41

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.

“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.”

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.

42

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).

43

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.

44

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”)

45

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.

“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:

46

And that was 2008 :person_facepalming:

47

I use a credit card.

That definitely looks impressive.

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

This may be the best solution.

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

48

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?

49

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

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

50

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)

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.