Solder stencil helpl please

led4power · 2018-12-16T17:02:10.000Z

Lexel:

I wrote I discovered many manufactorieries of Chineese flashlights use leaded solder to reflow the LEDs I had the good stuff with 3% silver and good flux for 50€ a 1000g, simply it was not nearly as good as the stuff with lead and 2% silver or copper used before and yes its superior especially in non commercial use like we do - melting about 25°C earlier than lead free especially if you dont own a high tec reflow oven - flows better under the LED covering more area of the pads, doesnt help the lead free conducts better while it covers less area

1.Please name those many manufacturers, and show proof that they use lead solder,

2. I said PB-free is superior for LEDs because of higher thermal conductivity. Your claim about lead free solder not flowing well may be true for some junk boards (without gold plating or dirty) or solder pastes, but with good boards and solder paste there is absolutely no problem and area coverage is the same as with lead solder. 25C higher temp is not problem, all LEDs are designed to handle it.

If lead-free solder is so much problematic as you claim, we wouldn't have smartphones,laptops etc. today, because defect rate would be high with all those 1000pin BGA and other super tiny chips, if lead-free solder doesn't flow well.

Lexel · 2018-12-16T18:51:23.000Z

led4power:

Lexel:

I wrote I discovered many manufactorieries of Chineese flashlights use leaded solder to reflow the LEDs I had the good stuff with 3% silver and good flux for 50€ a 1000g, simply it was not nearly as good as the stuff with lead and 2% silver or copper used before and yes its superior especially in non commercial use like we do - melting about 25°C earlier than lead free especially if you dont own a high tec reflow oven - flows better under the LED covering more area of the pads, doesnt help the lead free conducts better while it covers less area

1.Please name those many manufacturers, and show proof that they use lead solder,

2. I said PB-free is superior for LEDs because of higher thermal conductivity. Your claim about lead free solder not flowing well may be true for some junk boards (without gold plating or dirty) or solder pastes, but with good boards and solder paste there is absolutely no problem and area coverage is the same as with lead solder. 25C higher temp is not problem, all LEDs are designed to handle it.

If lead-free solder is so much problematic as you claim, we wouldn’t have smartphones,laptops etc. today, because defect rate would be high with all those 1000pin BGA and other super tiny chips, if lead-free solder doesn’t flow well.

Too bad I had no pictures made from for example XHP70 LEDs I removed while the tin was in half solid state
both the LED bottom and the MCPCB thermal pad was literally swiss cheese
The thing stripping the LED in a half solid state is simply not going near the 240°C limit of all those LEDs,
but as I wrote on the majority of LEDs I replace in stock chineese lights were with suspicious leaded solder tempererature stripped

or 2 XHPs 35s from a big company which had literally only 5% of the thermal pad with a connection to ther thermal pad, and LEDs went almost instantly blue and overcoocked themself

Its not fair to name here the brands but about 50% of the chineese, also including top end priced ones had 180°C melting solder

So if we talk about waste, if 1 million flashlights with leaded soldered 3535 LEDs get thrown in the household trash does this cover the one car battery get thrown in it or not by weight?
The main reason for ROHS was the waste problem of all those electronic devices not that its a real hazard for humans while using it

In fact the main problem is this electronic trash not getting properly recycled, because its cheaper to send it as used working electronics to India or Africa,
where kids spread hazardous materials all over the place and burn away the insulation to get to the copper
ROHS cant protect from inproper recycled metal of electronic devices in such cases, the other burning things are way more of a problem than a tiny amount of lead

RobertB · 2018-12-16T17:33:02.000Z

LouieAtienza:

Sure, we know how to properly dispose of batteries, but not everyone in the buying public does… so do we worry about .2 grams of lead when eight Li-ion cells get thrown in the trash?

