What Did You Do Today 2021

Today I took delivery of a 500 gram reel of "proper" 60/40, 1.2mm cored solder. Its for use on PCB's and I don't know if it's me or my soldering irons, but I just cannot get on with the crappy lead free stuff. It looks like it may get some use straight away as this week, one of my laptops has a non working screen and yesterday my disability scooter refused to go. This might get expensive.

Anthony, if you've had your irons for some time, you will need to replace them. The lead-free solder melts at 34 degrees higher temperature, and older iron may not get there. Especially a problem if you are soldering parts that conduct a significant amount of the heat away.

The lead-free solder also doesn't freeze with the nice shiny surface that suggested a good joint had been made using the lead-tin solder.

Bill

You're not the only one! It keeps the electronics repair people in business, however, being responsible for far more solder joint failures, and other problems, than 'proper' stuff. Rather than tooling up to try to use the 'orrible stuff, stick with Pb-containing solder, and buy a lifetime's supply, while you still can.

Useful tip, should anyone need to de-solder a Pb-free joint, say to remove a failed component on a (modern) pcb. Add Pb-containing solder to the joint before sucking or wicking. It will increase the solder's fluidity and lower its melting point. May need to do it more than once. And if you're a masochist, hand-soldering SMDs, I think Pb-containing solder is the only way to go.

That's why I've just bought a 500 gram reel. I did get it from a UK supplier, but it's labelled "Made in Taiwan", so it looks like another product we don't make any more.

Quite amusing, there's a moan in one of my 1940's A5 sized Model Engineering magazines that proper tin solder was replaced by 60:40 rubbish as a war economy, and the cheapskates never fixed it.

In practice, the alleged unreliability of tin solder joints seems greatly exaggerated. Going back 20 years, much concern was expressed that lead free solder would increase the problem, but at that time there was no understanding of what caused whiskers to form and it was assumed lead in solder reduced the effect. Later research suggests lead-free solder is innocent, or at least much less whisker forming than feared.

My life is full of electronics, and - so far - I've never seen a failure caused by growing tin whiskers. Dry joints, electrolytic capacitors, corrosion damage, resistors changing value, static electricity, water, tired fuses, insulation damage, cracked tracks, tracks lifting off the board, yes. I'm not saying tin whiskers don't exist, or that high reliability electronics can't use lead, but lead leaching out of landfill into the water supply is a serious problem. Irresponsibly dangerous. Not because hobbyists use a bit of 60:40 solder, but because industry make billions of electronic boards every year. In 2000, about 80000 tons of lead solder per year. Anthony's 500g reel isn't the problem, it's the other 160 million!

And Anthony needs a new soldering iron. Tin solder is difficult to use if the iron isn't hot enough. So is 60:40!

Dave

Edited By SillyOldDuffer on 17/07/2021 11:27:09

Dave you mention that the problem with lead is that it leaches out of landfill into the water supply, I was under the impression that current landfill sites had to be located such that there could be no contamination of water supplies to the extent that a number of recent landfill sites have been constructed with a non-porous membrane as a foundation expressly to protect from contamination of water supplies. The mind boggles at what sort of nasties could be dissolved in our drinking water. Dave W

Dave, I have suffered the problem of tin whiskers. The OC170/171 transistors can have this problem.

The whiskers grow internaly and can produce shorts between the four connection wires.

One remedy is to mechanically shock the case to fracture the whiskers or another way is to fuse the whiskers.

I ordered some replacement transistors and these had already whiskers!

John

I've been cutting some Iroko wood to turn some pulleys for the 1896 Ford model that I am making.

Not for nothing is it known as ironwood. It's very hard.

I'don't use much wood but when I do I go to Nottingham Hardwood Timber who supply small pieces for pencil makers, model makers, furniture makers and even boat builders.

**LINK**

http://www.nottinghamhardwoodtimber.co.uk/wood-turning-self-select-timber-store/

I have absolutely no connection with this (largely one-man) business other than as a very satsfied customer.

Brian

Gosh - how old might an OC170 be? This Philips spec is dated April 1958. No wonder the poor things have grown whiskers, ho ho!

