How important are ESD mats?

[Trinity]

A mixture of at least 50% water and 50% isopropanol has a better cleaning result than using it pure.

Why is that?

[pinkman]

Lots of good points in this thread.

Keep in mind that ESD damage can be cumulative, i.e. it may not be evident right away.  So, if you're working on anything you know is ESD sensitive which you will ultimately be sending out into the world for someone to use, always use proper ESD handling procedures.

If you're just doing personal test work at home/office and don't care, then do whatever is convenient and see what happens.  I do this.  About once a month, I end up with an IC that either stops functioning completely, or ends up with a pin that sinks waaaaay too much current.  The likely cause is ESD damage.  Once in a while I know it is EOS due to general carelessness with test leads and such, but more often than not, I am sure that I have not EOS'ed the pin and the only logical explanation is ESD damage.

[schopi68]

A mixture of at least 50% water and 50% isopropanol has a better cleaning result than using it pure.

Why is that?

afaik there are two main reasons:
- pure isopropanol evaporates to fast. So you need much more isopropanol (and the dissolved contaminations may be dried again bevor they are wiped up).
 The mix is much more volatile than water alone (lower boiling-point) - so it is drying faster than pure water.
- some contaminations are only watersoluble (i.e. salts).

BTW: it's better to use distilled water - so you do nat have to mind about residues.
In practice i decide how to mix up based on the intended use. To clean up from colophonium residues i use pure isopropanol, to clean up cases or front plates i use distilled water, to clean up the ESD-mat i use almost everything.

Apropos of colophonium residues - this would be a good new thread: In older HP repair-manuals i found references that it may be better to not clean up soldering residues after repair (depending on the flux used) because this can spread up and activate aggresive ingredients instead of removing them.

[sfiber]

I use strip and esd mats with together.There is a ground jack to make ground connection.I use them because of I own,but sometimes I am working with ssop chips and this products can be necessary to be sure.