” According to the U.S. government, lithium ion batteries aren’t an environmental hazard. “Lithium Ion batteries are classified by the federal government as non-hazardous waste and are safe for disposal in the normal municipal waste stream,” says Kate Krebs at the National Recycling Coalition. While other types of batteries include toxic metals such as cadmium, the metals in lithium ion batteries - cobalt, copper, nickel and iron - are considered safe for landfills or incinerators (Interestingly enough, lithium ion batteries contain an ionic form of lithium but no lithium metal ”

teacher · 2018-12-16T17:56:35.000Z

LouieAtienza:

In all fairness I think though with all the more dangerous stuff lurking within a flashlight - like the lithium batteries - and the production, including aluminum (aluminium for the EU guys) and its anodizing process, lubricants and coolants used in the CNC machinery and the fuel for the electrical plants that supply the energy for those machines (and they’re not using nuclear in China), the micro amounts of lead in solder in a flashlight in comparison far pales all the other potentially harmful substances and effects of them. This is akin to noticing the speck in someone’s eye when we have a log in our own. Sure, we know how to properly dispose of batteries, but not everyone in the buying public does… so do we worry about .2 grams of lead when eight Li-ion cells get thrown in the trash?

I agree LouieAtienza, well said. :+1:
Common sense is sometimes not a strong suit of the people who make these laws. :person_facepalming:

Tom_Tom · 2018-12-17T04:42:08.000Z

Lexel, I totally agree that traditional lead solders have some superior properties, and are much easier to work with, for the amateur.

Which is where I started here, encouraging amateur hobbyists to stock up on “the good stuff” whilst you still can, and use it.

Once this is taken seriously, demand for leaded solder will dry up, along with availability. Once the USA jumps on the bandwagon, it will be gone.

The early lead-free materials were dreadful.

However things have changed. Study Restriction of Hazardous Substances Directive - Wikipedia and read the last paragraphs, which are cause for optimism.

Nevertheless, the EU bureaucrats, decided to ban it’s use in EEE many years ago, except with specific exemptions. Which are under continuous review, and all expire after 5 years, if not renewed. And new ones are very reluctantly, if ever, granted.

It is the law here, no matter what your personal opinion of it is.

China also has it’s own RoHS regulations.

en.wikipedia.org

China RoHS

China RoHS (Restriction of Hazardous Substances), officially known as Administrative Measure on the Control of Pollution Caused by Electronic Information Products is a Chinese government regulation to control certain materials, including lead. The Ministry of Industry and Information Technology (MIIT) of China is responsible for approval and publication of China's RoHS regulations. "Administration on the Control of Pollution Caused by Electronic Information Products" (ACPEIP or China RoHS I) was...

The concern is nothing to do with poisoning the user, it is what happens when the EEE is disposed of at end of life. Now all WEEE is supposed to be specifically recycled and the materials re-used, but that doesn’t actually happen.

In practice, 70% of the word’s WEEE still ends up in China for processing, and they are fed up with it. Importation of it has been banned for many years, but it is still smuggled in on a massive scale. It is no longer seen as a valuable resource, but as a severe environmental problem. China domestically is also the second largest producer of WEEE, after the USA.

en.wikipedia.org

Electronic waste in China

Electronic waste or e-waste in China refers to electronic products that are no longer usable and are therefore dumped or recycled. China is the world's largest importer and producer of electronic waste with over 70% of all global e-waste ending up in the world's largest dumpsites. An estimated 60–80% of this e-waste is handled through illegal informal recycling processes, without the necessary safety precautions legally required by Chinese government regulations. Processing e-waste in China's dom...

If nothing else, follow this link. A gram here, a gram there, all adds up. Out of sight, out of mind, not my problem, is not an ethical philosophy.

Every UK citizen is estimated to produce 3.3 tonnes of WEEE in a lifetime. All of which has to be disposed of sensibly. Eliminating the lead, and other banned substances, is part of that process.

Just as eliminating it from petrol was. And from paint. That met with great resistance and lobbying from industry at the time, but who would argue for it’s re-introduction today ? (except for vintage car and aeroplane enthusiasts, who can still get Avgas). Likewise installing 3 way catalysts.

And eliminating SO2 from power station exhausts ( remember Waldsterben ? ). Although you are burning the filthiest brown lignite coal now, and even more Russian gas, since Merkel turned off all your clean nuclear stations. Some corruption involved there ? Just a thought, lots of money to be made digging up coal and supplying gas. And “lobbying” works. Nord Stream 2, and Gerhard Schröder’s involvement for example. But I digress.

