Post by thread:[EE]: Are cooking fumes corrosive?

I recently had an odd failure in an oven controller. The oven worked fine for quite a while. It failed, and I took the board out and found a short trace that was completely missing, down to inside a via, and some of the pre-tinned copper was gone from an adjacent pad exposing bare copper. Didn't look like a mechanical force had scraped it off, it looked more like it was etched off. The board was also covered with grease and located in the path of cooking fumes that escape the oven. We had been cooking hambugers in the oven, broiling them, and hambuger cooking fumes will definitely condense on things, being mostly evaporated grease and water. Anybody know if these kind of cooking fumes can corrode copper, or am I seeing a pattern that is not there? -- Lawrence Lile Sr. Project Engineer Salton inc. Toastmaster Div. 573-446-5661 Voice 573-446-5676 Fax -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

At 02:29 PM 7/17/02 -0500, you wrote: >I recently had an odd failure in an oven controller. The oven worked fine >for quite a while. It failed, and I took the board out and found a short >trace that was completely missing, down to inside a via, and some of the >pre-tinned copper was gone from an adjacent pad exposing bare copper. >Didn't look like a mechanical force had scraped it off, it looked more like >it was etched off. The board was also covered with grease and located in >the path of cooking fumes that escape the oven. We had been cooking >hambugers in the oven, broiling them, and hambuger cooking fumes will >definitely condense on things, being mostly evaporated grease and water. >Anybody know if these kind of cooking fumes can corrode copper, or am I >seeing a pattern that is not there? Maybe it arced. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" spam_OUTspeffTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Yes, Animal fat and some plant fatty acids are very corrosive to copper and other types of metal. The term "conjugated linoleic acid" refers to a group of several variants of linoleic acid (also called octadecadienoic acid), an essential fatty acid. Variants of linoleic acid differ from one another in the type and arrangement of their chemical bonds. Use a good conformal coating on your boards. Gordon Varney http://www.iamnee.com {Quote hidden}> > I recently had an odd failure in an oven controller. The oven worked fine > for quite a while. It failed, and I took the board out and found a short > trace that was completely missing, down to inside a via, and some of the > pre-tinned copper was gone from an adjacent pad exposing bare copper. > Didn't look like a mechanical force had scraped it off, it looked more like > it was etched off. The board was also covered with grease and located in > the path of cooking fumes that escape the oven. We had been cooking > hambugers in the oven, broiling them, and hambuger cooking fumes will > definitely condense on things, being mostly evaporated grease and water. > Anybody know if these kind of cooking fumes can corrode copper, or am I > seeing a pattern that is not there? > > > -- Lawrence Lile > Sr. Project Engineer > Salton inc. Toastmaster Div. > 573-446-5661 Voice > 573-446-5676 Fax > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Among the more potent naturally occurring anticarcinogens is conjugated linoleic acid (CLA), a fatty acid found mainly in milk fat. The compound was first isolated in 1983 (from ground beef), by a research team led by Michael W. Pariza, Ph.D., of the University of Wisconsin. Gordon Varney http://www.iamnee.com {Quote hidden}> > Yes, Animal fat and some plant fatty acids are very corrosive to copper and other types of metal. > > The term "conjugated linoleic acid" refers to a group of several variants of linoleic acid (also called > octadecadienoic > acid), an essential fatty acid. Variants of linoleic acid differ from one another in the type and arrangement of their > chemical bonds. > > Use a good conformal coating on your boards. > > > Gordon Varney > http://www.iamnee.com > > > > > > > I recently had an odd failure in an oven controller. The oven worked fine > > for quite a while. It failed, and I took the board out and found a short > > trace that was completely missing, down to inside a via, and some of the > > pre-tinned copper was gone from an adjacent pad exposing bare copper. > > Didn't look like a mechanical force had scraped it off, it looked more like > > it was etched off. The board was also covered with grease and located in > > the path of cooking fumes that escape the oven. We had been cooking > > hambugers in the oven, broiling them, and hambuger cooking fumes will > > definitely condense on things, being mostly evaporated grease and water. > > Anybody know if these kind of cooking fumes can corrode copper, or am I > > seeing a pattern that is not there? > > > > > > -- Lawrence Lile > > Sr. Project Engineer > > Salton inc. Toastmaster Div. > > 573-446-5661 Voice > > 573-446-5676 Fax > > > > -- > > http://www.piclist.com hint: The list server can filter out subtopics > > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > > > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

