I meant to add that acetone is methyl-methyl ketone. On Fri, Dec 8, 2017 at 8:35 PM, Sean Breheny wrote: > MEK is in the same family (ketones) as acetone. Ketones are molecules > consisting of two alkane chains (like methyl, ethyl, butyl, propyl, etc.) > joined by a carbonyl group (carbon double-bonded to an oxygen). MEK has > somewhat higher toxicity than acetone but it isn't all that nasty (compar= ed > to benzene or the chlorinated methanes). I think it was banned because it > is a persistent environmental pollutant. > > I am very surprised that you were able to use MEK to dissolve IC packages= .. > Did you heat it up to do that? How long did it take? > > I have done some IC "de-capping" and the only way I've learned to do it i= s > using either concentrated hot nitric acid (works quickly - in about 5 > minutes) or concentrated hot sulfuric acid (takes much longer, about an > hour). > > On Fri, Dec 8, 2017 at 2:56 PM, Jean-Paul Louis wrote: > >> I read all about those solvents, and I am surprised that no-one has yet >> mentioned MEK (Methyl Ethyl Ketone). I used it long before it was banned >> from Manufacturing Floor. Mostly was to dissolve epoxy packaging on IC >> before >> doing a die inspection with electron microscope. Also used to dissolve >> potting >> compound for some very critical repairs. >> >> That was a real nasty solvent, but we used good precautions like gloves, >> masks and vented hoods above test area. >> >> Just another $0.02, >> Jean-Paul >> N1JPL >> >> >> >> > On Dec 8, 2017, at 7:31 AM, Sean Breheny wrote: >> > >> > Bunny suits?! That seems a bit over-the-top unless this was an >> application >> > where you were spraying large quantities (several liters) into the air= .. >> > >> > I obviously have not done independent research on this - I am only >> going by >> > what I've read in MSDS and other published sources that I read before >> using >> > these chemicals. The US Centers for Disease Control lists the IDLH >> > (Immediately Dangerous to Life or Health) threshold at 500ppm for both >> > benzene and toluene but they allow up to 100ppm permissible exposure >> level >> > in the workplace for toluene but only 1 ppm for benzene. They also do >> not >> > mention any risk of cancer for toluene but they do for benzene. So, I'= m >> not >> > saying that toluene is just dandy and no precautions are needed, but >> rather >> > that it is considerably safer than its "parent" molecule benzene for >> > long-term exposure. >> > >> > I also just learned that toluene is a significant risk to pregnant wom= en >> > with regard to possible miscarriage so I guess it can be very nasty fo= r >> > some people. >> > >> > Sean >> > >> > >> > On Fri, Dec 8, 2017 at 4:13 AM, wrote: >> > >> >>> >> >>> Toluene is also not all that nasty. It is methylbenzene but the meth= yl >> >> group >> >>> seems to prevent most of the carcinogenic action. Maximum safe >> short-term >> >>> dose is less than acetone/isopropanol. >> >>> >> >> >> >> Well, that doesn't equate to the hoops we had to jump through to use = a >> >> toluene based conformal coat on our PCBs. A suitable booth with high >> volume >> >> air extraction and use of full bunny suits while handling it. >> >> >> >> >> >> >> >> -- >> >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> >> View/change your membership options at >> >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> >> > -- >> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> > View/change your membership options at >> > http://mailman.mit.edu/mailman/listinfo/piclist >> >> Just my $0.02, >> >> Jean-Paul >> N1JPL >> >> >> >> >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .