DI Water Cleaning / Need To Control Resitivity More?

We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. THE THRASHING-AROUND: 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! ... and so it goes. What do you think?? Dave F

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| We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | THE THRASHING-AROUND: | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | ... and so it goes. What do you think?? | Dave F Dave, I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. Earl

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| We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | THE THRASHING-AROUND: | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | ... and so it goes. What do you think?? | Dave F This may or may not apply...but at least it is a concern. With our laser systems, DI-water is run through the heat exchangers. we use DI, in an effort to cut down the corosion caused by standard tap water. When the resistivity level gets to low Under 1 MEG, the water NEEDS to be changed, or the heat exchanger would start to degrade and would need to be replaced, or at least overhauled at the end of the year. I can't speak on what it affects in a PCB cleaning process, but just for longevity of your equipment alone, the water should be changed. -Ben

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| | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | THE THRASHING-AROUND: | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | ... and so it goes. What do you think?? | | Dave F | Dave, | I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. | My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. | Earl Earl: Ya got water and ya got water. Distilled water: The process of separating the water from the organic and inorganic contaminants through a combination of evaporation (or vaporization), cooling, and condensation. Deionized water: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure: First, positively-charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively-charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange. Deionized water is very corrosive it will leach particles from inside pipe that is why you have to use Poly or SS pipe. (What you take away from water, water wants back.) Demineralized water: Is the same as Deionized water Tap Water: High amounts of organics and inorganics in water that is treated at an municipality, Still has to be in guidelines of the local and Federal standards. Filtered Water: Is basically any the above depending on what you want to remove from water. We will follow this chatter with chemistry, most importantly how CO2 in the air dissolves in DI water. Later. Dave F

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Been Moving to a new house all week....Blah... But seriously, The corrosion eventually will cause problems.. -Ben

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| | | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | | THE THRASHING-AROUND: | | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | | ... and so it goes. What do you think?? | | | Dave F | | Dave, | | I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. | | My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. | | Earl | Earl: Ya got water and ya got water. | Distilled water: The process of separating the water from the organic and inorganic contaminants through a combination of evaporation (or vaporization), cooling, and condensation. | Deionized water: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure: | First, positively-charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively-charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. | The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange. | Deionized water is very corrosive it will leach particles from inside pipe that is why you have to use Poly or SS pipe. (What you take away from water, water wants back.) | Demineralized water: Is the same as Deionized water | Tap Water: High amounts of organics and inorganics in water that is treated at an municipality, Still has to be in guidelines of the local and Federal standards. | Filtered Water: Is basically any the above depending on what you want to remove from water. | We will follow this chatter with chemistry, most importantly how CO2 in the air dissolves in DI water. Later. | Dave F Dave, Thanks for the explanation. I do appreciate and understand what you say. What I would like to know, in response to your original concern, is what difference is there relative to solvent capability? In other words, how does DI water differ from tap water in its ability to disolve whatever it contacts - or its "corrosive" affects to which you point? Thanks again, Earl

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| | | | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | | | THE THRASHING-AROUND: | | | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | | | ... and so it goes. What do you think?? | | | | Dave F | | | Dave, | | | I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. | | | My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. | | | Earl | | Earl: Ya got water and ya got water. | | Distilled water: The process of separating the water from the organic and inorganic contaminants through a combination of evaporation (or vaporization), cooling, and condensation. | | Deionized water: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure: | | First, positively-charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively-charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. | | The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange. | | Deionized water is very corrosive it will leach particles from inside pipe that is why you have to use Poly or SS pipe. (What you take away from water, water wants back.) | | Demineralized water: Is the same as Deionized water | | Tap Water: High amounts of organics and inorganics in water that is treated at an municipality, Still has to be in guidelines of the local and Federal standards. | | Filtered Water: Is basically any the above depending on what you want to remove from water. | | We will follow this chatter with chemistry, most importantly how CO2 in the air dissolves in DI water. Later. | | Dave F | Dave, | Thanks for the explanation. I do appreciate and understand what you say. What I would like to know, in response to your original concern, is what difference is there relative to solvent capability? In other words, how does DI water differ from tap water in its ability to disolve whatever it contacts - or its "corrosive" affects to which you point? | Thanks again, | Earl Earl: The cation beds generate a bunch of H+ ions, which go streaming into the anion beds, which throw-off a bunch of OH- ions. Many of the H+ anf OH- ions reunite to from water. We're going to have un-reunited ions. You konow it has to happen. These left-over H+ or OH- ions are not happy. First, they try to corrode my piping, but get frustrated because I've used SS or poly piping. So, next they end-up getting sprayed, along with the rest of the water on the printed circuit boards I'm trying to clean. What next? Is there a reaction between the ions and materials in the air? Or do the ions make it to the surface of the board? These ions are not the kind to remain polarized for very long. Later. Dave F