Currently also seeing the death of Diesel, largely due to blatant lies and cheating by German manufacturers, who have been found out. Don’t be one of those, using leaded solder where it’s not allowed.

https://en.wikipedia.org/wiki/File:WEEE_Man,*Eden_Project*~~*geograph.org.uk*~~\_785381.jpg

Tom_Tom · 2018-12-17T05:17:44.000Z

teacher:

LouieAtienza:

In all fairness I think though with all the more dangerous stuff lurking within a flashlight - like the lithium batteries - and the production, including aluminum (aluminium for the EU guys) and its anodizing process, lubricants and coolants used in the CNC machinery and the fuel for the electrical plants that supply the energy for those machines (and they’re not using nuclear in China), the micro amounts of lead in solder in a flashlight in comparison far pales all the other potentially harmful substances and effects of them. This is akin to noticing the speck in someone’s eye when we have a log in our own. Sure, we know how to properly dispose of batteries, but not everyone in the buying public does… so do we worry about .2 grams of lead when eight Li-ion cells get thrown in the trash?

I agree LouieAtienza, well said. :+1:
Common sense is sometimes not a strong suit of the people who make these laws. :person_facepalming:

I totally disagree. Common sense seems not to be a strong suit of some vocal forum “pundits” who have not the first clue about the subject.

Every industrial process is tightly regulated in the EU, and the US, and disposal/recycling of contaminated materials is a huge part of the work. You can’t just flush stuff down the drain, landfill, or send it up the chimney any-more.

Batteries is a good one, we have an EU directive on that too, which was not just drafted by some Brussels bureaucrat with an Arts degree, but after wide consultation with some very resistant industry specialists.

en.wikipedia.org

Battery Directive

The Directive 2006/66/EC of the European Parliament and of the Council of 6 September 2006 on batteries and accumulators and waste batteries and accumulators and repealing Directive 91/157/EEC, commonly known as the Battery Directive, regulates the manufacture and disposal of batteries in the European Union with the aim of "improving the environmental performance of batteries and accumulators".: 4 Batteries commonly contain hazardous elements such as mercury, cadmium, and lead, which when in...

Lead was even banned in wheel-weights many years ago. Annoying for me, because they were my primary source for casting lead bullets.

Likewise Germany banned it’s use in bullets for a while, but that got repealed after a very unfortunate boar hunting accident, where a copper bullet ricocheted off a tree trunk, instead of expanding, and killed someone.

UK Forestry Commision banned lead-based bullets for stalkers on their land many years ago.

We banned lead from shotgun cartridges used over wetland many years ago, as did the USA. I only use steel for everything now, and it works just fine, but differently.

The idea of shooting 25 or 50 cartridges, each containing an ounce or so of lead shot, maybe also a plastic wad, per person, at my informal shoot (15 to 20 of us), every two weeks, is abhorrent, which is why, after discussion, we all decided to stop using it. Club rule.

This is over land that cattle graze, and are then eaten by humans.

It also puts us on a more level playing field, where those who can afford the best cartridges no longer have an advantage. We all use the same, steel, fibre wad, which we bulk-buy to special order, and save a lot of money.

Tom_Tom · 2018-12-17T05:35:37.000Z

LouieAtienza:

… and the fuel for the electrical plants that supply the energy for those machines (and they’re not using nuclear in China),

Educate yourself.

en.wikipedia.org

Nuclear power in China

China is one of the world's largest producers of nuclear power. The country ranks third in the world both in total nuclear power capacity installed and electricity generated, accounting for around one tenth of global nuclear power generated. As of February 2023, China has 55 plants with 57GW in operation, 22 under construction with 24 GW and more than 70 planned with 88GW. About 5% of electricity in the country is due to nuclear energy. These plants generated 417 TWh of electricity in 2022 Nuc...

“China ranks fourth in the world in total nuclear power capacity installed, and third by nuclear power generated.”

They have a massive nuclear power infrastructure, are in a joint-venture with France to build the UK’s next one, then roll out their own ones here, once they pass our strict certification.

Our select specialist nuclear engineering degree and post-graduate courses also often involve secondment to China and from China, up to 6 months, for students, to mutual benefit and understanding. They know a lot about nuclear engineering, and other hi-tech stuff.

Making cheap torches is not really a mainstay of their economy. The clever engineers work on much more interesting things.

LouieAtienza · 2018-12-17T05:46:16.000Z

Tom Tom:

Making cheap torches is not really a mainstay of their economy. The clever engineers work on much more interesting things.

