Help me shop for an ultrasonic cleaner?

[cvanc]

Hi gang-

So what's the good way to go if I want an ultrasonic cleaner?  Are any of the low cost (i.e., eBay or AliExpress) providers trustworthy?

I'm looking to clean populated PC boards mostly, but sometimes other things.  I've done some reading and it seems I should be looking for a variable frequency unit, are they really that much better?

Thanks...

[georges80]

I've had a cheap no-name ebay unit for quite a few years now. Works just fine and continues to work. Cleans boards very well then I just use compressed air (compressor) to blow dry. With an ebay unit you don't need to worry that it'll be so powerful as to remove components off the board

Just pick one large enough to take whatever you need to clean.

Can't see the point in spending any extra $ for something fancier.

cheers,
george.

[DaJMasta]

Large enough, then variable frequency, that covers a lot of your bases.  I went effectively an ebay route, but with an actual brand name attached and got a Trusonik branded unit (though I think it was cheapest direct from the company).  Somewhat loud, and I don't have a lot of hours on it, but it's been working well enough with just water and Alconox.

For the noise, it helps to have it on something with some vibration isolation, then I put a small silicone sealant bead around the bottom of the lid (not gluing it down, just dried on the lid), and put some split silicone tubing on the bottom wire bits of the rack to minimize noise and it makes a big difference, though it's still not silent.  The split tubing goes a little soft in the heat of the chamber, so it can fall off, but it's worked pretty well so far.

[Gandalf_Sr]

I got one like this one.

What do you guys use for cleaning fluid?

[metrologist]

I got inexpensive from ebay, one that is an all stainless cube. I like it! I can set the time and temp, but not variable frequency. My understanding is that variable frequency is nice to avoid nodes or "hot/cold" spots... You can achieve the same thing by moving the parts around.

[salvagedcircuitry]

I started with a ~200w 10 Liter ultrasonic. It was made by a company called prosonix. They no longer exist. I paid $300 for it. I've had it for close to 8 years now and it worked great for 4 of those years until the timer failed. Then the transducers gradually stopped working.
I took it apart and found out that it was a very cheap rebadged chinese unit  . This is the closest resemblance to my unit:
https://www.ebay.com/itm/162246817237

It turned out the unit was run by old school metal caned to-3 packaged transistors. Unfortunately, the numbers were rubbed off on the transducers. I tried repairing it with other transducers but they simply don't sell new genuine to-3 transistors of the right specifications to match the unit.
What surprised me is how simple my ultrasonic machine was. It used an off-the-shelf Winco stainless-steel food tray as the tank, and the food tray lid as the lid. The basket was a unit-specific folded sheet aluminum basket. The transducer boards were clearly repurposed general transducer boards like these https://www.ebay.com/itm/372237002078 stacked and screwed to the bottom of the unit.

There are dozens of other companies who rebadge these chinese units as well. They will look remarkably similar.

Regardless, the unit served me well for cleaning engine carburetors, and it worked ok for cleaning circuit boards. The unit is quite loud though, and I have major doubts that it is truly operating at 35Khz. if you get a cheap chinese ultrasonic, leave it in a different room when operating.

In terms of solution, I originally started experimenting with various de-greasers + distilled water, but that would often not clean off flux residue. From my research, it still looks like the best suitable PCB solution is Branson EC + distilled water. However, I have not found any literature on how to properly dispose of Branson EC. Considering it is a hazmat-class chemical DO NOT POUR IT DOWN YOUR DRAIN. If you go this route, look up how to properly dispose of such a chemical in your area.

Some general pointers on ultrasonic machine operation:
-Don't ever run the machine without solution. This can crack the transducers. I purchased a used crest and the damage was pretty bad, likely from this reason.
-Fill up your tank to the level designated by the manufacturer. Mine was about an inch from the top, the part where there was a sheet metal bend. Improper solution levels can damage transducers.
-Avoid placing items directly on the tank bottom, especially heavy items. 
-Don't move the object in the ultrasonic machine when the machine is operating.
-Most companies suggest not to put your hand in the machine while operating.