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| | | | | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | | | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | | | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | | | | THE THRASHING-AROUND: | | | | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | | | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | | | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | | | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | | | | ... and so it goes. What do you think?? | | | | | Dave F | | | | Dave, | | | | I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. | | | | My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. | | | | Earl | | | Earl: Ya got water and ya got water. | | | Distilled water: The process of separating the water from the organic and inorganic contaminants through a combination of evaporation (or vaporization), cooling, and condensation. | | | Deionized water: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure: | | | First, positively-charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively-charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. | | | The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange. | | | Deionized water is very corrosive it will leach particles from inside pipe that is why you have to use Poly or SS pipe. (What you take away from water, water wants back.) | | | Demineralized water: Is the same as Deionized water | | | Tap Water: High amounts of organics and inorganics in water that is treated at an municipality, Still has to be in guidelines of the local and Federal standards. | | | Filtered Water: Is basically any the above depending on what you want to remove from water. | | | We will follow this chatter with chemistry, most importantly how CO2 in the air dissolves in DI water. Later. | | | Dave F | | Dave, | | Thanks for the explanation. I do appreciate and understand what you say. What I would like to know, in response to your original concern, is what difference is there relative to solvent capability? In other words, how does DI water differ from tap water in its ability to disolve whatever it contacts - or its "corrosive" affects to which you point? | | Thanks again, | | Earl | Earl: The cation beds generate a bunch of H+ ions, which go | streaming into the anion beds, which throw-off a bunch of OH- ions. Many of the H+ anf OH- ions reunite to from water. We're going to have un-reunited ions. You konow it has to happen. These left-over H+ or OH- ions are not happy. First, they try to corrode my piping, but get frustrated because I've used SS or poly piping. So, next they end-up getting sprayed, along with the rest of the water on the printed circuit boards I'm trying to clean. What next? Is there a reaction between the ions and materials in the air? Or do the ions make it to the surface of the board? These ions are not the kind to remain polarized for very long. Later. Dave F Dave, I'm on your side. I just didn't realize the reactions effected by DI water. I'm sure this is true for many folks out here. Man, this is interesting. All I know, and that's not much on this subject, is water evaporates after sucking up everything in its path. What does DI leave behind to be so corrosive? Is it so much that's left behind in the air, or is it a state created when soluble? That is, is this condition a problem when O2 elements (whether deionized or not) react with whatever is present, as sulphur, chlorine, or nitrogen, or what? Is H2SO4, HCL, or NO3 the problem? Could this be acid rain in miniature? I don't know, but something to ponder further? Best wishes, Earl