Exactly. So if flashlights are such a tiny part of their economy, and so few folks are using leaded solder nowadays, it’s use should be insignificant enough when compared to the dangers of Li-ion batteries, and pollutants from the manufacturing process.

Tom Tom:

“China ranks fourth in the world in total nuclear power capacity installed, and third by nuclear power generated.”

Educate yourself. Before making crude remarks and bogus Wiki references.

*_80_* of China’s energy consumption come from coal and crude oil. As massive as their nuclear infrastructure is, it, along with hydro and wind, combine for only 13 of China’s energy consumption.

Statista

China: energy consumption breakdown by source | Statista

In 2020, coal accounted for 56.8 percent of total energy consumption in China.

teacher · 2018-12-17T18:08:27.000Z

Tom Tom:

teacher:

LouieAtienza:

In all fairness I think though with all the more dangerous stuff lurking within a flashlight - like the lithium batteries - and the production, including aluminum (aluminium for the EU guys) and its anodizing process, lubricants and coolants used in the CNC machinery and the fuel for the electrical plants that supply the energy for those machines (and they’re not using nuclear in China), the micro amounts of lead in solder in a flashlight in comparison far pales all the other potentially harmful substances and effects of them. This is akin to noticing the speck in someone’s eye when we have a log in our own. Sure, we know how to properly dispose of batteries, but not everyone in the buying public does… so do we worry about .2 grams of lead when eight Li-ion cells get thrown in the trash?

I agree LouieAtienza, well said. :+1:
Common sense is sometimes not a strong suit of the people who make these laws. :person_facepalming:

I totally disagree. Common sense seems not to be a strong suit of some vocal forum “pundits” who have not the first clue about the subject.

Every industrial process is tightly regulated in the EU, and the US, and disposal/recycling of contaminated materials is a huge part of the work. You can’t just flush stuff down the drain, landfill, or send it up the chimney any-more.

Batteries is a good one, we have an EU directive on that too, which was not just drafted by some Brussels bureaucrat with an Arts degree, but after wide consultation with some very resistant industry specialists.

Battery Directive - Wikipedia

Lead was even banned in wheel-weights many years ago. Annoying for me, because they were my primary source for casting lead bullets.

Likewise Germany banned it’s use in bullets for a while, but that got repealed after a very unfortunate boar hunting accident, where a copper bullet ricocheted off a tree trunk, instead of expanding, and killed someone.

UK Forestry Commision banned lead-based bullets for stalkers on their land many years ago.

We banned lead from shotgun cartridges used over wetland many years ago, as did the USA. I only use steel for everything now, and it works just fine, but differently.

The idea of shooting 25 or 50 cartridges, each containing an ounce or so of lead shot, maybe also a plastic wad, per person, at my informal shoot (15 to 20 of us), every two weeks, is abhorrent, which is why, after discussion, we all decided to stop using it. Club rule.

This is over land that cattle graze, and are then eaten by humans.

It also puts us on a more level playing field, where those who can afford the best cartridges no longer have an advantage. We all use the same, steel, fibre wad, which we bulk-buy to special order, and save a lot of money.

Exactly… the things you mention are great examples where “common sense” was actually used.

Banning lead solder use in a flashlight is completely devoid of “common sense”…. as far as I am concerned.

Agreed…‘Common sense’ certainly does seems not to be a strong suit of some vocal “forum ”pundits” “. Some even grossly overestimate the true value of their commentaries.

.
edit for spelling correction.

CRX · 2018-12-17T18:03:18.000Z

True

Tom_Tom · 2018-12-18T00:27:10.000Z

LouieAtienza:

Educate yourself. Before making crude remarks and bogus Wiki references.

*_80_* of China’s energy consumption come from coal and crude oil. As massive as their nuclear infrastructure is, it, along with hydro and wind, combine for only 13 of China’s energy consumption.

China: energy consumption breakdown by source | Statista

Again I remind you that you are the one who said “(and they’re not using nuclear in China)”. Which couldn’t be further from the truth. So I politely corrected you. But now you seem determined to turn this into some sort of China bashing rant, but you can’t even get your facts right, and just won’t let it lie.

