Need to win a bet

I was told a long time ago that should never used compressed air to clean a cct board. As there will be static electricity and will fry the board. I was pretty new when i was told this. Always thought it was true but now one of are IT guys says can use any compressed air to clean cct boards and computers. Anybody have any thoughts on this.

I would say if its off maybe, the only thing I can think against it would be the fact that you blow debris all over the place, if part of that debris is metalic and it shorts a few components then you will have problems.

EDIT: I have cleaned circuits using a special vacuum cleaner with anit-static safeguards.

Sure, as a sfaety precaution, you should turn off the equipment before making any maintainance. I have clean boards with compressed air blower for 5 years and no problem happened till now.

I think who told you that was making a joke .
Just take care not to apply a high pressure air.

The problem with "standard" compressed air is that it almost always contains some moisture, and perhaps a little oil. I think the mositure oil mixture is the major concern, even when the moisture evaporates, a little oil may be left behind, which my cause a short.

In most compressed air systems in factories some oil is added to the compressed air to reduce friction in valves and cylinders. Sometimes this oil is added right at the compressor, mostly it is added at the point where the machine is connected to the compreesd air outlet (in the so-called conditioning unit).

Normally the compressed air isn't totally free of moisture, that's why this conditioning unit also has a water separator in it.

Bot water (unless it's completely pure) and oil are bad for electronic parts, but if you can get rid of both by using a correctly built conditioning unit, then there's nothing wrong with using compressed air to clean PCB's.

In fact, when I was working for my previous employer, we had some PLCs we had to clean in a special way. These PLCs were used in an environment where there was a mix of greased air (the outlet of the valves in the machine) and aluminium dust. This mixture settled on the PCBs of our PLCs and made shorts after about 8 or 9 months of use. So to avoid this we cleaned the PLCs every 6 months. We first rinsed the PCBs with trichlorethylene (don't know if the spelling is right, we called it simply tri at the time) and then dried them with dry, oil-free compressed air. After that the boards were ready for use again.

Kind regards,

Obviously no one here has seen circuit boards being made.

After they go thru the solder machine they go into an industrial size dishwasher. The maintenance guys send their really dirty tools thru to clean them. They are then dried with lots of compressed air. The air is filtered but still high pressure.

Many years ago I hooked up an old tape NC machine to a 286 computer. When the keyboard got full of chips I took it home and ran it thru the dishwasher. Worked every time.

i would be a bit more careful about this. my answer is - it depends. cleaning boards using air, water or special liquids is fine in many situations and i've been washing number of things in the bath tub or dishwasher without special liquids (just warm water with some dishwasher liquid). the thing to remember is what type of contaminants we are dealing with, particle size and density of the board.
anything conductive can be a problem. the times have changed in pcb manufacturing. early PCs had wide traces and greater pin clearances which ware much less likely to serve as anchor for some dirt to collect and stay there after washing/rinsing/drying. also technology has changed a lot with higher impedances everywhere. combine those with much lower height or clearance between chip and PCB and you have something to think about. some 95% of components are SMT nowdays, this simply didn't exist 25 years ago. sure they do washing when manufacturing PCBs and after wave soldering but they still make sure not to drop buckets of dirt or metal shaving on fine PCB structures crawded with high density SMDs.
some guys wanted to try to cool their PC in regular organic oil. not good idea but it works at least for a while:
http://www.tomshardware.com/2006/02/02/strip_out_the_fans/

Hey thanks all. I caught some one at work using the the air compressor. When i said they should use the canned air instead. Was told it was a silly thing to say. Just remember in the big plant i worked on was told off pretty good when the maintance sup saw me using the air hose on a plc rack that was off.

Chop, that is something you will see happen all the time, each plant will have different ideas on proper procedures.

I personally would not use "plant air" to clean electronics because of what was mentioned earlier about oil and moisture, unless they have a VERY VERY good filtering process and it is filtered at the connection point anything could happen.