Some of the bigger names in ultrasonic machines are Branson, Sonicor and Crest. They seem to make decent units and have a bunch of literature on the subject of ultrasonic cleaning.
If you really want to go all in, research vapor degreasers 

[orion242]

I have this unit and run it 15-30min a week since I got it.

https://www.eevblog.com/forum/reviews/chinese-ultrasonic-cleaner-10-l-liter/msg512923/#msg512923

I tried alconox for a while and it did a good job.  When I compared results with Branson EC, I was sold on the Branson.  I dump it straight down the drain, right / wrong...I only change it maybe once a quarter when it looks really nasty.  With the recommended concentration, 5min @ 60C will remove any fresh flux completely even under large SMD packages.  If its something from the 60s with hard crystallized flux, it going to take a few more minutes.  Severe water damage crusties, even longer.

I don't notice any uneven cleaning in my unit even as a fixed freq cleaner.  I do normally flip board half way thru.  Wouldn't shell out for swep frequency unless your doing a large volume and cannot be bothered to just stir things up half way thru and dealing with really nasty boards.  Even on batches I don't mix up, its rare to see certain areas that didn't come clean as long as its not 30yr old flux or extreme water damage.

I mix the Branson with tap water, and when they come out wash them off with stupid hot tap water then blow them completely dry with shop air.  80psi and nearly endless supply. Leave the 100F+ board for 15min after that and its dry as.
 
IPA, you must be nuts IMO.  Its a fire hazard and its going to evaporate really quick at the normal cleaning temps which I assume will make consistent results a $hit show.  Not cheap either with 10L unit requiring even more frequent changes.

Far as the noise, does anyone expect shoving >100W of sound energy into something results in a whisper silent device?!?

[salvagedcircuitry]

I have this unit and run it 15-30min a week since I got it.

https://www.eevblog.com/forum/reviews/chinese-ultrasonic-cleaner-10-l-liter/msg512923/#msg512923

I tried alconox for a while and it did a good job.  When I compared results with Branson ES, I was sold on the Branson.  I dump it straight down the drain, right / wrong...I only change it maybe once a quarter when it looks really nasty.  With the recommended concentration, 5min @ 60C will remove any fresh flux completely even under large SMD packages.  If its something from the 60s with hard crystallized flux, it going to take a few more minutes.  Severe water damage crusties, even longer.

I don't notice any uneven cleaning in my unit even as a fixed freq cleaner.  I do normally flip board half way thru.  Wouldn't shell out for swep frequency unless your doing a large volume and cannot be bothered to just stir things up half way thru and dealing with really nasty boards.  Even on batches I don't mix up, its rare to see certain areas that didn't come clean as long as its not 30yr old flux or extreme water damage.

I mix the Branson with tap water, and when they come out wash them off with stupid hot tap water then blow them completely dry with shop air.  80psi and nearly endless supply. Leave the 100F+ board for 15min after that and its dry as.
 
IPA, you must be nuts IMO.  Its a fire hazard and its going to evaporate really quick at the normal cleaning temps which I assume will make consistent results a $hit show.  Not cheap either with 10L unit requiring even more frequent changes.

Far as the noise, does anyone expect shoving >100W of sound energy into something results in a whisper silent device?!?

Something not as well known as it should be: You can ultrasonically clean items within glass containers within solution. As in use a beaker tray, insert a glass beaker, put a specific solution in the beaker and insert pcb. Then leave the remainder of the tank as just normal water. There's a whole guide about ultrasonically cleaning with beakers in this branson cleaning manual. Page 23:
https://www.nist.gov/sites/default/files/documents/ncnr/Branson-1510-DTH-Ultrasonic-Cleaner-Manual.pdf
This way you don't waste a lot of chemical on a small board. Also, I would highly suggest switching over to distilled water to prevent unwanted oxidation of pads when cleaning.