China is little different from the USA, which also uses fossil fuel for nearly 80% of it’s energy production.

Here is a reference that is anything but “bogus”:

https://www.eia.gov/energyexplained/?page=us_energy_home

“The three major fossil fuels—petroleum, natural gas, and coal—combined accounted for about 77.6% of the U.S. primary energy production in 2017:
Natural gas—31.8%
Petroleum (crude oil and natural gas plant liquids)—28.0%
Coal—17.8%
Renewable energy—12.7%
Nuclear electric power—9.6%”

The USA hasn’t built a new nuclear station for 30 years, apart from two AP1000s under construction (another two have already been abandoned), but their manufacturer Westinghouse has filed for bankruptcy, their completion is uncertain, and it has recently reneged on it’s plans to build three more in the UK (Moorside Cumbria), to huge embarrassment. Civil nuclear in the USA is not in good shape, and your existing stations are getting old.

en.wikipedia.org

AP1000

The AP1000 is a nuclear power plant designed and sold by Westinghouse Electric Company. The plant is a pressurized water reactor with improved use of passive nuclear safety and many design features intended to lower its capital cost and improve its economics. The design traces its history to the System 80 design, which was produced in various locations around the world. Further development of the System 80 initially led to the AP600 concept, with a smaller 600 to 700 MWe output, but this saw l...

“Two AP1000 reactors are being built in the United States at Vogtle (Units 3 & 4)[47]. Two units were also being constructed at VC Summer (Units 2 & 3)[48], but construction was abandoned in July 2017 (4 years after starting construction) due to Westinghouse’s recent bankruptcy, major cost overruns, significant delays, and other issues.[49] Although the project’s primary shareholder (SCANA) had determined that completing Unit 2 while only abandoning Unit 3 was a financially feasible and internally favored alternative to abandoning the entire project, this was dependent on their minority shareholder (Santee Cooper) agreeing. Due to Santee Cooper’s board voted to cease all construction and SCANA’s inability to find another shareholder to take Santee Cooper’s place, SCANA was forced to revert to abandoning the entire project.

All four reactors were identical and the two projects ran in parallel, with the first two reactors (Vogtle 3 and Summer 2) planned to be commissioned in 2019 and the remaining two (Vogtle 4 and Summer 3) in 2020.[50][51] After Westinghouse filed for bankruptcy protection on March 29, 2017 the construction has stalled.”

Whereas:

“In 2012, China had 15 nuclear power units with a total electric capacity of 11 GW and total output of 54.8 billion kWh, accounting for 1.9% country’s total electricity output. This rose to 17 reactors in 2013. By 2016 the number of operating nuclear reactors was 32 with 22 under construction and other dozen to start construction this year. There are plans to increase nuclear power capacity and nuclear power percentage, bringing the total electricity output to 86 GW and 4% respectively by 2020.[48] Plans are to increase this to 200 GWe by 2030, and 400 GWe by 2050. China has set an end-of-the-Century goal 1500GWs of nuclear energy, most of this from fast reactors. China has 32[49] reactors under construction, the highest number in the world.”

en.wikipedia.org

Energy policy of China

China is both the world's largest energy consumer and the largest industrial country, and ensuring adequate energy supply to sustain economic growth has been a core concern of the Chinese Government since the founding of the People's Republic of China in 1949. Since the country's industrialization in the 1960s, China is currently the world's largest emitter of greenhouse gases, and coal in China is a major cause of global warming. However, from 2010 to 2015 China reduced energy consumption Bei...

Now, please can we return to solder stencils, their use, and the selection of materials to use with them, in accordance with the letter and spirit of the laws applying in the regions where they are to be used.

Tom_Tom · 2018-12-18T00:59:10.000Z

teacher:

Banning lead solder use in a flashlight is completely devoid of “common sense”…. as far as I am concerned.

What seems like “common sense” to one person, may seem like nonsense to another person, perhaps more clued up on the wider picture.

The legislation exists for good reasons, it wasn’t just dreamed up as a “bright idea” one day, industry was consulted and has responded, even found new materials to be superior, it is the norm nowadays (as well as the law).

Back to my first point: you can still buy leaded solder, for now, and use it as an amateur hobbyist, or to repair pre-2006 stuff. But if you manufacture things for sale, no matter how small your business, it is illegal to use it (except under certain precisely defined exemptions, which are mostly expected to be withdrawn within 5 years or so, as industry develops improved compliant processes).