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| | | | | | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | | | | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | | | | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | | | | | THE THRASHING-AROUND: | | | | | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | | | | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | | | | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | | | | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | | | | | ... and so it goes. What do you think?? | | | | | | Dave F | | | | | Dave, | | | | | I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. | | | | | My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. | | | | | Earl | | | | Earl: Ya got water and ya got water. | | | | Distilled water: The process of separating the water from the organic and inorganic contaminants through a combination of evaporation (or vaporization), cooling, and condensation. | | | | Deionized water: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure: | | | | First, positively-charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively-charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. | | | | The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange. | | | | Deionized water is very corrosive it will leach particles from inside pipe that is why you have to use Poly or SS pipe. (What you take away from water, water wants back.) | | | | Demineralized water: Is the same as Deionized water | | | | Tap Water: High amounts of organics and inorganics in water that is treated at an municipality, Still has to be in guidelines of the local and Federal standards. | | | | Filtered Water: Is basically any the above depending on what you want to remove from water. | | | | We will follow this chatter with chemistry, most importantly how CO2 in the air dissolves in DI water. Later. | | | | Dave F | | | Dave, | | | Thanks for the explanation. I do appreciate and understand what you say. What I would like to know, in response to your original concern, is what difference is there relative to solvent capability? In other words, how does DI water differ from tap water in its ability to disolve whatever it contacts - or its "corrosive" affects to which you point? | | | Thanks again, | | | Earl | | Earl: The cation beds generate a bunch of H+ ions, which go | | streaming into the anion beds, which throw-off a bunch of OH- ions. Many of the H+ anf OH- ions reunite to from water. We're going to have un-reunited ions. You konow it has to happen. These left-over H+ or OH- ions are not happy. First, they try to corrode my piping, but get frustrated because I've used SS or poly piping. So, next they end-up getting sprayed, along with the rest of the water on the printed circuit boards I'm trying to clean. What next? Is there a reaction between the ions and materials in the air? Or do the ions make it to the surface of the board? These ions are not the kind to remain polarized for very long. Later. Dave F | Dave, | I'm on your side. I just didn't realize the reactions effected by DI water. I'm sure this is true for many folks out here. Man, this is interesting. | All I know, and that's not much on this subject, is water evaporates after sucking up everything in its path. What does DI leave behind to be so corrosive? | Is it so much that's left behind in the air, or is it a state created when soluble? That is, is this condition a problem when O2 elements (whether deionized or not) react with whatever is present, as sulphur, chlorine, or nitrogen, or what? Is H2SO4, HCL, or NO3 the problem? Could this be acid rain in miniature? | I don't know, but something to ponder further? | Best wishes, | Earl Earl: It's a little bit like acid rain. So we have H+ and OH- ions running around in the water. The CO2 in the water and in the air and the OH- ions combine to for HCO3- ions. I don't know what happens next. A lot of it has to do with the particular ionic residues, resulting from board fab and assembly processing, and metals on the board. Certainly some of it's good. I guess the H+, OH-, and HCO3- ions will tend to scrub those residues that are ionic from the board. You know what I know. Dave F

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| | | | | | | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | | | | | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | | | | | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | | | | | | THE THRASHING-AROUND: | | | | | | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | | | | | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | | | | | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | | | | | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | | | | | | ... and so it goes. What do you think?? | | | | | | | Dave F | | | | | | Dave, | | | | | | I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. | | | | | | My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. | | | | | | Earl | | | | | Earl: Ya got water and ya got water. | | | | | Distilled water: The process of separating the water from the organic and inorganic contaminants through a combination of evaporation (or vaporization), cooling, and condensation. | | | | | Deionized water: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure: | | | | | First, positively-charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively-charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. | | | | | The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange. | | | | | Deionized water is very corrosive it will leach particles from inside pipe that is why you have to use Poly or SS pipe. (What you take away from water, water wants back.) | | | | | Demineralized water: Is the same as Deionized water | | | | | Tap Water: High amounts of organics and inorganics in water that is treated at an municipality, Still has to be in guidelines of the local and Federal standards. | | | | | Filtered Water: Is basically any the above depending on what you want to remove from water. | | | | | We will follow this chatter with chemistry, most importantly how CO2 in the air dissolves in DI water. Later. | | | | | Dave F | | | | Dave, | | | | Thanks for the explanation. I do appreciate and understand what you say. What I would like to know, in response to your original concern, is what difference is there relative to solvent capability? In other words, how does DI water differ from tap water in its ability to disolve whatever it contacts - or its "corrosive" affects to which you point? | | | | Thanks again, | | | | Earl | | | Earl: The cation beds generate a bunch of H+ ions, which go | | | streaming into the anion beds, which throw-off a bunch of OH- ions. Many of the H+ anf OH- ions reunite to from water. We're going to have un-reunited ions. You konow it has to happen. These left-over H+ or OH- ions are not happy. First, they try to corrode my piping, but get frustrated because I've used SS or poly piping. So, next they end-up getting sprayed, along with the rest of the water on the printed circuit boards I'm trying to clean. What next? Is there a reaction between the ions and materials in the air? Or do the ions make it to the surface of the board? These ions are not the kind to remain polarized for very long. Later. Dave F | | Dave, | | I'm on your side. I just didn't realize the reactions effected by DI water. I'm sure this is true for many folks out here. Man, this is interesting. | | All I know, and that's not much on this subject, is water evaporates after sucking up everything in its path. What does DI leave behind to be so corrosive? | | Is it so much that's left behind in the air, or is it a state created when soluble? That is, is this condition a problem when O2 elements (whether deionized or not) react with whatever is present, as sulphur, chlorine, or nitrogen, or what? Is H2SO4, HCL, or NO3 the problem? Could this be acid rain in miniature? | | I don't know, but something to ponder further? | | Best wishes, | | Earl | Earl: It's a little bit like acid rain. | So we have H+ and OH- ions running around in the water. The CO2 in the water and in the air and the OH- ions combine to for HCO3- ions. I don't know what happens next. | A lot of it has to do with the particular ionic residues, resulting from board fab and assembly processing, and metals on the board. Certainly some of it's good. I guess the H+, OH-, and HCO3- ions will tend to scrub those residues that are ionic from the board. | You know what I know. | Dave F Earl: Have someone toss a penny into a washer using DI water. It'll turn green. Corrosiveness is to be directly related to resistivity. Makes sense. DI water is corrosive. Tap water is not corrosive. The lower resistivity DI is more like tap water than high resitivity DI. Dave F

