# Could you have an electric or electronic circuit board with a component filled with H2O? **URL:** \ **Category:** Factual Questions\ **Created:** [May 4, 2014, 1:03pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632 "2014-05-04T13:03:04Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![Ranger\_Jeff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranger_jeff/32/2065_2.png) [@Ranger\_Jeff](https://boards.straightdope.com/u/Ranger_Jeff)\ **Post date:** [May 4, 2014, 5:56pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/21 "2014-05-04T17:56:38Z")
> [@beowulff](#): > > Just _try_ and find a consumer electronics product with a component containing mercury! Mercury switches are common in thermostats. There are also mercury relays. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 4, 2014, 6:01pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/22 "2014-05-04T18:01:30Z")
> [@Ranger\_Jeff](#): > > Mercury switches are common in thermostats. There are also mercury relays. Yeah? When was the last time you looked? [Here - Find me one.](http://www.homedepot.com/b/Heating-Venting-Cooling-Thermostats/N-5yc1vZc4lf) ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [May 4, 2014, 6:53pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/23 "2014-05-04T18:53:06Z")
But, according to the wiki I was sent from here (thanks **Peter Morris!** ) I can’t wait to tell people how the “tilt” alarm and lockdown works in vending machines. SD rocks! ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 4, 2014, 8:27pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/24 "2014-05-04T20:27:19Z")
> [@Leo\_Bloom](#): > > But, according to the wiki I was sent from here (thanks **Peter Morris!** ) I can’t wait to tell people how the “tilt” alarm and lockdown works in vending machines. > > SD rocks! The tilt mechanism in my pinball machines is a plum bob inside a circular conductive ring. ---
**Author:** ![Little\_Pig](https://avatars.discourse-cdn.com/v4/letter/l/c57346/32.png) [@Little\_Pig](https://boards.straightdope.com/u/Little_Pig)\ **Post date:** [May 4, 2014, 10:30pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/25 "2014-05-04T22:30:35Z")
> [@Francis\_Vaughan](#): > > As to the OP. The [Cray-2](http://en.wikipedia.org/wiki/Cray-2) must rate as one of the best examples of the idea. Yeup. “Instead of making one larger circuit board, each “card” would instead consist of a 3-D stack of eight, connected together in the middle of the boards using pins sticking up from the surface (known as “pogos” or “z-pins”). The cards were packed right on top of each other, so the resulting stack was only about 3 inches high. With this sort of density there was no way any conventional air-cooled system would work; there was too little room for air to flow between the ICs. Instead the system would be immersed in a tank of a new inert liquid from 3M, Fluorinert. The cooling liquid was forced sideways through the modules under pressure, and the flow rate was roughly one inch per second. The heated liquid was cooled using chilled water heat exchangers and returned to the main tank. Work on the new design started in earnest in 1982, several years after the original start date.” I believe the whole computer was hand-wired too. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [May 4, 2014, 10:41pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/26 "2014-05-04T22:41:05Z")
What about the [Electrolytic Tank](http://books.google.co.uk/books?id=npI8B805hLQC&pg=PA4&lpg=PA4&dq=analog+computer+electrolytic+tank&source=bl&ots=nmb9WawFUn&sig=L0TcdezJw4myi8b87-z_S3_KbMM&hl=en&sa=X&ei=5L9mU8uRIoKdO6SngbAF&ved=0CDgQ6AEwAg#v=onepage&q=analog%20computer%20electrolytic%20tank&f=false) analog computer? ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [May 5, 2014, 5:50am UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/27 "2014-05-05T05:50:50Z")
> [@Little\_Pig](#): > > I believe the whole computer was hand-wired too. The modules were socketed, but the between socket signal connections were done with hand assembled wire wrapped twisted pairs. The actual length of the interconnects mattered. This style of construction went back at least to the CDC 6600 (however that machine was built from discrete transistors in little modules about 2x3 inches in size. (I have a few in my collection. Seymore Cray is credited with the design of each module himself.) Many machines of the 60’s and 70’s were built with wire wrapped backplanes, but the use of length calibrated twisted pairs was a bit more special. ---