LouieAtienza · 2018-12-18T04:05:30.000Z

Tom Tom:

Again I remind you that you are the one who said “(and they’re not using nuclear in China)”. Which couldn’t be further from the truth. So I politely corrected you. But now you seem determined to turn this into some sort of China bashing rant, but you can’t even get your facts right, and just won’t let it lie.

I’m not big on emojis, but I thought I was pretty clear that I was being facetious with that comment. Telling someone to “educate themselves” is far from being polite; it implies that person is somehow uneducated. Alas meanings get lost when we cannot determine facial expressions or hand gestures (context). I agree whole-heartedly that we should be good stewards of the earth; I just felt you made it seem like China is one of the bastions of environmental care, when it ranks among the top 13 countries with the most polluted urban areas. (The US by the way ranks in the top 12 least polluted urban areas.) Being from the US I defend my country so I hope you understand my objection to others who “scold” us online about pollution when we’re not even close to the largest perpetrators.

Back to the topic on hand… A while back I attempted to make stencils for some prototype circuit boards I made - by actually milling out blank PCBs on my CNC. I wasn’t as successful milling a stencil, but I did find “cutting” the solder paste down (with whatever flux I had on-hand at the time) a tad helped achieve better results. Then again, the solder “pads” were a lot larger than those used on flashlight PCBs. I also did this with a CNC router which wasn’t the tightest tolerance machine, though a couple years ago I built a CNC mill with ground ballscrews and a metalworking electric spindle that probably would give far more accurate results.

Tally-ho · 2018-12-18T05:57:49.000Z

LouieAtienza:

I just felt you made it seem like China is one of the bastions of environmental care, when it ranks among the top 13 countries with the most polluted urban areas. (The US by the way ranks in the top 12 least polluted urban areas.) Being from the US I defend my country

Defending your country is fine as long as you are not partial but remain realistic.
This are just ranks for global pollution by country, now rank them by “pollution by inhabitant (per capita)” and again by “pollution by quantity of products consumed (per capita)”.
Many countries choosed to delocalize their production to china, by doing so they also delocalized their pollution to china, this is called externalization (well, in french it is called “externalisation”). They are not polluting their country for their own goods only.
How much do we consume goods “made in our own country” and goods “made in china or elsewhere” ?

To put things into perspective:
(NB : because “how much are we consuming” gives a better idea of “how much are we polluting”)

Tom_Tom · 2018-12-18T10:37:28.000Z

China is trying hard to clean up, and has made huge strides in the past few years. But it is also the world’s major supplier of stuff, and recycler of 70% of the World’s waste from the resulting WEEE, i.e. a dustbin twice over. Easy to criticise standards, but basically most of that pollution is off-shored from the nations who are happy to let China do their dirty work for them, and enjoy the low cost labour. Then harangue them for being competitive, complain about the imbalance of trade (They are basically giving you this stuff for free, in exchange for you racking up debt in your currency. Your decision to accept it, maybe you could try walking away (no) or jack up interest rates and inflation to try to make it go away), then try to wriggle out of the debts stacked up over the years to keep things looking rosy for the dumb and happy home audience, and also issue sanctions, tariffs etc. to play to the crowd (mid term elections etc.)

But this is changing rapidly. Give it another ten years say, and the situation will be unrecognisable from today.

China is also the world’s largest producer of renewable energy, hydro, solar, wind etc. and has big plans to increase this.

en.wikipedia.org

Renewable energy in China

China is the world's leader in electricity production from renewable energy sources, with over triple the generation of the second-ranking country, the United States. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity, and is expected to contribute 43 per cent of global renewable capacity growth. China's total renewable energy capacity exceeded 1,000 GW in 2021, accounting for 43.5 per cent of the country's total power generation capacity, 10.

“In 2017, renewable energy comprised 36.6% of China’s total installed electric power capacity, and 26.4% of total power generation, the vast majority from hydroelectric sources.”

The cleanest countries are also the wealthiest, unsurprisingly. We can afford to be, whilst metaphorically sweeping the dirt under the carpet…

Back on topic, a quick search for e.g. “etching a solder stencil” will give many hits describing how to make your own high quality ones, with domestic materials.