This picture (pinched from VMARS, July 2008) shows whiskers inside a transistor:

Note the two short whiskers are growing from the can towards the lead; the phenomenon seems to be more associated with smooth tinplated surfaces rather than solder joints.

A transistor of this age would have been soldered with 60:40, not high tin.

If whiskers were a major problem I'd expect a high failure rate with SMD boards - the inter-pin gap of chips on these look less than 0.2mm and there are thousands of them in a laptop. So far so good, but I wouldn't bet the farm on it. Maybe they will all fail over the next 20 years!

Talking of whiskers, I've never grown a beard or moustache. Is that a record?

Dave

Whilst lack of facial hair is unfashionable at the moment it not a record no never have had any. I believe its common among the majority of people.

Are we excluding the fairer sex, quite a few have have significant facial hair!

Robert Butler

Mmm, not true....Iroko is also known as African Teak or Nigerian Teak, definitely not Ironwood - in fact, there is no such thing as Ironwood, or an Ironwood tree...Poor usage of the term has resulted in any wood heavier than water being termed Ironwood, but there is no botanical wood named such. Iroko is native to the North African West coast and only resembles Teak - it is not Teak...

And, Iroko floats on water..

Dad was a Master Cabinet Maker, so I have saw dust in my Blood..

Joe

Today I got this far with my power feed conversion:

A simple problem solved and all is good. Power hungry devices mounted on a nice square yard's worth of aluminium heat sink.

Going back to the discussion about solder, I'm surprised our resident internet expert didn't dig this out.

I was changing a lot of optics. By some miracle I always seemed to guess correctly as to whether it was the photodiode or the LED that had failed.

Then I realised I wasn't changing the optic, I was changing the solder and always at the button cell end.

One leaky battery and the solder joint died. Still looked okay it just didn't conduct

Iroko, also known as poor man's teak. The dust from this timber is an irritant , it's like pepper, catches in the throat and induces coughing.

MASK UP !!

Just a caution here, many years ago my brother was severley ill with a massive allergic reaction after making a nest of Iroco coffee tables, admittedly in a less than desirable environment. He was VERY ill, and never had anything similar before or since when working with other timbers. Apparently the dust from sanding is a know bad allergen.

Just thought it would be worth a mention.

Take care. Mike

Back in the workshop today after a week or so waiting for various deliveries of goodies for the electronic lead screw project to arrive. I haven't been idle in the interim, though. I've been sorting out the Gcode for the panels to fit on the metal enclosure which will contain the electronic wizardry.

Today, after a tentative trial with some old Perspex off-cuts, I did the engraving of the legends for the two panels, then changed to an end mill to cut out the holes. First one went OK, but I soon realised that the second wouldn't fit on the A5 piece of black Perspex that I'd bought. A quick re-do of the design to narrow it down by 10mm (luckily the engraving could stay in the same relative position) and we're off and running. Well, tomorrow I will be running the cutting out program.

Here's what the engraving looks like, still with its whiskers on. I'm hoping that the letters will be sufficiently readable without resorting to filling in with paint.

Sorry about the reflection of yours truly - I didn't realise it was there 'til now!

And then after the panel cut-outs were machined.

You can just see, top left, where the counterbore has been started, indicating that the panel won't fit as is.

As an aside, the trial run with an engraving tool on a piece of off-cut Perspex showed that the workpiece wasn't quite flat, so I prepared the sacrificial MDF board by facing it off first with a ¼" end mill and securing the Perspex to it with double-sided "jelly" tape. By golly, that stuff sticks like you-know-what to a blanket!

Anyone have any ideas how best to remove the engraving whiskers without damage to the surrounding surface?

John

I’ve heard iroko called a lot of names,usually with an expletive attached,but never ironwood. Apart from the dust,which can be evil,it’s notoriously unstable-rip a straight piece and you may finish up with two banana- shaped ones.

There’s another African timber called Ekki or Red Ironwood (Lophira alata). Now that’s really hard and very heavy

Iroko is just one of the woods that can cause problems Yew is not good for you either. There are many more some will effect people quite badly and others to a lesser extent.

This is why I wear a fully enclosed positive pressure face shield which has battery power pack and filters it is also impact resistance