So. This famous 'brown glue' on circuit boards. How to remove it?

[cvanc]

This is the stuff that can cause trouble over time by going conductive, or even corrosive.  Is there any effective method to deal with it?  Can it be somehow removed, or is it pretty much a nightmare trying to get rid of it?

Is this just a consumer electronics thing, or does professional / industrial gear have it too?  Thanks.

[SeanB]

Freezer spray then scrape it off while still frozen works best. Solvents that can attack it tend also to be bad for components, so scraping generally is best. Does not have to all be off, just mostly so it will not track between parts and pins. A dental pick is best to get it out from pins. Finally yes it appears all over, though the better manufacturers will not use it, but will use an acetoxy free silicone instead, or a polyurethane epoxy that sets like rock.

[tautech]

Cut a small piece from it and if it seems porus like foam remove it, it will be hygroscopic and absorb moisture especially when powered down for a time or put into storage. Then if you power it on.....boom. 

Seen it in proprietary slimline HP PC PSU's.

[wraper]

I'd say if there is not sign of corrosion, then don't bother. It would be really stupid to destroy the device while trying to prevent "possible" malfunction in the future. Also,  there might be multiple types of the glue which look similar but aren't the same. At least I didn't notice that the presence of such glue = 100% corrosion in the future. Also if this glue isn't over the tracks but just holding the parts to copper free area of the PCB (like large capacitors), I wouldn't bother at all.

[Radio Tech]

Picture of the "brown glue area" speaks volumes.

[free_electron]

you meanhardened flux ?
flux remover or some isopropyl alcohol will do fine.

[Len]

you meanhardened flux ?

No, he means this:

https://youtu.be/yy8NS2zejhQ

[wblock]

An interesting video, unfortunately marred by the #1 rule of instructional videos: "Light is the enemy."

Here are some quick examples pulled from my junk pile.