Lead free solder.

I just heard at a Mac User's meeting yesterday that Apple is having trouble with the iBook series due to that problem. I haven't confirmed this, so for now its a rumor. I've still got a lot of 60/40 around, and nothing I've done has been shipped to Europe, so I'm still using the 60/40. I did repair a welder that got sent back to Israel, come to think of it, but it was old and originally made with lead solder.

My biggest problem with solder has been (I think) the lack of quality/quantity of flux in solders from the Far East.

Dick

Standard 60/40 can still be used for the repair of equipment that was made using this grade of solder it is only new goods. The military, aircraft (avionics) can still use it and and safety critical equipment. Also an amateur enthusiast can use 60/40 for personal project use. I agree that the far eastern stuff can be abysmal.

Dear BrainWave,

Thank you for asking this question. Since last few months this "Lead Free" or ROHS has created lot of queries in my minds also but I was not able to put it. Still I am having very basic doubt 'What is Lead Free Soldering?' How it is done etc. Can someone explain this?

Lead Free solder is a requirement for appliances and electronic goods sold in the EEC. The EEC have issued a directive, related to the Restriction of Haradous Substances (RoHS). This includes lead (and other heavy metals) and certain chemicals.

Lead Free solder can still be applied using conventional soldering methods and equipment but it has slightly different characteristics to solder containing lead. The temperature needs to be a little higher, it does not flow as well and the temperature band the solder operates in for best results is smaller.

Quite a lot of you indulge in electronics professionally do you use lead free soldering now and if so how does it compare against the old regular 60/40 type?

I have used nothing but lead free solder for almost all applications for a number of years and was a half-tinned expert in a former live. Tin, copper, silver alloys are better than 60/40 as it stays bright and does not oxidize as the oldtime solder.

Plumbers and pipe-fitters use a lead free alloy with a water soluble flux to match.

Kester Solders <http://www.kester.com/en-us/news/rlss_detail.aspx?prid=123>

Oatey Solders <http://www.imex.com/catalog/oatey-c.html&gt;

Study of Lead Free Solders <http://www.aimsolder.com/techarticles/A%20Study%20of%20Lead-Free%20Solder%20Alloys.pdf>

Currently a new plastic water suppy tubing/piping is coming into vogue to replace copper. Easier to make long runs, no leaky joints, just end termination fittings at fixtures or transition(s) to metal are required.

This tubing is also being installed as in/under floor radiant heating systems. Known as "Cross-Linked Polyethylene (PEX) Water Supply Piping" see:

<http://www.toolbase.org/Technology-Inventory/Plumbing/cross-linked-polyethylene-pex>

The UK has used plastic pipe for under ground supplies for the last 25 years ("Alkathene" trade name) a blue color plastic normally 25 mm 1" internal diameter. This replaced screw jointed iron. Some plumbers us another plastic pipe to replace copper for internal work with push fit joints I do not like to trust it. A good solder or compression fitting is better.

Brain Wave:

I would advise caution to using the "blue" plastic piping that you suggested is being used in Europe for the last 25 years. Our neighborhood was piped with the "Blue Max" polysulfone plastic pipe in 1986. The piping system became brittle after 15 years. As the homes settled the piping system would get into a bind and would break causing big problems. Failures at the joints were also found away from the home foundations. Shell Chemical had settled a class action suit for the owners of this "Blue Max" piping system. To date my neighborhood has had over 40 failures including two failures on my own property.

Sorry to hear of this but I have never before heard of any problems. It is an accepted material used and now made the only available option by the water supply industry. May be local soil conditions or the depth of burial are factors. It is recommended to lay the pipe at a min depth of 30 inches 750mm. Frost can make it embrittle and UV will add to this situation. I know where the very first pipe was used and this is now 35 years or more ago. It has not failed. I do not know you local conditions nor where you live country district. I do know that there must be some thing very specific to you own cicumstances to make this happen. My father worked in the water supply industry for several years and when our old iron pipe corroded and then burst we replaced in blue plastic. That is over 20 years ago with no failure.

Begging pardon as this is in the recent "done it, been there, got the T-shirt, which is now on eBay" category:

"Alkathene" is an earlier standard of more rigid plastic water supply pipe in imperial sizes in black, whereas the current standard is blue PVC in metric sizes. Imperial alkathene is a right %$@& to join to the new standard as it requires adaptor fittings, which are not widely available in the UK, though some specialised builders' merchants do stock them. One can, if the wind is in the right direction, just about put 3/4" alkathene into metric brass 22mm compression fittings and get away with it, though no responsible plumber would do this and risk the reputation damage.

Ever so sorry for the interruption. Please continue with this thread.