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| | | | | | | | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | | | | | | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | | | | | | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | | | | | | | THE THRASHING-AROUND: | | | | | | | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | | | | | | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | | | | | | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | | | | | | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | | | | | | | ... and so it goes. What do you think?? | | | | | | | | Dave F | | | | | | | Dave, | | | | | | | I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. | | | | | | | My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. | | | | | | | Earl | | | | | | Earl: Ya got water and ya got water. | | | | | | Distilled water: The process of separating the water from the organic and inorganic contaminants through a combination of evaporation (or vaporization), cooling, and condensation. | | | | | | Deionized water: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure: | | | | | | First, positively-charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively-charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. | | | | | | The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange. | | | | | | Deionized water is very corrosive it will leach particles from inside pipe that is why you have to use Poly or SS pipe. (What you take away from water, water wants back.) | | | | | | Demineralized water: Is the same as Deionized water | | | | | | Tap Water: High amounts of organics and inorganics in water that is treated at an municipality, Still has to be in guidelines of the local and Federal standards. | | | | | | Filtered Water: Is basically any the above depending on what you want to remove from water. | | | | | | We will follow this chatter with chemistry, most importantly how CO2 in the air dissolves in DI water. Later. | | | | | | Dave F | | | | | Dave, | | | | | Thanks for the explanation. I do appreciate and understand what you say. What I would like to know, in response to your original concern, is what difference is there relative to solvent capability? In other words, how does DI water differ from tap water in its ability to disolve whatever it contacts - or its "corrosive" affects to which you point? | | | | | Thanks again, | | | | | Earl | | | | Earl: The cation beds generate a bunch of H+ ions, which go | | | | streaming into the anion beds, which throw-off a bunch of OH- ions. Many of the H+ anf OH- ions reunite to from water. We're going to have un-reunited ions. You konow it has to happen. These left-over H+ or OH- ions are not happy. First, they try to corrode my piping, but get frustrated because I've used SS or poly piping. So, next they end-up getting sprayed, along with the rest of the water on the printed circuit boards I'm trying to clean. What next? Is there a reaction between the ions and materials in the air? Or do the ions make it to the surface of the board? These ions are not the kind to remain polarized for very long. Later. Dave F | | | Dave, | | | I'm on your side. I just didn't realize the reactions effected by DI water. I'm sure this is true for many folks out here. Man, this is interesting. | | | All I know, and that's not much on this subject, is water evaporates after sucking up everything in its path. What does DI leave behind to be so corrosive? | | | Is it so much that's left behind in the air, or is it a state created when soluble? That is, is this condition a problem when O2 elements (whether deionized or not) react with whatever is present, as sulphur, chlorine, or nitrogen, or what? Is H2SO4, HCL, or NO3 the problem? Could this be acid rain in miniature? | | | I don't know, but something to ponder further? | | | Best wishes, | | | Earl | | Earl: It's a little bit like acid rain. | | So we have H+ and OH- ions running around in the water. The CO2 in the water and in the air and the OH- ions combine to for HCO3- ions. I don't know what happens next. | | A lot of it has to do with the particular ionic residues, resulting from board fab and assembly processing, and metals on the board. Certainly some of it's good. I guess the H+, OH-, and HCO3- ions will tend to scrub those residues that are ionic from the board. | | You know what I know. | | Dave F | Earl: Have someone toss a penny into a washer using DI water. It'll turn green. | Corrosiveness is to be directly related to resistivity. Makes sense. DI water is corrosive. Tap water is not corrosive. The lower resistivity DI is more like tap water than high resitivity DI. | Dave F Dave- I Understand the fact that the lower the resistivity level, the less corrosive it is. But what still confuses me is why... Is the HCO3- the added component that increases the resistivity? or does there happen to be others taken out of the air, that have not yet been noticed? -Ben