[metrologist]

Thanks for all the tips everyone, especially using beakers!!!

Some general pointers on ultrasonic machine operation:
-Don't move the object in the ultrasonic machine when the machine is operating.

Why would that be? I was thinking of rigging a lazy-suzan kind of hanging tray and have it motorized!

[salvagedcircuitry]

I believe it has something to do with destructive interference with the resulting waves from the transducers, but I am not sure if that is the whole story. I noticed this info in every published source of ultrasonic cleaning I can find. That includes literature from Crest, branson and sonicor. I'm sure you could send the question their way and they may give you more of an explanation.

[orion242]

Also, I would highly suggest switching over to distilled water to prevent unwanted oxidation of pads when cleaning.

I'll give that a try.  I work with boards that at minimum take up half the basket.  Largest just fit in horizontal.  The smaller ones I can stack vertical and pack them in.  Too dense, I see issues requiring reruns.  I notice a very light frosting on things, but its very minor assuming its only 5 minutes and I dry them right after.  Usually nothing I can't solder right back on it I need to.   Frankly maybe its the lead free, but brand new PCBs look to have nearly the same corrosion.  They certainly have more residue overall than what I end with.   For the rate I change it, not a big deal to use distilled.  Washing, I would still use tap.  Its soft here and leaves a spotless board if removed right away with air and keep the board hot.

Looked at the main chemical listed on the MSDS sheet for Branson.  That lead me to DOW chemical which has a good doc covering use, handling, etc.  Sounded like you don't want a rail car of >90% leaking into a river.  Far as concentrations we are talking about, it didn't sound like down the drain for small dilute amounts was world ending.  Even there they listed check local requirements.  Pretty sure if I call my small city treatment plant ask them about some unheard of chemical, its hell no without them even looking at it.  Where the heck can you get a list of some obscure chemical and the acceptable local limit?  I didn't look into the other chemical they listed in the MSDS but it was far less part of the product.  Its 50% A and less than 10% B.  Fun fact, if you heat A in concentration...its also flammable.  Can't see how my use would ever result in this without using it straight and boiling all the water out.

http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0952/0901b803809522f5.pdf?filepath=amines/pdfs/noreg/111-01374.pdf&fromPage=GetDoc

I'm putting 1.25 cups in 10L and only dumping a handful of times a year.  If someone else find something otherwise, I certainly would rethink my disposal process.  The fire hazard compared to IPA is a nothing burger, even using beakers.

[orion242]

And on another point.  I have had this unit 4 years now.  Even if I'm somehow shorting the life by repositioning things while its running, the replacement cost vs earned value is nothing.  I check it with a watt meter from time to time just to make sure the ultrasonic capacity is still what it should be, still running strong.  Dies tomorrow, would get another without hesitation for my needs.

I run this unit empty, aka water only, for 1 min shots all the time, just to make the temp reading accurate on initial warmup.

[wilfred]

ALDI in Australia have an ultrasonic cleaner on sale today for $30. Which seems pretty cheap.

I haven't taken it out of the box yet but some YT reviews seemed positive. All I can say so far is it is about the size of a toaster.

[soldar]

ALDI in Australia have an ultrasonic cleaner on sale today for $30. Which seems pretty cheap.

I haven't taken it out of the box yet but some YT reviews seemed positive. All I can say so far is it is about the size of a toaster.

I have a similar one purchased at LIDL. I do not use it that much so I cannot say if it would last many hours of use.

I also have one of those ultra-sonic hockey puck shaped things they put in the bottom of decorative fountains to make mist and which can also be used as air humidifiers. You can just drop it at the bottom of whatever container you want to use.  I don't know if it has a name you can search for. Obviously you can use it with water and detergent but I would not risk using it with aggressive solvents. It is convenient in that it can be used in a really big tub. Just move it around ... or use several at the same time.

E.T.A.: https://www.amazon.com/CNZ-Fogger-Replacement-Mister-Lights/dp/B00AO1ZOME/