**Author:** ![Little\_Pig](https://avatars.discourse-cdn.com/v4/letter/l/c57346/32.png) [@Little\_Pig](https://boards.straightdope.com/u/Little_Pig)\ **Post date:** [May 5, 2014, 6:47pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/28 "2014-05-05T18:47:36Z")
> [@Francis\_Vaughan](#): > > The modules were socketed, but the between socket signal connections were done with hand assembled wire wrapped twisted pairs. The actual length of the interconnects mattered. This style of construction went back at least to the CDC 6600 (however that machine was built from discrete transistors in little modules about 2x3 inches in size. (I have a few in my collection. Seymore Cray is credited with the design of each module himself.) > > Many machines of the 60’s and 70’s were built with wire wrapped backplanes, but the use of length calibrated twisted pairs was a bit more special. Francis Vaughan, I went to see the[Lee Friedlander: The Cray Photographs.](http://museum.stanford.edu/news_room/friedlander.html) exhibit at Stanford last year. Petty cool. More[here.](http://www.amazon.com/CRAY-CHIPPEWA-FALLS-Photography-Friedlander/dp/B001LUUTUE) ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [May 5, 2014, 11:39pm UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/29 "2014-05-05T23:39:01Z")
> [@beowulff](#): > > Just _try_ and find a consumer electronics product with a component containing mercury! Here’s three: Fluorescent bulbs, primary batteries, canned tuna. Ok, two. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [May 6, 2014, 1:38am UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/30 "2014-05-06T01:38:30Z")
> [@Little\_Pig](#): > > Francis Vaughan, I went to see the[Lee Friedlander: The Cray Photographs.](http://museum.stanford.edu/news_room/friedlander.html) exhibit at Stanford last year. Petty cool. More[here.](http://www.amazon.com/CRAY-CHIPPEWA-FALLS-Photography-Friedlander/dp/B001LUUTUE) Argh. That looks like $200 I can’t afford to spend, spent. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 6, 2014, 2:15am UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/31 "2014-05-06T02:15:52Z")
> [@beowulff](#): > > Yeah? > > When was the last time you looked? > > [Here - Find me one.](http://www.homedepot.com/b/Heating-Venting-Cooling-Thermostats/N-5yc1vZc4lf) You do realize that not everyone has changed out their T-stat for a new one, right? I would bet I could find a dozen Mercury stats in a five minute walk in my neighborhood. Add to the list trunk/under hood/vanity mirror lights have all used Mercury in the past. Again many of those cars are still on the road. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 6, 2014, 3:13am UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/32 "2014-05-06T03:13:22Z")
> [@Rick](#): > > You do realize that not everyone has changed out their T-stat for a new one, right? > I would bet I could find a dozen Mercury stats in a five minute walk in my neighborhood. > Add to the list trunk/under hood/vanity mirror lights have all used Mercury in the past. Again many of those cars are still on the road. Sure, if you go far enough back in history you can find all sorts of “unsafe” products ([Radithor](http://en.wikipedia.org/wiki/Radithor), anyone?). But, Mercury in significant quantities (not the microscopic amounts in CFLs) has not be used in consumer products in many years. We’re getting to that point with Lead, too. As a EE, that makes my life interesting. ---
**Author:** ![andrewm](https://avatars.discourse-cdn.com/v4/letter/a/c57346/32.png) [@andrewm](https://boards.straightdope.com/u/andrewm)\ **Post date:** [May 6, 2014, 3:26am UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/33 "2014-05-06T03:26:20Z")
Obligatory XKCD: [xkcd: Circuit Diagram](http://xkcd.com/730/) ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 6, 2014, 3:52am UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/34 "2014-05-06T03:52:26Z")
> [@beowulff](#): > > Sure, if you go far enough back in history you can find all sorts of “unsafe” products ([Radithor](http://en.wikipedia.org/wiki/Radithor), anyone?). But, Mercury in significant quantities (not the microscopic amounts in CFLs) has not be used in consumer products in many years. We’re getting to that point with Lead, too. As a EE, that makes my life interesting. Well houses in my neighborhood date from the mid 50s. When did they stop using Hg in stats? 1980? 1990? Anyone with a stat older than that has Hg in their stat. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 7, 2014, 10:52am UTC](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632/35 "2014-05-07T10:52:20Z")
Components that are designed to be soldered to a PCB would have a difficult time surviving the soldering process (using a reflow oven) if they contained water. Heck, even [trace amounts of moisture in certain components can cause popcorn cracking](http://www.kemet.com/Lists/TechnicalArticles/Attachments/184/Moisture%20Barrier.pdf). If a component contained moisture by design, it would have to be hand-soldered to the PCB. [Previous page](https://boards.straightdope.com/t/could-you-have-an-electric-or-electronic-circuit-board-with-a-component-filled-with-h2o/687632.md?page=1)