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| | | | | | | | | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | | | | | | | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | | | | | | | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | | | | | | | | THE THRASHING-AROUND: | | | | | | | | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | | | | | | | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | | | | | | | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | | | | | | | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | | | | | | | | ... and so it goes. What do you think?? | | | | | | | | | Dave F | | | | | | | | Dave, | | | | | | | | I always knew (from earliest chemistry classes) water, any water, was considered the "universal" solvent. The stuff disolves minute amounts of glass if placed in that type container. | | | | | | | | My question is: How does DI water differ. I needs to know so I'll know what you know about the stuff. | | | | | | | | Earl | | | | | | | Earl: Ya got water and ya got water. | | | | | | | Distilled water: The process of separating the water from the organic and inorganic contaminants through a combination of evaporation (or vaporization), cooling, and condensation. | | | | | | | Deionized water: The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure: | | | | | | | First, positively-charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively-charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. | | | | | | | The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange. | | | | | | | Deionized water is very corrosive it will leach particles from inside pipe that is why you have to use Poly or SS pipe. (What you take away from water, water wants back.) | | | | | | | Demineralized water: Is the same as Deionized water | | | | | | | Tap Water: High amounts of organics and inorganics in water that is treated at an municipality, Still has to be in guidelines of the local and Federal standards. | | | | | | | Filtered Water: Is basically any the above depending on what you want to remove from water. | | | | | | | We will follow this chatter with chemistry, most importantly how CO2 in the air dissolves in DI water. Later. | | | | | | | Dave F | | | | | | Dave, | | | | | | Thanks for the explanation. I do appreciate and understand what you say. What I would like to know, in response to your original concern, is what difference is there relative to solvent capability? In other words, how does DI water differ from tap water in its ability to disolve whatever it contacts - or its "corrosive" affects to which you point? | | | | | | Thanks again, | | | | | | Earl | | | | | Earl: The cation beds generate a bunch of H+ ions, which go | | | | | streaming into the anion beds, which throw-off a bunch of OH- ions. Many of the H+ anf OH- ions reunite to from water. We're going to have un-reunited ions. You konow it has to happen. These left-over H+ or OH- ions are not happy. First, they try to corrode my piping, but get frustrated because I've used SS or poly piping. So, next they end-up getting sprayed, along with the rest of the water on the printed circuit boards I'm trying to clean. What next? Is there a reaction between the ions and materials in the air? Or do the ions make it to the surface of the board? These ions are not the kind to remain polarized for very long. Later. Dave F | | | | Dave, | | | | I'm on your side. I just didn't realize the reactions effected by DI water. I'm sure this is true for many folks out here. Man, this is interesting. | | | | All I know, and that's not much on this subject, is water evaporates after sucking up everything in its path. What does DI leave behind to be so corrosive? | | | | Is it so much that's left behind in the air, or is it a state created when soluble? That is, is this condition a problem when O2 elements (whether deionized or not) react with whatever is present, as sulphur, chlorine, or nitrogen, or what? Is H2SO4, HCL, or NO3 the problem? Could this be acid rain in miniature? | | | | I don't know, but something to ponder further? | | | | Best wishes, | | | | Earl | | | Earl: It's a little bit like acid rain. | | | So we have H+ and OH- ions running around in the water. The CO2 in the water and in the air and the OH- ions combine to for HCO3- ions. I don't know what happens next. | | | A lot of it has to do with the particular ionic residues, resulting from board fab and assembly processing, and metals on the board. Certainly some of it's good. I guess the H+, OH-, and HCO3- ions will tend to scrub those residues that are ionic from the board. | | | You know what I know. | | | Dave F | | Earl: Have someone toss a penny into a washer using DI water. It'll turn green. | | Corrosiveness is to be directly related to resistivity. Makes sense. DI water is corrosive. Tap water is not corrosive. The lower resistivity DI is more like tap water than high resitivity DI. | | Dave F | Dave- | I Understand the fact that the lower the resistivity level, the less corrosive it is. But what still confuses me is why... | Is the HCO3- the added component that increases the resistivity? | or does there happen to be others taken out of the air, that have not yet been noticed? | -Ben Ben: Natural water has impurities that allow it to conduct electricity and taste good. As you filter more and more of these additives, the water becomes more pure and its ability to conduct electricity decreases ( resistivity increases). And it tastes worse. I'd don't know how the HCO3- fits in. I don't know its concentration. It could just become an impurity that lower the waters resistivity. There's a chemistry teacher out in St Peter, MN that told me about it and I'm trying to get in touch with him. Did you know you should NOT drink DI water? It will make you sick. Check the MSDS at http://MSDS.PDC.CORNELL.EDU/msds/hazcom/261/80170.txt I clipped the following quote from the link below (on resins) to help answer your question: "Natural water supplies contain dissolved salts which dissociate in water to form charged particles called ions. These ions are usually present in relatively low concentrations and permit the water to conduct electricity. They are sometimes referred to as electrolytes. These ionic impurities can lead to problems in cooling and heating systems, steam generation, and manufacturing. The common ions that are encountered in most waters include the positively charged cations; calcium and magnesium (hardness forming cations, which make a water "hard") and sodium. The negatively charged anions include alkalinity, sulfate, chloride, and silica. Ion exchange resins are particularly well suited for the removal of these ionic impurities for several reasons: the resins have high capacities for ions that are found in low concentrations, the resins are stable and readily regenerated, temperature effects are for the most part negligible, and the process is excellent for both large and small installations, for example, from home water softeners to huge utility installations." Dave F