The problem occurs when people have not determined damage was caused from this because it may not happen immediately, I suspect your previous maintenance sup had learned the hard way.

I would not argue with them about it but you may want to offer them the possibility that using plant air can contaminate a board offering shorts to it. Depending on certain conditions canned air can also produce moisture which may be harmful.

Overall, when cleaning panels, I prefer the vacuum method but have used air in some cases. I have seen damage caused by the use of pressurized air.

Another aspect of using plant air is that it may be harmful to humans, pressurized air can make objects become projectiles which could harm someone. In the US many companies disallow or restrict the usage of air, for cleaning etc, to 30 PSI or less.

Chop,

I think the final answer would be, if the accumulated stuff on the board is more harmful than the oil and water in the available compressed air, then use the compressed air.

I worked in a plant where potassium carbonate was used. If any of that stuff accumulated on a circuit board (or starter contacts, or even the bare ends of wires), it was an assured short circuit. A little oil and water in that case was nothing, compared to the alternative. Blowing off with air was the first cleaning step, and the next was to use a rag soaked in vinegar. You had to neutralize the pot carb or it would keep oxidizing the electrical parts.

Don't u guys know most oil is not conductive, anyway a little oil or water will not harm a board if done while powered down, On more than one occasion spilt coffee on my keyboard, dismantled it, chucked the lot in a bowl of water, dried it & it's always worked.

I spent 15 years as an electronics engineer & never destroyed a board with water or compressed air, most of the boards I clean now (being in a factory maint. Dept) they are usually full of water from the process & a blast with electrical cleaner & a good blow down from the main comp air seems to work a treat.

True.. Most oil won't be conductive... But at the point of application(blowing on the circuit board after traveling through piping) odd's are pretty good that it's not just pure oil anymore. There's probably plenty of metal fragments, etc that have been picked up along the way. (but now I'm just nitpicking)(sorry)



Our problem here is with juice in the air... We've finally got air conditioners and doors that actually stay closed on most of our panels.(YAY) Previously, the tech that did most of the work on our ultrasonic sealers would to take the boards out of our sealers when they weren't working, and wash them off with warm water to take the dried sugar off, and then blow the water off. It worked(I guess), but made me cring whenever I saw him doing it.

In a nutshell... Yah, you can do it... And it probably works just fine... But I don't LIKE doing it, so I search for reasons not to do it.

Pure water is not a conductor, but combined with oil and minerals; which is what you get from most plant air systems, can be something that does not actually clean but can pit traces plus leave a conductive film that bridges conductive pathways.

The I have done it for 30 years is not a good reference. I have seen people that used air to "blow off" dirt from their clothes etc end up losing an eye or worse. I have seen machines, panels, etc being blown "out" but instead an object gets blown "in" and destroys something.

Canned air can be appropriate at times and many items can be washed with water, it depends. When water is used you must make sure it is dry, tap water has minerals that do make it conductive. It is better to dry boards etc with a heat gun or hair dryer than pressurized air, have to be careful with a heat gun too.

Here is something to think about. Most plant systems maintain at least 100 PSI, 100 pounds per square inch does not sound like much but convert it to another form...7.2 tons per square foot. That is equivalent to a baby elephant standing on your chest.

One, if not the most, talked about issue here is SAFETY, safety does not begin or end with the design of the machine. It begins and ends with ALL the people involved with a machine.

Whether or not there is water, oil, minerals etc in the air, you have to realize that when you use plant air that YOU HAVE A GUN IN YOUR HAND.

Call it nitpicking if you want too.

On an unrelated note... This conversation reminded me about a project I saw on the web a little while ago.

Instead of a water cooled computer system, they went into a case, sealed it, put some of the components on top, sealed the processor to the motherboard, and filled the case with vegetable oil for a cooling system. I think it was on Tom's hardware guide.....

I wouldn't want to do it myself, and wouldn't want one in my house... But it looked like an interesting project.