The other side of the coin was lead in petrol - the petrochemical industry lead procurement was in tons, and the number had a lot of noughts on the end. That lead was being pumped in the air as particulates for us all to breathe. |
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