I'd say they do not corrode anything unless there is voltage in the item. As in electrolytic corrosion. This seems to be very common in household equipment. Come to think of it condensed water with unsaturated fat acids in it is an electrolyte. You should look into conformal coating (at least) imho. Good luck finding a FDA approved one (not that solder is FDA approved for use in food related devices). Peter On Wed, 17 Jul 2002, Lawrence Lile wrote: {Quote hidden}>I recently had an odd failure in an oven controller. The oven worked fine >for quite a while. It failed, and I took the board out and found a short >trace that was completely missing, down to inside a via, and some of the >pre-tinned copper was gone from an adjacent pad exposing bare copper. >Didn't look like a mechanical force had scraped it off, it looked more like >it was etched off. The board was also covered with grease and located in >the path of cooking fumes that escape the oven. We had been cooking >hambugers in the oven, broiling them, and hambuger cooking fumes will >definitely condense on things, being mostly evaporated grease and water. >Anybody know if these kind of cooking fumes can corrode copper, or am I >seeing a pattern that is not there? > > >-- Lawrence Lile >Sr. Project Engineer >Salton inc. Toastmaster Div. >573-446-5661 Voice >573-446-5676 Fax > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

I verified today that I really am seeing corrosion from cooking fumes. We were doing a "flame containment " test which is required by UL, to see if an oven will contain a combusting food load in the inside. Some of the smoke, or whatever it is, condensed and built up on the circuit board, causing a component to open and a sooty mess. Close inspection showed a lot of corrosion wher ethe dripping gunk touched the component leads, classic green corroded copper. Later we'll repeat the test, catch some of the gunk and do a litmus test on it. I told my intern that Electronics engineers need to be Chemists, Physicists, Mechanical Engineers, know about glue, solvents, strength of materials, acid/base chemistry, corrosion, quality control, purchasing, packaging, Industrial Engineering and every other science in addition to knowing something about electronics. In fact, for a long time Ford would hire electronics engineers to design suspensions, instead of mechanical engineers, because electronics engineers understood damped oscillating systems better than the nuts and bolts crowd (This has changed, though). See, those mechanical engineers have it easy, they just study nuts and bolts. Remember the Tacoma Narrows Bridge (Hammock)? --Lawrence {Original Message removed}

At 02:19 PM 7/18/02 -0500, you wrote: >I verified today that I really am seeing corrosion from cooking fumes. We >were doing a "flame containment " test which is required by UL, to see if an >oven will contain a combusting food load in the inside. Some of the smoke, >or whatever it is, condensed and built up on the circuit board, causing a >component to open and a sooty mess. Close inspection showed a lot of >corrosion wher ethe dripping gunk touched the component leads, classic green >corroded copper. Later we'll repeat the test, catch some of the gunk and do >a litmus test on it. Interesting. Are you going to bring a sample with you next week? I had an application in an industrial plant where we had failures of relays and wound coils due to corrosion (black in color) of the copper wires, at the ends and through pinholes. The boards were not affected because we used a cheap but effective coating on them. Had me scratching my head for a few days. ;-) Ate right through AWG35 or so wires. Didn't seem to affect the operators, they were all the same no matter how long they had been exposed. ;-) >I told my intern that Electronics engineers need to be Chemists, Physicists, >Mechanical Engineers, know about glue, solvents, strength of materials, >acid/base chemistry, corrosion, quality control, purchasing, packaging, >Industrial Engineering and every other science in addition to knowing >something about electronics. In fact, for a long time Ford would hire >electronics engineers to design suspensions, instead of mechanical >engineers, because electronics engineers understood damped oscillating >systems better than the nuts and bolts crowd (This has changed, though). Are the computers getting better or the mech engs? >See, those mechanical engineers have it easy, they just study nuts and >bolts. Remember the Tacoma Narrows Bridge (Hammock)? I've always thought the civil engineers (oxymoron?) had it the easiest, if they weren't sure of the calculations they could always throw another few thousand tons of fill in there. If you try that in an aerospace application, it literally would never get off the ground. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam@spam@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.