Hi Brainwave,

We manufacture small transformers, inductors and the like in Australia.

We are still using 60/40 solder because to date we have not found a reliable lead free solder to take its place. Recently one of our competitors had a major recall because of lead free solder in their electronic power supplies.

It is interesting to note that leaded solder is still permitted in medical, aeronautical, military and some automotive applications - in other words where reliability is required.

I fail to see why we should start supplying products using a solder which the law makers agree is unreliable. Will they pay for our product failures and our loss of company reputation?

NOW, I hear a rumour that a company in Europe has developed a lead free solder which is approved for the above applications but they are not prepared to sell it to the world at this stage because they want the military contracts. Can anyone confirm this?

Can anyone advise us all on a reliable lead free solder which will not suffer thermal and mechanical fatigue?

Cheers

BigBirdAustralia

I teach soldering using leadfree solder. I only teach repairs, not new boards and no wave soldering.

I have come to only use a tin, silver, copper mix by kestor. Cheaper leadfree solders just do not seem to work as well.

After a thorough cleaning to remove all of the previous solder, I flux and pre-tin both the board and the component with just enough solder to cover and no more. I then reflux the board with a flux pen, place the component and use a hot air tool to bond the component. I will add just a small amount more of solder from a roll containing flux if needed. I use 0.025 diameter solder to do this. With SMT parts their is seldom a need for more solder. If I am using standard resisters and the like with a wire connection then added solder is the norm.

This method has worked well for me. I do use a board holding tool and various stainless tweezers. I also use common "cellophane" tape to hold some components in place while heating them. Even if melted the tape come right off when cool.

I have had no failure using this method. I have had problems from mixing lead and leadfree solders. These may have come from not cleaning good enough

rbeadle

Portland Community College, Microelectronics Technology.

From across the River...

You say that you remove the Pb based solder by thorough cleaning... How in the heck are you going to remove the solder from a PC board, wires, connectors, etc. without heating the heck out of it?? and possibly losing the lands (of a PCB) at the same time?? If you have a method, I would certainly like to hear about it. Solderwick?? That (actually) is my preferred method for non-plated-through holes. For plated through, I use a sucker. Have you got a better idea?? I am curious.

Much Thanks

Bill

Pertaining to the subject of reliability of lead free solder, is there any information about the "TIN WHISKER" problem with lead free solder.

With conventional lead (applications with very small dimentions and requiring very high reliability: military/space) crystilin tin whiskers can grow in any direction and possibly short close conductors/nodes.

Does any one know about this?

We have used lead free solder in production of European product for some time now and had one unexpected problem, we get through soldering iron tips much faster than we used to due to the higher temperatures required.

At one time there was a (Kester ?) product called "Sav-A-Bit" with a high copper content to prevent dissolution of the tips into the solder.

I was under the impression the new lead free solders had the added copper to reduce the melting point as well as preventing dissolution of the soldering tips.

In the UK it was called Save bit and had 1% of added copper. Most soldering iron bits are iron coated to prolong life it is this that is disolved by the new solder. Copper leaches iron when mixed with tin. I notice that the LMP solder that has added silver also reduces bit life. The problems I have seen with the new solder is that it flows much less has a poorer wetting and flow than the leaded solder the fluxes have to be moore agressive and it embrittles when cold. The higher temperatures involved can melt plastics and lead to semiconductor failures. All round a step backwards in our industry. The things that worry me are what if some thing like a power supply or inverter had a critical failure that led to a fire. The fault was in the fail safe circuitry. Who would I sue?

We've had trouble with the flux used with lead free solders because they seem to be slightly conductive. We make small high voltage (5-25kV) low power (µA) fast switching (ps) supplies to use with our own equipment. We had to remake a batch that performed oddly & eventually realised that the flux trapped beneath some of the components was causing the problems. Once the boards were stripped & remade using the same parts but with 'old' type solder everything was ok.

[Perhaps this question would be better in the Civil Engineering section] Has anyone developed lead-free flashing for house roof construction, where slates and tiles meed brick courses? How on earth would one arrange a waterproof joint around a brick chimney without leadwork, and what happens to the fragments of lead flashing that fall from demolished houses, after the lead arrives in landfill?

Why should the electronics community be largely constrained and the construction community less so (rhetorical question)?

Troubling stuff...

Yes there is lead free flashing available. It has a bitumen backing that melts when heated to a medium heat with a hot air gun. I used some 6 years ago and it is still water tight. I got it from my local builders merchants.

I've been in construction for the last 20 years (and then some!), and have always used either alumimium or galvanized sheet steel for flashing. I have REPLACED lead flashing that failed, failure most often due to metal fatigue (constant expansion and contraction of the joint).