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| We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | THE THRASHING-AROUND: | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | ... and so it goes. What do you think?? | Dave F So Dave, where are you going to take this interesting proposition? Earl Moon

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| | We�ve been thinking again and need your help in sorting through an issue related to deionized (DI) water cleaning of assembled boards. | | THE BACKGROUND: The water reclaiming systems goes: gross filter, fine filter, carbon bed, mixed resin bed, cation, bed, anion bed, and fine filter. Resistivity is monitored to determine the need to replace the beds. With fresh beds, resistivity starts-out around 18 meg and declines to 1 meg when we determine which beds to replace. | | THE THINKING: DI water is a fairly aggressive solvent used to clean boards. We allow it to vary over a wide range before taking action. We should control DI water better. | | THE THRASHING-AROUND: | | 1 Control solvent (water) resistivity on a narrow range by "blending" tap water with the high resistivity reclaimed water to be consistent. | | 2 Y�re _____ !!! As long as we have clean boards, we�re good to go and don�t need to mess with resistivity, because it�s just a tool to help us know when to change beds. Clean boards are the issue!!! | | 3 Yah but, we know the DI water can be corrosive. It can burn through copper water piping and turn the metal on crystal cans and DIN connectors brown. And who knows what else it does? We should control that stuff. | | 4 And let me tell you something else!!! Those old MIL-STD-2000 cleanliness specs and test methods don�t work with no-clean and water soluble fluxes anyhow!!! | | ... and so it goes. What do you think?? | | Dave F | So Dave, where are you going to take this interesting proposition? | Earl Moon Earl: We're not sure. SMTNet responses are one stake in the ground. It's not real clear that we have practical options for controling resistivity. We are trying to understand the effects of "corrosiveness." Dave F

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