Isopropyl Alcohol for Cleaning Flux
in [Basics]
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From: Paul E. Schoen on 31 Jul 2010 20:44 "GregS" <zekfrivo(a)zekfrivolous.com> wrote in message news:i2kovd$d95$1(a)usenet01.srv.cis.pitt.edu... > > I also remember fellow in our section, working on something new, computer > "terminal monitors". There was some kind of problem, and he was taking > some > boards into the mens room to wash them off. i guess they worked after > that. Long ago (1980?) I remember having problems with leakage on a board that stored voltages in polystyrene capacitors using CMOS switches and op-amps, but the voltage would bleed off too quickly to be useful as a "memory". We tried all sorts of flux removers and it still didn't work well enough. But I had an idea that it might be ionic contaminants such as salt, so I took a board into the mens room and scrubbed it with hand soap and flushed it with hot water. Then I dried it with a heat gun, and "voila" it worked like a champ rather than a chump. I have had good results with isopropyl alcohol as a flux remover, applied with a stiff "acid" brush with bristles cut short. It does leave a white residue. But then I follow with a spray of detergent, scrubbing once again, and the heat gun to dry it thoroughly. You need to be careful about overheating, so I hold the board by hand on the edges and move the hot air around. My fingers will hurt before I overheat the board. Seems to work very well. Paul
From: William Sommerwerck on 31 Jul 2010 20:50 > I remember having problems with leakage on a board that > stored voltages in polystyrene capacitors using CMOS > switches and op-amps, but the voltage would bleed off too > quickly to be useful as a "memory". We tried all sorts of > flux removers and it still didn't work well enough. But I had > had an idea that it might be ionic contaminants such as > salt, so I took a board into the mens room and scrubbed > it with hand soap and flushed it with hot water. Then I dried > it with a heat gun, and "voila" it worked like a champ rather > than a chump. Interesting observation. Question... Wouldn't distilled water alone flush off ionic contaminants?
From: Paul E. Schoen on 31 Jul 2010 20:58 "William Sommerwerck" <grizzledgeezer(a)comcast.net> wrote in message news:i32gbp$hnm$1(a)news.eternal-september.org... >> I remember having problems with leakage on a board that >> stored voltages in polystyrene capacitors using CMOS >> switches and op-amps, but the voltage would bleed off too >> quickly to be useful as a "memory". We tried all sorts of >> flux removers and it still didn't work well enough. But I had >> had an idea that it might be ionic contaminants such as >> salt, so I took a board into the mens room and scrubbed >> it with hand soap and flushed it with hot water. Then I dried >> it with a heat gun, and "voila" it worked like a champ rather >> than a chump. > > Interesting observation. > > Question... Wouldn't distilled water alone flush off ionic contaminants? Probably. But there may be some sort of oily residue that will be removed by the detergent. And hot water from the tap is much cheaper. It may be good to do a final rinse with distilled or deionized water. I have heard that some people stack their boards in a dishwasher. But my method works for me and is is very practical for small quantities. Paul
From: Michael A. Terrell on 2 Aug 2010 08:57 "Paul E. Schoen" wrote: > > "William Sommerwerck" <grizzledgeezer(a)comcast.net> wrote in message > news:i32gbp$hnm$1(a)news.eternal-september.org... > >> I remember having problems with leakage on a board that > >> stored voltages in polystyrene capacitors using CMOS > >> switches and op-amps, but the voltage would bleed off too > >> quickly to be useful as a "memory". We tried all sorts of > >> flux removers and it still didn't work well enough. But I had > >> had an idea that it might be ionic contaminants such as > >> salt, so I took a board into the mens room and scrubbed > >> it with hand soap and flushed it with hot water. Then I dried > >> it with a heat gun, and "voila" it worked like a champ rather > >> than a chump. > > > > Interesting observation. > > > > Question... Wouldn't distilled water alone flush off ionic contaminants? > > Probably. But there may be some sort of oily residue that will be removed by > the detergent. And hot water from the tap is much cheaper. It may be good to > do a final rinse with distilled or deionized water. I have heard that some > people stack their boards in a dishwasher. But my method works for me and is > is very practical for small quantities. We used a citrus based cleaner in a commercial board washing machine at Microdyne. It was a modified stainless steel industrial dishwasher with a separate solvent tank and fresh water wash. Then the boards went into a board drying oven for 12 to 24 hours. This was for small runs of boards stuffed and reflow soldered in house.
From: GregS on 2 Aug 2010 10:03
In article <WtCdnar_6NJbXcvRnZ2dnUVZ_gadnZ2d(a)earthlink.com>, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > >"Paul E. Schoen" wrote: >> >> "William Sommerwerck" <grizzledgeezer(a)comcast.net> wrote in message >> news:i32gbp$hnm$1(a)news.eternal-september.org... >> >> I remember having problems with leakage on a board that >> >> stored voltages in polystyrene capacitors using CMOS >> >> switches and op-amps, but the voltage would bleed off too >> >> quickly to be useful as a "memory". We tried all sorts of >> >> flux removers and it still didn't work well enough. But I had >> >> had an idea that it might be ionic contaminants such as >> >> salt, so I took a board into the mens room and scrubbed >> >> it with hand soap and flushed it with hot water. Then I dried >> >> it with a heat gun, and "voila" it worked like a champ rather >> >> than a chump. >> > >> > Interesting observation. >> > >> > Question... Wouldn't distilled water alone flush off ionic contaminants? >> >> Probably. But there may be some sort of oily residue that will be removed by >> the detergent. And hot water from the tap is much cheaper. It may be good to >> do a final rinse with distilled or deionized water. I have heard that some >> people stack their boards in a dishwasher. But my method works for me and is >> is very practical for small quantities. > > > We used a citrus based cleaner in a commercial board washing machine >at Microdyne. It was a modified stainless steel industrial dishwasher >with a separate solvent tank and fresh water wash. Then the boards went >into a board drying oven for 12 to 24 hours. This was for small runs of >boards stuffed and reflow soldered in house. I noticed citrus based degreasers leave behind oil. Thats a bad thing when you really want to paint something thinking it will work. Bad for tape sticking also. I think I allready mentioned mens room board cleaning. greg |