E.g. the first hit I got at DIY home-made SMT metal stencil - the definitive tutorial - YouTube which seems informative.

And a tutorial on how to use one:

https://www.sparkfun.com/tutorials/58

It’s not what I’m used to in professional work, but it shows that it doesn’t have to be a mysterious skill / black art or require any expensive tools or expenditure on materials.

Good enough for printing simple drivers and MCPCBs.

Not so good for serious work on bigger pieces, where tight design, knowledge, training, experience, ongoing research and development, trusted suppliers of consistent high quality materials, equipment and materials selection, supply chain management, environmental control, management of shelf-life, maintenance, and process control are all required to achieve e.g. the standards necessary to manufacture, say, an iPhone. And when a toaster oven or hotplate or cheap rip-off soldering iron is not usually a suitable tool.

I’m more used to seeing full automation, from stencilling to pick and place to reflow, quickly, in multi stage ramps in inert atmosphere, supplied from big Linde cryogenic nitrogen tanks. Then to automated optical inspection and electrical test (very very thorough). And cleaning processes (no, we do not believe in “no-clean” solders)

See e.g. Stencil printing - Wikipedia to learn just a little of the complexities once you make bigger things, and why manufacturing engineering is an important, difficult discipline, and the good ones are worth their (very decent) salaries or consultancy fees, particularly if a company has hit a problem, and their staff don’t know how to fix it, and absolutely needs someone to come in and show a way forward, using what they have got. Quickly.

The creative design bit (my strength) is relatively easy, but I take the trouble to learn from production about their challenges, and help, and re-design where possible.

Chinese £50 PC motherboards for example. How do you think that they are designed, and manufactured, distributed and are generally reliable. With all their thousands of connections. Magic fairies or wishful thinking didn’t do that, it takes serious engineering and manufacturing skills. Far far harder than cobbling together a torch driver.

Meanwhile the West slides further into decadence and continues to lose it’s vital industrial base, and much knowledge of future importance. I can’t really complain, the UK invented the Industrial Revolution, and painted the world map red, with our empire, where the Sun never set. But that was a long time ago, and where are we now ? (please don’t try to answer that one at the moment). Still the World’s 5th largest economy, not bad for a tiny island with a tiny population and few raw materials left (we extracted most of them up long ago).

We survive because of our skills, intellect, education, clear thinking, universal language and historical ties and contacts, moderate politicians and civil servants who just want to do the best for the country.

Except that is all in chaos at the moment, and it is very difficult to identify any good people any more, just utterly venal and hypocritical, frankly very poor intellectually or socially, specimens. Quite a few just obviously corrupt, many with a long history of it. Not even attempting to hide it. Not just here, but EU-wide.

And a few pockets of extreme excellence, and a few individuals, unsurpassed, just not widely known outside their industries, but valued and respected worldwide.

I’m not going to take a pop at USA politics, because that never ends well here, and I no longer think that we are any better than you. I’ll just say that all empires decline and fall. And the USA has barely even had an empire, nor any clue how to administrate it wisely. Whereas China has had many. And plays the long game.

Read U.S. Trade Deficit With China and Why It's So High

“Current Trade Deficit
As of July 2018, the United States exported a total of $74.3 billion in goods to China. It imported $296.8 billion, according to the U.S. Census Bureau. As a result, the total trade deficit with China is $222.6 billion.”

I’t’s laughable. The USA’s second biggest export to China was soybeans. $12 billion (after commercial aircraft $16 billion) Until Mr. T went random and did what he did. Instantly China stopped buying USA soybeans, they can get them elsewhere, possibly cheaper, they used to offset the balance of payments deficit. How did that help the USA soybean farmers, or benefit the USA economy and trade deficit ?

Nevermind imposing excessive tariffs on e.g. steel, that is not available from local suppliers at world prices, because they are simply not competitive. Meanwhile USA users of steel have to pay the extra price, and are themselves forced out and destroyed by more efficient competition.

You can’t even build and run a civil nuclear power station any more, you’ve forgotten how to do it safely, afford-ably, and to schedule, after over 30 years of lazing around and letting the skills die out, with the old men who still could.

Protectionism just does not work. Free trade does.

