Flux remover with brush in plastic causes ESD damage?

[Flyback]

Hi,
Would you agree, this flux-remover with brush applicator can cause ESD damage?...Eg , if brushed over chips....we have a board with what appears to be an ESD damaged LTC3721-1, after brushing over it with this applicator. The brush is on the end of a plastic holder as you can see...

Flux remover

 

[JimB]

Maybe.

If you read the datasheet, it makes no mention of the product being ESD safe.

Looking at the list of "applications"

It carefully makes no mention of semiconductor devices.

JimB

 

[Flyback]

Thanks, i did wonder if by "printed circuit boards" they kind of include "assembled PCBs"?
But i suspect you are right.....the mounted brush is set in plastic, so i would think it was an ESD hazard if anything?....i am amazed its even said to be allowed anywhere near electronics components.

 

[rjenkinsgb]

If you read the usage instructions:

For industrial use only. Read MSDS carefully prior to use. Spray 4-6” from surface to clean. Wash parts from top to bottom, allowing the liquid to flush away dirt and dissolved grease. For precise application use attached extension tube. Product is Flammable - Do not use near sources of ignition and energized equipment.

Nowhere does it say to allow the container/brush to contact the item being cleaned...

However, I regularly clean machine tool CNC PCBs with bulk IPA and a paintbrush. I have never had a board fail due to that. Static damage from a liquid applicator seems rather strange.

The most likely time for static damage to occur is when something first touched the board, as that's the instant any difference in voltages is equalised. The first touch when handling should always be to a ground or power hole, screen or terminal.

Once contact is established, there should be no way a high voltage can accumulate.

One common scenario for static damage is people using wrist straps but not a full static-safe work area - the items they handle could be charged to high voltage and initial contact can zap the board.

 

[rjenkinsgb]

Just a bit of near comedy value stuff, while on the subject of cleaning PCBs:
Why electrical cabinet doors need to be kept closed and filters cleaned regularly!

The machine was apparently behaving erratically for a few weeks, then failed completely and we got called in to diagnose it.
The dust in a typical machine shop is largely metallic, plus carbon from cast iron. Overall, it's pretty conductive.
I'm amazed this one lasted as long as it did, and did not suffer any permanent damage!

(It's the main CNC module, several thousand pounds to replace it).

What it's supposed to look like, once cleaned:

 

[JimB]

Flyback
Also consider that if this ESD event happened in the past two weeks or so, the low temperatures in the UK could have led to a dry atmosphere which is conducive with bad ESD events.

rjenkins
That cnc board is an ugly mess!

JimB

 

[Nigel Goodwin]

Just a bit of near comedy value stuff, while on the subject of cleaning PCBs:
Why electrical cabinet doors need to be kept closed and filters cleaned regularly!

The machine was apparently behaving erratically for a few weeks, then failed completely and we got called in to diagnose it.
The dust in a typical machine shop is largely metallic, plus carbon from cast iron. Overall, it's pretty conductive.
I'm amazed this one lasted as long as it did, and did not suffer any permanent damage!

(It's the main CNC module, several thousand pounds to replace it).

View attachment 139663

What it's supposed to look like, once cleaned:

View attachment 139664

A good job for a vacuum cleaner and a soft paint brush

Which was how we used to clean out CRT television sets, although of course the dust isn't conductive and didn't cause any problems. We used to vacuum them out when we repaired them, mainly because it's too messy otherwise - we wouldn't advise cleaning the inside of your TV if its not faulty, as it won't help anything cleaning it out, and (if you're clumsy) you might actually cause damage. In the CNC case though, it's obviously as VERY good idea to regularly clean it.

We used to get occasional sets brought in for repair where the customer (always a MAN!!) had cleaned the sets insides, and broken something - and ones who had taken all the valves out, for cleaning and/or testing, but made no note of where they went back

Worst was the idiot who cleaned the set out (a Thorn 950 B&W), polished the valves, and screwed all those loose screws down properly - those ferrite 'loose screws' in the IF transformers Still, it was the only time I ever had to do IF alignment on a TV set

 

[Flyback]

wow.....amazing dust-scape with the CNC!
I woudlnt know where to start to clean that. Vacuum would worry me a bit in case any ESD effects from moving air from a hoover....but i guess you had it con coated too.

 

[rjenkinsgb]

No conformal coating - if there was, the dust would not be able to short things out.

That was an unusually "dry" one, most CNC and drive boards that need cleaning have mist from coolant or oil mixed in with the dust, giving it a consistency anything from like heavy oil to something like cooked-on chip fat.

 

[For The Popcorn]

Thanks, i did wonder if by "printed circuit boards" they kind of include "assembled PCBs"?

I may be a little slow, but why would there be
flux on a bare circuit board? Flux is left after soldering – you know, attaching parts to a circuit board – so "printed circuit boards" obviously means assembled circuit boards.

And if you were removing dust/crap buildup from a circuit board, why would you think flux remover would be a good answer?

 

[Flyback]

I may be a little slow, but why would there be
flux on a bare circuit board? Flux is left after soldering – you know, attaching parts to a circuit board – so "printed circuit boards" obviously means assembled circuit boards.

Thats what i thought, but maybe they meant pcbs comprising just resistors (eg dummy load boards), etc etc...or dirty great DIPs that are immune to ESD?...who knows, they dont say, another "message in a bottle" to the manufac coming up i think.