And here is more food for thought:

PubMed Central (PMC)

Our United States legacy: lessons learned from the British Empire

eas · 2018-12-26T06:11:30.000Z

Tom Tom:

Our United States legacy: lessons learned from the British Empire - PMC

And that was 2008 :person_facepalming:

Lumencraft-Matt · 2018-12-27T23:31:18.000Z

eas:

How are you forcing the paste through the stencil and clearing away the excess?

I use a credit card.

calipsoii:

Always had good luck with the standard SS stencils from OSHStencils using the included credit card scraper.

I hold the scraper at a 45 degree angle and press hard just before the edge, forming a convex shape. That way the paste is first squished into the hole by the convex shape of the card, then the excess scraped away by the sharp trailing edge.

I keep the solder paste in the fridge, then let it warm up for an hour before using it. When reflowing, I follow the recommended reflow profile, letting the board soak at 150F for 60 seconds so that the flux can do it’s work, before ramping the heat for a quick reflow.

That definitely looks impressive.

Tom Tom:

Solder paste has a shelf life. It keeps much longer in the fridge, first thing would be to try some fresh stuff.

I think I probly do need to store it in the fridge. Some batches I’ve had were here several months.

Tom Tom:

Or find an experienced contract assembler who could do this for you.

This may be the best solution.

Lexel:

if you notice your paste getting a bit to dry and its in the scringe type cut the end push all to a pot and add a tiny bit of isoprpanol or ethanol
its usually adding only a few mg alcohol per gram paste to soften it up again

I was wondering what could be used on dry paste. I will experiment with this also.

Lumencraft-Matt · 2019-10-12T14:16:39.000Z

Hi all,

I have another small problem I could use your help with. The company that makes my mcpcbs sent me a file for making the solder stencil. It is a .rar file and OSH park cant use that type of file. There used to be an online converter that would change it from .rar to .gtp for me but that no longer exists.

My question is what software do you guys recommend for editing this type of file? I need to export it as something I can load to osh, but also I would like to be able to reduce the size of the LED pads by 10-15% as suggested by Mark from Cutter electronics in another thread.

What are my options?

WTF · 2019-10-12T16:49:04.000Z

.rar should be a compressed package, similar to zip.

Try unpacking it with a file opener compatible with rar, like winzip.

KnHawke · 2019-10-13T02:49:33.000Z

Just need to toss in my two cents in this:
With the stencils, the one supplier my company works with can go as thin as 4 mils (maybe more, we haven’t checked), standard is 5.
If there is too much solder paste still occurring, the best way to counter is the design of the stencil cutouts themselves. For example, the DTP pad in the center of most High Powered LEDs, instead of one large cutout for it, seen pads like that with about 6 partial cutouts for example. So when the solder is flowed through the Oven, it spreads and pulls the component down. Same should be applied to the adjoining electrical contact pads so there will be minimal bubbling in between the surfaces (You can only truly seen them via an X-Ray device)
Another way that I have seen done is, with an SOIC8 for example, is to have cutouts on either end of where the component foot lands, allowing solder to flow up the leg and over the foot.

and lastly:
For the love of god…. DO NOT use an alcohol to thin out or re-wet the paste itself, it will cause the exact opposite of what you are trying to achieve!
If you need to, just use Paste Flux, a off-white fluid type. The pure liquid type evaporates way too fast to be of much use after it is mixed in.
(BTW, we use ALOT of Alpha Solder Paste every day, and we sometimes use the Paste Flux to thin the mix or just reflow parts that are too much of a pain to put back in my hand, like QFP144s, QFNs or BGAs)

vestureofblood:

Hi all,

I have another small problem I could use your help with. The company that makes my mcpcbs sent me a file for making the solder stencil. It is a .rar file and OSH park cant use that type of file. There used to be an online converter that would change it from .rar to .gtp for me but that no longer exists.

My question is what software do you guys recommend for editing this type of file? I need to export it as something I can load to osh, but also I would like to be able to reduce the size of the LED pads by 10-15% as suggested by Mark from Cutter electronics in another thread.

What are my options?

Like what WTF has said, ya need to repack it from WinRAR format to WinZIP.
As to editing the files, you need a Gerber Editor. I have not looked for those but they may cost you for a decent one, but you can find viewers all over the place.